铌酸钡钠和钽酸锂铁电相变的实地观察

本文报道了用透射电子显微镜实地观察铌酸钡钠和钽酸锂铁电相变的实验结果。在室温电畴的尺寸为0.2—1μm。当温度增加到接近居里点时,形成准规则排列的微畴结构,其尺寸为几百埃,实验结果用稍微修正了的模型进行了解释。在钽酸锂中当接近铁电相变温度时,发现了强烈的辐照损伤,这可能跟相变的软模有关。 关键词：

IN SITU TEM STUDIES OF FERROELECTRIC PHASE TRANSITIONS IN Ba2NaNb5O15 AND LiTaO3

In this paper we presented our experimental results of in situ TEM observations of ferroelectric phase transitions in BaBa₂NaNb₅O₁₅ (T_c =550℃) and LiTaO₃ (TC = 660℃). At room temperature the domain patterns are of the scale 0.2-1 μm. Increasing the temperature to near T_c, the micro-domains forming quasi-regular arrays of the scale about several hundreds of angstroms have been observed and interpreted according to a model slightly modified from that of Селок. A strong susceptibility to radiation damage is found in LiTaO₃ near phase transition temperature which may be connected with soft modes of phase transitions.