Elucidation of Formation Mechanism of Morphotropic Phase Boundary of Relaxor Thin Films based on Frustration of Coexisting Phases

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H04118
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: Tohoku University
• Principal Investigator: Takanori Kiguchi 東北大学, 金属材料研究所, 准教授 (70311660)
• Co-Investigator(Kenkyū-buntansha): 嶋田 雄介 東北大学, 金属材料研究所, 助教 (20756572) ; 山田 智明 名古屋大学, 工学研究科, 准教授 (80509349) ; 佐藤 和久 大阪大学, 超高圧電子顕微鏡センター, 准教授 (70314424)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: リラクサー / 薄膜 / 歪み誘起相転移 / 組成相境界 / 弾性場 / 分極回転 / 電子顕微鏡 / 結合状態

Outline of Final Research Achievements

Relaxor ferroelectrics show many attractive electrical properties such as high dielectric constant, high piezoelectric constant, small temperature dependence, dielectric dispersion in the low frequency range, and electromechanical coupling factors at a composition around the morphotropic phase boundary (MPB). We have elucidated the MPB shift phenomena of relaxor and ferroelectric thin films from the viewpoint of the local strain field analysis and the nanoscale phase stability between the frustrating phases. The opposing forces between the thermal strain and the strain induced from the misfit dislocations complexly bias the stability of the frustrating pseudo cubic and tetragonal phases. Strictly, these phase act as the intermediate monoclinic phases, in which the spontaneous polarization can rotate easily between the two phases. Thus, the true nature of the characteristic morphology at a MPB composition of PMN-PT epitaxial thin films are strain induced monoclinic phases.

Free Research Field

無機材料物性、結晶構造、電子顕微鏡