CaCu_3Ti_4O_(12)多晶块体的巨介电常数研究

Giant Dielectric Constant of Polycrystalline Bulk CaCu_3Ti_4O_(12)

采用固相法制备了Ca Cu3Ti4O12多晶块体,研究了其介电常数随温度和频率的变化。结果表明,在温度为300 K、频率为1 k Hz时,多晶块的介电常数高达14 000;频率为1 k Hz时,介电常数基本不随温度的变化而改变。动态变化的极化弛豫使Ca Cu3Ti4O12多晶块具有巨介电常数,混合价Ti离子导致极化子的热激活使Ca Cu3Ti4O12多晶块的介电特性出现反常效应。

The polycrystalline bulk Ca Cu3Ti4O12 was prepared by solid-phase method, and the changes of dielectric constant with the temperature and frequency were investigated. The results show that the dielectric constant of polycrystalline bulk is up to 14 000 when the temperature is 300 K and the frequency is 1 k Hz. The dielectric constant is nearly unchanged with the temperature when the frequency is 1 k Hz. The polycrystalline bulk Ca Cu3Ti4O12 has a giant dielectric constant due to the dynamic changes of the polarization relaxation. At the same time, thermally activated polaron caused by mixed-valence Ti ions leaded to the unusual dielectric properties of polycrystalline bulk Ca Cu3Ti4O12