Abstract Scope |
Intrinsic dielectric properties of high-permittivity materials such as perovskite oxides are predominantly determined by the ionic polarizations related to the lattice vibrations (phonon). Therefore, it is necessary to measure the complex dielectric permittivity as a function of frequency in THz region to understand the origin of the intrinsic dielectric property. In this presentation, I will introduce THz dielectric spectra of typical dielectric and ferroelectric materials. Recently, we uniquely developed an ellipsometric system for determining THz dielectric functions of high-permittivity materials directly. We have been evaluating the complex permittivity of various materials using this system, and analyzing the vibration and diffusion of ions in solids with the aid of theoretical calculations. In addition to the polarization mechanism of typical perovskite-type oxides, I will introduce cation / anion substitution effects, size effect, design of novel materials, and so on. |