| Summary: | 碩士 === 國立成功大學 === 資源工程學系碩博士班 === 97 === Barium titanate is a dielectric and ferroelectric material that used widely in electrical applications, including multilayer ceramics capacitors (MLCCs), PTCR thermistors, etc. Moreover, the microstructure, crystalline phase, Curie temperature and dielectric constant of barium titanate are affected easily by Ba/Ti ratio and particle size. In order to realize the effects of Ba/Ti ratio on BaTiO3 powder, high purity BaCO3 and TiO2 were used to synthesize non-stoichiometric BaTiO3 via solid state reaction, and tried different heating parameters to control the BaTiO3 powder with similar particle size in this study.
After analyzing the powder with similar particle size, the tetragonality decreases and the Curie temperature shifts to lower temperature when Ba/Ti ratio strays from 1. The dielectric constant of BaTiO3 powder is also measured in this study. The dielectric constant shows higher when Ba/Ti ratio is closed to stoichiometry.
The dielectric constant of bulk is measured. The dielectric constant of bulk with Ba/Ti ratio = 0.9837 is higher than each other just because that with grain size about 0.7 ~1 �慆, moreover, the distribution of grain size is quit homogeneous.
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