Materials

22 pages, 8107 KiB

Open AccessEditor’s ChoiceReview

Sol–Gel Photonic Glasses: From Material to Application

by Giancarlo C. Righini, Cristina Armellini, Maurizio Ferrari, Alice Carlotto, Alessandro Carpentiero, Andrea Chiappini, Alessandro Chiasera, Anna Lukowiak, Thi Ngoc Lam Tran and Stefano Varas

Materials 2023, 16(7), 2724; https://doi.org/10.3390/ma16072724 - 29 Mar 2023

Cited by 8 | Viewed by 3588

Abstract

In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention [...] Read more.

In this review, we present a short overview of the development of sol–gel glasses for application in the field of photonics, with a focus on some of the most interesting results obtained by our group and collaborators in that area. Our main attention is devoted to silicate glasses of different compositions, which are characterized by specific optical and spectroscopic properties for various applications, ranging from luminescent systems to light-confining structures and memristors. In particular, the roles of rare-earth doping, matrix composition, the densification process and the fabrication protocol on the structural, optical and spectroscopic properties of the developed photonic systems are discussed through appropriate examples. Some achievements in the fabrication of oxide sol–gel optical waveguides and of micro- and nanostructures for the confinement of light are also briefly discussed. Full article

(This article belongs to the Special Issue Glassy Materials: From Preparation to Application)

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13 pages, 4976 KiB

Open AccessEditor’s ChoiceArticle

Vibration and Bandgap Behavior of Sandwich Pyramid Lattice Core Plate with Resonant Rings

by Chengfei Li, Zhaobo Chen and Yinghou Jiao

Materials 2023, 16(7), 2730; https://doi.org/10.3390/ma16072730 - 29 Mar 2023

Cited by 16 | Viewed by 2646

Abstract

The vibration suppression performance of the pyramid lattice core sandwich plates is receiving increasing attention and needs further investigation for technical upgrading of potential engineering applications. Inspired by the localized resonant mechanism of the acoustic metamaterials and considering the integrity of the lattice [...] Read more.

The vibration suppression performance of the pyramid lattice core sandwich plates is receiving increasing attention and needs further investigation for technical upgrading of potential engineering applications. Inspired by the localized resonant mechanism of the acoustic metamaterials and considering the integrity of the lattice sandwich plate, we reshaped a sandwich pyramid lattice core with resonant rings (SPLCRR). Finite element (FE) models are built up for the calculations of the dispersion curves and vibration transmission. The validity of the bandgap of the SPLCRR and remarkable vibration suppression are verified by experimental observations and the numerical methods. Furthermore, the effects of geometric parameters, material parameters and period parameters on the bandgaps of the SPLCRR are systematically investigated, which offers a deeper understanding of the underlying mechanism of bandgap and helps the SPLCRR structure meet the technological update requirements of practical engineering design. Full article

(This article belongs to the Section Mechanics of Materials)

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21 pages, 8593 KiB

Open AccessEditor’s ChoiceArticle

Durability and Thermal Behavior of Functional Paints Formulated with Recycled-Glass Hollow Microspheres of Different Size

by Massimo Calovi and Stefano Rossi

Materials 2023, 16(7), 2678; https://doi.org/10.3390/ma16072678 - 28 Mar 2023

Cited by 6 | Viewed by 2737

Abstract

This study aims to assess the effect of hollow glass microspheres of different sizes derived from glass industry waste on the durability and thermal behavior of waterborne paint. The coatings were characterized by electron microscopy to investigate the distribution of the spheres and [...] Read more.

This study aims to assess the effect of hollow glass microspheres of different sizes derived from glass industry waste on the durability and thermal behavior of waterborne paint. The coatings were characterized by electron microscopy to investigate the distribution of the spheres and their influence on the layer morphology. The impact of the various glassy spheres on the mechanical feature of the coatings was assessed using the Buchholz hardness test and the Scrub abrasion test. The role of the spheres in altering the durability of the samples was analyzed by the salt spray exposure test and the electrochemical impedance spectroscopy measurements. Finally, a specific accelerated degradation test was carried out to explore the evolution of the thermal behavior of the composite coatings. Ultimately, this work revealed the pros and cons of using hollow glass spheres as a multifunctional paint filler, highlighting the size of the spheres as a key parameter. For example, spheres with adequate size (25–44 µm), totally embedded in the polymeric matrix, are able to reduce the thermal conductivity of the coating avoiding local heat accumulation phenomena. Full article

(This article belongs to the Special Issue Methodology of the Design and Testing of Composite Structures)

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14 pages, 2102 KiB

Open AccessEditor’s ChoiceArticle

Modification of Anodic Titanium Oxide Bandgap Energy by Incorporation of Tungsten, Molybdenum, and Manganese In Situ during Anodization

by Marta Michalska-Domańska, Katarzyna Prabucka and Mateusz Czerwiński

Materials 2023, 16(7), 2707; https://doi.org/10.3390/ma16072707 - 28 Mar 2023

Cited by 3 | Viewed by 2486

Abstract

In this research, we attempted to modify the bandgap of anodic titanium oxide by in situ incorporation of selected elements into the anodic titanium oxide during the titanium anodization process. The main aim of this research was to obtain photoactivity of anodic titanium [...] Read more.

In this research, we attempted to modify the bandgap of anodic titanium oxide by in situ incorporation of selected elements into the anodic titanium oxide during the titanium anodization process. The main aim of this research was to obtain photoactivity of anodic titanium oxide over a broader sunlight wavelength. The incorporation of the selected elements into the anodic titanium oxide was proved. It was shown that the bandgap values of anodic titanium oxides made at 60 V are in the visible region of sunlight. The smallest bandgap value was obtained for anodic titanium oxide modified by manganese, at 2.55 eV, which corresponds to a wavelength of 486.89 nm and blue color. Moreover, it was found that the pH of the electrolyte significantly affects the thickness of the anodic titanium oxide layer. The production of barrier oxides during the anodizing process with properties similar to coatings made by nitriding processes is reported for the first time. Full article

(This article belongs to the Special Issue Anodized Materials and Their Applications)

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25 pages, 14854 KiB

Open AccessEditor’s ChoiceReview

The Characteristic Microstructures and Properties of Steel-Based Alloy via Additive Manufacturing

by Chunlei Shang, Honghui Wu, Guangfei Pan, Jiaqi Zhu, Shuize Wang, Guilin Wu, Junheng Gao, Zhiyuan Liu, Ruidi Li and Xinping Mao

Materials 2023, 16(7), 2696; https://doi.org/10.3390/ma16072696 - 28 Mar 2023

Cited by 8 | Viewed by 3503

Abstract

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy [...] Read more.

Differing from metal alloys produced by conventional techniques, metallic products prepared by additive manufacturing experience distinct solidification thermal histories and solid−state phase transformation processes, resulting in unique microstructures and superior performance. This review starts with commonly used additive manufacturing techniques in steel−based alloy and then some typical microstructures produced by metal additive manufacturing technologies with different components and processes are summarized, including porosity, dislocation cells, dendrite structures, residual stress, element segregation, etc. The characteristic microstructures may exert a significant influence on the properties of additively manufactured products, and thus it is important to tune the components and additive manufacturing process parameters to achieve the desired microstructures. Finally, the future development and prospects of additive manufacturing technology in steel are discussed. Full article

(This article belongs to the Special Issue Advances in the Experimentation and Numerical Modeling of Material Joining Processes)

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21 pages, 3548 KiB

Open AccessEditor’s ChoiceReview

Application of Nano-Crystalline Diamond in Tribology

by Yue Xia, Yunxiang Lu, Guoyong Yang, Chengke Chen, Xiaojun Hu, Hui Song, Lifen Deng, Yuezhong Wang, Jian Yi and Bo Wang

Materials 2023, 16(7), 2710; https://doi.org/10.3390/ma16072710 - 28 Mar 2023

Cited by 11 | Viewed by 3401

Abstract

Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and [...] Read more.

Nano-crystalline diamond has been extensively researched and applied in the fields of tribology, optics, quantum information and biomedicine. In virtue of its hardness, the highest in natural materials, diamond outperforms the other materials in terms of wear resistance. Compared to traditional single-crystalline and poly-crystalline diamonds, nano-crystalline diamond consists of disordered grains and thus possesses good toughness and self-sharpening. These merits render nano-crystalline diamonds to have great potential in tribology. Moreover, the re-nucleation of nano-crystalline diamond during preparation is beneficial to decreasing surface roughness due to its ultrafine grain size. Nano-crystalline diamond coatings can have a friction coefficient as low as single-crystal diamonds. This article briefly introduces the approaches to preparing nano-crystalline diamond materials and summarizes their applications in the field of tribology. Firstly, nano-crystalline diamond powders can be used as additives in both oil- and water-based lubricants to significantly enhance their anti-wear property. Nano-crystalline diamond coatings can also act as self-lubricating films when they are deposited on different substrates, exhibiting excellent performance in friction reduction and wear resistance. In addition, the research works related to the tribological applications of nano-crystalline diamond composites have also been reviewed in this paper. Full article

(This article belongs to the Special Issue Advances in Preparation and Characterization of Nanocrystalline Diamonds and Their Applications)

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14 pages, 3085 KiB

Open AccessEditor’s ChoiceArticle

Damage Propagation by Cyclic Loading in Drilled Carbon/Epoxy Plates

by Luis M. P. Durão, João E. Matos, Nuno C. Loureiro, José L. Esteves and Susana C. F. Fernandes

Materials 2023, 16(7), 2688; https://doi.org/10.3390/ma16072688 - 28 Mar 2023

Cited by 6 | Viewed by 1934

Abstract

Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration [...] Read more.

Fiber reinforced composites are widely used in the production of parts for load bearing structures. It is generally recognized that composites can be affected both by monotonic and cyclic loading. For assembly purposes, drilling is needed, but holes can act as stress concentration notches, leading to damage propagation and failure. In this work, a batch of carbon/epoxy plates is drilled by different drill geometries, while thrust force is monitored and the hole’s surrounding region is inspected. Based on radiographic images, the area and other features of the damaged region are computed for damage assessment. Finally, the specimens are subjected to Bearing Fatigue tests. Cyclic loading causes ovality of the holes and the loss of nearly 10% of the bearing net strength. These results can help to establish an association between the damaged region and the material’s fatigue resistance, as larger damage extension and deformation by cyclic stress contribute to the loss of load carrying capacity of parts. Full article

(This article belongs to the Special Issue Damage Analysis for Composite Materials: Methods, Testing and Evaluation)

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16 pages, 4043 KiB

Open AccessEditor’s ChoiceArticle

Effective and Efficient Porous CeO₂ Adsorbent for Acid Orange 7 Adsorption

by Yaohui Xu, Liangjuan Gao, Jinyuan Yang, Qingxiu Yang, Wanxin Peng and Zhao Ding

Materials 2023, 16(7), 2650; https://doi.org/10.3390/ma16072650 - 27 Mar 2023

Cited by 3 | Viewed by 1874

Abstract

A porous CeO₂ was synthesized following the addition of guanidine carbonate to a Ce³⁺ aqueous solution, the subsequent addition of hydrogen peroxide and a final hydrothermal treatment. The optimal experimental parameters for the synthesis of porous CeO₂, including the [...] Read more.

A porous CeO₂ was synthesized following the addition of guanidine carbonate to a Ce³⁺ aqueous solution, the subsequent addition of hydrogen peroxide and a final hydrothermal treatment. The optimal experimental parameters for the synthesis of porous CeO₂, including the amounts of guanidine carbonate and hydrogen peroxide and the hydrothermal conditions, were determined by taking the adsorption efficiency of acid orange 7 (AO7) dye as the evaluation. A template−free hydrothermal strategy could avoid the use of soft or hard templates and the subsequent tedious procedures of eliminating templates, which aligned with the goals of energy conservation and emission reduction. Moreover, both the guanidine carbonate and hydrogen peroxide used in this work were accessible and eco−friendly raw materials. The porous CeO₂ possessed rapid adsorption capacities for AO7 dye. When the initial concentration of AO7 was less than 130 mg/L, removal efficiencies greater than 90.0% were obtained, achieving a maximum value of 97.5% at [AO7] = 100 mg/L and [CeO₂] = 2.0 g/L in the first 10 min of contact. Moreover, the adsorption–desorption equilibrium between the porous CeO₂ adsorbent and the AO7 molecule was basically established within the first 30 min. The saturated adsorption amount of AO7 dye was 90.3 mg/g based on a Langmuir linear fitting of the experimental data. Moreover, the porous CeO₂ could be recycled using a NaOH aqueous solution, and the adsorption efficiency of AO7 dye still remained above 92.5% after five cycles. This study provided an alternative porous adsorbent for the purification of dye wastewater, and a template−free hydrothermal strategy was developed to enable the design of CeO₂−based catalysts or catalyst carriers. Full article

(This article belongs to the Special Issue Recent Progress in Advanced Adsorption Materials)

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18 pages, 20311 KiB

Open AccessEditor’s ChoiceArticle

Study on Dynamic Mechanical Properties of Carbon Fiber-Reinforced Polymer Laminates at Ultra-Low Temperatures

by Wenhao Zhao, Sanchun Lin, Wenfeng Wang, Yifan Yang, Xuan Yan and Heng Yang

Materials 2023, 16(7), 2654; https://doi.org/10.3390/ma16072654 - 27 Mar 2023

Cited by 6 | Viewed by 2288

Abstract

This study uses experimental methods, theoretical research, and numerical prediction to study the dynamic mechanical properties and damage evolution of CFRP laminates at ultra-low temperatures. Based on the Split Hopkinson Pressure Bar (SHPB) device, we set up an ultra-low temperature dynamic experimental platform [...] Read more.

This study uses experimental methods, theoretical research, and numerical prediction to study the dynamic mechanical properties and damage evolution of CFRP laminates at ultra-low temperatures. Based on the Split Hopkinson Pressure Bar (SHPB) device, we set up an ultra-low temperature dynamic experimental platform with a synchronous observation function; the dynamic mechanical properties of laminates were tested, and the damage evolution process was observed. The experimental results are as follows: The compression strength and modulus increase linearly with the increase in strain rate and show a quadratic function trend of increasing and then decreasing with the decrease in temperature. The damage degree of the dynamic bending sample increases obviously with the impact velocity and decreases first and then increases with the decrease in temperature. Based on the low-temperature dynamic damage constitutive, failure criterion, and interlayer interface damage constitutive of the laminates, a numerical model was established to predict the dynamic mechanical properties and damage evolution process of CFRP laminates at ultra-low temperatures, and the finite element analysis (FEA) results are consistent with the experimental results. The results of this paper strongly support the application and safety evaluation of CFRP composites in extreme environments, such as deep space exploration. Full article

(This article belongs to the Special Issue Carbon Fiber Reinforced Polymers (2nd Edition))

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22 pages, 3804 KiB

Open AccessEditor’s ChoiceReview

Progress and Perspective of Glass-Ceramic Solid-State Electrolytes for Lithium Batteries

by Liyang Lin, Wei Guo, Mengjun Li, Juan Qing, Chuang Cai, Ping Yi, Qibo Deng and Wei Chen

Materials 2023, 16(7), 2655; https://doi.org/10.3390/ma16072655 - 27 Mar 2023

Cited by 12 | Viewed by 5320

Abstract

The all-solid-state lithium battery (ASSLIB) is one of the key points of future lithium battery technology development. Because solid-state electrolytes (SSEs) have higher safety performance than liquid electrolytes, and they can promote the application of Li-metal anodes to endow batteries with higher energy [...] Read more.

The all-solid-state lithium battery (ASSLIB) is one of the key points of future lithium battery technology development. Because solid-state electrolytes (SSEs) have higher safety performance than liquid electrolytes, and they can promote the application of Li-metal anodes to endow batteries with higher energy density. Glass-ceramic SSEs with excellent ionic conductivity and mechanical strength are one of the main focuses of SSE research. In this review paper, we discuss recent advances in the synthesis and characterization of glass-ceramic SSEs. Additionally, some discussions on the interface problems commonly found in glass-ceramic SSEs and their solutions are provided. At the end of this review, some drawbacks of glass-ceramic SSEs are summarized, and future development directions are prospected. We hope that this review paper can help the development of glass-ceramic solid-state electrolytes. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Superionic Conductive Glass and Ceramics)

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17 pages, 9819 KiB

Open AccessEditor’s ChoiceArticle

Impact of Titanium Addition on Microstructure, Corrosion Resistance, and Hardness of As-Cast Al+6%Li Alloy

by Marcin Adamiak, Augustine Nana Sekyi Appiah, Anna Woźniak, Paweł M. Nuckowski, Shuhratjon Abdugulomovich Nazarov and Izatullo Navruzovich Ganiev

Materials 2023, 16(7), 2671; https://doi.org/10.3390/ma16072671 - 27 Mar 2023

Cited by 3 | Viewed by 2826

Abstract

Aluminum–lithium alloys have the potential for use in aerospace applications, and improving their physical, mechanical, and operational characteristics through alloying is a pressing task. Lithium, with a density of 0.54 g/cm³, enhances the elastic modulus of aluminum while reducing the weight [...] Read more.

Aluminum–lithium alloys have the potential for use in aerospace applications, and improving their physical, mechanical, and operational characteristics through alloying is a pressing task. Lithium, with a density of 0.54 g/cm³, enhances the elastic modulus of aluminum while reducing the weight of the resulting alloys, making them increasingly attractive. Adding transition metal additives to aluminum alloys enhances their strength, heat resistance, and corrosion resistance, due to their modifying effect and grain refinement. The study aimed to investigate the impact of titanium content on the microstructure, corrosion resistance, and hardness of Al-Li alloys. Four alloys were prepared with varying amounts of titanium at 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%. The results showed that the microstructure of the alloy was modified after adding Ti, resulting in a decrease in average grain size to about 60% with the best refinement at 0.05 wt% Ti content. SEM and EDS analysis revealed an irregular net-shaped interdendritic microstructure with an observed microsegregation of Al₃Li compounds and other trace elements at the grain boundaries. The samples showed casting defects due to the high content of Li in the alloy, which absorbed air during casting, resulting in casting defects such as shrinkage holes. The corrosion resistance test results were low for the samples with casting defects, with the least resistance recorded for a sample containing 0.1 wt% Ti content, with more casting defects. The addition of Ti increased the microhardness of the alloy to an average of 91.8 ± 2.8 HV. Full article

(This article belongs to the Special Issue Advances in Crystallization Kinetics, Structure and Properties of Engineering Materials, Surface-Modified Non-ferrous Alloys)

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38 pages, 29807 KiB

Open AccessEditor’s ChoiceReview

Theory, Method and Practice of Metal Deformation Instability: A Review

by Miaomiao Wan, Fuguo Li, Kenan Yao, Guizeng Song and Xiaoguang Fan

Materials 2023, 16(7), 2667; https://doi.org/10.3390/ma16072667 - 27 Mar 2023

Cited by 10 | Viewed by 5444

Abstract

Deformation instability is a macroscopic and microscopic phenomenon of non-uniformity and unstable deformation of materials under stress loading conditions, and it is affected by the intrinsic characteristics of materials, the structural geometry of materials, stress state and environmental conditions. Whether deformation instability is [...] Read more.

Deformation instability is a macroscopic and microscopic phenomenon of non-uniformity and unstable deformation of materials under stress loading conditions, and it is affected by the intrinsic characteristics of materials, the structural geometry of materials, stress state and environmental conditions. Whether deformation instability is positive and constructive or negative and destructive, it objectively affects daily life at all times and the deformation instability based on metal-bearing analysis in engineering design has always been the focus of attention. Currently, the literature on deformation instability in review papers mainly focuses on the theoretical analysis of deformation instability (instability criteria). However, there are a limited number of papers that comprehensively classify and review the subject from the perspectives of material characteristic response, geometric structure response, analysis method and engineering application. Therefore, this paper aims to provide a comprehensive review of the existing literature on metal deformation instability, covering its fundamental principles, analytical methods, and engineering practices. The phenomenon and definition of deformation instability, the principle and viewpoint of deformation instability, the theoretical analysis, experimental research and simulation calculation of deformation instability, and the engineering application and prospect of deformation instability are described. This will provide a reference for metal bearing analysis and deformation instability design according to material deformation instability, structural deformation instability and localization conditions of deformation instability, etc. From the perspective of practical engineering applications, regarding the key problems in researching deformation instability, using reverse thinking to deduce and analyze the characteristics of deformation instability is the main trend of future research. Full article

(This article belongs to the Special Issue Microstructure, Mechanical Properties, and Deformation Characteristics of Metals and Alloys)

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17 pages, 33833 KiB

Open AccessEditor’s ChoiceArticle

Influence of Accidental Impurities on the Spectroscopic and Luminescent Properties of ZnWO₄ Crystal

by Kirill Subbotin, Anatolii Titov, Victoria Solomatina, Andrew Khomyakov, Ekaterina Pakina, Viktor Yakovlev, Damir Valiev, Marina Zykova, Kristina Kuleshova, Yana Didenko, Denis Lis, Mikhail Grishechkin, Sergei Batygov, Sergei Kuznetsov and Igor Avetissov

Materials 2023, 16(7), 2611; https://doi.org/10.3390/ma16072611 - 25 Mar 2023

Cited by 1 | Viewed by 1824

Abstract

Special techniques for deep purification of ZnO and WO₃ have been developed in this work. A ZnWO₄ single crystal has been grown by the Czochralski method using purified ZnO and WO₃ chemicals, along with the ZnWO₄ crystal-etalon, which has [...] Read more.

Special techniques for deep purification of ZnO and WO₃ have been developed in this work. A ZnWO₄ single crystal has been grown by the Czochralski method using purified ZnO and WO₃ chemicals, along with the ZnWO₄ crystal-etalon, which has been grown at the same conditions using commercially available 5N ZnO and WO₃ chemicals. The actual accidental impurities compositions of both the initial chemicals and the grown crystals have been measured by inductively coupled plasma mass-spectrometry. A complex of comparative spectroscopic studies of the crystals has been performed, including optical absorption spectra, photo-, X-ray-, and cathodoluminescence spectra and decay kinetics, as well as the photoluminescence excitation spectra. The revealed differences in the measured properties of the crystals have been analyzed in terms of influence of the accidental impurities on these properties. Full article

(This article belongs to the Special Issue Crystal Structure, Thermal and Spectral Studies of Coordination Compounds)

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12 pages, 3962 KiB

Open AccessEditor’s ChoiceArticle

Laser Emission Spectroscopy of Graphene Oxide Deposited on 316 Steel and Ti6Al4V Titanium Alloy Suitable for Orthopedics

by Barbara Nasiłowska, Wojciech Skrzeczanowski, Aneta Bombalska and Zdzisław Bogdanowicz

Materials 2023, 16(7), 2574; https://doi.org/10.3390/ma16072574 - 24 Mar 2023

Cited by 8 | Viewed by 1875

Abstract

This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of [...] Read more.

This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the article is to indicate the possibility of using the LIBS spectra for the study of thin layers, including graphene derivatives and other elements. Stratigraphic measurements allowed the detection of differences in the spectra peaks of individual elements, not only in the surface layer itself and in the native material, but also in the intermediate layer connecting the two layers. Due to the clear difference in the outline of the spectrum of graphene oxide and the spectrum of the native material of the samples analyzed, a clear incorporation of carbon atoms into the surface layer was observed. A factor analysis was performed, which confirmed the incorporation of graphene oxide into the surface layer of the native material of the elements examined. Full article

(This article belongs to the Special Issue Material Surfaces and Interactions: Structure, Properties, Processes and Applications)

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17 pages, 4390 KiB

Open AccessEditor’s ChoiceArticle

Long-Term Oxidation of Zirconium Alloy in Simulated Nuclear Reactor Primary Coolant—Experiments and Modeling

by Iva Betova, Martin Bojinov and Vasil Karastoyanov

Materials 2023, 16(7), 2577; https://doi.org/10.3390/ma16072577 - 24 Mar 2023

Cited by 3 | Viewed by 2763

Abstract

Oxidation of Zr-1%Nb fuel cladding alloy in simulated primary coolant of a pressurized water nuclear reactor is followed by in-situ electrochemical impedance spectroscopy. In-depth composition and thickness of the oxide are estimated by ex-situ analytical techniques. A kinetic model of the oxidation process [...] Read more.

Oxidation of Zr-1%Nb fuel cladding alloy in simulated primary coolant of a pressurized water nuclear reactor is followed by in-situ electrochemical impedance spectroscopy. In-depth composition and thickness of the oxide are estimated by ex-situ analytical techniques. A kinetic model of the oxidation process featuring interfacial reactions of metal oxidation and water reduction, as well as electron and ion transport through the oxide governed by diffusion-migration, is parameterized by quantitative comparison to impedance data. The effects of compressive stress on diffusion and ionic space charge on migration of ionic point defects are introduced to rationalize the dependence of transport parameters on thickness (or oxidation time). The influence of ex-situ and in-situ hydrogen charging on kinetic and transport parameters is also studied. Full article

(This article belongs to the Special Issue Corrosion and Mechanical Behavior of Metal Materials)

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15 pages, 16472 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Mechanical and Corrosion Properties via Annealing Treatment on the Hot-Rolled Ti-Zr-Mo Alloy

by Yun Yue, Mingxing Qi, Tianshuo Song, Bohan Chen, Yihao Tang and Chaoqun Xia

Materials 2023, 16(7), 2597; https://doi.org/10.3390/ma16072597 - 24 Mar 2023

Cited by 2 | Viewed by 1600

Abstract

In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that [...] Read more.

In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original β grains of the alloy had all recrystallized to form the β equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance. Full article

(This article belongs to the Section Mechanics of Materials)

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14 pages, 3614 KiB

Open AccessEditor’s ChoiceArticle

Black Liquor and Wood Char-Derived Nitrogen-Doped Carbon Materials for Supercapacitors

by Loreta Tamasauskaite-Tamasiunaite, Jolita Jablonskienė, Dijana Šimkūnaitė, Aleksandrs Volperts, Ance Plavniece, Galina Dobele, Aivars Zhurinsh, Vitalija Jasulaitiene, Gediminas Niaura, Audrius Drabavicius, Mari Juel, Luis Colmenares-Rausseo, Ivar Kruusenberg, Kätlin Kaare and Eugenijus Norkus

Materials 2023, 16(7), 2551; https://doi.org/10.3390/ma16072551 - 23 Mar 2023

Cited by 7 | Viewed by 2286

Abstract

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas [...] Read more.

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m² g⁻¹, respectively, as well as a high volume of mesopores with an average size of 2.9–4.6 nm. The nitrogen content was approximately 3–4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81–142 F g⁻¹ was achieved in a 1 M Na₂SO₄ aqueous solution at a current density of 0.2 A g⁻¹. In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability. Full article

(This article belongs to the Special Issue Nanostructured Materials for Electrochemical Energy Storage)

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28 pages, 18599 KiB

Open AccessEditor’s ChoiceReview

Material-Inherent Noise Sources in Quantum Information Architecture

by HeeBong Yang and Na Young Kim

Materials 2023, 16(7), 2561; https://doi.org/10.3390/ma16072561 - 23 Mar 2023

Cited by 3 | Viewed by 4198

Abstract

NISQ is a representative keyword at present as an acronym for “noisy intermediate-scale quantum”, which identifies the current era of quantum information processing (QIP) technologies. QIP science and technologies aim to accomplish unprecedented performance in computation, communications, simulations, and sensing by exploiting the [...] Read more.

NISQ is a representative keyword at present as an acronym for “noisy intermediate-scale quantum”, which identifies the current era of quantum information processing (QIP) technologies. QIP science and technologies aim to accomplish unprecedented performance in computation, communications, simulations, and sensing by exploiting the infinite capacity of parallelism, coherence, and entanglement as governing quantum mechanical principles. For the last several decades, quantum computing has reached to the technology readiness level 5, where components are integrated to build mid-sized commercial products. While this is a celebrated and triumphant achievement, we are still a great distance away from quantum-superior, fault-tolerant architecture. To reach this goal, we need to harness technologies that recognize undesirable factors to lower fidelity and induce errors from various sources of noise with controllable correction capabilities. This review surveys noisy processes arising from materials upon which several quantum architectures have been constructed, and it summarizes leading research activities in searching for origins of noise and noise reduction methods to build advanced, large-scale quantum technologies in the near future. Full article

(This article belongs to the Special Issue Materials Opportunities and Challenges for Quantum Information Processors)

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14 pages, 5777 KiB

Open AccessEditor’s ChoiceArticle

Lanthanide and Ladder-Structured Polysilsesquioxane Composites for Transparent Color Conversion Layers

by Jaehyun Han, Darya Burak, Valeriia Poliukhova, Albert S. Lee, Hoseong Jang, Seungsang Hwang, Kyung-Youl Baek, Joonsoo Han, Byeong-Kwon Ju and So-Hye Cho

Materials 2023, 16(6), 2537; https://doi.org/10.3390/ma16062537 - 22 Mar 2023

Cited by 1 | Viewed by 2356

Abstract

Ladder-type polysilsesquioxanes (LPSQs) containing phenyl as a high refractive index unit and cyclic epoxy as a curable unit were found to be excellent candidates for a transparent color conversion layer for displays due to being miscible with organic solvents and amenable to transparent [...] Read more.

Ladder-type polysilsesquioxanes (LPSQs) containing phenyl as a high refractive index unit and cyclic epoxy as a curable unit were found to be excellent candidates for a transparent color conversion layer for displays due to being miscible with organic solvents and amenable to transparent film formation. Therefore, the LPSQs were combined with luminescent lanthanide metals, europium Eu(III), and terbium Tb(III), to fabricate transparent films with various emission colors, including red, orange, yellow, and green. The high luminescence and transmittance properties of the LPSQs–lanthanide composite films after thermal curing were attributed to chelating properties of hydroxyl and polyether side chains of LPSQs to lanthanide ions, as well as a light sensitizing effect of phenyl side chains of the LPSQs. Furthermore, Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy and nanoindentation tests indicated that the addition of the nanoparticles to the LPSQs moderately enhanced the epoxy conversion rate and substantially improved the wear resistance, including hardness, adhesion, and insusceptibility to atmospheric corrosion in a saline environment. Thus, the achieved LPGSG–lanthanide hybrid organic–inorganic material could effectively serve as a color conversion layer for displays. Full article

(This article belongs to the Special Issue High-Efficiency Light-Emitting Materials and Devices)

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13 pages, 4966 KiB

Open AccessEditor’s ChoiceArticle

Effect of Solution Treatment Time on Microstructure Evolution and Properties of Mg-3Y-4Nd-2Al Alloy

by Lili Zhao, Sicong Zhao, Yicheng Feng, Lei Wang, Rui Fan, Tao Ma and Liping Wang

Materials 2023, 16(6), 2512; https://doi.org/10.3390/ma16062512 - 22 Mar 2023

Cited by 2 | Viewed by 1976

Abstract

In order to explore the microstructure evolution of an Mg-RE alloy refined by Al during solution treatment, an Mg-3Y-4Nd-2Al alloy was treated at 545 °C for different time periods. Phase evolution of the alloy was investigated. After solution treatment, the Mg-RE eutectic phase [...] Read more.

In order to explore the microstructure evolution of an Mg-RE alloy refined by Al during solution treatment, an Mg-3Y-4Nd-2Al alloy was treated at 545 °C for different time periods. Phase evolution of the alloy was investigated. After solution treatment, the Mg-RE eutectic phase in the Mg-3Y-4Nd-2Al alloy dissolves, the granular Al₂RE phase does not change, the acicular Al₁₁RE₃ phase breaks into the short rod-like Al₂RE phase, and the lamellar Al₂RE phase precipitates in the grains. With the extension of solution time, the precipitated phase of the lamellar Al₂RE increased at first and then decreased, and its orientation relationship with the matrix is

{< 112 >}_{{Al}_{2} RE} {/ / < 2 \bar{1} \bar{1} 0 >}_{Mg}

and

{111}_{{Al}_{2} RE} {/ / {0002}}_{Mg}

. The undissolved granular Al₂RE phase can improve the thermal stability of the alloy grain by pinning the grain boundary, and the grain size did not change after solution treatment. Solution treatment significantly improved the plasticity of the alloy. After 48 h of solution treatment, the elongation increased to 17.5% from 8.5% in the as-cast state. Full article

(This article belongs to the Special Issue Design, Characterization and Applications of Advanced Rare Earth Materials)

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16 pages, 3399 KiB

Open AccessEditor’s ChoiceArticle

PCL and DMSO₂ Composites for Bio-Scaffold Materials

by Jae-Won Jang, Kyung-Eun Min, Cheolhee Kim, Chien Wern and Sung Yi

Materials 2023, 16(6), 2481; https://doi.org/10.3390/ma16062481 - 21 Mar 2023

Cited by 16 | Viewed by 4813

Abstract

Polycaprolactone (PCL) has been one of the most popular biomaterials in tissue engineering due to its relatively low melting temperature, excellent thermal stability, and cost-effectiveness. However, its low cell attraction, low elastic modulus, and long-term degradation time have limited its application in a [...] Read more.

Polycaprolactone (PCL) has been one of the most popular biomaterials in tissue engineering due to its relatively low melting temperature, excellent thermal stability, and cost-effectiveness. However, its low cell attraction, low elastic modulus, and long-term degradation time have limited its application in a wide range of scaffold studies. Dimethyl sulfone (DMSO₂) is a stable and non-hazardous organosulfur compound with low viscosity and high surface tension. PCL and DMSO₂ composites may overcome the limitations of PCL as a biomaterial and tailor the properties of biocomposites. In this study, PCL and DMSO₂ composites were investigated as a new bio-scaffold material to increase hydrophilicity and mechanical properties and tailor degradation properties in vitro. PCL and DMSO₂ were physically mixed with 10, 20, and 30 wt% of DMSO₂ to evaluate thermal, hydrophilicity, mechanical, and degradation properties of the composites. The water contact angle of the composites for hydrophilicity decreased by 15.5% compared to pure PCL. The experimental results showed that the mechanical and degradation properties of PCL and DMSO₂ were better than those of pure PCL, and the properties can be tuned by regulating DMSO2 concentration in the PCL matrix. The elastic modulus of the composite with 30 wt% of DMSO2 showed 532 MPa, and its degradation time was 18 times faster than that of PCL. Full article

(This article belongs to the Section Biomaterials)

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31 pages, 4411 KiB

Open AccessEditor’s ChoiceReview

3D Construction Printing Standing for Sustainability and Circularity: Material-Level Opportunities

by Mariana Fonseca and Ana Mafalda Matos

Materials 2023, 16(6), 2458; https://doi.org/10.3390/ma16062458 - 20 Mar 2023

Cited by 18 | Viewed by 6953

Abstract

Three-dimensional Cementitious materials Printing (3DCP) is a cutting-edge technology for the construction industry. Three-dimensional printed buildings have shown that a well-developed automated technology can foster valuable benefits, such as a freeform architectural design without formworks and reduced human intervention. However, scalability, commercialization and [...] Read more.

Three-dimensional Cementitious materials Printing (3DCP) is a cutting-edge technology for the construction industry. Three-dimensional printed buildings have shown that a well-developed automated technology can foster valuable benefits, such as a freeform architectural design without formworks and reduced human intervention. However, scalability, commercialization and sustainability of the 3DPC technology remain critical issues. The current work presents the ecological fragility, challenges and opportunities inherent in decreasing the 3DCP environmental footprint at a material level (cementitious materials and aggregates). The very demanding performance of printable mixtures, namely in a fresh state, requires high dosages of cement and supplementary cementitious materials (SCM). Besides the heavy carbon footprint of cement production, the standard SCM availability might be an issue, especially in the longer term. One exciting option to decrease the embodied CO₂ of 3DCP is, for example, to incorporate alternative and locally available SCM as partial cement replacements. Those alternative SCM can be wastes or by-products from industries or agriculture, with no added value. Moreover, the partial replacement of natural aggregate can also bring advantages for natural resource preservation. This work has highlighted the enormous potential of 3DCP to contribute to reducing the dependence on Portland cement and to manage the current colossal wastes and by-products with no added value, shifting to a Circular Economy. Though LCA analysis, mixture design revealed a critical parameter in the environmental impact of 3DCP elements or buildings. Even though cement significantly affects the LCA of 3DCP, it is crucial to achieving adequate fresh properties and rheology. From the literature survey, mixtures formulated with alternative SCM (wastes or by-products) are still restricted to rice husk ash, Municipal Solid Waste ashes and recycled powder from construction and demolition wastes. Natural aggregate replacement research has been focused on recycled fine sand, mine tailing, copper tailing, iron tailing, ornamental stone waste, recycled glass, crumb rubber, rubber powder and granules, recycled PET bottles and steel slag. However, flowability loss and mechanical strength decrease are still critical. Research efforts are needed to find low-carbon cement replacements and mix-design optimization, leading to a more sustainable and circular 3DCP while ensuring the final product performance. Full article

(This article belongs to the Special Issue Sustainability and Applications of Materials in Civil Engineering and Building)

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11 pages, 4573 KiB

Open AccessEditor’s ChoiceArticle

Study of Viscoelastic Properties of Graphene Foams Using Dynamic Mechanical Analysis and Coarse-Grained Molecular Dynamics Simulations

by Shenggui Liu, Mindong Lyu, Cheng Yang, Minqiang Jiang and Chao Wang

Materials 2023, 16(6), 2457; https://doi.org/10.3390/ma16062457 - 20 Mar 2023

Cited by 5 | Viewed by 2341

Abstract

As a promising nano-porous material for energy dissipation, the viscoelastic properties of three-dimensional (3D) graphene foams (GrFs) are investigated by combining a dynamic mechanical analysis (DMA) and coarse-grained molecular dynamic (CGMD) simulations. The effects of the different factors, such as the density of [...] Read more.

As a promising nano-porous material for energy dissipation, the viscoelastic properties of three-dimensional (3D) graphene foams (GrFs) are investigated by combining a dynamic mechanical analysis (DMA) and coarse-grained molecular dynamic (CGMD) simulations. The effects of the different factors, such as the density of the GrFs, temperature, loading frequency, oscillatory amplitude, the pre-strain on the storage and loss modulus of the GrFs as well as the micro-mechanical mechanisms are mainly focused upon. Not only the storage modulus but also the loss modulus are found to be independent of the temperature and the frequency. The storage modulus can be weakened slightly by bond-breaking with an increasing loading amplitude. Furthermore, the tensile/compressive pre-strain and density of the GrFs can be used to effectively tune the viscoelastic properties of the GrFs. These results should be helpful not only for understanding the mechanical mechanism of GrFs but also for optimal designs of advanced damping materials. Full article

(This article belongs to the Special Issue New Advances in Characterization of Cellular Materials)

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22 pages, 4966 KiB

Open AccessEditor’s ChoiceArticle

Studies on PVP-Based Hydrogel Polymers as Dressing Materials with Prolonged Anticancer Drug Delivery Function

by Agnieszka Sobczak-Kupiec, Sonia Kudłacik-Kramarczyk, Anna Drabczyk, Karolina Cylka and Bozena Tyliszczak

Materials 2023, 16(6), 2468; https://doi.org/10.3390/ma16062468 - 20 Mar 2023

Cited by 8 | Viewed by 3164

Abstract

Tamoxifen is a well-known active substance with anticancer activity. Currently, many investigations are performed on the development of carriers that provide its effective delivery. Particular attention is directed toward the formation of cyclodextrin–drug complexes to provide prolonged drug delivery. According to our knowledge, [...] Read more.

Tamoxifen is a well-known active substance with anticancer activity. Currently, many investigations are performed on the development of carriers that provide its effective delivery. Particular attention is directed toward the formation of cyclodextrin–drug complexes to provide prolonged drug delivery. According to our knowledge, carriers in the form of polyvinylpyrrolidone (PVP)/gelatin-based hydrogels incorporated with β-cyclodextrin–tamoxifen complexes and additionally modified with nanogold have not been presented in the literature. In this work, two series of these materials have been synthesized—with tamoxifen and with its complex with β-cyclodextrin. The process of obtaining drug carrier systems consisted of several stages. Firstly, the nanogold suspension was obtained. Next, the hydrogels were prepared via photopolymerization. The size, dispersity and optical properties of nanogold as well as the swelling properties of hydrogels, their behavior in simulated physiological liquids and the impact of these liquids on their chemical structure were verified. The release profiles of tamoxifen from composites were also determined. The developed materials showed swelling capacity, stability in tested environments that did not affect their structure, and the ability to release drugs, while the release process was much more effective in acidic conditions than in alkaline ones. This is a benefit considering their use for anticancer drug delivery, due to the fact that near cancer cells, there is an acidic environment. In the case of the composites containing the drug–β-cyclodextrin complex, a prolonged release process was achieved compared to the drug release from materials with unbound tamoxifen. In terms of the properties and the composition, the developed materials show a great application potential as drug carriers, in particular as carriers of anticancer drugs such as tamoxifen. Full article

(This article belongs to the Special Issue Advances in Polymer Nanocomposites: Fabrication, Characterization and Multifunctional Applications)

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12 pages, 3398 KiB

Open AccessEditor’s ChoiceArticle

Selective-Area Growth Mechanism of GaN Microrods on a Plateau Patterned Substrate

by Min-joo Ahn, Woo-seop Jeong, Kyu-yeon Shim, Seongho Kang, Hwayoung Kim, Dae-sik Kim, Junggeun Jhin, Jaekyun Kim and Dongjin Byun

Materials 2023, 16(6), 2462; https://doi.org/10.3390/ma16062462 - 20 Mar 2023

Cited by 2 | Viewed by 3246

Abstract

This study provides experimental evidence regarding the mechanism of gallium nitride (GaN) selective-area growth (SAG) on a polished plateau-patterned sapphire substrate (PP-PSS), on which aluminum nitride (AlN) buffer layers are deposited under the same deposition conditions. The SAG of GaN was only observed [...] Read more.

This study provides experimental evidence regarding the mechanism of gallium nitride (GaN) selective-area growth (SAG) on a polished plateau-patterned sapphire substrate (PP-PSS), on which aluminum nitride (AlN) buffer layers are deposited under the same deposition conditions. The SAG of GaN was only observed on the plateau region of the PP-PSS, irrespective of the number of growth cycles. Indirect samples deposited on the bare c-plane substrate were prepared to determine the difference between the AlN buffer layers in the plateau region and silicon oxide (

{SiO}_{2}

). The AlN buffer layer in the plateau region exhibited a higher surface energy, and its crystal orientation is indicated by AlN [001]. In contrast, regions other than the plateau region did not exhibit crystallinity and presented lower surface energies. The direct analysis results of PP-PSS using transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) are similar to the results of the indirect samples. Therefore, under the same conditions, the GaN SAG of the deposited layer is related to crystallinity, crystal orientation, and surface energy. Full article

(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)

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31 pages, 8201 KiB

Open AccessEditor’s ChoiceReview

Additive Manufacturing Technologies of High Entropy Alloys (HEA): Review and Prospects

by Tomer Ron, Amnon Shirizly and Eli Aghion

Materials 2023, 16(6), 2454; https://doi.org/10.3390/ma16062454 - 19 Mar 2023

Cited by 56 | Viewed by 12962

Abstract

Additive manufacturing (AM) technologies have gained considerable attention in recent years as an innovative method to produce high entropy alloy (HEA) components. The unique and excellent mechanical and environmental properties of HEAs can be used in various demanding applications, such as the aerospace [...] Read more.

Additive manufacturing (AM) technologies have gained considerable attention in recent years as an innovative method to produce high entropy alloy (HEA) components. The unique and excellent mechanical and environmental properties of HEAs can be used in various demanding applications, such as the aerospace and automotive industries. This review paper aims to inspect the status and prospects of research and development related to the production of HEAs by AM technologies. Several AM processes can be used to fabricate HEA components, mainly powder bed fusion (PBF), direct energy deposition (DED), material extrusion (ME), and binder jetting (BJ). PBF technologies, such as selective laser melting (SLM) and electron beam melting (EBM), have been widely used to produce HEA components with good dimensional accuracy and surface finish. DED techniques, such as blown powder deposition (BPD) and wire arc AM (WAAM), that have high deposition rates can be used to produce large, custom-made parts with relatively reduced surface finish quality. BJ and ME techniques can be used to produce green bodies that require subsequent sintering to obtain adequate density. The use of AM to produce HEA components provides the ability to make complex shapes and create composite materials with reinforced particles. However, the microstructure and mechanical properties of AM-produced HEAs can be significantly affected by the processing parameters and post-processing heat treatment, but overall, AM technology appears to be a promising approach for producing advanced HEA components with unique properties. This paper reviews the various technologies and associated aspects of AM for HEAs. The concluding remarks highlight the critical effect of the printing parameters in relation to the complex synthesis mechanism of HEA elements that is required to obtain adequate properties. In addition, the importance of using feedstock material in the form of mix elemental powder or wires rather than pre-alloyed substance is also emphasized in order that HEA components can be produced by AM processes at an affordable cost. Full article

(This article belongs to the Section Metals and Alloys)

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18 pages, 14568 KiB

Open AccessEditor’s ChoiceArticle

Fatigue Behaviors of Joints between Steel Girders with Corrugated Webs and Top RC Slabs under Transverse Bending Moments

by Yun Zhang, Tao Yang, Tingyi Luo, Mingyu Chen and Xiaobin Chen

Materials 2023, 16(6), 2427; https://doi.org/10.3390/ma16062427 - 18 Mar 2023

Cited by 1 | Viewed by 2145

Abstract

Steel–concrete composite box beams are widely used in bridge engineering, which might bear transverse and longitudinal bending moments simultaneously under vehicle loads. To investigate the fatigue performance of joints between the steel girders and the top reinforced concrete (RC) slabs under transverse bending [...] Read more.

Steel–concrete composite box beams are widely used in bridge engineering, which might bear transverse and longitudinal bending moments simultaneously under vehicle loads. To investigate the fatigue performance of joints between the steel girders and the top reinforced concrete (RC) slabs under transverse bending moments, a reduced scale joint between the weathering steel girder with the corrugated steel web (CSW) and the top RC slab was designed and tested under constant amplitude fatigue loads. Test results show that the joint initially cracked in the weld metal connecting the CSW with the bottom girder flange during the fatigue loading process. The initial crack propagated from the longitudinal fold to the adjacent inclined folds after the specimen was subjected to 7.63 × 10⁵ loading cycles and caused the final fatigue failure. Compared with the calculated fatigue lives in the methods recommended by EC3 and AASHTO, the fatigue performance of the details involved in the joint satisfied the demands of fatigue design. Meanwhile, finite element (FE) models of joints with different parameters were established to determine their effect on the stress ranges at the hot spot regions of the joints. Numerical results show that improving the bending radius or the thickness of the CSW helps to reduce the stress ranges in the hot spot regions, which is beneficial to enhance the fatigue resistance of the investigated fatigue details accordingly. Full article

(This article belongs to the Special Issue Experimental Study, Numerical Simulation & Structural Applications of Construction Materials)

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24 pages, 29781 KiB

Open AccessEditor’s ChoiceArticle

Microstructure and Mechanical Properties of Y₄Zr₃O₁₂-Added Fe–13.5Cr–2W Oxide-Dispersion-Strengthened Steels, Containing High Contents of C and N, Prepared by Mechanical Alloying and Two-Step Spark Plasma Sintering

by Yiheng Wu, Qunying Huang, Ligang Zhang, Yong Jiang, Gaofan Zhu and Jingjie Shen

Materials 2023, 16(6), 2433; https://doi.org/10.3390/ma16062433 - 18 Mar 2023

Viewed by 2714

Abstract

Oxide-dispersion-strengthened (ODS) steel is considered as a promising candidate structural material for nuclear applications. In this study, the microstructure and mechanical properties of Y₄Zr₃O₁₂-added Fe–13.5Cr–2W ODS steels, containing high contents of C and N, prepared by mechanical [...] Read more.

Oxide-dispersion-strengthened (ODS) steel is considered as a promising candidate structural material for nuclear applications. In this study, the microstructure and mechanical properties of Y₄Zr₃O₁₂-added Fe–13.5Cr–2W ODS steels, containing high contents of C and N, prepared by mechanical alloying (MA) and two-step spark plasma sintering (SPS), were investigated. The results showed that pure Y₄Zr₃O₁₂ powders, with a grain size of 3.5 nm, were well prepared with NH₃·H₂O addition by the sol-gel method in advance, in order to avoid the formation of some coarse or undesired oxides. W was completely dissolved into the matrix after 48 h of ball milling at 300 rpm, and the main elements were uniformly distributed on the surface of the milled powders. The unexpected face-centered cubic (FCC, γ)/body-centered cubic (BCC, α) dual-phase structure of the sintered specimens, could be explained by the unexpectedly high contents of C and N from the raw powder production process, fast-sintering characteristic of SPS, and inhibitory effect of W on the diffusion of C. The experimental results were approximately consistent with the simulation results from the Thermo Calc software. The temperature combination of 800 °C and 1100 °C during the SPS process, provided a relatively more homogeneous microstructure, while the combination of 750 °C and 1150 °C, provided the highest ultimate tensile strength (UTS), of 1038 MPa, with the highest uniform elongation (UE), of 6.2%. M₂₃C₆, Cr₂O₃, M₂(C,N), and other precipitates, were mainly distributed at grain boundaries, especially at the triple junctions, which led to Cr depletion at grain boundaries. Full article

(This article belongs to the Special Issue Microstructure and Mechanical Properties Analysis of Metallic Structural Materials)

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20 pages, 8659 KiB

Open AccessEditor’s ChoiceArticle

Formation of PLGA–PEDOT: PSS Conductive Scaffolds by Supercritical Foaming

by Antonio Montes, Diego Valor, Yaiza Penabad, Manuel Domínguez, Clara Pereyra and Enrique Martínez de la Ossa

Materials 2023, 16(6), 2441; https://doi.org/10.3390/ma16062441 - 18 Mar 2023

Cited by 4 | Viewed by 2715

Abstract

The usage of conjugated materials for the fabrication of foams intended to be used as therapeutic scaffolds is gaining relevance these days, as they hold certain properties that are not exhibited by other polymer types that have been regularly used until the present. [...] Read more.

The usage of conjugated materials for the fabrication of foams intended to be used as therapeutic scaffolds is gaining relevance these days, as they hold certain properties that are not exhibited by other polymer types that have been regularly used until the present. Hence, this work aims to design a specific supercritical CO₂ foaming process that would allow the production of porous polymeric devices with improved conductive properties, which would better simulate matrix extracellular conditions when used as therapeutic scaffolds (PLGA–PEDOT:PSS) systems. The effects of pressure, temperature, and contact time on the expansion factor, porosity, mechanical properties, and conductivity of the foam have been evaluated. The foams have been characterized by scanning electron and atomic force microscopies, liquid displacement, PBS degradation test, compression, and resistance to conductivity techniques. Values close to 40% porosity were obtained, with a uniform distribution of polymers on the surface and in the interior, expansion factors of up to 10 orders, and a wide range of conductivity values (2.2 × 10⁻⁷ to 1.0 × 10⁻⁵ S/cm) and mechanical properties (0.8 to 13.6 MPa Young’s modulus in compression test). The conductive and porous scaffolds that have been produced by supercritical CO₂ in this study show an interesting potential for tissue engineering and for neural or cardiac tissue regeneration purposes due to the fact that electrical conductivity is a crucial factor for proper cell function and tissue development. Full article

(This article belongs to the Special Issue Conducting Polymers: Structure Characterization, Conductivity, and Application)

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13 pages, 3896 KiB

Open AccessEditor’s ChoiceArticle

Influence of Surface Chemistry of Fiber and Lignocellulosic Materials on Adhesion Properties with Polybutylene Succinate at Nanoscale

by Carlos Marcuello, Brigitte Chabbert, Françoise Berzin, Nicolas B. Bercu, Michael Molinari and Véronique Aguié-Béghin

Materials 2023, 16(6), 2440; https://doi.org/10.3390/ma16062440 - 18 Mar 2023

Cited by 42 | Viewed by 4019

Abstract

The production of bio-based composites with enhanced characteristics constitutes a strategic action to minimize the use of fossil fuel resources. The mechanical performances of these materials are related to the specific properties of their components, as well as to the quality of the [...] Read more.

The production of bio-based composites with enhanced characteristics constitutes a strategic action to minimize the use of fossil fuel resources. The mechanical performances of these materials are related to the specific properties of their components, as well as to the quality of the interface between the matrix and the fibers. In a previous research study, it was shown that the polarity of the matrix played a key role in the mechanisms of fiber breakage during processing, as well as on the final properties of the composite. However, some key questions remained unanswered, and new investigations were necessary to improve the knowledge of the interactions between a lignocellulosic material and a polar matrix. In this work, for the first time, atomic force microscopy based on force spectroscopy measurements was carried out using functionalized tips to characterize the intermolecular interactions at the single molecule level, taking place between poly(butylene succinate) and four different plant fibers. The efficiency of the tip functionalization was checked out by scanning electron microscopy and energy-dispersive X-ray spectroscopy, whereas the fibers chemistry was characterized by Fourier-transform infrared spectroscopy. Larger interactions at the nanoscale level were found between the matrix and hypolignified fibers compared to lignified ones, as in control experiments on single lignocellulosic polymer films. These results could significantly aid in the design of the most appropriate composite composition depending on its final use. Full article

(This article belongs to the Special Issue Advances in the Circularity of Polymeric and Composite Materials)

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21 pages, 6558 KiB

Open AccessEditor’s ChoiceArticle

Influence of Antibacterial Coating and Mechanical and Chemical Treatment on the Surface Properties of PA12 Parts Manufactured with SLS and MJF Techniques in the Context of Medical Applications

by Anna Bazan, Paweł Turek and Andrzej Zakręcki

Materials 2023, 16(6), 2405; https://doi.org/10.3390/ma16062405 - 17 Mar 2023

Cited by 15 | Viewed by 2864

Abstract

Additive manufacturing (AM) is a rapidly growing branch of manufacturing techniques used, among others, in the medical industry. New machines and materials and additional processing methods are improved or developed. Due to the dynamic development of post-processing and its relative novelty, it has [...] Read more.

Additive manufacturing (AM) is a rapidly growing branch of manufacturing techniques used, among others, in the medical industry. New machines and materials and additional processing methods are improved or developed. Due to the dynamic development of post-processing and its relative novelty, it has not yet been widely described in the literature. This study focuses on the surface topography (parameters Sa, Sz, Sdq, Sds, Str, Sdr) of biocompatible polyamide 12 (PA12) samples made by selective laser sintering (SLS) and multi jet fusion (MJF). The surfaces of the samples were modified by commercial methods: four types of smoothing treatments (two mechanical and two chemical), and two antibacterial coatings. The smoothing treatment decreased the values of all analyzed topography parameters. On average, the Sa of the SLS samples was 33% higher than that of the MJF samples. After mechanical treatment, Sa decreased by 42% and after chemical treatment by 80%. The reduction in Sdq and Sdr is reflected in a higher surface gloss. One antibacterial coating did not significantly modify the surface topography. The other coating had a smoothing effect on the surface. The results of the study can help in the development of manufacturing methodologies for parts made of PA12, e.g., in the medical industry. Full article

(This article belongs to the Special Issue Biocompatible Materials Investigated with Optical Methods)

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10 pages, 3270 KiB

Open AccessEditor’s ChoiceArticle

CALPHAD-Based Modelling of the Temperature–Composition–Structure Relationship during Physical Vapor Deposition of Mg-Ca Thin Films

by Philipp Keuter, Moritz to Baben, Shamsa Aliramaji and Jochen M. Schneider

Materials 2023, 16(6), 2417; https://doi.org/10.3390/ma16062417 - 17 Mar 2023

Cited by 4 | Viewed by 1825

Abstract

The temperature-dependent composition and phase formation during the physical vapor deposition (PVD) of Mg-Ca thin films is modeled using a CALPHAD-based approach. Considering the Mg and Ca sublimation fluxes calculated based on the vapor pressure obtained by employing thermochemical equilibrium calculations, the experimentally [...] Read more.

The temperature-dependent composition and phase formation during the physical vapor deposition (PVD) of Mg-Ca thin films is modeled using a CALPHAD-based approach. Considering the Mg and Ca sublimation fluxes calculated based on the vapor pressure obtained by employing thermochemical equilibrium calculations, the experimentally observed synthesis-temperature trends in the thin-film composition and phase formation were reproduced. The model is a significant step towards understanding how synthesis parameters control composition and, therefore, phase formation in the PVD of metals with high vapor pressures. Full article

(This article belongs to the Special Issue Sputter Deposition/Physical Vapor Deposition (PVD) Materials and Processes)

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19 pages, 6699 KiB

Open AccessEditor’s ChoiceArticle

Catalytic Steam-Assisted Pyrolysis of PET for the Upgrading of TPA

by Kuntong Song, Yi Li, Ruiqi Zhang, Nan Wang, Junhong Liu, Wenxia Hou, Qing Zhou and Xingmei Lu

Materials 2023, 16(6), 2362; https://doi.org/10.3390/ma16062362 - 15 Mar 2023

Cited by 3 | Viewed by 2207

Abstract

Compared with conventional pyrolysis, steam-assisted pyrolysis of polyethylene terephthalate (PET) can effectively eliminate char and upgrade terephthalic acid (TPA). However, during steam-assisted pyrolysis of PET, the degree of cracking still varies greatly, and while some of the product is excessively cracked to gas, [...] Read more.

Compared with conventional pyrolysis, steam-assisted pyrolysis of polyethylene terephthalate (PET) can effectively eliminate char and upgrade terephthalic acid (TPA). However, during steam-assisted pyrolysis of PET, the degree of cracking still varies greatly, and while some of the product is excessively cracked to gas, the other part is still insufficiently cracked. In addition, these two types of products seriously affect the yield and purity of TPA. To further enhance the TPA, an attempt was made to reduce these impurities simultaneously by synergistic catalysis among the different components of the metal–acid catalyst. Through a series of experiments, Pt@Hzsm-5 was screened as the optimal catalyst. In the catalytic steam-assisted pyrolysis of PET, the optimum reaction temperature decreased to 400 °C, the calculated yield of TPA increased to 98.23 wt%, and the purity increased to 92.2%. The Pt@Hzsm-5 could be recycled three times with no significant decrease in the obtained yield of TPA. The catalytic mechanism of the Pt@Hzsm-5 was investigated through the analysis of the products and isotope tracing experiments. The Pt catalyzed the hydrogen transfer reaction between the water molecules and PET molecules, which inhibited the excessive cracking of TPA by improving the hydrogen transfer efficiency, reduced the generation of gaseous products, and improved the calculated yield of TPA. In contrast, the Hzsm-5 catalyzed the reaction of monovinyl ester cracking to TPA, effectively reducing the impurities in the solid product, increasing the olefin yield, and improving the purity of TPA. This discovery not only clarifies the synergistic catalytic effect of the Pt@Hzsm-5 in the steam-assisted pyrolysis of the PET reaction but also lays the foundation for further screening of other inexpensive metal–acid catalysts. This is of great significance to realize the industrial application of TPA preparation by PET pyrolysis. Full article

(This article belongs to the Special Issue The Production, Processing and Application of Polymer Composites)

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13 pages, 3927 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Cellulose Nanocrystal Characteristics on Regenerative Silk Composite Fiber Properties

by Hak Jeon Kim and Won Jun Lee

Materials 2023, 16(6), 2323; https://doi.org/10.3390/ma16062323 - 14 Mar 2023

Cited by 7 | Viewed by 2608

Abstract

Cellulose nanocrystals (CNCs), obtained from natural resources, possess great potential as a bioderived reinforcement for natural-fiber-reinforced composites (NFRPs) due to their superior crystallinity and high aspect ratio. To elucidate the specific parameters of CNCs that significantly affect their mechanical performance, various CNCs were [...] Read more.

Cellulose nanocrystals (CNCs), obtained from natural resources, possess great potential as a bioderived reinforcement for natural-fiber-reinforced composites (NFRPs) due to their superior crystallinity and high aspect ratio. To elucidate the specific parameters of CNCs that significantly affect their mechanical performance, various CNCs were investigated to fabricate high-performance nanocomposite fibers together with regenerated silk fibroin (RSF). We confirmed that the high aspect ratio (~9) of the CNCs was the critical factor to increase the tensile strength and stiffness rather than the crystallinity. At a 1 vol% of CNCs, the strength and stiffness reached ~300 MPa and 10.5 GPa, respectively, which was attributed not only to a stable dispersion but also to alignment. This approach has the potential to evaluate the parameters of natural reinforcement and may also be useful in constructing high-performance NFRPs. Full article

(This article belongs to the Special Issue Advances in Nanostructured Materials - 2nd Edition)

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14 pages, 2255 KiB

Open AccessEditor’s ChoiceArticle

Lithium-Ion Glass Gating of HgTe Nanocrystal Film with Designed Light-Matter Coupling

by Stefano Pierini, Claire Abadie, Tung Huu Dang, Adrien Khalili, Huichen Zhang, Mariarosa Cavallo, Yoann Prado, Bruno Gallas, Sandrine Ithurria, Sébastien Sauvage, Jean Francois Dayen, Grégory Vincent and Emmanuel Lhuillier

Materials 2023, 16(6), 2335; https://doi.org/10.3390/ma16062335 - 14 Mar 2023

Cited by 4 | Viewed by 2369

Abstract

Nanocrystals’ (NCs) band gap can be easily tuned over the infrared range, making them appealing for the design of cost-effective sensors. Though their growth has reached a high level of maturity, their doping remains a poorly controlled parameter, raising the need for post-synthesis [...] Read more.

Nanocrystals’ (NCs) band gap can be easily tuned over the infrared range, making them appealing for the design of cost-effective sensors. Though their growth has reached a high level of maturity, their doping remains a poorly controlled parameter, raising the need for post-synthesis tuning strategies. As a result, phototransistor device geometry offers an interesting alternative to photoconductors, allowing carrier density control. Phototransistors based on NCs that target integrated infrared sensing have to (i) be compatible with low-temperature operation, (ii) avoid liquid handling, and (iii) enable large carrier density tuning. These constraints drive the search for innovative gate technologies beyond traditional dielectric or conventional liquid and ion gel electrolytes. Here, we explore lithium-ion glass gating and apply it to channels made of HgTe narrow band gap NCs. We demonstrate that this all-solid gate strategy is compatible with large capacitance up to 2 µF·cm⁻² and can be operated over a broad range of temperatures (130–300 K). Finally, we tackle an issue often faced by NC-based phototransistors:their low absorption; from a metallic grating structure, we combined two resonances and achieved high responsivity (10 A·W⁻¹ or an external quantum efficiency of 500%) over a broadband spectral range. Full article

(This article belongs to the Special Issue Colloidal Quantum Dots for Nanophotonic Devices)

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15 pages, 6146 KiB

Open AccessEditor’s ChoiceArticle

The Calibration Methods of Geometric Parameters of Crystal for Mid-Infrared Acousto-Optic Tunable Filter-Based Imaging Systems Design

by Kai Yu, Qi Guo, Huijie Zhao and Chi Cheng

Materials 2023, 16(6), 2341; https://doi.org/10.3390/ma16062341 - 14 Mar 2023

Cited by 5 | Viewed by 2153

Abstract

AOTF calibration is a complex topic that has various aspects. As far as geometric calibration is concerned, it includes not only processing errors and fixing errors in the optical system, but also the error of geometric parameters of crystal (GPC). GPC is the [...] Read more.

AOTF calibration is a complex topic that has various aspects. As far as geometric calibration is concerned, it includes not only processing errors and fixing errors in the optical system, but also the error of geometric parameters of crystal (GPC). GPC is the preset input in the optical design and optimization of Zemax, which determines the key parameters, including the spatial resolution, the field of view, and aberration. In particular, the compensation of aberration during the optical design requires accurate values of GPC. However, it is currently considered ideal. Therefore, two calibration methods based on the principle of parallel tangent are proposed: (1) the minimum-central wavelength method; (2) the minimum-frequency method. The deviation of the parallel tangent incident angle calibrated by the two methods is 0.03°. As a result, the tuning curve calculated in theory with the calibrated geometric parameters of AOTF is consistent with the tuning curve measured in practice. Full article

(This article belongs to the Special Issue Acousto-Optical Spectral Technologies)

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20 pages, 7909 KiB

Open AccessEditor’s ChoiceArticle

Spherical Attapulgite/Silica Aerogels Fabricated via Different Drying Methods with Excellent Adsorption Performance

by Zhixiang Zhu, Shengyuan Wang, Ya Zhong, Qi You, Jun Gao, Sheng Cui and Xiaodong Shen

Materials 2023, 16(6), 2292; https://doi.org/10.3390/ma16062292 - 13 Mar 2023

Cited by 4 | Viewed by 2809

Abstract

Dye wastewater has caused great harm to the environment, which is an urgent problem to be solved. As typical three-dimensional porous materials, aerogels have attracted great interest in dye wastewater treatment. In this work, spherical attapulgite/silica (ATP/SiO₂) gels were initially prepared [...] Read more.

Dye wastewater has caused great harm to the environment, which is an urgent problem to be solved. As typical three-dimensional porous materials, aerogels have attracted great interest in dye wastewater treatment. In this work, spherical attapulgite/silica (ATP/SiO₂) gels were initially prepared by easily scalable sol-gel dripping methods and then dried to aerogels with three drying techniques, namely, supercritical CO₂ drying (SCD), freeze-drying (FD), and ambient pressure drying (APD). The effect of the drying techniques and heat-treated temperature on the physical characteristic, morphological properties, microstructure, and chemical structure of the spherical ATP/SiO₂ aerogels were investigated. The macroscopic morphology of the spherical ATP/SiO₂ aerogels was homogeneous and integrated without local cracking. The average pore diameter and specific surface area of the spherical ATP/SiO₂ aerogels prepared by the three drying techniques were in the range of 6.8–8.6 nm and 218.5–267.4 m²/g, respectively. The heat treatment temperature had a significant effect on the pore structure and the wetting properties of the aerogels. The 600 °C heat-treated aerogels were subjected to adsorption tests in methylene blue (MB) solution (60 mg/g, 100 mL), which exhibited a great adsorption capacity of 102.50 mg/g. Therefore, the resulting spherical ATP/SiO₂ aerogels possessed multipath preparation and exhibited an efficient adsorption performance, with the potential to be applied as an adsorbent for dye wastewater. Full article

(This article belongs to the Special Issue Advances in Porous Materials: Synthesis, Characterisations and Applications)

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22 pages, 2604 KiB

Open AccessEditor’s ChoiceReview

Recent Advances on PEO-PCL Block and Graft Copolymers as Nanocarriers for Drug Delivery Applications

by Maria Chountoulesi, Dimitrios Selianitis, Stergios Pispas and Natassa Pippa

Materials 2023, 16(6), 2298; https://doi.org/10.3390/ma16062298 - 13 Mar 2023

Cited by 23 | Viewed by 4649

Abstract

Poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) is a family of block (or graft) copolymers with several biomedical applications. These types of copolymers are well-known for their good biocompatibility and biodegradability properties, being ideal for biomedical applications and for the formation of a variety of nanosystems intended [...] Read more.

Poly(ethylene oxide)-poly(ε-caprolactone) (PEO-PCL) is a family of block (or graft) copolymers with several biomedical applications. These types of copolymers are well-known for their good biocompatibility and biodegradability properties, being ideal for biomedical applications and for the formation of a variety of nanosystems intended for controlled drug release. The aim of this review is to present the applications and the properties of different nanocarriers derived from PEO-PCL block and graft copolymers. Micelles, polymeric nanoparticles, drug conjugates, nanocapsules, and hybrid polymer-lipid nanoparticles, such as hybrid liposomes, are the main categories of PEO-PCL based nanocarriers loaded with different active ingredients. The advantages and the limitations in preclinical studies are also discussed in depth. PEO-PCL based nanocarriers could be the next generation of delivery systems with fast clinical translation. Finally, current challenges and future perspectives of the PEO-PCL based nanocarriers are highlighted. Full article

(This article belongs to the Special Issue Drug Delivery: Recent Developments and Future Prospects)

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12 pages, 4971 KiB

Open AccessEditor’s ChoiceArticle

Electrochemical Atomic Force Microscopy Study on the Dynamic Evolution of Lithium Deposition

by Xixiu Shi, Jingru Yang, Wenyang Wang, Zhaoping Liu and Cai Shen

Materials 2023, 16(6), 2278; https://doi.org/10.3390/ma16062278 - 12 Mar 2023

Cited by 5 | Viewed by 3100

Abstract

Lithium metal is one of the most promising anode materials for lithium-ion batteries; however, lithium dendrite growth hinders its large-scale development. So far, the dendrite formation mechanism is unclear. Herein, the dynamic evolution of lithium deposition in etheryl-based and ethylene carbonate (EC)-based electrolytes [...] Read more.

Lithium metal is one of the most promising anode materials for lithium-ion batteries; however, lithium dendrite growth hinders its large-scale development. So far, the dendrite formation mechanism is unclear. Herein, the dynamic evolution of lithium deposition in etheryl-based and ethylene carbonate (EC)-based electrolytes was obtained by combining an in situ electrochemical atomic force microscope (EC-AFM) with an electrochemical workstation. Three growth modes of lithium particles are proposed: preferential, merged, and independent growth. In addition, a lithium deposition schematic is proposed to clearly describe the morphological changes in lithium deposition. This schematic shows the process of lithium deposition, thus providing a theoretical basis for solving the problem of lithium dendrite growth. Full article

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

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11 pages, 3470 KiB

Open AccessEditor’s ChoiceArticle

Bi-Functionalized Transferrin@MoS₂-PEG Nanosheets for Improving Cellular Uptake in HepG2 Cells

by Si Xu, Shanshan Liang, Bing Wang, Jiali Wang, Meng Wang, Lingna Zheng, Hao Fang, Tingfeng Zhang, Yi Bi and Weiyue Feng

Materials 2023, 16(6), 2277; https://doi.org/10.3390/ma16062277 - 12 Mar 2023

Cited by 2 | Viewed by 2152

Abstract

Pre-coating with a protein corona on the surface of nanomaterials (NMs) is an important strategy for reducing non-specific serum protein absorption while maintaining targeting specificity. Here, we present lipoic acid-terminated polyethylene glycol and transferrin bi-functionalized MoS₂ nanosheets (Tf@MoS₂-PEG NSs) as [...] Read more.

Pre-coating with a protein corona on the surface of nanomaterials (NMs) is an important strategy for reducing non-specific serum protein absorption while maintaining targeting specificity. Here, we present lipoic acid-terminated polyethylene glycol and transferrin bi-functionalized MoS₂ nanosheets (Tf@MoS₂-PEG NSs) as a feasible approach to enhance cellular uptake. Tf@MoS₂-PEG NSs can maintain good dispersion stability in cell culture medium and effectively protect MoS₂ NSs from oxidation in ambient aqueous conditions. Competitive adsorption experiments indicate that transferrin was more prone to bind MoS₂ NSs than bovine serum albumin (BSA). It is noteworthy that single HepG2 cell uptake of Tf@MoS₂-PEG presented a heterogeneous distribution pattern, and the cellular uptake amount spanned a broader range (from 0.4 fg to 2.4 fg). Comparatively, the intracellular Mo masses in HepG2 cells treated with BSA@MoS₂-PEG and MoS₂-PEG showed narrower distribution, indicating homogeneous uptake in the single HepG2 cells. Over 5% of HepG2 cells presented uptake of the Tf@MoS₂-PEG over 1.2 fg of Mo, about three-fold that of BSA@MoS₂-PEG (0.4 fg of Mo). Overall, this work suggests that Tf coating enhances the cellular uptake of MoS₂ NSs and is a promising strategy for improving the intracellular uptake efficiency of cancer cells. Full article

(This article belongs to the Special Issue Recent Development of Surface Chemistry of Nanomaterials)

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9 pages, 2450 KiB

Open AccessEditor’s ChoiceCommunication

Effect of Gate Bias Stress on the Electrical Characteristics of Ferroelectric Oxide Thin-Film Transistors with Poly(Vinylidenefluoride-Trifluoroethylene)

by Bon-Seong Gu, Eun-Seo Park, Jin-Hyuk Kwon and Min-Hoi Kim

Materials 2023, 16(6), 2285; https://doi.org/10.3390/ma16062285 - 12 Mar 2023

Viewed by 2663

Abstract

We investigated the effect of gate bias stress (GBS) on the electrical characteristics of ferroelectric oxide thin-film transistors (FeOxTFTs) with poly(vinylidenefluoride-trifluoroethylene). Generally, conventional oxide thin-film transistors (OxTFTs) with dielectric gate insulators exhibit a small negative shift under negative gate bias stress (NBS) and [...] Read more.

We investigated the effect of gate bias stress (GBS) on the electrical characteristics of ferroelectric oxide thin-film transistors (FeOxTFTs) with poly(vinylidenefluoride-trifluoroethylene). Generally, conventional oxide thin-film transistors (OxTFTs) with dielectric gate insulators exhibit a small negative shift under negative gate bias stress (NBS) and a large positive shift under positive gate bias stress (PBS) in transfer characteristic curves. In contrast, the FeOxTFTs show a small positive shift and a large negative shift under NBS and PBS, respectively. It was confirmed that sufficient changes in the electrical characteristics are obtained by 10 min NBS and PBS. The changed electrical characteristics such as threshold voltage shift, memory on- and memory off-current were maintained for more than 168 h after NBS and 24 h after PBS. It is deduced that, since the dipole alignment of the ferroelectric layer is maximized during GBS, these changes in electrical properties are caused by the remnant dipole moments still being retained during the gate sweep. The memory on- and memory off-current are controlled by GBS and the best on/off current ratio at 10⁷ was obtained after NBS. By repeatedly alternating NBS and PBS, the electrical characteristics were reversibly changed. Our results provide the scientific and technological basis for the development of stability and performance optimization of FeOxTFTs. Full article

(This article belongs to the Special Issue Soft Materials and Optical Devices)

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27 pages, 9121 KiB

Open AccessEditor’s ChoiceArticle

Numerical Simulation of Temperature Fields during Laser Welding–Brazing of Al/Ti Plates

by Mária Behúlová and Eva Babalová

Materials 2023, 16(6), 2258; https://doi.org/10.3390/ma16062258 - 11 Mar 2023

Cited by 12 | Viewed by 3156

Abstract

The formation of dissimilar weld joints, including Al/Ti joints, is an area of research supported by the need for weight reduction and corrosion resistance in automotive, aircraft, aeronautic, and other industries. Depending on the cooling rates and chemical composition, rapid solidification of Al/Ti [...] Read more.

The formation of dissimilar weld joints, including Al/Ti joints, is an area of research supported by the need for weight reduction and corrosion resistance in automotive, aircraft, aeronautic, and other industries. Depending on the cooling rates and chemical composition, rapid solidification of Al/Ti alloys during laser welding can lead to the development of different metastable phases and the formation of brittle intermetallic compounds (IMCs). The effort to successfully join aluminum to titanium alloys is associated with demands to minimize the thickness of brittle IMC zones by selecting appropriate welding parameters or applying suitable filler materials. The paper is focused on the numerical simulation of the laser welding–brazing of 2.0 mm thick titanium Grade 2 and EN AW5083 aluminum alloy plates using 5087 aluminum filler wire. The developed simulation model was used to study the impact of laser welding–brazing parameters (laser power, welding speed, and laser beam offset) on the transient temperature fields and weld-pool characteristics. The results of numerical simulations were compared with temperatures measured during the laser welding–brazing of Al/Ti plates using a TruDisk 4002 disk laser, and macrostructural and microstructural analyses, and weld tensile strength measurements, were conducted. The ultimate tensile strength (UTS) of welded–brazed joints increases with an increase in the laser beam offset to the Al side and with an increase in welding speed. The highest UTS values at the level of 220 MPa and 245 MPa were measured for joints produced at a laser power of 1.8 kW along with a welding speed of 30 mm·s⁻¹ and a laser beam offset of 300 μm and 460 μm, respectively. When increasing the laser power to 2 kW, the UTS decreased. The results exhibited that the tensile strength of Al/Ti welded–brazed joints was dependent, regardless of the welding parameters, on the amount of melted Ti Grade 2, which, during rapid solidification, determines the thickness and morphology of the IMC layer. A simple formula was proposed to predict the tensile strength of welded–brazed joints using the computed cross-sectional Ti weld metal area. Full article

(This article belongs to the Section Metals and Alloys)

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15 pages, 1953 KiB

Open AccessEditor’s ChoiceReview

Anomalous Properties of Cyclodextrins and Their Complexes in Aqueous Solutions

by Thorsteinn Loftsson, Hákon Hrafn Sigurdsson and Phatsawee Jansook

Materials 2023, 16(6), 2223; https://doi.org/10.3390/ma16062223 - 10 Mar 2023

Cited by 32 | Viewed by 4427

Abstract

Cyclodextrins (CDs) are cyclic oligosaccharides that emerged as industrial excipients in the early 1970s and are currently found in at least 130 marketed pharmaceutical products, in addition to numerous other consumer products. Although CDs have been the subject of close to 100,000 publications [...] Read more.

Cyclodextrins (CDs) are cyclic oligosaccharides that emerged as industrial excipients in the early 1970s and are currently found in at least 130 marketed pharmaceutical products, in addition to numerous other consumer products. Although CDs have been the subject of close to 100,000 publications since their discovery, and although their structure and properties appear to be trivial, CDs are constantly surprising investigators by their unique physicochemical properties. In aqueous solutions, CDs are solubilizing complexing agents of poorly soluble drugs while they can also act as organic cosolvents like ethanol. CDs and their complexes self-assemble in aqueous solutions to form both nano- and microparticles. The nanoparticles have diameters that are well below the wavelength of visible light; thus, the solutions appear to be clear. However, the nanoparticles can result in erroneous conclusions and misinterpretations of experimental results. CDs can act as penetration enhancers, increasing drug permeation through lipophilic membranes, but they do so without affecting the membrane barrier. This review is an account of some of the unexpected results the authors have encountered during their studies of CDs as pharmaceutical excipients. Full article

(This article belongs to the Special Issue Cyclodextrins: Aged Materials for New Applications)

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13 pages, 3698 KiB

Open AccessEditor’s ChoiceArticle

Raman Characterization of the In-Plane Stress Tensor of Gallium Nitride

by Bowen Han, Mingyuan Sun, Ying Chang, Saisai He, Yuqi Zhao, Chuanyong Qu and Wei Qiu

Materials 2023, 16(6), 2255; https://doi.org/10.3390/ma16062255 - 10 Mar 2023

Cited by 7 | Viewed by 2467

Abstract

Experimental characterization of the in-plane stress tensor is a basic requirement for the development of GaN strain engineering. In this work, a theoretical model of stress characterization for GaN using polarized micro-Raman spectroscopy was developed based on elasticity theory and lattice dynamics. Compared [...] Read more.

Experimental characterization of the in-plane stress tensor is a basic requirement for the development of GaN strain engineering. In this work, a theoretical model of stress characterization for GaN using polarized micro-Raman spectroscopy was developed based on elasticity theory and lattice dynamics. Compared with other works, the presented model can give the quantitative relationship between all components of the in-plane stress tensor and the measured Raman shift. The model was verified by a calibration experiment under step-by-step uniaxial compression. By combining the stress characterization model with the expanding cavity model, the in-plane residual stress component field around Berkovich indentation on the (0001) plane GaN was achieved. The experimental results show that the distributions of the stress components, which significantly differed from the distribution of the Raman shift, were closely related to the GaN crystal structure and exhibited a gradient along each crystal direction. Full article

(This article belongs to the Special Issue Experimental Mechanics of Micro-Nano Scale Spectroscopy)

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14 pages, 3306 KiB

Open AccessEditor’s ChoiceArticle

Deashed Wheat-Straw Biochar as a Potential Superabsorbent for Pesticides

by Irmina Ćwieląg-Piasecka, Elżbieta Jamroz, Agnieszka Medyńska-Juraszek, Magdalena Bednik, Bogna Kosyk and Nora Polláková

Materials 2023, 16(6), 2185; https://doi.org/10.3390/ma16062185 - 9 Mar 2023

Cited by 18 | Viewed by 5185

Abstract

Biochar activation methods have attracted extensive attention due to their great role in improving sorptive properties of carbon-based materials. As a result, chemically modified biochars gained application potential in the purification of soil and water from xenobiotics. This paper describes changes in selected [...] Read more.

Biochar activation methods have attracted extensive attention due to their great role in improving sorptive properties of carbon-based materials. As a result, chemically modified biochars gained application potential in the purification of soil and water from xenobiotics. This paper describes changes in selected physicochemical properties of high-temperature wheat-straw biochar (BC) upon its deashing. On the pristine and chemically activated biochar (BCd) retention of five pesticides of endocrine disrupting activity (carbaryl, carbofuran, 2,4-D, MCPA and metolachlor) was studied. Deashing resulted in increased sorbent aromaticity and abundance in surface hydroxyl groups. BCd exhibited more developed meso- and microporosity and nearly triple the surface area of BC. Hydrophobic pesticides (metolachlor and carbamates) displayed comparably high (88–98%) and irreversible adsorption on both BCs, due to the pore filling, whereas the hydrophilic and ionic phenoxyacetic acids were weakly and reversibly sorbed on BC (7.3 and 39% of 2,4-D and MCPA dose introduced). Their removal from solution and hence retention on the deashed biochar was nearly total, due to the increased sorbent surface area and interactions of the agrochemicals with unclogged OH groups. The modified biochar has the potential to serve as a superabsorbent, immobilizing organic pollutant of diverse hydrophobicity from water and soil solution. Full article

(This article belongs to the Special Issue Biochar and Carbon-Based Materials: Properties and Applications)

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14 pages, 3476 KiB

Open AccessEditor’s ChoiceArticle

Bismuth−Antimony Alloy Embedded in Carbon Matrix for Ultra-Stable Sodium Storage

by Wensheng Ma, Bin Yu, Fuquan Tan, Hui Gao and Zhonghua Zhang

Materials 2023, 16(6), 2189; https://doi.org/10.3390/ma16062189 - 9 Mar 2023

Cited by 5 | Viewed by 2627

Abstract

Alloy-type anodes are the most promising candidates for sodium-ion batteries (SIBs) due to their impressive Na storage capacity and suitable voltage platform. However, the implementation of alloy-type anodes is significantly hindered by their huge volume expansion during the alloying/dealloying processes, which leads to [...] Read more.

Alloy-type anodes are the most promising candidates for sodium-ion batteries (SIBs) due to their impressive Na storage capacity and suitable voltage platform. However, the implementation of alloy-type anodes is significantly hindered by their huge volume expansion during the alloying/dealloying processes, which leads to their pulverization and detachment from current collectors for active materials and the unsatisfactory cycling performance. In this work, bimetallic Bi−Sb solid solutions in a porous carbon matrix are synthesized by a pyrolysis method as anode material for SIBs. Adjustable alloy composition, the introduction of porous carbon matrix, and nanosized bimetallic particles effectively suppress the volume change during cycling and accelerate the electrons/ions transport kinetics. The optimized Bi₁Sb₁@C electrode exhibits an excellent electrochemical performance with an ultralong cycle life (167.2 mAh g⁻¹ at 1 A g⁻¹ over 8000 cycles). In situ X-ray diffraction investigation is conducted to reveal the reversible and synchronous sodium storage pathway of the Bi₁Sb₁@C electrode: (Bi,Sb) Na(Bi,Sb) Na₃(Bi,Sb). Furthermore, online electrochemical mass spectrometry unveils the evolution of gas products of the Bi₁Sb₁@C electrode during the cell operation. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Batteries)

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26 pages, 10631 KiB

Open AccessEditor’s ChoiceArticle

Production of Nano Hydroxyapatite and Mg-Whitlockite from Biowaste-Derived products via Continuous Flow Hydrothermal Synthesis: A Step towards Circular Economy

by Farah Nigar, Amy-Louise Johnston, Jacob Smith, William Oakley, Md Towhidul Islam, Reda Felfel, David Grant, Edward Lester and Ifty Ahmed

Materials 2023, 16(6), 2138; https://doi.org/10.3390/ma16062138 - 7 Mar 2023

Cited by 6 | Viewed by 3811

Abstract

Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH₃COOH as dissolution [...] Read more.

Biowastes from agriculture, sewage, household wastes, and industries comprise promising resources to produce biomaterials while reducing adverse environmental effects. This study focused on utilising waste-derived materials (i.e., eggshells as a calcium source, struvite as a phosphate source, and CH₃COOH as dissolution media) to produce value-added products (i.e., calcium phosphates (CaPs) derived from biomaterials) using a continuous flow hydrothermal synthesis route. The prepared materials were characterised via XRD, FEG-SEM, EDX, FTIR, and TEM analysis. Magnesium whitlockite (Mg-WH) and hydroxyapatite (HA) were produced by single-phase or biphasic CaPs by reacting struvite with either calcium nitrate tetrahydrate or an eggshell solution at 200 °C and 350 °C. Rhombohedral-shaped Mg-WH (23–720 nm) along with tube (50–290 nm diameter, 20–71 nm thickness) and/or ellipsoidal morphologies of HA (273–522 nm width) were observed at 350 °C using HNO₃ or CH₃COOH to prepare the eggshell and struvite solutions, and NH₄OH was used as the pH buffer. The Ca/P (atomic%) ratios obtained ranged between 1.3 and 1.7, indicating the formation of Mg-WH and HA. This study showed that eggshells and struvite usage, along with CH₃COOH, are promising resources as potential sustainable precursors and dissolution media, respectively, to produce CaPs with varying morphologies. Full article

(This article belongs to the Special Issue Feature Papers in the Section Advanced and Functional Ceramics and Glasses)

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11 pages, 3967 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Hydrogel Composites Using a Sustainable Approach for In Situ Silver Nanoparticles Formation

by Laura Chronopoulou, Roya Binaymotlagh, Sara Cerra, Farid Hajareh Haghighi, Enea Gino Di Domenico, Francesca Sivori, Ilaria Fratoddi, Silvano Mignardi and Cleofe Palocci

Materials 2023, 16(6), 2134; https://doi.org/10.3390/ma16062134 - 7 Mar 2023

Cited by 11 | Viewed by 2515

Abstract

The recognized antibacterial properties of silver nanoparticles (AgNPs) characterize them as attractive nanomaterials for developing new bioactive materials less prone to the development of antibiotic resistance. In this work, we developed new composites based on self-assembling Fmoc-Phe3 peptide hydrogels impregnated with in situ [...] Read more.

The recognized antibacterial properties of silver nanoparticles (AgNPs) characterize them as attractive nanomaterials for developing new bioactive materials less prone to the development of antibiotic resistance. In this work, we developed new composites based on self-assembling Fmoc-Phe3 peptide hydrogels impregnated with in situ prepared AgNPs. Different methodologies, from traditional to innovative and eco-sustainable, were compared. The obtained composites were characterized from a hydrodynamic, structural, and morphological point of view, using different techniques such as DLS, SEM, and rheological measurements to evaluate how the choice of the reducing agent determines the characteristics of AgNPs and how their presence within the hydrogel affects their structure and properties. Moreover, the antibacterial properties of these composites were tested against S. aureus, a major human pathogen responsible for a wide range of clinical infections. Results demonstrated that the hydrogel composites containing AgNPs (hgel@AgNPs) could represent promising biomaterials for treating S. aureus-related infections. Full article

(This article belongs to the Special Issue New Advances in Nanomaterials)

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16 pages, 22247 KiB

Open AccessEditor’s ChoiceArticle

Effect of Gd³⁺, La³⁺, Lu³⁺ Co-Doping on the Morphology and Luminescent Properties of NaYF₄:Sm³⁺ Phosphors

by Viktor G. Nosov, Anna A. Betina, Tatyana S. Bulatova, Polina B. Guseva, Ilya E. Kolesnikov, Sergey N. Orlov, Maxim S. Panov, Mikhail N. Ryazantsev, Nikita A. Bogachev, Mikhail Yu Skripkin and Andrey S. Mereshchenko

Materials 2023, 16(6), 2157; https://doi.org/10.3390/ma16062157 - 7 Mar 2023

Cited by 5 | Viewed by 2946

Abstract

The series of luminescent NaYF₄:Sm³⁺ nano- and microcrystalline materials co-doped by La³⁺, Gd³⁺, and Lu³⁺ ions were synthesized by hydrothermal method using rare earth chlorides as the precursors and citric acid as a stabilizing agent. [...] Read more.

The series of luminescent NaYF₄:Sm³⁺ nano- and microcrystalline materials co-doped by La³⁺, Gd³⁺, and Lu³⁺ ions were synthesized by hydrothermal method using rare earth chlorides as the precursors and citric acid as a stabilizing agent. The phase composition of synthesized compounds was studied by PXRD. All synthesized materials except ones with high La³⁺ content (where LaF₃ is formed) have a β-NaYF₄ crystalline phase. SEM images demonstrate that all particles have shape of hexagonal prisms. The type and content of doping REE significantly effect on the particle size. Upon 400 nm excitation, phosphors exhibit distinct emission peaks in visible part of the spectrum attributed to ⁴G_5/2→⁶H_J transitions (J = 5/2–11/2) of Sm³⁺ ion. Increasing the samarium (III) content results in concentration quenching by dipole–dipole interactions, the optimum Sm³⁺concentration is found to be of 2%. Co-doping by non-luminescent La³⁺, Gd³⁺ and Lu³⁺ ions leads to an increase in emission intensity. This effect was explained from the Sm³⁺ local symmetry point of view. Full article

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

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14 pages, 4881 KiB

Open AccessEditor’s ChoiceArticle

Inductive Determination of Rate-Reaction Equation Parameters for Dislocation Structure Formation Using Artificial Neural Network

by Yoshitaka Umeno, Emi Kawai, Atsushi Kubo, Hiroyuki Shima and Takashi Sumigawa

Materials 2023, 16(5), 2108; https://doi.org/10.3390/ma16052108 - 5 Mar 2023

Cited by 6 | Viewed by 2003

Abstract

The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the [...] Read more.

The reaction–diffusion equation approach, which solves differential equations of the development of density distributions of mobile and immobile dislocations under mutual interactions, is a method widely used to model the dislocation structure formation. A challenge in the approach is the difficulty in the determination of appropriate parameters in the governing equations because deductive (bottom-up) determination for such a phenomenological model is problematic. To circumvent this problem, we propose an inductive approach utilizing the machine-learning method to search a parameter set that produces simulation results consistent with experiments. Using a thin film model, we performed numerical simulations based on the reaction–diffusion equations for various sets of input parameters to obtain dislocation patterns. The resulting patterns are represented by the following two parameters; the number of dislocation walls (

p_{2}

), and the average width of the walls (

p_{3}

). Then, we constructed an artificial neural network (ANN) model to map between the input parameters and the output dislocation patterns. The constructed ANN model was found to be able to predict dislocation patterns; i.e., average errors in

p_{2}

and

p_{3}

for test data having 10% deviation from the training data were within 7% of the average magnitude of

p_{2}

and

p_{3}

. The proposed scheme enables us to find appropriate constitutive laws that lead to reasonable simulation results, once realistic observations of the phenomenon in question are provided. This approach provides a new scheme to bridge models for different length scales in the hierarchical multiscale simulation framework. Full article

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

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