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采用Raman散射方法系统研究了Pb_(1-x)La_xTiO_3(PLT)的软模行为和铁电相变。结果表明,随着晶粒尺寸的减小,Pb_0.86La_0.14TiO_3(PLT14)能从常温常压下的四方铁电相转化为立方顺电相;在高温常压及常温高压下纳米晶PLT14的相变温度和压力均比体材料情况下低;对于不同晶粒尺寸的PLT体系,系统从四方相转化为立方相的相边界随晶粒尺寸的减小移向更低的La离子浓度,还论述了软模随晶粒尺寸、温度、压力和La离子浓度的变化行为以及系统发生相变的机制。
The soft-mode behavior and the ferroelectric phase transition of Pb_ (1-x) La_xTiO_3 (PLT) were systematically investigated by Raman scattering method. The results show that with the decrease of grain size, Pb_0.86La_0.14TiO_3 (PLT14) can transform from tetragonal ferroelectric phase to cubic paraelectric phase under normal temperature and pressure. Under the condition of high temperature and pressure, For the PLT system with different grain sizes, the phase boundary of the system transformed from the tetragonal phase to the cubic phase shifts to a lower La ion concentration as the grain size decreases, as also discussed The mechanism of the soft mold’s changing behavior with the grain size, temperature, pressure and La ion concentration and the phase transition of the system.