钛酸铅晶体反铁电相至电场感应铁电相相变的研究

Phase Transition of PbTiO3 Antiferroelectric Phase to Electric-Field-Induced Ferroelectric Phase

仔细研究了PbTiO3电场感应铁电相的晶体结构。在初始反铁电相中，各离子位移方向与极轴垂直，但在外电场感应下，Pb离子沿极轴方向有相同方向0．17h的位移，从而使晶体呈现铁电相特征，发生反铁电一铁电相变。此铁电相称之为电场感应铁（EFI）电相。通过结构对称性分析，确定EFI铁电相的对称性是C2mm（G2v），用极矢量Ps作为序参量来描述相变时对称性的变化是合适的。

The structure of electric-field-induced PbTiO3 ferroelectric phase has been studied in detail The polar axis is found to be orthogonal to the direction of atomic displacements in the initial antiferroelctric phase. The ferroeletric properties of the phase are due to a Pb displacement of about 0. 17A relative to the oxygen framework along the polar axis in the effect of applying the electric field, and there is a phase transition of PbTiO3 from Antiferroeletrice to ferroelectric which is called electric-field-induced ferroelectric phase （EFI）. By the analysis of structural symmetry, the symmetry group of EFI PbTiO3 ferrroelectric Phase is ascertained to be C2v. The polar vector Ps was chosen to be the order parameter of this phase transition.