Boron isotope enriched high thermal conductivity boron arsenide

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K21162
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 31:Nuclear engineering, earth resources engineering, energy engineering, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Kurosaki Ken 京都大学, 複合原子力科学研究所, 教授 (90304021)
• Co-Investigator(Kenkyū-buntansha): 大石 佑治 大阪大学, 大学院工学研究科, 准教授 (20571558)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: ヒ化ホウ素 / ホウ化シリコン / 熱伝導率

Outline of Final Research Achievements

The thermal conductivities of boron arsenide and silicon boride were studied. In particular, we focused on the correlation between the boron isotope ratio and the thermal conductivity. In collaboration with overseas researchers, we have attempted to synthesize boron arsenide, but due to experimental difficulties caused by the toxicity of arsenic, we were able to synthesize a small amount of samples, but were unable to handle a large enough amount to evaluate the physical properties. On the other hand, regarding silicon boride, we succeeded in synthesizing a compound of silicon and boron 1;6 (SiB6), and through comprehensive evaluation of the basic physical properties of SiB6, we found that SiB6 is a strange material that combines low thermal conductivity with high hardness.

Free Research Field

材料科学

Academic Significance and Societal Importance of the Research Achievements

今回、当初は高熱伝導率材料として期待されているヒ化ホウ素に着目して研究を開始したが、思わぬところからホウ化シリコン（SiB6）の特異物性を発見することができた。具体的には、SiB6が非常に高い硬度と低い熱伝導率を併せ持つことを見出した。SiB6において、その極端に複雑な結晶構造とナノスケールで材料中に高密度に形成される欠陥により、通常はトレードオフの関係にある高い強度と低い熱伝導率が同時に発現した。この特異な特徴をいかして、機械的強度が優れた断熱材料や熱電材料といった機能性材料への応用が期待できる。