The University of Tokyo

Advanced Industrial Science and Technology（AIST）

Japan Synchrotron Radiation Research Institute（JASRI）

Key achievements

・ The research group successfully captured the tilting motion of silver halide during X-ray photoreactions and the changes in the lattice structure of the formed silver at a frame rate of 50 ms.

・ The research group successfully detected the structural changes in single microcrystal grains caused by annealing at the picometer scale (one-tenth of the size of an atom).

・ The applicability of diffracted X-ray blinking (DXB) to inorganic materials was demonstrated, which will lead to the widespread application of DXB to improve the efficiency and durability of inorganic materials.

Abstract

The structures of polycrystalline materials have been determined by examining the mean properties of assemblies of millions of grains using X-ray diffraction measurement. However, it has been impossible to directly observe the local environment and interface structure of materials associated with the expression of functions and the "motion" of microcrystal grains that are related to structural features.

A research group consisting of scientists from the Graduate School of Frontier Sciences, the University of Tokyo, AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (AIST-UTokyo OIL), and Japan Synchrotron Radiation Research Institute (JASRI) successfully measured the dynamic changes (dynamics) in the ultrafine structure of single-crystal grains of silver halide, which rapidly change during X-ray photoreactions, and of the formed metallic silver. The measurement was performed using diffracted X-ray blinking (DXB) at the BL39XU beamline of SPring-8, a large synchrotron radiation facility. It was found from the time-resolved X-ray diffraction images of silver halide and metallic silver that the X-ray diffraction spots show tilting and rotational motion, revealing the changes in the lattice structure of individual crystal grains. To evaluate the grain motion, the time trajectory of the diffraction intensity reflecting these physical properties was analyzed by a single-pixel autocorrelation function (sp-ACF) developed by the research group. As a result, significant differences in the motion of crystal grains were observed between non-annealed and annealed silver halide and metallic silver. The research group realized a new measurement technique to define the local structural dynamics of polycrystalline materials. The achievements of this study were published online in Scientific Reports (Nature Publishing Group) on 5 March 2021.

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