(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)
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
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.