溶胶凝胶法制备掺铅钛酸钡纳米晶及其结构相变

采用溶胶－凝胶工艺制备了不同晶粒大小的、掺铅（５ｍｏｌ％）钛酸钡（ＢＰＴ）纳米晶．用ＴＥＭ、ＸＲＤ和ＤＳＣ研究了ＢＰＴ样品的晶粒大小、结构及其相变特性．结果表明，纳米晶ＢＰＴ随着晶粒尺寸的减小，由铁电四方相向顺电立方相过度，并且相变变得弥散．其顺电－铁电相变随着晶粒尺寸的减小而消失．另一方面，随着晶粒尺寸的增加，其铁电四方－铁电正交相交消失，即抑制了其正交相的形成．

Structure Phase Transition of Nanocrystalline Barium Titanate Doped with Lead Prepared by Sol-Gel Methods

Nanocrystalline (Ba,Pb)TiO3 (5 mol% Pb) with various grain sizes were prepared by a sol-gel process. The gain size, structure and phase properties of nanocrystalline BPT were studied by TEM, XRD and DSC. The results show that the structure phase transition is from ferroelectric tetragonal to paraelectric cubic phase and becomes more diffusive with decreasing particle size. On the other hand, the ferroelectric orthorhombic to ferroelectric tetragonal phase transition disappears with increasing particle size, it means that the formation of the unwanted orthorhombic phase of BaTiO3 is inhibited.