Phase diagram of the ferroelectric relaxor(1−x)PbMg1/3Nb2

Abstract

Synchrotron x-ray powder diffraction measurements have been performed on unpoled ceramic samples of (1Ϫx)Pb(Mg 1/3 Nb 2/3)O 3 ϪxPbTiO 3 ͑PMN-xPT͒ with 30%рxр39% as a function of temperature around the morphotropic phase boundary, which is the line separating the rhombohedral and tetragonal phases in the phase diagram. The experiments have revealed very interesting features previously unknown in this or related systems. The sharp and well-defined diffraction profiles observed at high and intermediate temperatures in the cubic and tetragonal phases, respectively, are in contrast to the broad features encountered at low temperatures. These peculiar characteristics, which are associated with the monoclinic phase of M C-type previously reported by Kiat et al. ͓Phys. Rev. B 65, 064106 ͑2000͔͒ and Singh and Pandey ͓J. Phys. Condens Matter 13, L931 ͑2001͔͒, can only be interpreted as multiple coexisting structures with M C as the major component. An analysis of the diffraction profiles has allowed us to properly characterize the PMN-xPT phase diagram and to determine the stability region of the monoclinic phase, which extends from xϭ31% to xϭ37% at 20 K. The complex lansdcape of observed phases points to an energy balance between the different PMN-xPT phases which is intrinsically much more delicate than that of related systems such as PbZr 1Ϫx Ti x O 3 or (1Ϫx)Pb(Zn 1/3 Nb 1/3)O 3 ϪxPbTiO 3. These observations are in good accord with an optical study of xϭ33% by Xu et al. ͓Phys. Rev. B 64, 020102 ͑2001͔͒, who observed monoclinic domains with several different polar directions coexisting with rhombohedral domains, in the same single crystal.

Dynamic origin of the morphotropic phase boundary: Soft modes and phase instability in0.68Pb(Mg1/3Nb2/3Cao1, Stock2, Xu3 et al. 2008Phys. Rev. B262150View full textAdd to dashboardCite

“…7-11͒ and PMN-xPT. [11][12][13][14][15][16] It has since been argued that monoclinic symmetry may be an important property underlying the exceptional piezoelectric response of PMN-xPT and PZN-xPT as it allows the polarization vector to rotate freely within a plane 17 rather than be restricted to a particular crystallographic axis as is the case for the higher symmetry R, T, and orthorhombic ͑O͒ phases.…”

Role of the TiO6 octahedra on the ferroelectric and piezoelectric behaviour of the poled PbMg1/3Nb2/3O3–xPbTiO3 (PMN–PT) single crystal and textured ceramic

“…Different phase diagrams have been proposed [9][10][11] (see Figure 1). According to the common part of these zero-field phase diagrams the PMN-PT solid solutions with the PT content lower than 30% posses the typical relaxor behaviour characterized by the broad and strongly frequency dependent maximum of dielectric permittivity.…”

Piezoelectric enhancement of(PbTiO3)m/(BaTiO3)nferroelectric superlattices through domai

“…One well-known example is the generation of large piezoelectric responses in the vicinity of the morphotropic phase boundary (MPB) in ferroelectric solid solutions, i.e., Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) [2] and PbZrO 3 -PbTiO 3 (PZT) [3], through an easy polarization rotation via an intermediate monoclinic phase [4][5][6].…”