Journal Description
Crystals
Crystals
is an international, peer-reviewed, open access journal on Crystallography published monthly online by MDPI. The Professional Committee of Key Materials and Technology for Electronic Components (PC-KMTEC) is affiliated with Crystals and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Crystallography) / CiteScore - Q2 (Condensed Matter Physics)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 10.6 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.7 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
High-Performance Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol over Pt Nanoparticles Supported on Co-Al LDH Nanosheets
Crystals 2024, 14(3), 284; https://doi.org/10.3390/cryst14030284 (registering DOI) - 19 Mar 2024
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In this study, a Pt@Co-Al LDH hybrid structure was fabricated by assembling the metal precursor PtCl62− with the exfoliated LDH nanosheets followed by in situ reduction by NaBH4. The morphology, composition and microstructure of the hybrid were characterized by
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In this study, a Pt@Co-Al LDH hybrid structure was fabricated by assembling the metal precursor PtCl62− with the exfoliated LDH nanosheets followed by in situ reduction by NaBH4. The morphology, composition and microstructure of the hybrid were characterized by FESEM, HRTEM, XRD, XPS and BET techniques. Pt nanoparticles (NPs) with an average particle size of 3.1 nm were successfully and uniformly loaded on the surface of LDH nanosheets. The catalytic activity of the Pt@Co-Al LDH hybrid was tested for the reduction of 4-nitrophenol, which is one of the most frequent pollutants in wastewater effluent from the pharmaceutical and textile industries. The hybrid displays superior catalytic activity and stability in the reduction of 4-NP under environmental conditions with NaBH4 as a reducing agent. The hybrid can be recovered in a simple way and still shows high catalytic activity after five reuses.
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Open AccessArticle
Crystallography and Interface Structures in As-Arc Melted and Laser Surface-Remelted Aluminum–Silicon Alloys with and without Strontium Addition
by
Bibhu P. Sahu, Mohsen T. Andani, Arkajit Ghosh, Jian Wang and Amit Misra
Crystals 2024, 14(3), 283; https://doi.org/10.3390/cryst14030283 - 18 Mar 2024
Abstract
The crystallography of the eutectic Al-Si microstructure in both unmodified and Sr (0.2 wt.%)-modified hypereutectic Al-20 wt.% Si alloys, processed via arc-melting and laser surface remelting, has been comprehensively characterized using transmission electron microscopy and electron diffraction. Although, under as-cast conditions, specific orientations
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The crystallography of the eutectic Al-Si microstructure in both unmodified and Sr (0.2 wt.%)-modified hypereutectic Al-20 wt.% Si alloys, processed via arc-melting and laser surface remelting, has been comprehensively characterized using transmission electron microscopy and electron diffraction. Although, under as-cast conditions, specific orientations between different planes of Al and Si, satisfying defined orientation relationships (ORs), have been investigated within the flake morphology, the rapid solidification induced by laser surface remelting results in a notable transformation from a flake morphology to nanocrystalline Si fibers dispersed in an Al matrix. Consequently, this transformation results in a mis-orientation of the interface between the eutectic Al and Si phases, preventing the formation of orientation relationships, thus promoting the formation of faceted interfaces exhibiting substantial lattice disregistry.
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(This article belongs to the Section Crystalline Metals and Alloys)
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Open AccessCorrection
Correction: Pang et al. Burning Rate Prediction of Solid Rocket Propellant (SRP) with High-Energy Materials Genome (HEMG). Crystals 2023, 13, 237
by
Weiqiang Pang, Victor Abrukov, Darya Anufrieva and Dongping Chen
Crystals 2024, 14(3), 282; https://doi.org/10.3390/cryst14030282 - 18 Mar 2024
Abstract
There was an error in the original publication [...]
Full article
(This article belongs to the Special Issue Advanced Energetic Materials: Testing and Modeling)
Open AccessArticle
Synthesis and Crystallographic Characterization of Heteroleptic Ir(III) Complexes Containing the N-oxide Functional Group and Crystallographic Characterization of Ir(III) N-oxide Precursors
by
Emily E. Stumbo, Emarald K. Hodge, Matthew Williams, Diana A. Thornton, Colin D. McMillen and Jared A. Pienkos
Crystals 2024, 14(3), 281; https://doi.org/10.3390/cryst14030281 - 16 Mar 2024
Abstract
The N-oxide functional group has been exploited for synthetic strategies and drug design, and it has been utilized in imaging agents. Herein, we present rare examples of neutral heteroleptic cyclometallated Ir(III) compounds that contain an uncoordinated N-oxide functional group. These species,
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The N-oxide functional group has been exploited for synthetic strategies and drug design, and it has been utilized in imaging agents. Herein, we present rare examples of neutral heteroleptic cyclometallated Ir(III) compounds that contain an uncoordinated N-oxide functional group. These species, along with others described within, were verified by NMR, EA, HRMS, and single-crystal X-ray analysis. N-oxide-containing Ir(III) species were prepared selectively in high yields > 66% from chloro-bridged Ir(III) dimers with Acipimox, a picolinate-type ligand containing the N-oxide functional group. Non-N-oxide analogs were synthesized in a similar fashion (yields > 77%). Electrochemical comparison (cyclic voltammetry) indicates that the presence of an N-oxide functional group anodically shifts the reduction potential, suggesting that the N-oxide is acting as an electron-withdrawing group in these species. Crystallographic studies were pursued to examine the coordination behavior of these N-oxides compared to their non-oxidized congeners. The Ir(III) complexes with Acipimox indeed leave the N-oxide uncoordinated and exposed on the complexes. The uncoordinated N-oxide group is influential in directing the packing structures of these complexes directly through C-H···O and O···π interactions at the N-oxide. The crystallographic characterization of cationic Ir(III) compounds with uncoordinated nitrogen atoms is also presented. The C-H···N interactions between these complexes form a variety of dimers, finite chains, and continuous chains. Future work will focus on functionalizing the cationic Ir(III) species into their corresponding N-oxide derivatives and rigorously characterizing how the N-oxide functional group impacts the optical properties of transition metal compounds in both cationic and neutral complexes.
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(This article belongs to the Section Macromolecular Crystals)
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Open AccessCommunication
Machinability of MoS2 after Oxygen Plasma Treatment under Mechanical Scanning Probe Lithography
by
Yang He, Xing Su and Kuo Hai
Crystals 2024, 14(3), 280; https://doi.org/10.3390/cryst14030280 - 15 Mar 2024
Abstract
The surface of molybdenum disulfide (MoS2) underwent oxygen plasma treatment to enhance its machinability and mitigate the tearing effects commonly associated with mechanical forces on 2D materials. This treatment led to the oxidation of the atoms on the top 1–3 layers
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The surface of molybdenum disulfide (MoS2) underwent oxygen plasma treatment to enhance its machinability and mitigate the tearing effects commonly associated with mechanical forces on 2D materials. This treatment led to the oxidation of the atoms on the top 1–3 layers of MoS2, resulting in the formation of MoO3 on the surface. During mechanical scanning probe lithography (m-SPL), only the surface oxide layer was uniformly removed, with material accumulation occurring predominantly on one side of the machined area. The resolution of the machining process was significantly enhanced via dynamic lithography while maintaining atomic-level smoothness in the machined area. Importantly, these techniques only removed the surface oxide layer, preserving the integrity of the underlying MoS2 surface, which was pivotal in avoiding damage to the original material structure. This study provided valuable insights and practical guidance for the nanofabrication of transition metal dichalcogenides (TMDCs) nanodevices, demonstrating a method to finely tune the machining of these materials.
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(This article belongs to the Section Inorganic Crystalline Materials)
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Open AccessArticle
Structural Evolution and Mechanical Behavior of Ytterbia Doped Hafnia Biphasic Ceramics under Annealing at 1500 °C
by
Yang Wu, Hao Lan, Xiaoming Sun, Zihao Hu, Yonghui Sun, Huifeng Zhang, Chuanbing Huang and Weigang Zhang
Crystals 2024, 14(3), 279; https://doi.org/10.3390/cryst14030279 - 15 Mar 2024
Abstract
HfO2 has become a promising thermal barrier coating material due to its similarity in structure and chemical properties with ZrO2 and its higher phase structure transition temperature. However, the fracture toughness of HfO2 is not ideal, greatly limiting its application.
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HfO2 has become a promising thermal barrier coating material due to its similarity in structure and chemical properties with ZrO2 and its higher phase structure transition temperature. However, the fracture toughness of HfO2 is not ideal, greatly limiting its application. In this report, we find a special sandwich structure of ceramics, comprising a cubic (C) phase /monoclinic (M) phase/cubic (C) phase. The microstructural evolution and mechanical properties of these ceramics were investigated under annealing at 1500 °C. The results indicate that, with an increase in annealing duration, there was a gradual augmentation in the proportion of the monoclinic (M) phase and the fracture toughness increased from 2.18 MPa·m0.5 to 2.83 MPa·m0.5 after 48 h of annealing, which is higher than many potential TBC materials. The residual compressive stress present in the M phases during the progression of crack propagation served to facilitate the bridging and deflection of cracks. As such, this process led to the alleviation of stress concentration at the crack tip, ultimately enhancing the toughening effect.
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(This article belongs to the Special Issue Ceramics: Processes, Microstructures, and Properties)
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CaH2-Assisted Molten Salt Synthesis of Zinc-Rich Intermetallic Compounds of RhZn13 and Pt3Zn10 for Catalytic Selective Hydrogenation Application
by
Yasukazu Kobayashi, Koharu Yamamoto and Ryo Shoji
Crystals 2024, 14(3), 278; https://doi.org/10.3390/cryst14030278 - 15 Mar 2024
Abstract
Zinc-included intermetallic compound catalysts of RhZn, PtZn, and PdZn with a molar ration of Zn/metal = 1/1, which are generally prepared using a hydrogen reduction approach, are known to show excellent catalytic performance in some selective hydrogenations of organic compounds. In this study,
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Zinc-included intermetallic compound catalysts of RhZn, PtZn, and PdZn with a molar ration of Zn/metal = 1/1, which are generally prepared using a hydrogen reduction approach, are known to show excellent catalytic performance in some selective hydrogenations of organic compounds. In this study, in order to reduce the incorporated mounts of the expensive noble metals, we attempted to prepare zinc-rich intermetallic compounds via a CaH2-assisted molten salt synthesis method with a stronger reduction capacity than the common hydrogen reduction method. X-ray diffraction results indicated the formation of RhZn13 and Pt3Zn10 in the samples prepared by the reduction of ZnO-supported metal precursors. In a hydrogenation reaction of p-nitrophenol to p-aminophenol, the ZnO-supported RhZn13 and Pt3Zn10 catalysts showed a higher selectivity than the RhZn/ZnO and PtZn/ZnO catalysts with the almost similar conversions. Thus, it was demonstrated that the zinc-rich intermetallic compounds of RhZn13 and Pt3Zn10 could be superior selective hydrogenation catalysts compared to the conventional intermetallic compound catalysts of RhZn and PtZn.
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(This article belongs to the Special Issue Advanced Crystalline Materials, Mechanical Properties and Innovative Production Systems (2nd Edition))
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Open AccessCorrection
Correction: Lopresti, M. et al. The Crystal Structure of Calcium Sebacate by X-ray Powder Diffraction Data. Crystals 2023, 13, 261
by
Mattia Lopresti, Marco Milanesio and Luca Palin
Crystals 2024, 14(3), 277; https://doi.org/10.3390/cryst14030277 - 15 Mar 2024
Abstract
In the original publication [...]
Full article
(This article belongs to the Special Issue Young Crystallographers Across Europe)
Open AccessArticle
Comparative Analysis of Room Temperature Structures Determined by Macromolecular and Serial Crystallography
by
Ki Hyun Nam
Crystals 2024, 14(3), 276; https://doi.org/10.3390/cryst14030276 - 14 Mar 2024
Abstract
Temperature directly influences the function and structure of proteins. Crystal structures determined at room temperature offer more biologically relevant structural information regarding flexibility, rigidity, and thermal motion than those determined by conventional cryocrystallography. Crystal structures can be determined at room temperature using conventional
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Temperature directly influences the function and structure of proteins. Crystal structures determined at room temperature offer more biologically relevant structural information regarding flexibility, rigidity, and thermal motion than those determined by conventional cryocrystallography. Crystal structures can be determined at room temperature using conventional macromolecular crystallography (MX) or serial crystallography (SX) techniques. Among these, MX may theoretically be affected by radiation damage or X-ray heating, potentially resulting in differences between the room temperature structures determined by MX and SX, but this has not been fully elucidated. In this study, the room temperature structure of xylanase GH11 from Thermoanaerobacterium saccharolyticum was determined by MX (RT-TsaGH11-MX). The RT-TsaGH11-MX exhibited both the open and closed conformations of the substrate-binding cleft within the β-sandwich fold. The RT-TsaGH11-MX showed distinct structural changes and molecular flexibility when compared with the RT-TsaGH11 determined via serial synchrotron crystallography. The notable molecular conformation and flexibility of the RT-TsaGH11-MX may be induced by radiation damage and X-ray heating. These findings will broaden our understanding of the potential limitations of room temperature structures determined by MX.
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(This article belongs to the Section Macromolecular Crystals)
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Open AccessReview
Decoding Material Structures with Scanning Electron Diffraction Techniques
by
Sangmoon Yoon
Crystals 2024, 14(3), 275; https://doi.org/10.3390/cryst14030275 - 14 Mar 2024
Abstract
Recent advancements in electron detectors and computing power have revolutionized the rapid recording of millions of 2D diffraction patterns across a grid of probe positions, known as four-dimensional scanning transmission electron microscopy (4D-STEM). These datasets serve as the foundation for innovative STEM imaging
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Recent advancements in electron detectors and computing power have revolutionized the rapid recording of millions of 2D diffraction patterns across a grid of probe positions, known as four-dimensional scanning transmission electron microscopy (4D-STEM). These datasets serve as the foundation for innovative STEM imaging techniques like integrated center of mass (iCOM) and symmetry STEM (S-STEM). This paper delves into the application of 4D-STEM datasets for diffraction analysis. We therefore use the term scanning electron diffraction (SED) instead of 4D-STEM in this review. We comprehensively explore groundbreaking diffraction methods based on SED, structured into two main segments: (i) utilizing an atomic-scale electron probe and (ii) employing a nanoscale electron probe. Achieving an atomic-scale electron probe necessitates a significant convergence angle (α > 30 mrad), leading to interference between direct and diffracted beams, distinguishing it from its nanoscale counterpart. Additionally, integrating machine learning approaches with SED experiments holds promise in various directions, as discussed in this review. Our aim is to equip materials scientists with valuable insights for characterizing atomic structures using cutting-edge SED techniques.
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(This article belongs to the Special Issue Application of X-ray and Electron to Crystal Structure Characterization)
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The Effect of Annealing Treatment on the Microstructure and Texture of a Cold-Rolled TiNiFe Shape Memory Alloy Tube
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Jianxian Wen, Xiaoyun Song, Yanfeng Li, Shuwei Liu, Yang Yu, Wenjun Ye and Songxiao Hui
Crystals 2024, 14(3), 274; https://doi.org/10.3390/cryst14030274 - 14 Mar 2024
Abstract
The effect of annealing treatment on the microstructure and texture of a Ti50Ni47Fe3 shape memory alloy tube was studied. The results show that the recrystallization process of a cold-rolled Ti50Ni47Fe3 alloy tube occurs
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The effect of annealing treatment on the microstructure and texture of a Ti50Ni47Fe3 shape memory alloy tube was studied. The results show that the recrystallization process of a cold-rolled Ti50Ni47Fe3 alloy tube occurs at 600 °C. The microstructure changes from long striped grains to equiaxed recrystallized grains. The main texture of the alloy tube is the fiber texture <111> parallel to RD. With the increase in the annealing temperature, the crystal orientation of the alloy gradually turned to (111)<112>, and a series of secondary textures were distributed along the γ orientation line when the alloy was annealed at a lower temperature (450~600 °C). When the alloy was annealed at 650 °C, the growth of recrystallized grains made the grain orientation change, which led to the weakening of the γ-fiber texture and the formation of recrystallization textures.
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(This article belongs to the Section Crystalline Metals and Alloys)
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Multi-Source Ferrous Metallurgical Dust and Sludge Recycling: Present Situation and Future Prospects
by
Jiansong Zhang, Yuzhu Zhang, Yue Long, Peipei Du, Tielei Tian and Qianqian Ren
Crystals 2024, 14(3), 273; https://doi.org/10.3390/cryst14030273 - 13 Mar 2024
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Multi-source ferrous metallurgical dust and sludge are significant components of iron-containing solid waste in the iron and steel industry. It is crucial for the sustainable operation of steel enterprises to recycle iron from ferrous metallurgical dust and sludge (FMDS) for use in steel
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Multi-source ferrous metallurgical dust and sludge are significant components of iron-containing solid waste in the iron and steel industry. It is crucial for the sustainable operation of steel enterprises to recycle iron from ferrous metallurgical dust and sludge (FMDS) for use in steel smelting. However, besides Fe, FMDS also contains valuable elements such as Zn, Pb, K, and Na, among others. While these valuable elements hold high recovery value, they impede the direct reuse of FMDS by iron and steel enterprises. This paper introduces the compositional characteristics of multi-source ferrous metallurgical dust and sludge, analyzes the main recycling technologies associated with FMDS at the present stage of development, and discusses the characteristics of different technologies. In view of this, a new idea of the “cooperative treatment of multi-source ferrous metallurgical dust and sludge—full quantitative recovery of valuable elements” is put forward. This new idea integrates a variety of treatment processes to directly recycle FMDS within the steel plant, enhancing the adequacy of dust and sludge recovery and reducing the risk of environmental pollution. This paper provides a reference for achieving the full quantification and utilization of high-value-added FMDS in steel plants.
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Open AccessArticle
Molecular Dynamics Study of Friction between Ag Nanoparticle and Two-Dimensional Titanium Carbide Ti2C (MXene)
by
Vadym Borysiuk, Iakov A. Lyashenko and Valentin L. Popov
Crystals 2024, 14(3), 272; https://doi.org/10.3390/cryst14030272 - 12 Mar 2024
Abstract
We report the results of atomistic simulations of friction between two-dimensional titanium carbide Ti2C (MXene) and a silver nanoparticle located on its surface. Numerical experiments were performed within classical molecular dynamics methods using a previously developed scheme for simulations of interactions
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We report the results of atomistic simulations of friction between two-dimensional titanium carbide Ti2C (MXene) and a silver nanoparticle located on its surface. Numerical experiments were performed within classical molecular dynamics methods using a previously developed scheme for simulations of interactions between MXenes and metal nanoparticles. In the computer experiments performed, both tangential and shear forces were applied to the Ag nanoparticle to initiate its sliding on the surface of the Ti2C MXene. During the simulations, the nanotribological parameters of the studied system, such as the friction force, contact area, friction coefficient, and tangential shear, were computed. It is shown that, for the studied system, the friction coefficient does not depend on the velocity of nanoparticle movement or the contact area. Additionally, the sliding friction of the nanoparticle on the flexible substrate was considered. The latter case is characterized by a larger friction coefficient and contact area due to the formation of wrinkles on the surface of the substrate.
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(This article belongs to the Special Issue Advanced Research in 2D Materials)
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Low-Temperature Manufacture of Cubic-Phase Li7La3Zr2O12 Electrolyte for All-Solid-State Batteries by Bed Powder
by
Taehong Park, Sunho Lee and Dong-Min Kim
Crystals 2024, 14(3), 271; https://doi.org/10.3390/cryst14030271 - 11 Mar 2024
Abstract
As the demand for battery technology with enhanced safety and high energy density increases, solid-state batteries are currently attracting attention as a solution to problems such as fire and explosion risks associated with lithium-ion batteries. In this study, experiments were conducted to synthesize
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As the demand for battery technology with enhanced safety and high energy density increases, solid-state batteries are currently attracting attention as a solution to problems such as fire and explosion risks associated with lithium-ion batteries. In this study, experiments were conducted to synthesize and optimize Li7La3Zr2O12 (LLZO), a solid electrolyte that is a key component of lithium-ion batteries with stability and high energy density. Experimental results showed that sintering at a low temperature of 800 °C for 8 h was the optimal synthesis and sintering time. Additionally, the excess lithium-containing bed powder enabled the production of pure cubic-phase LLZO. Through a sintering process that creates a lithium atmosphere on the bottom surface and facilitates lithium replenishment, an additional tunnel was introduced between the specimen and the alumina powder, allowing the bottom surface of the specimen to be exposed to the lithium atmosphere. By manufacturing a uniform cubic electrolyte, the path to manufacturing all-solid-state batteries was opened. These findings provide a new approach to forming cubic-phase LLZO with much higher ionic conductivity than the tetragonal phase at low sintering temperatures.
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(This article belongs to the Special Issue Recent Advances and Perspectives in Electrolysis Processes)
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Open AccessReview
Floating Zone Growth of Pure and Pb-Doped Bi-2201 Crystals
by
Maria Roslova, Bernd Büchner and Andrey Maljuk
Crystals 2024, 14(3), 270; https://doi.org/10.3390/cryst14030270 - 11 Mar 2024
Abstract
In this review, we summarize recent progress in crystal growth and understanding of the influence of crystal structure on superconductivity in pure and Pb-doped Bi2Sr2CuOy (Bi-2201) materials belonging to the overdoped region of high-temperature cuprate superconductors. The crystal
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In this review, we summarize recent progress in crystal growth and understanding of the influence of crystal structure on superconductivity in pure and Pb-doped Bi2Sr2CuOy (Bi-2201) materials belonging to the overdoped region of high-temperature cuprate superconductors. The crystal growth of Bi-2201 superconductors faces challenges due to intricate materials chemistry and the lack of knowledge of corresponding phase diagrams. Historically, a crucible-free floating zone method emerged as the most promising growth approach for these materials, resulting in high-quality single crystals. This review outlines the described methods in the literature and the authors’ synthesis endeavors encompassing Pb-doped Bi-2201 crystals, provides a detailed structural characterization of as-grown and post-growth annealed samples, and highlights optimal growth conditions that yield large-size, single-phase, and compositionally homogeneous Bi-2201 single crystals.
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(This article belongs to the Section Inorganic Crystalline Materials)
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Open AccessArticle
Mechanical Response of Cu/Sn58Bi-xNi/Cu Micro Solder Joint with High Temperatures
by
Xiangxia Kong, Junjun Zhai, Ruipeng Ma, Fenglian Sun and Xuemei Li
Crystals 2024, 14(3), 269; https://doi.org/10.3390/cryst14030269 - 10 Mar 2024
Abstract
Sn58Bi solder is considered a promising lead-free solder that meets the performance requirements, with the advantages of good wettability and low cost. However, the low melting point characteristic of Sn58Bi poses a serious threat to the high-temperature reliability of electronic products. In this
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Sn58Bi solder is considered a promising lead-free solder that meets the performance requirements, with the advantages of good wettability and low cost. However, the low melting point characteristic of Sn58Bi poses a serious threat to the high-temperature reliability of electronic products. In this study, Sn58Bi solder alloy based on nickel (Ni) functionalization was successfully synthesized, and the effect of a small amount of Ni on creep properties and hardness of Cu/Sn58Bi/Cu micro solder joints at different temperatures (25 °C, 50 °C, 75 °C, 100 °C) was investigated using a nanoindentation method. The results indicate that the nanoindentation depth of micro solder joints exhibits a non-monotonic trend with increasing Ni content at different temperatures, and the slope of the indentation stage curve decreases at 100 °C, showing that the micro solder joints undergo high levels of softening. According to the observation of indentation morphology, Ni doping can reduce the indentation area and accumulation around the indentation, especially at 75 °C and 100 °C. In addition, due to the severe creep phenomenon at 100 °C, the indentation hardness rapidly decreases. The indentation hardness values of micro solder joints of Cu/Sn58Bi/Cu, Cu/Sn58Bi-0.1Ni/Cu, and Cu/Sn58Bi-0.2Ni/Cu at 100 °C are 14.67 ± 2.00 MPa, 21.05 ± 2.00 MPa, and 20.13 ± 2.10 MPa, respectively. Nevertheless, under the same temperature test conditions, the addition of Ni elements can improve the high-temperature creep resistance and hardness of Cu/Sn58Bi/Cu micro solder joints.
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(This article belongs to the Special Issue Welding Dissimilar Materials)
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Open AccessArticle
Effect of Traps on the UV Sensitivity of Gallium Oxide-Based Structures
by
Vera M. Kalygina, Alexander V. Tsymbalov, Petr M. Korusenko, Aleksandra V. Koroleva and Evgeniy V. Zhizhin
Crystals 2024, 14(3), 268; https://doi.org/10.3390/cryst14030268 - 09 Mar 2024
Abstract
Resistive metal/β-Ga2O3/metal structures with different interelectrode distances and electrode topologies were investigated. The oxide films were deposited by radio-frequency magnetron sputtering of a Ga2O3 (99.999%) target onto an unheated sapphire c-plane substrate (0001) in an Ar/O
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Resistive metal/β-Ga2O3/metal structures with different interelectrode distances and electrode topologies were investigated. The oxide films were deposited by radio-frequency magnetron sputtering of a Ga2O3 (99.999%) target onto an unheated sapphire c-plane substrate (0001) in an Ar/O2 gas mixture. The films are sensitive to ultraviolet radiation with wavelength λ = 254. Structures with interdigital electrode topology have pronounced persistent conductivity. It is shown that the magnitude of responsivity, response time τr, and recovery time τd are determined by the concentration of free holes p involved in recombination processes. For the first time, it is proposed to consider hole trapping both by surface states Nts at the metal/Ga2O3 interface and by traps in the bulk of the film.
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(This article belongs to the Special Issue 1D and 2D Nanomaterials for Sensor Applications)
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Open AccessArticle
Synthesis of BaZrS3 and BaS3 Thin Films: High and Low Temperature Approaches
by
Tim Freund, Sumbal Jamshaid, Milad Monavvar and Peter Wellmann
Crystals 2024, 14(3), 267; https://doi.org/10.3390/cryst14030267 - 09 Mar 2024
Abstract
Current research efforts in the field of the semiconducting chalcogenide perovskites are directed towards the fabrication of thin films and subsequently determine their performance in the photovoltaic application. These efforts are motivated by the outstanding properties of this class of materials in terms
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Current research efforts in the field of the semiconducting chalcogenide perovskites are directed towards the fabrication of thin films and subsequently determine their performance in the photovoltaic application. These efforts are motivated by the outstanding properties of this class of materials in terms of stability, high absorption coefficient near the band edge and no significant health concerns compared to their halide counterparts. The approach followed here is to use stacked precursor layers and is adopted from other chalcogenide photovoltaic materials like the kesterites and chalcopyrites. The successful synthesis of BaZrS3 from stacked layers of BaS and Zr and annealing at high temperatures (~1100 °C) with the addition of elemental sulfur is demonstrated. However, the film shows the presence of secondary phases and a flawed surface. As an alternative to this, BaS3 could be used as precursor due to its low melting point of 554 °C. Previously, the fabrication of BaS3 films was demonstrated, but in order to utilize them in the fabrication of BaZrS3 thin films, their microstructure and processing are further improved in this work by reducing the synthesis temperature to 300 °C, resulting in a smoother surface. This work lays the groundwork for future research in the fabrication of chalcogenide perovskites utilizing stacked layers and BaS3.
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(This article belongs to the Special Issue Perovskites – New and Old Materials)
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Open AccessArticle
A Multiband and Multifunctional Metasurface for Linear and Circular Polarization Conversion in Reflection Modes
by
Saima Hafeez, Jianguo Yu, Fahim Aziz Umrani, Wang Yun and Muhammad Ishfaq
Crystals 2024, 14(3), 266; https://doi.org/10.3390/cryst14030266 - 08 Mar 2024
Abstract
Multifunctional integrated meta-devices are the demand of modern communication systems and are given a lot of attention nowadays. Most of the research has focused on either cross-polarization conversion (CPC) or linear-to-circular (LP–CP) conversion. However, simultaneously realizing multiple bands with good conversion efficiency remains
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Multifunctional integrated meta-devices are the demand of modern communication systems and are given a lot of attention nowadays. Most of the research has focused on either cross-polarization conversion (CPC) or linear-to-circular (LP–CP) conversion. However, simultaneously realizing multiple bands with good conversion efficiency remains crucial. This paper proposes a multiband and multifunctional dual reflective polarization converter surface capable of converting a linearly polarized (LP) wave into a circularly polarized (CP) wave, in frequency bands of 12.29–12.63 GHz, 16.08–24.16 GHz, 27.82–32.21 GHz, 33.75–38.74 GHz, and 39.70–39.79 GHz, with 3 dB axial ratio bandwidths of 2.7%, 40.15%, 14.6%, 13.76%, and 0.2%, respectively. Moreover, the converter is capable of achieving CPC with a polarization conversion ratio (PCR) that exceeds 95%, within the frequency ranges of 13.10–14.72 GHz, 25.43–26.00, 32.46–32.56 GHz, and 39.14–39.59 GHz. In addition, to identify the fundamental cause of the CPC and LP–CP conversion, a comprehensive theoretical investigation is provided. Furthermore, the surface current distribution patterns at different frequencies are investigated to analyze the conversion phenomena. A sample prototype consisting of 20 × 20 unit cells was fabricated and measured, verifying our design and the simulated results. The proposed structure has potential applications in satellite communications, radar, stealth technologies, and reflector antennas.
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(This article belongs to the Special Issue Anisotropic Acoustic Metamaterials)
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Automatic Detection of Cast Billet Dendrite Based on Improved Hough Transform
by
Yuhan Wang, Qing He and Zhi Xie
Crystals 2024, 14(3), 265; https://doi.org/10.3390/cryst14030265 - 08 Mar 2024
Abstract
Primary dendrite information is one of the most important metrics to measure the quality of continuous cast slabs. The contrast of low magnification images is very low under the influence of illumination and sampling devices, so the traditional dendrite detection method has the
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Primary dendrite information is one of the most important metrics to measure the quality of continuous cast slabs. The contrast of low magnification images is very low under the influence of illumination and sampling devices, so the traditional dendrite detection method has the problem of missed detections. We propose an automatic dendrite detection method based on an improved Hough transform, which effectively improves the accuracy and efficiency of primary dendrite detection. By using the local grayscale features of the image, a genetic algorithm-based local contrast enhancement algorithm is proposed. Compared with the traditional contrast enhancement algorithm, it can retain all the information of the dendrites. Combined with the image binarization method based on Hessian matrix, we can obtain more detailed information about the dendrites. According to the continuity and solidification characteristics of dendrites, the Hough transform is improved to extract dendrite information, which effectively reduces the computational cost of the Hough transform. The experimental results show that the method of this paper has versatility, and the error is four pixels compared with the manual method, which can provide a reliable basis for the subsequent judgement of the quality of cast billets.
Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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