Materials

21 pages, 5094 KB

Open AccessEditor’s ChoiceArticle

Parameter Optimization of a Surface Mechanical Rolling Treatment Process to Improve the Surface Integrity and Fatigue Property of FV520B Steel by Machine Learning

by Yongxin Zhou, Zheng Xing, Qianduo Zhuang, Jiao Sun and Xingrong Chu

Materials 2024, 17(18), 4505; https://doi.org/10.3390/ma17184505 - 13 Sep 2024

Cited by 4 | Viewed by 2156

Abstract

Surface integrity is a critical factor that affects the fatigue resistance of materials. A surface mechanical rolling treatment (SMRT) process can effectively improve the surface integrity of the material, thus enhancing the fatigue property. In this paper, an analysis of variance (ANOVA) and [...] Read more.

Surface integrity is a critical factor that affects the fatigue resistance of materials. A surface mechanical rolling treatment (SMRT) process can effectively improve the surface integrity of the material, thus enhancing the fatigue property. In this paper, an analysis of variance (ANOVA) and signal-to-noise ratio (SNR) are performed by orthogonal experimental design with SMRT parameters as variables and surface integrity indicators as optimization objectives, and the support vector machine-active learning (SVM-AL) model is proposed based on machine learning theory. The entire model includes three rounds of AL processes. In each round of the AL process, the SMRT parameters with relative average deviation and high output values from cross-validation are selected for the additional experimental supplement. The results show that the prediction accuracy and generalization ability of the SVM-AL model are significantly improved compared to the support vector machine (SVM) model. A fatigue test was also carried out, and the fatigue property of the SMRT specimens predicted by the SVM-AL model is also higher than that of the other specimens. Full article

(This article belongs to the Special Issue Mechanics, Fatigue and Fracture of Metallic Materials (Second Edition))

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18 pages, 5125 KB

Open AccessEditor’s ChoiceArticle

Short Fatigue-Crack Growth from Crack-like Defects under Completely Reversed Loading Predicted Based on Cyclic R-Curve

by Keisuke Tanaka and Yoshiaki Akiniwa

Materials 2024, 17(18), 4484; https://doi.org/10.3390/ma17184484 - 12 Sep 2024

Cited by 3 | Viewed by 1419

Abstract

Understanding short fatigue-crack propagation behavior is inevitable in the defect-tolerant design of structures. Short cracks propagate differently from long cracks, and the amount of crack closure plays a key role in the propagation behavior of short cracks. In the present paper, the buildup [...] Read more.

Understanding short fatigue-crack propagation behavior is inevitable in the defect-tolerant design of structures. Short cracks propagate differently from long cracks, and the amount of crack closure plays a key role in the propagation behavior of short cracks. In the present paper, the buildup of fatigue-crack closure due to plasticity with crack extension from crack-like defects is simulated with a modified strip yield model, which leaves plastic stretch in the wake of the advancing crack. Crack-like defects are assumed to be closure-free and do not close even under compression. The effect of the size of crack-like defects on the growth and arrest of short cracks was systematically investigated and the cyclic R-curve derived. The cyclic R-curve determined under constant amplitude loading of multiple specimens is confirmed to be independent of the initial defect length. Load-shedding and ΔK-constant loading tests are employed to extend the cyclic R-curve beyond the fatigue limit determined under constant amplitude loading. The initiation stage of cracks is taken into account in R-curves when applied to smooth specimens. Full article

(This article belongs to the Special Issue Advances in High Cycle Fatigue and Fracture Failure of Metallic Materials and Components)

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14 pages, 4816 KB

Open AccessEditor’s ChoiceArticle

Influence of the Metallic Sublayer on Corrosion Resistance in Hanks’ Solution of 316L Stainless Steel Coated with Diamond-like Carbon

by Ewa Dobruchowska, Justyna Schulz, Viktor Zavaleyev, Jan Walkowicz, Tomasz Suszko and Bogdan Warcholinski

Materials 2024, 17(18), 4487; https://doi.org/10.3390/ma17184487 - 12 Sep 2024

Cited by 5 | Viewed by 1484

Abstract

The purpose of the study was to ascertain the corrosion resistance in Hanks’ solution of Cr-Ni-Mo stainless steel (AISI 316L) coated with diamond-like carbon (DLC) coatings to establish its suitability for biomedical applications, e.g., as temporary implants. The influence of the carbon coating [...] Read more.

The purpose of the study was to ascertain the corrosion resistance in Hanks’ solution of Cr-Ni-Mo stainless steel (AISI 316L) coated with diamond-like carbon (DLC) coatings to establish its suitability for biomedical applications, e.g., as temporary implants. The influence of the carbon coating thickness as well as the correlated effect of the metallic sublayer type and defects present in DLC films on corrosion propagation were discussed. The results obtained were compared with findings on the adhesion of DLC to the steel substrate. The synthesis of carbon thin films with Cr and Ti adhesive sublayers was performed using a combined DC and a high-power-impulse vacuum-arc process. Evaluation of the corrosion resistance was carried out by means of potentiodynamic polarisation tests and scanning electron microscopy. Adhesive properties of the sublayer/DLC coating systems were measured using a scratch tester. It was found that systems with Ti sublayers were less susceptible to the corrosion processes, particularly to pitting. The best anti-corrosion properties were obtained by merging Ti with a DLC coating with a thickness equal to 0.5 μm. The protective properties of the Cr/DLC systems were independent of the carbon coating thickness. On the other hand, the DLC coatings with the Cr sublayer showed better adhesion to the substrate. Full article

(This article belongs to the Collection Microstructure and Corrosion Behavior of Advanced Alloys)

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17 pages, 12952 KB

Open AccessEditor’s ChoiceArticle

Assessment of Changes in Selected Features of Pine and Birch Wood after Impregnation with Graphene Oxide

by Izabela Betlej, Sławomir Borysiak, Katarzyna Rybak, Barbara Nasiłowska, Aneta Bombalska, Zygmunt Mierczyk, Karolina Lipska, Piotr Borysiuk, Bogusław Andres, Małgorzata Nowacka and Piotr Boruszewski

Materials 2024, 17(18), 4464; https://doi.org/10.3390/ma17184464 - 11 Sep 2024

Cited by 2 | Viewed by 1173

Abstract

In this work, pine and birch wood were modified by graphene oxide using a single vacuum impregnation method. The research results indicate that the impregnation of wood with graphene oxide increases the crystallinity of cellulose in both pine and birch wood, and the [...] Read more.

In this work, pine and birch wood were modified by graphene oxide using a single vacuum impregnation method. The research results indicate that the impregnation of wood with graphene oxide increases the crystallinity of cellulose in both pine and birch wood, and the increase in crystallinity observed in the case of birch was more significant than in the case of pine. FT-IR analyses of pine samples impregnated with graphene oxide showed changes in intensity in the absorption bands of 400–600, 700–1500 cm⁻¹, and 3200–3500 cm⁻¹ and a peak separation of 1102 cm⁻¹, which may indicate new C-O-C connections. In the case of birch, only some differences were noticed related to the vibrations of the OH group. The proposed modification also affects changes in the color of the wood surface, with earlywood containing more graphene oxide than latewood. Analysis of scanning electron microscope images revealed that graphene oxide adheres flat to the cell wall. Considering the differences in the anatomical structure of both wood species, the research showed a statistically significant difference in water absorption and retention of graphene oxide in wood cells. Graphene oxide does not block the flow of water in the wood, as evidenced by the absorbability of the working liquid at the level of 580–602 kg/m³, which corresponds to the value of pure water absorption by wood in the impregnation method using a single negative pressure. In this case, higher graphene oxide retention values were obtained for pine wood. Full article

(This article belongs to the Section Advanced Materials Characterization)

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17 pages, 23305 KB

Open AccessFeature PaperEditor’s ChoiceArticle

In Situ Investigation of Tensile Response for Inconel 718 Micro-Architected Materials Fabricated by Selective Laser Melting

by Ioannis Filippos Kyriakidis, Nikolaos Kladovasilakis, Eleftheria Maria Pechlivani, Apostolos Korlos, Constantine David and Konstantinos Tsongas

Materials 2024, 17(17), 4433; https://doi.org/10.3390/ma17174433 - 9 Sep 2024

Cited by 5 | Viewed by 1984

Abstract

Topology optimization enables the design of advanced architected materials with tailored mechanical properties and optimal material distribution. This method can result in the production of parts with uniform mechanical properties, reducing anisotropy effects and addressing a critical challenge in metal additive manufacturing (AM). [...] Read more.

Topology optimization enables the design of advanced architected materials with tailored mechanical properties and optimal material distribution. This method can result in the production of parts with uniform mechanical properties, reducing anisotropy effects and addressing a critical challenge in metal additive manufacturing (AM). The current study aims to examine the micro-tensile response of Inconel 718 architected materials utilizing the Selective Laser Melting Technique. In this context, three novel architected materials, i.e., Octet, Schwarz Diamond (SD), and hybrid Schwarz Diamond and Face Centered Cubic (FCC), were tested in three different relative densities. The specimens were then subjected to uniaxial quasi-static tensile tests to determine their key mechanical properties, including elastic modulus, yield strength, and ultimate tensile strength (UTS), as well as the scaling laws describing the tensile response of each architected material. In situ Scanning Electron Microscopy (SEM) has been performed to observe the structure and grain morphology of the 3D printed specimens along with the phase transitions (elastic, plastic), the crack propagation, and the overall failure mechanisms. The results highlight the effect of the lattice type and the relative density on the mechanical properties of architected materials. Topologically optimized structures presented a 70–80% reduction in overall strength, while the SD and SD&FCC structures presented higher stretching dominated behavior, which was also verified by the n-value range (1–2) extracted from the identification of the scaling laws. Full article

(This article belongs to the Special Issue Fusion Bonding/Welding of Metal and Non-Metallic Materials)

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13 pages, 7271 KB

Open AccessEditor’s ChoiceArticle

In Situ Analysis of Binder Degradation during Catalyst-Accelerated Stress Test of Polymer Electrolyte Membrane Fuel Cells

by Donggeun Yoo, Sujung Park, Sohyeong Oh, Minsoo P. Kim and Kwonpil Park

Materials 2024, 17(17), 4425; https://doi.org/10.3390/ma17174425 - 9 Sep 2024

Cited by 8 | Viewed by 2032

Abstract

High-oxygen-permeability ionomers (HOPIs) are being actively developed to enhance the performance and durability of high-power polymer electrolyte membrane fuel cells (PEMFCs). While methods for evaluating binder performance are well-established, techniques for assessing binder durability and measuring its degradation in situ during the AST [...] Read more.

High-oxygen-permeability ionomers (HOPIs) are being actively developed to enhance the performance and durability of high-power polymer electrolyte membrane fuel cells (PEMFCs). While methods for evaluating binder performance are well-established, techniques for assessing binder durability and measuring its degradation in situ during the AST process remain limited. This study examines the distribution of relaxation times (DRT) and Warburg-like response (WLR) methods as in situ analysis techniques during the catalyst-accelerated stress test (AST) process. We conducted catalyst-ASTs (0.6–0.95 V cycling) for 20,000 cycles, monitoring changes using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). Contrary to expectations, during the catalyst-AST, the ion transport resistance of the binder decreased, indicating no binder degradation. Scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) analysis revealed that the degradation rate of the catalyst and the support was relatively higher than that of the binder, leading to a reduction in catalyst layer thickness and improved binder network formation. By applying the DRT method during the catalyst-AST process, we were able to measure the increase in oxygen reduction reaction (ORR) resistance and the decrease in proton transport resistance in situ. This allowed for the real-time detection of the reduction in catalyst layer thickness and improvements in ionomer networks due to catalyst and support degradation. These findings provide new insights into the complex interplay between catalyst degradation and binder performance, contributing to the development of more durable PEMFC components. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Advanced Materials Characterization)

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12 pages, 4585 KB

Open AccessEditor’s ChoiceArticle

Thin-Layer TiO₂ Membrane Fabrication by Condensed Layer Deposition

by Mohammed M. Numaan, Ahmed M. Jasim, Yangchuan Xing and Maria M. Fidalgo

Materials 2024, 17(17), 4436; https://doi.org/10.3390/ma17174436 - 9 Sep 2024

Cited by 3 | Viewed by 1215

Abstract

A novel approach to the fabrication of thin-film supported metal oxide membranes was investigated. Nanocoatings were obtained by the condensed layer deposition of TiO₂ on tubular microporous supports, applying multiple consecutive layers of TiO₂/polyaniline. The surface, cross-sectional structure, and morphology [...] Read more.

A novel approach to the fabrication of thin-film supported metal oxide membranes was investigated. Nanocoatings were obtained by the condensed layer deposition of TiO₂ on tubular microporous supports, applying multiple consecutive layers of TiO₂/polyaniline. The surface, cross-sectional structure, and morphology of the materials were investigated by electron microscopy. Their membrane-related properties were explored by permeability measurements, rejection, and fouling analysis, using polyethylene glycol (PEG) as test molecules. The SEM images showed that TiO₂ was successfully deposited on the surface, creating a layer with partial coverage of the support after each layer was deposited; consequently, the permeability of the membranes decreased gradually. Overall, the results of the flux and permeability of the membranes confirmed the coating. The transmembrane pressure (TMP) increased with each coating layer, while the rejection of the membrane showed gradual improvement. Full article

(This article belongs to the Special Issue Advancements in Thin Film Deposition Technologies)

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13 pages, 1547 KB

Open AccessEditor’s ChoiceArticle

Predicting Yield Strength and Plastic Elongation in Body-Centered Cubic High-Entropy Alloys

by Diego Ibarra Hoyos, Quentin Simmons and Joseph Poon

Materials 2024, 17(17), 4422; https://doi.org/10.3390/ma17174422 - 8 Sep 2024

Cited by 2 | Viewed by 2216

Abstract

We employ machine learning (ML) to predict the yield stress and plastic strain of body-centered cubic (BCC) high-entropy alloys (HEAs) in the compression test. Our machine learning model leverages currently available databases of BCC and BCC+B2 entropy alloys, using feature engineering to capture [...] Read more.

We employ machine learning (ML) to predict the yield stress and plastic strain of body-centered cubic (BCC) high-entropy alloys (HEAs) in the compression test. Our machine learning model leverages currently available databases of BCC and BCC+B2 entropy alloys, using feature engineering to capture electronic factors, atomic ordering from mixing enthalpy, and the D parameter related to stacking fault energy. The model achieves low Root Mean Square Errors (RMSE). Utilizing Random Forest Regression (RFR) and Genetic Algorithms for feature selection, our model excels in both predictive accuracy and interpretability. Rigorous 10-fold cross-validation ensures robust generalization. Our discussion delves into feature importance, highlighting key predictors and their impact on mechanical properties. This work provides an important step toward designing high-performance structural high-entropy alloys, providing a powerful tool for predicting mechanical properties and identifying new alloys with superior strength and ductility. Full article

(This article belongs to the Special Issue Advances in High Entropy Alloys and High Entropy Carbides: Microstructural and Mechanical Properties and Modeling)

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25 pages, 14228 KB

Open AccessEditor’s ChoiceReview

A Review on Metallurgical Issues in the Production and Welding Processes of Clad Steels

by Fabio Giudice, Severino Missori, Cristina Scolaro and Andrea Sili

Materials 2024, 17(17), 4420; https://doi.org/10.3390/ma17174420 - 8 Sep 2024

Cited by 13 | Viewed by 2872

Abstract

Carbon and low-alloy steel plates clad with stainless steel or other metals are a good choice to meet the demand for cost-effective materials to be used in many corrosive environments. Numerous technical solutions are developed for the production of clad steel plates, as [...] Read more.

Carbon and low-alloy steel plates clad with stainless steel or other metals are a good choice to meet the demand for cost-effective materials to be used in many corrosive environments. Numerous technical solutions are developed for the production of clad steel plates, as well as for their joining by fusion welding. For thick plates, a careful strategy is required in carrying out the multiple passes and in choosing the most suitable filler metals, having to take into account the composition of the base metal and the cladding layer. The specificity of the different processes and materials involved requires an adequate approach in the study of the metallurgical characteristics of clad steel, thus arousing the interest of researchers. Focusing mainly on ferritic steel plates clad with austenitic steel, this article aims to review the scientific literature of recent years which deals with both the production and the fusion welding processes. The metallurgical issues concerning the interfaces and the effects of microstructural characteristics on mechanical behaviour and corrosion resistance will be addressed; in particular, the effects on the fusion and thermally affected zones that form during the fusion welding and weld overlay processes will be analysed and discussed. Full article

(This article belongs to the Special Issue New Perspectives in Welding and Joining Processes of Metallic Materials)

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13 pages, 4081 KB

Open AccessEditor’s ChoiceArticle

Enhanced Raman Scattering in CVD-Grown MoS₂/Ag Nanoparticle Hybrids

by Dionysios M. Maratos, Antonios Michail, Alkeos Stamatelatos, Spyridon Grammatikopoulos, Dimitris Anestopoulos, Vassilis Tangoulis, Konstantinos Papagelis, John Parthenios and Panagiotis Poulopoulos

Materials 2024, 17(17), 4396; https://doi.org/10.3390/ma17174396 - 6 Sep 2024

Cited by 3 | Viewed by 2453

Abstract

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful, non-destructive technique for enhancing molecular spectra, first discovered in 1974. This study investigates the enhancement of Raman signals from single- and few-layer molybdenum disulfide (MoS₂) when interacting with silver nanoparticles. We synthesized a MoS [...] Read more.

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful, non-destructive technique for enhancing molecular spectra, first discovered in 1974. This study investigates the enhancement of Raman signals from single- and few-layer molybdenum disulfide (MoS₂) when interacting with silver nanoparticles. We synthesized a MoS₂ membrane primarily consisting of monolayers and bilayers through a wet chemical vapor deposition method using metal salts. The silver nanoparticles were either directly grown on the MoS₂ membrane or placed beneath it. Raman measurements revealed a significant increase in signal intensity from the MoS₂ membrane on the silver nanoparticles, attributed to localized surface plasmon resonances that facilitate SERS. Our results indicate that dichalcogenide/plasmonic systems have promising applications in the semiconductor industry. Full article

(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))

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13 pages, 4622 KB

Open AccessEditor’s ChoiceArticle

Diphenylamino-Modified Neutral Pt(II) Complexes: Their Aggregation-Induced Phosphorescent Emission and Picric Acid-Sensing Properties

by Qinglong Zhang, Yingying Yan, Rui Cai, Xiao-Na Li and Chun Liu

Materials 2024, 17(17), 4366; https://doi.org/10.3390/ma17174366 - 3 Sep 2024

Cited by 3 | Viewed by 1368

Abstract

Three neutral Pt(II) complexes with diphenylamino-modified 2-phenylpyridine derivatives as cyclometalating ligands and acetylacetone as the ancillary ligand exhibit aggregation-induced phosphorescent emission (AIPE) properties in THF/H₂O. The crystal structures of the complexes highlight the contributions of non-covalent Pt···Pt interactions and hydrogen bonds [...] Read more.

Three neutral Pt(II) complexes with diphenylamino-modified 2-phenylpyridine derivatives as cyclometalating ligands and acetylacetone as the ancillary ligand exhibit aggregation-induced phosphorescent emission (AIPE) properties in THF/H₂O. The crystal structures of the complexes highlight the contributions of non-covalent Pt···Pt interactions and hydrogen bonds to the AIPE properties. These AIPE-active Pt(II) complexes 1–3 have been successfully applied to detect picric acid (PA) in aqueous media, affording the lowest limit of detection at 70 nM. Furthermore, three Pt(II) complexes are able to detect PA in common water samples. The quenching of luminescence in the detection can be attributed to photo-induced electron transfer. Full article

(This article belongs to the Special Issue Advanced Materials for Luminescent Applications)

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13 pages, 10499 KB

Open AccessEditor’s ChoiceArticle

High Milling Time Influence on the Phase Stability and Electrical Properties of Fe₅₀Mn₃₅Sn₁₅ Heusler Alloy Obtained by Mechanical Alloying

by Florin Popa, Traian Florin Marinca, Niculina Argentina Sechel, Dan Ioan Frunză and Ionel Chicinaș

Materials 2024, 17(17), 4355; https://doi.org/10.3390/ma17174355 - 3 Sep 2024

Viewed by 933

Abstract

Fe₅₀Mn₃₅Sn₁₅ Heusler alloy, obtained by mechanical alloying, was subjected to larger milling times in the range of 30–50 h to study the phase stability and morphology. X-ray diffraction studies have shown that the milled samples crystallise in a [...] Read more.

Fe₅₀Mn₃₅Sn₁₅ Heusler alloy, obtained by mechanical alloying, was subjected to larger milling times in the range of 30–50 h to study the phase stability and morphology. X-ray diffraction studies have shown that the milled samples crystallise in a disordered A₂ structure. The A₂ structure was found to be stable in the milling range studied, contrary to the computation studies performed on this composition. Using Rietveld refinements, the lattice parameter, mean crystallite size, and lattice strain were computed. The nature of the obtained phases by milling was found to be nanocrystalline with values below 50 nm. A linear increase rate of 0.00713 (h⁻¹) was computed for lattice strain as the milling time increased. As the milling time increases, the lattice parameter of the cubic Heusler was found to have a decreasing behaviour, reaching 2.9517 Å at 50 h of milling. The morphological and elemental distribution—characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy—evidenced Mn and Sn phase clustering. As the milling time increased, the morphology of the sample was found to change. The Mn and Sn cluster size was quantified by elemental line profile. Electrical resistivity evolution with milling time was analysed, showing a peak for 40 h of milling time. Full article

(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))

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18 pages, 3736 KB

Open AccessEditor’s ChoiceArticle

New Bipolar Host Materials Based on Indolocarbazole for Red Phosphorescent OLEDs

by Sunwoo Park, Hyukmin Kwon, Sangwook Park, Saeyoung Oh, Kiho Lee, Hayoon Lee, Seokwoo Kang, Dongmin Park and Jongwook Park

Materials 2024, 17(17), 4347; https://doi.org/10.3390/ma17174347 - 2 Sep 2024

Cited by 1 | Viewed by 2148

Abstract

We designed and synthesized new indolocarbazole-triazine derivatives, 9-di-tert-butyl-5,7-bis(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-P-ICz) and 3,9-di-tert-butyl-5,7-bis(5′-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1′:3′,1″-terphenyl]-2′-yl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-TP-ICz), as new bipolar host materials for red phosphorescent OLEDs. In the film state, 2TRZ-P-ICz and 2TRZ-TP-ICz exhibited photoluminescence maxima at 480 nm and 488 nm, respectively. The dipole moment characteristics of [...] Read more.

We designed and synthesized new indolocarbazole-triazine derivatives, 9-di-tert-butyl-5,7-bis(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-P-ICz) and 3,9-di-tert-butyl-5,7-bis(5′-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1′:3′,1″-terphenyl]-2′-yl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-TP-ICz), as new bipolar host materials for red phosphorescent OLEDs. In the film state, 2TRZ-P-ICz and 2TRZ-TP-ICz exhibited photoluminescence maxima at 480 nm and 488 nm, respectively. The dipole moment characteristics of the new compounds under various solvent conditions were investigated using the Lippert–Mataga equation. The results showed that the dipole moment of 2TRZ-P-ICz is 26.9D, while that of 2TRZ-TP-ICz is 21.3D. The delayed fluorescence lifetimes were 0.188 μs for 2TRZ-P-ICz and 2.080 μs for 2TRZ-TP-ICz, with 2TRZ-TP-ICz showing TADF characteristics. Additionally, 2TRZ-TP-ICz was found to have a ΔEST of less than 0.2 eV. The triplet energy levels of the newly synthesized bipolar host materials were found to be 2.72 and 2.75 eV, confirming their suitability for use in red phosphorescent OLEDs. To investigate the carrier mobility of the synthesized materials, hole-only devices and electron-only devices were fabricated and tested. The hole mobility value at 1V was found to be 3.43 × 10⁻³ cm²/Vs for 2TRZ-P-ICz and 2.16 × 10⁻³ cm²/Vs for 2TRZ-TP-ICz. For electron mobility at 1V, 2TRZ-P-ICz showed a value of 4.41 × 10⁻⁹ cm²/Vs, while 2TRZ-TP-ICz exhibited a value of 9.13 × 10⁻⁹ cm²/Vs. As a result, when the new material was used as a host in red phosphorescent OLEDs, 2TRZ-TP-ICz achieved a current efficiency of 9.92 cd/A, an external quantum efficiency of 13.7%, CIE coordinates of (0.679, 0.319), and an electroluminescence maximum wavelength of 626 nm. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Chemistry)

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16 pages, 11171 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Macro- and Micro-Geometry of Models Made of Photopolymer Resins Using the PolyJet Method

by Paweł Turek, Anna Bazan, Grzegorz Budzik, Tomasz Dziubek and Łukasz Przeszłowski

Materials 2024, 17(17), 4315; https://doi.org/10.3390/ma17174315 - 30 Aug 2024

Cited by 2 | Viewed by 1465

Abstract

Additive manufacturing (AM) techniques are among the fastest-growing technologies for producing even the most geometrically complex models. Unfortunately, the lack of development of metrology guidelines for these methods, related to dimensional and geometry accuracy and surface roughness, significantly limits the commercialization of finished [...] Read more.

Additive manufacturing (AM) techniques are among the fastest-growing technologies for producing even the most geometrically complex models. Unfortunately, the lack of development of metrology guidelines for these methods, related to dimensional and geometry accuracy and surface roughness, significantly limits the commercialization of finished products manufactured using these methods. This paper aims to evaluate the macro- and micro-geometry of models manufactured using the PolyJet method from three types of photopolymer resins: Digital ABS Plus, RGD 720, and Vero Clear. For this purpose, test parts were designed and then manufactured on an Object 350 Connex3 3D printer. The Atos II Triple Scan optical system and the InfiniteFocusG4 microscope were used to evaluate macro- and micro-geometry, respectively. For both systems, measurement procedures were developed to obtain statistical results for evaluating geometric accuracy and surface roughness parameters. In the case of macro-geometry, for Digital ABS Plus and Vero Clear materials, 50% of the central deviations (between first quartile Q1 and third quartile Q3) lie within the range (−0.06, 0.03 mm) and for RGD 720 material within the range (−0.08, 0.01 mm). For micro-geometry, the arithmetic mean height (Sa) values for the Digital ABS Plus and Vero Clear samples were approximately 1.6 and 2.0 µm, respectively, while for RGD 720, it was 15.9 µm. The total roughness height expressed by reduced peak height (Spk) + core height (Sk) + reduced dale depth (Svk) for the Digital ABS Plus and Vero Clear samples was approximately 9.1 and 10.5 µm, respectively, while for the RGD 720, it was 101.9 µm. Full article

(This article belongs to the Special Issue Material Surface Topography Measurement, Analysis and Characterization)

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14 pages, 5955 KB

Open AccessEditor’s ChoiceArticle

Prediction of the Interface Behavior of a Steel/CFRP Hybrid Part Manufactured by Stamping

by Jae-Chang Ryu, Chan-Joo Lee, Do-Hoon Shin and Dae-Cheol Ko

Materials 2024, 17(17), 4291; https://doi.org/10.3390/ma17174291 - 30 Aug 2024

Cited by 1 | Viewed by 1067

Abstract

Carbon fiber-reinforced plastic (CFRP) is a lightweight material. The automotive industry has focused on producing a steel/CFRP hybrid part to reduce overall weight. After manufacturing, delamination can occur at the interface between the CFRP and steel owing to the hybrid part constituting dissimilar [...] Read more.

Carbon fiber-reinforced plastic (CFRP) is a lightweight material. The automotive industry has focused on producing a steel/CFRP hybrid part to reduce overall weight. After manufacturing, delamination can occur at the interface between the CFRP and steel owing to the hybrid part constituting dissimilar materials. However, most studies have focused only on designing the manufacturing processes for the hybrid part or evaluating the adhesive used at the interface. Therefore, it is necessary to predict the behavior of the interface after demolding the hybrid part. This study aimed to predict the interface behavior of a steel/CFRP hybrid part by considering its forming and cohesive properties. First, double cantilever beam (DCB) and end-notched flexure (ENF) tests were performed to obtain cohesive parameters, such as energy release rate of modes I and II (G_I, G_II). The experimentally obtained properties were applied to the bonding area of the hybrid part. Subsequently, a forming simulation was performed to obtain the stress of the steel blank in the hybrid part. The stress distribution after forming was utilized as the initial condition for spring-back simulation. Finally, the interface behavior of the hybrid part was predicted by a spring-back simulation. The simulation was conducted using the residual stress of steel outer and the cohesive properties on the interface, without the application of any external forces. The cases of spring-back simulation were divided as delamination occurrence and attached state. The simulation results for prediction of delamination occurrence and bonding showed good agreement in both cases with experimental ones. The proposed method would contribute to expanding the manufacturing of the hybrid part by stamping and reducing the manufacturing cost by prediction of delamination occurrence. Full article

(This article belongs to the Special Issue Advances in Hybrid Structure Manufacturing Technology)

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13 pages, 17420 KB

Open AccessEditor’s ChoiceArticle

Electrospun Polymeric Fiber Systems Inoculated with Cyanoacrylate Tissue Adhesive: A Novel Hemostatic Alternative during Open Surgery

by Victor P. Tosa, Alexandru Ilie-Ene, Septimiu C. Tripon, Amalia Mesaros, Radu Fechete, Nicoleta Tosa, Alexandra Csapai, George C. Dindelegan and Catalin O. Popa

Materials 2024, 17(17), 4318; https://doi.org/10.3390/ma17174318 - 30 Aug 2024

Cited by 3 | Viewed by 1550

Abstract

Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This [...] Read more.

Natural-based and synthetic tissue adhesives have attracted extensive attention in the last two decades for their ability to stabilize uncontrolled bleeding instances. However; these materials present several drawbacks during use that scientists have tried to minimize in order to optimize their usage. This study comprises the development of a novel wound dressing, combining the excellent properties of polylactic acid (PLA) non-woven textile, as substrate, obtained through electrospinning, and a cyanoacrylate-based (CA) tissue adhesive, for rapid hemostatic action. Thus, the fabrication of electrospun PLA membranes at three different PLA concentrations, the design and manufacturing of the support system and the production of surgical patches were carried out. SEM and FT-IR methods were employed for analyzing the morphology as well as the indicative markers for the shelf life evolution of the obtained patches. PLA fibers with well-defined structures and a mean diameter varying between 4.6 and 7.24 μm were obtained with the increase of the concentration of the PLA solutions. In vivo tests on a rat model as well as peeling tests for good patch adhesion on liver fragments harvested from the test animals, with a limit for the strength of the liver tissue of 1.5 N, were carried out. The devices exhibited excellent adhesion to the parenchymal tissue and a long enough shelf life to be used with success in surgical procedures, also facilitating prompt hemostatic action. Full article

(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))

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62 pages, 16763 KB

Open AccessEditor’s ChoiceReview

Epitaxial Growth of Ga₂O₃: A Review

by Imteaz Rahaman, Hunter D. Ellis, Cheng Chang, Dinusha Herath Mudiyanselage, Mingfei Xu, Bingcheng Da, Houqiang Fu, Yuji Zhao and Kai Fu

Materials 2024, 17(17), 4261; https://doi.org/10.3390/ma17174261 - 28 Aug 2024

Cited by 17 | Viewed by 7939

Abstract

Beta-phase gallium oxide (β-Ga₂O₃) is a cutting-edge ultrawide bandgap (UWBG) semiconductor, featuring a bandgap energy of around 4.8 eV and a highly critical electric field strength of about 8 MV/cm. These properties make it highly suitable for next-generation power [...] Read more.

Beta-phase gallium oxide (β-Ga₂O₃) is a cutting-edge ultrawide bandgap (UWBG) semiconductor, featuring a bandgap energy of around 4.8 eV and a highly critical electric field strength of about 8 MV/cm. These properties make it highly suitable for next-generation power electronics and deep ultraviolet optoelectronics. Key advantages of β-Ga₂O₃ include the availability of large-size single-crystal bulk native substrates produced from melt and the precise control of n-type doping during both bulk growth and thin-film epitaxy. A comprehensive understanding of the fundamental growth processes, control parameters, and underlying mechanisms is essential to enable scalable manufacturing of high-performance epitaxial structures. This review highlights recent advancements in the epitaxial growth of β-Ga₂O₃ through various techniques, including Molecular Beam Epitaxy (MBE), Metal-Organic Chemical Vapor Deposition (MOCVD), Hydride Vapor Phase Epitaxy (HVPE), Mist Chemical Vapor Deposition (Mist CVD), Pulsed Laser Deposition (PLD), and Low-Pressure Chemical Vapor Deposition (LPCVD). This review concentrates on the progress of Ga₂O₃ growth in achieving high growth rates, low defect densities, excellent crystalline quality, and high carrier mobilities through different approaches. It aims to advance the development of device-grade epitaxial Ga₂O₃ thin films and serves as a crucial resource for researchers and engineers focused on UWBG semiconductors and the future of power electronics. Full article

(This article belongs to the Section Electronic Materials)

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32 pages, 11300 KB

Open AccessEditor’s ChoiceReview

A Comprehensive Review of Stimuli-Responsive Smart Polymer Materials—Recent Advances and Future Perspectives

by Alicja Balcerak-Woźniak, Monika Dzwonkowska-Zarzycka and Janina Kabatc-Borcz

Materials 2024, 17(17), 4255; https://doi.org/10.3390/ma17174255 - 28 Aug 2024

Cited by 26 | Viewed by 9161

Abstract

Today, smart materials are commonly used in various fields of science and technology, such as medicine, electronics, soft robotics, the chemical industry, the automotive field, and many others. Smart polymeric materials hold good promise for the future due to their endless possibilities. This [...] Read more.

Today, smart materials are commonly used in various fields of science and technology, such as medicine, electronics, soft robotics, the chemical industry, the automotive field, and many others. Smart polymeric materials hold good promise for the future due to their endless possibilities. This group of advanced materials can be sensitive to changes or the presence of various chemical, physical, and biological stimuli, e.g., light, temperature, pH, magnetic/electric field, pressure, microorganisms, bacteria, viruses, toxic substances, and many others. This review concerns the newest achievements in the area of smart polymeric materials. The recent advances in the designing of stimuli-responsive polymers are described in this paper. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Soft Matter)

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17 pages, 5827 KB

Open AccessEditor’s ChoiceArticle

Hydrogen Embrittlement Detection Technology Using Nondestructive Testing for Realizing a Hydrogen Society

by Yamato Abiru, Hiroshi Nishiguchi, Masato Maekawa, Takara Nagata, Toshiya Itaya, Michie Koga and Toshiomi Nishi

Materials 2024, 17(17), 4237; https://doi.org/10.3390/ma17174237 - 27 Aug 2024

Cited by 4 | Viewed by 1820

Abstract

Crack detection in high-pressure hydrogen gas components, such as pipes, is crucial for ensuring the safety and reliability of hydrogen infrastructure. This study conducts the nondestructive testing of crack propagation in steel piping under cyclic compressive loads in the presence of hydrogen in [...] Read more.

Crack detection in high-pressure hydrogen gas components, such as pipes, is crucial for ensuring the safety and reliability of hydrogen infrastructure. This study conducts the nondestructive testing of crack propagation in steel piping under cyclic compressive loads in the presence of hydrogen in the material. The specimens were hydrogen-precharged through immersion in a 20 mass% ammonium thiocyanate solution at 40 °C for 72 h. The crack growth rate in hydrogen-precharged specimens was approximately 10 times faster than that in uncharged specimens, with cracks propagating from the inner to outer surfaces of the pipe. The fracture surface morphology differed significantly, with flat surfaces in hydrogen-precharged materials and convex or concave surfaces in uncharged materials. Eddy current and hammering tests revealed differences in the presence of large cracks between the two materials. By contrast, hammering tests revealed differences in the presence of a half size crack between the two materials. These findings highlight the effect of hydrogen precharging on crack propagation in steel piping and underscore the importance of early detection methods. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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23 pages, 4717 KB

Open AccessEditor’s ChoiceReview

Polysaccharide-Based Composite Systems in Bone Tissue Engineering: A Review

by Karina Niziołek, Dagmara Słota and Agnieszka Sobczak-Kupiec

Materials 2024, 17(17), 4220; https://doi.org/10.3390/ma17174220 - 27 Aug 2024

Cited by 10 | Viewed by 3083

Abstract

In recent years, a growing demand for biomaterials has been observed, particularly for applications in bone regenerative medicine. Bone tissue engineering (BTE) aims to develop innovative materials and strategies for repairing and regenerating bone defects and injuries. Polysaccharides, due to their biocompatibility, biodegradability [...] Read more.

In recent years, a growing demand for biomaterials has been observed, particularly for applications in bone regenerative medicine. Bone tissue engineering (BTE) aims to develop innovative materials and strategies for repairing and regenerating bone defects and injuries. Polysaccharides, due to their biocompatibility, biodegradability as well as bioactivity, have emerged as promising candidates for scaffolds or composite systems in BTE. Polymers combined with bioactive ceramics can support osteointegration. Calcium phosphate (CaP) ceramics can be a broad choice as an inorganic phase that stimulates the formation of new apatite layers. This review provides a comprehensive analysis of composite systems based on selected polysaccharides used in bone tissue engineering, highlighting their synthesis, properties and applications. Moreover, the applicability of the produced biocomposites has been analyzed, as well as new trends in modifying biomaterials and endowing them with new functionalizations. The effects of these composites on the mechanical properties, biocompatibility and osteoconductivity were critically analyzed. This article summarizes the latest manufacturing methods as well as new developments in polysaccharide-based biomaterials for bone and cartilage regeneration applications. Full article

(This article belongs to the Special Issue Bone Tissue Engineering Materials: From Preparation to Properties)

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12 pages, 3635 KB

Open AccessEditor’s ChoiceArticle

Finite Element Analysis of the Structure and Working Principle of Solid-State Shear Milling (S3M) Equipment

by Lingfei Wei, Chao Wang, Ruoxuan Duan, Zehang Zhou and Canhui Lu

Materials 2024, 17(17), 4210; https://doi.org/10.3390/ma17174210 - 26 Aug 2024

Cited by 1 | Viewed by 1392

Abstract

Solid-state shear milling (S3M) equipment is an evolution from traditional stone mills, enabling the processing of polymer materials and fillers through crushing, mixing, and mechanochemical reactions at ambient temperature. Due to the complex structure of the mill-pan, empirical data alone are insufficient to [...] Read more.

Solid-state shear milling (S3M) equipment is an evolution from traditional stone mills, enabling the processing of polymer materials and fillers through crushing, mixing, and mechanochemical reactions at ambient temperature. Due to the complex structure of the mill-pan, empirical data alone are insufficient to give a comprehensive understanding of the physicochemical interactions during the milling process. To provide an in-depth insight of the working effect and mechanism of S3M equipment, finite element method (FEM) analysis is employed to simulate the milling dynamics, which substantiates the correlation between numerical outcomes and experimental observations. A model simplification strategy is proposed to optimize calculation time without compromising accuracy. The findings in this work demonstrate the S-S bond breakage mechanism behind stress-induced devulcanization and suggest the structural optimizations for enhancing the devulcanization and pulverization efficiency of S3M equipment, thereby providing a theoretical foundation for its application in material processing. Full article

(This article belongs to the Special Issue Advances in Bio-Polymer and Polymer Composites)

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15 pages, 8923 KB

Open AccessEditor’s ChoiceArticle

Bio-Inspired Curved-Elliptical Lattice Structures for Enhanced Mechanical Performance and Deformation Stability

by Zhengmiao Guo, Fan Yang, Lingbo Li and Jiacheng Wu

Materials 2024, 17(17), 4191; https://doi.org/10.3390/ma17174191 - 24 Aug 2024

Cited by 6 | Viewed by 2825

Abstract

Lattice structures, characterized by their lightweight nature, high specific mechanical properties, and high design flexibility, have found widespread applications in fields such as aerospace and automotive engineering. However, the lightweight design of lattice structures often presents a trade-off between strength and stiffness. To [...] Read more.

Lattice structures, characterized by their lightweight nature, high specific mechanical properties, and high design flexibility, have found widespread applications in fields such as aerospace and automotive engineering. However, the lightweight design of lattice structures often presents a trade-off between strength and stiffness. To tackle this issue, a bio-inspired curved-elliptical (BCE) lattice is proposed to enhance the mechanical performance and deformation stability of three-dimensional lattice structures. BCE lattice specimens with different parameters were fabricated using selective laser melting (SLM) technology, followed by quasi-static compression tests. Finite element (FE) numerical simulations were also carried out for validation. The results demonstrate that the proposed BCE lattice structures exhibit stronger mechanical performance and more stable deformation modes that can be adjusted through parameter tuning. Specifically, by adjusting the design parameters, the BCE lattice structure can exhibit a bending-dominated delocalized deformation mode, avoiding catastrophic collapse during deformation. The specific energy absorption (SEA) can reach 24.6 J/g at a relative density of only 8%, with enhancements of 48.5% and 297.6% compared with the traditional energy-absorbing lattices Octet and body-center cubic (BCC), respectively. Moreover, the crushing force efficiency (CFE) of the BCE lattice structure surpasses those of Octet and BCC by 34.9% and 15.8%, respectively. Through a parametric study of the influence of the number of peaks N and the curve amplitude A on the compression performance of the BCE lattice structure, the compression deformation mechanism is further analyzed. The results indicate that the curve amplitude A and the number of peaks N have significant impacts on the deformation mode of the BCE lattice. By adjusting the parameters N and A, a structure with a combination of high energy absorption, high stiffness, and strong fracture resistance can be obtained, integrating the advantages of tensile-dominated and bending-dominated lattice structures. Full article

(This article belongs to the Special Issue Additive Manufacturing of Metallic Structures: Process and Applications)

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19 pages, 2385 KB

Open AccessEditor’s ChoiceArticle

Characterization and Modeling of Out-of-Plane Behavior of Fiber-Based Materials: Numerical Illustration of Wrinkle in Deep Drawing

by Cedric W. Sanjon, Yuchen Leng, Yi Yan, Peter Groche, Marek Hauptmann, Nicole Ludat and Jens-Peter Majschak

Materials 2024, 17(17), 4177; https://doi.org/10.3390/ma17174177 - 23 Aug 2024

Cited by 1 | Viewed by 1185

Abstract

The characterization and modeling of the out-of-plane behavior of fiber-based materials is essential for understanding their mechanical properties and improving their performance in various applications, especially in the forming process. Despite this, research on paper and paperboard has mainly focused on its in-plane [...] Read more.

The characterization and modeling of the out-of-plane behavior of fiber-based materials is essential for understanding their mechanical properties and improving their performance in various applications, especially in the forming process. Despite this, research on paper and paperboard has mainly focused on its in-plane behavior rather than its out-of-plane behavior. However, for accurate material characterization and modeling, it is critical to consider the out-of-plane behavior. In particular, delamination occurs during forming processes such as creasing, folding, and deep drawing. In this study, three material models for paperboard are presented: a single all-material continuum model and two composite models using different cohesion methods. The two composite models decouple in-plane and out-of-plane behavior and consist of continuum models describing the behavior of individual layers and cohesive interface models connecting the layers. Material characterization experiments are performed to derive the model parameters and verify the models. The models are validated using three-point bending and bulge tests and show good agreement. A case study is also conducted on the application of the three models in the simulation of a deep drawing process with respect to wrinkle formation. By comparing the simulation results of wrinkle formation in the deep drawing process, the composite models, especially the cohesive interface composite model, show greater accuracy in replicating the experimental results, indicating that a single continuum model can also be used to represent wrinkles. Full article

(This article belongs to the Section Materials Simulation and Design)

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11 pages, 4251 KB

Open AccessEditor’s ChoiceArticle

Evaluating Optical Properties of Mixed-Phase 2D MoSe₂/Poly(vinyl alcohol) Nanocomposite Film

by Suman Chhetri, Anh Tuan Nguyen, Nicolas Gaillard and Woochul Lee

Materials 2024, 17(17), 4178; https://doi.org/10.3390/ma17174178 - 23 Aug 2024

Cited by 1 | Viewed by 1238

Abstract

Highly solar light-absorbing poly(vinyl alcohol) (PVA) nanocomposite films have garnered wide attention in fields such as flexible optoelectronics, solar energy harvesting, and photothermal therapy. However, fabricating PVA nanocomposite films with a broad spectrum of solar absorption using cost-effective and non-toxic nanofillers remains challenging. [...] Read more.

Highly solar light-absorbing poly(vinyl alcohol) (PVA) nanocomposite films have garnered wide attention in fields such as flexible optoelectronics, solar energy harvesting, and photothermal therapy. However, fabricating PVA nanocomposite films with a broad spectrum of solar absorption using cost-effective and non-toxic nanofillers remains challenging. Herein, nanocomposite films of PVA incorporating various concentrations of mixed-phase 2D MoSe₂ nanosheets (i.e., a combination of the 2H and 1T phase) were prepared using a solution casting technique. Scanning electron microscopy (SEM) shows homogenous dispersion of MoSe₂ nanosheets in the PVA matrix even at higher concentrations, while atomic force microscopy (AFM) reveals increasing surface roughness with increasing MoSe₂ content, reaching a plateau after 20 wt%. With the increase in the concentration of MoSe₂, the nanocomposite films exhibit interesting light absorption characteristics reaching their highest absorption (average 94.9%) at 40 wt% MoSe₂. The incorporated mixed-phase MoSe₂ nanosheets induce a significant change in the energy levels of the PVA matrix, which is reflected in the reduced optical band gap energy (2.63 eV) at 40 wt% MoSe₂ against pure PVA (5.28 eV). The excellent light absorption of PVA nanocomposite films across the entire range from 250 nm to 2500 nm is attributed to the thin 2D structure of MoSe₂ and the presence of its mixed phase. Full article

(This article belongs to the Special Issue New Insight into Design and Properties of Nanomaterials (Second Edition))

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22 pages, 18002 KB

Open AccessEditor’s ChoiceArticle

Ultrasonic Cavitation Erosion Behavior of GX40CrNiSi25-20 Cast Stainless Steel through Yb-YAG Surface Remelting

by Daniela Cosma, Ion Mitelea, Ilare Bordeașu, Ion Dragoș Uțu and Corneliu Marius Crăciunescu

Materials 2024, 17(17), 4180; https://doi.org/10.3390/ma17174180 - 23 Aug 2024

Cited by 3 | Viewed by 1112

Abstract

Laser beam remelting is a relatively simple and highly effective technique for the physical modification of surfaces to improve resistance to cavitation erosion. In this study, we investigated the effect of laser remelting on the surface of cast stainless steel with 0.40% C, [...] Read more.

Laser beam remelting is a relatively simple and highly effective technique for the physical modification of surfaces to improve resistance to cavitation erosion. In this study, we investigated the effect of laser remelting on the surface of cast stainless steel with 0.40% C, 25% Cr, 20% Ni, and 1.5% Si on cavitation erosion behavior in tap water. The investigation was conducted using a piezoceramic crystal vibrator apparatus. Base laser beam parameters were carefully selected to result in a defect-free surface (no porosity, material burn, cracks) with hardness capable of generating better resistance to cavitation erosion. The experimental results were compared with those of the reference material. Surface morphology and microstructure evolution after cavitation tests were analyzed using an optical metallographic microscope (OM), scanning electron microscope (SEM), and hardness tests to explore the mechanism of improving surface degradation resistance. The conducted research demonstrated that surfaces modified by laser remelting exhibit a 4.8–5.1 times greater increase in cavitation erosion resistance due to the homogenization of chemical composition and refinement of the microstructure, while maintaining the properties of the base material. Full article

(This article belongs to the Special Issue Corrosion, Fatigue and Corrosion Protection of Metals and Their Alloys in Various Environments)

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11 pages, 4618 KB

Open AccessEditor’s ChoiceArticle

Modeling Study of Si₃N₄ Waveguides on a Sapphire Platform for Photonic Integration Applications

by Diandian Zhang, Shui-Qing Yu, Gregory J. Salamo, Richard A. Soref and Wei Du

Materials 2024, 17(16), 4148; https://doi.org/10.3390/ma17164148 - 22 Aug 2024

Cited by 17 | Viewed by 2947

Abstract

Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices [...] Read more.

Sapphire has various applications in photonics due to its broadband transparency, high-contrast index, and chemical and physical stability. Photonics integration on the sapphire platform has been proposed, along with potentially high-performance lasers made of group III–V materials. In parallel with developing active devices for photonics integration applications, in this work, silicon nitride optical waveguides on a sapphire substrate were analyzed using the commercial software Comsol Multiphysics in a spectral window of 800~2400 nm, covering the operating wavelengths of III–V lasers, which could be monolithically or hybridly integrated on the same substrate. A high confinement factor of ~90% near the single-mode limit was obtained, and a low bending loss of ~0.01 dB was effectively achieved with the bending radius reaching 90 μm, 70 μm, and 40 μm for wavelengths of 2000 nm, 1550 nm, and 850 nm, respectively. Furthermore, the use of a pedestal structure or a SiO₂ bottom cladding layer has shown potential to further reduce bending losses. The introduction of a SiO₂ bottom cladding layer effectively eliminates the influence of the substrate’s larger refractive index, resulting in further improvement in waveguide performance. The platform enables tightly built waveguides and small bending radii with high field confinement and low propagation losses, showcasing silicon nitride waveguides on sapphire as promising passive components for the development of high-performance and cost-effective PICs. Full article

(This article belongs to the Special Issue Thin Films, Nanostructures and Devices for Optoelectronics Applications)

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11 pages, 1960 KB

Open AccessEditor’s ChoiceArticle

Silicon Carbide Nanowire Based Integrated Electrode for High Temperature Supercapacitors

by Shiyu Sha, Chang Liang, Songyang Lv, Lin Xu, Defu Sun, Jiayue Yang, Lei Zhang and Shouzhi Wang

Materials 2024, 17(16), 4161; https://doi.org/10.3390/ma17164161 - 22 Aug 2024

Cited by 3 | Viewed by 1963

Abstract

Silicon carbide (SiC) single crystals have great prospects for high-temperature energy storage due to their robust structural stability, ultrahigh power output, and superior temperature stability. However, energy density is an essential challenge for SiC-based devices. Herein, a facile two-step strategy is proposed for [...] Read more.

Silicon carbide (SiC) single crystals have great prospects for high-temperature energy storage due to their robust structural stability, ultrahigh power output, and superior temperature stability. However, energy density is an essential challenge for SiC-based devices. Herein, a facile two-step strategy is proposed for the large-scale synthesis of a unique architecture of SiC nanowires incorporating MnO₂ for enhanced supercapacitors (SCs), arising from the synergy effect between the SiC nanowires as a highly conductive skeleton and the MnO₂ with numerous active sites. The SiC@MnO₂ integrated electrode-based SCs with ionic liquid (IL) electrolytes were assembled and delivered outstanding energy and power density, as well as a great lifespan at 150 °C. This impressive work offers a novel avenue for the practical application of SiC-based electrochemical energy storage devices with high energy density under high temperatures. Full article

(This article belongs to the Special Issue Research Progress of Advanced Crystals: Growth and Doping)

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15 pages, 6460 KB

Open AccessEditor’s ChoiceArticle

Evaluation of the Properties of 3D-Printed Onyx–Fiberglass Composites

by Jong-Hwan Yun, Gun-Woong Yoon, Yu-Jae Jeon and Min-Soo Kang

Materials 2024, 17(16), 4140; https://doi.org/10.3390/ma17164140 - 21 Aug 2024

Cited by 1 | Viewed by 2428

Abstract

This study evaluated the properties of 3D-printed Onyx–fiberglass composites. These composites were 3D-printed with zero, one, two, three, and four layers of fiberglass. Ten samples of each configuration were printed for the tensile and flexural tests. The average tensile strength of the Onyx [...] Read more.

This study evaluated the properties of 3D-printed Onyx–fiberglass composites. These composites were 3D-printed with zero, one, two, three, and four layers of fiberglass. Ten samples of each configuration were printed for the tensile and flexural tests. The average tensile strength of the Onyx specimens was calculated to be 44.79 MPa, which increased linearly by approximately 20–25 MPa with each additional fiberglass layer. The elastic moduli calculated from the micromechanics models were compared with the experimental values obtained from the tensile tests. The experimental elastic modulus increased more significantly than the model prediction when more fiberglass layers were added. The flexural modulus of Onyx was 17.6 GPa, which increased with each additional fiberglass layer. This quantitative analysis of composites fabricated using 3D printing highlights their potential for commercialization and industrial applications. Full article

(This article belongs to the Section Advanced Composites)

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18 pages, 10491 KB

Open AccessEditor’s ChoiceArticle

In Situ Synthesis of (Mo,Cr)Si₂ Composites by Spark Plasma Sintering

by Yue-Yao Wang and Guo-Hua Zhang

Materials 2024, 17(16), 4105; https://doi.org/10.3390/ma17164105 - 19 Aug 2024

Cited by 1 | Viewed by 1400

Abstract

This research investigated the impact of Cr content on the properties of (Mo,Cr)Si₂ composites. Composites with CrSi₂ molar fractions ranging from 0% to 10% were fabricated using spark plasma sintering (SPS). The study undertook a systematic analysis of the surface morphology, [...] Read more.

This research investigated the impact of Cr content on the properties of (Mo,Cr)Si₂ composites. Composites with CrSi₂ molar fractions ranging from 0% to 10% were fabricated using spark plasma sintering (SPS). The study undertook a systematic analysis of the surface morphology, phase composition, mechanical properties, and high-temperature oxidation resistance of the sintered samples across different compositions. Notably, the (Mo₉₅,Cr₅)Si₂ composite sintered at 1400 °C exhibited enhanced properties, including a Vickers hardness of 11.6 GPa, a fracture toughness of 4.6 MPa·m^1/2, and a flexural strength of 397 MPa. Upon oxidation at 1500 °C, the (Mo,Cr)Si₂ composites formed a protective oxide layer comprised of SiO₂ and Cr₂O₃. It was found that the generation and thickening of the protective oxide layer was promoted by the addition of moderate amounts of Cr to MoSi₂. Full article

(This article belongs to the Special Issue Sintering of Ceramic Materials)

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24 pages, 13126 KB

Open AccessEditor’s ChoiceArticle

Forced-Vibration Characteristics of Bowtie-Shaped Honeycomb Composite Sandwich Panel with Viscoelastic Damping Layer

by Siqi Miao, Yifeng Zhong, Mingtao Zhang and Rong Liu

Materials 2024, 17(16), 4067; https://doi.org/10.3390/ma17164067 - 16 Aug 2024

Cited by 3 | Viewed by 1466

Abstract

The incorporation of viscoelastic layers in laminates can markedly enhance the damped dynamic characteristics. This study focuses on integrating viscoelastic layers into the composite facesheet of the bowtie-shaped honeycomb core composite sandwich panel (BHC-CSP). The homogenization of the damped BHC-CSP is performed by [...] Read more.

The incorporation of viscoelastic layers in laminates can markedly enhance the damped dynamic characteristics. This study focuses on integrating viscoelastic layers into the composite facesheet of the bowtie-shaped honeycomb core composite sandwich panel (BHC-CSP). The homogenization of the damped BHC-CSP is performed by employing the variational asymptotic method. Based on the generalized total energy equation, the energy functional of the representative unit cell of the damped BHC-CSP is asymptotically analyzed. The warping function, derived following the principle of minimum potential energy, provides a basis for obtaining the corresponding Euler–Lagrange equation to ascertain the equivalent elastic properties of the damped BHC-CSP. Utilizing the developed two-dimensional equivalent model, the free-vibration characteristics of the damped BHC-CSP are examined across diverse boundary conditions while delving into the impact of an external viscous damping layer on the natural frequency of the damped BHC-CSP. The results reveal that intensified boundary constraints effectively diminish the effective vibration region of the damped BHC-CSP, thereby enhancing its overall stability. The introduction of a PMI foam layer proves effective in adjusting the stiffness and mass distribution of the damped BHC-CSP. Resonance characteristics are explored through frequency and time-domain analyses, highlighting the pivotal roles of the excitation position and receiver point in influencing the displacement and velocity responses. Although the stiffness is improved by incorporating a PMI foam layer, its effect on the damping performance of the damped BHC-CSP is minimal when compared to the T-SW308 foam layer. Full article

(This article belongs to the Section Advanced Composites)

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19 pages, 5935 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Towards the Reuse of Fire Retarded Polyamide 12 for Laser Sintering

by Dylan Seigler, Marcos Batistella and José-Marie Lopez-Cuesta

Materials 2024, 17(16), 4064; https://doi.org/10.3390/ma17164064 - 15 Aug 2024

Cited by 1 | Viewed by 1302

Abstract

The control of powder aging during Selective Laser Sintering (SLS) processing is one of the challenges to be overcome for the implementation of this technique in serial production. Aging phenomena, because of the elevated temperatures and long processing times, need to be considered [...] Read more.

The control of powder aging during Selective Laser Sintering (SLS) processing is one of the challenges to be overcome for the implementation of this technique in serial production. Aging phenomena, because of the elevated temperatures and long processing times, need to be considered when a fraction of the polymer powders present in the build chamber and not used to manufacture the parts are reused at various times. The aim of this study was to investigate the influence of successive reuse of blends of pure Polyamide 12 and its blends with two types of flame retardants (FR): ammonium polyphosphate (APP) and zinc borate (ZB). The composition of the blends was 70/30 (wt/wt) PA 12/FR. Four successive processing stages have been carried out by collecting the remaining powder blend each time. The powders were re-used using the same processing parameters after sieving. DSC measurements showed that the incorporation of FRs entailed a reduction in the processing window up to 4 °C; nevertheless, no further reduction was noted after aging. The TGA curves of aged blends of powders were also similar for pure PA 12 and PA 12 with FR. In addition, initial and reused powders presented a higher degree of crystallinity than the specimens processed from the powders. The heterogeneous character of the PA 12 after LS processing or reprocessing was shown through Pyrolysis Combustion Flow Calorimetry (PCFC) and cone calorimeter (CC) tests. FTIR analysis also showed that post-condensation reactions have occurred. The mode of action of the flame retardants was clearly seen on HRR curves at both tests. The first reuses of PA 12 powders entailed a significant reduction in time to ignition at the cone calorimeter (150 for the initial material to around 90 s for the reused material), indicating the formation of short polymer chains. Only in the case of zinc borate was it noticed that re-used powder was detrimental to the fire performance because of a strong increase in the value of pHRR (between 163 and 220 kW/m² for reused material instead of 125 kW/m² for the initial one). Full article

(This article belongs to the Special Issue Nonconventional Technology in Materials Processing-3rd Edition)

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27 pages, 6259 KB

Open AccessEditor’s ChoiceArticle

Real-Time Spectroscopic Ellipsometry for Flux Calibrations in Multi-Source Co-Evaporation of Thin Films: Application to Rate Variations in CuInSe₂ Deposition

by Dhurba R. Sapkota, Balaji Ramanujam, Puja Pradhan, Mohammed A. Razooqi Alaani, Ambalanath Shan, Michael J. Heben, Sylvain Marsillac, Nikolas J. Podraza and Robert W. Collins

Materials 2024, 17(16), 4048; https://doi.org/10.3390/ma17164048 - 14 Aug 2024

Cited by 1 | Viewed by 1327

Abstract

Flux calibrations in multi-source thermal co-evaporation of thin films have been developed based on real-time spectroscopic ellipsometry (RTSE) measurements. This methodology has been applied to fabricate CuInSe₂ (CIS) thin film photovoltaic (PV) absorbers, as an illustrative example, and their properties as functions [...] Read more.

Flux calibrations in multi-source thermal co-evaporation of thin films have been developed based on real-time spectroscopic ellipsometry (RTSE) measurements. This methodology has been applied to fabricate CuInSe₂ (CIS) thin film photovoltaic (PV) absorbers, as an illustrative example, and their properties as functions of deposition rate have been studied. In this example, multiple Cu layers are deposited step-wise onto the same Si wafer substrate at different Cu evaporation source temperatures (T_Cu). Multiple In₂Se₃ layers are deposited similarly at different In source temperatures (T_In). Using RTSE, the Cu and In₂Se₃ deposition rates are determined as functions of T_Cu and T_In. These rates, denoted R_eff, are measured in terms of effective thickness which is the volume per planar substrate area and accounts for surface roughness variations with deposition time. By assuming that all incident metal atoms are incorporated into the films and that the atomic concentrations in the deposited material components are the same as in single crystals, initial estimates of the Cu and In atom fluxes can be made versus T_Cu and T_In. Applying these estimates to the co-evaporation of a set of CIS films from individual Cu, In, and Se sources, atomic concentration corrections can be assigned to the Cu and In₂Se₃ calibration films. The corrections enable generation of a novel calibration diagram predicting the atomic ratio y = [Cu]/[In] and rate R_eff within the T_Cu-T_In plane. Using this diagram, optimization of the CIS properties as a PV absorber can be achieved versus both y and R_eff. Full article

(This article belongs to the Special Issue Advances in Thin Films Materials: Properties, Characterization, Physical Vapor Deposition and Application)

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11 pages, 3441 KB

Open AccessEditor’s ChoiceArticle

Enhancing Energy Storage Performance of 0.85Bi_0.5Na_0.5TiO₃-0.15LaFeO₃ Lead-Free Ferroelectric Ceramics via Buried Sintering

by Yixiao Zhang, Yuchen Jia, Jian Yang, Zixuan Feng, Shuohan Sun, Xiaolong Zhu, Haotian Wang, Shiguang Yan and Ming Zheng

Materials 2024, 17(16), 4019; https://doi.org/10.3390/ma17164019 - 13 Aug 2024

Cited by 5 | Viewed by 1730

Abstract

Bismuth sodium titanate (Bi_0.5Na_0.5TiO₃, BNT) ceramics are expected to replace traditional lead-based materials because of their excellent ferroelectric and piezoelectric characteristics, and they are widely used in the industrial, military, and medical fields. However, BNT ceramics have [...] Read more.

Bismuth sodium titanate (Bi_0.5Na_0.5TiO₃, BNT) ceramics are expected to replace traditional lead-based materials because of their excellent ferroelectric and piezoelectric characteristics, and they are widely used in the industrial, military, and medical fields. However, BNT ceramics have a low breakdown field strength, which leads to unsatisfactory energy storage performance. In this work, 0.85Bi_0.5Na_0.5TiO₃-0.15LaFeO₃ ceramics are prepared by the traditional high-temperature solid-phase reaction method, and their energy storage performance is greatly enhanced by improving the process of buried sintering. The results show that the buried sintering method can inhibit the formation of oxygen vacancy, reduce the volatilization of Bi₂O₃, and greatly improve the breakdown field strength of the ceramics so that the energy storage performance can be significantly enhanced. The breakdown field strength increases from 210 kV/cm to 310 kV/cm, and the energy storage density increases from 1.759 J/cm³ to 4.923 J/cm³. In addition, the energy storage density and energy storage efficiency of these ceramics have good frequency stability and temperature stability. In this study, the excellent energy storage performance of the ceramics prepared by the buried sintering method provides an effective idea for the design of lead-free ferroelectric ceramics with high energy storage performance and greatly expands its application field. Full article

(This article belongs to the Special Issue Ferroelectric, Magnetic, and Multiferroic Materials and Applications)

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11 pages, 2224 KB

Open AccessEditor’s ChoiceArticle

Color Stability of Various Orthodontic Clear Aligner Systems after Submersion in Different Staining Beverages

by Nicolae Daniel Olteanu, Ionut Taraboanta, Tinela Panaite, Carina Balcos, Sorana Nicoleta Rosu, Raluca Maria Vieriu, Stefania Dinu and Irina Nicoleta Zetu

Materials 2024, 17(16), 4009; https://doi.org/10.3390/ma17164009 - 12 Aug 2024

Cited by 4 | Viewed by 3503

Abstract

This study aimed to compare the color changes in two different orthodontic clear aligner systems after submersion in various beverages for 14 days. The tested aligner systems were Taglus Premium made of polyethylene terephthalate glycol (the TAG group) and CA^® Prodin+ made [...] Read more.

This study aimed to compare the color changes in two different orthodontic clear aligner systems after submersion in various beverages for 14 days. The tested aligner systems were Taglus Premium made of polyethylene terephthalate glycol (the TAG group) and CA^® Prodin+ made of a transparent copolyester and a thermoplastic elastomer (the PRO group). A total of 56 samples were firstly divided into two groups according to the tested system—TAG and PRO. Each group was subsequently divided in four subgroups according to immersion solution: A—artificial saliva, B—cola, C—coffee, D—red wine. Color measurements were performed on Days 1, 7 and 14 using a portable colorimeter and the CIE L*a*b* system. The obtained results showed significant color changes in both materials when exposed to coffee and red wine (p > 0.05). Samples in the PRO group showed a greater susceptibility to discoloration (higher ΔE values) when compared to the TAG group after submersion in cola (p = 0.025), coffee (p = 0.005) and red wine (p = 0.041) solutions. Statistical analysis revealed that all of the color parameters ΔL*, Δa*, Δb* and ΔE of both tested materials were affected by submersion in coffee solution for 14 days. In conclusion, the CA^® Pro+ aligner system is more prone to staining compared to the Taglus material after submersion for 14 days in cola, coffee and red wine solutions. Submersion for 14 days in coffee solution alters all of the color parameters (ΔL, Δa, Δb and ΔE) of both tested aligner materials. Full article

(This article belongs to the Special Issue Advanced Dental Materials: From Design to Application)

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30 pages, 3102 KB

Open AccessEditor’s ChoiceReview

Current Progress in Research into Environmentally Friendly Rigid Polyurethane Foams

by Sylwia Makowska, Dawid Szymborski, Natalia Sienkiewicz and Agnė Kairytė

Materials 2024, 17(16), 3971; https://doi.org/10.3390/ma17163971 - 9 Aug 2024

Cited by 8 | Viewed by 4082

Abstract

Polyurethane foams are materials characterized by low density and thermal conductivity and can therefore be used as thermal insulation materials. They are synthesized from toxic and environmentally unfriendly petrochemicals called isocyanates and polyols, which react with each other to form a urethane group [...] Read more.

Polyurethane foams are materials characterized by low density and thermal conductivity and can therefore be used as thermal insulation materials. They are synthesized from toxic and environmentally unfriendly petrochemicals called isocyanates and polyols, which react with each other to form a urethane group via the displacement of the movable hydrogen atom of the −OH group of the alcohol to the nitrogen atom of the isocyanate group. The following work describes the synthesis of polyurethane foams, focusing on using environmentally friendly materials, such as polyols derived from plant sources or modifiers, to strengthen the foam interface derived from plant precipitation containing cellulose derived from paper waste. The polyurethane foam industry is looking for new sources of materials to replace the currently used petrochemical products. The solutions described are proving to be an innovative and promising area capable of changing the face of current PU foam synthesis. Full article

(This article belongs to the Special Issue Polymers, Processing and Sustainability)

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23 pages, 5371 KB

Open AccessEditor’s ChoiceArticle

Low-Cycle Fatigue Properties of Bimetallic Steel Bar with Buckling: Energy-Based Numerical and Experimental Investigations

by Xuanyi Xue, Fei Wang, Neng Wang, Jianmin Hua and Wenjie Deng

Materials 2024, 17(16), 3974; https://doi.org/10.3390/ma17163974 - 9 Aug 2024

Cited by 4 | Viewed by 1193

Abstract

A bimetallic steel bar (BSB) consisting of stainless-steel cladding and carbon steel substrate exhibits excellent corrosion resistance and good mechanical properties. The bimetallic structure of BSBs may affect their low-cycle fatigue performance, and current investigations on the above issue are limited. In this [...] Read more.

A bimetallic steel bar (BSB) consisting of stainless-steel cladding and carbon steel substrate exhibits excellent corrosion resistance and good mechanical properties. The bimetallic structure of BSBs may affect their low-cycle fatigue performance, and current investigations on the above issue are limited. In this study, the low-cycle fatigue properties of bimetallic steel bars (BSBs) with inelastic buckling were investigated. Experiments and numerical studies were conducted to investigate the low-cycle fatigue capacity for BSBs, considering buckling. The buckling mode of BSBs is discussed. The hysteretic loops and energy properties of BSBs with various slenderness ratios (L/D) and fatigue strain amplitudes (ε_a) are investigated. With increases in the L/D and ε_a, the original symmetry for hysteresis loops disappears gradually, which is caused by the buckling. A predictive equation revealing the relation between the ε_a and fatigue life is suggested, which considers the effects of the L/D. A numerical modelling method is suggested to predict the hysteretic curves of BSBs. The effect of buckling on the stress and energy properties of BSBs is discussed through the numerical analysis of 44 models including the effects of the L/D, ε_a, and cladding ratios. The numerical analysis results illustrate that the hysteresis loops of BSBs with various ε_a values exhibit similar shapes. The increase in the cladding ratio reduces the peak stress and the dissipated energy properties of BSBs. The hysteresis loop energy density decreases by about 3% with an increase of 0.1 in the cladding ratio. It is recommended that the proportion of stainless steel inBSBs should be minimized once the corrosion resistance requirements are met. Full article

(This article belongs to the Special Issue Research Progress of the Fatigue, Crack and Failure Mechanisms of Materials and Structures)

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29 pages, 16855 KB

Open AccessEditor’s ChoiceArticle

Crashworthiness Performance and Multi-Objective Optimization of Bi-Directional Corrugated Tubes under Quasi-Static Axial Crushing

by Liuxiao Zou, Xin Wang, Ruojun Wang, Xin Huang, Menglei Li, Shuai Li, Zengyan Jiang and Weilong Yin

Materials 2024, 17(16), 3958; https://doi.org/10.3390/ma17163958 - 9 Aug 2024

Cited by 2 | Viewed by 1837

Abstract

Longitudinal corrugated tubes (LCTs) exhibit stable platform force under axial compression but have low specific energy absorption. Conversely, circumferential corrugated tubes (CCTs) offer higher specific energy absorption but with unstable platform force. To overcome these limitations, this paper introduces a novel bi-directional corrugated [...] Read more.

Longitudinal corrugated tubes (LCTs) exhibit stable platform force under axial compression but have low specific energy absorption. Conversely, circumferential corrugated tubes (CCTs) offer higher specific energy absorption but with unstable platform force. To overcome these limitations, this paper introduces a novel bi-directional corrugated tube (BCT) that amalgamates the strengths of both the CCT and LCT while mitigating their weaknesses. The BCT is formed by rolling a bi-directional corrugated structure into a circular tubular form. Numerical simulations of the BCT closely align with experimental results. The study further examines the influence of discrete parameters on the BCT’s performance through simulations and identifies the tube’s optimal design using the integral entropy TOPSIS method. A full factorial experimental approach is then employed to investigate the impact of radial amplitude, axial amplitude, and neutral surface diameter on the crushing behavior of the BCT, comparing it with the CCT and LCT. The results reveal that increasing

A_{i}

enhances the axial resistance of the structure, while increasing

A_{j}

reduces the buckling effect, resulting in a higher specific energy absorption and lower ultimate load capacity for the BCT compared to the CCT and LCT. A simultaneous multi-objective optimization of the CCT, LCT, and BCT confirms that the BCT offers superior specific energy absorption and ultimate load capacity. The optimal configuration parameters for the BCT have been determined, providing significant insights for practical applications in crashworthiness engineering. Full article

(This article belongs to the Special Issue Advances in Modelling and Simulation of Materials in Applied Sciences)

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47 pages, 4047 KB

Open AccessEditor’s ChoiceReview

Polydopamine Applications in Biomedicine and Environmental Science

by Hossein Omidian and Renae L. Wilson

Materials 2024, 17(16), 3916; https://doi.org/10.3390/ma17163916 - 7 Aug 2024

Cited by 11 | Viewed by 4985

Abstract

This manuscript explores the multifaceted applications of polydopamine (PDA) across various scientific and industrial domains. It covers the chemical aspects of PDA and its potential in bone tissue engineering, implant enhancements, cancer treatment, and nanotechnology. The manuscript investigates PDA’s roles in tissue engineering, [...] Read more.

This manuscript explores the multifaceted applications of polydopamine (PDA) across various scientific and industrial domains. It covers the chemical aspects of PDA and its potential in bone tissue engineering, implant enhancements, cancer treatment, and nanotechnology. The manuscript investigates PDA’s roles in tissue engineering, cell culture technologies, surface modifications, drug delivery systems, and sensing techniques. Additionally, it highlights PDA’s contributions to microfabrication, nanoengineering, and environmental applications. Through detailed testing and assessment, the study identifies limitations in PDA-related research, such as synthesis complexity, incomplete mechanistic understanding, and biocompatibility variability. It also proposes future research directions aimed at improving synthesis techniques, expanding biomedical applications, and enhancing sensing technologies to optimize PDA’s efficacy and scalability. Full article

(This article belongs to the Special Issue Latest Advances in Functional Polymeric Materials for Environmental and Biomedical Applications)

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14 pages, 4592 KB

Open AccessEditor’s ChoiceArticle

Compressive Properties and Energy Absorption Characteristics of Co-Continuous Interlocking PDMS/PLA Lattice Composites

by Han Wang, Kedi Wang, Jincheng Lei and Xueling Fan

Materials 2024, 17(16), 3894; https://doi.org/10.3390/ma17163894 - 6 Aug 2024

Cited by 2 | Viewed by 1644

Abstract

Co-continuous interlocking lattice structures usually present superior compressive properties and energy absorption characteristics. In this study, co-continuous interlocking polydimethylsiloxane/polylactic acid (PDMS/PLA) lattice composites were designed with different strut diameters, and successfully manufactured by combining the fused deposition modeling (FDM) technique and the infiltration [...] Read more.

Co-continuous interlocking lattice structures usually present superior compressive properties and energy absorption characteristics. In this study, co-continuous interlocking polydimethylsiloxane/polylactic acid (PDMS/PLA) lattice composites were designed with different strut diameters, and successfully manufactured by combining the fused deposition modeling (FDM) technique and the infiltration method. This fabrication method can realize the change and control of structure parameters. The effects of the strut diameter on the compressive properties and energy absorption behavior of PDMS/PLA lattice composites were investigated by using quasi-static compression tests. The compressive properties of the co-continuous interlocking PDMS/PLA lattice composites can be adjusted in a narrow density range by a linear correlation. The energy absorption density of the co-continuous interlocking PDMS/PLA lattice composites increases with the increase in the PLA strut diameter and presents a higher efficiency peak and wider plateau region. The PLA lattice acts as a skeleton and plays an important role in bearing the compressive load and in energy absorption. The indexes of the compressive properties/energy absorption characteristics and PLA volume fraction of co-continuous interlocking PDMS/PLA lattice composites show linear relationships in logarithmic coordinates. The effect of the PLA volume fraction increasing on the plateau stress is more sensitive than the compressive strength and energy absorption density. Full article

(This article belongs to the Special Issue Advances in Structural Design and Numerical Modelling of Composite Materials)

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17 pages, 5617 KB

Open AccessEditor’s ChoiceArticle

Impact of Thermochemical Treatments on Electrical Conductivity of Donor-Doped Strontium Titanate Sr(Ln)TiO₃ Ceramics

by Aleksandr Bamburov, Ekaterina Kravchenko and Aleksey A. Yaremchenko

Materials 2024, 17(15), 3876; https://doi.org/10.3390/ma17153876 - 5 Aug 2024

Viewed by 1674

Abstract

The remarkable stability, suitable thermomechanical characteristics, and acceptable electrical properties of donor-doped strontium titanates make them attractive materials for fuel electrodes, interconnects, and supports of solid oxide fuel and electrolysis cells (SOFC/SOEC). The present study addresses the impact of processing and thermochemical treatment [...] Read more.

The remarkable stability, suitable thermomechanical characteristics, and acceptable electrical properties of donor-doped strontium titanates make them attractive materials for fuel electrodes, interconnects, and supports of solid oxide fuel and electrolysis cells (SOFC/SOEC). The present study addresses the impact of processing and thermochemical treatment conditions on the electrical conductivity of SrTiO₃-derived ceramics with moderate acceptor-type substitution in a strontium sublattice. A-site-deficient Sr_0.85La_0.10TiO_3−δ and cation-stoichiometric Sr_0.85Pr_0.15TiO_3+δ ceramics with varying microstructures and levels of reduction have been prepared and characterized by XRD, SEM, TGA, and electrical conductivity measurements under reducing conditions. The analysis of the collected data suggested that the reduction process of dense donor-doped SrTiO₃ ceramics is limited by sluggish oxygen diffusion in the crystal lattice even at temperatures as high as 1300 °C. A higher degree of reduction and higher electrical conductivity can be obtained for porous structures under similar thermochemical treatment conditions. Metallic-like conductivity in dense reduced Sr_0.85La_0.10TiO_3−δ corresponds to the state quenched from the processing temperature and is proportional to the concentration of Ti³⁺ in the lattice. Due to poor oxygen diffusivity in the bulk, dense Sr_0.85La_0.10TiO_3−δ ceramics remain redox inactive and maintain a high level of conductivity under reducing conditions at temperatures below 1000 °C. While the behavior and properties of dense reduced Sr_0.85Pr_0.15TiO_3+δ ceramics with a large grain size (10–40 µm) were found to be similar, decreasing grain size down to 1–3 µm results in an increasing role of resistive grain boundaries which, regardless of the degree of reduction, determine the semiconducting behavior and lower total electrical conductivity of fine-grained Sr_0.85Pr_0.15TiO_3+δ ceramics. Oxidized porous Sr_0.85Pr_0.15TiO_3+δ ceramics exhibit faster kinetics of reduction compared to the Sr_0.85La_0.10TiO_3−δ counterpart at temperatures below 1000 °C, whereas equilibration kinetics of porous Sr_0.85La_0.10TiO_3−δ structures can be facilitated by reductive pre-treatments at elevated temperatures. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Chemistry)

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28 pages, 16553 KB

Open AccessEditor’s ChoiceReview

Progress in Additive Manufacturing of Magnesium Alloys: A Review

by Jiayu Chen and Bin Chen

Materials 2024, 17(15), 3851; https://doi.org/10.3390/ma17153851 - 3 Aug 2024

Cited by 27 | Viewed by 6809

Abstract

Magnesium alloys, renowned for their lightweight yet high-strength characteristics, with exceptional mechanical properties, are highly coveted for numerous applications. The emergence of magnesium alloy additive manufacturing (Mg AM) has further propelled their popularity, offering advantages such as unparalleled precision, swift production rates, enhanced [...] Read more.

Magnesium alloys, renowned for their lightweight yet high-strength characteristics, with exceptional mechanical properties, are highly coveted for numerous applications. The emergence of magnesium alloy additive manufacturing (Mg AM) has further propelled their popularity, offering advantages such as unparalleled precision, swift production rates, enhanced design freedom, and optimized material utilization. This technology holds immense potential in fabricating intricate geometries, complex internal structures, and performance-tailored microstructures, enabling groundbreaking applications. In this paper, we delve into the core processes and pivotal influencing factors of the current techniques employed in Mg AM, including selective laser melting (SLM), electron beam melting (EBM), wire arc additive manufacturing (WAAM), binder jetting (BJ), friction stir additive manufacturing (FSAM), and indirect additive manufacturing (I-AM). Laser powder bed fusion (LPBF) excels in precision but is limited by a low deposition rate and chamber size; WAAM offers cost-effectiveness, high efficiency, and scalability for large components; BJ enables precise material deposition for customized parts with environmental benefits; FSAM achieves fine grain sizes, low defect rates, and potential for precision products; and I-AM boasts a high build rate and industrial adaptability but is less studied recently. This paper attempts to explore the possibilities and challenges for future research in AM. Among them, two issues are how to mix different AM applications and how to use the integration of Internet technologies, machine learning, and process modeling with AM, which are innovative breakthroughs in AM. Full article

(This article belongs to the Special Issue 3D Printing Technology with Metal Materials)

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15 pages, 6045 KB

Open AccessEditor’s ChoiceArticle

Rheological Changes in Bio-Based Filaments Induced by Extrusion-Based 3D Printing Process

by Antonella Patti and Stefano Acierno

Materials 2024, 17(15), 3839; https://doi.org/10.3390/ma17153839 - 2 Aug 2024

Cited by 4 | Viewed by 1906

Abstract

In this work, the authors investigated the impact of extrusion-based printing process on the structural characteristics of bio-based resins through rheological measurements. Two commercially available filaments made from unfilled and wood-filled polylactide (PLA) polymers were considered. Three-dimensional specimens were prepared by printing these [...] Read more.

In this work, the authors investigated the impact of extrusion-based printing process on the structural characteristics of bio-based resins through rheological measurements. Two commercially available filaments made from unfilled and wood-filled polylactide (PLA) polymers were considered. Three-dimensional specimens were prepared by printing these filaments under various operating conditions, i.e., changing the extruder temperature and printing rate, and examined using time sweep tests. Specific cycle rheological testing was conducted on pelletized filaments to simulate temperature changes in the printing process. The rheological characteristics of unprocessed materials, in terms of storage (G′) and loss (G″) moduli, were found to be slightly affected by temperature changes. For a pure polymer, the G′ slope at a low frequency decreased over time, showing that the polymer chains evolved from a higher to a lower molecular weight. For wood-filled materials, the G′ slope rose over the testing time, emphasizing the formation of a percolated network of structured filler within the matrix. On the other side, the rheological parameters of both materials were strongly impacted by the printing extrusion and the related conditions. At lower nozzle temperatures (200 °C), by decreasing the printing speed, the G′ and G″ curves became increasingly different with respect to unprocessed resin; whereas at higher nozzle temperatures (220 °C), the influence of the printing speed was insignificant, and all curves (albeit distant from those of unprocessed matrix) mainly overlapped. Considerations on degradation kinetics of both materials during the printing process were also provided by fitting experimental data of complex viscosity with linear correlation over time. Full article

(This article belongs to the Special Issue Polymers, Processing and Sustainability)

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28 pages, 17468 KB

Open AccessEditor’s ChoiceArticle

Characterisation of Large-Sized REBaCuO Bulks for Application in Flux Modulation Machines

by Quentin Nouailhetas, Yiteng Xing, Rémi Dorget, Walid Dirahoui, Santiago Guijosa, Frederic Trillaud, Jean Lévêque, Jacques Guillaume Noudem, Julien Labbé and Kévin Berger

Materials 2024, 17(15), 3827; https://doi.org/10.3390/ma17153827 - 2 Aug 2024

Cited by 3 | Viewed by 1245

Abstract

High temperature superconductors (HTSs) are enablers of extensive electrification for aircraft propulsion. Indeed, if used in electrical machines, HTS materials can drastically improve their performance in terms of the power-to-weight ratio. Among the different topologies of superconducting electrical machines, a flux modulation machine [...] Read more.

High temperature superconductors (HTSs) are enablers of extensive electrification for aircraft propulsion. Indeed, if used in electrical machines, HTS materials can drastically improve their performance in terms of the power-to-weight ratio. Among the different topologies of superconducting electrical machines, a flux modulation machine based on HTS bulks is of interest for its compactness and light weight. Such a machine is proposed in the FROST (Flux-barrier Rotating Superconducting Topology) project led by Airbus to develop new technologies as part of their decarbonization goals driven by international policies. The rotor of the machine will house large ring-segment-shaped HTS bulks in order to increase the output power. However, the properties of those bulks are scarcely known and have barely been investigated in the literature. In this context, the present work aims to fill out partially this scarcity within the framework of FROST. Thus, a thorough characterisation of the performances and homogeneity of 11 large REBaCuO bulks was carried out. Ten of the bulks are to be utilized in the machine prototype, originally keeping the eleventh bulk as a spare. A first set of characterisation was conducted on the eleven bulks. For this set, the trapped field mapping and the critical current were estimated. Then, a series of in-depth characterisations on the eleventh bulk followed. It included critical current measurement, X-ray diffraction, and scanning electron microscopy on different millimetre-size samples cut out from the bulk at various locations. The X-ray diffraction and scanning electron microscopy showed weakly oxygenated regions inside the bulk explaining the local drop or loss in superconducting properties. The objective was to determine the causes of the inhomogeneities found in the trapped field measured on all the bulks, sacrificing one of them, here the spare one. To help obtain a clearer picture, a numerical model was then elaborated to reproduce the field map of the eleventh bulk using the experimental data obtained from the characterisation of its various small samples. It is concluded that further characterisations, including the statistics on various bulks, are still needed to understand the underlying reasons for inhomogeneity in the trapped field. Nonetheless, all the bulks presented enough current density to be usable in the construction of the proposed machine. Full article

(This article belongs to the Special Issue Characterization and Application of Superconducting Materials)

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17 pages, 5227 KB

Open AccessEditor’s ChoiceArticle

Experimental Study on Preparation of Inorganic Fibers from Circulating Fluidized Bed Boilers Ash

by Qingjia Wang, Tuo Zhou, Zhiao Li, Yi Ding, Qiang Song, Man Zhang, Nan Hu and Hairui Yang

Materials 2024, 17(15), 3800; https://doi.org/10.3390/ma17153800 - 1 Aug 2024

Cited by 3 | Viewed by 1093

Abstract

The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach [...] Read more.

The ash generated by Circulating Fluidized Bed (CFB) boilers is featured by its looseness and porosity, low content of glassy substances, and high contents of calcium (Ca) and sulfur (S), thus resulting in a low comprehensive utilization rate. Currently, the predominant treatment approach for CFB ash and slag is stacking, which may give rise to issues like environmental pollution. In this paper, CFB ash (with a CaO content of 7.64% and an SO₃ content of 1.77%) was used as the main raw material. The high-temperature melting characteristics, viscosity–temperature characteristics, and initial crystallization temperature of samples with different acidity coefficients were investigated. The final drawing temperature range of the samples was determined, and mechanical property tests were conducted on the prepared inorganic fibers. The results show that the addition of dolomite powder has a significant reducing effect on the complete liquid phase temperature. The final drawing temperatures of the samples with different acidity coefficients range as follows: 1270–1318 °C; 1272–1351 °C; 1250–1372 °C; 1280–1380 °C; 1300–1382 °C; and 1310–1384 °C. The drawing temperature of this system is slightly lower than that of basalt fibers. Based on the test results of the mechanical properties of inorganic fibers, the Young’s modulus of the inorganic fibers prepared through the experiment lies between 55 GPa and 74 GPa, which basically meets the performance requirements of inorganic fibers. Consequently, the method of preparing inorganic fibers by using CFB ash and dolomite powder is entirely feasible. Full article

(This article belongs to the Special Issue Obtaining and Characterization of New Materials (5th Edition))

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24 pages, 8184 KB

Open AccessEditor’s ChoiceArticle

A Comparative Analysis of Friction and Energy Losses in Hydrogen and CNG Fueled Engines: Implications on the Top Compression Ring Design Using Steel, Cast Iron, and Silicon Nitride Materials

by Vasiliki-Ioanna Nikolopoulou, Anastasios Zavos and Pantelis Nikolakopoulos

Materials 2024, 17(15), 3806; https://doi.org/10.3390/ma17153806 - 1 Aug 2024

Cited by 1 | Viewed by 2050

Abstract

Optimizing the design of the top compression ring holds immense importance in reducing friction across both traditional Internal Combustion (IC) engines and hybrid power systems. This study investigates the impact of alternative fuels, specifically hydrogen and CNG, on the behavior of top piston [...] Read more.

Optimizing the design of the top compression ring holds immense importance in reducing friction across both traditional Internal Combustion (IC) engines and hybrid power systems. This study investigates the impact of alternative fuels, specifically hydrogen and CNG, on the behavior of top piston rings within internal combustion (IC) engines. The goal of this approach is to understand the complex interplay between blow-by, fuel type, material behavior, and their effects on ring friction, energy losses, and resulting ring strength. Two types of IC engines were analyzed, taking into account flow conditions derived from in-cylinder pressures and piston geometry. Following ISO 6622-2:2013 guidelines, thick top compression rings made from varying materials (steel, cast iron, and silicon nitride) were investigated and compared. Through a quasi-static ring model within Computational Fluid Dynamics (CFD), critical tribological parameters such as the minimum film and ring friction were simulated, revealing that lighter hydrogen-powered engines with higher combustion pressures could potentially experience approximately 34.7% greater power losses compared to their heavier CNG counterparts. By delving into the interaction among the fuel delivery system, gas blow-by, and material properties, this study unveils valuable insights into the tribological and structural behavior of the top piston ring conjunction. Notably, the silicon nitride material demonstrates promising strength improvements, while the adoption of Direct Injection (DI) is associated with approximately 10.1% higher energy losses compared to PFI. Such findings carry significant implications for enhancing engine efficiency and promoting sustainable energy utilization. Full article

(This article belongs to the Special Issue Advances in Tribological and Other Functional Properties of Materials)

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15 pages, 18031 KB

Open AccessEditor’s ChoiceArticle

Tribological Research of Resin Composites with the Fillers of Glass Powder and Micro-Bubbles

by Juozas Padgurskas, Vitoldas Vilčinskas, Muhammad Ibnu Rashyid, Muhammad Akhsin Muflikhun, Raimundas Rukuiža and Aušra Selskienė

Materials 2024, 17(15), 3764; https://doi.org/10.3390/ma17153764 - 31 Jul 2024

Cited by 4 | Viewed by 1575

Abstract

This study investigates the tribological properties of resin composites reinforced with the fillers of glass powder and micro-bubbles. Resin composites were prepared with varying concentrations from 1% to 5% wt of fillers. Tribological tests were conducted using a block-on-ring scheme under dry friction [...] Read more.

This study investigates the tribological properties of resin composites reinforced with the fillers of glass powder and micro-bubbles. Resin composites were prepared with varying concentrations from 1% to 5% wt of fillers. Tribological tests were conducted using a block-on-ring scheme under dry friction conditions. The measurements of friction coefficient and wear values were performed under variable rotation speeds and loading conditions. The study showed that resin composites with 2–3% glass powder fillers and resin composites with 3–4% micro-bubbles exhibited optimal tribological properties. The resin glass powder modifications reduce the wear by 63% and resin micro-bubbles reduce wear by 32%. SEM analysis of the surfaces revealed surface imperfections and structural damage mechanisms, including abrasive and fatigue wear. The study concludes that specific filler concentrations improve the friction and wear resistance of resin composites, highlighting the importance of material preparation and surface quality in tribological performance. The increased wear resistance on both composites would hopefully expand the usage of additive manufactured composite, namely industrial moving components such as polymer gear, wheel, pulley, etc. Full article

(This article belongs to the Special Issue Advances in Tribological and Other Functional Properties of Materials)

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15 pages, 7883 KB

Open AccessEditor’s ChoiceArticle

A Two-Layer Graphene Nonwoven Fabric for Effective Electromagnetic Interference Shielding

by Ying Wu, Haijun Tang, Liying Kang, Hongfu Li and Naisheng Jiang

Materials 2024, 17(15), 3747; https://doi.org/10.3390/ma17153747 - 29 Jul 2024

Viewed by 1496

Abstract

Rapid advancements and proliferation of electronic devices in the past decades have significantly intensified electromagnetic interference (EMI) issues, driving the demand for more effective shielding materials. Herein, we introduce a novel two-layer graphene nonwoven fabric (2-gNWF) that shows excellent EMI shielding properties. The [...] Read more.

Rapid advancements and proliferation of electronic devices in the past decades have significantly intensified electromagnetic interference (EMI) issues, driving the demand for more effective shielding materials. Herein, we introduce a novel two-layer graphene nonwoven fabric (2-gNWF) that shows excellent EMI shielding properties. The 2-gNWF fabric comprises a porous fibrous upper layer and a dense conductive film-like lower layer, specifically designed to enhance EMI shielding through the combined mechanisms of reflection, multiple internal reflections, and absorption of electromagnetic waves. The 2-gNWF exhibits a remarkable EMI shielding effectiveness (SE) of 80 dB while maintaining an impressively low density of 0.039 g/cm³, surpassing the performance of many existing graphene-based materials. The excellent EMI shielding performance of 2-gNWF is attributed to the multiple interactions of incident electromagnetic waves with its highly conductive network and porous structure, leading to efficient energy dissipation. The combination of high EMI SE and low density makes 2-gNWF ideal for applications that require lightweight yet effective shielding properties, demonstrating the significant potential for advanced EMI shielding applications. Full article

(This article belongs to the Special Issue Carbon Nanomaterials for Multifunctional Applications)

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12 pages, 3470 KB

Open AccessEditor’s ChoiceArticle

Facilely Promoting the Concentration of Baicalin in Polylactic Acid Fiber for UV Shielding and Antibacterial Functions: A Customized and Sustainable Approach

by Yuyang Zhou, Peng Deng and Wei Chen

Materials 2024, 17(15), 3734; https://doi.org/10.3390/ma17153734 - 28 Jul 2024

Cited by 3 | Viewed by 1650

Abstract

There is a significant trend towards the integration of natural substances with bio-polymers for fully bio-based functional composites. Polylactic acid is regarded as a promising biodegradable polymer for replacing synthetic polymers. Differing from the case of natural fiber, the incompatibility of polylactic acid [...] Read more.

There is a significant trend towards the integration of natural substances with bio-polymers for fully bio-based functional composites. Polylactic acid is regarded as a promising biodegradable polymer for replacing synthetic polymers. Differing from the case of natural fiber, the incompatibility of polylactic acid with bio-based molecules prevents it from being used to fabricate high-quality sustainable composites. This work presents a simultaneous ultraviolet shielding and antibacterial finishing process of polylactic acid combined with bioactive baicalin and an eco-friendly ester, which is highlighted for (a) the lack of synthetic chemicals involved in such process, (b) adsorption enhancement achieved at a mild temperature, and (c) marginal color change on treated polylactic acid. A response surface methodology was adopted to analyze the impacts of various factors on the baicalin quantity in polylactic acid, and to optimize the treatment condition. The uptake ratio of baicalin in polylactic acid was drastically promoted from 8.5 mg/g to 21.1 mg/g using methyl cinnamate. The response surface methodology based on a central composite design experiment indicated that the usage of baicalin was the most significant factor followed by methyl cinnamate and temperature. After optimization, a very faint color depth of 1.2 was apparent, but UPF 50+ and 92% bacterial reduction could be achieved. In all, the success in strengthening of the functionalities of polylactic acid extends the applications of polylactic acid products. Full article

(This article belongs to the Special Issue Advances in the Sustainable Fabrication of Smart and Functional Textiles)

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20 pages, 2693 KB

Open AccessEditor’s ChoiceReview

Advanced Material Strategy for Restoring Damaged Endodontically Treated Teeth: A Comprehensive Review

by Elisa Caussin, Mathieu Izart, Romain Ceinos, Jean-Pierre Attal, Fleur Beres and Philippe François

Materials 2024, 17(15), 3736; https://doi.org/10.3390/ma17153736 - 28 Jul 2024

Cited by 20 | Viewed by 11236

Abstract

The restoration of endodontically treated teeth (ETT) remains a significant challenge in modern dentistry. These teeth often suffer from substantial structural damage due to both the original pathology and the invasive nature of endodontic procedures. Consequently, ETT are more susceptible to fractures compared [...] Read more.

The restoration of endodontically treated teeth (ETT) remains a significant challenge in modern dentistry. These teeth often suffer from substantial structural damage due to both the original pathology and the invasive nature of endodontic procedures. Consequently, ETT are more susceptible to fractures compared to vital teeth, necessitating restorative strategies that can effectively restore both function and aesthetics while minimizing the risk of failure. In recent years, advances in adhesive dentistry and the development of high-strength ceramics have further expanded the restorative options for ETT. Bonded restorations have gained popularity as they preserve more tooth structure and enhance the overall strenght of the tooth-restoration complex. The choice of restorative material and technique is influenced by numerous factors, including the amount of remaining tooth structure, the functional requirements of the tooth, and the aesthetic demands of the patient. Despite the plethora of available materials and techniques, the optimal approach to restoring ETT remains a topic of ongoing research and debate. In this comprehensive review, the current state of and recent advances in restoring damaged endodontically treated teeth are explored. Numerous therapeutic options exist, involving a wide range of materials. This article aims to present the biomaterial advancements of the past decade and their applications, offering alternative approaches to treating damaged ETT with the goal of prolonging their retention on the dental arch and serving as a valuable resource for dental practitioners who face this issue daily. Full article

(This article belongs to the Section Polymeric Materials)

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29 pages, 3983 KB

Open AccessEditor’s ChoiceReview

Polymer Materials for Optoelectronics and Energy Applications

by Ju Won Lim

Materials 2024, 17(15), 3698; https://doi.org/10.3390/ma17153698 - 26 Jul 2024

Cited by 27 | Viewed by 4200

Abstract

This review comprehensively addresses the developments and applications of polymer materials in optoelectronics. Especially, this review introduces how the materials absorb, emit, and transfer charges, including the exciton–vibrational coupling, nonradiative and radiative processes, Förster Resonance Energy Transfer (FRET), and energy dynamics. Furthermore, it [...] Read more.

This review comprehensively addresses the developments and applications of polymer materials in optoelectronics. Especially, this review introduces how the materials absorb, emit, and transfer charges, including the exciton–vibrational coupling, nonradiative and radiative processes, Förster Resonance Energy Transfer (FRET), and energy dynamics. Furthermore, it outlines charge trapping and recombination in the materials and draws the corresponding practical implications. The following section focuses on the practical application of organic materials in optoelectronics devices and highlights the detailed structure, operational principle, and performance metrics of organic photovoltaic cells (OPVs), organic light-emitting diodes (OLEDs), organic photodetectors, and organic transistors in detail. Finally, this study underscores the transformative impact of organic materials on the evolution of optoelectronics, providing a comprehensive understanding of their properties, mechanisms, and diverse applications that contribute to advancing innovative technologies in the field. Full article

(This article belongs to the Special Issue Research on New Optoelectronic Materials and Devices)

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