Characterization of the hydrothermally synthesized BaTiO₃

Abstract

From the scientific point of view, the properties of the fine powder provide us with the important information in the field of the material science. The dielectric property of the fine powder of ferroelectric material is one of the most interest subjects to know because it closely relates to corporation and domain phenomena. But, the dielectric property of the fine powder of ferroelectric material under the stress-free condition has not been measured, owing to the difficulty of estimation and compensation of the effect of medium. In this work, the dielectric property of the fine BaTiO₃ powder synthesized by hydrothermal rout was measured with use the new predicting equation of apparent dielectric constant of randomly mixed compound of fine particle as well as other several characterizing parameters.

The abnormal change or discontinuity of DTA, lattice parameter and dielectric constant was observed with 0.2 μm or larger powders at Curie temperature. Sharper abnormalities were observed with larger particle. As already reported by several researchers, the critical particle size at which the ferroelectricity appears was supposed to be less than or close to 0.1 μm.

Small abnormal frequency dependency was observed at about 3 GHz. It is not clear whether this abnormal frequency dependency comes from the domain wall motion, which was predicted by C. Kittel and observed by Yuri Popravko, or not.

Key Words:

• BaTiO₃
• dielectric property
• domain phenomena