Pb_(1-x)La_xTi_(1-x/4)O_3纳米晶相变的拉曼光谱研究

Studies of FT-Raman spectroscopy on the phase transition of Pb_(1 -x) La_xTi_(1 -x/4)O_3 nancrystals

用拉曼光谱在１５℃～３００℃观测了几种不同成分、不同粒径Ｐｂ１－ｘＬａｘＴｉ１－ｘ／４Ｏ３纳米粒子的铁电－顺电相变情况，讨论了掺杂效应和尺寸效应对居里温度的影响。结果表明 Ｅ（１ ＴＯ）软模解冻时能够观测到的最低频率均在 ５０ｃｍ－１以上，呈现出典型的弱阻尼特征，掺杂效应导致的空位和微 区成分的涨落使相变温度弥散。

The ferroelectric-paraelectric phase tracsition with defferent componet and variouw grain size of Pb1-xLaxTi1-x/4O3 nanocrystals was measured by using FT-Raman scattering at temperature range from room temperature to Curie Temperature(Tc). The influences of size effect and dopped effect on Tc were discussed. The result indicated that the soft mode E(1TO) soft mode for all samples was limited above 50cm -1 which showed typical underdamping characteristic. Doped effect lead to ion vavancy and change of microcompoisition, which make To diffused in a wider temperature scope.