Fe-Ni-BaTiO3复合材料的介电行为及其机理研究

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，同时材料的介电关键词：3')" href="#">Fe-Ni-BaTiO₃渗流理论介电性能Maxwell-Wagner效应

Dielectric properties of a three-phase Fe-Ni-BaTiO3 composite

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 insulator-conductor transition with increasing metal concentration and the dielectric constant diverged near the percolation threshold. The dielectric constant reaches as high as 22000 when f_Metal=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.