Development of a 3d local crystal structure analysis method using electron nano-probe and its application to relaxors

2020 Fiscal Year Final Research Report

• Project/Area Number: 18H03674
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 13:Condensed matter physics and related fields
• Research Institution: Tohoku University
• Principal Investigator: Tsuda Kenji 東北大学, 学際科学フロンティア研究所, 教授 (00241274)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 局所結晶構造解析 / 収束電子回折 / ナノ電子プローブ / 機械学習 / リラクサー

Outline of Final Research Achievements

In order to develop a 3-dimensional local structure analysis method using an electron nano-probe, a new system was developed to map energy-filtered convergent-beam electron diffraction (CBED) data with a high speed and a high angular resolution. Deep neural network was successfully applied for accelerating dynamical diffraction intensity calculations of large-angle CBED (LACBED) patterns. For obtaining structural information in depth-direction, the scattering matrix method was implemented in our dynamical diffraction simulation code MBFIT for describing distribution of local structures in the electron beam direction. This newly developed analysis method was applied to local crystal structure analysis of a ferroelectric twin boundary in CaTiO3, visualization of ferroaxial domains in NiTiO3, electrostatic potential and electron density analysis of quantum paraelectric phase of KTaO3, local structure analysis of relaxor-like nano-domains in BaTiO3 under applying electric field.

Free Research Field

電子線結晶学

Academic Significance and Societal Importance of the Research Achievements

結晶構造は材料開発の基礎となる重要な情報であるが、近年、大きな領域の平均の結晶構造ではなく、局所的な結晶構造とその不均一性が新奇物性の起源となっている例が増加している。このような試料の解析には、ナノメーター （=10億分の1 m）に絞った電子線（ナノ電子プローブ）を使う方法が威力を発揮する。本研究ではナノ電子プローブを用いて局所結晶構造とその3次元分布を定量的に調べる新たな方法を開発し、種々の物質の局所結晶構造解析に適用して、ナノ電子プローブによる局所結晶構造解析法の適用範囲を大きく拡げた。