(a) Electron Crystallography (Electron-diffraction and -microscopy)

Crystal symmetries, microscopic crystal structures, atom positions, Debye-Waller factors and bonding charge distribution are studied by convergent-beam electron diffraction (CBED) and electron microscopy using an energy-filter transmission electron microscope. These techniques are applied to phase transformations of ferroelectric substances, higher-dimensional structures of quasicrystals and incommensurate crystals, charge/orbital-ordering phenomena of strongly-correlated electron systems and lattice defects and interface structures of semiconductors.

(b) Electron Spectroscopy (EELS and SXES based on electron microscopy)

Electronic structures of solids in nm-scale specimen area are studied by a high energy-resolution electron energy-loss spectroscopy (EELS) microscope and a newly developed soft-X-ray emission spectroscopy (SXES) microscope. These studies include a systematic investigation of carbon allotropes (C₆₀,C₇₀,....., carbon and boron-nitride nanotubes), boron allotropes (pure and metal-doped α, β-boron and related boron compounds), band structures of oxide superconductors (Bi-, La-systems), the metal-insulator transitions of transition metal oxides, pseudo-gap structures of quasicrystals, the defect levels of semiconductors and multi-layer materials and plasmons in metals and alloys.

Electrostatic potential of orbital ordered phase of FeCr2O4 determined by CBED and orbital ordered model.

High-resolution tranmission electron microscope (TEM) image of boron nanobelt and crystal structure model.