The behavior of residual hydrogen behavior and visualization of diffusion pathways in hydrogen storage materials by in situ neutron scattering

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12534
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 80040:Quantum beam science-related
• Research Institution: Ibaraki University
• Principal Investigator: Iwase Kenji 茨城大学, 理工学研究科(工学野), 准教授 (00524159)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 中性子回折 / Rietveld解析 / 水素貯蔵材料 / 拡散

Outline of Final Research Achievements

TiCrMo bcc solid solution alloy is unable to release all of the hydrogen absorbed in the first cycle, and some remains in the alloy. The amount of hydrogen remaining reaches about 40% of the maximum hydrogen capacity. Neutron diffraction experiments were performed during the absorption-desorption process. The structural change from the bcc structure to the CaF2-type structure with hydrogen absorption, and the occupation and amount of hydrogen remaining in the alloy during the structural change and in the alloy could be quantified. In the case of maximum hydrogen absorption, the CaF2-type structure is present and hydrogen occupies only the T site. In the case of residual hydrogen, the bcc structure is present and hydrogen occupies the T site. The distribution of metal atoms around the residual hydrogen was analyzed, and it was found that Ti was more abundantly distributed than Cr and Mo.

Free Research Field

材料工学

Academic Significance and Societal Importance of the Research Achievements

金属格子内のTiの配置を制御することが、残留水素の解消に繋がる。残留水素が占有されているTサイトを構成するTi,Cr,Moが均一に配置されることによって、残留水素量の減少が可能となると思われる。これまでアーク溶解を用いて、固溶体合金の合成を実施してきた。今回の研究成果から、アーク溶解以外の手法でTi,Cr,Moの配置を制御する合成方法を導入することによって、吸蔵放出特性の改善が可能となる。残留水素の解消によって、これまでの水素貯蔵材料の中で、繰り返し最大量の吸蔵放出が可能となることが期待される。この結果は、社会での水素インフラの普及過程において、水素貯蔵材料の活用に岐路を見出せたと考えられる。