The University of Tokyo School of Engineering Institute of Engineering Innovation

  Grain boundaries and interfaces in crystals have specific atomic structures due to the lattice disorder, which are the origin of various properties not generated in bulk. Local atomic structures in the GBs/interfaces are closely related to the mechanical and functional properties of materials. Furthermore, dopants and impurities are distributed around the GBs/interfaces and play important roles in determining macroscopic properties. To design new materials, it is necessary to understand the mechanisms of property-generation by precise analysis of the atomic structures and dopant distribution. With recent advances in materials synthesis processes, the microstructure of materials can now be controlled at the atomic level. Therefore, techniques to characterize the microstructure at higher resolution are demanded. Transmission electron microscopy (TEM) is one of the most useful techniques to observe the internal structures. TEM makes it possible to perform atomic structure analysis and local composition/state analysis at the nanometer scale. The nanoscale analysis has developed dramatically in recent years. For example, scanning transmission electron microscopy (STEM) with spherical aberration correction gives column-by-column information about the elements, their position and their electronic state. Our research focuses on investigating and predicting the mechanisms for generating material properties by combining experimental techniques, such as leading-edge high-resolution TEM, STEM, energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS), and theoretical calculations.