CaCu3Ti4O12巨介电常数陶瓷电子陷阱介电弛豫特性与机理的研究

项目名称： CaCu3Ti4O12巨介电常数陶瓷电子陷阱介电弛豫特性与机理的研究

项目编号： No.51277138

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 电工技术

项目作者： 成鹏飞

作者单位： 西安工程大学

项目金额： 60万元

中文摘要： CaCu3Ti4O12（CCTO）材料具有高达数万且几乎不随温度变化的巨介电常数，优异的介电性能使CCTO有望代替铁电体在多个领域形成广泛的应用。但是由于其极化机理及极化与电导的关联尚不清楚，介电损耗难以降低，严重制约了CCTO的实际应用。本项目以具有面缺陷的非均匀显微结构为基础，分析M-W极化机制的内在矛盾，提出电子陷阱弛豫新机制；通过原子力显微镜（AFM）对微区I-V特性的测量、热刺激电流（TSC）的分析、介电谱对介电弛豫与点缺陷之间内在关系的研究，明确电子陷阱弛豫对CCTO巨介电常数的根本性作用；根据电导机制的不同，通过导纳谱分离、鉴别直流电导、类Debye弛豫电导和局域电荷跳跃电导，建立极化与电导的关联；分析低频损耗和高频损耗的起源，通过点缺陷结构调控达到介电常数基本不变而介电损耗显著下降的目的。本项目的研究对于促进非均匀复杂结构材料极化机理研究及CCTO的实际应用具有重要意义。

中文关键词： CaCu3Ti4O12陶瓷；介电弛豫机制；电导机制；点缺陷；精细介电谱

英文摘要： CaCu3Ti4O12 (CCTO) material possesses a colossal dielectric constant as high as ten thousands and the dielectric constant is almost invariant with temperature. The excellent dielectric properties make the material as a competitor of ferroelectrics in many applied fields. However, a certain inherent correlation between high dielectric constant and high conductance gives rise to high dielectric loss, which restricts the practical application of CCTO. On the basis of inhomogeneous microstructure with planar defects, internal contradiction of Maxwell-Wagner polarization mechanism applied in CCTO is analyzed. After the verification of nonlinear I-V characteristics of planar defects, a new model of electronic trap relaxation mechanism is proposed and verified by thermally stimulated current (TSC). With the help of wide band dielectric spectroscopy, the intrinsic relationship between high frequency and low frequency dielectric relaxation and the relationship between dielectric relaxation and intrinsic point defects of CCTO is explored and the fundamental effect of electronic trap relaxation on the colossal dielectric constant is discussed. According to the difference of conductivity mechanism, direct current (DC) conductivity, dielectric relaxation conductivity and localized state charge hopping conductivity are separa

英文关键词： CaCu3Ti4O12 ceramics；dielectric relaxation mechanism；conduction mechanism；point defect；fine dielectric spectroscopy