HOME > Profile > TSUJIMOTO, Yoshihiro
- Address
- 305-0044 1-1 Namiki Tsukuba Ibaraki JAPAN [Access]
Accepting Students
External affiliations
- 北海道大学 総合化学院 物質化学コース 客員准教授 (NIMS連携大学院)
Research
- Keywords
Exploration of new functional materials by mixed-anion lattice engineering
PublicationsNIMS affiliated publications since 2004.
Published patent applications
Society memberships
The Ceramics Society of Japan , The Physical Society of Japan
Funds
- 池谷科学技術振興財団 (2025)
- 大倉和親記念財団 (2025)
- 住友財団 (2023)
- 村田学術振興財団 (2022)
Research Center for Materials Nanoarchitectonics (MANA)
Exploration of New Functional Mixed-Anion Materials
mixed-anion materials, ion-conductiong materials, crystal growth, high-pressure synthesis, second-harmonic generation, low-dimensional magnetism
Overview
Many of the materials used in existing scientific and technological foundations consist of compounds with a single anion species, such as oxides and nitrides. In recent years, intensive research has focused on combining multiple anions with markedly different physical and chemical characteristics to enhance the functionality of known materials or to realize entirely new properties. In this study, we synthesize new compounds—primarily oxychalcogenides and oxyhalides—using high‑pressure synthesis, low‑temperature synthesis, and flux methods. We further evaluate their functional and physical properties, with particular emphasis on ionic conductivity, nonlinear optical responses, and low‑dimensional magnetism.
Novelty and originality
● By integrating oxygen and halogen anions, we successfully modulated the coordination geometry and coordination number of transition‑metal cations, thereby achieving control over their magnetic ground states.
●We discovered, for the first time in an inorganic solid, a pressure‑induced spin‑transition phenomenon in Sr₂CoO₃F, accompanied by a structural change in the cobalt coordination environment from five‑fold to six‑fold coordination.
● We discovered two new ultraviolet nonlinear optical oxysulfides containing chalcogen elements, La₃Ga₃Ge₂S₃O₁₀ and SrZn₂S₂O.
Details
(i) Mixed‑anion compounds are generally less stable than single‑anion compounds, and even when they can be synthesized, phase identification is often challenging. In this study, we explore new materials by employing high‑pressure synthesis, low‑temperature solid‑state reactions, and flux methods capable of producing single crystals, all of which are effective for synthesizing mixed‑anion compounds.
(ii) Sr₂NiO₃X (X = Cl, F) is a low‑dimensional magnetic material featuring two‑dimensionally arranged NiO₂ planes. Low‑spin Ni³⁺ adopts a square‑pyramidal coordination with five oxygen atoms. The ordering of halogen atoms occupying the apical sites differs between the Cl and F analogues, and this variation influences the magnetic ground state.
(iii) Chalcogenide compounds are used as nonlinear optical materials for infrared applications. In this study, to apply the large polarizability of chalcogen elements to ultraviolet applications, we are exploring new oxychalcogenide compounds that possess short absorption‑edge wavelengths and large nonlinear optical coefficients through mixed‑anion design combining oxygen and chalcogen elements.
Summary
Research on mixed‑anion compounds has a much shorter history than that on single‑anion compounds, and the number of known examples remains extremely limited. Nevertheless, the emergence of outstanding functional materials—such as SiAlON phosphors—demonstrates that mixed‑anion compounds hold great potential for exhibiting properties surpassing those of conventional materials. In this study, we aim to develop new model compounds with an eye toward future practical applications.
