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Formation of a Guest-Accessible Cavity in a Cyclic Tetranuclear Fe(III) Macrocycle: Structural Control via μ-Oxo Bridging
Inhomogeneities Generating Mechanisms in Membranes
Phase Transformations in Rapidly Solidified Al-Cu-Li-Mg-Sc-Zr Alloy During Model Homogenization Studied by In Situ STEM
Reanalysis of Raman Spectra of Singly and Doubly Charged BEDT-TTF Dimers in the Solid State
Multi-Phase Evolution and Surface Degradation Kinetics of a Non-Equiatomic (FeCoNiCr)₈₅Ga₁₅ High Entropy Alloy: The Role of Low-Temperature Thermal Activation

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, Ei Compendex, 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 12.9 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the first half of 2026).
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.
Journal Cluster of Metallurgy and Corrosion Science: Metals, Coatings, Crystals, Corrosion and Materials Degradation, Alloys, Iron and Welding.

Impact Factor: 2.9 (2025); 5-Year Impact Factor: 2.8 (2025)

Imprint Information Journal Flyer Open Access ISSN: 2073-4352

Latest Articles

21 pages, 9359 KB

Open AccessArticle

Effect of Trace Phosphorus Addition on the Solidification Behavior and Local Mechanical Response of β-Sn Alloys

by Yupeng Wang, Zhuangchao Zhan, Huilin Zhang, Hongbo Qin, Jiaqiang Huang, Wangyun Li, Caihang Liang, Lili Wang, Chengxu Lin and Mingzhen Hu

Crystals 2026, 16(8), 498; https://doi.org/10.3390/cryst16080498 - 29 Jul 2026

To investigate the effects of trace phosphorus (P) addition on the solidification behavior, microstructure, and local mechanical response of β-Sn alloys, Sn–P alloys containing 0.02, 0.05, and 0.08 wt.% P were prepared. Phase constitution, solidification characteristics, and nanomechanical properties were characterized by X-ray [...] Read more.

To investigate the effects of trace phosphorus (P) addition on the solidification behavior, microstructure, and local mechanical response of β-Sn alloys, Sn–P alloys containing 0.02, 0.05, and 0.08 wt.% P were prepared. Phase constitution, solidification characteristics, and nanomechanical properties were characterized by X-ray diffraction, thermogravimetry–differential scanning calorimetry, and nanoindentation, respectively. Electron backscatter diffraction was additionally conducted on representative pure Sn and Sn–P0.08 samples to qualitatively compare the endpoint microstructures. All alloys were primarily composed of β-Sn, while localized P-rich secondary regions in Sn–P0.08 were indexed as Sn₄P₃. Trace P promoted heterogeneous nucleation and markedly modified solidification, increasing the solidification peak temperature by approximately 20–22 °C and reducing the undercooling from 39.83 °C to 17.50–20.33 °C. Relative to pure Sn, Sn–P0.08 exhibited more grain regions and grain boundaries, together with pronounced dendritic and locally refined features, indicating modified β-Sn nucleation and growth. Young’s modulus and hardness of Sn–P0.08 reached 29.86 GPa and 0.232 GPa, respectively. Inverse nanoindentation analysis revealed increased representative stress, strain-hardening exponent, and strength coefficient. Fracture-energy analysis showed superior crack-growth energy dissipation for Sn–P0.02, whereas Sn–P0.08 exhibited greater resistance to plastic deformation. Full article

(This article belongs to the Section Crystalline Metals and Alloys)

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10 pages, 2737 KB

Open AccessArticle

Electrically Activating and Switching the Magneto-Optic Faraday Effect in 2D Antiferromagnets

by Liyuan Zhang, Chen Liang and Chuanhui Gong

Crystals 2026, 16(8), 497; https://doi.org/10.3390/cryst16080497 - 29 Jul 2026

Two-dimensional (2D) antiferromagnets are highly promising for next-generation spintronics due to their ultrafast dynamics and robustness against stray fields; however, their practical application is severely hindered by the vanishing magneto-optic effects restricted by strict crystal symmetries. In this work, we propose a universal [...] Read more.

Two-dimensional (2D) antiferromagnets are highly promising for next-generation spintronics due to their ultrafast dynamics and robustness against stray fields; however, their practical application is severely hindered by the vanishing magneto-optic effects restricted by strict crystal symmetries. In this work, we propose a universal physical mechanism to activate and manipulate the magneto-optic Faraday effect in 2D fully compensated bilayer antiferromagnets using an external vertical electric field. By constructing a comprehensive tight-binding model and performing first-principles calculations on bilayer

{VSe}_{2}

, we demonstrate that the applied electric field explicitly breaks the spatial inversion and combined

PT

symmetries. This symmetry breaking lifts the Kramers degeneracy, inducing a pronounced spin splitting that, in conjunction with intrinsic spin–orbit coupling, generates non-vanishing Berry curvature. Consequently, the previously forbidden Faraday rotation angle is activated from zero to a significant non-zero value, and its rotation direction can be deterministically reversed by switching the electric field polarity. Our findings provide profound physical insights into the symmetry-modulated light–matter interactions and pave the way for designing fully electrically controllable, energy-efficient antiferromagnetic opto-spintronic devices. Full article

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18 pages, 2750 KB

Open AccessReview

A Critical Review of Homogenization and Aging Behaviors of Micro-Alloyed 7xxx Al Alloy for Advanced Aerospace Application

by Gurudas Mandal, Rahul Samanta, Sandip Kunar, Amitava Ghatak, Habib Masum, Aman Gupta and Guojun Ma

Crystals 2026, 16(8), 496; https://doi.org/10.3390/cryst16080496 - 29 Jul 2026

In the aircraft industry, with the growing demand for advanced, sustainable structural materials, researchers are increasingly focusing on developing Al-Zn-Mg-Cu alloys, particularly the Al 7075 alloy with micro-alloying elements. However, load and environmental conditions pose problems for the aircraft industry by significantly reducing [...] Read more.

In the aircraft industry, with the growing demand for advanced, sustainable structural materials, researchers are increasingly focusing on developing Al-Zn-Mg-Cu alloys, particularly the Al 7075 alloy with micro-alloying elements. However, load and environmental conditions pose problems for the aircraft industry by significantly reducing fleet service life. Thus, researchers are keen to use micro-alloying elements such as Ni, Ce, Ag, Sn, Ti, and Cd with the Al 7xxx base alloy to achieve enhanced mechanical properties, particularly hardness and tensile strength. Besides micro-alloying, the heat treatment (HT) process and cold working also have a favorable effect on the improvement of the mechanical properties. However, the addition of micro-alloying elements improves those properties more than HT and cold working processes. In this review study, several mechanical properties of the alloy have been comprehensively covered, which helps to establish a comparative analysis between the heat-treated base alloy and heat-treated micro-alloyed Al alloy. The base alloy, after micro-alloying, becomes enriched, with a high formability and workability, high conductivity, and good erosion protection that significantly make these alloys sustainable for the aircraft industry. The impact of dynamic changes accompanying the use of this lightweight alloy, after identifying the sensible necessities for the development of techniques, can effectively change the whole concept of the structural design. Hence, the key emphasis of the present review lies in a better understanding of the correlation between the structure and properties of micro-alloyed Al 7xxx alloy, which heralds a new era for aircraft industries. Full article

(This article belongs to the Special Issue Microstructure, Properties and Characterization of Aluminum Alloys)

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16 pages, 2626 KB

Open AccessFeature PaperArticle

Amorphization-Enabled Direct Z-Scheme CdSe/MoSe_x Heterojunction for Enhanced Photocatalysis

by Lie Tian, Rong Wu, HaiYang Liu, Dong Zhang and Xiangqian Shen

Crystals 2026, 16(8), 495; https://doi.org/10.3390/cryst16080495 - 28 Jul 2026

Organic pollutant degradation demands photocatalysts that couple efficient charge separation with strong redox capability. Direct Z-scheme heterojunction architectures fulfill these requirements and are consequently considered promising candidates. However, the rational design of such systems continues to present a major obstacle. Herein, a CdSe/amorphous [...] Read more.

Organic pollutant degradation demands photocatalysts that couple efficient charge separation with strong redox capability. Direct Z-scheme heterojunction architectures fulfill these requirements and are consequently considered promising candidates. However, the rational design of such systems continues to present a major obstacle. Herein, a CdSe/amorphous MoSe_x (CdSe/a-MoSe_x) direct Z-scheme heterojunction was successfully synthesized via a simple solid-state grinding and low-temperature hydrothermal method. Within 120 min under visible-light irradiation, methylene blue (MB, 40 mg/L) was degraded to 97.3% efficiency by the CdSe/a-MoSe_x heterojunction, whose photocatalytic activity markedly exceeded that of pristine CdSe and a-MoSe_x. Intimate interfacial contact between CdSe and a-MoSe_x enables photogenerated carriers to separate and migrate more efficiently, underpinning the observed performance enhancement. Moreover, the suitable band alignment derived from valence-band (VB) XPS and Mott-Schottky measurements supports the formation of a direct Z-scheme charge-transfer pathway. The Z-scheme mechanism effectively inhibits electron-hole recombination while maintaining the robust oxidation and reduction capabilities of the photogenerated carriers. This study offers a straightforward approach for fabricating CdSe/a-MoSe_x direct Z-scheme heterojunctions for the efficient photocatalytic degradation of organic pollutants. Full article

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46 pages, 52229 KB

Open AccessArticle

Hard-Particle Surface Stabilization and Data-Driven Wear Prediction in TiB₂-Reinforced Heat-Polymerized PMMA Denture Base Composites

by Ethem Furkan Hıdır, Ali Sincar, Cevher Kürşat Macit, Samet Tekin and Ukbe Usame Uçar

Crystals 2026, 16(8), 494; https://doi.org/10.3390/cryst16080494 - 28 Jul 2026

Poly(methyl methacrylate) (PMMA) remains a clinically important denture base polymer because of its favorable processability, aesthetics, repairability and long-term prosthodontic use; however, its limited surface hardness and susceptibility to sliding-induced degradation constrain surface durability. This study establishes the structure–chemistry–microstructure–tribology relationships and composition-window predictive [...] Read more.

Poly(methyl methacrylate) (PMMA) remains a clinically important denture base polymer because of its favorable processability, aesthetics, repairability and long-term prosthodontic use; however, its limited surface hardness and susceptibility to sliding-induced degradation constrain surface durability. This study establishes the structure–chemistry–microstructure–tribology relationships and composition-window predictive behavior of heat-polymerized PMMA reinforced with titanium diboride (TiB₂). PMMA/TiB₂ composites containing 1, 3 and 5 wt.% TiB₂ were prepared and compared with unreinforced PMMA. X-ray diffraction confirmed preservation of the broad amorphous/semi-amorphous PMMA response, while TiB₂-related crystalline features became increasingly detectable with reinforcement content. ATR-FTIR showed retention of the characteristic C–H, ester C=O and C–O/C–O–C vibrations. SEM/EDS demonstrated progressively greater particle-related surface contrast and local Ti/B-associated elemental signatures. Vickers microhardness increased from 20.0 ± 0.7 to 35.0 ± 1.39 HV0.03, corresponding to a 75.0% improvement at 5 wt.% TiB₂. After 1000 m of dry sliding, total mass loss decreased from 32.4 ± 0.5 to 14.9 ± 0.4 mg (54.0% reduction), overall coefficient of friction decreased from 0.58 to 0.35, and representative wear-track width decreased from 481.4 to 101.8 µm. A parsimonious distance–composition interaction model retained strong grouped leave-one-composition-out performance for cumulative wear (R² = 0.9622; RMSE = 1.53 mg), while a linear composition model provided the most robust hardness prediction (R² = 0.9317; RMSE = 1.50 HV0.03). More complex nonlinear models did not improve prediction for held-out compositions. Within the investigated 0–5 wt.% window, 5 wt.% TiB₂ provided the most effective combination of matrix preservation, surface hardening, wear suppression and frictional stabilization. Full article

(This article belongs to the Special Issue Crystals: 15th Anniversary)

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12 pages, 6079 KB

Open AccessArticle

Optimized Brazing Performance of Amorphized Cu-P-Sn-Ni Fillers for Copper Joining

by Shenggang Wang, Chang Yu, Lin Yang and Xiaohong Yang

Crystals 2026, 16(8), 493; https://doi.org/10.3390/cryst16080493 - 28 Jul 2026

In this study, amorphous Cu₈₆P_7.5Sn_4.5Ni₂(wt.%) fillers were prepared using the melt spinning method with different rolling speeds. The wetting performance of these fillers on copper was assessed under different temperatures and holding times. The results [...] Read more.

In this study, amorphous Cu₈₆P_7.5Sn_4.5Ni₂(wt.%) fillers were prepared using the melt spinning method with different rolling speeds. The wetting performance of these fillers on copper was assessed under different temperatures and holding times. The results indicated that the fillers obtained through the melt spinning technique exhibited lower melting temperatures than the as-cast filler. When processed at a rolling speed of 20 m/s, the amorphization of the filler was not sufficient. The higher rolling speed promoted the formation of the amorphous structure. The amorphous filler produced at 30 m/s exhibited the narrowest melting range and the lowest liquidus temperature (622 °C), which is approximately 100 °C lower than that of the as-cast filler (725 °C). Furthermore, the amorphous fillers also exhibited better wettability toward copper under the same conditions. Notably, the amorphous filler fabricated at 30 m/s demonstrated superior wettability at 750 °C for 90 s. Owing to the optimal wettability of the amorphized filler toward copper and the lower liquid temperature, the brazed copper joint achieved a shear strength of 223.2 MPa. The fracture of the four joints occurred in the base metal. In this study, we explored the brazing performance of amorphized Cu-based fillers, facilitating the solid bonding of copper at lower brazing temperatures. Full article

(This article belongs to the Section Crystalline Metals and Alloys)

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14 pages, 8762 KB

Open AccessArticle

Third Unique Polymorph of bis(2,9-Dimethyl-1,10-phenanthroline)-Copper(I) tetrafluoroborate, [Cu(dmp)₂](BF₄)

by Kristen Oberle and Daron E. Janzen

Crystals 2026, 16(8), 492; https://doi.org/10.3390/cryst16080492 - 28 Jul 2026

Polymorphic behavior has significant consequences in solid-state properties relevant to functional materials and pharmaceutical applications. This study reports the single-crystal X-ray structure of a new third unique polymorph of the photoluminescent compound [Cu(dmp)₂](BF₄) (dmp = 2,9-dimethyl-1,10-phenanthroline). A detailed analysis [...] Read more.

Polymorphic behavior has significant consequences in solid-state properties relevant to functional materials and pharmaceutical applications. This study reports the single-crystal X-ray structure of a new third unique polymorph of the photoluminescent compound [Cu(dmp)₂](BF₄) (dmp = 2,9-dimethyl-1,10-phenanthroline). A detailed analysis of how this new polymorph compares with the two previously reported polymorphs was carried out including intramolecular metrics (τ⁴, twisting, flattening, rocking measures) and intermolecular differences (π-stacking, Hirshfeld surfaces). The new polymorph reported here has larger twisting and flattening distortions from an idealized tetrahedral geometry and the largest displacement of Cu from one dmp plane than the other polymorphs. This new polymorph also exhibits enhanced π-stacking that leads to more dense packing than previous reported polymorphs. Hirshfeld surface comparisons are consistent with a larger percentage of C…C short contacts and lower percentage of C…H contacts present in this new polymorph. The variability of intra- and intermolecular differences within this family of three polymorphs compared demonstrates the large degree of flexibility of both the coordination sphere and packing, even with the expected rigid planar bis-bidentate dmp binding to copper. As the polymorphs each show unique inter- and intramolecular features, differences in solid-state properties including solid-state photoluminescence are expected. This demonstrates the importance of phase purity in the construction of solid-state device applications. Full article

(This article belongs to the Section Crystal Engineering)

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27 pages, 30944 KB

Open AccessArticle

The Impact of Spin–Orbit Coupling on the Structural, Mechanical, Electronic, and Optical Properties of MCoBi (M = Ti, Zr, Hf) Half-Heusler Compounds: A FP-LAPW Study

by Sara Lazghed, Farida Annane, Akila Boumaza, Hocine Meradji and Sebti Ghemid

Crystals 2026, 16(8), 491; https://doi.org/10.3390/cryst16080491 - 28 Jul 2026

In this work, the structural, mechanical, electronic, and optical properties of the 18-valence-electron half-Heusler compounds MCoBi (M = Ti, Zr, Hf) are investigated using the all-electron full-potential linearized augmented plane wave (FP-LAPW) method. The relativistic effect of spin–orbit coupling (SOC) is systematically incorporated [...] Read more.

In this work, the structural, mechanical, electronic, and optical properties of the 18-valence-electron half-Heusler compounds MCoBi (M = Ti, Zr, Hf) are investigated using the all-electron full-potential linearized augmented plane wave (FP-LAPW) method. The relativistic effect of spin–orbit coupling (SOC) is systematically incorporated and analyzed. Structural optimization confirms the stability of the Type-III phase, with lattice parameters in good agreement with available experimental data. Mechanically, the inclusion of SOC reduces both stiffness and brittleness, indicating a clear softening effect on the material behavior. SOC significantly lifts the degeneracy of the electronic bands, resulting in splitting (Δ_SO) at the valence band maximum of approximately 0.10 eV and 0.12 eV for TiCoBi and ZrCoBi, respectively, which subsequently reduces the band gap; however, HfCoBi exhibits a remarkably weak splitting. The impact of SOC is further evidenced in the optical response across all three compounds. The absorption coefficient reaches high values (>

10^{5} {c m}^{- 1}

) in the visible spectrum. Furthermore, a dramatic reduction in the intensity of plasmon resonance frequencies is observed, with values dropping to approximately 0.10–0.11 for the studied compounds. These findings highlight the potential of these materials for future electronic and optoelectronic device applications. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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24 pages, 24504 KB

Open AccessArticle

Microstructural Evolution and Phase Characterization of a Ni-Based Superalloy Under Laser-Assisted Heat Treatment

by Alotaibi Fawaz Marzouq S, Usman Ali, Atta-Ur-Rehman and Talal Ameen Ali Alhemyari

Crystals 2026, 16(8), 490; https://doi.org/10.3390/cryst16080490 - 28 Jul 2026

This study investigates the microstructural evolution and mechanical behavior of a Ni-based superalloy subjected to combined heat treatment and laser processing. Quantitative analysis of γ′ Ni₃(Al,Ti) and η (Ni₃Ti) phase distributions were performed using SEM-based statistical methods. The results [...] Read more.

This study investigates the microstructural evolution and mechanical behavior of a Ni-based superalloy subjected to combined heat treatment and laser processing. Quantitative analysis of γ′ Ni₃(Al,Ti) and η (Ni₃Ti) phase distributions were performed using SEM-based statistical methods. The results show that γ′ precipitates exhibit a fine and uniform distribution with sizes in the range of ~0.05–0.30 µm and a high number density (n ≈ 2916), whereas the η (

{N i}_{3}

Ti) phase appears as relatively coarse particles (~0.1–0.6 µm) with lower number density (n ≈ 505). Laser treatment promotes redistribution of γ′ precipitates and suppresses η phase formation, resulting in improved microstructural homogeneity. Mechanical characterization reveals that optimal aging (2 h) yields the highest hardness of ~525 HV at 300 °C, while tensile properties show yield strength in the range of ~1000–1150 MPa and ultimate tensile strength of ~1300–1500 MPa. The results demonstrate a strong correlation between γ′ refinement and enhanced mechanical performance. These findings provide a quantitative understanding of phase evolution and establish a microstructure-property relationship for optimizing Ni-based superalloys. Full article

(This article belongs to the Special Issue Performance and Processing of Metal Materials)

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68 pages, 14413 KB

Open AccessReview

Reduced Graphene Oxide (rGO)-Based Hybrid Materials as Cathodes in Aqueous Zinc-Ion Batteries: Recent Progress

by Adamantia Zourou, Afroditi Ntziouni and Konstantinos V. Kordatos

Crystals 2026, 16(8), 489; https://doi.org/10.3390/cryst16080489 - 27 Jul 2026

The growing global energy demand and increasing environmental concerns have created the need for the development of efficient, safe, and sustainable energy storage technologies. While lithium-ion batteries (LIBs) have dominated the energy storage market due to their high energy density and long cycle [...] Read more.

The growing global energy demand and increasing environmental concerns have created the need for the development of efficient, safe, and sustainable energy storage technologies. While lithium-ion batteries (LIBs) have dominated the energy storage market due to their high energy density and long cycle life, concerns regarding lithium resource scarcity, high cost, and safety risks associated with flammable organic electrolytes have motivated research on alternative batteries. In this context, aqueous zinc-ion batteries (AZIBs) have attracted significant attention as a promising next-generation energy storage system because of their inherent safety, resulting from the utilization of non-flammable aqueous electrolytes, and environmental friendliness, as well as natural abundance and low cost of zinc. Nevertheless, they face various challenges, which hinder their practical applications. Among them, the intrinsic limitations of the cathode materials, including their poor electronic conductivity, sluggish reaction kinetics and structural degradation during charge–discharge cycles, are considered particularly significant. Thus, the scientific community has explored various mitigation strategies, including the combination of cathode materials with carbon-based nanomaterials, such as reduced graphene oxide (rGO), with exceptional physicochemical properties. The present critical review discusses the most recent scientific work published in the literature during the last three years, referring to the combination of rGO with conventional cathode materials, such as manganese-based oxides, vanadium-based oxides, Prussian blue analogues, etc., for the development of next-generation AZIBs with superior electrochemical performance, long-term cycling durability, intrinsic safety, and enhanced sustainability. Full article

(This article belongs to the Special Issue Functional Nanomaterials for Electrochemical Sensing and Energy Storage)

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26 pages, 4242 KB

Open AccessArticle

Programmable Electroactive Bending Morphology of Cantilevered Dielectric Liquid Crystal Elastomer Sheets via Tuning Mesogen Alignments

by Hongtao Wang and Yiwei Xu

Crystals 2026, 16(8), 488; https://doi.org/10.3390/cryst16080488 - 27 Jul 2026

The nematic mesogens within dielectric liquid crystal elastomers (DLCEs) rotate in response to external electric fields, thereby driving macroscopic active shape morphing. This work establishes a rigorous theoretical framework to investigate the electro-mechanical bending mechanics of cantilevered DLCE sheets governed by this actuation [...] Read more.

The nematic mesogens within dielectric liquid crystal elastomers (DLCEs) rotate in response to external electric fields, thereby driving macroscopic active shape morphing. This work establishes a rigorous theoretical framework to investigate the electro-mechanical bending mechanics of cantilevered DLCE sheets governed by this actuation mechanism. By theoretically formulating the electromechanical effect as a localized spontaneous strain field, we analytically correlate the stress-free deformation with the local nematic director alignment. We demonstrate that the macroscopic bending morphology of the DLCE sheet can be deterministically programmed by tailoring the principal bending directions via this microscopic director design. Our findings reveal that the synergistic interplay between the tailored spontaneous curvature and cantilever boundary constraints generates a rich variety of three-dimensional configurations, enabling active regulation of both deflection and out-of-plane tilting at the free edge. Furthermore, we explicitly highlight the critical, yet often overlooked, role of spontaneous shear strain, which significantly governs the bending response even within the thin-plate limit. These theoretical insights establish a robust foundation for the structural design of DLCE-based directional soft actuators and flexible devices. Full article

(This article belongs to the Special Issue Research on Liquid Crystal Materials and Optical Devices)

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16 pages, 4715 KB

Open AccessArticle

A Quantum Chemical Study of the Gas-Phase Reaction Pathways in Metal–Organic Chemical Vapor Deposition Growth of InAlN

by Peng Su, Yukang Sun and Lijun Liu

Crystals 2026, 16(8), 487; https://doi.org/10.3390/cryst16080487 - 26 Jul 2026

Based on quantum chemical theory, the gas-phase chemical cross-reaction pathways in metal–organic chemical vapor deposition of InAlN films have been investigated. First, calculations of the oligomerization reactions of Al and In amides were performed to investigate the relative difficulty of generating several dimers [...] Read more.

Based on quantum chemical theory, the gas-phase chemical cross-reaction pathways in metal–organic chemical vapor deposition of InAlN films have been investigated. First, calculations of the oligomerization reactions of Al and In amides were performed to investigate the relative difficulty of generating several dimers and trimers within this system. The elimination reaction pathways were then investigated. The final stable products of the polymers were analyzed from both thermodynamic and kinetic perspectives, and the propensities of the reaction pathways were assessed from the viewpoint of the reaction rates. The results indicated that in the gas-phase reaction pathways of InAlN grown by metal–organic chemical vapor deposition, the equilibrium temperature for the dimerization reactions lies between 960 and 1061 K, and above this temperature range, dimers cannot form. Trimer formation is unlikely during the InAlN growth process. At higher reaction temperatures, the oligomers tend to first undergo intramolecular elimination, losing two CH4 molecules to form intermediate products, which then react with NH3 via intermolecular elimination to yield stable products. At lower reaction temperatures, the tendency is for continuous intermolecular elimination with NH4 to generate stable, methyl-free products. Full article

(This article belongs to the Special Issue Advances and Expansion of Epitaxial Nitride-Based Materials)

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25 pages, 2258 KB

Open AccessReview

Research Progress on the Properties of Micro-Arc Oxidation Coatings on 6061 Aluminum Alloy

by Shenghan Li, Baicheng Liu, Haoran Hong, Hongliang Zhang, Teng Liu and Zhisheng Nong

Crystals 2026, 16(8), 486; https://doi.org/10.3390/cryst16080486 - 25 Jul 2026

This work provides a comprehensive review of the development and current research status of micro-arc oxidation (MAO) coatings on 6061 aluminum alloy. It presents research findings on the enhancement of wear resistance, corrosion resistance, and other functional properties (e.g., hydrophobicity, thermal control performance, [...] Read more.

This work provides a comprehensive review of the development and current research status of micro-arc oxidation (MAO) coatings on 6061 aluminum alloy. It presents research findings on the enhancement of wear resistance, corrosion resistance, and other functional properties (e.g., hydrophobicity, thermal control performance, and electrical insulation) using three main strategies: insitu growth via electrolyte composition modification or electrical parameter adjustment, incorporation of nanoparticles into the electrolyte, and hybrid processes combining MAO with other surface treatment techniques (e.g., pre-/post-treatments). The performance of coatings obtained under different strategies is summarized, and a prospective outlook on future development trends in this field is offered. Full article

(This article belongs to the Special Issue Advances in High-Performance Alloys)

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22 pages, 5432 KB

Open AccessArticle

Compatibility and Interfacial Bonding Mechanism Between Portland Cement and Alkali-Activated Materials in Gradient Cementitious Composites: A Comparative Study of Mixed and Layered Casting Methods

by Baoxuan Dou, Guodong Huang, Zhihao Liu, Fengan Zhang, Qi Lu, Ziyang Wang and Tianle Yang

Crystals 2026, 16(8), 485; https://doi.org/10.3390/cryst16080485 - 25 Jul 2026

An innovative cement and alkali-activated gradient cementitious composite was fabricated via mixed and layered casting methods. The influence of casting method and mix proportion on mechanical performance was systematically investigated, and the compatibility and synergistic mechanisms were characterized by XRD, FT–IR, and SEM. [...] Read more.

An innovative cement and alkali-activated gradient cementitious composite was fabricated via mixed and layered casting methods. The influence of casting method and mix proportion on mechanical performance was systematically investigated, and the compatibility and synergistic mechanisms were characterized by XRD, FT–IR, and SEM. Mixed casting resulted in severe incompatibility, with the compressive strength plummeting to 18.7 MPa, a 66.5% reduction compared to the single-component binders. In contrast, layered casting enabled compatibility and coupling between the gradient layers, imparting a pronounced synergistic strengthening effect. The optimal alkali-activated material-to-cement ratio was 8:2, achieving a compressive strength of 62.7 MPa, which is 12.4% higher than that of the single-component composite. Microstructural analysis revealed that, under layered casting, the alkali-activated component continuously consumed the cement hydration by-product Ca(OH)₂ to form calcium aluminosilicate hydrate (C-A-S-H) gel, generating a synergistic reinforcement in the interfacial region and enhancing the overall performance of the composite. Full article

(This article belongs to the Section Hybrid and Composite Crystalline Materials)

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11 pages, 593 KB

Open AccessArticle

Where Do Crystal Graph Networks Fail? A Space-Group-Resolved Error Analysis of Band Gap Prediction with a Simple Edge-Aware GNN: Crystal-X

by Shehroz A. Shoaib and Burhan K. SaifAddin

Crystals 2026, 16(8), 484; https://doi.org/10.3390/cryst16080484 - 24 Jul 2026

Graph neural networks (GNNs) for crystal property prediction are typically evaluated by a single aggregate error, which can mask where, and for which classes of materials, these models fail. In this study, we present a space-group-, centering-type-, and band gap-resolved error analysis of [...] Read more.

Graph neural networks (GNNs) for crystal property prediction are typically evaluated by a single aggregate error, which can mask where, and for which classes of materials, these models fail. In this study, we present a space-group-, centering-type-, and band gap-resolved error analysis of GNN band gap prediction on the Materials Project dataset. As a channel for this analysis we use Crystal-X, a deliberately simple model: a standard graph convolutional backbone with two minor architectural modifications, an asymmetric edge convolution and a neighbor-feature transformation, that supplement bond information often treated as secondary in node-centric models. Crystal-X is not a state-of-the-art model: it reaches a band gap MAE of 0.256 eV on the MP 2018.6 dataset, behind ALIGNN (0.22 eV) and PotNet (0.20 eV), though ahead of older baselines such as CGCNN (0.39 eV), SchNet (0.415 eV), and MEGNet (0.33 eV) while using only the nine-property CGCNN atomic feature set. Its value here is as a controlled, low-complexity testbed for the error analysis. That analysis reveals systematic patterns that aggregate MAE conceals: errors concentrate in underrepresented band gap ranges and in low-symmetry and non-centrosymmetric space groups; per-group errors for sparsely populated space groups are dominated by sampling noise; and modest, as-yet-unverified gains from edge-aware convolutions appear in monoclinic and non-primitive-centered systems. We argue that this kind of granular, symmetry-resolved evaluation should accompany aggregate benchmarks when assessing crystal GNNs. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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21 pages, 24667 KB

Open AccessArticle

Surface Modification of Monolithic Zirconia Using Sandblasting and Laser Methods

by Ximena Estrada Sotelo, Humberto Alejandro Monreal Romero, Laura Isabel Duarte Chávez, Luis Gerardo Maldonado Muñoz, Manuel Antonio Lujan Aguilar, Guillermo Acosta Barriga, Claudia López Meléndez, Héctor Alfredo López Aguilar, José Guadalupe Chacón-Nava and Caleb Carreño-Gallardo

Crystals 2026, 16(8), 483; https://doi.org/10.3390/cryst16080483 - 24 Jul 2026

In this study, zirconia specimens were subjected to Al₂O₃ airborne-particle abrasion and Er laser irradiation to investigate their effects on surface characteristics. The treated and untreated zirconia surfaces were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), qualitative [...] Read more.

In this study, zirconia specimens were subjected to Al₂O₃ airborne-particle abrasion and Er laser irradiation to investigate their effects on surface characteristics. The treated and untreated zirconia surfaces were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), qualitative elemental analysis by laser-induced breakdown spectroscopy (LIBS), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, XRD analysis, and power spectral density (PSD) analysis. The Er laser-treated group showed the highest mean surface roughness (Sa: 7.763 ± 2.449 µm), compared with the Al₂O₃-treated group (3.640 ± 2.164 μm); however, the differences in Sa among the experimental groups were not statistically significant (Kruskal–Wallis, p = 0.095). Likewise, no statistically significant differences were observed for Sz (one-way ANOVA, p = 0.567). SEM, AFM, and PSD analyses provided complementary information on the morphological and spatial characteristics of the surfaces produced by the different treatments. Under the experimental conditions evaluated, Er laser irradiation produced distinct surface topographic features and a descriptive trend toward higher mean Sa values, but statistical superiority over Al₂O₃ airborne-particle abrasion or the untreated control was not demonstrated. Further studies are required to determine whether these surface modifications translate into functional or clinical benefits. Full article

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24 pages, 8061 KB

Open AccessArticle

Quantitative Evolution of Mineral Crystal Structure in Alkali-Activated Materials Derived from Multi-Source Coal-Based Solid Wastes via XRD Refinement

by Guodong Huang, Baoxuan Dou, Zhihao Liu, Fengan Zhang, Qi Lu, Yan Deng, Yixin Pei and Miao Zhu

Crystals 2026, 16(8), 482; https://doi.org/10.3390/cryst16080482 - 24 Jul 2026

To address the rapid flash setting of NaOH-activated slag and promote high-volume utilization of coal-based solid wastes, this study investigated the synergy of fly ash (FA), coal gangue (CG), and gasification slag (GS) in partially replacing granulated blast furnace slag (GBFS) for NaOH [...] Read more.

To address the rapid flash setting of NaOH-activated slag and promote high-volume utilization of coal-based solid wastes, this study investigated the synergy of fly ash (FA), coal gangue (CG), and gasification slag (GS) in partially replacing granulated blast furnace slag (GBFS) for NaOH activated binders, aiming to mitigate flash setting while preserving mechanical performance. Binary and ternary pastes with up to 90 wt% substitution were evaluated for setting time, fluidity, and compressive strength, supported by quantitative XRD and SEM. The G8F1G1 achieved the optimal balance, extending initial and final setting times from 28 and 32 min to 35 and 43 min, yielding a fluidity of 218 mm, and maintaining a 28-day strength of 48.5 MPa, equivalent to neat GBFS. The FA-GS synergy suppressed crystalline by damping the Ca²⁺ supersaturation peak through FA derived oligomers while providing nucleation sites via fine carbonaceous particles in GS, thereby retaining the amorphous C-A-S-H gel at approximately 77 wt%. This preserved the load-bearing gel network but eliminated early percolating crystalline frameworks, extending workability without strength loss. In contrast, CG acted as an inert diluent, introducing weak interfaces and porosity that severely degraded strength. A critical amorphous threshold near 64 wt% (G6F2G2, amorphous gel) governed the transition to a granular bed. The FA-GS system offers an effective route for high-volume valorization of coal-based solid wastes in sustainable construction materials. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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17 pages, 4386 KB

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Numerical Simulation of Thermal Diffusion Effects on CVD Silicon Carbide Thin-Film Deposition

by Peng Su, Xinxin Yang, Siyuan Tang, Liangcan Fu and Lijun Liu

Crystals 2026, 16(8), 481; https://doi.org/10.3390/cryst16080481 - 23 Jul 2026

During the preparation of silicon carbide (SiC) thin films by chemical vapor deposition (CVD), the Soret effect induced by a large temperature gradient influences the deposition rate and uniformity; its sensitivity to process parameters remains unclear. A computational fluid dynamics model coupling detailed [...] Read more.

During the preparation of silicon carbide (SiC) thin films by chemical vapor deposition (CVD), the Soret effect induced by a large temperature gradient influences the deposition rate and uniformity; its sensitivity to process parameters remains unclear. A computational fluid dynamics model coupling detailed gas-phase and surface reaction kinetics was developed and validated for a cold/warm wall vertical CVD reactor. Comparing simulations with and without the thermal diffusion term reveals the dual role—suppressing deposition rate while degrading film uniformity. The thermal diffusion contributions to deposition rate (TDC_GR) and uniformity (TDC_GU) are introduced as quantitative metrics, and simulations evaluated the effects of inlet–substrate temperature difference (ΔT), reactor pressure (p), substrate rotation speed (ω), and carrier gas flow rate (Q) on the Soret effect, clarifying optimal conditions. Results show ΔT dominates. At ΔT = 1700 K, TDC_GR = −56.39% and TDC_GU = 5.29%. Pressure affected TDC_GR negligibly but significantly reduced TDC_GU by enhancing gas-phase mixing; increasing p from 7500 to 12,500 Pa led to a decrease in TDC_GU from 4.19% to 1.93%. Optimal parameters (ΔT = 1400 K, p = 12,500 Pa, ω = 800 rpm, Q = 50 slm) achieved a deposition rate of 10.71 μm/h and non-uniformity of 0.45%. These findings provide theoretical guidance for precise SiC-CVD process control in cold- or hot-wall vertical reactor architectures. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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20 pages, 19197 KB

Open AccessArticle

Precursor Ratio-Driven Morphological Evolution of CVD-Grown MoS₂ Microstructures

by Sobin Mathew, Bernd Hähnlein, Dominik Flock, Vladislav Kurtash, Heiko O. Jacobs and Jörg Pezoldt

Crystals 2026, 16(8), 480; https://doi.org/10.3390/cryst16080480 - 23 Jul 2026

The morphology of CVD-grown molybdenum disulfide (MoS₂) is sensitive to the local precursor environment, which governs nucleation density, edge stability, and growth kinetics. In this work, we systematically investigate the effect of precursor ratio on the morphological evolution of MoS₂ [...] Read more.

The morphology of CVD-grown molybdenum disulfide (MoS₂) is sensitive to the local precursor environment, which governs nucleation density, edge stability, and growth kinetics. In this work, we systematically investigate the effect of precursor ratio on the morphological evolution of MoS₂ microstructures synthesized by atmospheric-pressure chemical vapor deposition on SiO₂/Si substrates. By varying the relative amounts of MoO₃ and sulfur precursors, distinct growth regimes were obtained, ranging from compact hexagonal and quasi-circular domains to multilayer hexagonal structures, triangular domains, and dendritic morphologies. At higher MoO₃ loading, growth is dominated by dense nucleation, leading to isolated few-layer hexagonal domains. A moderate reduction in Mo precursor concentration promotes diffusion-assisted growth and secondary nucleation, resulting in multilayer hexagonal structures with aligned or slightly rotated stacked layers. Under sulfur-rich conditions, morphology evolves into triangular domains due to anisotropic edge stabilization, while further increase in sulfur concentration gives rise to branched dendritic structures through kinetically limited, diffusion-dominated growth. Cross-sectional FIB analysis reveals dense vertical stacking and lateral displacement of upper layers in the multilayer hexagonal domains. Raman and photoluminescence measurements confirm strong correlations between morphology, layer thickness, and optical response, with thinner regions exhibiting reduced Raman peak separation, enhanced photoluminescence intensity, and blue-shifted excitonic transitions. The results show that, under fixed APCVD reactor geometry, source positions, temperature profile, carrier-gas flow, and nominal growth duration, the nominal MoO₃ to sulfur source-loading ratio reproducibly correlates with the transition between compact hexagonal, multilayer hexagonal, triangular, and dendritic MoS₂ morphologies on amorphous SiO₂/Si substrates. Because vapor-phase Mo- and S-containing partial pressures were not directly measured, this ratio is treated as a nominal source-inventory descriptor rather than as a direct vapor-phase stoichiometric ratio. The observed trends are interpreted using a qualitative thermodynamic and kinetic framework based on precursor fluence, nucleation density, edge stability, and diffusion-limited growth. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

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2 pages, 115 KB

Open AccessCorrection

Correction: Cui et al. Gemological Study of Black Nephrite from Dahua, Guangxi Province, China. Crystals 2026, 16, 220

by Mingying Cui, Mingyue He, Mei Yang, Bijie Peng and Shaokun Wu

Crystals 2026, 16(8), 479; https://doi.org/10.3390/cryst16080479 - 23 Jul 2026

Error in Table [...] Full article

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