Inorganics

21 pages, 5908 KB

Open AccessArticle

Optimization of Synthesis Parameters for the Preparation of Dysprosium, Holmium and Erbium Silicate Systems by Solid-State Reaction

by Vasile Cristian Ciomaga Hatnean, Aurel Pui and Monica Ciomaga Hatnean

Inorganics 2026, 14(9), 247; https://doi.org/10.3390/inorganics14090247 - 21 Sep 2026

Viewed by 225

Abstract

Rare earth silicate materials received growing attention in recent years, driven by their potential for use in thermal/environmental barrier coatings and for scintillation applications for gamma-ray and X-ray detectors.

R_{2}

SiO₅, R₂Si₂O₇ and

R_{4.67}

[...] Read more.

Rare earth silicate materials received growing attention in recent years, driven by their potential for use in thermal/environmental barrier coatings and for scintillation applications for gamma-ray and X-ray detectors.

R_{2}

SiO₅, R₂Si₂O₇ and

R_{4.67}

(SiO₄)₃O (where R = Dy, Ho and Er) have been prepared by the conventional solid-state synthesis method. Through a systematic study, we have optimized the synthesis conditions, from the choice of the precursor to the optimal temperature profile for the chemical reaction. We demonstrate that, despite an overlap of the thermal stability ranges of different rare earth silicate compounds and their polymorphs in the phase diagrams of the R-Si-O systems, it is feasible to prepare polycrystalline materials with a high yield of the target phase. Moreover, we offer our perspectives into the kinetics of the different chemical phases within the rare earth silicate systems. We show that the chemical reactions are faster when employing the

α

-cristobalite polymorph of SiO₂ as a precursor, and we establish a reliable and reproducible solid-state synthesis protocol for Dy₂SiO₅, Ho₂SiO₅, Er₂SiO₅, Ho₂Si₂O₇, Er₂Si₂O₇, Dy_4.67(SiO₄)₃O and Ho_4.67(SiO₄)₃O. We reveal the results of our efforts to optimize the synthesis conditions for the preparation of all Dy-, Ho-, and Er-based silicate phases, which can be extended to other members of the rare earth silicate families, enabling the synthesis of bulk materials with improved phase purity. Full article

(This article belongs to the Section Inorganic Solid-State Chemistry)

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25 pages, 12646 KB

Open AccessArticle

Electrical Response of a Piezoelectric Semiconductor PN Junction Under a Local Temperature Change: A Three-Interface Analytical Model

by Chengcheng Liu, Nenghui Huang, Jiale Jia and Wenbo Ren

Inorganics 2026, 14(9), 246; https://doi.org/10.3390/inorganics14090246 - 21 Sep 2026

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Abstract

Piezoelectric semiconductor PN junctions hold considerable promise for self-powered sensing, flexible electronics, energy harvesting, photodetection, and multifunctional micro/nanodevices. A local temperature change couples the built-in electrical response of the PN doping interface with the thermally induced response at the boundaries of the heated [...] Read more.

Piezoelectric semiconductor PN junctions hold considerable promise for self-powered sensing, flexible electronics, energy harvesting, photodetection, and multifunctional micro/nanodevices. A local temperature change couples the built-in electrical response of the PN doping interface with the thermally induced response at the boundaries of the heated region, thereby modifying the electric potential, electric field, electric displacement, and carrier distributions near the junction. To elucidate this coupling mechanism, a one-dimensional three-interface analytical model is developed for a piezoelectric semiconductor PN junction subjected to a local temperature change. The fiber is divided into cold P-type, heated P-type, heated N-type, and cold N-type regions, and the coupled response is determined using piecewise analytical solutions together with open-circuit end conditions, interface continuity conditions, global carrier-conservation constraints, and reference-point conditions. Within a linear small-perturbation framework for an ideal zero-thickness homojunction, numerical results show that the PN doping interface governs the baseline distributions of the built-in potential and electric field, whereas the temperature interfaces generate additional electric fields through temperature-induced electric-displacement compensation, leading to localized redistribution of holes and electrons. For the baseline ZnO case with a 0.5 K temperature increment, the potential span is 9.124 mV, the peak electric-field magnitude is 48.43 kV m⁻¹, and the maximum carrier perturbation is 0.180 of its regional reference concentration. Independent Galerkin finite-element calculations agree with the analytical solution, with a maximum normalized discrepancy of 0.553% on the finest mesh. The temperature-change amplitude, heated-region half-width, reference carrier-concentration level, P/N doping asymmetry, effective dielectric constant, and effective thermal electric-displacement coefficient modify the potential transition, electric-field peaks, and carrier-screening range near the junction. These results reveal the coupled interaction between the local temperature interfaces and the PN doping interface and provide a theoretical basis for thermally regulating piezoelectric semiconductor junction devices under localized thermal loading. Full article

(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials, 5th Edition)

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6 pages, 201 KB

Open AccessEditorial

Editorial: Transition Metal Catalysts—Design, Synthesis, and Applications

by Wanli Zhang

Inorganics 2026, 14(9), 245; https://doi.org/10.3390/inorganics14090245 - 20 Sep 2026

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Abstract

Transition metals occupy a unique and pivotal position at the intersection of chemistry, materials science, and biology, owing to their diverse electronic configurations, variable oxidation states, and rich coordination chemistry [...] Full article

(This article belongs to the Special Issue Transition Metal Catalysts: Design, Synthesis and Applications)

37 pages, 2826 KB

Open AccessArticle

Photovoltaic-Relevant Optical and Dielectric Behavior of the Azo-Oxime Ligand and Its VO²⁺-, Cu²⁺-, and Fe³⁺-Based Complexes Films

by Kamal A. Aly, Tahani M. Shatir and Mohamad M. Ebrahium

Inorganics 2026, 14(9), 244; https://doi.org/10.3390/inorganics14090244 - 18 Sep 2026

Viewed by 282

Abstract

Cu²⁺, VO₂²⁺, and Fe³⁺ mononuclear complexes of the oxime-based ligand, 2-hydroxy-5-(p-tolyldiazenyl)benzaldehyde oxime (H₂L, 1), have been synthesized and structurally characterized by analytical, thermal, and spectral tools. They have been characterized by microanalyses [...] Read more.

Cu²⁺, VO₂²⁺, and Fe³⁺ mononuclear complexes of the oxime-based ligand, 2-hydroxy-5-(p-tolyldiazenyl)benzaldehyde oxime (H₂L, 1), have been synthesized and structurally characterized by analytical, thermal, and spectral tools. They have been characterized by microanalyses (C, H, and N), ¹H and ¹³C-NMR, FT-IR, UV-Vis, and/or ESR spectral measurements. The various analytics data indicate that the oxime-based ligand behaved as a neutral bidentate chelator binding Cu²⁺, VO²⁺, and Fe³⁺ cations via the nitrogen atom of the protonated oximatic group and protonated phenolic hydroxyl oxygen atom, adopting a distorted octahedral geometry. Furthermore, computational studies utilizing DFT/B3LYP/6-311(pd) include assessment of dipole moment, global reactivity descriptors, optimized geometry, LUMO-HOMO energy gaps, and molecular electrostatic potential image (MEP), which were estimated to support the geometrical structure of Cu²⁺, VO²⁺, and Fe³⁺ complexes. Furthermore, the optical parameters, viz. the refractive index (n) and extinction coefficient of azo-oxime ligand and its complexes, have been precisely estimated within a 300–1100 nm wavelength. The values of optical gap (E_gap) for the azo-oxime ligand and its complex films diminished from 2.96 eV for H₂L to 1.83 eV for the Fe³⁺ film; however; the n values follow an opposite behavior. The obtained n and E_g values are comparable to those reported for various semiconducting materials, suggesting the potential suitability of the investigated films for future semiconductor and optoelectronic applications. Although practical device performance remains to be evaluated, these low-cost and easily prepared materials could serve as promising candidates in these fields. Furthermore, the dielectric and nonlinear optical parameters have been thoroughly evaluated and comprehensively discussed. Full article

(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials, 4th Edition)

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19 pages, 16896 KB

Open AccessArticle

Biogenic ZnO Nanoparticles Derived from Eichhornia crassipes: Synthesis and Application in the Degradation of Multiple Organic Dyes and Chlorpyrifos Ethyl

by Nelson Nagles-Vergara, Jose Alejandro Villegas-Fuentes, Alfredo Rafael Vilchis-Nestor, Yuber Palacios-Torres, Efraím A. Serna-Galvis, Jorge L. Gallego and Priscy Alfredo Luque-Morales

Inorganics 2026, 14(9), 243; https://doi.org/10.3390/inorganics14090243 - 18 Sep 2026

Viewed by 327

Abstract

The green synthesis of zinc oxide (ZnO) nanoparticles using plant biomass offers a sustainable approach for developing photocatalytic materials for water treatment. In this study, ZnO nanoparticles were biosynthesized using aqueous extracts of Eichhornia crassipes from the Medio Atrato region, Chocó, Colombia, at [...] Read more.

The green synthesis of zinc oxide (ZnO) nanoparticles using plant biomass offers a sustainable approach for developing photocatalytic materials for water treatment. In this study, ZnO nanoparticles were biosynthesized using aqueous extracts of Eichhornia crassipes from the Medio Atrato region, Chocó, Colombia, at 1%, 2%, and 4% (w/v). The materials were characterized by FTIR, UV-Vis, XRD, and SEM–EDX. All samples exhibited the hexagonal wurtzite structure of ZnO without detectable secondary crystalline phases. Average crystallite sizes were 38.66, 38.16, and 31.52 nm for EC-1%, EC-2%, and EC-4%, respectively, decreasing with increasing extract concentration. Photocatalytic activity was evaluated under UV irradiation using six organic dyes: amido black 10B, eosin yellow, methylene blue, methyl orange, methyl red, and rhodamine B. Performance depended on both pollutant type and extract concentration. EC-2% showed the most consistent overall performance, achieving 87% degradation of amido black 10B, 92% of methyl orange, 81% of methyl red, and 93% of rhodamine B. Eosin yellow reached approximately 97% removal at 90 min, while EC-4% achieved 95% methylene blue degradation after 180 min. EC-2% also removed approximately 56.78% of chlorpyrifos ethyl after 180 min. Overall, E. crassipes-mediated ZnO nanoparticles demonstrate promising photocatalytic activity toward diverse organic pollutants and provide a potential route for valorizing invasive aquatic biomass. Full article

(This article belongs to the Special Issue Inorganic Photocatalysts for Environmental Applications, 2nd Edition)

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16 pages, 7069 KB

Open AccessArticle

Giving Molecular Cavity Wall Extensions to Pseudo [M(II)₇] (M = Co, Ni, Zn) Metallocalix[6]arenes

by Mari E. Slater-Parry, Seán T. Meally, Peter N. Horton, Simon J. Coles and Leigh F. Jones

Inorganics 2026, 14(9), 242; https://doi.org/10.3390/inorganics14090242 - 16 Sep 2026

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Abstract

Upon metal coordination, the upper rim modification of the Schiff base ligand 2-methoxy-6-((methylimino)methyl)phenol gives rise to a new family of [M(II)₇] (M = Co, Ni, Zn) pseudo metallocalix[6]arenes in the form of [Co(II)₇(OMe)₆(L₃)₆](NO [...] Read more.

Upon metal coordination, the upper rim modification of the Schiff base ligand 2-methoxy-6-((methylimino)methyl)phenol gives rise to a new family of [M(II)₇] (M = Co, Ni, Zn) pseudo metallocalix[6]arenes in the form of [Co(II)₇(OMe)₆(L₃)₆](NO₃)₂·2H₂O·3MeOH (1), [Ni(II)₇(OMe)₆(L₃)₆](NO₃)₂·2H₂O (4), [Zn(II)₇(OH)₂(OMe)₄(L₃)₆](NO₃)₂·10H₂O·4MeOH (5) and [Zn(II)₇(OMe)₆(L₄)₆](NO₃)₂·13H₂O·10MeOH (6), where L₃H = 2-methoxy-4-phenyl-6-[(methylimino)methyl]phenol and L₄H = 2-methoxy-4-tolyl-6-[(methylimino)methyl]phenol. The upper rim functionalisation provides this family with extensions to their molecular cavity walls when compared to their previously reported siblings. Attempts at encapsulating guest moieties (e.g., C₆₀) unexpectedly give rise to the dimeric complex [Co(II)Co(III)(L₃)₃(NO₃)₂]·H₂O (3). Full article

(This article belongs to the Section Coordination Chemistry)

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14 pages, 7562 KB

Open AccessArticle

Unraveling the Tl–Pb–Te System: Structural Identity of Tl₂Te and Tl₅Te₃

by Mykhailo Filep, Marian Sabov, Artem Pogodin, Tetyana Malakhovska and Tomash Sabov

Inorganics 2026, 14(9), 241; https://doi.org/10.3390/inorganics14090241 - 15 Sep 2026

Viewed by 286

Abstract

The present study investigates phase equilibria in the Tl–Pb–Te ternary system, which has been identified as a promising basis for the development of functional thermoelectric and topological materials. By applying differential thermal analyses, XRD, XPS and microstructural studies, it has been possible to [...] Read more.

The present study investigates phase equilibria in the Tl–Pb–Te ternary system, which has been identified as a promising basis for the development of functional thermoelectric and topological materials. By applying differential thermal analyses, XRD, XPS and microstructural studies, it has been possible to resolve the conflicting issues regarding the distinctiveness of the binary phases Tl₂Te and Tl₅Te₃. In a study of high-quality single crystals grown by directed crystallization, the existence of Tl₂Te as a distinct compound with a monoclinic lattice (space group C2/c (№15), a = 15.610 Å, b = 8.914 Å, c = 31.069 Å, β = 100.5°) was confirmed, in contrast to the tetragonal Tl₅Te₃ (space group I4/mcm (№140), a = 8.931 Å, c = 12.595 Å). A triangulation scheme for the Tl–Pb–Te system was constructed on the basis of an XRD analysis of samples that were annealed at 473 K. The existence of eight quasi-binary cross-sections was experimentally confirmed. The study of quasi-binary and partially quasi-binary phases allowed us to determine the nature of phase transitions, homogeneity boundaries, and non-variant equilibrium temperatures. It has been demonstrated that the ternary compound Tl₄PbTe₃ forms broad solid-solution regions with Tl₅Te₃ (over 85 mol%) and Tl₂Te (over 80 mol%). The constructed phase diagrams provide the physicochemical basis for the directed growth of high-quality single crystals with reproducible thermoelectric properties. Full article

(This article belongs to the Section Inorganic Solid-State Chemistry)

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19 pages, 7935 KB

Open AccessArticle

Catalytic Oxidation of Toluene over CoMnO_x/SBA-15 Catalyst: Promoting Effect of the Interaction Between Metal Active Components and the Support

by Jia Sun, Zhigang Liu, Meijun Sui, Yahui Wang, Peng Wang, Hongyu Zhu, Huali Yu and Hong Sun

Inorganics 2026, 14(9), 240; https://doi.org/10.3390/inorganics14090240 - 11 Sep 2026

Viewed by 454

Abstract

For supported catalysts, the interaction between metal active components and the support plays a crucial role in modifying catalyst properties, such as active sites and oxygen vacancies. Herein, a series of CoMnO_x/SBA-15 (Santa Barbara Amorphous-15) catalysts were prepared for catalytic oxidation [...] Read more.

For supported catalysts, the interaction between metal active components and the support plays a crucial role in modifying catalyst properties, such as active sites and oxygen vacancies. Herein, a series of CoMnO_x/SBA-15 (Santa Barbara Amorphous-15) catalysts were prepared for catalytic oxidation of toluene, in which the support properties were tailored by varying the hydrothermal crystallization time. The results revealed that subtle changes in support properties could lead to modifications of the supported active component. CM-48 (crystallization time of 48 h) exhibited the optimal low-temperature activity with T₉₀ of 234 °C and good stability for the catalytic oxidation of toluene. The improved performance was attributed to the enhancement of redox properties, abundant oxygen vacancies, and high mobility of lattice oxygen species resulting from the strong interaction between the active components and the support. Furthermore, the reaction mechanism was explored via in situ DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy), confirming that both surface-adsorbed oxygen and lattice oxygen served as active oxygen species participating in toluene oxidation, with surface-adsorbed oxygen being particularly favorable for the consumption of key intermediates. This work will guide the design of supported catalysts in practical applications for eliminating VOCs. Full article

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17 pages, 1103 KB

Open AccessArticle

Ni(II) Complexes of 2-Imine-8-Hydroxyquinolines: Characterization, Albumin Binding and Cytotoxicity

by Sofia Marcão, Leonor Côrte-Real, Alice Alborghetti, Maël Dejoux, Gabriella Spengler, Xavier Fontrodona, Isabel Romero, Éva A. Enyedy, Alexandra M. M. Antunes and Isabel Correia

Inorganics 2026, 14(9), 239; https://doi.org/10.3390/inorganics14090239 - 10 Sep 2026

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Abstract

Nickel(II) offers an appealing base for metallodrug design as it is abundant, inexpensive and forms well-defined complexes with N,O-donor ligands. Therefore, five Ni(II) complexes containing two tridentate 2-imine-8-hydroxyquinoline Schiff base ligands, derived from morpholine, piperidine, imidazole or 2-methyl-1H-limidazole, were synthesized and [...] Read more.

Nickel(II) offers an appealing base for metallodrug design as it is abundant, inexpensive and forms well-defined complexes with N,O-donor ligands. Therefore, five Ni(II) complexes containing two tridentate 2-imine-8-hydroxyquinoline Schiff base ligands, derived from morpholine, piperidine, imidazole or 2-methyl-1H-limidazole, were synthesized and characterized in solution and solid state via analytical and spectroscopic techniques. Single crystals were solved using X-ray diffraction for the complex derived from 4-(2-aminopropyl)morpholine (1). This Ni(II) complex exhibits a distorted octahedrally coordinated Ni(II) center bound to two monodeprotonated NNO-tridentate ligands, adopting a meridional coordination mode, with the two oxygen atoms arranged cis to each other. The stability of the complexes in aqueous media buffered at pH 7.4 was evaluated with UV–Vis spectroscopy and their binding to bovine serum albumin (BSA) was assessed with fluorescence titrations. All complexes show strong reversible binding to BSA (K_SV ~10⁵), which stabilizes the lipophilic complexes in aqueous media. The antiproliferative activity of the complexes was screened against colon cancer cell lines (Colo205 and Colo320). They exhibit moderate anticancer activity (IC₅₀ = 15.1–92.5 μM), with structure–activity relationships favoring imidazole derivatives and maintaining activity against the doxorubicin-resistant cell line (Colo320) with resistance indices (1.3–3.1) comparable to or lower than doxorubicin. Overall, the complexes represent a platform to develop new anticancer Ni-based drugs. Full article

(This article belongs to the Special Issue Feature Papers in Bioinorganic Chemistry 2026)

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13 pages, 1982 KB

Open AccessArticle

Mechanochemical Reduction of V₂O₅: Alkali Metals vs. Alkali Metal Hydrides—Which Are the More Suitable Reducing Agents?

by Anna Michaely and Guido Kickelbick

Inorganics 2026, 14(9), 238; https://doi.org/10.3390/inorganics14090238 - 9 Sep 2026

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Abstract

Vanadium oxides and alkali metal vanadates are promising electrode materials for electrochemical energy storage owing to their ability to access multiple oxidation states. In this study, mechanochemical reduction of V₂O₅ with alkali metal hydrides is explored as a facile route [...] Read more.

Vanadium oxides and alkali metal vanadates are promising electrode materials for electrochemical energy storage owing to their ability to access multiple oxidation states. In this study, mechanochemical reduction of V₂O₅ with alkali metal hydrides is explored as a facile route to obtain reduced vanadium oxide phases. Sodium hydride enables the rapid formation of mixed sodium vanadium oxide phases at room temperature, proceeding in a self-propagating manner after only a short milling period. To assess the generality of this approach, lithium hydride was evaluated as an alternative reducing agent and exhibited comparable reaction behavior and product distributions. Complementary theoretical calculations indicate that the corresponding reductions with elemental sodium and lithium are thermodynamically more favorable, displaying lower reaction enthalpies. This prediction is experimentally corroborated by the instantaneous ignition observed when elemental metals are used. Rietveld refinement reveals that all investigated reducing agents follow similar reaction pathways, yielding comparable mixtures of alkali metal vanadium oxides with consistent main phases. However, the use of highly ductile sodium metal results in significant mixing limitations, which can be mitigated only through cryogenic milling. These findings highlight mechanochemical reduction with alkali metal hydrides as a robust and practical strategy, particularly for systems in which metal ductility limits process efficiency, despite the associated risk of hydrogen evolution. Full article

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20 pages, 4765 KB

Open AccessArticle

Light-Induced Cu⁺ Active Sites on 2D Conductive MOF for Enhanced Photocatalytic H₂O₂ Generation

by Qi Guo, Pan Hou, Jingjie Cao, Hui Liu and Ge Tian

Inorganics 2026, 14(9), 237; https://doi.org/10.3390/inorganics14090237 - 8 Sep 2026

Viewed by 484

Abstract

The selective photocatalytic reduction of O₂ to H₂O₂ is an attractive route for sustainable H₂O₂ synthesis, yet its efficiency is often limited by the sluggish charge separation and insufficient selectivity of the two-electron oxygen reduction reaction. [...] Read more.

The selective photocatalytic reduction of O₂ to H₂O₂ is an attractive route for sustainable H₂O₂ synthesis, yet its efficiency is often limited by the sluggish charge separation and insufficient selectivity of the two-electron oxygen reduction reaction. Here, we develop a conductive 2D Cu₃(HHTP)₂ metal–organic framework (MOF) in which Cu²⁺ sites serve as dynamic redox centers to regulate interfacial electron transfer and O₂ activation. Upon photoexcitation, photogenerated electrons are preferentially transferred to Cu centers, inducing reversible reconstruction of the local Cu coordination environment. Benefiting from the extended π-conjugated framework and strong interlayer electronic coupling, the accumulated electrons can delocalize over the 2D sheets, facilitating charge separation and suppressing electron–hole recombination. Spectroscopic and theoretical investigations further reveal that the dynamically reconstructed Cu sites promote O₂ adsorption and activation through electron donation from Cu d orbitals to O₂ antibonding states, thereby stabilizing the O₂⁻ intermediate and favoring the two-electron reduction pathway toward H₂O₂. As a result, the Cu₃(HHTP)₂ photocatalyst achieves an H₂O₂ evolution rate of 3910 μmol g⁻¹ h⁻¹ under visible-light irradiation. These findings demonstrate that dynamically regulated Cu electronic structures provide an effective strategy for coupling charge-carrier management with selective O₂ activation, offering a rational approach to the design of conductive 2D photocatalysts for efficient H₂O₂ photosynthesis. Full article

(This article belongs to the Special Issue Advances in Metal–Organic Frameworks and Their Composites)

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33 pages, 3982 KB

Open AccessReview

Metal Interactions of Psychoactive Nitrogen-Containing Compounds: Coordination Chemistry, Structural Features, and Biological Activity

by Dušan Dimić

Inorganics 2026, 14(9), 236; https://doi.org/10.3390/inorganics14090236 - 7 Sep 2026

Cited by 1 | Viewed by 579

Abstract

Psychoactive nitrogen-containing compounds represent a structurally diverse group of natural and synthetic molecules whose interactions with metal ions influence their physicochemical properties, biological activity, and analytical behavior. Although numerous studies have reported the synthesis of metal complexes, solution interactions, and metal-assisted analytical methods, [...] Read more.

Psychoactive nitrogen-containing compounds represent a structurally diverse group of natural and synthetic molecules whose interactions with metal ions influence their physicochemical properties, biological activity, and analytical behavior. Although numerous studies have reported the synthesis of metal complexes, solution interactions, and metal-assisted analytical methods, the available knowledge remains scattered across compound classes and has not been comprehensively evaluated. This review summarizes advances in the coordination chemistry of psychoactive nitrogen-containing compounds from ScienceDirect, Google Scholar, and the Cambridge Structural Database (CSD), emphasizing donor atoms, coordination modes, structural diversity, crystallographic characterization, spectroscopic and computational investigations, and the biological properties of the resulting metal complexes. The current literature demonstrates that metal complexation can alter molecular geometry, electronic structure, redox behavior, biomolecular recognition, and pharmacological activity, while also offering opportunities to develop compounds with enhanced antimicrobial, anticancer, antioxidant, and DNA-binding properties. By integrating coordination behavior, structural, and biological aspects within a single framework, this review highlights the central role of metal interactions in psychoactive compounds and identifies emerging opportunities to develop advanced analytical methodologies and functional metal-based systems. Full article

(This article belongs to the Special Issue Metal Complexes Containing Bioactive Ligands: Structure and Biological Evaluation, 2nd Edition)

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17 pages, 5424 KB

Open AccessArticle

Near-UV-Excitable Sm³⁺/Eu³⁺-Activated Na₃YB₈O₁₅ Red Phosphors with High Thermal Stability for LED Applications

by Zhengrong Xia, Rongqing Li, Fangfang Liu, Yue Tong, Wang Zhao, Mingjun Song and Weiwei Zhou

Inorganics 2026, 14(9), 235; https://doi.org/10.3390/inorganics14090235 - 4 Sep 2026

Viewed by 467

Abstract

Near-ultraviolet-excitable red phosphors with high thermal stability are desirable for phosphor-converted LED applications, including potential plant-lighting applications. Herein, Sm³⁺- and Eu³⁺-activated Na₃YB₈O₁₅ phosphors were synthesized by a high-temperature solid-state reaction. Among the investigated compositions, [...] Read more.

Near-ultraviolet-excitable red phosphors with high thermal stability are desirable for phosphor-converted LED applications, including potential plant-lighting applications. Herein, Sm³⁺- and Eu³⁺-activated Na₃YB₈O₁₅ phosphors were synthesized by a high-temperature solid-state reaction. Among the investigated compositions, the optimal activator contents were identified as x = 0.02 for Na₃YB₈O₁₅:xSm³⁺ and y = 0.70 for Na₃YB₈O₁₅:yEu³⁺, with concentration quenching in both series mainly governed by dipole–dipole interactions. In the Sm³⁺/Eu³⁺ co-doped phosphors, the emission color shifted from orange-red toward red as the Eu³⁺ content increased. At 433 K, the Sm³⁺-doped, Eu³⁺-doped, and Sm³⁺/Eu³⁺ co-doped samples retained 119.7%, 93.4%, and 102.3% of their room-temperature integrated emission intensities, respectively. The high thermal stability may be attributed to the structural characteristics of the host, its wide optical band gap, and the temperature-dependent redistribution of Stark and phonon-assisted emission components. A phosphor-converted LED fabricated using Na₃YB₈O₁₅:0.02Sm³⁺,0.01Eu³⁺ and a commercial 400–405 nm, 5 W near-UV LED chip produced multiband emission that partially overlapped with the absorption bands of both chlorophylls and the P_R and P_FR forms of phytochrome. These results suggest that Sm³⁺/Eu³⁺-activated Na₃YB₈O₁₅ is a promising thermally robust, spectrum-adjustable red phosphor for LED applications. Full article

(This article belongs to the Section Inorganic Materials)

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39 pages, 8499 KB

Open AccessArticle

Influence of Fe and Zn Loading and Calcination Temperature on Sol–Gel-Derived TiO₂ Photocatalysts for Food-Industry Effluent Treatment

by Luiz Eduardo Nochi Castro, Larissa Resende Matheus, Leonardo de Freitas Marinho, Giane Gonçalves Lenzi, Maria Eduarda Kounaris Fuziki, Lazaro Jose Gasparrini, Graciela Ines Bolzon de Muniz, Ney Pereira Mattoso Filho and Leda Maria Saragiotto Colpini

Inorganics 2026, 14(9), 234; https://doi.org/10.3390/inorganics14090234 - 4 Sep 2026

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Abstract

Fe/Zn-modified TiO₂ photocatalysts were synthesized by the sol–gel method to investigate the influence of Fe loading, Zn loading, and calcination temperature on the degradation of food-industry pollutants. A 2³ factorial design combined with Response Surface Methodology was employed to optimize the [...] Read more.

Fe/Zn-modified TiO₂ photocatalysts were synthesized by the sol–gel method to investigate the influence of Fe loading, Zn loading, and calcination temperature on the degradation of food-industry pollutants. A 2³ factorial design combined with Response Surface Methodology was employed to optimize the synthesis parameters. The catalysts were characterized by N₂ adsorption–desorption, SEM/EDS, X-ray diffraction coupled with Rietveld refinement and point of zero charge analyses. The materials exhibited mesoporous structures with type IV isotherms, while Fe/Zn modification altered the crystalline phase composition and surface charge of TiO₂. Low metal loading stabilized the anatase phase, whereas higher Fe contents promoted the formation of hematite and rutile. Photocatalytic performance was evaluated through the discoloration and degradation of Red 40 and Tartrazine under natural sunlight and the degradation of cheese whey under artificial irradiation. F10Z2-400 exhibited the highest activity toward Red 40 (99.85% discoloration and 77.02% COD removal), whereas T-400 showed the best performance for tartrazine (86.25% discoloration and 87.61% COD removal). For cheese whey, F10Z10-400 achieved the highest degradation (41.01% COD removal). Reactive-species scavenging indicated that hydroxyl radicals made the predominant contribution to the discoloration of both dyes, followed by superoxide radicals and photogenerated holes. Kinetic analyses indicated that the Behnajady–Modirshahla–Ghanbery model best described the degradation process. RSM identified calcination temperature as the most influential synthesis parameter and showed that the effects of Fe and Zn loading were pollutant-dependent. No single catalyst formulation provided the best performance for all evaluated matrices. Full article

(This article belongs to the Special Issue New Trends in Heterojunction Photocatalysts)

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21 pages, 14609 KB

Open AccessArticle

Comparative Study of FeBO₃ Crystalline Powders Prepared by Solution Technique and Their Magnetic Properties

by Jacob Pfund, Shuai Jiang, Volkan Ortalan, Nishamini Ruwanthika Jayasekara, Steven L. Suib, Michael Newburger and Menka Jain

Inorganics 2026, 14(9), 233; https://doi.org/10.3390/inorganics14090233 - 3 Sep 2026

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Abstract

Iron borate (FeBO₃) has emerged as a promising candidate for magneto-optical applications owing to its unique combination of weak ferromagnetism (canted antiferromagnetic ordering) near room temperature and optical transparency in the visible range. While the growth of high-quality single crystals is [...] Read more.

Iron borate (FeBO₃) has emerged as a promising candidate for magneto-optical applications owing to its unique combination of weak ferromagnetism (canted antiferromagnetic ordering) near room temperature and optical transparency in the visible range. While the growth of high-quality single crystals is well-established, the scalable synthesis of bulk polycrystalline FeBO₃ remains challenging, often hindered by the presence of impurity phases and inconsistent reproducibility. This work offers a comprehensive investigation into the synthesis of bulk FeBO₃ powder using combustion, solid-state, and flux growth approaches. The structural and magnetic properties of the resulting materials are compared, enabling a direct comparison of synthesis routes. Practical guidelines are provided for optimizing processing protocols to achieve phase-pure, highly reproducible FeBO₃, thereby advancing its integration into functional magneto-optical devices. Full article

(This article belongs to the Special Issue Design and Application of Magnetic Materials)

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17 pages, 4714 KB

Open AccessArticle

Two New Zinc(II) Complexes with Symmetric and Asymmetric 2,6-Diacetylpyridine–Aminoguanidine Schiff Bases: Synthesis, Crystal Structures, and Comparative Study

by Marijana S. Regojević, Valentina M. Vukobrat, Milica G. Bogdanović, Marko V. Rodić, Ivana Đ. Borišev, Berta Barta Holló and Mirjana M. Radanović

Inorganics 2026, 14(9), 232; https://doi.org/10.3390/inorganics14090232 - 2 Sep 2026

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Abstract

Novel compounds based on symmetric and asymmetric 2,6-diacetylpyridine (DAP) Schiff bases were synthesized. A new salt of the symmetric Schiff base 2,6-diacetylpyridine-bis(aminoguanidine), L¹∙3HCl∙2H₂O, and its zinc(II) complex, [Zn(L¹)(SCN)₂] (1), were prepared. By template [...] Read more.

Novel compounds based on symmetric and asymmetric 2,6-diacetylpyridine (DAP) Schiff bases were synthesized. A new salt of the symmetric Schiff base 2,6-diacetylpyridine-bis(aminoguanidine), L¹∙3HCl∙2H₂O, and its zinc(II) complex, [Zn(L¹)(SCN)₂] (1), were prepared. By template synthesis, the zinc(II) complex with an asymmetric DAP derivative containing aminoguanidine and thiosemicarbazide moieties (L²), [Zn(L²–H)Cl] (2), was obtained. All compounds were characterized by elemental analysis, FTIR spectroscopy, molar conductivity, thermogravimetric analysis, antioxidant activity measurements, and, for the complexes, SC-XRD. In 1, the first complex containing the Schiff base of DAP and aminoguanidine, the chelating ligand coordinates as a pentadentate N₅ donor through the pyridine, two azomethine, and two guanidine imino nitrogen atoms. Two SCN^– are coordinated through sulfur atoms, an uncommon coordination mode with zinc(II). In 2, the ligand acts as an N₃S tetradentate donor involving one azomethine, one hydrazine, the pyridine nitrogen, and thioamide sulfur atom. The chloride anion completes the coordination sphere. Thermal analysis demonstrated stepwise desolvation of the hydrated ligand, whereas the solvent-free complexes underwent continuous thermal decomposition with characteristic gaseous products. The ligand displayed considerable antioxidant activity, which was markedly diminished upon coordination. Full article

(This article belongs to the Special Issue Metal-Based Compounds: Relevance for the Biomedical Field, 3rd Edition)

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17 pages, 1361 KB

Open AccessArticle

Gallium and Indium Complexes with Bulky Pyridine-Bis(phenolate) Ligands: Synthesis, Structure, and Activity in Ring-Opening Polymerization of Cyclic Esters

by Valeriia A. Serova, Badma N. Mankaev, Kamella R. Teplova, Konstantin A. Lyssenko, Alexander V. Kutchin and Sergey S. Karlov

Inorganics 2026, 14(9), 231; https://doi.org/10.3390/inorganics14090231 - 1 Sep 2026

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Abstract

A series of gallium and indium complexes bearing pyridine-2,6-bis(phenolate) ligands with ortho-substituents of increasing steric bulk (^tBu, SiMe₃, SiPh₃) was synthesized via SiMe₄ elimination from M(CH₂SiMe₃)₃ (M = Ga, In). [...] Read more.

A series of gallium and indium complexes bearing pyridine-2,6-bis(phenolate) ligands with ortho-substituents of increasing steric bulk (^tBu, SiMe₃, SiPh₃) was synthesized via SiMe₄ elimination from M(CH₂SiMe₃)₃ (M = Ga, In). The gallium complexes 2a–c were structurally characterized by X-ray diffraction, revealing monomeric four-coordinate distorted trigonal pyramidal geometries. DOSY NMR studies revealed that the indium complexes 3a (^tBu) and 3b (SiMe₃) are dimeric in solution, whereas the bulkier 3c (SiPh₃) is monomeric. All complexes were tested as initiators for ring-opening polymerization (ROP) of ε-caprolactone, L-lactide, and rac-lactide in the presence of benzyl alcohol. The M-CH₂SiMe₃ bond is inert toward alcohols, pointing to an activated monomer mechanism. Indium complexes exhibited higher activity than their gallium analogues, and the activity strongly depends on the ligand steric bulk: the most hindered SiPh₃ derivative 3c showed the highest activity, reaching full ε-CL conversion in 24 h at 80 °C, whereas the analogous gallium complex 2c was almost inactive. Full article

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14 pages, 34377 KB

Open AccessReview

Nanoindentation-Derived Mechanical Properties of Cubic III-Nitrides on MgO(001)-Based Templates: c-GaN, c-In_xGa_1−xN, and c-InN

by Esteban Cruz-Hernández, Edgar López-Luna and Miguel A. Vidal

Inorganics 2026, 14(9), 230; https://doi.org/10.3390/inorganics14090230 - 27 Aug 2026

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Abstract

Mechanical reliability is an essential prerequisite for III-nitride thin films throughout device fabrication and processing. However, the availability of nanoindentation data for metastable cubic phases remains limited, making cross-study comparisons particularly challenging. In this context, the present work offers a unified compilation of [...] Read more.

Mechanical reliability is an essential prerequisite for III-nitride thin films throughout device fabrication and processing. However, the availability of nanoindentation data for metastable cubic phases remains limited, making cross-study comparisons particularly challenging. In this context, the present work offers a unified compilation of hardness (H) and Young’s modulus (E) values derived from nanoindentation of cubic epilayers grown by plasma-assisted molecular beam epitaxy (MBE) on MgO(001)-based templates, encompassing c-GaN, c-In_x

{Ga}_{1 - x}

N alloys (

x = 0.26

–0.72), and c-InN. The three underlying studies utilize consistent metrological approaches: Berkovich indentation with Oliver–Pharr analysis, polished surfaces exhibiting low root-mean-square (RMS) roughness, and a shared MgO/c-GaN-templated stack. This methodological alignment enables a composition-aware comparison across the c-GaN/c-In_x

{Ga}_{1 - x}

N/c-InN series. Consolidated H and E values are examined as functions of the indium fraction, x, while their depth dependence is used to distinguish the film-dominated response from the increasing influence of the template or substrate. Additionally, a focused comparison with representative wurtzite data situates the cubic results within a broader context, while maintaining emphasis on MgO-based heteroepitaxy. Ultimately, the resulting dataset and analysis provide a practical resource for mechanically informed processing and reliability evaluation in cubic III-nitride systems. Full article

(This article belongs to the Special Issue Advanced Inorganic Semiconductor Materials, 4th Edition)

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16 pages, 8520 KB

Open AccessArticle

Mechanochemical Synthesis, Electronic Structure, and Photovoltaic Potential of Lead-Free Hybrid Halocobaltates (CH₃NH₃)₂CoX₄ (X = Cl, Br)

by Pablo Garrido, Karem Gallardo and Rodrigo Castillo

Inorganics 2026, 14(9), 229; https://doi.org/10.3390/inorganics14090229 - 26 Aug 2026

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Abstract

Here, (CH₃NH₃)₂CoCl₄ and (CH₃NH₃)₂CoBr₄ were prepared via a solvent-free mechanochemical route and characterized by powder X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, magnetic susceptibility, and thermal analysis. Both compounds [...] Read more.

Here, (CH₃NH₃)₂CoCl₄ and (CH₃NH₃)₂CoBr₄ were prepared via a solvent-free mechanochemical route and characterized by powder X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, magnetic susceptibility, and thermal analysis. Both compounds crystallize in the monoclinic P2₁/c space group and exhibit paramagnetic behavior consistent with isolated high-spin Co²⁺ tetrahedra and negligible inter-site exchange. Diffuse reflectance spectroscopy yielded optical band gaps of 1.65 and 1.60 eV for the chloride and bromide, respectively. Valence-band XPS and cyclic voltammetry provided consistent experimental band-edge positions, confirming favorable alignment with TiO₂ and Spiro-OMeTAD in an n-i-p architecture. SCAPS-1D simulations using experimentally determined optical and electronic parameters predicted power conversion efficiencies of 6.63% and 4.86%, at an optimum absorber thickness of 1.28 μm. Defect density was identified as the dominant performance-limiting parameter, while the parity-forbidden Co²⁺ d-d transitions intrinsically constrain the attainable photocurrent. These results provide the first experimental grounded photovoltaic assessment of hybrid halocobaltates, combining measured optical and electronic parameters with SCAPS-1D device simulations, and establish design parameters for future device optimization. Full article

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30 pages, 20146 KB

Open AccessArticle

Synergistic Defect Modification in Fe_x^II/Zn_1-xFe^III₂O₄ Nanostructures via Controlled Fe^II Doping (x = 0.0–0.4) for Enhanced Photocatalytic Crystal Violet Degradation

by Ebtsam K. Alenezy, Nady Hashem and Ibraheem O. Ali

Inorganics 2026, 14(9), 228; https://doi.org/10.3390/inorganics14090228 - 26 Aug 2026

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Abstract

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye [...] Read more.

Fe^II-doped zinc ferrite nanocrystals (Fe^II_xZn_1-xFe^III₂O₄) were prepared via a sol–gel approach in the presence of polyvinyl alcohol as a stabilizer and assessed for their capability to eliminate crystal violet (CV) dye from water-based solutions. The structural and surface characteristics of the prepared materials were examined by XRD, HRTEM, FESEM, ATR–FTIR, XPS, UV–visible spectrophotometer and BET analyses. XRD patterns confirmed the formation of a cubic spinel ferrite structure (Fd-3m), indicating successful incorporation of Fe^II into the ZnFe₂O₄ lattice. ATR–FTIR spectra showed characteristic metal–oxygen vibrations at the tetrahedral and octahedral sites. XPS analysis confirmed the coexistence of Fe^II and Fe^III species, which may promote interfacial charge transfer and redox reactions. HRTEM and FESEM images showed particle agglomeration and grain growth after calcination at 700 °C. Fe^II_0.2Zn_0.8Fe^III₂O₄ exhibited the highest photocatalytic performance, achieving 97.2% degradation of CV under optimized conditions. The effects of contact time, catalyst dosage, initial dye concentration, and pH were systematically studied. The maximum removal efficiency was obtained at pH 10 using 0.075 g catalyst for 20 mg L⁻¹ CV solution within 40 min. Freundlich isotherm models exhibited the strongest correlation (R² = 0.918), pointing to multilayer adsorption occurring across a non-uniform nanoparticle surface. The Dubinin–Radushkevich analysis returned an adsorption energy of 3.01 kJ mol⁻¹, implying that physical forces predominantly control the adsorption mechanism. Kinetic investigations revealed a two-stage CV uptake pathway: fast initial binding at exterior surface sites, succeeded by a slower migration of dye molecules into the internal pores of the adsorbent. Full article

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22 pages, 5150 KB

Open AccessArticle

Interfacial Charge-Transfer Engineering in Rare-Earth-Modified ZnO/Nanoporous Cu Heterostructures for Simulated-Solar-Light Methyl Orange Degradation

by Hangning Wang, Rifath Bin Hossain, Yanling Yang and Fengxiang Qin

Inorganics 2026, 14(9), 227; https://doi.org/10.3390/inorganics14090227 - 26 Aug 2026

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Abstract

The development of simulated-solar-light photocatalysts for methyl orange (MO) removal is limited by insufficient light utilization, rapid photogenerated charge recombination, and restricted interfacial reaction sites. Here, vertically aligned ZnO nanorods on a conductive nanoporous Cu (NPCu) scaffold were modified with low-abundance RE-containing surface [...] Read more.

The development of simulated-solar-light photocatalysts for methyl orange (MO) removal is limited by insufficient light utilization, rapid photogenerated charge recombination, and restricted interfacial reaction sites. Here, vertically aligned ZnO nanorods on a conductive nanoporous Cu (NPCu) scaffold were modified with low-abundance RE-containing surface species (RE = Ce, Sm, Er, Tm, and Yb). The notation RE(OH)₃@ZnO/NPCu is retained solely as an operational sample identifier and does not constitute a crystallographic or stoichiometric phase assignment. XRD resolves the ZnO/NPCu framework, EDS confirms the local presence of RE, and XPS identifies RE-dependent oxidation state and surface oxygen environments; collectively, these measurements do not uniquely establish RE(OH)₃ or distinguish hydroxide from oxide, oxyhydroxide, and other hydroxylated/adsorbed surface configurations. The distinguishing feature is a controlled five-RE comparison on one common ZnO/NPCu architecture, together with separate evaluation of NPCu under H₂O₂-free and H₂O₂-assisted conditions. Across three independent H₂O₂-free runs, the Er-modified sample achieved 96.61 ± 0.30% MO degradation within 9 min with k_obs = 0.3930 ± 0.0071 min⁻¹. Dosage screening identified 20 μL of 40 wt% H₂O₂ in 20 mL MO solution (approximately 13.5 mM) as a practical plateau dosage. Photolysis, dark, NPCu/H₂O₂, and catalyst-removal controls support an additional solid-catalyst-dependent Cu-associated peroxide contribution while not excluding trace homogeneous reactions. Three independent cycling experiments and post-cycle SEM/XRD/EDS support operational durability, although quantitative metal leaching was not measured. Tauc, Mott–Schottky, EIS, temperature-dependent kinetic, and scavenger results are interpreted as comparative descriptors or indirect evidence rather than direct proof of intrinsic band gaps, atom-specific carrier densities, or a unique microscopic mechanism. The AI-assisted component is restricted to exploratory contextualization because reference-grouped validation shows poor out-of-reference generalization. The conclusions are confined to the tested MO system. Full article

(This article belongs to the Section Inorganic Materials)

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9 pages, 1311 KB

Open AccessArticle

Tilted Magnetic Structure and Enhanced Magnetic Anisotropy of Bilayer CrSBr Induced by Exchange Bias Effect

by Jie Yang, Chao Mao, Yining Yang, Liang Zha and Jinbo Yang

Inorganics 2026, 14(9), 226; https://doi.org/10.3390/inorganics14090226 - 24 Aug 2026

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Abstract

The exchange bias (EB) effect is widely used for stabilizing reference magnetic layers in traditional spintronic devices, yet the EB strength strongly depends on the interfacial quality. Van der Waals antiferromagnets provide an ideal physical platform to study the interfacial magnetic properties for [...] Read more.

The exchange bias (EB) effect is widely used for stabilizing reference magnetic layers in traditional spintronic devices, yet the EB strength strongly depends on the interfacial quality. Van der Waals antiferromagnets provide an ideal physical platform to study the interfacial magnetic properties for device design in the 2D limit. Herein, we construct CrSBr/Fe₃GeTe₂ heterostructures and investigate the interfacial coupling via first-principles calculations. The results reveal that robust EB coupling in the heterostructure breaks the intrinsic in-plane magnetic limitation of CrSBr, inducing a stable tilted magnetic structure with magnetic moments tilting toward the out-of-plane direction. Such EB-driven magnetic reconstruction dramatically boosts the perpendicular magnetic anisotropy energy to ~6.5 meV/Cr and increases the AFM-FM energy difference to 1.97 meV/f.u. from 0.32 meV/f.u., achieving simultaneous enhancement of magnetic anisotropy and thermodynamic stability. The transport simulations of the CrSBr/Fe₃GeTe₂-based magnetic tunnel junction demonstrate that ~65% TMR can be achieved with the use of such an EB-pinned reference layer. This work clarifies the EB modulation mechanism in 2D CrSBr/Fe₃GeTe₂ heterostructures and provides a reliable theoretical basis for the design of high-performance CrSBr-based reference layers in spintronic devices. Full article

(This article belongs to the Special Issue Inorganics Emerging Investigators Themed Collection)

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51 pages, 27669 KB

Open AccessReview

Recent Advances in Metal Oxide-Coated Anodes for Industrial Electrochemical Applications: Emphasis on RuO₂-and IrO₂-Based Systems, Failure Mechanisms, and Coating Technologies

by Guan-Ting Pan, Allan Kwang Loon Ang and Aleksandar N. Nikoloski

Inorganics 2026, 14(9), 225; https://doi.org/10.3390/inorganics14090225 - 24 Aug 2026

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Abstract

Anode materials play a pivotal role in a wide range of electrochemical applications, including electrolysis, energy storage, corrosion protection, and industrial oxidation processes. This review provides a comprehensive analysis of recent advances in anode materials, with particular emphasis on their structural characteristics and [...] Read more.

Anode materials play a pivotal role in a wide range of electrochemical applications, including electrolysis, energy storage, corrosion protection, and industrial oxidation processes. This review provides a comprehensive analysis of recent advances in anode materials, with particular emphasis on their structural characteristics and major preparation methods, including thermal decomposition, electrochemical deposition, sol–gel processing, and magnetron sputtering. The degradation behaviour of anodes under electrochemical operating conditions is also critically discussed, together with strategies for improving their durability and overall performance. Particular attention is given to metal oxide-coated anodes, especially those based on ruthenium oxide (RuO₂) and iridium oxide (IrO₂), which remain the most representative systems in dimensionally stable anode (DSA) research and industrial applications. Emerging coating materials, including Co₃O₄- and carbon-based catalysts, are also reviewed as promising alternatives for reducing noble metal usage while maintaining acceptable electrochemical performance. In addition, the role of intermediate layers in titanium-based anodes is examined, with emphasis on their contribution to coating adhesion, conductivity, interfacial stability, and long-term electrode performance. This review further discusses the applications of anode materials in chlorine- and oxygen-related electrochemical industries and evaluates the performance of DSAs in relation to substrate selection, coating composition, and operational requirements. Alternative furnace technologies for anode baking are also reviewed, including conventional furnace heating, laser heating, and microwave heating, together with representative industrial furnace systems such as muffle, continuous, and vacuum furnaces. Overall, this review provides an integrated overview of the current progress in anode material research and development, while highlighting the key challenges and future directions for improving anode efficiency, durability, and sustainability in industrial electrochemical applications. Full article

(This article belongs to the Section Inorganic Materials)

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16 pages, 14150 KB

Open AccessArticle

Effects of Sn Doping on Charge Transport and Thermoelectric Performance of Wittichenite

by Do Hyeon Lee and Il-Ho Kim

Inorganics 2026, 14(9), 224; https://doi.org/10.3390/inorganics14090224 - 23 Aug 2026

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Abstract

Wittichenite Cu₃BiS₃ is a promising thermoelectric material with intrinsically low thermal conductivity owing to its complex crystal structure and strong lattice anharmonicity; however, its thermoelectric performance is limited by low carrier concentration and insufficient electrical conductivity. In this study, Cu [...] Read more.

Wittichenite Cu₃BiS₃ is a promising thermoelectric material with intrinsically low thermal conductivity owing to its complex crystal structure and strong lattice anharmonicity; however, its thermoelectric performance is limited by low carrier concentration and insufficient electrical conductivity. In this study, Cu₃Bi_1−xSn_xS₃ (x = 0.02–0.06) compositions were designed by substituting Sn⁴⁺ for Bi³⁺ sites, and dense single-phase bulk specimens were prepared using mechanical alloying followed by hot pressing. The effects of Sn doping on charge transport and thermoelectric properties were then systematically examined. Structural analysis confirmed that Sn was successfully incorporated into the Cu₃BiS₃ lattice without secondary phase formation, accompanied by anisotropic lattice contraction associated with the difference in ionic radii between Sn⁴⁺ and Bi³⁺. With increasing Sn content, the carrier concentration increased from approximately 10¹⁶ cm⁻³ to the 10¹⁷ cm⁻³ level, whereas the Hall mobility remained nearly unchanged, resulting in a substantial enhancement in electrical conductivity. Although the Seebeck coefficient decreased with increasing carrier concentration, the reduction was moderate, leading to an improved power factor of 0.10 mW·m⁻¹·K⁻² at 673 K. The thermal conductivity remained low, approximately 0.30–0.40 W·m⁻¹·K⁻¹, across the entire composition range, and the electronic contribution was less than 1%, indicating that heat transport was predominantly governed by the lattice contribution. These results demonstrate that Sn doping effectively improves the electrical transport properties while preserving the intrinsically low lattice thermal conductivity of Cu₃BiS₃. Consequently, a maximum ZT of 0.18 was achieved at 673 K, corresponding to a 64% improvement compared with the undoped specimen. Therefore, this study suggests that carrier concentration control via aliovalent doping is an effective strategy for enhancing the thermoelectric performance of wittichenite. Full article

(This article belongs to the Special Issue Advances in Thermoelectric Materials, 2nd Edition)

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20 pages, 7443 KB

Open AccessArticle

2,2′-Azobisphenolate Ligand Bearing Electron-Donating Methoxy Substituents: Spin-Crossover Ligand Field for a Fe(III) Complex and Stabilization of Ligand-Centered Oxidation Species Due to Its Resonance Effect

by Kazuyuki Takahashi, Taisei Kasazaki, Shogo Tsuchiya, Keiji Ueda, Atsuhiro Miyawaki, Suguru Murata, Takahiro Sakurai, Hitoshi Ohta and Toshiyuki Osakai

Inorganics 2026, 14(9), 223; https://doi.org/10.3390/inorganics14090223 - 23 Aug 2026

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Abstract

To investigate the electron-donating substitution effect on spin crossover (SCO) and electrochemical behaviors for homoleptic trivalent metal complexes with 2,2′-azobisphenolate (azp) ligands, the known 2,2′-azobisphenol with 5,5′-dimethyoxy substituents (H₂L^OMe) was synthesized and characterized by NMR spectroscopy and single-crystal X-ray [...] Read more.

To investigate the electron-donating substitution effect on spin crossover (SCO) and electrochemical behaviors for homoleptic trivalent metal complexes with 2,2′-azobisphenolate (azp) ligands, the known 2,2′-azobisphenol with 5,5′-dimethyoxy substituents (H₂L^OMe) was synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction (SCXRD). The homoleptic Fe^III and Al^III complexes 1-OMe and 2-OMe were prepared along with the homoleptic Fe^III complex with 5,5′-dimethyl-substituted azp ligands 1-Me. The temperature dependence of magnetic susceptibility and SCXRD revealed that 1-OMe exhibits incomplete gradual SCO with the rotational motion of the ligands. Cyclic voltammograms and their simulations revealed that both the Fe^III complex 1-OMe and the Al^III complex 2-OMe exhibit reversible one-electron oxidation waves, indicating that the introduction of the methoxy group enhances the stability of the oxidized species of the complexes. DFT calculations revealed that the oxidation waves for both the Fe^III and Al^III complexes are ligand-centered, while the reduction wave for the Fe^III complexes 1-OMe and 1-Me is metal-centered. In addition, the stability of the oxidized complex species arises from the resonance effect of the methoxy group. Full article

(This article belongs to the Section Coordination Chemistry)

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