Preparation of negative thermal expansion materials having two shrinkage mechanisms and evaluation of that heat shrinkage mechanism

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01618
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Isobe Toshihiro 東京工業大学, 物質理工学院, 准教授 (20518287)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 熱膨張 / 相転移 / 結晶構造解析 / 元素置換 / フィラー / コールドシンタリング

Outline of Final Research Achievements

In this study, the thermal shrinkage mechanism of Zr2SP2O12 was evaluated. And the thermal expansion performance of Zr2SP2O12 was enhanced. The shrinkage mechanism of Zr2SP2O12 was analyzed by crystal structure analysis using high temperature XRD. Thermal shrinkage according to the framework model was attributed to changes in the bond angle between ZrO6 and PO4 (or SO4), and thermal shrinkage according to the phase transition model was related to the distortion of the ZrO6 octahedron. These results suggested that element substitution at the Zr site is more effective than element substitution at the P(S) site. Based on the obtained knowledge, the several materials described by Zr2-xMxSP2O12 were synthesized. The maximum negative thermal expansion coefficient of the sample with the deformed MO6 octahedron was 1.5 times higher than that of the original Zr2SP2O12.

Free Research Field

無機材料工学

Academic Significance and Societal Importance of the Research Achievements

負熱膨張材料は、IoTや5Gなどに用いられるスマートデバイスに必要な材料である。代表者等が発見したZr2SP2O12は、負熱膨張材料の2大収縮メカニズムであるフレームワークモデル（広い温度域が特長）と相転移モデル（巨大な熱収縮が特長）を併せ持つ世界初の物質であり、その収縮メカニズムの解明は学術的に意義深い。また、メカニズムの解明に基づき、Zr2SP2O12を高性能化できれば、産業的にも重要な材料となる。実際に、本研究成果を元にした特許の出願や、本科研費に関連する研究で、民間企業への技術移転に成功したことから、社会への波及効果の高い研究といえる。