Pressure-induced structural transformations in pure and Ru-doped 0.9PbZn1/3Nb2/3O

N. Waeselmann

¹

,

Bernd Maier

²

,

Boriana Mihailova

³

et al.

Abstract

Pressure-induced structural transformations in relaxor-based perovskite-type (ABO 3 ) 0.9PbZn 1/3 Nb 2/3 O 3 -0.1PbTiO 3 single crystals which have a very high piezoelectric response were studied by single-crystal x-ray diffraction and Raman spectroscopy at room temperature and pressures up to 18.1 GPa. Changes in state of long-range order were observed near 1.0 GPa, 2.1 GPa, and 5.9 GPa. Initially, upon pressure increase the ferroic deviation of the atomic positions from the cubic structure is reduced but the ferroelectric twinning is enhanced and near 1.0 GPa the intrinsic ferroelectric multiphase domain pattern formed in the as-synthesized crystals is changed. At 2.1 GPa the system undergoes a phase transition from a ferroelectric to a relaxor state, which exhibits an average cubic structure but still contains polar nanoregions. At 5.9 GPa a reversible phase transition typical of Pb-based perovskite-type relaxors occurs, namely a cubic-toantiferrodistortive phase transition resulting in a long-range order of antiphase octahedral tilts. On decompression the ferroelectric state reappears below 2.1 GPa and the local atomic structure is fully recovered at ambient pressure but the final domain texture differs from the initial one. Ruthenium doping on the B-site does not influence the pressureinduced structural transformations.

High pressure Raman spectroscopic studies of the relaxor ferroelectric 0.85Pb(Zn1/3Nb2/3)O3-0.15PbTiO3

“…14 Furthermore, the PNRs in the Pb-relaxor are understood to be pinned onto CORs and driven by its chemical ordering. 12,13,[25][26][27][28] On the other hand, in contrast to these findings, several reports indicating non-substantial role of CORs on PNRs dynamics also. [29][30][31] High pressure structural studies of solid solutions between relaxors and normal ferroelectrics are rare.…”

“…This optical mode is actually the silent mode attributed to Pb-O stretching bonds within the cubic planes, 26,28 and is related to octahedral tilting. Note that the absence of pressure induced splitting of phonon modes, similar to other PZN-PT compounds, 12,32,25 suggests that there is no change of oxygen environment of Pb. On the other hand, a splitting of this band is observed in PbSc 0.5 Ta 0.5 O 3 , a 1:1 ordered Pb-based relaxor and a change in the local Pb-O environment with pressure is reported.…”

“…37,38 High pressure Raman and diffraction investigations on Pb-based relaxor systems indicate that both local and macroscopic structure are modified under high pressure. 12,32,39,25 In-situ high pressure diffraction and Raman spectroscopic results on pure and A-site doped relaxor PbB ′ 1/2 B ′′ 1/2 O 3 has been reported, 26,27 and it was concluded that pressure suppresses the local polar order and thereby facilitates two successive pressure induced phase transitions below 30 GPa. PZN-PT with x = 0 32 and 0.04, 39 far below the MPB, have been studied by only high pressure Raman spectroscopy and pressure effect on local distortion and their effect on structural transitions were discussed.…”

Twinning and pseudosymmetry under high pressure

“…ZrO 2 [29], chlorpropamide [36], the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [37], the perovskite-like relaxor ferroelectric 0.9 PbZn 1=3 Nb 2=3 O 3 -0.1 PbTiO 3 doped with Ru [38] or FeS [28], yet in all these cases little detail on the behaviour of the twin volume fractions is provided by the authors.…”

X-ray absorption spectroscopy of Ru-doped relaxor ferroelectrics with a perovskite-type structure

“…According to high-precision singlecrystal XRD data on PZN-01.PT at ambient conditions [32], refinements of the unit-cell parameters in a monoclinic metric give a = 4.0306(3)Å, b = 4.0939(3), c = 4.030 20(3)Å, α = 89.96°(1°), β = γ = 90.00°, and a unit-cell volume V = 66.533(9)Å 3 . Thus as initial input crystallographic data for calculating the scattering paths in the EXAFS analysis of PZN-0.1PT-Ru we used a pseudocubic unit-cell parameter a = 3 √ V calculated from the unit-cell volume V of PZN-0.1PT determined by high-precision XRD analysis [32].…”