Li_(0.12)Na_(0.88)NbO_3晶体的铁电—铁电相变

Ferro-Ferroelectric Phase Transition in Li_(0.12)Na_(0.88)NbO_3 Crystals

测量了 Li_(0.12)Na_(?)NbO_3晶体在300K 至10K 温度范围内的介电常数、热释电系数和电阻特性。在低温范围,介电常数和电阻发生突然变化,热释电系数出现峰值,它们表示晶体中发生了铁电—铁电相变,而且该相变有约80K 的热滞。根据低温时自发极化的取向以及室温相的点群(4 mm),借助居里原理,得知低温相的点群为 m。

The dielectric constant,pyroelectric coefficient and resistance of Li_(0.12)Na_(0.88)NbO_3crystals were measured in the temperature range of 300 K to 10 K.An abrupt chan-ge in the dielectric constant and resistance,and a peak in the pyroelectric coefficientwhich are indicative of a ferro-ferroelectric phase transition were observed.Accord-ing to the orientation of low temperature spontaneous polarization and room tempera-ture point group(4 mm),with the aid of Curie principle,the point group of the lowtemperature phase was determined to be m.