Anion chemistry unlocks new functionality

Mixed-anion compounds, incorporating two or more types of anionic species, such as oxides, nitrides, halides, sulfides, or hydrides, represent an emerging class of functional materials in solid state chemistry. The coexistence of different anions within a single lattice enables precise modulation of crystal symmetry, coordination environment, and electronic band structures, unlocking new physicochemical properties unattainable in single-anion systems. For instance, transition metal oxynitrides combine oxide and nitride anions coordinated to metal cations, where the introduction of N 2p orbitals into the valence band hybridizes with O 2p orbitals, resulting in band-gap narrowing and enhanced visible light absorption. Similarly, metal oxyhalides exhibit adjustable halogen composition, allowing fine-tuning of band edge positions, optical transitions, and charge-transport behavior. Their intrinsic electric dipole moments and defect-tolerant structures further facilitate efficient charge separation and reduced electron-hole recombination, rendering them highly promising for solar-driven photocatalytic processes. In our research lab, we aim to synthesize novel mixed-anion compounds, particularly oxynitrides, oxysulfides, and oxyhalides, develop innovative synthetic strategies, elucidate their crystal structures via X-ray, synchrotron, and neutron diffraction techniques, and investigate their structure-property relationships for sustainable energy and environmental applications.

Relevant Publications

[1] M. Hojamberdiev, R. Vargas, L. Madriz, D. Nematov, U. Shaislamov, H. Wagata, Y. Kubota, K. Yubuta, K. Teshima, and N. Matsushita, Selective Synthesis of β-TaON: The Critical Influence of Oxygen Partial Pressure in Ammonolysis, Dalton Transactions, 2025, 54, 11193–11206.
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[2] M. Hojamberdiev, R. Vargas, F. Zhang, K. Teshima, and M. Lerch, Perovskite BaTaO₂N: From Materials Synthesis to Solar Water Splitting, Advanced Science, 2023, 10, 2305179.
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[3] M. Hojamberdiev, A. Yamaguchi, K. Yubuta, S. Oishi, and K. Teshima, Fabrication of La₂Ti₂O₇ Crystals Using an Alkali Metal Molybdate Flux Growth Method and Their Nitridability to Form LaTiO₂N Crystals under a High-Temperature NH₃ Atmosphere, Inorganic Chemistry, 2015, 54, 3237–3244.
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[4] M. Hojamberdiev, J. M. Mora-Hernandez, R. Vargas, A. Yamakata, K. Yubuta, E.M. Heppke, L.M. Torres-Martínez, K. Teshima and M. Lerch, Time-retrenched synthesis of BaTaO₂N by localizing an NH₃ delivery system for visible-light-driven photoelectrochemical water oxidation at neutral pH: Solid-state reaction or flux method? ACS Applied Energy Materials, 2021, 4, 9315–9327.
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