Preparation of nm-sized BaTiO_3 Crystallites by The 2-step Thermal Decomposition of Barium Titanyl Oxalate and Their Dielectric Properties

摘要

In this study, we proposed to prepare the fine BaTiO_3 particles by a new 2 step decomposition of barium titanyl oxalate (BaTiO(C_2O_4)_2·4H_2O). The 1st step is the thermal treatment of BaTiO(C_2O_4)_2·4H_2O at 400℃ for 1 hour under O_2 flow for the purpose of the removal of carbon species. The 2nd step is the formation of the fine BaTiO_3 particles by the thermal treatment at various temperatures in vacuum. As a typical case, the fine BaTiO_3 particles with a size of about 16.5 nm were obtained by the treatment at 600℃ for 0.5 hour in vacuum. The dielectric properties of these particles were measured below 30MHz using the impedance analyzer. This method was composed of two parts; (1) the dielectric measurement using the slurry of the BaTiO_3 crystallites with 1-propanol and (2) the simulation using the electrostatic field analysis of the finite element method. When these two kinds of the values become to same, the dielectric constant of the BaTiO_3 crystallites can be determined. Using this powder dielectric measurement, the dielectric constant of the BaTiO_3 crystallites with a size of 16.5 nm was determined at almost 400.