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Title: Local structure of the lead-free relaxor ferroelectric (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3}

Abstract

The local environment of Bi and Ti atoms in the lead-free relaxor ferroelectric solid-solution (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3} has been studied as a function of K concentration and as a function of temperature for the x=0 end member by x-ray absorption fine structure (XAFS). It is found that the local environment of Bi is much more distorted than that determined from conventional diffraction experiments. The shortest Bi-O distances are determined to be 2.22 A, and are 0.3 A shorter than those calculated from the crystallographic data. Several possible models of the Bi coordination environment, which are consistent with the XAFS data and provide bond-valence sums for Bi that are closer to the theoretical values, are proposed. The Ti displacement from the center of the oxygen octahedron increases with K concentration while the shortest Bi-O distance shows no compositional dependence. In K{sub 0.5}Bi{sub 0.5}TiO{sub 3} the value of the Ti displacement is determined to be 0.18 A. The changes of the macroscopic symmetry at the phase transition points in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} do not lead to changes of the radial atomic distribution around Ti, which is well off-center over the whole temperature range up to and including themore » paraelectric cubic phase. The results can be explained by assuming the presence of structural disorder.« less

Authors:
; ; ; ; ; ;  [1]
  1. Clarendon Laboratory, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom)
Publication Date:
OSTI Identifier:
20718992
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 71; Journal Issue: 17; Other Information: DOI: 10.1103/PhysRevB.71.174114; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTROSCOPY; ATOMS; BISMUTH COMPOUNDS; CRYSTAL STRUCTURE; DISTRIBUTION; FERROELECTRIC MATERIALS; FINE STRUCTURE; OXYGEN; PHASE TRANSFORMATIONS; POTASSIUM COMPOUNDS; SODIUM COMPOUNDS; SOLID SOLUTIONS; TEMPERATURE DEPENDENCE; TITANATES; VALENCE; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY

Citation Formats

Shuvaeva, V A, Zekria, D, Glazer, A M, Jiang, Q, Weber, S M, Bhattacharya, P, Thomas, P A, and Department of Physics, University of Warwick, Coventry CV4 7AL. Local structure of the lead-free relaxor ferroelectric (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3}. United States: N. p., 2005. Web. doi:10.1103/PhysRevB.71.174114.
Shuvaeva, V A, Zekria, D, Glazer, A M, Jiang, Q, Weber, S M, Bhattacharya, P, Thomas, P A, & Department of Physics, University of Warwick, Coventry CV4 7AL. Local structure of the lead-free relaxor ferroelectric (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3}. United States. https://doi.org/10.1103/PhysRevB.71.174114
Shuvaeva, V A, Zekria, D, Glazer, A M, Jiang, Q, Weber, S M, Bhattacharya, P, Thomas, P A, and Department of Physics, University of Warwick, Coventry CV4 7AL. Sun . "Local structure of the lead-free relaxor ferroelectric (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3}". United States. https://doi.org/10.1103/PhysRevB.71.174114.
@article{osti_20718992,
title = {Local structure of the lead-free relaxor ferroelectric (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3}},
author = {Shuvaeva, V A and Zekria, D and Glazer, A M and Jiang, Q and Weber, S M and Bhattacharya, P and Thomas, P A and Department of Physics, University of Warwick, Coventry CV4 7AL},
abstractNote = {The local environment of Bi and Ti atoms in the lead-free relaxor ferroelectric solid-solution (K{sub x}Na{sub 1-x}){sub 0.5}Bi{sub 0.5}TiO{sub 3} has been studied as a function of K concentration and as a function of temperature for the x=0 end member by x-ray absorption fine structure (XAFS). It is found that the local environment of Bi is much more distorted than that determined from conventional diffraction experiments. The shortest Bi-O distances are determined to be 2.22 A, and are 0.3 A shorter than those calculated from the crystallographic data. Several possible models of the Bi coordination environment, which are consistent with the XAFS data and provide bond-valence sums for Bi that are closer to the theoretical values, are proposed. The Ti displacement from the center of the oxygen octahedron increases with K concentration while the shortest Bi-O distance shows no compositional dependence. In K{sub 0.5}Bi{sub 0.5}TiO{sub 3} the value of the Ti displacement is determined to be 0.18 A. The changes of the macroscopic symmetry at the phase transition points in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} do not lead to changes of the radial atomic distribution around Ti, which is well off-center over the whole temperature range up to and including the paraelectric cubic phase. The results can be explained by assuming the presence of structural disorder.},
doi = {10.1103/PhysRevB.71.174114},
url = {https://www.osti.gov/biblio/20718992}, journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 17,
volume = 71,
place = {United States},
year = {2005},
month = {5}
}