CaCu_3Ti_4O_(12)陶瓷的介电性能及其内耗

Study on Dielectric Properties and Internal Friction of CaCu_3Ti_4O_(12) Ceramics

采用固相反应法制备CaCu3Ti4O12陶瓷材料,用阻抗分析仪测定其介电常数和内耗.结果表明:在频率一定的条件下,CaCu3Ti4O12陶瓷的内耗在某一温度时出现了一个最大值,偏离该温度时内耗迅速下降;随着频率增加,内耗峰向高温区域移动.在低温条件下,CaCu3Ti4O12陶瓷的介电常数较小;当达到某一温度后,介电常数发生突变;当大于该温度后,介电常数基本维持在较高值,且随频率增加,所对应的温度逐渐升高.CaCu3Ti4O12陶瓷的介电常数与其内禀结构、阻挡层电容有关,内耗和频率与温度的关系满足极化子模型;而在一定温度下介电常数发生的突变亦与极化子本身的特性有关.

CaCu3Ti4O12 ceramics were fabricated by solid-state reaction method.The dielectric properties and internal friction were measured by impedance meter.The results show that the internal friction of CaCu3Ti4O12 ceramics reaches its maximum at a certain temperature under a given frequency,and decreases rapidly when being offset from the temperature.On the other hand,there is a shift of internal friction to the high temperature region with the frequency increasing.A further study shows that the dielectric constant of the ceramics is smaller at a low temperature,but it suddenly changes at a certain temperature,then keeps the higher value with the increase of temperature.Meanwhile,the corresponding temperature for the sudden change increases with the frequency.The giant dielectric constant of CaCu3Ti4O12 has some relation with the intrinsic structure and barrier-layer capacitance,and the mutual dependence relations between the internal friction,frequency and the temperature are adapted to the polarization model,in which the sudden change induced by the dielectric constant under a certain temperature is related to the characteristic of the polaron.