【摘要】 基于Kittel的反铁电体唯象理论,从正和反电场方向双吉布斯自由能的角度出发,导出了反铁电耦合条件下电场对偶极子转向和对正反极化强度的影响规律,最终得到了电场相关的反铁电体的电滞回线和介电常数.数值模拟的结论是:在一个电场周期内电滞回线呈现双回线;在半个电场周期内,介电常数呈现双峰.当改变反铁电耦合强度和温度时,得到的电滞回线与介电常数的变化规律与报道的实验结果相吻合.反铁电耦合强度的增强或温度的降低,都会使反铁电性增强,表现为反铁电相到铁电相的临界转变电场增大,并在一定条件下消失,即因极高的临界转变电场使反铁电回线转变为细长的铁电型电滞回线.深入分析表明,该回线实质上为强反铁电体的特性,而并非表面所呈现的铁电相.更多还原

【Abstract】 Based on the Kittel’s phenomenological theory on the antiferroelectrics, variation laws of positive polarization and negative polarization along electric field are deduced from double Gibbs free energy aspect under the condition of antiferroelectric coupling coefficient, and finally the antiferroelectric electric hysteresis loop and dielectric constant are deduced. The results of numerical simulation show that the hysteresis loop in a period of electric field is double loop, and the dielectric constant is bimodal during half period of electric field. When the strength of antiferroelectric coupling and temperature are changed, the variations of hysteresis loop and peaks of dielectric constant are consistent with the reported experimental results: with the decrease of temperature in the antiferroelectric phase and the increase of antiferroelectric coupling strength, the critical transition electric field from the antiferroelectric phase to the ferroelectric phase gradually increases, and even disappearing at certain conditions which results in a transformation of the antiferroelectric loop into a slender ferroelectric phase-like hysteresis loop. The phenomenon can be explained that the slender loop actually is another typical characteristic of strong anti-ferroelectricity, rather than the ferroelectricity presented from shape.更多还原