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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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35 pages, 5269 KiB  
Article
The Quantum Transport of Dirac Fermions in Selected Graphene Nanosystems Away from the Charge Neutrality Point
by Adam Rycerz
Materials 2025, 18(9), 2036; https://doi.org/10.3390/ma18092036 - 29 Apr 2025
Viewed by 450
Abstract
The peculiar electronic properties of graphene, including the universal dc conductivity and the pseudodiffusive shot noise, are usually found in a small vicinity close to the charge neutrality point, away from which the electron’s effective mass raises, and nanostructures in graphene start to [...] Read more.
The peculiar electronic properties of graphene, including the universal dc conductivity and the pseudodiffusive shot noise, are usually found in a small vicinity close to the charge neutrality point, away from which the electron’s effective mass raises, and nanostructures in graphene start to behave similarly to familiar Sharvin contacts in semiconducting heterostructures. Recently, it was pointed out that as long as abrupt potential steps separate the sample area from the leads, some graphene-specific features can be identified relatively far from the charge neutrality point. These features include greater conductance reduction and shot noise enhancement compared to the standard Sharvin values. The purpose of this paper is twofold: First, we extend the previous analysis based on the effective Dirac equation, and derive the formulas that allow the calculation of the arbitrary charge transfer cumulant for doped graphene. Second, the results of the analytic considerations are compared with numerical simulations of quantum transport on the honeycomb lattice for selected nanosystems for which considerations starting from the Dirac equation cannot be directly adapted. For a wedge-shaped constriction with zigzag edges, the transport characteristics can be tuned from graphene-specific (sub-Sharvin) values to standard Sharvin values by varying the electrostatic potential profile in the narrowest section. A similar scenario is followed by the half-Corbino disk. In contrast, a circular quantum dot with two narrow openings showing a mixed behavior appears: the conductance is close to the Sharvin value, while the Fano factor approaches the value characterizing the symmetric chaotic cavity. Carving a hole in the quantum dot to eliminate direct trajectories between the openings reduces the conductance to sub-Sharvin value, but the Fano factor is unaffected. Our results suggest that experimental attempts to verify the predictions for the sub-Sharvin transport regime should focus on systems with relatively wide openings, where the scattering at the sample edges is insignificant next to the scattering at the sample–lead interfaces. Full article
(This article belongs to the Special Issue Quantum Transport in Novel 2D Materials and Structures)
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15 pages, 3554 KiB  
Article
Study of ZrO2 Gate Dielectric with Thin SiO2 Interfacial Layer in 4H-SiC Trench MOS Capacitors
by Qimin Huang, Yunduo Guo, Anfeng Wang, Zhaopeng Bai, Lin Gu, Zhenyu Wang, Chengxi Ding, Yi Shen, Hongping Ma and Qingchun Zhang
Materials 2025, 18(8), 1741; https://doi.org/10.3390/ma18081741 - 10 Apr 2025
Viewed by 457
Abstract
The transition of SiC MOSFET structure from planar to trench-based architectures requires the optimization of gate dielectric layers to improve device performance. This study utilizes a range of characterization techniques to explore the interfacial properties of ZrO2 and SiO2/ZrO2 [...] Read more.
The transition of SiC MOSFET structure from planar to trench-based architectures requires the optimization of gate dielectric layers to improve device performance. This study utilizes a range of characterization techniques to explore the interfacial properties of ZrO2 and SiO2/ZrO2 gate dielectric films, grown via atomic layer deposition (ALD) in SiC epitaxial trench structures to assess their performance and suitability for device applications. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements showed the deposition of smooth film morphologies with roughness below 1 nm for both ZrO2 and SiO2/ZrO2 gate dielectrics, while SE measurements revealed comparable physical thicknesses of 40.73 nm for ZrO2 and 41.55 nm for SiO2/ZrO2. X-ray photoelectron spectroscopy (XPS) shows that in SiO2/ZrO2 thin films, the binding energies of Zr 3d5/2 and Zr 3d3/2 peaks shift upward compared to pure ZrO2. Electrical characterization showed an enhancement of EBR (3.76 to 5.78 MV·cm−1) and a decrease of ION_EBR (1.94 to 2.09 × 10−3 A·cm−2) for the SiO2/ZrO2 stacks. Conduction mechanism analysis identified suppressed Schottky emission in the stacked film. This indicates that the incorporation of a thin SiO2 layer effectively mitigates the small bandgap offset, enhances the breakdown electric field, reduces leakage current, and improves device performance. Full article
(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))
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14 pages, 8353 KiB  
Article
Design and Characterization of an Equibiaxial Multi-Electrode Dielectric Elastomer Actuator
by Simon Holzer, Bhawnath Tiwari, Stefania Konstantinidi, Yoan Civet and Yves Perriard
Materials 2025, 18(8), 1693; https://doi.org/10.3390/ma18081693 - 8 Apr 2025
Viewed by 333
Abstract
With the ongoing journey of automation advancements and a trend towards miniaturization, the choice of actuator plays a crucial role. Over recent years, soft actuators have demonstrated their usefulness in various applications, especially where light weight and high strain are required. Dielectric elastomer [...] Read more.
With the ongoing journey of automation advancements and a trend towards miniaturization, the choice of actuator plays a crucial role. Over recent years, soft actuators have demonstrated their usefulness in various applications, especially where light weight and high strain are required. Dielectric elastomer actuators (DEAs) are a class of soft actuators that provide high-strain actuation possibilities in applications like biomedicine, logistics, or consumer electronics. A variety of work featuring DEAs for actuation has been carried out in recent years, but a single work detailing the design conception, fabrication, modeling and experimental validation is lacking, especially in the context of achieving high strains with the integration of multiple electrodes and their interaction. This work discusses these issues with an equibiaxial DEA, enabling optimized equibiaxial strain patterns due to full use of the available actuation area. The developed DEA can achieve an equibiaxial strain of 12.75% for actuation at 60 V μm−1 over an active area of 7 cm2 which is an improvement of 1.3 times compared to traditional dot actuators. These properties position the device as a promising alternative for various applications like cell cultures or microassembly and provide an advantage of optimized use of passive regions within the actuator. Full article
(This article belongs to the Special Issue Electroactive Polymers: Fundamentals and Applications)
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19 pages, 5369 KiB  
Article
Interactions of Terahertz Photons with Phonons of Two-Dimensional van der Waals MoS2/WSe2/MoS2 Heterostructures and Thermal Responses
by Jingwen Huang, Ningsheng Xu, Yumao Wu, Xue Ran, Yue Fang, Hongjia Zhu, Weiliang Wang, Huanjun Chen and Shaozhi Deng
Materials 2025, 18(7), 1665; https://doi.org/10.3390/ma18071665 - 4 Apr 2025
Viewed by 596
Abstract
The interaction between terahertz (THz) photons and phonons of materials is crucial for the development of THz photonics. In this work, typical two-dimensional (2D) van der Waals (vdW) transition metal chalcogenide (TMD) layers and heterostructures are used in THz time-domain spectroscopy (TDS) measurements, [...] Read more.
The interaction between terahertz (THz) photons and phonons of materials is crucial for the development of THz photonics. In this work, typical two-dimensional (2D) van der Waals (vdW) transition metal chalcogenide (TMD) layers and heterostructures are used in THz time-domain spectroscopy (TDS) measurements, low-wavenumber Raman spectroscopy measurements, calculation of 2D materials’ phonon spectra, and theoretical analysis of thermal responses. The TDS results reveal strong absorption of THz photons in the frequency range of 2.5–10 THz. The low-wavenumber Raman spectra show the phonon vibration characteristics and are used to establish phonon energy bands. We also set up a computational simulation model for thermal responses. The temperature increases and distributions in the individual layers and their heterostructures are calculated, showing that THz photon absorption results in significant increases in temperature and differences in the heterostructures. These give rise to interesting photothermal effects, including the Seebeck effect, resulting in voltages across the heterostructures. These findings provide valuable guidance for the potential optoelectronic application of the 2D vdW heterostructures. Full article
(This article belongs to the Special Issue Terahertz Vibrational Spectroscopy in Advanced Materials)
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17 pages, 3636 KiB  
Article
DFT Investigation of a Direct Z-Scheme Photocatalyst for Overall Water Splitting: Janus Ga2SSe/Bi2O3 Van Der Waals Heterojunction
by Fan Yang, Pascal Boulet and Marie-Christine Record
Materials 2025, 18(7), 1648; https://doi.org/10.3390/ma18071648 - 3 Apr 2025
Viewed by 479
Abstract
Constructing van der Waals heterojunctions with excellent properties has attracted considerable attention in the field of photocatalytic water splitting. In this study, four patterns, coined A, B, C, and D of Janus Ga2SSe/Bi2O3 van der Waals (vdW) heterojunctions [...] Read more.
Constructing van der Waals heterojunctions with excellent properties has attracted considerable attention in the field of photocatalytic water splitting. In this study, four patterns, coined A, B, C, and D of Janus Ga2SSe/Bi2O3 van der Waals (vdW) heterojunctions with different stacking modes, were investigated using first-principles calculations. Their stability, electronic structure, and optical properties were analyzed in detail. Among these, patterns A and C heterojunctions demonstrate stable behavior and operate as direct Z-scheme photocatalysts, exhibiting band gaps of 1.83 eV and 1.62 eV. In addition, the suitable band edge positions make them effective for photocatalytic water decomposition. The built-in electric field across the heterojunction interface effectively inhibits electron-hole recombination, thereby improving the photocatalytic efficiency. The optical absorption coefficients show that patterns A and C heterojunctions exhibit higher light absorption intensity than Ga2SSe and Bi2O3 monolayers, spanning from the ultraviolet to visible range. Their corrected solar-to-hydrogen (STH) efficiencies are 13.60% and 12.08%, respectively. The application of hydrostatic pressure and biaxial tensile strain demonstrate distinct effects on photocatalytic performance: hydrostatic pressure preferentially enhances the hydrogen evolution reaction (HER), while biaxial tensile strain primarily improves the oxygen evolution reaction (OER). Furthermore, the heterojunctions exhibited enhanced optical absorption across the UV-visible spectrum with increasing hydrostatic pressure. Notably, a 1% tensile strain results in an improvement in visible light absorption efficiency. These results demonstrate that Ga2SSe/Bi2O3 heterojunctions hold great promise as direct Z-scheme photocatalysts for overall water splitting. Full article
(This article belongs to the Special Issue Hierarchically Structured Materials for Photocatalysis, Electrocatalysis and Photoelectrocatalysis)
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15 pages, 6248 KiB  
Article
Precursor-Derived Mo2C/SiC Composites with a Two-Dimensional Sheet Structure for Electromagnetic Wave Absorption
by Yang Li, Wen Yang, Jipeng Zhang, Yongzhao Hou, Guangwu Wen, Guodong Xin, Meixian Jiang and Yongqiang Ma
Materials 2025, 18(7), 1573; https://doi.org/10.3390/ma18071573 - 31 Mar 2025
Viewed by 316
Abstract
Precursor-derived silicon carbide (SiC) ceramics have been widely used as absorbing materials, but the residual carbon sink produced by ceramicization limits their application under high-temperature and oxygen-containing conditions, such as the nozzle or jet vane of high-speed aircraft. In this paper, a novel [...] Read more.
Precursor-derived silicon carbide (SiC) ceramics have been widely used as absorbing materials, but the residual carbon sink produced by ceramicization limits their application under high-temperature and oxygen-containing conditions, such as the nozzle or jet vane of high-speed aircraft. In this paper, a novel molybdenum carbide/silicon carbide (Mo2C/SiC) microwave-absorbing ceramic with a two-dimensional sheet structure was obtained through the pyrolysis of polycarbosilane-coated molybdenum sulfide (PCS@MoS2). The results indicate that addition of an appropriate amount of MoS2 can react with the free carbon generated during the pyrolysis of PCS, thereby reducing the material’s carbon content and forming Mo2C. Concurrently, the layered structural characteristics of MoS2 are utilized to create a two-dimensional composite structure within the material, which enhances the material’s absorption vastly. The as-prepared Mo2C/SiC ceramics sintered at 1300 °C exhibit a minimum reflection loss (RLmin) of −46.49 dB at 8.96 GHz with a thickness of 2.6 mm. Additionally, the effective absorption bandwidth (EAB) of Mo2C/SiC spans the entire X-band (8–12 GHz) due to the combined effect of multiple loss mechanisms. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
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10 pages, 3175 KiB  
Article
Electric Field-Defined Superlattices in Bilayer Graphene: Formation of Topological Bands in Two Dimensions
by Włodzimierz Jaskólski
Materials 2025, 18(7), 1521; https://doi.org/10.3390/ma18071521 - 28 Mar 2025
Viewed by 418
Abstract
An electric field applied to the Bernal-stacked bilayer graphene opens an energy gap; its reversal in some regions creates domain walls and leads to the appearance of one-dimensional chiral gapless states localized at the walls. Here, we investigate the energy structure of bilayer [...] Read more.
An electric field applied to the Bernal-stacked bilayer graphene opens an energy gap; its reversal in some regions creates domain walls and leads to the appearance of one-dimensional chiral gapless states localized at the walls. Here, we investigate the energy structure of bilayer graphene with superlattice potential defined by an external electric field. The calculations are performed within an atomistic π-electron tight-binding approximation. We study one-dimensional and two-dimensional superlattices formed by arrays of electric-field walls in the zigzag and armchair directions and investigate different field polarizations. Chiral gapless states discretize due to the superlattice potential and transform into minibands in the energy gap. As the main result, we show that the minibands can cross at the Fermi level for some field polarizations. This leads to a new kind of two-dimensional gapless states of topological character that form Dirac-like cones at the crossing points. This also has application potential: changing the field polarization can close the energy gap and change the character of the superlattice from semiconducting to metallic. Full article
(This article belongs to the Special Issue Quantum Transport in Novel 2D Materials and Structures)
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17 pages, 7854 KiB  
Article
Understanding Polysiloxane Polymer to Amorphous SiOC Conversion During Pyrolysis Through ReaxFF Simulation
by Kathy Lu and Harrison Chaney
Materials 2025, 18(7), 1412; https://doi.org/10.3390/ma18071412 - 22 Mar 2025
Viewed by 351
Abstract
A significant challenge during the polymer-to-ceramic pyrolysis conversion is to understand the polymer-to-ceramic atomic evolution and correlate the composition changes with the precursor molecular structures, pyrolysis conditions, and resulting ceramic characteristics. In this study, a Reactive Force Field (ReaxFF) simulation approach has been [...] Read more.
A significant challenge during the polymer-to-ceramic pyrolysis conversion is to understand the polymer-to-ceramic atomic evolution and correlate the composition changes with the precursor molecular structures, pyrolysis conditions, and resulting ceramic characteristics. In this study, a Reactive Force Field (ReaxFF) simulation approach has been used to simulate silicon oxycarbide (SiOC) ceramic formation from four different polysiloxane precursors. For the first time, we show atomically that pyrolysis time and temperature proportionally impact the new Si-O rich and C rich cluster sizes as well as the composition separation of Si-O from C. Polymer side groups have a more complex effect on the Si-O and C cluster separation and growth, with ethyl group leading to the most Si-O cluster separation and phenyl group leading to the most C cluster separation. We also demonstrate never-before correlations of gas release with polymer molecular structures and functional groups. CH4, C2H6, C2H4, and H2 are preferentially released from the pyrolyzing systems. The sequence is determined by the polymer molecular structures. This work is the first to atomically illustrate the innate correlations between the polymer precursors and pyrolyzed ceramics. Full article
(This article belongs to the Special Issue Structural, Thermal, Electrical, and Electrochemical Properties of Novel Ceramics)
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18 pages, 74287 KiB  
Article
Graining and Texturing of Metal Surfaces by Picosecond Laser Treatment
by Carmelo Corsaro, Fortunato Neri, Paolo Maria Ossi, Domenico Bonanno, Priscilla Pelleriti and Enza Fazio
Materials 2025, 18(7), 1398; https://doi.org/10.3390/ma18071398 - 21 Mar 2025
Viewed by 509
Abstract
Different approaches have been proposed to control the tribological behavior of materials under different conformal and non-conformal contact conditions with influenced surface texturing. The ever-increasing demand to improve material friction, erosion wear, and adhesion bond strength of coatings is a major concern for [...] Read more.
Different approaches have been proposed to control the tribological behavior of materials under different conformal and non-conformal contact conditions with influenced surface texturing. The ever-increasing demand to improve material friction, erosion wear, and adhesion bond strength of coatings is a major concern for the contact interface of surfaces. Laser texturing is considered a promising approach to tuning materials’ tribological properties. The latter are strongly influenced by the texture density and shape imprinted on the engineered materials and vary in dry or lubricating conditions. In this work, the physicochemical properties of picosecond laser-textured surfaces of metallic materials have been systematically analyzed. Specifically, the wettability character of laser-textured materials was correlated with their morphological/compositional features. Full article
(This article belongs to the Section Materials Physics)
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17 pages, 3101 KiB  
Article
Removal of Per- and Polyfluoroalkyl Substances Using Commercially Available Sorbents
by Zhiming Zhang, Sevda Joudiazar, Anshuman Satpathy, Eustace Fernando, Roxana Rahmati, Junchul Kim, Giacomo de Falco, Rupali Datta and Dibyendu Sarkar
Materials 2025, 18(6), 1299; https://doi.org/10.3390/ma18061299 - 15 Mar 2025
Viewed by 1655
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants of growing environmental and human health concern, widely detected across various environmental compartments. Effective remediation strategies are essential to mitigate their widespread impacts. This study compared the performance of two types of commercially available [...] Read more.
Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants of growing environmental and human health concern, widely detected across various environmental compartments. Effective remediation strategies are essential to mitigate their widespread impacts. This study compared the performance of two types of commercially available sorbent materials, granular activated carbon (GAC, Filtrasorb-400) and organoclays (OC-200, and modified organoclays Fluoro-sorb-100 and Fluoro-sorb-200) for the removal of three representative PFAS compounds: perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonic acid (PFOS) from water. Both organoclays and modified organoclays outperformed GAC, likely due to electrostatic interactions between the anionic PFAS compounds and the cationic functional groups of the modified organoclays. A pseudo-second-order kinetic model best described the rapid sorption kinetics of PFOA, PFNA, and PFOS. For PFOA, OC-200 demonstrated the highest adsorption capacities (qmax = 47.17 µg/g). For PFNA and PFOS, Fluoro-sorb-100 was the most effective sorbent, with qmax values at 99.01 µg/g and 65.79 µg/g, respectively. Desorption studies indicated that the sorption of the three PFAS compounds on these commercially available sorbents was largely irreversible. This study highlights the effectiveness and sorption capacities of different types of commercial sorbents for PFAS removal and offers valuable insights into the selection of reactive media for PFAS removal from water under environmentally relevant conditions. Full article
(This article belongs to the Special Issue Advanced Nanoporous and Mesoporous Materials)
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13 pages, 1891 KiB  
Article
Microstructure-Based Magneto-Mechanical Modeling of Magnetorheological Elastomer Composites: A Comparable Analysis of Dipole and Maxwell Methods
by Shengwei Feng and Lizhi Sun
Materials 2025, 18(5), 1187; https://doi.org/10.3390/ma18051187 - 6 Mar 2025
Viewed by 643
Abstract
Magnetorheological elastomers (MREs) are smart composite materials with tunable mechanical properties by ferromagnetic particle interactions. This study applied the microstructure-based dipole and Maxwell methods to evaluate the magneto-mechanical coupling and magnetostrictive responses of MREs, focusing on various particle distributions. The finite element modeling [...] Read more.
Magnetorheological elastomers (MREs) are smart composite materials with tunable mechanical properties by ferromagnetic particle interactions. This study applied the microstructure-based dipole and Maxwell methods to evaluate the magneto-mechanical coupling and magnetostrictive responses of MREs, focusing on various particle distributions. The finite element modeling of representative volume elements with fixed volume fractions revealed that the straight chain microstructure exhibits the most significant magnetostrictive effect due to its low initial shear stiffness and significant magnetic force contributions. For particle separations exceeding three radii, the dipole and Maxwell methods yield consistent results for vertically or horizontally aligned particles. For particle separations greater than three radii, the dipole and Maxwell methods produce consistent results for vertically and horizontally aligned particles. However, discrepancies emerge for angled configurations and complex microstructures, with the largest deviation observed in the hexagonal particle distribution, where the two methods differ by approximately 27%. These findings highlight the importance of selecting appropriate modeling methods for optimizing MRE performance. Since anisotropic MREs with straight-chain alignments are the most widely used, our results confirm that the dipole method offers an efficient alternative to the Maxwell method for simulating these structures. Full article
(This article belongs to the Special Issue Smart Soft Materials: From Design to Applications)
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18 pages, 7417 KiB  
Article
An Efficient Optimization Method for Large-Solution Space Electromagnetic Automatic Design
by Lingyan He, Fengling Peng and Xing Chen
Materials 2025, 18(5), 1159; https://doi.org/10.3390/ma18051159 - 5 Mar 2025
Viewed by 602
Abstract
In the field of electromagnetic design, it is sometimes necessary to search for the optimal design solution (i.e., the optimal solution) within a large solution space to complete the optimization. However, traditional optimization methods are not only slow in searching for the solution [...] Read more.
In the field of electromagnetic design, it is sometimes necessary to search for the optimal design solution (i.e., the optimal solution) within a large solution space to complete the optimization. However, traditional optimization methods are not only slow in searching for the solution space but are also prone to becoming trapped in local optima, leading to optimization failure. This paper proposes a dual-population genetic algorithm to quickly find the optimal solution for electromagnetic optimization problems in large solution spaces. The method involves two populations: the first population uses the powerful dynamic decision-making ability of reinforcement learning to adjust the crossover probability, making the optimization process more stable and enhancing the global optimization capability of the algorithm. The second population accelerates the convergence speed of the algorithm by employing a “leader dominance” mechanism, allowing the population to quickly approach the optimal solution. The two populations are integrated through an immigration operator, improving optimization efficiency. The effectiveness of the proposed method is demonstrated through the optimization design of an electromagnetic metasurface material. Furthermore, the method designed in this paper is not limited to the electromagnetic field and has practical value in other engineering optimization areas, such as vehicle routing optimization, energy system optimization, and fluid dynamics optimization, etc. Full article
(This article belongs to the Special Issue Metamaterials and Metasurfaces: From Materials to Applications)
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16 pages, 6479 KiB  
Article
Vat Photopolymerization of CeO2-Incorporated Hydrogel Scaffolds with Antimicrobial Efficacy
by Nelly Aimelyne Mpuhwe, Gyu-Nam Kim and Young-Hag Koh
Materials 2025, 18(5), 1125; https://doi.org/10.3390/ma18051125 - 2 Mar 2025
Viewed by 891
Abstract
We herein demonstrate the utility of gelatin methacryloyl (GelMA)/poly(ethylene glycol) diacrylate (PEGDA)–cerium oxide (CeO2) hydrogel inks for manufacturing hydrogel scaffolds with antimicrobial efficacy by vat photopolymerization. For uniform blending with GelMA/PEGDA hydrogels, CeO2 nanoparticles with a round shape were synthesized [...] Read more.
We herein demonstrate the utility of gelatin methacryloyl (GelMA)/poly(ethylene glycol) diacrylate (PEGDA)–cerium oxide (CeO2) hydrogel inks for manufacturing hydrogel scaffolds with antimicrobial efficacy by vat photopolymerization. For uniform blending with GelMA/PEGDA hydrogels, CeO2 nanoparticles with a round shape were synthesized by the precipitation method coupled with calculation at 600 °C. In addition, they had highly crystalline phases and the desired chemical structures (oxidation states of Ce3+ and Ce4+) required for outstanding antimicrobial efficacy. A range of GelMA/PEGDA-CeO2 hydrogel scaffolds with different CeO2 contents (0% w/v, 0.1% w/v, 0.5% w/v, 1% w/v, and 5% w/v with respect to distilled water content) were manufactured. The photopolymerization behavior, mechanical properties, and biological properties (swelling and biodegradation behaviors) of hydrogel scaffolds were characterized to optimize the CeO2 content. GelMA/PEGDA-CeO2 hydrogel scaffolds produced with the highest CeO2 content (5% w/v) showed reasonable mechanical properties (compressive strength = 0.56 ± 0.09 MPa and compressive modulus = 0.19 ± 0.03 MPa), a high swelling ratio (1063.3 ± 10.9%), and the desired biodegradation rate (remaining weight after 28 days = 39.6 ± 2.3%). Furthermore, they showed outstanding antimicrobial efficacy (the number of colony-forming units = 76 ± 44.6 (×103)). In addition, macroporous GelMA/PEGDA-CeO2 hydrogel scaffolds with tightly controlled porous structures could be manufactured by vat photopolymerization. Full article
(This article belongs to the Section Biomaterials)
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19 pages, 10708 KiB  
Article
Evaluation of the Influence of Primary and Secondary Crystal Orientations and Selected Structural Characteristics on Creep Resistance in Single-Crystal Nickel-Based Turbine Blades
by Kamil Gancarczyk, Robert Albrecht, Paweł Sułkowicz, Mirosław Szala and Mariusz Walczak
Materials 2025, 18(5), 919; https://doi.org/10.3390/ma18050919 - 20 Feb 2025
Cited by 2 | Viewed by 529
Abstract
This study evaluates the perfection of the crystal structure of single-crystal turbine blade castings made from the CMSX-4 nickel superalloy. The analysis included primary and secondary crystal orientation measurements using the Ω-scan method and the novel OD-EFG X-ray diffractometer. The selected microstructural parameters [...] Read more.
This study evaluates the perfection of the crystal structure of single-crystal turbine blade castings made from the CMSX-4 nickel superalloy. The analysis included primary and secondary crystal orientation measurements using the Ω-scan method and the novel OD-EFG X-ray diffractometer. The selected microstructural parameters of the single crystals were also analyzed, including the assessment of stereological parameters and the degree of porosity. A creep test was performed according to standard procedures and under conditions simulating real operational environments. The model single-crystal turbine blades were manufactured using the Bridgman–Stockbarger method, with variable withdrawal rates of 1 and 3 mm/min. Heat treatment of the single-crystal castings involved solution treatment followed by double aging. The evaluation of structural perfection was carried out in three states: as-cast, after solution heat treatment, and after double aging. The crystallographic orientation of the blades was determined on both the airfoil and the root part. The study determined how crystallographic orientation and microstructural parameters influence the creep resistance of the castings. It was found that in the as-cast condition, the greatest influence on high creep strength has a small deviation of the primary and constant value of secondary crystal orientation along the height of the blade casting. After heat treatment, the highest creep resistance was obtained for the blade manufactured at a withdrawal rate at 1 mm/min. Full article
(This article belongs to the Section Metals and Alloys)
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51 pages, 17258 KiB  
Review
A Review of Simulation Tools Utilization for the Process of Laser Powder Bed Fusion
by Ľuboš Kaščák, Ján Varga, Jana Bidulská, Róbert Bidulský and Tibor Kvačkaj
Materials 2025, 18(4), 895; https://doi.org/10.3390/ma18040895 - 18 Feb 2025
Cited by 1 | Viewed by 915
Abstract
This review describes the process of metal additive manufacturing and focuses on the possibility of correlated input parameters that are important for this process. The correlation of individual parameters in the metal additive manufacturing process is considered using simulation tools that allow the [...] Read more.
This review describes the process of metal additive manufacturing and focuses on the possibility of correlated input parameters that are important for this process. The correlation of individual parameters in the metal additive manufacturing process is considered using simulation tools that allow the prediction of various defects, thus making the real production process more efficient, especially in terms of time and costs. Special attention is paid to multiple applications using these simulation tools as an initial analysis to determine the material’s behavior when defining various input factors, including the results obtained. Based on this, further procedures were implemented, including real production parts. This review also points out the range of possible variations that simulation tools have, which helps to effectively predict material defects and determine the volume of consumed material, supports construction risk, and other information necessary to obtain a quality part in the production process. From the overview of the application of simulation tools in this process, it was found that the correlation between theoretical knowledge and the definition of individual process parameters and other variables are related and are of fundamental importance for achieving the final part with the required properties. In terms of some specific findings, it can be noted that simulation tools identify adverse phenomena occurring in the production processes and allow manufacturers to test the validity of the proposed conceptual and model solutions without making actual changes in the production system, and they have the measurable impact on the design and production of quality parts. Full article
(This article belongs to the Special Issue Plastic Deformation and Mechanical Behavior of Metallic Materials)
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13 pages, 3773 KiB  
Article
Transition-Metal-Doped Nickel–Cobalt Layered Double Hydroxide Catalysts for an Efficient Oxygen Evolution Reaction
by Zhihan Li, Wenjing Yi, Qingqing Pang, Meng Zhang and Zhongyi Liu
Materials 2025, 18(4), 877; https://doi.org/10.3390/ma18040877 - 17 Feb 2025
Viewed by 1121
Abstract
Hydrogen plays a vital role in the global shift toward cleaner energy solutions, with water electrolysis standing out as one of the most promising techniques for generating hydrogen. Despite its potential, the oxygen evolution reaction (OER) involved in this process faces significant challenges, [...] Read more.
Hydrogen plays a vital role in the global shift toward cleaner energy solutions, with water electrolysis standing out as one of the most promising techniques for generating hydrogen. Despite its potential, the oxygen evolution reaction (OER) involved in this process faces significant challenges, including high overpotentials and slow reaction rates, which underscore the need for advanced electrocatalytic materials to enhance efficiency. Noble metal catalysts are effective but expensive, so transition-metal-based electrocatalysts like nickel–cobalt layered double hydroxides (NiCo LDHs) have become promising alternatives. In this research, a series of NiCo LDH catalysts doped with Fe, Mn, Cu, and Zn were effectively produced using a one-step hydrothermal technique. Among the catalysts, the Fe-doped NiCo LDH exhibited OER activity, achieving a lower overpotential (289 mV) at a current density of 50 mA/cm2, which was far better than the 450 mV of the undoped NiCo LDH. The Mn-, Cu-, and Zn-NiCo LDHs also exhibited lower overpotentials of 414 mV, 403 mV, and 357 mV, respectively, at this current density. The Fe-doped NiCo LDH had a 3D layered nanoflower structure, increasing the surface area for reactant adsorption. The electrochemically active surface area (ECSA), as indicated by the double-layer capacitance (Cdl), was larger in the doped samples. The Cdl value of the Fe-doped NiCo LDH was 3.72 mF/cm2, significantly surpassing the 0.82 mF/cm2 of the undoped NiCo LDH. These changes improved charge transfer and optimized reaction kinetics, enhancing the overall OER performance. This study offers significant contributions to the development of efficient electrocatalysts for the OER, advancing the understanding of key design principles for enhanced catalytic performance. Full article
(This article belongs to the Special Issue Research on Electrocatalytic Materials for Hydrogen Evolution and Oxygen Evolution)
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11 pages, 1999 KiB  
Article
Giant Seebeck Effect in a PEDOT Material Coated on a Felt Fiber
by Hideki Arimatsu, Yuki Osada, Ryo Takagi and Takuya Fujima
Materials 2025, 18(4), 838; https://doi.org/10.3390/ma18040838 - 14 Feb 2025
Viewed by 535
Abstract
Poly(3,4-ethylenedioxythiophene) (PEDOT) has been extensively investigated not only as a conductive polymer but also as a promising thermoelectric material. Numerous efforts have been undertaken to enhance the thermoelectric performance, particularly because improving the Seebeck coefficient is crucial for practical applications. In this study, [...] Read more.
Poly(3,4-ethylenedioxythiophene) (PEDOT) has been extensively investigated not only as a conductive polymer but also as a promising thermoelectric material. Numerous efforts have been undertaken to enhance the thermoelectric performance, particularly because improving the Seebeck coefficient is crucial for practical applications. In this study, we explored the thermoelectric property modification of PEDOT using a low-molecular carrier dopant and a fibrous substrate. PEDOT was coated on a felt texture with p-toluenesulfonic acid (PTSA) as the carrier dopant. The thermoelectric properties, including the Seebeck coefficient and electric conductivity, were measured. Raman spectroscopy was used to characterize the molecular strain of the PEDOT. The PEDOT sample coated on a felt texture with PTSA exhibited a wide range of Seebeck coefficients (−2100 to 3100 μV K−1). An estimation suggested the power factor reached 2400 µW m−1 K−2 for the p-type and 1100 µW m−1 K−2 for the n-type at the maxima. Raman spectroscopy showed a strong correlation between the strain in the Cβ-Cβ bond of the PEDOT molecule and its Seebeck coefficient. Full article
(This article belongs to the Special Issue Advanced Thin Film Materials for Energy Conversion and Storage Applications)
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15 pages, 8628 KiB  
Article
Improving Biodegradable Mg-Zn(-Ca) Alloys by Surface Treatment via Plasma Electrolytic Oxidation
by Jakub Vertaľ, Daniel Kajánek, Jiří Kubásek and Peter Minárik
Materials 2025, 18(4), 747; https://doi.org/10.3390/ma18040747 - 8 Feb 2025
Cited by 2 | Viewed by 628
Abstract
This study investigated the influence of plasma electrolytic oxidation (PEO) preparation time on the degradation resistance of Mg-1Zn (Z1) and Mg-1Zn-0.4Ca (ZX10) alloys, with comparisons to pure Mg and commercial Mg-4Y-3RE-0.4Zr (WE43). PEO layers were formed with varying preparation times (5, 10, and [...] Read more.
This study investigated the influence of plasma electrolytic oxidation (PEO) preparation time on the degradation resistance of Mg-1Zn (Z1) and Mg-1Zn-0.4Ca (ZX10) alloys, with comparisons to pure Mg and commercial Mg-4Y-3RE-0.4Zr (WE43). PEO layers were formed with varying preparation times (5, 10, and 15 min) and analyzed for microstructure, morphology, and corrosion resistance. The results indicated that PEO layers with a 10 min preparation time had the most homogeneous structure and optimal corrosion resistance. Prolonged PEO preparation times increased pore density, crack formation, and layer thickness while also promoting layer degradation during extended immersion in 0.9% NaCl corrosive media. The dissolution of phosphates from PEO layers contributes to the formation of a protective corrosion layer, enhancing long-term resistance. These findings demonstrate that low-alloyed, biocompatible Mg-Zn(-Ca) alloys can achieve corrosion resistance comparable to high-performance WE43 alloys through appropriate surface treatment. Full article
(This article belongs to the Special Issue Corrosion Behavior and Mechanical Properties of Metallic Materials)
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14 pages, 4269 KiB  
Article
Insights into HKUST-1 Metal-Organic Framework’s Morphology and Physicochemical Properties Induced by Changing the Copper(II) Salt Precursors
by Joanna Klęba, Kun Zheng, Dorota Duraczyńska, Mateusz Marzec, Monika Fedyna and Jakub Mokrzycki
Materials 2025, 18(3), 676; https://doi.org/10.3390/ma18030676 - 3 Feb 2025
Viewed by 1777
Abstract
The HKUST-1 metal-organic framework was synthesized using four different copper(II) salt precursors, namely copper nitrate, copper sulphate, copper acetate, and copper chloride, via the solvothermal method with no mixing. Syntheses were conducted without using the N,N-dimethylformamide to allow for a greener synthesis of [...] Read more.
The HKUST-1 metal-organic framework was synthesized using four different copper(II) salt precursors, namely copper nitrate, copper sulphate, copper acetate, and copper chloride, via the solvothermal method with no mixing. Syntheses were conducted without using the N,N-dimethylformamide to allow for a greener synthesis of MOFs. The selected physicochemical properties of the obtained metal-organic frameworks were determined. The yield of the obtained products changed in the order acetate>nitrate>sulfate, while no product was obtained in the synthesis with copper(II) chloride. The obtained materials were characterized by means of XRD, nitrogen adsorption–desorption at −196 °C, FTIR, XPS, TGA, SEM, and DLS. The morphology of crystallites and their physicochemical properties were significantly affected when different copper(II) salt precursors were used. The comparison of the obtained results with already published works allows for the correlation of the synthesis parameters like synthesis temperature, time, mixing, and copper(II) salt precursor used on selected properties of the final product. Full article
(This article belongs to the Special Issue Advanced Nanoporous and Mesoporous Materials)
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15 pages, 8890 KiB  
Article
Application of Magnetic-Assisted Polishing Using Metal-Bonded Grinding Wheels for Machining Silicon Nitride Ball Bearings
by Su-Yeon Han, Seung-Min Lee, Ha-Neul Kim, Jae-Woong Ko and Tae-Soo Kwak
Materials 2025, 18(3), 677; https://doi.org/10.3390/ma18030677 - 3 Feb 2025
Viewed by 806
Abstract
Silicon nitride (Si3N4) is used for high-speed rotating bearings in machine tools, aircraft, and turbo pumps due to its excellent material properties such as high-temperature strength, hardness, and fracture toughness. Grinding with fixed abrasives enables high shape accuracy and [...] Read more.
Silicon nitride (Si3N4) is used for high-speed rotating bearings in machine tools, aircraft, and turbo pumps due to its excellent material properties such as high-temperature strength, hardness, and fracture toughness. Grinding with fixed abrasives enables high shape accuracy and high efficiency in machining brittle materials. However, it is difficult to completely remove surface damage, which limits its use in products requiring a nano surface. These defects also result in reduced reliability and shortened lifespan. Magnetic-assisted polishing (MAP) is a technology that can achieve a fine surface by using a mixture of iron powder and abrasives, but it requires a lot of time due to the low material removal rate (MRR). Therefore, this study developed a hybrid processing technology using a metal-bonded grinding wheel and a slurry with hard abrasives for the high precision of silicon nitride ceramic ball bearings. Experiments were conducted in order to compare and analyze the surface roughness and material removal rate. Through MAP, using a grinding wheel with low grit (#325), high-efficiency machining performance was confirmed with a maximum material removal rate of 1.193 mg/min. In MAP, using a grinding wheel with high grit (#2000), a nano-level surface roughness of 6.5 nm Ra was achieved. Full article
(This article belongs to the Special Issue Functionalized Ceramics and Their Composites: Preparation, Properties and Applications)
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17 pages, 1743 KiB  
Article
Fabrication and Characterization of Electrospun DegraPol® Tubes Releasing TIMP-1 Protein to Modulate Tendon Healing
by Julia Rieber, Roger Khalid Niederhauser, Pietro Giovanoli and Johanna Buschmann
Materials 2025, 18(3), 665; https://doi.org/10.3390/ma18030665 - 3 Feb 2025
Cited by 3 | Viewed by 925
Abstract
Background: Tendon rupture repair can result from fibrotic scar formation through imbalanced ECM deposition during remodeling. The tissue inhibitors of matrix metalloprotease (TIMPs) not only decrease ECM degradation, regulated by matrix metalloproteases (MMPs), but also restrict TGF-β1 activation and thus diminish fibrosis. Methods: [...] Read more.
Background: Tendon rupture repair can result from fibrotic scar formation through imbalanced ECM deposition during remodeling. The tissue inhibitors of matrix metalloprotease (TIMPs) not only decrease ECM degradation, regulated by matrix metalloproteases (MMPs), but also restrict TGF-β1 activation and thus diminish fibrosis. Methods: Rabbit tenocytes (rbTenocytes) and rabbit adipose-derived stem cells (rbASCs) were cultivated under different TIMP-1 concentrations. Proliferation and gene expression were assessed. TIMP-1 was incorporated into emulsion electrospun DegraPol® (DP) tubes that were characterized by SEM for fiber thickness, pore size, and wall thickness. Static and dynamic water contact angles, FTIR spectra, and TIMP-1 release kinetics were determined. Results: While the proliferation of rbTenocytes and rbACS was not affected by TIMP-1 supplementation in vitro, the gene expression of Col1A1 was increased in rbTenocytes, the gene expression of ki67 was increased in both cell types, the gene expression of tenomodulin was increased in both cell types at 100 ng/mL TIMP-1, and alkaline phosphatase expression ALP rose significantly in rbASCs. Electrospun TIMP-1/DP fibers had a ~5 μm diameter, a ~10 μm pore size, and a mesh thickness of ~200 μm. TIMP-1/DP meshes were more hydrophilic than pure DP meshes. TIMP-1 was released from the meshes with a sustained release of up to 7 days. Conclusions: TIMP-1/DP tubes may be used to modulate the fibrotic tissue reaction when applied around conventionally sutured tendon ruptures. Full article
(This article belongs to the Special Issue Physico-Chemical Modification of Materials for Biomedical Application)
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19 pages, 9311 KiB  
Article
B-H Curve Estimation and Air Gap Optimization for High-Performance Split Core
by Minjoong Kim, Myungseo Lee, Sijeong Lee, Jaeyun Lee and Jihwan Song
Materials 2025, 18(3), 644; https://doi.org/10.3390/ma18030644 - 31 Jan 2025
Viewed by 990
Abstract
The current transformer (CT)-based energy harvesting method has gained considerable attention for low-power devices. Accurate estimation of the B-H curve is essential to develop a high-performance CT, as it closely relates to the electromagnetic behavior of CT material. However, the existing estimation methods [...] Read more.
The current transformer (CT)-based energy harvesting method has gained considerable attention for low-power devices. Accurate estimation of the B-H curve is essential to develop a high-performance CT, as it closely relates to the electromagnetic behavior of CT material. However, the existing estimation methods for the B-H curve face several drawbacks, which include process complexity and a high cost. This study presented an intuitive method to estimate the B-H curve based on the experimentally obtained resistance-voltage data. The performance of the CT core is obtained based on the estimated B-H curve, which exhibited an error of only 2.6% when compared to the experimental results for the most accurate case. Additionally, we analyzed split-core performance deterioration caused by the presence of an air gap. The air gap formation of the split core was closely related to the surface roughness, which significantly influenced core performance. The air gap range that minimizes the reduction in performance is predicted and validated through simulations and experiments. This research highlights a straightforward approach to obtaining the B-H curve of magnetic CT core material. We believe that this study provides the design guidelines needed to develop a high-performance CT core, including considerations for core geometry and the recommended air gap range. Full article
(This article belongs to the Special Issue Functional Soft Magnetic Materials and Electromagnetic Shielding Technology)
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19 pages, 12564 KiB  
Article
Compressive Properties of Composite Sandwich Structure with Fractal Tree-Inspired Lattice Core
by Jian Han, Xin Ma, Rui Yang and Shiyong Sun
Materials 2025, 18(3), 606; https://doi.org/10.3390/ma18030606 - 29 Jan 2025
Viewed by 978
Abstract
A novel sandwich structure of a fractal tree-like lattice (SSFL) is proposed. The geometry characteristics were constructed based on the fractal tree-like patterns found in many biological structures, such as giant water lilies and dragon blood trees. The compressive performance of the proposed [...] Read more.
A novel sandwich structure of a fractal tree-like lattice (SSFL) is proposed. The geometry characteristics were constructed based on the fractal tree-like patterns found in many biological structures, such as giant water lilies and dragon blood trees. The compressive performance of the proposed structures with different fractal orders was experimentally and numerically investigated. The experimental samples were made by 3D printing technology. Axial compression tests were conducted to study the compressive performance and failure mode of the SSFLs. The results indicated that the new structure was good at multiple bearing and energy absorption. The finite element method (FEM) was performed to investigate the influence of geometry parameters on the compression behaviors of the SSFLs. The findings of this study provide an effective guide for using the fractal method to design lattice structures with a high bearing capacity. Full article
(This article belongs to the Special Issue Advances in Porous Lightweight Materials and Lattice Structures)
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17 pages, 3137 KiB  
Article
Efficient Photoelectrochemical Reduction of CO2 in Seawater with Cheap and Abundant Cu2O/Al2O3/TiO2 Electrode
by Aleksandra Parzuch, Katarzyna Kuder, Kostiantyn Nikiforow, Piotr Wróbel, Grzegorz Kaproń, Krzysztof Bieńkowski and Renata Solarska
Materials 2025, 18(3), 620; https://doi.org/10.3390/ma18030620 - 29 Jan 2025
Viewed by 863
Abstract
The photoelectrochemical (PEC) reduction of carbon dioxide to environmentally friendly fuels is a promising strategy to address the challenge of clean energy demand. Semiconductor photocathodes such as Cu2O enable the reduction of carbon dioxide, but their main drawback is their instability [...] Read more.
The photoelectrochemical (PEC) reduction of carbon dioxide to environmentally friendly fuels is a promising strategy to address the challenge of clean energy demand. Semiconductor photocathodes such as Cu2O enable the reduction of carbon dioxide, but their main drawback is their instability and susceptibility to photocorrosion. In this work, Al2O3 and TiO2 were utilized to enhance stability, photoelectrochemical activity, and charge transport facilitation, resulting in a 2.8-fold increase in generated photocurrent density (1.4 mA/cm2 at −0.2 V vs. RHE). The experiments were conducted in a 0.5 M NaCl solution, simulating seawater conditions, to evaluate the performance and stability of the system in an environment closer to real-world applications Full article
(This article belongs to the Special Issue Advances in Multicomponent Catalytic Materials)
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19 pages, 4921 KiB  
Article
Stiffness Compensation in Variable Displacement Mechanisms of Swash Plate Axial Piston Pumps Utilizing Piezoelectric Actuators
by Guangcheng Zhang, Mengxiang Ma and Yueh-Jaw Lin
Materials 2025, 18(3), 520; https://doi.org/10.3390/ma18030520 - 23 Jan 2025
Viewed by 792
Abstract
Swash plate axial piston pumps play an important role in hydraulic systems due to their superior performance and compact design. As the controlled object of the valve-controlled hydraulic cylinder, the swash plate is affected by the complex fluid dynamics effect and the mechanical [...] Read more.
Swash plate axial piston pumps play an important role in hydraulic systems due to their superior performance and compact design. As the controlled object of the valve-controlled hydraulic cylinder, the swash plate is affected by the complex fluid dynamics effect and the mechanical structure, which is prone to vibration, during the working process, thereby adversely affecting the dynamic performance of the system. In this paper, an electronically controlled ball screw type variable displacement mechanism with stiffness compensation is proposed. By introducing piezoelectric ceramic materials into the nut assembly, dynamic stiffness compensation of the system is achieved, which effectively changes the vibration characteristics of the swash plate and thus significantly improves the working stability of the system. Based on this, the stiffness model of a double nut ball screw is established to obtain the relationship between piezoelectric ceramics and the double nut. An asymmetric Bouc–Wen piezoelectric actuator model with nonlinear hysteresis characteristics is also established, and a particle swarm algorithm with improved inertia weights is utilized to identify the parameters of the asymmetric Bouc–Wen model. Finally, a piezoelectric actuator model based on the feedforward inverse model and a PID composite control algorithm is applied to the variable displacement mechanism system for stiffness compensation. Full article
(This article belongs to the Special Issue Advances in Smart Materials and Applications)
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26 pages, 7707 KiB  
Review
Textured Lead-Free Piezoelectric Ceramics: A Review of Template Effects
by Temesgen Tadeyos Zate, Cenk Abdurrahmanoglu, Vincenzo Esposito and Astri Bjørnetun Haugen
Materials 2025, 18(3), 477; https://doi.org/10.3390/ma18030477 - 21 Jan 2025
Cited by 3 | Viewed by 1378
Abstract
Crystallographic texture engineering through templated grain growth (TGG) has gained prominence as a highly effective strategy for optimizing the electromechanical performance of lead-free piezoelectric ceramics, offering a pathway toward sustainable alternatives to lead-based systems like lead zirconate titanate (PZT). By achieving high degrees [...] Read more.
Crystallographic texture engineering through templated grain growth (TGG) has gained prominence as a highly effective strategy for optimizing the electromechanical performance of lead-free piezoelectric ceramics, offering a pathway toward sustainable alternatives to lead-based systems like lead zirconate titanate (PZT). By achieving high degrees of texture, with Lotgering factors (LFs) often exceeding 90%, these systems have demonstrated piezoelectric properties that rival or even surpass their lead-based counterparts. Despite these advancements, the field lacks a comprehensive understanding of how specific template parameters influence the texture quality and functional properties across different material systems. This review provides an in-depth analysis of the influence of the template morphology, composition, and crystallographic orientation on the texturing of key lead-free systems, including BaTiO3 (BT), (K0.5Na0.5)NbO3 (KNN), and Bi0.5Na0.5TiO3 (BNT). Furthermore, it explores how the template selection affects the induced crystallographic direction, and how this impacts the material’s phase structure and domain configurations, ultimately influencing the piezoelectric and dielectric properties. By consolidating the existing knowledge and identifying current challenges, this work highlights key strategies for optimizing the texture and electromechanical performance in lead-free ceramics, providing essential insights for future research aimed at advancing high-performance, environmentally friendly piezoelectric materials for applications such as sensors, actuators, and energy-harvesting devices. Full article
(This article belongs to the Special Issue Sustainable Dielectric, Piezoelectric and Ferroelectric Materials: Synthesis, Characterization and Modelling)
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23 pages, 24751 KiB  
Article
From Powders to Performance—A Comprehensive Study of Two Advanced Cutting Tool Materials Sintered with Pressure Assisted Methods
by Kinga Momot, Piotr Klimczyk, Beata Leszczyńska-Madej, Marcin Podsiadło, Yuliia Rumiantseva and Agnieszka Gubernat
Materials 2025, 18(2), 461; https://doi.org/10.3390/ma18020461 - 20 Jan 2025
Viewed by 972
Abstract
This paper presents a comprehensive study of two tool materials designed for the machining of Inconel 718 superalloy, produced through two distinct sintering techniques: High Pressure–High Temperature (HPHT) sintering and Spark Plasma Sintering (SPS). The first composite (marked as BNT), composed of 65 [...] Read more.
This paper presents a comprehensive study of two tool materials designed for the machining of Inconel 718 superalloy, produced through two distinct sintering techniques: High Pressure–High Temperature (HPHT) sintering and Spark Plasma Sintering (SPS). The first composite (marked as BNT), composed of 65 vol% cubic boron nitride (cBN), was sintered from the cBN–TiN–Ti3SiC2 system using the HPHT technique at a pressure of 7.7 GPa. The second composite (marked as AZW) was fabricated from the Al2O3–ZrO2–WC system using SPS at a pressure of 63 MPa. The final phase composition of BNT material differed significantly from the initial composition due to reactions occurred during sintering. In contrast, the phase composition of the AZW ceramic composite before and after sintering was similar. The materials exhibited high quality, as evidenced by a Young’s modulus of 580 GPa for BNT and 470 GPa for AZW, along with hardness of 26 GPa for BNT and 21 GPa for AZW. Both composites were used to prepare cutting inserts that were evaluated for their performance in machining Inconel 718 alloy. While both inserts showed durability comparable to their respective reference commercial inserts, they differed in performance and price relative to one another. Full article
(This article belongs to the Special Issue Advances in Multifunctional Materials Obtained at High Temperature and Pressure Conditions)
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17 pages, 3373 KiB  
Review
Materials with Negative Permittivity or Negative Permeability—Review, Electrodynamic Modelling, and Applications
by Jerzy Krupka
Materials 2025, 18(2), 423; https://doi.org/10.3390/ma18020423 - 17 Jan 2025
Cited by 1 | Viewed by 1431
Abstract
A review of natural materials that exhibit negative permittivity or permeability, including gaseous plasma, metals, superconductors, and ferromagnetic materials, is presented. It is shown that samples made of such materials can store large amount of the electric (magnetic) energy and create plasmonic resonators [...] Read more.
A review of natural materials that exhibit negative permittivity or permeability, including gaseous plasma, metals, superconductors, and ferromagnetic materials, is presented. It is shown that samples made of such materials can store large amount of the electric (magnetic) energy and create plasmonic resonators for certain values of permittivity, permeability, and dimensions. The electric and the magnetic plasmon resonances in spherical samples made of such materials are analyzed using rigorous electrodynamic methods, and the results of the analysis are compared to experimental data and to results obtained with other methods. The results of free oscillation and Mie scattering theories are compared. Similarities and differences between permittivity and permeability tensors for magnetized plasma and magnetized ferromagnetic materials are underlined. Several physical phenomena are explained on the grounds of rigorous electrodynamic analysis and experiments. These phenomena include unequal electric and magnetic energies stored in plasmonic resonators, the small influence of dielectric losses on the Q-factors of magnetic plasmon resonances, the role of radiation and dissipation losses on the properties of plasmonic resonators, and the theoretical possibility of the existence of lightning plasma balls. Full article
(This article belongs to the Section Materials Physics)
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25 pages, 26496 KiB  
Article
Antibacterial Properties of PMMA/ZnO(NanoAg) Coatings for Dental Implant Abutments
by Ana Maria Gianina Rehner (Costache), Dana-Ionela Tudorache, Alexandra Cătălina Bîrcă, Adrian Ionuț Nicoară, Adelina-Gabriela Niculescu, Alina Maria Holban, Ariana Hudiță, Florentina Cornelia Bîclesanu, Paul Cătălin Balaure, Anna Maria Pangică, Alexandru Mihai Grumezescu and George-Alexandru Croitoru
Materials 2025, 18(2), 382; https://doi.org/10.3390/ma18020382 - 15 Jan 2025
Viewed by 1539
Abstract
Infections continue to pose significant challenges in dentistry, necessitating the development of innovative solutions that can effectively address these issues. This study focuses on creating coatings made from polymethyl methacrylate (PMMA) enriched with zinc oxide–silver composite nanoparticles, layered to Ti6Al4V–titanium alloy substrates. The [...] Read more.
Infections continue to pose significant challenges in dentistry, necessitating the development of innovative solutions that can effectively address these issues. This study focuses on creating coatings made from polymethyl methacrylate (PMMA) enriched with zinc oxide–silver composite nanoparticles, layered to Ti6Al4V–titanium alloy substrates. The application of these materials aims to create a solution for the abutments utilized in complete dental implant systems, representing the area most susceptible to bacterial infections. The nanoparticles were synthesized using a hydrothermal method, optimized through specific temperature and pressure parameters to achieve effective morphologies and sizes that enhance antibacterial efficacy. The layers were applied to the titanium substrate using the spin coating technique, chosen for its advantages and compatibility with the materials involved. Comprehensive analyses were conducted on the antimicrobial powders, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Furthermore, the PMMA-based coatings incorporating antimicrobial nanoparticles were evaluated to ensure uniformity and homogeneity across the titanium alloy surface by IR mapping and SBF immersion–SEM analysis. The antimicrobial activity of the samples was demonstrated with impressive results against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, as assessed through biofilm modulation studies. The biocompatibility of the samples was validated through in vitro cell-based assays, which demonstrated excellent compatibility between PMMA-based coatings and human preosteoblasts, confirming their potential suitability for future use in dental implants. Full article
(This article belongs to the Special Issue Advances in New Alloys, Polymers and Composites for Biomedical Applications)
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18 pages, 4252 KiB  
Article
Bilayer TiO2/Mo-BiVO4 Photoelectrocatalysts for Ibuprofen Degradation
by Martha Pylarinou, Elias Sakellis, Spiros Gardelis, Vassilis Psycharis, Marios G. Kostakis, Nikolaos S. Thomaidis and Vlassis Likodimos
Materials 2025, 18(2), 344; https://doi.org/10.3390/ma18020344 - 14 Jan 2025
Cited by 1 | Viewed by 1180
Abstract
Heterojunction formation between BiVO4 nanomaterials and benchmark semiconductor photocatalysts has been keenly pursued as a promising approach to improve charge transport and charge separation via interfacial electron transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical pollutants. In this work, a heterostructured TiO [...] Read more.
Heterojunction formation between BiVO4 nanomaterials and benchmark semiconductor photocatalysts has been keenly pursued as a promising approach to improve charge transport and charge separation via interfacial electron transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical pollutants. In this work, a heterostructured TiO2/Mo-BiVO4 bilayer photoanode was fabricated by the deposition of a mesoporous TiO2 overlayer using the benchmark P25 titania catalyst on top of Mo-doped BiVO4 inverse opal films as the supporting layer, which intrinsically absorbs visible light below 490 nm, while offering improved charge transport. A porous P25/Mo-BiVO4 bilayer structure was produced from the densification of the inverse opal underlayer after post-thermal annealing, which was evaluated on photocurrent generation in aqueous electrolyte and the photoelectrocatalytic degradation of the refractory anti-inflammatory drug ibuprofen under back-side illumination by visible and UV–Vis light. Significantly enhanced photoelectrochemical performance on both photocurrent density and pharmaceutical degradation was achieved for the bilayer structure with respect to the additive effect of the constituent layers, which was related to the improved light harvesting arising from the backscattering by the mesoporous TiO2 layer in combination with the favorable charge transfer at the TiO2/Mo-BiVO4 interface. Full article
(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))
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21 pages, 8799 KiB  
Article
Four-Dimensional Printing of β-Tricalcium Phosphate-Modified Shape Memory Polymers for Bone Scaffolds in Osteochondral Regeneration
by Izabella Rajzer, Anna Kurowska, Jarosław Janusz, Maksymilian Maślanka, Adam Jabłoński, Piotr Szczygieł, Janusz Fabia, Roman Novotný, Wojciech Piekarczyk, Magdalena Ziąbka and Jana Frankova
Materials 2025, 18(2), 306; https://doi.org/10.3390/ma18020306 - 11 Jan 2025
Cited by 1 | Viewed by 1137
Abstract
The use of scaffolds for osteochondral tissue regeneration requires an appropriate selection of materials and manufacturing techniques that provide the basis for supporting both cartilage and bone tissue formation. As scaffolds are designed to replicate a part of the replaced tissue and ensure [...] Read more.
The use of scaffolds for osteochondral tissue regeneration requires an appropriate selection of materials and manufacturing techniques that provide the basis for supporting both cartilage and bone tissue formation. As scaffolds are designed to replicate a part of the replaced tissue and ensure cell growth and differentiation, implantable materials have to meet various biological requirements, e.g., biocompatibility, biodegradability, and mechanical properties. Osteoconductive materials such as tricalcium phosphate ceramics and some biodegradable polymers appear to be a perfect choice. The present work evaluates the structural, mechanical, thermal, and functional properties of a shape memory terpolymer modified with β-tricalcium phosphate (β-TCP). A new approach is using the developed materials for 4D printing, with a particular focus on its applicability in manufacturing medical implants. In this study, the manufacturing parameters of the scaffold components were developed. The scaffolds were examined via scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and mechanical testing. The cytotoxicity result was obtained with an MTT assay, and the alkaline phosphatase (ALP) activity was measured. The structural and microstructural investigations confirmed the integration of β-TCP into the filament matrix and scaffolds. Thermal stability was enhanced as β-TCP delayed depolymerization of the polymer matrix. The shape memory studies demonstrated effective recovery. The in vitro cell culture studies revealed the significantly increased cell viability and alkaline phosphatase (ALP) activity of the β-TCP-modified terpolymer after 3 weeks. The developed terpolymer can be tailored for applications in which partial shape recovery is acceptable, such as bone scaffolds. Full article
(This article belongs to the Section Biomaterials)
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38 pages, 18491 KiB  
Review
Review of the Microstructural Impact on Creep Mechanisms and Performance for Laser Powder Bed Fusion Inconel 718
by Guillian Bryndza, Jérôme Tchoufang Tchuindjang, Fan Chen, Anne Marie Habraken, Héctor Sepúlveda, Víctor Tuninetti, Anne Mertens and Laurent Duchêne
Materials 2025, 18(2), 276; https://doi.org/10.3390/ma18020276 - 9 Jan 2025
Cited by 3 | Viewed by 1802
Abstract
Inconel 718 (IN718) is a polycrystalline nickel-based superalloy and one of the most widely used materials in the aerospace industry owing to its excellent mechanical performances at high temperatures, including creep resistance. Interest in additively manufactured components in aerospace is greatly increasing due [...] Read more.
Inconel 718 (IN718) is a polycrystalline nickel-based superalloy and one of the most widely used materials in the aerospace industry owing to its excellent mechanical performances at high temperatures, including creep resistance. Interest in additively manufactured components in aerospace is greatly increasing due to their ability to reduce material consumption, to manufacture complex parts, and to produce out-of-equilibrium microstructures, which can be beneficial for mechanical behavior. IN718’s properties are, however, very sensitive to microstructural features, which strongly depend on the manufacturing process and subsequent heat treatments. Additive manufacturing and, more specifically, Laser Powder Bed Fusion (LPBF) induces very high thermal gradients and anisotropic features due to its inherently directional nature, which largely defines the microstructure of the alloy. Hence, defining appropriate manufacturing parameters and heat treatments is critical to obtain appropriate mechanical behavior. This review aims to present the main microstructural features of IN718 produced by LPBF, the creep mechanisms taking place, the optimal microstructure for creep strength, and the most efficient heat treatments to yield such an optimized microstructure. Full article
(This article belongs to the Special Issue Quality, Microstructure and Properties of Metal Alloys (Second Volume))
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16 pages, 1625 KiB  
Article
Long-Term Clinical Study on Sandblasted–Acid-Etched Surface Dental Implants: 12-Year Follow-Up
by Eugenio Velasco-Ortega, Jesús Pato-Mourelo, Borja López-López, Loreto Monsalve-Guil, Jesús Moreno-Muñoz, José López-López, Enrique Núñez-Márquez, Nuno Matos Garrido, José Luis Rondón-Romero, Álvaro Jiménez-Guerra and Iván Ortiz-García
Materials 2025, 18(1), 183; https://doi.org/10.3390/ma18010183 - 4 Jan 2025
Viewed by 1141
Abstract
Sandblasting and acid etching are common procedures used to treat implant surfaces, enhancing osseointegration and improving clinical success rates. This clinical study aimed to evaluate the long-term outcomes of sandblasted and acid-etched implants. A total of 303 implants were placed in 114 partially [...] Read more.
Sandblasting and acid etching are common procedures used to treat implant surfaces, enhancing osseointegration and improving clinical success rates. This clinical study aimed to evaluate the long-term outcomes of sandblasted and acid-etched implants. A total of 303 implants were placed in 114 partially and totally edentulous patients using a two-stage surgical technique and an early loading protocol (6–8 weeks). Clinical findings for implants and prosthetics were evaluated over a 12-year follow-up period. A total of 12 implants (3.9%) failed, with 3 failures occurring during the healing period before loading and 9 due to peri-implantitis. The cumulative survival rate for all implants was 96.1%. A total of 156 prostheses were placed on 300 implants, 87 single crowns, 45 partial fixed bridges, 9 full-arch fixed restorations, and 15 overdentures. The mean marginal bone loss was 1.18 mm. (SD. 0.64 mm.). Thirty-nine implants (13%) in twenty-four patients exhibited peri-implantitis. Technical complications, including prosthetic screw loosening or fracture, ceramic chipping, and acrylic fractures, were observed in 24 subjects (21.1%). Sandblasted and acid-etched surface implants placed in the maxilla and mandible reported favorable outcomes and stable tissue conditions with an early loading protocol. Full article
(This article belongs to the Special Issue Advances in Dental Implants: Materials, Procedures and Clinical Response)
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40 pages, 9273 KiB  
Review
Revisiting Intercalation Anode Materials for Potassium-Ion Batteries
by María José Piernas-Muñoz and Maider Zarrabeitia
Materials 2025, 18(1), 190; https://doi.org/10.3390/ma18010190 - 4 Jan 2025
Cited by 3 | Viewed by 1730
Abstract
Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility [...] Read more.
Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility of providing high power and energy densities due to their faster K+ diffusion and very close reduction potential compared with Li+/Li. However, research on KIBs is still in its infancy, and hence, more investigation is required both at the materials level and at the device level. In this work, we focus on recent strategies to enhance the electrochemical properties of intercalation anode materials, i.e., carbon-, titanium-, and vanadium-based compounds. Hitherto, the most promising anode materials are those carbon-based, such as graphite, soft, or hard carbon, each with its advantages and disadvantages. Although a wide variety of strategies have been reported with excellent results, there is still a need to improve the standardization of the best carbon properties, electrode formulation, and electrolyte composition, given the impossibility of a direct comparison. Therefore, additional effort should be made to understand what are the crucial carbon parameters to develop a reference electrode and electrolyte formulation to further boost their performance and move a step forward in the commercialization of KIBs. Full article
(This article belongs to the Special Issue Advanced Anode Materials for Alkali-Ion Batteries)
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15 pages, 3362 KiB  
Article
Mechanical and Energy Evolution Characteristics of Fractured Sandstone Materials: A True Triaxial Experimental Study
by Guowen Sun, Yu Lu, Gun Huang, Qinming Liang and Xinyu Huang
Materials 2025, 18(1), 175; https://doi.org/10.3390/ma18010175 - 3 Jan 2025
Viewed by 638
Abstract
To investigate the mechanical and energy evolution characteristics of fractured rock under true triaxial stresses, true triaxial strength compression experiments on fractured sandstone were conducted with varying crack lengths and widths. The results indicate that under true triaxial stresses, the peak stress of [...] Read more.
To investigate the mechanical and energy evolution characteristics of fractured rock under true triaxial stresses, true triaxial strength compression experiments on fractured sandstone were conducted with varying crack lengths and widths. The results indicate that under true triaxial stresses, the peak stress of the rock exhibits a gradual decline with an increase in crack length and width. Meanwhile, crack initiation stress and crack damage stress of fractured sandstone also demonstrate a declining trend overall, and the influence of crack length on the characteristic stress (crack initiation stress and crack damage stress) of sandstone is more pronounced than that of crack width. According to the energy analysis results, the total strain energy of fractured sandstone gradually decreases with an increase in crack length and width. The results offer a theoretical foundation for the strength assessment and stability management of fractured rock materials during deep coal mining operations. Full article
(This article belongs to the Special Issue Microstructure, Characterization and Mechanical Properties of Coal and Coal-Like Materials (2nd Edition))
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13 pages, 11047 KiB  
Article
Memory Effect of Double Oxides Compared to Simple Ion Exchange for Controlled Fluoride Ion Capture and Release
by Asma Alazreg, Vladisav Tadić, Adela Egelja, Andrija Savić, Aleksandra Šaponjić, Marija M. Vuksanović and Radmila Jančić Heinemann
Materials 2025, 18(1), 162; https://doi.org/10.3390/ma18010162 - 3 Jan 2025
Cited by 1 | Viewed by 826
Abstract
A layered double hydroxide (LDH) containing Mg and Al was synthesized from a nitrate solution using a coprecipitation method. The resulting material exhibited a homogeneous structure, which, upon calcination at 450 °C, was converted into a layered double oxide (LDO). When rehydrated in [...] Read more.
A layered double hydroxide (LDH) containing Mg and Al was synthesized from a nitrate solution using a coprecipitation method. The resulting material exhibited a homogeneous structure, which, upon calcination at 450 °C, was converted into a layered double oxide (LDO). When rehydrated in a fluoride-containing aqueous solution, the original hydroxide structure was successfully regenerated, demonstrating the LDH’s memory effect. During this transformation, fluoride anions from the solution were incorporated into the interlayer galleries to maintain electroneutrality, as confirmed by energy-dispersive X-ray spectroscopy (EDS) analysis. Separately, the process was tested in the presence of ethanol, which significantly enhanced the incorporation of fluoride ions into the interlayer spaces. The material’s potential for controlled fluoride release was evaluated by monitoring its release into demineralized water. For comparison, a simple ion-exchange process was carried out using the as-synthesized MgAl LDH. The memory effect mechanism displayed a notably higher fluoride incorporation capacity compared to the ion-exchange process. Among all the specimens, the sample reconstructed in the presence of ethanol exhibited the highest fluoride ion content. Fluoride release studies revealed a two-phase pattern: an initial rapid release within the first three hours, followed by a substantially slower release over time. Full article
(This article belongs to the Special Issue Graphene and Other 2D Layered Nanomaterials and Hybrid Structures: Synthesis, Properties and Applications (Volume II))
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21 pages, 5415 KiB  
Article
Hierarchical 3D FeCoNi Alloy/CNT @ Carbon Nanofiber Sponges as High-Performance Microwave Absorbers with Infrared Camouflage
by Yifan Fei, Junya Yao, Wei Cheng and Wenling Jiao
Materials 2025, 18(1), 113; https://doi.org/10.3390/ma18010113 - 30 Dec 2024
Viewed by 858
Abstract
Microwave absorbers with infrared camouflage are highly desirable in military fields. Self-supporting 3D architectures with tailorable shapes, composed of FeCoNi alloy/carbon nanotubes (CNTs) @ carbon nanofibers (CNFs), were fabricated in this study. On the one hand, multiple loss mechanisms were introduced into the [...] Read more.
Microwave absorbers with infrared camouflage are highly desirable in military fields. Self-supporting 3D architectures with tailorable shapes, composed of FeCoNi alloy/carbon nanotubes (CNTs) @ carbon nanofibers (CNFs), were fabricated in this study. On the one hand, multiple loss mechanisms were introduced into the high-elastic sponges. Controllable space conductive networks caused by the in situ growth of CNTs on the CNFs contributed to the effective dielectric and resistance loss. Moreover, the uniformly distributed magnetic alloy nanoparticles (NPs) with dense magnetic coupling resulted in magnetic loss. On the other hand, heterogeneous interfaces were constructed by multicomponent engineering, causing interfacial polarization and polarization loss. Furthermore, the internal structures of sponges were optimized by regulating the alloy NPs sizes and the growth state of CNTs, then tuning the impedance matching and microwave absorption. Therefore, the high-elastic sponges with ultra-low density (7.6 mg·cm−3) were found to have excellent radar and infrared-compatible stealth properties, displaying a minimum refection loss (RLmin) of −50.5 dB and a maximum effective absorption bandwidth (EABmax) of 5.36 GHz. Moreover, the radar stealth effect of the sponges was evaluated by radar cross-section (RCS) simulation, revealing that the multifunctional sponges have a promising prospect in military applications. Full article
(This article belongs to the Special Issue Advances in Electrostatic Spinning Micro and Nano Fibers)
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17 pages, 3346 KiB  
Article
The Use of 3D Printing Filaments to Build Moisture Sensors in Porous Materials
by Magdalena Paśnikowska-Łukaszuk, Joanna Szulżyk-Cieplak, Magda Wlazło, Jarosław Zubrzycki, Ewa Łazuka, Arkadiusz Urzędowski and Zbigniew Suchorab
Materials 2025, 18(1), 115; https://doi.org/10.3390/ma18010115 - 30 Dec 2024
Cited by 1 | Viewed by 921
Abstract
This study explores the application of materials used in 3D printing to manufacture the housings of non-invasive sensors employed in measurements using a TDR (Time Domain Reflectometry) meter. The research investigates whether sensors designed with 3D printing technology can serve as viable alternatives [...] Read more.
This study explores the application of materials used in 3D printing to manufacture the housings of non-invasive sensors employed in measurements using a TDR (Time Domain Reflectometry) meter. The research investigates whether sensors designed with 3D printing technology can serve as viable alternatives to conventional invasive and non-invasive sensors. This study focuses on innovative approaches to designing humidity sensors, utilizing Fused Deposition Modeling (FDM) technology to create housings for non-invasive sensors compatible with TDR devices. The paper discusses the use of 3D modeling technology in sensor design, with particular emphasis on materials used in 3D printing, notably polylactic acid (PLA). Environmental factors, such as moisture in building materials, are characterized, and the need for dedicated sensor designs is highlighted. The software utilized in the 3D modeling and printing processes is also described. The Materials and Methods Section provides a detailed account of the construction process for the non-invasive sensor housing and the preparation for moisture measurement in silicate materials using the designed sensor. A prototype sensor was successfully fabricated through 3D printing. Using the designed sensor, measurements were conducted on silicate samples soaked in aqueous solutions with water absorption levels ranging from 0% to 10%. Experimental validation involved testing silicate samples with the prototype sensor to evaluate its effectiveness. The electrical permittivity of the material was calculated, and the root-mean-square error (RMSE) was determined using classical computational methods and machine learning techniques. The RMSE obtained using the classical method was 0.70. The results obtained were further analyzed using machine learning models, including Gaussian Process Regression (GPR) and Support Vector Machine (SVM). The GPR model achieved an RMSE of 0.15, while the SVM model yielded an RMSE of 0.25. These findings confirm the sensor’s effectiveness and its potential for further research and practical applications. Full article
(This article belongs to the Special Issue 3D-Printed Composite Structures: Design, Properties and Application)
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14 pages, 2561 KiB  
Article
Surface Hydrophilic Modification of Polypropylene by Nanosecond Pulsed Ar/O2 Dielectric Barrier Discharge
by Yang Zhou, Zhi Fang, Yi Zhang, Tingting Li and Feng Liu
Materials 2025, 18(1), 95; https://doi.org/10.3390/ma18010095 - 29 Dec 2024
Cited by 1 | Viewed by 1058
Abstract
Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux [...] Read more.
Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux reduction, which greatly hinders the applications of PP membranes. Dielectric barrier discharge (DBD) is an effective technique for surface modification of materials because it generates a large area of low-temperature plasma at atmospheric pressure. In this study, O2 was added to nanosecond pulsed Ar DBD to increase its reactivity. Electrical and optical diagnostic techniques were used to study the discharge characteristics of the DBD at varying O2 contents. The uniformity of the discharge was quantitatively analyzed using the observed discharge images. Water contact angle measurements were used to assess the surface hydrophilicity of polypropylene. The surface morphology and chemical composition of the PP materials before and after treatment were analyzed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the moderate addition of O2 enhances surface hydrophilicity and the uniformity of the modification. By increasing the O2 addition from 0% to 0.1%, the average power increased from 4.19 W to 5.79 W, and the energy efficiency increased from 17.78% to 21.51%. The water contact angle of the DBD-treated PP showed a tendency to decrease and then increase with increasing O2 content, with the optimum O2 addition determined to be 0.1%. Under this condition, the water contact angle of the PP surface decreased by 31.88°, which is 52.31% lower than the untreated surface. O2 increases the number of oxygen-containing polar groups (-OH, C=O, and O-C=O) on the surface of the material, and deepens and densifies the grooves on the surface of the PP material, resulting in an increase in the hydrophilicity of the PP surface. Full article
(This article belongs to the Special Issue Advances in Design and Characterization of Graded and Hierarchical Honeycomb Materials)
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25 pages, 7189 KiB  
Article
Design Optimization of the Mechanics of a Metamaterial-Based Prosthetic Foot
by Agata Mrozek-Czajkowska and Tomasz Stręk
Materials 2025, 18(1), 96; https://doi.org/10.3390/ma18010096 - 29 Dec 2024
Viewed by 850
Abstract
This paper is dedicated to the analysis of a foot prosthesis optimization process, with a particular focus on the application of optimization algorithms and unconventional materials, such as auxetic materials. The study aims to enhance prosthesis performance by minimizing the difference between the [...] Read more.
This paper is dedicated to the analysis of a foot prosthesis optimization process, with a particular focus on the application of optimization algorithms and unconventional materials, such as auxetic materials. The study aims to enhance prosthesis performance by minimizing the difference between the ground reaction force generated by the prosthetic foot and that of a natural limb. In the initial part of the study, the basic topics concerning the parameterization of the foot prosthesis geometry and the preparation of a finite element model for human gait are discussed. In the subsequent part of the study, the focus is on the optimization process, in which algorithms were applied to adjust the prosthesis structure to the patient’s individual needs. The optimization process utilized a finite element method gait model. After validating the FEM, an algorithm generating the prosthesis geometry based on the given parameters was developed. These parameters were optimized using the VOA, comparing FEM gait model data on vertical ground reaction force with experimental results. The results of the foot prosthesis optimization are presented through a comparison of different structural models. The study also demonstrates the application of auxetic materials, which, due to their unique mechanical properties, can enhance foot prosthesis efficiency. Simulations were performed using multi-material topology optimization. The results obtained for different gait phases were compared. Full article
(This article belongs to the Special Issue Modelling of Deformation Characteristics of Materials or Structures)
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15 pages, 3877 KiB  
Article
Unveiling the Influence of Hot Carriers on Photovoltage Formation in Perovskite Solar Cells
by Muhammad Mujahid, Aurimas Čerškus, Jonas Gradauskas, Asta Grigucevičienė, Raimondas Giraitis, Konstantinas Leinartas, Andžej Lučun, Kazimieras Petrauskas, Algirdas Selskis, Algirdas Sužiedėlis, Aldis Šilėnas, Edmundas Širmulis and Steponas Ašmontas
Materials 2025, 18(1), 85; https://doi.org/10.3390/ma18010085 - 28 Dec 2024
Viewed by 883
Abstract
The experimental and theoretical study of photovoltage formation in perovskite solar cells under pulsed laser excitation at 0.53 μm wavelength is presented. Two types of solar cells were fabricated on the base of cesium-containing triple cation perovskite films: (1) Csx(FA0.83 [...] Read more.
The experimental and theoretical study of photovoltage formation in perovskite solar cells under pulsed laser excitation at 0.53 μm wavelength is presented. Two types of solar cells were fabricated on the base of cesium-containing triple cation perovskite films: (1) Csx(FA0.83MA0.17)(1−x)Pb(I0.83Br0.17)3 and (2) Csx(FA0.83MA0.17)(1−x)Pb0.8Sn0.2(I0.83Br0.17)3. It is found that photovoltage across the solar cells consists of two components, U = Uph + Uf. The first one, Uph, is the traditional photovoltage arising due to laser radiation-induced electron-hole pair generation. The second one, Uf, is the fast component following the laser pulse and has a polarity opposite to that of Uph. It is shown that the fast photovoltage component results from the laser radiation-caused heating of free carriers. The transient photovoltage measurements show that the values of the fast component Uf are nearly the same in both types of perovskite solar cells. The magnitude of the traditional photovoltage of mixed Pb-Sn perovskite solar cells is lower than that of Pb-based cells. Full article
(This article belongs to the Special Issue Advances in Photoelectric Materials: Preparation, Properties, and Applications)
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20 pages, 9184 KiB  
Article
Tribomechanical Properties of Glazes for Ceramic Tiles: A Novel Protocol for Their Characterization
by Riccardo Fabris, Giulia Masi, Denia Mazzini, Leonardo Sanseverino and Maria Chiara Bignozzi
Materials 2025, 18(1), 60; https://doi.org/10.3390/ma18010060 - 27 Dec 2024
Viewed by 3817
Abstract
The aim of the work is to design and validate a characterization protocol for glazes used in the ceramic tile industry to lead manufacturers and researchers towards the formulation of glazes with enhanced wear resistance properties. The focus of the protocol is addressed [...] Read more.
The aim of the work is to design and validate a characterization protocol for glazes used in the ceramic tile industry to lead manufacturers and researchers towards the formulation of glazes with enhanced wear resistance properties. The focus of the protocol is addressed to determine surface parameters that strongly depend on glaze formulation and firing temperature. This protocol includes analytical (e.g., thermal analysis, Vickers microhardness, microstructural investigation, etc.) and technological tests (i.e., impact resistance and surface abrasion resistance test), the latter carried out on ceramic tile samples where four different glazes have been applied. The characterization protocol set in this paper highlights the importance of using both analytical and technological tests for glaze investigations and provides threshold values for specific parameters useful in developing glass-ceramic glazes with enhanced mechanical and tribological properties. Full article
(This article belongs to the Special Issue Sintering of Ceramic Materials)
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22 pages, 9096 KiB  
Article
Assessment of Steel Storage Tank Thickness Obtained from the API 650 Design Procedure Through Nonlinear Dynamic Analysis, Accounting for Large Deformation Effects
by Sobhan Fallah Daryavarsari and Roberto Nascimbene
Materials 2025, 18(1), 66; https://doi.org/10.3390/ma18010066 - 27 Dec 2024
Cited by 1 | Viewed by 1843
Abstract
This study evaluates the API 650 design procedure for steel storage tanks, incorporating nonlinear dynamic analysis with large deformation effects. Focusing on seismic vulnerability, the case study examines storage tanks proposed for construction in Naples, Italy, assessing their performance under site-specific seismic conditions. [...] Read more.
This study evaluates the API 650 design procedure for steel storage tanks, incorporating nonlinear dynamic analysis with large deformation effects. Focusing on seismic vulnerability, the case study examines storage tanks proposed for construction in Naples, Italy, assessing their performance under site-specific seismic conditions. A target spectrum and 20 earthquake records were selected to reflect regional seismic characteristics. Initial tank thicknesses were calculated using API 650 guidelines and subsequently analyzed through nonlinear time-history simulations in SAP2000. Results reveal that thicknesses derived from API 650s linear average spectrum equations are insufficient for real seismic demands. Through a trial-and-error methodology, optimal thicknesses were determined to ensure satisfactory performance across all seismic records. Key findings highlight significant variations in mode participation, the frequent occurrence of elephant-foot buckling in tanks with lower H/R ratios, and the limitations of linear spectral analysis for realistic earthquake scenarios. Given the vital role of storage tanks in the oil and gas industry, this study emphasizes the need to integrate nonlinear time history analysis into design processes to enhance seismic resilience, particularly in high-risk regions. Full article
(This article belongs to the Special Issue Advances in the Nonlinear Vibration and Structure Dynamics of Composite Materials)
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26 pages, 14474 KiB  
Article
Development of a Stable Process for Wire Embedding in Fused Filament Fabrication Printing Using a Geometric Correction Model
by Valentin Wilhelm Mauersberger, Fabian Ziervogel, Linda Weisheit, Lukas Boxberger and Welf-Guntram Drossel
Materials 2025, 18(1), 41; https://doi.org/10.3390/ma18010041 - 26 Dec 2024
Viewed by 773
Abstract
Using a newly developed tool head with an additional rotational axis and a wire feed, wires can be directly processed in the fused filament fabrication (FFF) process. Thus, electrical structures such as conductive paths, coils, heating elements, or sensors can be integrated into [...] Read more.
Using a newly developed tool head with an additional rotational axis and a wire feed, wires can be directly processed in the fused filament fabrication (FFF) process. Thus, electrical structures such as conductive paths, coils, heating elements, or sensors can be integrated into polymer parts. However, the accuracy of the wire deposition in curved sections of the print track is insufficient. To improve the wire position, a geometric correction model was set up, converted into G-code, and validated using test prints for different wire parameters. For this, a sample of printed arcs was evaluated regarding wire position and embedding quality using various visual methods. This also determined the optimal cooling time for the model. The process parameters extrusion coefficient and feed were then varied to identify optimal process parameters for a stable and at the same time efficient process. By varying the wire (copper, constantan) and polymer material (PLA, PETG), the model was checked for general validity. It was found that the position of the ø 0.2 mm wire can be improved with the correction model. Different sets of parameters can be found that enable good quality of embedding and wire position. Full article
(This article belongs to the Special Issue Current and Future Trends in Additive Manufacturing)
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28 pages, 13465 KiB  
Article
Innovative Approaches on the Estimation of the Effective Permittivity of Fibrous Media
by Jesus Nain Camacho Hernandez and Guido Link
Materials 2025, 18(1), 14; https://doi.org/10.3390/ma18010014 - 24 Dec 2024
Viewed by 744
Abstract
Estimating the effective permittivity of anisotropic fibrous media is critical for advancing electromagnetic applications, requiring detailed microstructural and orientation analyses. This study introduces innovative approaches for disclosing the orientation and microstructure of fibers, leading to mixing relations. It particularly focuses on two specific [...] Read more.
Estimating the effective permittivity of anisotropic fibrous media is critical for advancing electromagnetic applications, requiring detailed microstructural and orientation analyses. This study introduces innovative approaches for disclosing the orientation and microstructure of fibers, leading to mixing relations. It particularly focuses on two specific fiber configurations: 1. wave-curved fibers and 2. a collection of interconnected fibers. The first approach uses sinusoidal wave fibers, considering their curvature and direction. Conversely, the approach for the interconnected fibers operates on the principle of representing fibers as a collection of straight segments. Investigations on fibrous media for both approaches were performed using numerical calculations at the microwave frequency of 2.45 GHz. Each fibrous medium was treated as an effective medium by using fibers significantly smaller than the microwave wavelength. A thorough comparison was made between the proposed mixing relations, numerical data, and state-of-the-art mixing relations to assess their consistency and validity. The comparison of the proposed approaches with traditional models shows an improved accuracy of up to 70% and 8% for the real and imaginary components of the permittivity, respectively. Additionally, the root-mean-square errors were determined as 0.001 + j0.003 and 0.001 – j0.007 for the sinusoidal and interconnected straight fibers approaches, respectively. In addition, a woven alumina fabric was used to compare the experimental resonance frequency with that from simulations using the permittivity of the fabric estimated by the interconnected straight fibers approach. These findings advance the predictive accuracy of permittivity estimation in fibrous media, providing a robust foundation for engineering applications. Full article
(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Advanced Materials Characterization)
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17 pages, 5985 KiB  
Article
The Effect of the Chamber-Filling Ratio in Vibratory Shot Peening on Selected Surface Layer Properties of 30HGSA
by Agnieszka Skoczylas and Kazimierz Zaleski
Materials 2025, 18(1), 8; https://doi.org/10.3390/ma18010008 - 24 Dec 2024
Viewed by 526
Abstract
This study investigated the influence of the filling ratio of the working chamber and ball diameter in vibratory shot peening (VSP) on select properties of the surface layer. The tested material was 30HGSA steel, which is effectively used in the aviation industry. The [...] Read more.
This study investigated the influence of the filling ratio of the working chamber and ball diameter in vibratory shot peening (VSP) on select properties of the surface layer. The tested material was 30HGSA steel, which is effectively used in the aviation industry. The following were analyzed: the surface roughness parameters, the shape of the Abbott–Firestone curve, the bearing area ratio Smr(c=50%), the microhardness distribution, the microhardness on the surface, and the residual stress σ on the surface. A change in the ratio of peaks and valleys in the maximum height of the profile was observed. After VSP, the valleys were dominant over the peaks. The most favorable values of the analyzed roughness parameters (Sz, Sp, and Sv) were obtained for d = 9.4 mm and kd = 33%. The bearing area ratio Smr(c=50%) was approximately 50 times higher than before VSP (the most favorable for d = 9.4 mm and kd = 33%). The largest thickness of the strengthened layer of 200 μm and the greatest increase in the microhardness equal to ΔHV 0.05 = 109 were obtained after VSP was conducted using the ball diameter d = 14.3 mm kd = 33%. Regardless of the VSP conditions, the absolute value of compressive stresses increased; the highest σ stresses were obtained for d = 3.0 mm and kd = 33%, and they were 88% higher than before the treatment. It was concluded that the recommended chamber-filling ratio for beneficial properties is kd = 33%. Full article
(This article belongs to the Special Issue Material Surface Topography Measurement, Analysis and Characterization)
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15 pages, 11668 KiB  
Article
Analysis of the Properties of Anticorrosion Systems Used for Structural Component Protection in Truck Trailers
by Wojciech Skotnicki and Dariusz Jędrzejczyk
Materials 2024, 17(24), 6303; https://doi.org/10.3390/ma17246303 - 23 Dec 2024
Viewed by 802
Abstract
The article compares the properties of coatings (cataphoretic, hot-dip zinc, and thermo-diffusion zinc) applied to steel components used in the automotive industry. The research focused on the analysis of corrosion resistance, hardness measurements, and tribological properties conducted on steel guides used in trailer [...] Read more.
The article compares the properties of coatings (cataphoretic, hot-dip zinc, and thermo-diffusion zinc) applied to steel components used in the automotive industry. The research focused on the analysis of corrosion resistance, hardness measurements, and tribological properties conducted on steel guides used in trailer and truck body structures as well as fasteners (M12 × 40 bolts). The base surfaces were cleaned chemically. Corrosion resistance was tested in a salt chamber, while coating thickness was measured using the magnetic induction method. Coating hardness (HV 0.02) was assessed with a microhardness tester, and tribological properties were tested under dry friction conditions. The results showed that the zinc coatings demonstrated corrosion resistance far superior to paint coatings. Full article
(This article belongs to the Special Issue Metal Coatings for Wear and Corrosion Applications (Second Edition))
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20 pages, 37498 KiB  
Article
Analysis of the Deburring Efficiency of EN-AW 7075 Aluminum Alloy Parts with Complex Geometric Shapes Considering the Tool Path Strategy During Multi-Axis Brushing
by Jakub Matuszak, Andrzej Kawalec and Michał Gdula
Materials 2024, 17(24), 6267; https://doi.org/10.3390/ma17246267 - 21 Dec 2024
Viewed by 810
Abstract
The paper presents the results of an analysis of the effect of brushing on the edge condition of workpieces with complex geometric shapes, formed during milling, on a five-axis DMU 100 monoBLOCK machining center. A set of EN-AW 7075 aluminum alloy specimens with [...] Read more.
The paper presents the results of an analysis of the effect of brushing on the edge condition of workpieces with complex geometric shapes, formed during milling, on a five-axis DMU 100 monoBLOCK machining center. A set of EN-AW 7075 aluminum alloy specimens with curvilinear edges requiring multi-axis machining was prepared. The change of edge condition after the milling process was realized using Xebec tools with flexible ceramic fibers. The effects of brush fiber type and parameters related to tool design were analyzed. Different brushing strategies were employed on the five-axis machining center. It was shown that, for curvilinear edges, there were different effects for concave and convex edges depending on the employed tool strategy, including the type of tool, its configuration, and its orientation towards the workpiece. For a lead angle of β = 0°, the machined edge was characterized by variable chamfer widths, in spite of maintaining other machining parameters constant. The use of a lead angle β > 0 produced a stable edge with repeatable characteristics. The range of fiber interaction increased with increasing the lead angle and fiber working length. Full article
(This article belongs to the Special Issue Material Surface Topography Measurement, Analysis and Characterization)
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18 pages, 7895 KiB  
Article
Construction of Z-Scheme ZIF67/NiMoO4 Heterojunction for Enhanced Photocatalytic Degradation of Antibiotic Pollutants
by Kandasamy Sasikumar, Ramar Rajamanikandan and Heongkyu Ju
Materials 2024, 17(24), 6225; https://doi.org/10.3390/ma17246225 - 20 Dec 2024
Cited by 2 | Viewed by 838
Abstract
The rational design of heterojunction photocatalysts enabling fast transportation and efficient separation of photoexcited charge carriers is the key element in visible light-driven photocatalyst systems. Herein, we develop a unique Z-scheme heterojunction consisting of NiMoO4 microflowers (NMOF) and ZIF67, referred to as [...] Read more.
The rational design of heterojunction photocatalysts enabling fast transportation and efficient separation of photoexcited charge carriers is the key element in visible light-driven photocatalyst systems. Herein, we develop a unique Z-scheme heterojunction consisting of NiMoO4 microflowers (NMOF) and ZIF67, referred to as ZINM (composite), for the purpose of antibiotic degradation. ZIF67 was produced by a solution process, whereas NMOF was synthesized via coprecipitation with a glycine surfactant. The NMOF exhibited a monoclinic phase with a highly oriented, interconnected sheet-like morphology. The ZINM showed better optical and charge transfer characteristics than its constituents, ZIF67 and NiMoO4. Consequently, the developed heterojunction photocatalysts exhibited superior photocatalytic redox capability; the ZINM30 (the composite with 30 wt.% of NiMoO4 loaded) could degrade 91.67% of tetracycline and 86.23% of norfloxacin within 120 min. This enhanced photocatalytic activity was attributable to the reduced bandgap (Egap = 2.01 eV), unique morphology, high specific surface area (1099.89 m2/g), and intimate contact between ZIF67 and NiMoO4, which facilitated the establishment of the Z-scheme heterojunction. Active species trapping tests verified that •O2− and h+ were the primary species, supporting the proposed degradation mechanism. This work highlights a valid Z-scheme ZIF67/NiMoO4 heterojunction system for efficient carrier separation and, therefore, enhanced photocatalytic degradation of antibiotics. Full article
(This article belongs to the Special Issue Research Progress in Nanomaterials for Environmental Remediation)
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29 pages, 6836 KiB  
Review
Advanced Characterization of Solid-State Battery Materials Using Neutron Scattering Techniques
by Eric Novak, Luke Daemen and Niina Jalarvo
Materials 2024, 17(24), 6209; https://doi.org/10.3390/ma17246209 - 19 Dec 2024
Viewed by 1272
Abstract
Advanced batteries require advanced characterization techniques, and neutron scattering is one of the most powerful experimental methods available for studying next-generation battery materials. Neutron scattering offers a non-destructive method to probe the complex structural and chemical processes occurring in batteries during operation in [...] Read more.
Advanced batteries require advanced characterization techniques, and neutron scattering is one of the most powerful experimental methods available for studying next-generation battery materials. Neutron scattering offers a non-destructive method to probe the complex structural and chemical processes occurring in batteries during operation in truly in situ/in operando measurements with a high sensitivity to battery-relevant elements such as lithium. Neutrons have energies comparable to the energies of excitations in materials and wavelengths comparable to atomic distances in the solid state, thus giving access to study structural and dynamical properties of materials on an atomic scale. In this review, a broad overview of selected neutron scattering techniques is presented to illustrate how neutron scattering can be used to gain invaluable information of solid-state battery materials, with a focus on in situ/in operando methods. These techniques span multiple decades of length and time scales to uncover the complex processes taking place fundamentally on the atomic scale and to determine how these processes impact the macroscale properties and performance of functional battery systems. This review serves the solid-state battery research community by examining how the unique capabilities of neutron scattering can be applied to answer critical and unresolved questions of materials research in this field. A thorough and broad perspective is provided with numerous practical examples showing these techniques in action for battery research. Full article
(This article belongs to the Special Issue Local Structure Characterization for Complex Functional Materials)
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