XAFS study of the phase transitions in relaxor ferroelectrics
Abstract
The temperature-dependent Nb K-XAFS spectra of several mixed Pb-containing perovskite compounds, such as PbNb1/2Sc1/2O3, PbNb1/2In1/2O3 and PbNb2/3Zn1/3O3 were analyzed to determine Nb displacement and to trace its changes through the diffuse phase transition from the low-temperature ferroelectric to the high-temperature paraelectric phase. Nb displacement was evaluated on the basis of both EXAFS and the pre-edge structure. The x-ray diffraction data for ordered antiferroelectric modification of PbNb1/2In1/2O3 were also involved in analysis. The results shows, that in all the structures Nb occupy an off-center position which symmetry is lower than that implied by macroscopic symmetry. Both value and direction of the Nb off-center displacement don’t display any noticeable temperature change and aren’t affected by the change of macroscopic symmetry.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARH33124S