Investigation of atomistic solute segregation at ceramic grain boundaries

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K13982
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 26010:Metallic material properties-related
• Research Institution: The University of Tokyo
• Principal Investigator: Feng Bin 東京大学, 大学院工学系研究科(工学部), 特任准教授 (20811889)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 粒界溶質偏析 / 原子分解能電子顕微鏡 / イットリア安定化ジルコニア / STEM―EDS

Outline of Final Research Achievements

In this study, we aim to reveal the atomistic mechanisms of solute segregation at ceramic grain boundaries (GBs) using Yttria-stabilized zirconia (YSZ) as model materials. We have systematically fabricated different types of symmetric, asymmetric and small angle tilt YSZ GBs using bicrystal method, and the atomistic GB segregation structures were observed by atomic resolution STEM-EDS. It was found that Y segregated at all GBs, while O segregated at most of the GBs. Furthermore, atomistic GB segregation structures were confirmed. These results suggest that the GB solute segregations are mainly dominated by the long-range electric interactions between charged GB core and charged point defects, while elastic strain also affects the Y segregation in the GB.

Free Research Field

材料科学

Academic Significance and Societal Importance of the Research Achievements

粒界溶質偏析現象は実用セラミックス材料中に普遍的に存在している現象であり、材料やデバイスの巨視的な特性に大きな影響を及ぼしているが、その本質的なメカニズムは不明であった．本研究では粒界溶質偏析構造を原子レベルで直接観察することにより、電気的相互作用が粒界溶質偏析の主な駆動力であることを明らかにした．本結果は粒界溶質偏析メカニズムを解明したものであり、学術的に重要な成果であると考えられる．さらに今後、粒界溶質偏析制御に基づいた新規セラミックスの開発にもつながることが期待される．