Crystals

23 pages, 4432 KB

Open AccessArticle

Hydrogen-Rich Mixed Anionic Halides with a Strong Response to UV–Vis Radiations for Photonic and Energy Storage Applications

by Ali Yaqoob, Shamsher Ahmad, Muhammad Usman Khan, Nawishta Jabeen, Ghada A. Alsawah, Muhammad Adnan Qaiser, Hafedh Mahmoud Zayani and Ahmad Hussain

Crystals 2026, 16(5), 344; https://doi.org/10.3390/cryst16050344 - 18 May 2026

Abstract

In this study, density functional theory (DFT)-based investigations are carried out using the CASTEP code. The plane-wave pseudopotential method is used to explore the multifunctional properties, including the structural, electronic spectra, thermo-mechanical and hydrogen storage properties, of hydrogen-rich mixed-anionic (Li₃H₄ [...] Read more.

In this study, density functional theory (DFT)-based investigations are carried out using the CASTEP code. The plane-wave pseudopotential method is used to explore the multifunctional properties, including the structural, electronic spectra, thermo-mechanical and hydrogen storage properties, of hydrogen-rich mixed-anionic (Li₃H₄N₂X, where X = F, Cl, Br, and I) halides. The exchange–correlation interactions are treated within the generalized gradient approximation (GGA) using the Perdew–Burke–Ernzerhof (PBE) functional, while the hybrid HSE06 function is used for accurate band gap predictions. Moreover, the optical properties of the halides are analyzed under the influence of UV–Vis radiation instances. The band gap values of these orthorhombic-structured halides lie in the visible-to-UV regions of radiation, with values of 2.97 eV, 3.12 eV, 3.06 eV and 3.28 eV, respectively. Such band gap values allow these materials to absorb nearly 75% to 90% of incoming radiation, with absorption values around (10⁵ cm⁻¹). These favorable opto-electronic responses make these halides suitable for solar radiation energy conversion applications. Stable thermodynamic responses and the mechanical nature of the mixes (brittle for Li₃H₄N₂Br and ductile for the rest) reveal their practical applicability for flexible photonics. Moreover, due to the presence of rich hydrogen atoms, the Li₃H₄N₂F halide exhibits a gravimetric ratio of around 6.0 wt%, which is higher than the standard (5.5 wt%) value defined by the US DOE. Similarly, GHSC values of 2.5 wt% for Li₃H₄N₂I, 3.5 wt% for Li₃H₄N₂Br, and 5.0 wt% for Li₃H₄N₂Cl are reported; these values indicate that these compounds possess strong potential for use in the hydrogen fuel cells required in light-duty vehicles. Full article

► Show Figures

Figure 1

14 pages, 1186 KB

Open AccessArticle

Mechanical and Surface Characterization of Lithography-Based Ceramic Manufactured Zirconia for Dental Applications

by Abdullah Alshamrani and Majed M. Alsarani

Crystals 2026, 16(5), 343; https://doi.org/10.3390/cryst16050343 - 18 May 2026

Abstract

This study evaluated and compared the mechanical performance of conventionally milled zirconia and two additively manufactured zirconia ceramics fabricated using Lithography-based Ceramic Manufacturing (LCM) technology for potential use in load-bearing dental restorations. A total of 150 zirconia specimens were prepared and allocated into [...] Read more.

This study evaluated and compared the mechanical performance of conventionally milled zirconia and two additively manufactured zirconia ceramics fabricated using Lithography-based Ceramic Manufacturing (LCM) technology for potential use in load-bearing dental restorations. A total of 150 zirconia specimens were prepared and allocated into three material groups: milled zirconia and LCM-printed zirconia (LithaCon 3Y 210 and LithaCon 3Y 230), each subdivided into non-aged (control, C) and thermocycled aged (A) conditions (n = 25 per condition). Specimens were standardized using CAD and fabricated by milling or LCM printing. Flexural strength was assessed using a three-point bending test in accordance with ISO 6872:2024, nanoindentation hardness was measured with a Berkovich indenter following ISO 14577-1:2015, and surface roughness was evaluated using optical profilometry per ISO 21920-2:2021. Flexural strength showed no significant differences among groups, while hardness and surface roughness varied significantly. LCM zirconia demonstrated comparable flexural strength to milled zirconia, although milled materials exhibited higher hardness. The 210A group showed the most favorable overall mechanical profile, warranting further investigation of long-term performance. Full article

(This article belongs to the Special Issue Advances in New Functional Biomaterials for Medical Applications, Second Edition)

10 pages, 1115 KB

Open AccessArticle

Profiling Intermolecular Interactions of Theophylline: Analysis of Some Classes of Theophylline Containing Co-Crystals

by Martin H. Polko and Guido J. Reiss

Crystals 2026, 16(5), 342; https://doi.org/10.3390/cryst16050342 - 18 May 2026

Abstract

Intermolecular interactions play an important role in the formation and stability of co-crystals. In this study, the interaction behaviour of theophylline in co-crystal structures was systematically analysed using data from the Cambridge Structural Database. A total of fifty-three theophylline co-crystal structures were investigated [...] Read more.

Intermolecular interactions play an important role in the formation and stability of co-crystals. In this study, the interaction behaviour of theophylline in co-crystal structures was systematically analysed using data from the Cambridge Structural Database. A total of fifty-three theophylline co-crystal structures were investigated and classified according to their intermolecular interaction motifs. A structured interaction scheme was developed to describe the accessible interaction sites of theophylline, including classical and non-classical hydrogen bonds, as well as halogen bonds and π∙∙∙π interactions. The study revealed theophylline’s high versatility in forming intermolecular interactions, resulting in twenty interaction patterns. Three dominant motifs were identified as occurring most frequently. The results indicate that steric effects influence the accessibility of specific interaction sites, particularly limiting interactions at the carbonyl group located between the two methyl groups. Hirshfeld surface analysis revealed that O∙∙∙H and H∙∙∙H interactions contribute most significantly to the intermolecular interactions in the analysed structures. Full article

(This article belongs to the Section Crystal Engineering)

► Show Figures

Figure 1

16 pages, 4031 KB

Open AccessArticle

Recovery of Lithium from Spent Lithium-Ion Batteries Through Pyrolysis Reduction

by Peng Hu, Haoxiang Wu, Liuli Yao, Jun Yao, Tao Zhang, Siwei Jiang, Xintao Wu, Yazecheng Liu, Jun Li, Peng Dong, Zhongren Zhou and Yingjie Zhang

Crystals 2026, 16(5), 341; https://doi.org/10.3390/cryst16050341 - 18 May 2026

Abstract

In this paper we investigate the use of sucrose as a reducing agent for the carbothermal reduction in spent ternary cathode materials. During this process, lithium from the cathode material is converted into water-soluble Li₂CO₃, while the high-valent transition [...] Read more.

In this paper we investigate the use of sucrose as a reducing agent for the carbothermal reduction in spent ternary cathode materials. During this process, lithium from the cathode material is converted into water-soluble Li₂CO₃, while the high-valent transition metals are reduced to insoluble metallic elements and oxides. The influence of various pyrolysis temperatures, sucrose dosages, and pyrolysis times on the reduction degree of high-valent metals. Furthermore, the influence of leaching conditions on lithium recovery efficiency is examined. Under the optimal conditions of a pyrolysis temperature of 650 °C, a sucrose dosage of 15 wt.%, a pyrolysis time of 30 min, a leaching solid–liquid ratio of 30 g/L, and a leaching time of 30 min, the lithium leaching rate reaches 97.9%. Characterization via XRD, XPS and SEM reveals that sucrose serves as an effective carbothermal reducing agent. It facilitates the reduction of high-valent transition metals to insoluble metallic elements and oxides while simultaneously enabling the recovery of lithium as Li₂CO₃. Consequently, this method achieves an efficient separation of lithium from other metallic elements. Compared to traditional recycling processes, it avoids the low lithium recovery rates often associated with subsequent separation steps. Full article

(This article belongs to the Special Issue Electrode Materials in Lithium-Ion Batteries)

► Show Figures

Figure 1

18 pages, 36073 KB

Open AccessArticle

Processing Route Dependence of Microstructure and Mechanical Properties in an Al-Li-Mg Alloy for Lightweight Sports Equipment

by Ge Liu, Shenchen Zhang, Yuncheng Zhu, Xin Li, Yingchao Zhao, Dengfeng Yin and Ming-Chun Zhao

Crystals 2026, 16(5), 340; https://doi.org/10.3390/cryst16050340 - 18 May 2026

Abstract

The pursuit of lightweight, high-performance sports equipment drives the development of Al-Li-Mg alloys, yet systematic studies linking a complete processing route, from as-cast to peak-aged condition, to microstructural evolution and mechanical properties remain limited. This work provides the first comprehensive investigation of how [...] Read more.

The pursuit of lightweight, high-performance sports equipment drives the development of Al-Li-Mg alloys, yet systematic studies linking a complete processing route, from as-cast to peak-aged condition, to microstructural evolution and mechanical properties remain limited. This work provides the first comprehensive investigation of how a sequential processing route (homogenization, hot rolling, solution treatment, and peak aging) transforms the coarse as-cast structure of an Al-Li-Mg alloy into a refined, recrystallized grain architecture with a uniform dispersion of nanoscale δ′-Al₃Li precipitates. This microstructural transformation leads to a dramatic enhancement in mechanical properties: the peak-aged alloy exhibits increases of approximately 92%, 139%, and 925% in yield strength, ultimate tensile strength, and elongation, respectively, relative to the as-cast condition. The dominant strengthening mechanism is identified as dislocation shearing of coherent δ′-Al₃Li precipitates (average radius ~5 nm, well below the ~25 nm transition threshold for Orowan looping), which enhances strength without compromising ductility, demonstrating the critical role of the processing route in tailoring microstructures and mechanical properties for lightweight sports equipment. Full article

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

► Show Figures

Figure 1

5 pages, 167 KB

Open AccessEditorial

Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds (3rd Edition)

by Waldemar Maniukiewicz

Crystals 2026, 16(5), 339; https://doi.org/10.3390/cryst16050339 - 18 May 2026

Abstract

The third edition of the Special Issue of Crystals, entitled “Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds”, continues to serve as a high-profile forum for researchers to share their latest findings in the field of coordination chemistry [...] Full article

(This article belongs to the Special Issue Synthesis, Crystal Structures and Hirshfeld Surface Analysis of Coordination Compounds (3rd Edition))

17 pages, 1506 KB

Open AccessArticle

Exploring Monohalogen-Substituted Phenylethylamine Hydro-Chloride Salts: Preparation and Solid Phase Analysis of Pharma-Ceutical Building Blocks and Resolving Agents

by Sven Tiedemann, Wilko Fokken, Heike Lorenz and Jan von Langermann

Crystals 2026, 16(5), 336; https://doi.org/10.3390/cryst16050336 - 17 May 2026

Abstract

Monohalogen-substituted (F-, Cl-, Br-) phenylethylamine derivates are a valuable class of chiral compounds, e.g., for C-C-coupling reactions, which are the basis for multiple pharmaceuticals and resolving agents. Here, the solid phase behavior of the underlying phenylethylamine derivates, especially of the corresponding hydrochloride salts, [...] Read more.

Monohalogen-substituted (F-, Cl-, Br-) phenylethylamine derivates are a valuable class of chiral compounds, e.g., for C-C-coupling reactions, which are the basis for multiple pharmaceuticals and resolving agents. Here, the solid phase behavior of the underlying phenylethylamine derivates, especially of the corresponding hydrochloride salts, is highly relevant as those compounds are often applied in enantiopure form during the production processes. In this study, the solid phase behavior of 20 synthesized chiral phenylethylamine hydrochloride derivates (both enantiomers and racemates) was investigated including detailed information regarding melting behavior, powder X-ray diffraction data and the type of the chiral system present. Further, the binary melt phase diagram of a found conglomerate system and two novel enantiomer crystal structures were determined. This study is aimed at revealing structure–phase behavior relationships for the 20 monohalogen-substituted compounds investigated as well as providing basic solid–phase-related data required for later crystallization-based enantioseparation processes. Full article

14 pages, 3986 KB

Open AccessArticle

Enhanced Properties of Electrodes Based on Ti/TiO₂-Au/rGO Composite Structures for Electrochemical Application

by Cornelia Bandas, Mina-Ionela Morariu, Corina Orha, Carmen Lazau and Mircea Nicolaescu

Crystals 2026, 16(5), 338; https://doi.org/10.3390/cryst16050338 - 16 May 2026

Abstract

The increasing environmental pollution with emergent pollutants has led to the necessity to develop various structures for sensory applications used in water monitoring processes. In this context, this study presents a composite structure based on titanium foil/titanium dioxide/reduced graphene oxide functionalized with gold [...] Read more.

The increasing environmental pollution with emergent pollutants has led to the necessity to develop various structures for sensory applications used in water monitoring processes. In this context, this study presents a composite structure based on titanium foil/titanium dioxide/reduced graphene oxide functionalized with gold ions (Ti/TiO₂-Au/rGO) obtained by a simple and efficient spin-coating method, successfully applied in electrochemical doxorubicin detection processes. The synthesis protocol first involves etching the titanium foil to form a Ti/TiO₂ substrate, followed by the synthesis of the TiO₂-Au/rGO solution, which was deposited by a spin-coating technique on the surface of the Ti/TiO₂ support, to form electrodes based on a Ti/TiO₂-Au/rGO composite structure. The structure and morphology of the as-synthesized composites were investigated in detail using X-ray analysis, Raman spectroscopy, and scanning electron microscopy coupled with an EDX. Furthermore, to determine the electroactive surface area and apparent diffusion coefficient of the composite structures, the electrochemical behavior was evaluated by CV in a 1 M KNO₃ and in the presence of 4 mM K₃Fe(CN)₆. By using electrochemical impedance spectroscopy (EIS) in 0.1 M NaOH supporting electrolyte and within a frequency range of 0.1–10,000 Hz and a voltage of 10 mV, the charge transfer resistance was also investigated. The potential application in electroanalysis of the electrodes was tested by CV for the detection of the DOX pollutant in 0.1 M NaOH and 1–5 mg L⁻¹ DOX. The obtained results provide new insights into the development of electrochemical sensors for applications in water treatment processes. Full article

(This article belongs to the Special Issue Synthesis and Applications of Crystalline Nanoporous Materials)

► Show Figures

Figure 1

13 pages, 2534 KB

Open AccessArticle

Slower Load-Dependent Increase and Logarithmic Rate Dependence of Friction in Suspended WS₂

by Ketong Zhang, Haoran Yao, Jianheng Sun, Xiaosen Ren, Zhifei Yao, Bohui Zhao, Qiuyuan Sun, Jiuyan Wei, Qiang Zhu, Hao Guo, Zhonghao Li, Xin Li, Huanfei Wen, Jun Tang, Yanjun Li, Sugawara Yasuhiro, Zongmin Ma and Jun Liu

Crystals 2026, 16(5), 337; https://doi.org/10.3390/cryst16050337 - 16 May 2026

Abstract

Suspended two-dimensional (2D) materials in high-performance devices exhibit unique properties that are critically important for nanoscale mechanical and electromechanical applications, while their frictional laws remain poorly understood. Here, we investigate the nanoscale frictional behavior of suspended WS₂ flakes under varying applied loads [...] Read more.

Suspended two-dimensional (2D) materials in high-performance devices exhibit unique properties that are critically important for nanoscale mechanical and electromechanical applications, while their frictional laws remain poorly understood. Here, we investigate the nanoscale frictional behavior of suspended WS₂ flakes under varying applied loads and scanning rates using atomic force microscopy (AFM), and successfully employ the Bowden–Tabor theory and the thermally activated Prandtl–Tomlinson (PTT) model to analyze the load- and scanning-rate-dependent friction characteristics of suspended 2D systems. The results show that suspended WS₂ exhibits higher friction than supported WS₂, whereas its friction increases more slowly with applied load, which can be well described by the Bowden–Tabor theory. Moreover, the friction exhibits a logarithmic dependence on scanning rate for both suspended and supported WS₂. Quantitative analysis within the framework of the PTT model demonstrates that this model can be successfully extended to describe the rate-dependent friction of suspended WS₂, providing a unified framework for both supported interfaces and suspended 2D systems. This work provides valuable guidance for understanding frictional dissipation mechanisms relevant to the design and optimization of WS₂-based devices. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

► Show Figures

Figure 1

29 pages, 3860 KB

Open AccessReview

Unraveling the Underlying Mechanism of the Li⁺ Migration Inside Halide Solid-State Electrolytes: Structural Tuning and Defect Manipulation

by Yiqiao Xu, Jingzheng Weng, Qiyong Li, Ting Luo and Yi Zhang

Crystals 2026, 16(5), 335; https://doi.org/10.3390/cryst16050335 - 15 May 2026

Abstract

Halide-based solid electrolytes have emerged as promising candidates for next-generation all-solid-state lithium metal batteries due to their high room-temperature ionic conductivity, wide electrochemical stability window, and favorable mechanical properties. This review provides a comprehensive overview of the fundamental structure–property relationships, Li⁺ transport [...] Read more.

Halide-based solid electrolytes have emerged as promising candidates for next-generation all-solid-state lithium metal batteries due to their high room-temperature ionic conductivity, wide electrochemical stability window, and favorable mechanical properties. This review provides a comprehensive overview of the fundamental structure–property relationships, Li⁺ transport mechanisms, and performance optimization strategies for Li₃MX₆-type halide solid electrolytes. The unique structural framework of halide electrolytes, characterized by close-packed anion sublattices (hexagonal close-packed and cubic close-packed) and edge-sharing [MX₆]³⁻ octahedral networks, establishes three-dimensional Li⁺ percolation pathways with low migration barriers (0.20–0.33 eV). This review concludes by identifying key challenges and future research directions, including high-entropy halide design, scalable aqueous synthesis methods, earth-abundant material alternatives, and integrated cell architectures that combine halide catholytes with complementary anolyte materials for practical all-solid-state battery applications. Full article

(This article belongs to the Section Materials for Energy Applications)

► Show Figures

Figure 1

21 pages, 11691 KB

Open AccessArticle

Microstructural Evaluation of Plasma-Vitrified Wind Turbine Blade Slag and Its Alternative Application in Geopolymer

by Vilma Snapkauskienė, Regina Kalpokaitė-Dičkuvienė, Arūnas Baltušnikas and Viktorija Grigaitienė

Crystals 2026, 16(5), 334; https://doi.org/10.3390/cryst16050334 - 15 May 2026

Abstract

With the rapid expansion of wind energy infrastructure, there is an increasing accumulation of wind turbine blade waste (WTBW), which is mainly composed of glass fiber-reinforced thermosetting composites. Due to the irreversible nature of polymer crosslinking, conventional recycling methods remain limited. In this [...] Read more.

With the rapid expansion of wind energy infrastructure, there is an increasing accumulation of wind turbine blade waste (WTBW), which is mainly composed of glass fiber-reinforced thermosetting composites. Due to the irreversible nature of polymer crosslinking, conventional recycling methods remain limited. In this study, plasma vitrification was employed to convert WTBW into a reactive calcium-aluminum-silicate slag suitable for use in geopolymer materials. Plasma treatment at a temperature of approximately 2750 K resulted in the formation of predominantly amorphous vitrified slag (VS). Structural characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) revealed the spatial heterogeneity of the VS. This heterogeneity was influenced by thermal gradients and varied between samples collected from different slag discharge zones, both vertically and horizontally from the reactor. All VS samples contained between 30 and 89% amorphous phase and 10–55% anorthite, with the proportions varying by sampling location. Chemical stability tests showed the dissolution of calcium and aluminum in acidic media, resulting in a silica-enriched residual structure in which the Ca and Al content decreased to less than 0.5 at.% after 100 days. In contrast, exposure to alkaline media caused only minimal surface reorganization—the addition of 5 wt.% VS to acid-based geopolymers made with two metakaolin precursors resulted in a 35% decrease in the mechanical strength of pure metakaolin-based systems. In contrast, when metakaolin containing illite impurities was used, strength values were similar to those of the reference geopolymer. The results quantitatively demonstrate that plasma-derived slag exhibits composition-dependent reactivity, directly linked to its amorphous content and dissolution behavior. Full article

(This article belongs to the Special Issue Synergizing Crystallography, Mineral Materials Science and Solid Waste Upcycling for Sustainable Materials Innovation)

► Show Figures

Figure 1

12 pages, 299 KB

Open AccessArticle

Flexoelectric Instability in Bent-Core Nematic Liquid Crystals

by Ahlam Almamari and Mikhail Osipov

Crystals 2026, 16(5), 333; https://doi.org/10.3390/cryst16050333 - 15 May 2026

Abstract

We develop a theoretical model for the flexoelectric instability in bent-core nematic liquid crystals, focusing on the coupling between elastic distortions and an external electric field through flexoelectric polarization. The analysis is carried out in the nematic phase close to the twist-bend transition, [...] Read more.

We develop a theoretical model for the flexoelectric instability in bent-core nematic liquid crystals, focusing on the coupling between elastic distortions and an external electric field through flexoelectric polarization. The analysis is carried out in the nematic phase close to the twist-bend transition, where both the flexoelectric coefficients and the effective bend elastic constant exhibit strong temperature dependence. Within a Landau–de Gennes framework, we derive analytical expressions for the threshold electric field and the corresponding wave vector of the emerging periodic modulation by minimizing the total free energy and assuming

K_{1} = K_{2}

. Numerical simulations illustrate the temperature dependence of the threshold parameters and the role of dielectric anisotropy and elastic constants. The results indicate that the flexoelectric instability may occur only within a finite temperature interval above the transition into the twist-bend phase and that both the threshold electric field and the periodic structure’s wave vector decrease as the temperature decreases. Full article

(This article belongs to the Collection Liquid Crystals and Their Applications)

► Show Figures

Figure 1

24 pages, 4570 KB

Open AccessArticle

Empirical Screening of Two Laser Processing Conditions with Respect to Graphitic Ordering and Electrochemical Performance of PEI-Derived Laser-Induced Carbon

by Pamela Rivera Rivera, Šarūnas Mickus, Aušra Selskienė, Tomas Murauskas, Sandra Stanionytė, Romualdas Trusovas, Justina Gaidukevič and Rasa Pauliukaite

Crystals 2026, 16(5), 332; https://doi.org/10.3390/cryst16050332 - 15 May 2026

Abstract

Laser-induced graphene (LIG) enables rapid conversion of polymer substrates into conductive carbon materials. In this study, nitrogen-containing carbon nanomaterials were fabricated on polyetherimide (PEI) substrates using empirical screening of two specific process points. The resulting materials were characterized using scanning electron microscopy, Raman [...] Read more.

Laser-induced graphene (LIG) enables rapid conversion of polymer substrates into conductive carbon materials. In this study, nitrogen-containing carbon nanomaterials were fabricated on polyetherimide (PEI) substrates using empirical screening of two specific process points. The resulting materials were characterized using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy to correlate structural features with electron-transfer behavior. Raman and XPS analyses showed different structure and morphology depending on irradiation regime. The carbon materials with a higher sp³ fraction (≈55–59%), larger in-plane crystallite size (L_a up to 8.0 nm), and pronounced π–π* shake-up satellites indicated enhanced graphitic ordering when a shorter nanosecond laser was used. These structural differences resulted in substantially lower charge-transfer resistance (0.53–0.79 kΩ·cm³) and larger electroactive surface areas for the porous electrodes compared with foam structured carbon nanomaterials. The results show that, under the selected fabrication conditions, variations in laser processing parameters correspond to differences in graphitic ordering and electron-transfer properties in PEI-derived laser-induced carbon materials. Full article

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

► Show Figures

Figure 1

19 pages, 5246 KB

Open AccessArticle

Inhomogeneities Generating Mechanisms in Membranes

by Samo Penič, Luka Mesarec, Veronika Kralj-Iglič, Aleš Iglič and Samo Kralj

Crystals 2026, 16(5), 331; https://doi.org/10.3390/cryst16050331 - 14 May 2026

Abstract

Spatial inhomogeneities are essential for biological membrane function. They could trigger structural transformations in membranes as well as changes in their global behaviours, and influence intercell communications. This study investigates how curvature-enforcing inclusions and in-plane orientational order generate such patterns. We focus on [...] Read more.

Spatial inhomogeneities are essential for biological membrane function. They could trigger structural transformations in membranes as well as changes in their global behaviours, and influence intercell communications. This study investigates how curvature-enforcing inclusions and in-plane orientational order generate such patterns. We focus on membranes exhibiting spherical topology, consisting of primary (lipids) and secondary (inclusions) constituents. Using Monte Carlo simulations, we show that, for a high enough concentration of inclusions, a budding instability appears below a critical temperature. The complexity of patterns is further increased if membranes exhibit in-plane order. According to the Gauss–Bonnet and Poincare–Hopf theorems in membranes of non-toroidal topology, topological defects are inevitably formed which introduce centres exhibiting strongly local elastic distortions. Regions exhibiting a large enough local curvature could trigger additional pairs of defects. Furthermore, condensed in-plane order could generate a Flory–Huggins-type contribution, promoting the assembly of membrane inclusions. Finally, memory effects are expected to play an important role. Full article

► Show Figures

Figure 1

14 pages, 4732 KB

Open AccessArticle

Synthesis and Characterization of Sintered and Double-Sintered Invar Alloy from Mechanically Alloyed Powders

by Călin-Virgiliu Prica, Argentina Niculina Sechel, Traian Florin Marinca and Florin Popa

Crystals 2026, 16(5), 330; https://doi.org/10.3390/cryst16050330 - 14 May 2026

Abstract

The alloy with a chemical composition of 64 at. % Fe and 36 at. % Ni is known as Invar36 and is characterized by a coefficient of thermal expansion (CTE) less than 2 × 10⁻⁶ °C⁻¹ below Curie temperature (about 250 [...] Read more.

The alloy with a chemical composition of 64 at. % Fe and 36 at. % Ni is known as Invar36 and is characterized by a coefficient of thermal expansion (CTE) less than 2 × 10⁻⁶ °C⁻¹ below Curie temperature (about 250 °C). The conventional method of obtaining Invar36 alloys consists of melting and casting, followed by a series of heat treatments. In recent years, research has focused on unconventional technologies for Invar36 preparation such as the sintering of Fe and Ni elemental powders. Also, Invar36 in powder form can be synthesized by mechanical alloying (MA). The aim of this paper is the characterization of Invar36 compacts obtained by conventional sintering of mechanically alloyed Fe and Ni elemental powders. MA was performed in a high-energy planetary ball mill (Ar atmosphere). Mechanically alloyed powders were densified by conventional sintering (simple and double). The sintering parameters used are those specific to the sintering of ferrous parts. After simple sintering, the relative density was 74%. Re-pressing and double sintering lead to an increase in the relative density to 78.6%. The microstructure of Invar36 compacts consists of two phases. The coefficient of thermal expansion (CTE) was determined for Invar36 compacts obtained by both simple and double sintering at 1120 °C in endogas. The CTE values of Invar36 simple sintered (α = 0.6 × 10⁻⁶ °C⁻¹) and double sintered (α = 0.5 × 10⁻⁶ °C⁻¹) are very low, up to 195 and 225 °C, respectively. HV_0.05 values of the Invar-ss sample are lower than the values of the Invar-ds sample. Thus, the HV_0.05 value in areas where the γ phase predominates increases from 203 to 218, while in areas where the α phase is predominant it increases from 257 to 271. The results of this study have potential applicability in obtaining Invar parts by sintering under the specific conditions used for ferrous parts, without requiring any modification of the production flow. Full article

(This article belongs to the Special Issue Nanocrystalline Materials Processing and Characterization)

► Show Figures

Figure 1

15 pages, 3200 KB

Open AccessArticle

Ab Initio Study on the Structural, Mechanical, Vibrational and Thermal Properties of Norbergite-Structured Vanadium Borate (V₃BO₆)

by Sabit Korcak

Crystals 2026, 16(5), 329; https://doi.org/10.3390/cryst16050329 - 13 May 2026

Abstract

Vanadium borate (V₃BO₆) has recently been synthesized and identified as a promising material for use in energy storage applications, particularly as a potential anode for lithium-ion batteries. However, despite previous studies highlighting its electrochemical performance, a comprehensive understanding of [...] Read more.

Vanadium borate (V₃BO₆) has recently been synthesized and identified as a promising material for use in energy storage applications, particularly as a potential anode for lithium-ion batteries. However, despite previous studies highlighting its electrochemical performance, a comprehensive understanding of its intrinsic mechanical, thermal, and vibrational properties remains limited. The compound crystallizes in an orthorhombic phase with the Pnma (No. 62) space group. To explore its intrinsic physical characteristics, full geometry optimization of the unit cell and atomic positions was performed using density functional theory (DFT) within the CASTEP framework. The Perdew–Burke–Ernzerhof (PBE) functional under the generalized gradient approximation (GGA) was used to model exchange–correlation effects. A plane-wave cut-off of 408 eV and a 6 × 6 × 13 Monkhorst–Pack grid were employed to ensure numerical convergence. The optimized lattice constants (a = 9.9025 Å, b = 8.4751 Å and c = 4.5354 Å) are highly consistent with experimental data, which confirms the reliability of the computational approach adopted. The elastic behaviour was further investigated using the first-principles strain-energy method, yielding nine independent elastic constants consistent with orthorhombic symmetry. The calculated bulk and shear moduli, along with the anisotropy parameters, suggest that V₃BO₆ has a favourable balance of mechanical robustness and moderate ductility. A Vickers hardness of 10.95 GPa and a B/G ratio of approximately 1.93 corroborate these findings. Additional parameters, such as Poisson’s ratio, Debye temperature and average sound velocities, were derived to gain deeper insight into the material’s thermomechanical performance. These results provide a solid theoretical foundation for understanding the mechanical stability and potential anode suitability of V₃BO₆ in lithium-ion battery systems. Full article

(This article belongs to the Section Polycrystalline Ceramics)

► Show Figures

Figure 1

33 pages, 15853 KB

Open AccessReview

Development and Evolution of Crystallographic Software: From Standalone Tools to Intelligent Integrated Platforms

by Rui Yao, Rongrong Jia and Zhenjie Feng

Crystals 2026, 16(5), 328; https://doi.org/10.3390/cryst16050328 - 12 May 2026

Abstract

Crystallography is fundamental to elucidating the relationship between microscopic structure and macroscopic material properties, and its progress is closely associated with advances in computational tools and software. This review traces the development of crystallographic software from its origins in the 1960s at Oak [...] Read more.

Crystallography is fundamental to elucidating the relationship between microscopic structure and macroscopic material properties, and its progress is closely associated with advances in computational tools and software. This review traces the development of crystallographic software from its origins in the 1960s at Oak Ridge National Laboratory to contemporary integrated platforms. The main aspects covered include the establishment and advancement of structural databases such as CSD and ICSD, the development of single-crystal structure determination programs such as SHELX and Olex2, and the evolution of powder diffraction tools, represented by HighScore Suite and TOPAS, toward integrated platforms. Crystallographic visualization tools have likewise evolved from desktop-based programs such as VESTA and Mercury to modern web-based platforms (JSmol and NGL Viewer). Moreover, we discuss the future directions of crystallographic software, including machine-readable data ecosystems, the application of artificial intelligence in structure determination and prediction, and the development of cloud-based immersive visualization platforms. Overall, this review comprehensively shows the evolution, current situation, and future directions of crystallographic software, which is of certain help to the research and development in related fields. Full article

(This article belongs to the Section Crystal Engineering)

21 pages, 3173 KB

Open AccessArticle

The Study of Topological Phase Transition of One-Dimensional Disordered Su-Schrieffer-Heeger Model

by Xuezhi Wang, Yunlin Li, Yufu Liu, Zhen Lai, Yu Hang and Xunya Jiang

Crystals 2026, 16(5), 327; https://doi.org/10.3390/cryst16050327 - 12 May 2026

Abstract

Here we investigate the topological phase transition of a general one-dimensional (1D) disordered Su–Schrieffer–Heeger (SSH) model, with two tunable parameters, the disorder distribution center

ξ

and a dimensionless ratio k between the disorder strengths of the intracell and intercell hopping terms. First, for [...] Read more.

Here we investigate the topological phase transition of a general one-dimensional (1D) disordered Su–Schrieffer–Heeger (SSH) model, with two tunable parameters, the disorder distribution center

ξ

and a dimensionless ratio k between the disorder strengths of the intracell and intercell hopping terms. First, for each realization or the ensemble average, we numerically observe a topological phase transition (TPT) with quantized real-space winding number jump and disappearing of zero-energy edge states when the disorder strength increases. Second, surprisingly, we find that the critical point of TPT is determined by the equality between the geometry means of intracell and intercell hopping terms. Third, a new theory based on the redefined sublattices is developed, which proves that the critical condition of TPT of the 1D disordered model is governed by the equality of the products of odd and even hopping terms and agrees with our numerical results. The theory also shows that the sudden change picture of TPT, not the gradual inverse picture, is correct, and that the origin of TPT is from the sub-symmetry of the model. Fourth, other models with different parameters are also studied. The TPTs of these models also follow our theoretical predictions. These results contribute to a better understanding of TPTs in 1D disordered systems. Full article

(This article belongs to the Section Inorganic Crystalline Materials)

21 pages, 6652 KB

Open AccessArticle

Synthesis of Mn-Doped ZnS for UV Photodetector Applications: Physical, Optoelectronic, and Luminescent Properties

by Wael Z. Tawfik, Hasnaa Hamdy, Haifa A. Alqhtani, Ahmed A. Allam, Mohamed A. M. Ali and Mohamed Sh. Abdel-wahab

Crystals 2026, 16(5), 326; https://doi.org/10.3390/cryst16050326 - 12 May 2026

Abstract

In this study, zinc sulfide (ZnS) and manganese (Mn)-doped ZnS nanopowder were successfully prepared via a simple and cost-effective chemical precipitation method with various concentrations of Mn for use in UV photodetectors. The effects of Mn doping on the structural, morphological, and optoelectronic [...] Read more.

In this study, zinc sulfide (ZnS) and manganese (Mn)-doped ZnS nanopowder were successfully prepared via a simple and cost-effective chemical precipitation method with various concentrations of Mn for use in UV photodetectors. The effects of Mn doping on the structural, morphological, and optoelectronic properties of ZnS nanopowder were studied. Structural analysis showed that all samples had a cubic structure with crystallite sizes approximately in the region of 2–3 nm. The morphological analysis using scanning electron microscopy confirmed the formation of well-dispersed spherical nanoparticles. Photoluminescence spectra show that Mn doping increased the luminescence intensity and caused a red shift in the emission peaks. Electrical properties such as conductivity and dielectric constant showed marked improvement with increasing Mn content. The conductivity increased from 3.7 mΩ⁻¹·m⁻¹ for pure ZnS to 6.3 mΩ⁻¹·m⁻¹ for the 1.03 mol% Mn²⁺ sample. The performance of photodetectors was evaluated under UV light. It was revealed that the photodetector based on a sample with 1.03 mol% Mn²⁺ reached an optimum state with an EQE of 9.8%, a detectivity of 4.65 × 10⁹ Jones, and a responsivity of 3.64 × 10⁻² A/W, indicating the effectiveness of Mn doping in improving the photo-generated carrier collection. Full article

(This article belongs to the Special Issue Advances in Wide Bandgap Semiconductor Materials)

► Show Figures

Figure 1

Journal Description

Crystals

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI