STRUCTURAL INSTABILITIES IN PZT

The local atomic structure of Pb(ZrxTi1-x)O-3(PZT) (x = 0, 0.1) was ex amined using the atomic pair distribution functiuon (PDF) analysis of the pulsed neutron powder-diffraction data. It was found that the loca l atomic structure deviates significantly from the crystallographic lo ng range structure, and varies less with the composition than the crys tallographic average structure does. The crystallographic structure of PbZrO3 (PZ) is orthorhombic and is characterized by the [110] relatio n of ZrO6 octahedra, while locally the octahedra are also rotated arou nd the {111} axis, with the z-component of the axis randomly chosen. T he structure of PZT (x > 0.05) is rhombohedral and is dominated by the [111] rotation, while locally the axis of rotation is closer to [110] . The Pb displacements reflect these strong deviations, and locally ha ve large z-components even in PZ.