Fe-Ni-BaTiO_3复合材料的介电行为及其机理研究  

Dielectric properties of a three-phase Fe-Ni-BaTiO_3 composite

作　　者：黄集权[1] 洪兰秀[2] 韩高荣[1] 翁文剑[1] 杜丕一[1] 

机构地区：[1]浙江大学硅材料国家重点实验室,杭州310027 [2]浙江大学电气工程学院,杭州310027

出　　处：《物理学报》2006年第7期3664-3669,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50372057和50332030);国家重点基础研究专项基金(批准号:2002CB613302)资助的课题.~~

摘　　要：利用金属铁、镍(Fe与Ni保持mol比为22∶78不变)与钛酸钡复合,在保护气氛下成功烧结制备了高介电常数Fe-Ni-BaTiO3复合陶瓷材料,并研究了该复合材料的电导和介电性能及其物理机理.分析结果表明,由于渗流效应,随着陶瓷中金属含量的增加,材料经历了绝缘体—导体突变.同时,在渗流阈值附近,材料的介电常数有了极大的提高.当金属体积含量为0.23时,即在绝缘体向导体转变的渗流阈值附近,复合材料的介电常数达到了22000,为同条件下制备的纯钛酸钡陶瓷体介电常数的12倍,同时材料的介电损耗仍保持为较低值.材料具有明显的Maxwell-Wagner效应特征,这表明传导机理对材料的介电常数的提高起到了很重要的作用.分析了传导机理对介电的影响.Fe-Ni-BaTiO3 three-phase composites with super high dielectric constant were successfully prepared by sintering BaTiO3 with various amount of metal （Ni and Fe with a fixed mol ratio of 78：22） in nitrogen atmosphere at 1250%： for 2h. The impedance and the dielectric properties were measured by an Agilent 4294A precision impedance analyzer, and the dc conductivity was measured by a Keithley 6571 high resistance meter. The results indicate that this type of composite undergoes an insulatorconductor transition with increasing metal concentration and the dielectric constant diverged near the percolation threshold. The dielectric constant reaches as high as 22000 when fMetal = 0.23, which is about 12 times that of the BaTiO3 matrix, while the dielectric loss keeps still a low and stable value of about 0.08 with increasing metal concentration. And the dielectric relaxation shows a notable Maxwell-Wagner characterization, which suggests that conduction mechanisms may play an important role in the dielectric response.

关 键 词：Fe-Ni-BaTiO3 渗流理论 介电性能 Maxwell-Wagner效应 

分 类 号：TB331[一般工业技术—材料科学与工程]