CaCu_3Ti_4O_(12)陶瓷松弛损耗机理研究

Investigation on relaxation loss mechanism of CaCu_3Ti_4O _(12) ceramic

CaCu3Ti4O12介电损耗较大且损耗机理尚不明确,因此限制了其应用.本文采用固相法和共沉淀法合成CaCu3Ti4O12陶瓷,利用宽带介电温谱研究在交流小信号作用下,双Schottky势垒耗尽层边缘深陷阱的电子松弛过程、载流子松弛过程以及CaCu3Ti4O12陶瓷的介电损耗性能.研究发现,在低频下以跳跃电导和直流电导的响应为主,而高频下主要为深陷阱能级的松弛过程所致,特别是活化能为0.12eV的深陷阱浓度,这是决定CaCu3Ti4O12陶瓷高频区介电损耗的重要因素.降低直流电导,有利于降低低频区介电损耗;而高频区介电损耗的降低,需要降低深陷阱浓度或增大晶粒尺寸.共沉淀法制备的CaCu3Ti4O12陶瓷,有效降低直流电导及控制深陷阱浓度,介电损耗降低明显.

The dielectric loss of the CaCu3Ti4O12 ceramic is high, and the mechanism of the loss is not clear, Which restricts its application. The Cafu3Ti4O12 ceramic samples are synthesised by solid state reaction method and coprecipitation method. The electronic relaxation of deep bulk traps at the depletion layer edge, carrier relaxation and the dielectric loss of CaCu3Ti4O12 ceramic are investigated. Both perfect double Schottky barrier and low impurity density can reduce the DC conductivity, thus reducing the low-frequencydielectric loss. High-frequency dielectric loss is controlled by deep bulk trap density, especially in the one whose activation energy is 0.12 eV. At room temperature, when the frequency is 1 kHz, the dielectric constant and loss of CaCu3Ti4O12 ceramic prepared by coprecipitation method are 1.4 × 10^4 and 0.037, indicating a good improvement.