Ruyan Guo

Origin of the High Piezoelectric Response in PbZr1-xTixO3

High resolution x-ray powder diffraction measurements on poled PbZr1-xTixO3 (PZT) ceramic samples close to the rhombohedral-tetragonal phase boundary (the so-called morphotropic phase boundary) have shown that for both rhombohedral and tetragonal compositions the piezoelectric elongation of the unit cell does not occur along the polar directions but along those directions associated with the monoclinic distortion. This work provides the first direct evidence for the origin of the very high piezoelectricity in PZT.

Tetragonal-to-monoclinic phase transition in a ferroelectric perovskite: The structure of PbZr0.52Ti0.48O3

The perovskitelike ferroelectric system PbZr1-xTixO3 (PZT) has a nearly vertical morphotropic phase boundary (MPB) around x=0.45–0.50. Recent synchrotron x-ray powder diffraction measurements have revealed a monoclinic phase between the previously established tetragonal and rhombohedral regions. In the present work we describe a Rietveld analysis of the detailed structure of the tetragonal and monoclinic PZT phases on a sample with x=0.48 for which the lattice parameters are, respectively, at=4.044 A, ct=4.138 A, at 325 K, and am=5.721 A, bm=5.708 A, cm=4.138 A, β=90.496°, at 20 K. In the tetragonal phase the shifts of the atoms along the polar [001] direction are similar to those in PbTiO3 but the refinement indicates that there are, in addition, local disordered shifts of the Pb atoms of ~0.2 A perpendicular to the polar axis. The monoclinic structure can be viewed as a condensation along one of the directions of the local displacements present in the tetragonal phase. It equally well corresponds to a freezing-out of the local displacements along one of the directions recently reported for rhombohedral PZT. The monoclinic structure therefore provides a microscopic picture of the MPB region in which one of the ‘‘locally’’ monoclinic phases in the ‘‘average’’ rhombohedral or tetragonal structures freezes out, and thus represents a bridge between these two phases.

The perovskite structure—a review of its role in ceramic science and technology

Abstract Starting with the history of the fundamental science of the relation of structure to composition delineated completely by Goldschmidt, we use the perovskite structure to illustrate the enormous power of crystal chemistry-based intelligent synthesis in creating new materials.The perovskite structure is shown to be the single most versatile ceramic host. By appropriate changes in composition one can modify the most significant electroceramic dielectric (BaTiO3 and its relatives) phase in industry, into metallic conductors, superconductors or the highest pressure phases in the earth. After an historical introduction of the science, detailed treatment of the applications is confined to the most recent research on novel uses in piezoelectric, ferroelectric and related applications.

Stability of the monoclinic phase in the ferroelectric perovskite PbZr1-xTixO3

Recent structural studies of ferroelectric

Piezoelectric and strain properties of Ba(Ti1−xZrx)O3 ceramics

{\mathrm{PbZr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{\mathrm{O}}_{3}

Micro-Raman scattering and dielectric investigations of phase transition behavior in the BaTiO3–BaZrO3 system

(PZT) with

Enhanced ferroelectric properties of Cr-doped BiFeO3 thin films grown by chemical solution deposition

x=0.48,

Dielectric behavior of Ba(Ti1−xZrx)O3 single crystals

have revealed a monoclinic phase in the vicinity of the morphotropic phase boundary (MPB), previously regarded as the boundary separating the rhombohedral and tetragonal regions of the PZT phase diagram. In the present paper, the stability region of all three phases has been established from high-resolution synchrotron x-ray powder-diffraction measurements on a series of highly homogeneous samples with

Ferroelectric-relaxor behavior of Ba(Ti0.7Zr0.3)O3 ceramics

0.42l~xl~0.52.

Raman spectroscopy of Mg-Ta order-disorder in BaMg1/3Ta2/3O3

At 20 K, the monoclinic phase is stable in the range