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Crystals
Volume 16
Issue 3
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Crystals, Volume 16, Issue 3 (March 2026) – 62 articles

Cover Story (view full-size image): Phenothiazine is a heteroaromatic electron donor with broad applications ranging from materials science to pharmaceuticals. Central to its function in chemical and biological systems is its ability to engage in diverse noncovalent interactions, including halogen and π-stacked charge-transfer bonding. This article combines X-ray crystallography and DFT calculations to examine complexes of phenothiazine with halogen-bond donors, π-acceptors, and multifunctional partners. The results reveal a clear preference for π-stacking over halogen bonding, driven primarily by stronger dispersion interactions, and provide insight into the hierarchy and origin of intermolecular interactions in phenothiazine-based systems. View this paper
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16 pages, 1253 KB  
Article
Periodic DFT Investigation of Isosymmetric Alpha–Beta Phase Transition in Resorcinol Under Ambient and High Pressure
by Anna Maria Mazurek, Monika Franczak-Rogowska and Łukasz Szeleszczuk
Crystals 2026, 16(3), 215; https://doi.org/10.3390/cryst16030215 - 23 Mar 2026
Viewed by 542
Abstract
Isosymmetric phase transitions driven by subtle hydrogen-bond rearrangements remain challenging for periodic density functional theory (DFT), particularly when energy differences between polymorphs are small. Resorcinol represents an interesting case in which the α and β polymorphs crystallize in the same space group and [...] Read more.
Isosymmetric phase transitions driven by subtle hydrogen-bond rearrangements remain challenging for periodic density functional theory (DFT), particularly when energy differences between polymorphs are small. Resorcinol represents an interesting case in which the α and β polymorphs crystallize in the same space group and differ primarily in hydroxyl orientation and hydrogen-bond topology. In this work, the α–β phase transition was systematically investigated using periodic DFT calculations under ambient and elevated pressure. A broad set of exchange–correlation functionals combined with different dispersion corrections was benchmarked against experimental structural and energetic data. Dispersion-corrected methods were essential for reproducing lattice parameters and the pressure-induced inversion of stability. PBESOL with Tkatchenko–Scheffler dispersion provided the most consistent agreement with the experiment and was therefore used for phonon and ab initio molecular dynamics simulations. Phonon-derived thermodynamic analysis revealed a delicate enthalpy–entropy balance governing the transition, strongly affected by pressure. Dynamical simulations confirmed the instability of the α phase under compression, demonstrating the cooperative nature of this hydrogen-bond-driven isosymmetric transformation. Full article
(This article belongs to the Special Issue Density Functional Theory (DFT) in Crystalline Material)
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12 pages, 1677 KB  
Article
First-Principles Study of the Structural Evolution of Microcline Under High Pressure
by Baoyun Wang and Meisu Xiang
Crystals 2026, 16(3), 214; https://doi.org/10.3390/cryst16030214 - 23 Mar 2026
Viewed by 489
Abstract
Microcline is an important rock-forming mineral in the Earth’s crust, and characterizing its structural behavior under compression is essential for understanding the high-pressure response of feldspar minerals under geological conditions. In this study, the crystal structural evolution of microcline up to 12 GPa [...] Read more.
Microcline is an important rock-forming mineral in the Earth’s crust, and characterizing its structural behavior under compression is essential for understanding the high-pressure response of feldspar minerals under geological conditions. In this study, the crystal structural evolution of microcline up to 12 GPa was investigated using first-principles calculations based on density functional theory. The results reveal an isosymmetric phase transition at approximately 6–7 GPa, accompanied by a ~7% volume collapse. Across this transition, the b-axis and unit-cell angles (α, β, γ) change abruptly, and the aluminum coordination transforms from fourfold to a distorted fivefold geometry intermediate between a trigonal bipyramid and a square pyramid. Analysis of bond lengths and angles indicates that compression in the low-pressure phase is primarily driven by shear deformation of tetrahedral Ring 1. Near the transition pressure, however, marked shear deformations of Ring 2 and Ring 3 induce a strong contraction of the b-axis and abrupt changes in the unit-cell angles. Comparison with the compression behavior of low albite reveals both similarities and distinct structural responses, highlighting the role of framework topology and extra-framework cations in controlling pressure-induced structural evolution in feldspar minerals. These results provide new insights into the high-pressure behavior of microcline and contribute to a better understanding of the structural stability of feldspar minerals in the Earth’s interior. Full article
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14 pages, 3959 KB  
Article
Mechanochemical Evolution of Ni50Ti30Zr20 Alloy During High-Energy Ball Milling
by Thobani Paul Shangase, Maria Ntsoaki Mathabathe and Charles Witness Siyasiya
Crystals 2026, 16(3), 213; https://doi.org/10.3390/cryst16030213 - 20 Mar 2026
Viewed by 511
Abstract
The fabrication of NiTiZr alloys by solid-state routes remains challenging due to limited atomic diffusion and the high reactivity of Ti and Zr. Mechanical alloying offers a potential pathway for synthesising such systems; however, complete alloy formation is not always achieved under practical [...] Read more.
The fabrication of NiTiZr alloys by solid-state routes remains challenging due to limited atomic diffusion and the high reactivity of Ti and Zr. Mechanical alloying offers a potential pathway for synthesising such systems; however, complete alloy formation is not always achieved under practical milling conditions. Researchers have infrequently explored the mechanical alloying of NiTiZr, and this study systematically investigates the effect of milling time on microstructural evolution rather than claiming complete alloy synthesis. A high-energy planetary ball mill was used to mechanically process elemental powders of Ni, Ti, and Zr for 5–28 h. The examination revealed that longer milling times resulted in progressive crystallite refinement and increased lattice strain, while particle morphology evolved from irregular to more globular shapes due to repeated fracture and cold welding. After 28 h of milling, limited reacted regions containing Ni, Ti, and Zr were observed (~4.6% area fraction), while most of the powder remained heterogeneous and polyphasic, with no evidence of complete Ni50Ti30Zr20 alloy formation. X-ray diffraction showed significant peak broadening without systematic 2θ peak shifts, indicating severe plastic deformation and crystallite refinement rather than definitive solid-solution formation of the allot. Differential scanning calorimetry revealed exothermic thermal events between 300 °C and 470 °C, which are attributed to defect recovery and thermally activated structural rearrangements rather than confirmed martensitic or crystallisation transformations. These results demonstrate that high-energy ball milling alone is effective for particle size reduction and defect generation but insufficient for producing a fully homogeneous Ni50Ti30Zr20 alloy within 28 h. Additional activation energy, such as post-milling heat treatment or extended processing, is required to promote complete alloying in this system. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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14 pages, 2739 KB  
Article
Preparation of Polymerizable Mechanochromic Gelator
by Mizuho Kondo, Tsuyoshi Iida, Sho Iida and Nobuhiro Kawatsuki
Crystals 2026, 16(3), 212; https://doi.org/10.3390/cryst16030212 - 20 Mar 2026
Viewed by 373
Abstract
Mechanochromism is a phenomenon in which mechanical stimuli change the optical properties of a material, such as its color and emission properties. Various materials exhibiting this behavior have been intensively studied. Mechanochromic materials that exploit liquid crystals have been previously reported. Using liquid [...] Read more.
Mechanochromism is a phenomenon in which mechanical stimuli change the optical properties of a material, such as its color and emission properties. Various materials exhibiting this behavior have been intensively studied. Mechanochromic materials that exploit liquid crystals have been previously reported. Using liquid crystals, properties different from those of conventional materials, such as anisotropic response and multicolored luminescence due to intermediate aggregation phase stabilization, can be expected. Recently, we reported the preparation and evaluation of the optical properties of liquid-crystalline mechanochromic dyes with cholesterol terminals. The dyes formed gels in some solvents, changed their emission color, and exhibited a friable response without reaching a crystalline state. In addition, film-forming properties, processability, and responsiveness were improved in thin films mixed with polymers. However, the mechanical and thermal stabilities of the gels were low. In this study, a compound similar to the polymerizable unit was synthesized to produce tougher gels. In addition, triblock polymers with a mechanoresponsive dye in the hard segment were synthesized. The xerogel film prepared from the monomer showed an irreversible blue shift in photoluminescent color by mechanical grinding and also exhibited linearly polarized photoluminescence by uniaxial grinding due to force-induced alignment. On the other hand, the xerogel film prepared from the triblock copolymer showed a blue shift in photoluminescent color that can approximately revert to the initial state by thermal annealing, though it showed no anisotropy by uniaxial grinding, indicating that polymerization partially preserves mechanical responsiveness. Full article
(This article belongs to the Section Liquid Crystals)
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14 pages, 4770 KB  
Article
Microstructural Evolution and Precipitate Control in Boron-Doped Ni-Mn-Ti Shape Memory Alloys via Thermal Processing
by Na Liu, Marcia Ahn, Subrata Ghosh, Dipika Mandal, Bed Poudel and Wenjie Li
Crystals 2026, 16(3), 211; https://doi.org/10.3390/cryst16030211 - 20 Mar 2026
Viewed by 591
Abstract
Elastocaloric cooling, which leverages stress-induced phase transformation in shape memory materials, represents a sustainable and energy-efficient alternative to conventional vapor-compression cooling systems. Central to optimizing these materials is understanding how thermal processing history dictates phase formation, microstructure, and thermal properties. In this study, [...] Read more.
Elastocaloric cooling, which leverages stress-induced phase transformation in shape memory materials, represents a sustainable and energy-efficient alternative to conventional vapor-compression cooling systems. Central to optimizing these materials is understanding how thermal processing history dictates phase formation, microstructure, and thermal properties. In this study, we investigated the (Ni50Mn31.5Ti18)99.8B0.2 compound synthesized via vacuum induction melting and arc melting, followed by water quenching. Induction melting results in needle-like, boron-rich precipitates within the martensite lattice. In contrast, vacuum arc melting promoted precipitate growth at the grain boundaries. The vacuum arc melting sample exhibits ~82% martensite phase fraction, a near-ambient transformation temperature of ~277 K, a large transition entropy change of ~75 J·kg−1·K−1, and moderate thermal hysteresis of ~24 K. These results underscore the pivotal role of thermal history in tailoring phase stability and transformation thermodynamics, providing essential design guidelines for subsequent mechanical performance optimization in elastocaloric shape memory alloys for energy-efficient and sustainable thermal management applications. Full article
(This article belongs to the Special Issue Applications of Crystalline Materials in Elastocaloric Devices)
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27 pages, 4016 KB  
Review
Design- and Optimization-Oriented Composition and Morphology Engineering for MOF-Derived Microwave Absorbers
by Qixue Xu, Yuanrui Qu, Xue Zhu, Cheng Xiang, Mingli Huang, Hongmei Li, Linlin Ning and Jun Jia
Crystals 2026, 16(3), 210; https://doi.org/10.3390/cryst16030210 - 19 Mar 2026
Viewed by 808
Abstract
In recent decades, the requirement for materials with excellent electromagnetic wave (EMW) absorption properties has been steadily expanding. Developing and designing multifunctional hybrid absorbers featuring diverse components and synergistic loss mechanisms have become a significant research field. MOF materials feature abundant heterogeneous interfaces [...] Read more.
In recent decades, the requirement for materials with excellent electromagnetic wave (EMW) absorption properties has been steadily expanding. Developing and designing multifunctional hybrid absorbers featuring diverse components and synergistic loss mechanisms have become a significant research field. MOF materials feature abundant heterogeneous interfaces and high porosity, and their derivatives exhibit superior magnetic effects. They can enhance EMW absorption through multiple scattering and reflection. These merits enable them to satisfy the demands of diverse EMW absorption applications. Therefore, this work summarizes the investigations and applications of MOF derivatives in EMW absorption. The EMW absorption mechanisms of MOF derivatives are thoroughly investigated from the aspects of precursor design, framework construction, and compounding with reinforcing phases. Meanwhile, the research progress of related materials is summarized, including multi-component MOF-derived EMW absorbers, MOF-derived biomass composite absorbing materials, and MOF-derived conductive polymer composite absorbers. In addition, the subsequent progress of EMW absorbers shows promising prospects. The various deficiencies of MOF-derived absorbers in current research are also analyzed. It is expected to provide more systematic and thorough guidance for the future investigations in related fields. Full article
(This article belongs to the Section Hybrid and Composite Crystalline Materials)
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19 pages, 3112 KB  
Article
Load Separation Criterion for Ductile Fracture Characterization of Thin Aluminum Sheets
by Mohammed Y. Abdellah, Fawaz M. Abdullah, Abdulrahman M. Al-Ahmari and Mohamed K. Hassan
Crystals 2026, 16(3), 209; https://doi.org/10.3390/cryst16030209 - 19 Mar 2026
Viewed by 382
Abstract
The characterization of ductile fracture in thin metallic sheets is challenging due to extensive plastic deformation and stable crack growth under plane-stress conditions. This study investigates the applicability of the load separation criterion as a single-specimen method for evaluating fracture behavior in thin [...] Read more.
The characterization of ductile fracture in thin metallic sheets is challenging due to extensive plastic deformation and stable crack growth under plane-stress conditions. This study investigates the applicability of the load separation criterion as a single-specimen method for evaluating fracture behavior in thin aluminum sheets. Experimental tests were performed on double-edge-notched tension (DENT) specimens manufactured from a 1.2 mm thick commercial aluminum sheet with ligament lengths ranging from 4 to 20 mm. Load–displacement responses were analyzed using curve-fitting techniques to determine the separation parameter, geometry function, plastic η-factor, and the plastic component of the J-integral. The separation parameter stabilized in the plastic regime, and the geometry function followed a power-law relationship with the normalized ligament ratio, confirming the validity of the load separation assumption. The calculated fracture toughness values showed consistent averages of approximately 58–60 kJ/m2 across different fitting approaches, which are in good agreement with the essential work of fracture (EWF) value of about 51.5 kJ/m2 reported for the same material. These results demonstrate that the load separation approach provides a reliable and efficient framework for determining fracture parameters in thin ductile aluminum sheets using a single specimen. The methodology offers practical advantages for fracture assessment and structural integrity analysis of lightweight sheet structures in aerospace, automotive, and marine applications. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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21 pages, 24294 KB  
Article
Effect of Zinc Content on the Mechanical, Corrosion, Tribological and Electrical Properties of Spark Plasma-Sintered Copper/Graphene Composites
by Serdar Özkaya, Yaren Adabaş, Müslim Çelebi, Abdullah Hasan Karabacak and Ertuğrul Çelik
Crystals 2026, 16(3), 208; https://doi.org/10.3390/cryst16030208 - 19 Mar 2026
Viewed by 619
Abstract
Copper-based hybrid metal matrix composites reinforced with graphene and zinc were developed to achieve a balanced combination of mechanical strength, corrosion resistance, wear performance, and electrical conductivity. In this study, Cu matrix composites containing a constant graphene content of 1 wt.% and varying [...] Read more.
Copper-based hybrid metal matrix composites reinforced with graphene and zinc were developed to achieve a balanced combination of mechanical strength, corrosion resistance, wear performance, and electrical conductivity. In this study, Cu matrix composites containing a constant graphene content of 1 wt.% and varying Zn contents (0, 5, 10, and 15 wt.%) were fabricated through mechanical alloying followed by Spark Plasma Sintering (SPS). The effects of zinc content on microstructure, densification, hardness, corrosion behavior, tribological performance, and electrical conductivity were systematically investigated. Microstructural analyses revealed that the combined use of graphene and Zn significantly influenced grain refinement, interfacial stability, and densification behavior. The composite containing 10 wt.% Zn exhibited the highest relative density (~90.5%) and maximum hardness (62 HB), indicating an optimal reinforcement level. Corrosion tests conducted in 3.5 wt.% NaCl solution demonstrated that the 10 wt.% Zn composite showed the most noble corrosion potential and the lowest corrosion current density, which was attributed to reduced porosity and improved microstructural homogeneity. Tribological results confirmed that graphene contributed to a self-lubricating effect, while Zn enhanced load-bearing capacity, leading to improved wear resistance under increasing normal loads. Electrical conductivity measurements showed a gradual decrease with increasing Zn content, mainly due to solid-solution-induced electron scattering in the Cu matrix; however, the fixed graphene addition and effective SPS consolidation helped preserve conductive pathways, allowing all composites to retain acceptable conductivity levels. The results indicate that the hybrid Cu–graphene–Zn composites exhibit a balanced combination of mechanical, corrosion, tribological, and electrical properties, with 10 wt.% Zn emerging as the optimal composition. Full article
(This article belongs to the Special Issue Performance and Processing of Metal Materials)
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14 pages, 4006 KB  
Article
Controlled Growth of Large-Area Graphite Single Crystals at Atmospheric Pressure and High Temperature from a Metal Flux
by Thomas Poirier, Dylan Evans, Ishika Thakur, Morgen L. Smith, Placidus B. Amama, Gaihua Ye, Rui He and James H. Edgar
Crystals 2026, 16(3), 207; https://doi.org/10.3390/cryst16030207 - 18 Mar 2026
Viewed by 504
Abstract
In this study, the growth of high-quality graphite single crystals from a molten metal flux at atmospheric pressure was optimized. The crystals were precipitated from a saturated iron–carbon solution by slowly cooling (4 °C/h) from a maximum temperature to reduce the carbon solubility. [...] Read more.
In this study, the growth of high-quality graphite single crystals from a molten metal flux at atmospheric pressure was optimized. The crystals were precipitated from a saturated iron–carbon solution by slowly cooling (4 °C/h) from a maximum temperature to reduce the carbon solubility. The graphite flakes were >25 square millimeters in area and >10 microns thick, with individual crystal grains as large as 1.2 mm2. The crystals were (0002) oriented, as determined by X-ray diffraction. The high structural quality of the graphite crystals was verified by Raman spectroscopy. For graphite with the natural distribution of carbon isotopes, the G-peak at 1580 cm−1 was narrow (~12 cm−1) and the defect peak (D-peak) was absent. To demonstrate the process versatility, graphite crystals enriched in the 13C isotope were grown at 5 degrees of enrichment. The Raman G-peak linearly shifted from 1580 cm−1 to 1520 cm−1 for graphite crystals enriched from 1 to 99% 13C. The etch pit densities from defect-sensitive etching ranged from 0 to 1.6 × 108 per cm2. The process was refined by examining the grain size and quality as functions of the carbon concentration in the starting sources, the carrier gas composition, and maximum temperature. The simplicity of this process suggests it can be scaled to produce very large graphite crystals that would be suitable for a wide range of technologies. Full article
(This article belongs to the Section Crystal Engineering)
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13 pages, 2188 KB  
Article
Positional Methyl Effects in Benzo[e][1,2,4]triazines—Synthesis and Crystal Structure Analysis of 5-Methyl-3-phenylbenzo[e][1,2,4]triazine and Its Precursor, N′-(3-Methyl-2-nitrophenyl)benzohydrazide
by Christos P. Constantinides, Jin-Seok Yi, Haidar Dakdouk and Simona Marincean
Crystals 2026, 16(3), 206; https://doi.org/10.3390/cryst16030206 - 18 Mar 2026
Viewed by 589
Abstract
We report the synthesis, spectroscopic characterization, and single-crystal X-ray structures of 5-methyl-3-phenylbenzo[e][1,2,4]triazine (I) and its precursor N′-(3-methyl-2-nitrophenyl)benzohydrazide (IV). Compound IV was obtained by nucleophilic aromatic substitution of 1-fluoro-3-methyl-2-nitrobenzene with benzohydrazide and was converted to I through [...] Read more.
We report the synthesis, spectroscopic characterization, and single-crystal X-ray structures of 5-methyl-3-phenylbenzo[e][1,2,4]triazine (I) and its precursor N′-(3-methyl-2-nitrophenyl)benzohydrazide (IV). Compound IV was obtained by nucleophilic aromatic substitution of 1-fluoro-3-methyl-2-nitrobenzene with benzohydrazide and was converted to I through a reductive cyclodehydration/oxidative aromatization sequence. The present study provides a concise route to the 5-methyl regioisomer together with full structural characterization and examines how methyl substitution at the 5-position influences molecular geometry and crystal packing relative to the previously reported 6- and 8-methyl analogs. X-ray analysis shows that IV adopts a conjugated hydrazide framework with a twisted N–N linkage and an out-of-plane nitro group. In the crystal, it forms one-dimensional N–H⋯O hydrogen-bonded chains further assembled by weaker intermolecular contacts. By contrast, I displays an essentially planar benzo[e][1,2,4]triazine core with an almost coplanar phenyl substituent and packs into slipped π-stacked columns reinforced by secondary C–H⋯N contacts. Comparison with the previously reported methyl regioisomers shows that relocation of the methyl group to the 5-position has little effect on the intrinsic molecular geometry of the benzo[e][1,2,4]triazine scaffold, while subtly modulating the stacking arrangement and secondary packing interactions in the solid state. These results further define the role of methyl-substituent position in shaping the supramolecular organization of 3-phenylbenzo[e][1,2,4]triazines. Full article
(This article belongs to the Section Organic Crystalline Materials)
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16 pages, 3962 KB  
Article
A Study of the Influence of a Nanostructured Activating Component in Welding Electrodes on the Formation of Welding Beads
by Rustam Saidov, Rustam Rakhimov, Kamel Touileb and Joffine Ponore
Crystals 2026, 16(3), 205; https://doi.org/10.3390/cryst16030205 - 18 Mar 2026
Cited by 1 | Viewed by 503
Abstract
The objective of this work was to investigate the effect of a special activating component, under the ZB-3 brand, on the welding and technological properties of a welding electrode when incorporated into the coating of a rutile welding electrode. Pulsed radiation activation was [...] Read more.
The objective of this work was to investigate the effect of a special activating component, under the ZB-3 brand, on the welding and technological properties of a welding electrode when incorporated into the coating of a rutile welding electrode. Pulsed radiation activation was used to produce the nanostructured activating component ZB-3. The results showed the beneficial effect of the electrode doped with ZB-3 on the formation of welding beads. At the same time, an improvement in the quality of weld formation is observed with a ZB-3 activator content of up to 8%. The qualities of the weld formation were significantly improved. Also, an increase in the breaking length of the electrode arc by more than 10% was established with a ZB-3 activator content of up to 2%, and the depth of penetration of the welded metal increased to 40%. Full article
(This article belongs to the Special Issue Welding and Joining of Metallic Materials: Microstructure and Mechanical Properties, 2nd Edition)
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23 pages, 4564 KB  
Article
Influence of Binary Precursors on Wood Biomass Ash-Based Alkali-Activated Materials: A Comparative Study
by Yiying Du, Jolanta Pranckevičienė and Ina Pundienė
Crystals 2026, 16(3), 204; https://doi.org/10.3390/cryst16030204 - 17 Mar 2026
Viewed by 616
Abstract
The valorisation of significant quantities of wood biomass ash (WBA) in the production of building and construction materials is a sustainable approach to waste management. Due to their low chemical reactivity, the challenge for WBA-based alkali-activated materials (AAM) is improving their mechanical properties. [...] Read more.
The valorisation of significant quantities of wood biomass ash (WBA) in the production of building and construction materials is a sustainable approach to waste management. Due to their low chemical reactivity, the challenge for WBA-based alkali-activated materials (AAM) is improving their mechanical properties. To address this issue, WBA, containing wood biomass bottom ash and wood biomass fly ash, was used as the primary precursor. One aluminosilicate-rich material (coal fly ash (CFA), metakaolin (MK), or natural zeolite (NZ)) was added as a binary precursor at 10, 20, 30, and 40% of the total precursor mass (the mass of WBA plus the binary precursor) to compare its effectiveness. In the overall composition, the proportion of these aluminosilicate precursors was only 3.3–13.3%. Alkali activators consisted of 10% calcium hydroxide, 7 mol/L sodium hydroxide, and sodium silicate with the same solute mass as sodium hydroxide. Compressive strength and microstructural examinations (SEM-EDS, TG-DTA, XRD, XRF, and FTIR) were conducted on the produced AAM to analyse the mechanical performance and reaction mechanisms. A cradle-to-gate lifecycle assessment (LCA) was performed to evaluate the environmental impacts, including greenhouse gas emissions and energy consumption. The results show that NZ increased compressive strength by up to 57.62% when used at 6.6% in the composition. At the same time, MK and CFA increased strength by 33.05% and 47.15%, respectively. Binary precursors increased the greenhouse gas emissions and energy demands of AAM products, especially the MK, due to its energy-intensive calcination process. From a comprehensive view, NZ is the most efficient choice based on both mechanical and environmental insights. Full article
(This article belongs to the Special Issue Synergizing Crystallography, Mineral Materials Science and Solid Waste Upcycling for Sustainable Materials Innovation)
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14 pages, 2938 KB  
Article
Effect of Crystal-to-Detector Distance Variations on Serial Femtosecond Crystallography Data Collected at PAL-XFEL
by Ki Hyun Nam, Sehan Park and Jaehyun Park
Crystals 2026, 16(3), 203; https://doi.org/10.3390/cryst16030203 - 17 Mar 2026
Viewed by 547
Abstract
Serial femtosecond crystallography (SFX) using X-ray free electron lasers (XFELs) enables the determination of room-temperature structures of biological macromolecules without radiation damage. The accuracy of detector geometry parameters, including the crystal-to-detector distance (CTDD), is critical for reliable data processing. In SFX experiments, the [...] Read more.
Serial femtosecond crystallography (SFX) using X-ray free electron lasers (XFELs) enables the determination of room-temperature structures of biological macromolecules without radiation damage. The accuracy of detector geometry parameters, including the crystal-to-detector distance (CTDD), is critical for reliable data processing. In SFX experiments, the CTDD may shift during data collection due to changes in the experimental setup or installation of the sample delivery system. Such CTDD variations can affect the quality of SFX datasets; however, their impact has not been fully elucidated in the context of SFX data processing. In this study, we investigated the influence of CTDD variations on SFX datasets collected at Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) with thermolysin, lysozyme, and glucose isomerase crystals processed by four indexing algorithms. At the optimized CTDD, the distribution of unit cell parameters exhibited a Gaussian pattern; however, it became distorted as the CTDD deviated further from the optimal value. Data analysis indicated that the CTDD tolerance for successful data processing and structure determination was approximately ±3–5 mm from the optimized CTDD. These findings provide insight into indexing behavior in SFX data processing at PAL-XFEL and offer practical guidance for improving data processing efficiency. Full article
(This article belongs to the Section Biomolecular Crystals)
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16 pages, 12441 KB  
Article
Transformation Behavior of 9Ni Steel Under Continuous Cooling Conditions: Experiments and Simulation
by Weina Han, Lili Guo, Xinyue Liu, Yue Peng and Bin Zhang
Crystals 2026, 16(3), 202; https://doi.org/10.3390/cryst16030202 - 16 Mar 2026
Viewed by 509
Abstract
To investigate the effect of cooling rate on the phase transformation behavior and mechanical properties of 9Ni steel, a 7 mm thick industrial 9Ni steel plate was selected as the research object in this study. The JMatPro software was employed to simulate and [...] Read more.
To investigate the effect of cooling rate on the phase transformation behavior and mechanical properties of 9Ni steel, a 7 mm thick industrial 9Ni steel plate was selected as the research object in this study. The JMatPro software was employed to simulate and calculate key parameters, including the thermodynamic phase diagram, CCT curve, and mechanical properties. Meanwhile, static thermal simulation experiments at cooling rates ranging from 0.5 to 30 °C/s were conducted on a Gleeble-3500 thermal simulation testing machine. Microstructure characterization and property tests were carried out using a metallographic microscope, scanning electron microscope (SEM), and Vickers hardness tester, and the experimental CCT curve was subsequently plotted and compared with the simulation results. The results revealed that the microstructure of 9Ni steel changed regularly with the cooling rate. With the increase in cooling rate, the ferrite content decreased continuously, the bainite content increased initially and then decreased, and the martensite content increased continuously. At a cooling rate of 30 °C/s, the martensite content reached approximately 90%. The microhardness of 9Ni steel initially sharply increased and then stabilized with the increase in cooling rate, stabilizing at 359 HV1 at a cooling rate of 30 °C/s. The phase transformation law of the measured CCT curve is highly consistent with the simulation results, verifying the reliability and accuracy of JMatPro for predicting the phase transformation behavior and mechanical properties of 9Ni steel. This study provides a theoretical basis and data support for the precise optimization of the heat treatment process of 9Ni steel and has important practical significance for enhancing its service performance in cryogenic engineering applications. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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11 pages, 621 KB  
Article
Synthesis and Structures of Ru(II)-p-Cymene Sandwich Complexes with Electron-Withdrawing Cyclopentadienyl Ligands
by Uttam R. Pokharel, Sean Parkin and John P. Selegue
Crystals 2026, 16(3), 201; https://doi.org/10.3390/cryst16030201 - 15 Mar 2026
Viewed by 938
Abstract
A modular synthetic route has been developed to prepare a new series of cationic ruthenium(II) complexes with electron-withdrawing 1,2-diacylcyclopentadienyl ligands. The 2-acyl-6-hydroxyfulvenes were synthesized from cyclopentadienide and acyl chlorides and converted to Tl(I) cyclopentadienyl salts using Tl2SO4/KOH. Transmetalation with [...] Read more.
A modular synthetic route has been developed to prepare a new series of cationic ruthenium(II) complexes with electron-withdrawing 1,2-diacylcyclopentadienyl ligands. The 2-acyl-6-hydroxyfulvenes were synthesized from cyclopentadienide and acyl chlorides and converted to Tl(I) cyclopentadienyl salts using Tl2SO4/KOH. Transmetalation with [Ru(η6-p-cymene)(μ-Cl)Cl]2 followed by PF6− metathesis gives the complexes [Ru{η5-1,2-C5H3(CO–R)2}(η6-p-cymene)][PF6] (R = t-Bu, p-Tol, p-ClC6H4, p-IC6H4) in moderate to high yields. The new compounds were characterized by NMR and IR spectroscopy; mass spectrometry and elemental analysis were performed where applicable. X-ray analysis of one of the complexes confirms that electron-deficient Cp ligands retain η5-coordination and structural planarity within Ru(II)–arene sandwich architectures, highlighting their potential utility in electronically tunable organometallic frameworks. Full article
(This article belongs to the Special Issue Transition Metal Complexes with Heterocyclic Ligands: Structural Insights, Biological Potential, and Computational Perspectives)
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13 pages, 1562 KB  
Article
High-Temperature Challenges: Electrochemical Investigations into Molten Salt Corrosion Mechanisms
by Fuzhen Yu, John R. Nicholls, Adrianus Indrat Aria and Adnan U. Syed
Crystals 2026, 16(3), 200; https://doi.org/10.3390/cryst16030200 - 15 Mar 2026
Cited by 1 | Viewed by 760
Abstract
Thermal energy storage (TES) systems are widely employed in concentrated solar power (CSP) applications as a means of storing and dispatching energy. Typical thermal fluids used in TES systems include molten salts, such as solar salt (a KNO3–NaNO3 eutectic), as [...] Read more.
Thermal energy storage (TES) systems are widely employed in concentrated solar power (CSP) applications as a means of storing and dispatching energy. Typical thermal fluids used in TES systems include molten salts, such as solar salt (a KNO3–NaNO3 eutectic), as well as other inorganic salts currently under consideration. While these molten nitrate, chloride, sulfate, and carbonate salts offer favourable thermal properties, they can induce significant corrosion of metallic containment materials, leading to reduced system efficiency and component lifetime. Despite extensive post-exposure studies, in situ electrochemical understanding of corrosion mechanisms in molten solar salt remains limited, particularly for emerging alloys such as FeCrAl. In this study, the in situ corrosion behaviour of structural alloys in molten solar salt was investigated using electrochemical impedance spectroscopy (EIS). Complementary post-exposure characterization was performed using destructive techniques, including scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), to assess microstructural and chemical changes. The materials evaluated were stainless steel SS316 and comparatively underexplored Kanthal FeCrAl alloys, exposed to molten solar salt (40 wt% KNO3–60 wt% NaNO3) at 545 °C. The electrochemical and microstructural analyses indicate that FeCrAl exhibits superior corrosion resistance associated with the formation of a more stable and protective oxide scale, compared to SS316 under the investigated conditions. This study provides new electrochemical evidence supporting the suitability of FeCrAl alloys for TES applications, while also indicating that SS316 may develop improved corrosion resistance over extended exposure durations, highlighting the importance of long-term performance assessment. Full article
(This article belongs to the Special Issue Alloy Materials Degradation and Microstructural Study)
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20 pages, 2694 KB  
Article
Formability of AA7021-T4 Sheet Alloy Under Changing Strain Path Conditions: Experiments and Crystal Plasticity Modeling
by Md. Zahidul Sarkar, Joshua Lim, Sarah Sanderson, David T. Fullwood, Marko Knecevic and Michael P. Miles
Crystals 2026, 16(3), 199; https://doi.org/10.3390/cryst16030199 - 15 Mar 2026
Viewed by 474
Abstract
The formability of AA7021-T4 sheets under changing strain paths was investigated via a novel crystal plasticity model and associated experimentation. The motivation was to advance simulation tools for process design of limited-ductility 7xxx alloys, with important applications in the automotive industry. Pre-strains were [...] Read more.
The formability of AA7021-T4 sheets under changing strain paths was investigated via a novel crystal plasticity model and associated experimentation. The motivation was to advance simulation tools for process design of limited-ductility 7xxx alloys, with important applications in the automotive industry. Pre-strains were applied in biaxial and plane-strain tension using Marciniak tooling, followed by uniaxial tensile testing to failure. Strain measurements were obtained by digital image correlation, while dislocation structures were characterized using high-resolution EBSD. A strain-gradient elasto-plastic self-consistent (SG-EPSC) model incorporating dislocation density-based hardening and backstress from geometrically necessary dislocations (GNDs) was employed to predict the stress–strain response and dislocation evolution. Results showed that pre-strains normalized by forming limit diagram (FLD) criteria produced comparable residual uniaxial tensile ductility, regardless of whether biaxial or plane-strain tension was applied, despite differences in absolute pre-strain levels. Both experiments and simulations revealed that GND density correlated with remaining ductility better than simple strain magnitude values. These findings indicate that AA7021-T4 retains greater formability under multiaxial strain path changes than expected from FLD-based considerations. The combined experimental–modeling approach demonstrates the value of incorporating microstructure-based variables, such as GNDs, into forming assessments of high-strength aluminum alloys, with implications for their potential use in automotive lightweighting development. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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11 pages, 2677 KB  
Article
Large-Size Barium Nitrate Crystal Growth and Large-Energy, High-Efficiency Raman Frequency Conversion to Yellow–Orange Waveband
by Xiaojing Lin, Hongkai Ren, Pingzhang Yu, Guowei Liu, Zhengping Wang, Xun Sun and Xinguang Xu
Crystals 2026, 16(3), 198; https://doi.org/10.3390/cryst16030198 - 13 Mar 2026
Viewed by 519
Abstract
Stimulated Raman scattering (SRS) with Raman crystals is widely recognized as an effective technical approach for achieving high-efficiency lasers at specific wavelengths. However, due to crystal size limitations, it is challenging to generate large-energy Raman lasers while simultaneously considering the laser damage threshold [...] Read more.
Stimulated Raman scattering (SRS) with Raman crystals is widely recognized as an effective technical approach for achieving high-efficiency lasers at specific wavelengths. However, due to crystal size limitations, it is challenging to generate large-energy Raman lasers while simultaneously considering the laser damage threshold of optical components. To overcome this limitation, in this paper we describe the successful fabrication of a large-aperture barium nitrate Raman gain medium using the directional template growth technique. Employing this large-aperture Raman medium and a 532 nm pulse laser as the excitation source, a large-energy, high-efficiency yellow–orange waveband laser system was constructed. When injected with 886.7 mJ pump energy at 532 nm, the Raman laser achieved a maximum output energy of 556.2 mJ, corresponding to an optical-to-optical conversion efficiency of 62.7%. This represents a significant advancement in single-pulse energy for barium nitrate Raman lasers. Large-energy yellow–orange wavelength lasers have applications in the clinical treatment of skin diseases and microfluidic chip manufacturing. Full article
(This article belongs to the Section Crystal Engineering)
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21 pages, 10585 KB  
Article
Effect of Sulfur on Hot Corrosion Behavior of Nickel-Based Superalloys at 900 °C
by Dongxing Yue, Wenhao Feng, Yi Shen, Qian Gao, Ruijuan Pan, Xiaolong Su, Xiaoyong Zhang and Jianxiu Chang
Crystals 2026, 16(3), 197; https://doi.org/10.3390/cryst16030197 - 13 Mar 2026
Viewed by 774
Abstract
Nickel-based superalloys are extensively used in fabricating high-temperature gas turbine components, owing to their superior high-temperature strength, excellent structural stability, and remarkable hot corrosion resistance. The influence of impurity sulfur content on their hot corrosion performance is a core scientific issue in hot-end [...] Read more.
Nickel-based superalloys are extensively used in fabricating high-temperature gas turbine components, owing to their superior high-temperature strength, excellent structural stability, and remarkable hot corrosion resistance. The influence of impurity sulfur content on their hot corrosion performance is a core scientific issue in hot-end component compositional design and smelting. This study investigated chromium (Cr)-rich nickel-based superalloys with sulfur (S) contents of 3 ppm, 16 ppm, and 42 ppm via XRD, SEM, and an EPMA, focusing on their hot corrosion behavior under a 100% Na2SO4 deposit at 900 °C. The results indicated that their hot corrosion products were basically identical, forming a Cr-dominated outer oxide layer rich in Ti, Co, and Ni, an Al2O3-based inner corrosion zone, and a CrSx-dominated sulfide layer. With increasing sulfur content, the outer layer thickness decreased from approximately 30 μm to less than 20 μm, pores in the outer oxide layer increased in quantity and size, and internal sulfides and nitrides accumulated. The average depth of spallation increased from 55 μm for the S3 alloy to 80 μm for the S16 alloy, with the S42 alloy showing even more extensive spallation. The alloy’s hot corrosion performance deteriorated notably with increasing S content. The mechanism of sulfur’s effect on hot corrosion behavior is that sulfur in the alloy segregates at oxide film defects, enhancing defect stability and increasing their quantity and size. These defects serve as rapid diffusion channels for corrosive media, thereby accelerating the alloy’s hot corrosion rate. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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15 pages, 2046 KB  
Article
Structure Analysis and Luminescence Properties of Octaethyl(pyrene-tetrakis(biphenyl))tetrakis(phosphonate)
by Aysenur Limon, Marcus N. A. Fetzer and Christoph Janiak
Crystals 2026, 16(3), 196; https://doi.org/10.3390/cryst16030196 - 13 Mar 2026
Viewed by 537
Abstract
We present a modular building block strategy for synthesizing phosphonated polyaromatic systems as an alternative to the conventional late-stage phosphonation of prefabricated aromatic scaffolds, which often requires harsh conditions and has limited tolerance for functional groups. A monophosphonated biphenyl building block was obtained [...] Read more.
We present a modular building block strategy for synthesizing phosphonated polyaromatic systems as an alternative to the conventional late-stage phosphonation of prefabricated aromatic scaffolds, which often requires harsh conditions and has limited tolerance for functional groups. A monophosphonated biphenyl building block was obtained via nickel-catalyzed phosphonation of dibromobiphenyl at 170 °C for three hours. This synthesis is more economical and milder than typical high-temperature palladium systems. In parallel, a borated pyrene derivative was prepared by Suzuki–Miyaura borylation. The final palladium-catalyzed Suzuki cross-coupling reaction produced the target compound, octaethyl(pyrene-tetrakis(biphenyl))tetrakis(phosphonate), Et8-PyTPPE. Single-crystal X-ray diffraction reveals a centrosymmetric molecule that crystallizes in the triclinic space group P–1, with the inversion center located at the central C–C bond of the pyrene core. The pyrene unit is essentially planar, while the biphenylphosphonate arms are highly twisted relative to the core and to each other. The crystal packing is dominated by weak intermolecular interactions, and no significant π–π stacking is observed. Hirshfeld surface analysis shows that H···H (60.5%) and C···H (22.5%) contacts predominate, while O···H interactions (14.4%) with phosphoryl oxygen atoms represent the most relevant directed contacts. From photophysical investigations, Et8-PyTPPE exhibits blue fluorescence (λem. = 452 nm) in solution and aggregation-induced red-shifted emission with nanosecond lifetimes in the solid state, confirming purely fluorescent behavior. Full article
(This article belongs to the Special Issue Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds (3rd Edition))
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10 pages, 1959 KB  
Article
In Situ Synchrotron Radiation Computed Tomography Study on Fatigue Damage Evolution of Additively Manufactured Ti-6Al-4V Alloy
by Hui Wang, Guangcheng Fan and Yu Xiao
Crystals 2026, 16(3), 195; https://doi.org/10.3390/cryst16030195 - 11 Mar 2026
Viewed by 567
Abstract
Additive manufacturing (AM) of Ti-6Al-4V alloy is widely used in aerospace and medical fields due to its excellent strength and corrosion resistance. However, the microstructural heterogeneity induced by the AM process often results in fatigue properties inferior to those of their forged counterparts. [...] Read more.
Additive manufacturing (AM) of Ti-6Al-4V alloy is widely used in aerospace and medical fields due to its excellent strength and corrosion resistance. However, the microstructural heterogeneity induced by the AM process often results in fatigue properties inferior to those of their forged counterparts. Synchrotron Radiation Computed Tomography (SR-CT) was employed to conduct an in situ three-dimensional investigation of fatigue damage evolution in Ti-6Al-4V alloy fabricated via laser powder bed fusion (LPBF). Experimental results revealed phenomena of crack bridging and deflection, accompanied by the consistent presence of local high-density zones (LHDZs) throughout the fatigue damage progression. Combined with quantitative analysis of crack propagation rates, the influence of LHDZs on fatigue damage evolution was analyzed, and the relationship between AM processes, LHDZs, and fatigue damage was discussed. The results indicate that the basket-weave α-phase microstructure in Ti-6Al-4V prepared by LPBF exhibits a high correlation with the distribution of LHDZs, and the orientation of LHDZs aligns with the crack propagation direction. By adjusting process parameters such as cooling rate and temperature gradient, the formation of LHDZs can be modified, thereby influencing the fatigue properties of the material. This provides theoretical support for achieving process optimization of the fatigue properties of Ti-6Al-4V alloy prepared via LPBF. Full article
(This article belongs to the Special Issue Applications of Additive Manufacturing and Numerical Simulation in High-Performance Metallic Materials)
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9 pages, 1137 KB  
Article
Diffusional Solid-State Transformation for the Formation of Copper Oxide Nanowires During the Thermal Oxidation Process
by Caiting Ji, Jingjing Liu, Xiaoting Liu, Yuexia Li and Xiaoxu Bo
Crystals 2026, 16(3), 194; https://doi.org/10.3390/cryst16030194 - 11 Mar 2026
Viewed by 430
Abstract
The solid-state transformation theory has been used to describe the formation of CuO nanowires during the oxidation of Cu metal in air. In order to fill the gaps of the nucleation mechanism of CuO nanowires, a quantitative model has been founded based on [...] Read more.
The solid-state transformation theory has been used to describe the formation of CuO nanowires during the oxidation of Cu metal in air. In order to fill the gaps of the nucleation mechanism of CuO nanowires, a quantitative model has been founded based on the classical nucleation theory, and the results show that the formation of the CuO nanowires is controlled by a solid solution precipitation process under steady-state heterogeneous nucleation circumstances, which will provide beneficial references for the analysis and preparation of metal oxide nanowires of other metal elements. Full article
(This article belongs to the Section Materials for Energy Applications)
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9 pages, 1772 KB  
Article
High-Quality (0001) α-Ga2O3 Film Grown by Mist Chemical Vapor Deposition on (0001) α-Cr2O3 Template
by Kotono Yamada, Shiyu Xiao, Kazuto Murakami, Ryuma Iida, Morimichi Watanabe, Takahiro Tomita and Tomohiro Yamaguchi
Crystals 2026, 16(3), 193; https://doi.org/10.3390/cryst16030193 - 11 Mar 2026
Viewed by 623
Abstract
A (0001) α-Ga2O3 film was grown by the mist chemical vapor deposition method on a (0001) α-Cr2O3 template (100 μm thick α-Cr2O3 layer formed on an α-Al2O3 substrate). Benefiting from the [...] Read more.
A (0001) α-Ga2O3 film was grown by the mist chemical vapor deposition method on a (0001) α-Cr2O3 template (100 μm thick α-Cr2O3 layer formed on an α-Al2O3 substrate). Benefiting from the small a-axis lattice mismatch between α-Ga2O3 and α-Cr2O3, a high-quality α-Ga2O3 film with a small twist distribution, and consequently a low edge dislocation density, was coherently grown on an α-Cr2O3 template. The edge dislocation density of 7 × 107 cm−2, estimated from the full-width at half-maximum value of the X-ray rocking curve (XRC) in X-ray diffraction (XRD), was more than two orders of magnitude lower than that of the film grown on an α-Al2O3 substrate, and was almost consistent with that of the α-Cr2O3 template. The bright-field transmission electron microscopy (TEM) image supports the dislocation density estimated from the XRD measurements. The high-angle annular dark-field scanning TEM and inverse fast Fourier transform images indicate coherent growth, with almost no misfit dislocations generated at the α-Ga2O3/α-Cr2O3 interface. Full article
(This article belongs to the Section Crystal Engineering)
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14 pages, 3516 KB  
Article
Effect of Fe Content on the Microstructure and Properties of 5083 Aluminum Alloy
by Jun Cao, Wenjia Zhao, Jiaxing Li, Hongqun Tang, Xu Zheng, Kezhun He, Qizhong Zhao, Hongchi Yang, Xianye Lu, Shengyuan Lei and Chunhua Wei
Crystals 2026, 16(3), 192; https://doi.org/10.3390/cryst16030192 - 11 Mar 2026
Cited by 1 | Viewed by 551
Abstract
To address the challenge of controlling Fe impurity content during the recycling of aluminum alloys, this study utilized commercial 5083 aluminum alloy as a matrix to prepare alloy samples with four different Fe contents via smelting. The effects of Fe content on the [...] Read more.
To address the challenge of controlling Fe impurity content during the recycling of aluminum alloys, this study utilized commercial 5083 aluminum alloy as a matrix to prepare alloy samples with four different Fe contents via smelting. The effects of Fe content on the microstructure, mechanical properties, and corrosion resistance of the as-cast 5083 aluminum alloy were systematically investigated. The results indicate that increasing the Fe content induces a significant morphological evolution of the Fe-rich phases, transitioning from compact Chinese-script α-Al(Fe,Mn)Si phases at low Fe levels to coarse needle-like β-AlFeSi phases. Concurrently, both the quantity and size of the second phases increase significantly. Mechanical testing reveals that the hardness of the alloy gradually rises from 67 HV to 72 HV due to second-phase strengthening. The tensile strength shows a trend of initially increasing and then decreasing, peaking at 0.45 wt.% Fe; however, excessive Fe leads to the formation of needle-like phases that cause stress concentration, resulting in a decline in tensile strength. The elongation decreases gradually with increasing Fe content, with a maximum reduction of 19.7%. Electrochemical tests show that higher Fe content increases the self-corrosion current density and decreases the capacitive loop radius, indicating a significant degradation in the alloy’s corrosion resistance. This work provides an experimental basis for the tolerance control of Fe impurities and the performance optimization of recycled 5083 aluminum alloys. Full article
(This article belongs to the Special Issue Design, Development and Processing of Aluminium Alloys and Their Composite Materials)
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10 pages, 4026 KB  
Article
Effect of Heating Temperatures During Thermal Processes on the Electrical Properties of Cast Multi-Crystalline Silicon
by Panbing Zhou, Zhiqiang Dong, Nian Yang and Lang Zhou
Crystals 2026, 16(3), 191; https://doi.org/10.3390/cryst16030191 - 11 Mar 2026
Viewed by 401
Abstract
Photoluminescence (PL) imaging techniques combined with a minority carrier lifetime measurement system were utilized to investigate the effects of heating temperature on the interstitial iron (Fei) concentration, the recombination activity of structural defects, and the minority carrier lifetime in cast multicrystalline [...] Read more.
Photoluminescence (PL) imaging techniques combined with a minority carrier lifetime measurement system were utilized to investigate the effects of heating temperature on the interstitial iron (Fei) concentration, the recombination activity of structural defects, and the minority carrier lifetime in cast multicrystalline silicon (mc-Si). The results indicate that heating mc-Si wafers to 800 °C followed by natural cooling led to a 21.4% increase in Fei concentration, a 121% increase in recombination-active dislocations, a 142% increase in recombination-active grain boundaries, a 158% rise in the “dark area percentage,” and a 46.6% decrease in minority carrier lifetime. When the heating temperature was increased to 1000 °C followed by natural cooling, the Fei concentration rose by a factor of 11.87, and the “dark area percentage” increased by 8668%, suggesting widespread metal impurity—particularly iron contamination across the entire wafer, which resulted in an extremely low minority carrier lifetime of only 0.224 μs. Full article
(This article belongs to the Section Materials for Energy Applications)
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11 pages, 1936 KB  
Article
Effect of Lapping Parameters on Material Removal Rate and Surface Roughness of GaN (0001) Plane
by Hao Zhou, Yongliang Shao, Baoguo Zhang, Haixiao Hu, Yongzhong Wu and Xiaopeng Hao
Crystals 2026, 16(3), 190; https://doi.org/10.3390/cryst16030190 - 11 Mar 2026
Viewed by 516
Abstract
As a critical pretreatment process for chemical and mechanical polishing (CMP), the lapping roughness of gallium nitride (GaN) crystals directly influences the outcome of subsequent polishing and the reliability of final devices. This study systematically investigates the key factors affecting the lapping performance [...] Read more.
As a critical pretreatment process for chemical and mechanical polishing (CMP), the lapping roughness of gallium nitride (GaN) crystals directly influences the outcome of subsequent polishing and the reliability of final devices. This study systematically investigates the key factors affecting the lapping performance of GaN single crystals, focusing on abrasive type, particle size, and spindle speed, and elucidates their mechanisms in regulating material removal rate (MRR) and surface roughness. Using a micro-thickness gauge and controlled variable method, the material removal depth of the (0001) plane of GaN was accurately measured. The results show that the MRR increases with the increase in abrasive particle size within a certain range, albeit at the cost of increased surface roughness. Meanwhile, the spindle speed and MRR exhibit a positive correlation under specific conditions. Considering these lapping parameters, a balance between high MRR and controlled roughness can be achieved, providing a technical foundation for efficient and precise lapping of GaN crystals and facilitating the fabrication of GaN-based devices. Full article
(This article belongs to the Special Issue Advances in the Growth and Application of Nitride Crystals)
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16 pages, 2858 KB  
Article
Theoretical and Experimental Exploration of Au-Pt Anode for Efficient Ascorbate Oxidation in Sustainable Fuel Cells
by Mostafizur Rahaman, Mohebul Ahsan, Md. Fahamidul Islam, Md. Asaduzzaman, Kazi Hamidur Rashid, Mohammad Afsar Uddin and Mohammad A. Hasnat
Crystals 2026, 16(3), 189; https://doi.org/10.3390/cryst16030189 - 11 Mar 2026
Viewed by 1621
Abstract
The development of efficient and non-toxic fuels for direct liquid fuel cells has highlighted ascorbic acid (AA) as a sustainable energy source. This study presents a combined theoretical and experimental investigation of ascorbate oxidation on an Au-Pt electrode in alkaline medium. Density functional [...] Read more.
The development of efficient and non-toxic fuels for direct liquid fuel cells has highlighted ascorbic acid (AA) as a sustainable energy source. This study presents a combined theoretical and experimental investigation of ascorbate oxidation on an Au-Pt electrode in alkaline medium. Density functional theory (DFT) calculations reveal that Au deposition on Pt creates a more homogeneous and active surface, significantly enhancing the adsorption energy of ascorbate (−7.54 eV vs. −5.80 eV on bare Pt). Electrochemically, this translates to a superior performance, where the Au-Pt electrode achieves a 38% reduction in charge-transfer resistance, a higher current density, and a lower Tafel slope of 77 mV dec−1, indicating accelerated kinetics. The electrode also retains its activity over 1000 cycles, confirming exceptional durability. This synergistic combination of theoretical and experimental results establishes Au-Pt as a premier catalyst for sustainable ascorbate-based energy conversion. Full article
(This article belongs to the Special Issue Research on Electrolytes and Energy Storage Materials (2nd Edition))
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11 pages, 3320 KB  
Article
Research on the Corrosion Behavior of Zn-2Al Filler Metals
by Yue Zhao, Xuewen Wang, Shirui Guo, Lujun Cui, Yinghao Cui, Yuanxun Shen, Quanbin Lu, Xiaolei Li and Yongqian Chen
Crystals 2026, 16(3), 188; https://doi.org/10.3390/cryst16030188 - 10 Mar 2026
Viewed by 425
Abstract
The performance of flux-cored Zn-Al filler metal is susceptible to corrosion-induced degradation, thereby impairing its brazability. In this study, flux-cored Zn-2Al filler metals are prepared, and the salt spray test is subsequently carried out on the prepared filler metals. Scanning transmission electron microscope [...] Read more.
The performance of flux-cored Zn-Al filler metal is susceptible to corrosion-induced degradation, thereby impairing its brazability. In this study, flux-cored Zn-2Al filler metals are prepared, and the salt spray test is subsequently carried out on the prepared filler metals. Scanning transmission electron microscope is used to identify the phases in filler metals. An electrochemical workstation was employed to test the electrochemical performance of the filler metals. The corrosion pathways and evolution patterns of filler metals are analyzed. The findings demonstrate that the corrosion type of the filler metals is electrochemical corrosion, characterized primarily by the corrosion modes of pitting corrosion and intergranular corrosion. The cathode is the α-Al phase, which undergoes an oxygen-absorption corrosion reaction, while the anode is the η-Zn phase, which experiences corrosion and subsequent dissolution. The continuously distributed α-Al phase bands and discontinuously distributed large-sized rod-like α-Al phases accelerate the corrosion rate, and the corrosion propagation rate along the extrusion direction is higher than that in the radially inward direction. After 15 days of salt spray corrosion, the tensile strength of filler metals decreases by 16.2%, and the elongation rate decreases to 3.73%. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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20 pages, 8212 KB  
Article
Study on the Static Recrystallization Behavior of Ti-2Al-2.5Zr Alloy Tubes
by Wenzhen Fan, Jun Wu, Qi Xu and Xuefei Huang
Crystals 2026, 16(3), 187; https://doi.org/10.3390/cryst16030187 - 10 Mar 2026
Viewed by 577
Abstract
This study systematically investigated the static recrystallization behavior and microstructural evolution of cold-rolled Ti-2Al-2.5Zr alloy tubes subjected to isothermal annealing at 650–800 °C. Electron backscatter diffraction (EBSD), optical microscopy, and microhardness testing were used to analyze recrystallization kinetics, grain size, grain boundary character, [...] Read more.
This study systematically investigated the static recrystallization behavior and microstructural evolution of cold-rolled Ti-2Al-2.5Zr alloy tubes subjected to isothermal annealing at 650–800 °C. Electron backscatter diffraction (EBSD), optical microscopy, and microhardness testing were used to analyze recrystallization kinetics, grain size, grain boundary character, texture evolution, and strain energy release under different annealing temperatures and times. The results show that with increasing annealing temperature, the recrystallization incubation time is significantly shortened and the recrystallization rate increases nonlinearly; the times required for full recrystallization at 650, 700, 750, and 800 °C are 480 min, 25 min, 20 min, and 15 min, respectively. Compared with the other annealing temperatures, annealing at 700 °C yields finer, more uniform equiaxed grains and lower texture intensity, while at higher temperatures, recrystallization and recovery proceed too rapidly, which is unfavorable for fine control of the microstructure. After completion of recrystallization, the alloy microhardness stabilizes at approximately 200 HV. Based on the Avrami kinetics model, the recrystallization activation energy of the Ti-2Al-2.5Zr alloy tubes was calculated to be approximately 303.9 kJ/mol, providing a theoretical basis for optimizing the annealing process. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
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24 pages, 7190 KB  
Article
Effects of Loading Direction on Mechanical Behavior of Core–Shell Cu-Al Nanoparticles Under Uniform Compressive Loading-Molecular Dynamics Study
by Phillip Tomich, Michael Zawadzki and Iman Salehinia
Crystals 2026, 16(3), 186; https://doi.org/10.3390/cryst16030186 - 10 Mar 2026
Viewed by 585
Abstract
The mechanical behavior of metallic core–shell nanoparticles is critical for their use as reinforcement particles and additive manufacturing feedstocks, yet their deformation mechanisms remain incompletely understood. This study employs molecular dynamics simulations to investigate the compressive response of a Cu-core/Al-shell nanoparticle and compares [...] Read more.
The mechanical behavior of metallic core–shell nanoparticles is critical for their use as reinforcement particles and additive manufacturing feedstocks, yet their deformation mechanisms remain incompletely understood. This study employs molecular dynamics simulations to investigate the compressive response of a Cu-core/Al-shell nanoparticle and compares it with solid Cu, solid Al, and a hollow Al shell of the same size under uniaxial loading along ⟨100⟩, ⟨110⟩, ⟨111⟩, and ⟨112⟩ directions. The single-material nanoparticles show strong anisotropy: solid Cu exhibits orientation-dependent transitions from dislocation slip to deformation twinning, while introducing a void to form a hollow Al shell reduces stiffness and strength, confines plasticity to the shell wall, and suppresses extended load-bearing twins. The Cu–Al core–shell nanoparticle combines these behaviors in an orientation-dependent manner. Under ⟨110⟩ and ⟨112⟩ loading, deformation is largely shell-dominated, whereas ⟨100⟩ and ⟨111⟩ loading more strongly activates the Cu core. Mechanistically, ⟨100⟩ is characterized by Shockley partial activity and junction/lock formation in the Al shell coupled with twinning in the Cu core; ⟨110⟩ shows primarily shell partials with limited core involvement; ⟨111⟩ promotes partial-dislocation activity in both shell and core; and ⟨112⟩ produces localized, twin-dominated bands in the Al shell with shell-thickness-dependent twin extension into the Cu core. These trends are rationalized using Schmid factor considerations for 111⟨110⟩ slip and 111⟨112⟩ partial/twinning shear, together with the effects of faceted free surfaces and the Cu–Al interface. The core–shell geometry enables two concurrent interface-mediated pathways, i.e., (i) stress transfer and reduced cross-interface transmission and (ii) circumferential bypass within the shell, which together yield only slight flow-stress increases over solid Al while markedly reducing stress serrations compared with both solid Cu and solid Al. Across all orientations, the core–shell structures also exhibit delayed yielding (higher yield strain) relative to solid Cu, indicating enhanced ductility. The results provide an atomistic basis for designing Cu–Al core–shell nanoparticles for robust particle-based processing and additive manufacturing feedstock, and for informing multiscale models with mechanism-resolved, orientation-dependent inputs. Full article
(This article belongs to the Special Issue Structure, Properties, and Applications of Nanomaterials and Thin Films)
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