压力对铁电体Pb（Fe_（1／2）Nb_（1／2））O_3－Pb（Fe_（2／3）W_（1／3））O_3弥散相变的影响

HIGH PRESSURE EFFECTS ON THE DIFFUSED PHASE TRANSITION OF Pb (Fe_(1/2)Nb_(1/2))O_3-Pb(Fe_(2/3)W_(1/3)O￣3 CERAMIC

在０～１４ｋｂａｒ之间的不同流体静压力和－１９０～１００℃温度范围内测量了Ｐｂ（Ｆｅ１／２Ｎｂ１／２）Ｏ３－Ｐｂ（Ｆｅ２／３Ｗ１／３）Ｏ３铁电体复合材料的介电常数ε随温度、压力的变化特性．实验结果表明：温度和压力导致的相变都是弥散的；随压力的增加；介电常数峰值温度（或称宏观居里温度）Ｔｍ线性下降，其斜率ｄＴｍ／ｄＰ＝－３．１℃／ｋｂａｒ，介电常数峰值εｍａｘ降低，ε～Ｔ曲线弥散程度增大．用组分涨落模型对所得结果作了计算，并就压力对弥散相变的影响进行了唯象分析．

The dielectric constant s of Pb(Fe1/2Nb1/2)O3-Ph(Fe1/1W1/3)O3 binarysystem has been measured at high hydrosatic pressures from 0 to 14kbar andtemperature from -190℃ to 100℃. The experimental results indicate that temperature and Pressure-induced phase transitions are diffused. With increasingpressure) the phase transition temperature T. drops linearly with dTm/dP=-3.1℃/kbar, maximum permittivity εmax decreases, and the diffusion degree ofthe phase transition increases. These properties of diffused phase transition athigh pressure are discussed phenomenologically in this paper.