关键词: 钛酸钡, 镧, 陶瓷, 非均匀形核, 淀积, 包覆

Abstract:

Hvdrothermally-synthesized barium titanate powders were coated with La(OH)₃ through a heterogeneous nucleation processing technique with La(NO₃)₃ as the La source.The pH value during the heterogeneous nuclea-tion was calculated based on the theory of solubility product. By controlling the pH value in dispersed BaTiO₃ sus-pension, La₂O₃-coated BaTiO powders and ceramics with a homogeneous and stoicheometry composition of (Ba_1-3x/2M/La )TiO₃ were then prepared. Meanwhile,the influence of La content on the sintering behaV or,phaLse structure.resistivity and dielectric constant-temperature dependence of the La-doped BaTiO₃ ceramics added with SiO₂ was discussed. Expe:rimental results demonstrate that the La-doped BaTiO₃ ceramics with homogeneous and stoicheometry composition CaD．easily be prepared by the doping method mentioned above· It is also found that the Curie temperature of the prepared BaTiO3 ceramics decreases linearly with the increase of La₂ O₃ content,and that more La is needed to make a BaTiO semicondsucting ceramic derived from the method than by an oxide-mixing re-action method.

Key words: barium titanate, lanthanum, ceramic, heterogeneous nucleation, deposition, coating