THz region dielectric properties of barium titanate fine particles using infrared reflection method

The THz region dielectric properties of barium titanate (BaTiO₃) fine particles were measured using the infrared (IR) reflection method. Prior to this measurement, to minimize the scattering light caused by surface roughness, the preparation of the dense 3D colloidal sphere arrays (colloidal crystals) with a flat surface was tried. First, the BaTiO₃ fine particles were well dispersed into diethylene glycol as an organic solvent, and this BaTiO₃ slurry was dried very slowly at 80 °C. Finally, the dense BaTiO₃ colloidal crystals were successfully prepared. The IR reflection method was performed using these dense BaTiO₃ colloidal crystals, and their IR reflection spectra were measured from 100 to 1200 cm^-1. As a result, by the use of the dense BaTiO₃ colloidal crystals, the high intensity reflection spectra of the BaTiO₃ fine particles were successfully obtained. The spectra were analyzed using a four-parameter semi-quantum (FPSQ) model, and finally, the THz region dielectric properties were estimated for the BaTiO₃ fine particles.