High-pressure synthesis of high-entropy chalcogenides with pyrite-type structure

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05450
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: Shibaura Institute of Technology
• Principal Investigator: Yamamoto Ayako 芝浦工業大学, 工学部, 教授 (50398898)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 高圧合成 / 高エントロピー / パイライト / 金属カルコゲナイド / 電気伝導 / 磁性 / 結晶構造

Outline of Final Research Achievements

Inspired by the high entropy effect (expected and unexpected changes in properties due to equimolar solid solutions of multiple elements), which has been reported to significantly improve functional properties in alloys, metal-sulfides and metal-selenides with a pyrite structure have been developed. Its' high entropy effect was verified. Metal sulfides and metal selenides containing equal amounts of four or more 3d4d transition metals were synthesized by a high-pressure synthesis method that suppresses volatilization of sulfur and selenium and allows rapid cooling from high temperatures. It was found that a uniform solid solution is formed when there is no significant difference in ion size. At the same time, the crystal structure, electrical conductivity, magnetism, etc. were investigated and compared with the parent material.

Free Research Field

無機化学

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的成果は、合金から始まった高エントロピー材料が基本的な組成MX2と代表的な結晶構造(パイライト型構造)をもつ硫化物やセレン化物に広がったことである。合成にあたっては、閉鎖系セルを用いて高揮発性の元素の蒸散を抑える高圧法が有効に機能した。一方で、社会的な意義としては、新しい元素の組み合わせの硫化物やセレン化物では、複数の酸化還元電位を同時に有することから、将来的には酸化および還元反応の触媒として機能することが期待される。