研究者氏名職位 Kenji TSUDA Associate Professor 東北大学多元物質科学研究所 Institute of Multidisciplinary Research for Advanced Materials Tohoku University 先端計測開発センター電子回折・分光計測研究分野 Division of Electron Crystallography and Spectroscopy, Center for Advanced Microscopy and Spectroscopy         収束電子回折局所結晶構造・静電ポテンシャル分布解析構造相転移強誘電体 Convergent-beam electron diffraction Local crystal structure and electrostatic potential analysis Structural phase transition ferroelectrics 収束電子回折法による局所結晶構造・静電ポテンシャル分布解析法の開発と応用 Development of local crystal structure and electrostatic potential analysis method using convergent-beam electron diffraction and its applications ナノ粒子・ドメイン境界・界面など，ナノスケールの局所構造に起因する物性が近年注目されています．このような物性の起源を調べるためには，従来の放射光 X 線・中性子回折による結晶構造解析では不可能な，ナノスケール空間分解能での局所構造解析法が必要です．ナノサイズの電子プローブを用いる収束電子回折 (CBED) 法によれば，このような局所構造解析を実現することができます． Novel physical properties caused by nanoscale local structures, such as nano-particles, domain boundaries and interfaces, are increasingly attracting interest. To investigate their mechanisms, a local crystal structure analysis method with a nanoscale spatial resolution not accessible by SR X-ray and neutron diffraction. Such a local structure analysis can be realized by convergent-beam electron diffraction (CBED) with a sub-nanometer electron probe. われわれは，CBED 法を用いたナノスケール局所結晶構造・静電ポテンシャル分布解析法の開発を行っています．この方法を用いて，ナノスケールの局所構造物性研究を開拓します．強誘電体の構造相転移における局所構造揺らぎの変化，強誘電ドメイン境界や強誘電ナノ粒子の局所構造などの解析を進めています． We have been developing a nanoscale local crystal structure and electrostatic potential analysis method using CBED. We aim to develop the field of nanoscale local structure physics using the method. Analyses of nanoscale local structural fluctuations in the phase transitions of ferroelectrics, local structure analyses of ferroelectric domain boundaries and ferroelectric nano-particles are in progress. Fig.1. Electron-density isosurface of silicon determined by CBED, which is colored with electrostatic potential (red for lowest and blue for highest) Fig.2. Schematic diagram of the combined method of scanning transmission electron microscopy and convergent-beam electron diffraction (STEM-CBED) Fig.3. STEM-CBED map of the ferroelectric tetragonal phase of BaTiO3. The directions of local polarizations are expressed by arrows. Phys. Rev. B 86, 214106 (2012). Appl. Phys. Lett. 102, 051913 (2013). Appl. Phys. Lett. 103, 082908 (2013). Appl. Phys. Express 6, 101501 (2013). Nature Materials 12, 1024 (2013). 日本結晶学会誌 56, 98 (2014). [email protected] http://www.tagen.tohoku.ac.jp/labo/terauchi/