巨介电常数氧化物CaCu3Ti4O12的介电和阻抗特性

采用固相烧结法合成了单相巨介电常数氧化物CaCu₃Ti₄O₁₂（CCTO）.用阻抗分析仪分析了10—420 K温度范围内的介电频谱和阻抗谱特性，并结合ZVIEW软件进行了模拟.结果表明：温度高于室温时，频谱出现两个明显的弛豫台阶，低频弛豫介电常数随温度升高而显著增大，表现出热离子极化特点；温度低于室温时，频谱表现出类德拜弛豫，且高、低平台介电常数值基本不随温度变化，表现出界面极化特点和较好的温度稳定性.频谱中依次出现的介电弛豫对应于阻抗谱中 关键词： 3Ti₄O₁₂')" href="#">CaCu₃Ti₄O₁₂ 介电频谱 阻抗谱 Cole-Cole半圆弧

Dielectric and impedance performances of giant dielectric constant oxide CaCu3Ti4O12

Pure colossal dielectric constant oxide CaCu₃Ti₄O₁₂ (CCTO) compound was prepared by traditional ceramic processing. Dielectric dispersion and complex impedances spectra were investigated using a impedance analyzer within a temperature range of 10—420 K. The data were simulated by “ZVIEW” software. The result indicates that there are two obvious relaxations in the dielectric dispersion spectra when the temperature is higher than room temperature and the dielectric constant increases remarkably with increasing temperatures at a low frequency, which indicates a thermal ionic polarization. However, the frequency spectra becomes similar to Debye-type relaxation when the temperature is lower than room temperature and the low-and high-frequency relaxation step almost keeps unchanged with temperature, which reveals a feature of interface polarization and considerable temperature stability for CCTO. The relaxation revealed in the frequency spectra corresponds to the three different semicircles revealed by the impedance spectra, which indicated there are three inhomogeneous regions or polarization processes in CCTO ceramics and the colossal dielectric constant mainly comes from the extrinsic polarization of these inhomogenities. The activation energies are found to be respectively 0.05 eV, 0.58 eV and 0.49eV for the three different polarization processes by simulating the impedance semicircles using an equivalent circuit.