We have developed the theory of boundary shielding approximation of electric polarization , from which the values of spontaneous polarization of some typical ferroelectric materials can be derived . the shielded charges in ferroelectricity are in the state of surface bound polaron - dipole whose creation and annihilation must span a potential barrier . by introducing statistical method , four types of typical electric hysteresis loops of some common crystals and ceramics have been given , which are well consistent with the experimental results 利用电极化的边界屏蔽近似,可计算出一些典型铁电单晶的自发极化强度.铁电屏蔽电荷处于表面束缚极化子偶状态,其产生和湮没要跨越位垒.由统计方法给出的一些常见晶体和陶瓷的四种典型电滞回线形状,和实验观察到的结果一致
If the position of the non - polarization slab shifts from the center to the surface , the number of the peaks of the susceptibility will change , and a step - like polarization curve is found . finally , two types of the dipolar defects are introduced into the lattice - based ferroelectric system 杂质层的空间位置的变化,如由中心对称位置向表面方向移动,会导致多层膜的相变温度升高,介电极化率由一个峰变为两个峰,多层膜的极化随温度升高出现跳跃下降( step一likepolarization ) 。
In this paper , we first investigate the impurity effect ( ba2 + ) on the dielectric and phase transition properties in srtio3 within the framework of the transverse - field ising model ( tim ) . then a possible coupling mechanism between the magnetism and dielectric properties in eutio3 is discussed and the magnetic influence on the frequency of the soft - phonon mode is investigated via the heisenberg model , soft - mode theory under the mean field approximation , the second quantization theory and the perturbation theory . and we proceed further investigation on eu1 - xbaxtio3 of 我们发现baxeul _ xtio3 ( o ‘ x ‘ 0 . 2 )的介电常数和由内察的偏置场导致的电极化除了随杂质浓度产生相应的变化,同时在磁和介电性质的藕合作用影响下在低温下偏离通常的量子顺电体行为,在尼尔温度附近出现异常,且磁场通过对最近邻自旋关联的作用来影响介电常数和电极化。