New synthesis route for isotope controlled boron nitride crystals and their properties

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K19136
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 36:Inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: National Institute for Materials Science
• Principal Investigator: TANIGUCHI Takashi 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点, フェロー (80354413)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 窒化ホウ素 / 高圧合成 / 同位体濃縮 / 複分解反応

Outline of Final Research Achievements

Boron nitride crystals are known for low density hexagonal form (hBN) and high density cubic form (cBN). Although they have been applied in industry, effect of their isotope enrichment is still subject of study for exploring new functions. Metathesis reaction between boride and nitride compound near 3-5GPa region was successfully resulted in synthesis of isotopically pure hBN and cBN crystals. Linear relationship between Raman shit and their reduced mass was observed as an evidence of clear isotope effect. 10B and 11B enriched cBN crystals exhibit near two time increase of thermal conductivity at room temperature.

Free Research Field

高圧合成　超硬質材料　半導体材料

Academic Significance and Societal Importance of the Research Achievements

窒化ホウ素（BN）結晶において低密度の六方晶 (hBN)と高密度の立方晶 (cBN)結晶のホウ素同位体濃縮とその効果を明らかにすることを目的とした。優れた耐熱材、或いは超硬質材料であるhBN及びcBN結晶はワイドギャップ半導体としても優れた特性が期待されているが、そのホウ素同位体濃縮効果が興味深い。炭素の同位体効果が多角的に研究されているのに対して、窒化ホウ素(BN)結晶中のホウ素及び窒素同位体濃縮効果の研究は未踏であった。本研究はBN結晶の新たな高圧合成経路を開拓し、ホウ素同位体(10B及び11B)組成を任意に制御したhBNとcBN高品位単結晶を合成し、その基礎物性を明らかにした。