烧结温度对Bi_(0.7)Ba_(0.3)FeO_3陶瓷介电、铁电特性影响

用固相反应法在不同烧结温度下制备了Bi0.7Ba0.3FeO3陶瓷样品,研究了烧结温度对Bi0.7Ba0.3FeO3陶瓷结构、介电和铁电特性的影响.运用XRD进行物相分析可知,Bi0.7Ba0.3FeO3陶瓷样品为正交结构,主衍射峰与纯相BiFeO3一致,烧结温度在870℃以上时样品有良好的结晶度,电阻率达到108Ω?数量级.在一定的温度区间内,介电常数随烧结温度的升高而增大.在低频区830℃烧结的样品的介电损耗比较大,而对应于870℃和900℃两个烧结温度的样品介电损耗有了明显的减小;在高频区介电损耗对烧结温度的依赖性不大.样品的交流电导率随烧结温度的升高而增大.在900℃烧结的Bi0.7Ba0.3FeO3样品的Pr值可达到113.11μc/cm2,远大于纯相BiFeO3.通过Ba2+的A位掺杂进一步提高了纯相BiFeO3的介电、铁电性能.

Influence of the Sintering Temperature on the Dielectric and Ferroelectric Properties of Bi0.7Ba0.3FeO3 Ceramics

Bi_(0.7)Ba_(0.3)FeO_3 ceramic samples are prepared with various sintering temperatures using conventional solid state reaction method.X-ray diffraction is carried out to characterize the crystal structure of the samples.The results indicate that the samples have an orthorhombic structure but the main diffraction peak is consistent with the pure BiFeO_3 ceramics.The crystallinity of these samples increases with sintering temperature.The dc resistivity of Bi_(0.7)Ba_(0.3)FeO_3 ceramic prepared at 870 ℃ and above can reach ～108 Ω cm.The dielectric constant increases and the dielectric loss decreases as the sintering temperature increases.For all the three Bi_(0.7)Ba_(0.3)FeO_3 samples the ac conductivity increases with increasing sintering temperature and measurement frequency.A saturated P-E hysteresis loop is obtained with a Bi_(0.7)Ba_(0.3)FeO_3 sample prepared at 900 ℃,with a large remanent polarization (Pr) of 113.9 μC/cm~2 at an applied electric field of 20 kV/cm,indicating Ba doping enhances the ferroelectricity of BFO system.