Electric field effect on short-range polar order in a relaxor ferroelectric system

Abstract

Short-range polar orders in the relaxor ferroelectric material PbMg 1/3 Nb 2/3 O3-28%PbTiO3 (PMN-28PT) have been studied using neutron diffuse scattering. An external electric field along [110] direction can affect the diffuse scattering in the low temperature rhombohedral/monoclinic phase. Diffuse scattering intensities associated with [110] short-range polarizations are partially suppressed, while those arising from [110] polarizations are enhanced. On the other hand, short-range polar orders along other equivalent 110 directions, i.e. [101],[101], [011], and [011] directions, are virtually unaffected by the field.Our results, combined with previous work, strongly suggest that most part of short-range polar orders in PMN-xPT relaxor systems are robust in the low temperature phase, where they couple strongly to ferroelectric polarizations of the surrounding ferroelectric domains, and would only respond to an external field indirectly through ferroelectric domain rotation. PACS numbers: 63.20.kk,75.30.Ds,75.85.+t,61.05.fg PbMg 1/3 Nb 2/3 O 3 (PMN) is a prototypical lead based relaxor system where no long-range polar order can be established without an external electric field 1-4 . Due to the existence of strong random field 5-9 , short-range polar orders (SRPO), or, sometimes referred to as "polar nano-regions" (PNR) start to appear in the system at the Burn's temperture T d ∼ 620 K and grow with cooling 10 . These SRPO are believed to contribute to many unique properties of the relaxor material 11 . When mixed with the classical ferroelectric PbTiO 3 (PT), spontaneous ferroelectric polarizations can start to develop, and the solid solutions of PMN-xPT naturally exhibit combined ferroelectric and relaxor characteristics. In the mean time, the system shows extraordinary piezoelectric properties when approaching the Morphotropic Phase Boundary (MPB). There is evidence that the SRPO are important for the high piezoelectric responses as well [12][13][14] . The relaxor properties gradually disappear when the system crosses MPB into the regime of classic ferroelecrtrics [15][16][17][18] . For those with low PT concentrations, i.e. on the left side of the MPB, the SRPO can actually persist into the low temperature longrange ferroelectric ordered phase 19,20 , and therefore offers a fascinating platform to study how long-and short-range polar orders coexist and compete 21 .Diffuse scattering measurements are very sensitive to inhomogeneities in various materials systems, and have been used extensively to probe the SRPO in relaxors [22][23][24][25][26][27][28][29][30][31][32][33] . In general we find that in lead-based relaxors such as PMN-xPT and their analogue PZN-xPT, the diffuse scattering is dominated by intensities extending along 110 directions in reciprocal space (see Fig. 1), which is sometimes denoted as the "butter-fly diffuse" [due to its shape in the (HK0) scattering plane] or "T2 diffuse" (due to its relation to T2 phonon modes in the system) 34 . In order to determine how the SRPO affect ferroelec-FIG. ...

Achieving Excellent Energy Storage Properties in Fine‐Grain High‐Entropy Relaxor Ferroelectric Ceramics

“…These unique properties of relaxor ferroelectric ceramics are generally believed to originate from “polar nanoregions” (PNRs), which are caused by nanoscale cation disorder induced local phase fluctuation and strong random field. [ 14–17 ] Thus, relaxor ferroelectric ceramics can be considered as a system with short‐range polar order. At present, the relaxor behaviors of perovskite (ABO 3 ) ferroelectric ceramics are usually produced via cation doping on A‐ or/and B‐sites since the increase of cation disorder on a microscopic scale is conducive to the production of PNRs.…”

“…At present, the relaxor behaviors of perovskite (ABO 3 ) ferroelectric ceramics are usually produced via cation doping on A-or/and B-sites since the increase of cation disorder on a microscopic scale is conducive to the production of PNRs. [17,18] Therefore, one can imagine that if many kinds of cations are doped simultaneously with appropriate concentration, the system shall become a high-entropy ceramic.…”

Origin of polar nanoregions from displacive correlation in relaxor ferroelectric Pb(Mg1/3Nb2/3)O3–PbTiO3

“…This is a complement to the previously reported models, which mostly focused on the atomic structure of the PNRs. 48,49 The disordered matrix is to some extent similar to the local structure of classical ferroelectrics, in which the correlation between a dipole and its nearest neighbours is very weak 45 and the high-symmetry crystal structure is an average of the local displacements (dipoles) oriented away from the symmetry axes. The displacive correlations and their effects on the local to average structural transformation found in this work depict the origin of PNRs and their polar texture and orientations in relaxor ferroelectrics.…”

X-ray diffuse scattering and polar nanoregion of a relaxor ferroelectric under electric field

“…[19][20][21][22][23][24] Diffuse scattering intensities measured under an electric field exhibit a temperature dependence different from that under zero-field. [25][26][27][28][29][30][31] However, the electric field effects on diffuse scattering have not been fully explained by existing models. We present in this study a detailed electric field dependence of XDS intensities of PMN-30PT at 300 K and propose a plausible PNR model to explain the electric field effects.…”