电荷有序Ln2-xSrxNiO4陶瓷的巨介电效应与小极化子跃迁

项目名称： 电荷有序Ln2-xSrxNiO4陶瓷的巨介电效应与小极化子跃迁

项目编号： No.51272233

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 一般工业技术

项目作者： 刘小强

作者单位： 浙江大学

项目金额： 79万元

中文摘要： 电荷有序Ln2-xSrxNiO4(x=0.5,0.25)陶瓷中观测到高频巨介电效应，这为巨介电常数材料在高频应用打开了大门，在分析电荷有序与巨介电效应关联的基础上，我们提出了小极化子跃迁模型。本项目拟在以上工作基础上，着眼于电荷有序Ln2-xSrxNiO4 (Ln=La, Nd, Sm) 陶瓷中的介电弛豫及巨介电效应，首先通过改变材料的组成并结合烧结后的热处理来调控小极化子的尺度与浓度，分析材料介电常数、介电响应频率以及激活能的变化规律，并与小极化子跃迁模型的预测结果进行比对来确认两者的关联；随后，利用材料的电输运特性给出小极化子的特性，从而给出该材料体系巨介电效应的物理本质与结构根源；最后在该模型基础上，利用形成核-壳结构新方法，来探索优化与调控Ln2-xSrxNiO4陶瓷巨介电效应的有效途径，为该材料的实用化奠定基础。

中文关键词： 巨介电效应；小极化子；氧空位；过量氧；绝缘阻挡层

英文摘要： The giant dielectric responses in the charge-ordered Ln2-xSrxNiO4 (x=0.5,0.25) ceramics up to high frequency were observed, and this might provide the possible application of giant dielectric materials at high frequency. After analysising the link between charge ordering and giant dielectric response, a small polarnic hopping model was proposed. Based on aboved results, we focuse on the giant dielectric response and dielectric relaxation in the charge-ordered Ln2-xSrxNiO4 (Ln=La, Nd, Sm) ceramics in the present project. First, the size and concentration of small polaron can be tuned by changing the component and the post heat-treating, after comparing the experimental dielectric constant, response frequency and activation energy of dielectric relaxation with the predicted results from the small polaronic hopping model, the correlation between the giant dielectric respone and small polaronic hopping can be confirmed. Then, with the help of character of small polaron from the electric transport measurement, the detailed structural origin of the giant dielectric response in the present materials are given. Final, based on the above model, a new effective method, formation of the core-shell structure, to optimize and control the giant dielectric response of Ln2-xSrxNiO4 ceramics is proposed, and the method may lead

英文关键词： Giant dielectric response；Small polarons；Oxygen vacancies；Excess oxygen；Insulated barrier layer