Fe掺杂CaCu3Ti4O12陶瓷的介电性能与弛豫特性研究

采用固相反应法制备了CaCu₃Ti_4-xFe_xO₁₂(0≤x≤0.2)陶瓷，通过X射线衍射、扫描电子显微镜、介电频谱和阻抗谱等手段研究了Fe对CaCu₃Ti₄O₁₂陶瓷的结构和介电性能的影响.研究发现：CaCu₃Ti_4-xFe_{x关键词： 巨介电常数 双阻挡层电容模型 界面极化}

Study on the dielectric properties and dielectric relaxation of Fe-doped CaCu3Ti4O12 ceramics

The CaCu₃Ti_4-xFe_xO₁₂ (0≤x≤0.2) ceramics have been prepared by a standard solid-state reaction method, and the influence of Fe doping on the microstructure and dielectric properties of CaCu₃Ti_4-xFe_xO₁₂ ceramics were investigated by the X-ray diffraction, scanning electron microscopy, dielectric spectroscopy and impedance spectroscopy. It has been found that complete solid solutions are formed for all of the compositions x. With the increase of Fe content, the semiconductivity of grain vanishes gradually and the dielectric constant decreases. For specimens with x≤0.04, the two dielectric relaxation process Ⅰ and Ⅱappeared in the frequency ranges of 10⁶—10⁸ and 10³—10⁴ Hz, respectively. These two dielectric relaxation process were considered to be associated with grain boundaries and interfacial polarization between the electrode and ceramic surface, respectively. In addition, the third dielectric relaxation Ⅲ was detected in the high-temperature dielectric spectroscopy of CaCu₃Ti_3.99Fe_0.01O₁₂ ceramic, which was caused by a hopping process of localized charge carriers. The activation energy of this thermally excited relaxation is 0.78 eV, as obtained by using the Arrhenius formula.