Phase transitions in lead-free piezoelectric ceramics: Study of local atomic structure

M. P. Lemeshko; E. S. Nazarenko; A. A. Gonchar; L. A. Reznichenko; O. Mathon; Y. Joly; R. V. Vedrinskii

doi:10.1209/0295-5075/77/26003

All issues

Volume 77 / No 2 (January 2007)

EPL, 77 2 (2007) 26003

Abstract

This article has an erratum: [https://doi.org/10.1209/0295-5075/77/59901]

Issue		EPL Volume 77, Number 2, January 2007


Article Number		26003
Number of page(s)		5
Section		Condensed Matter: Structural, Mechanical and Thermal Properties
DOI		https://doi.org/10.1209/0295-5075/77/26003
Published online		11 January 2007

EPL, 77 (2007) 26003

Phase transitions in lead-free piezoelectric ceramics: Study of local atomic structure

M. P. Lemeshko¹, E. S. Nazarenko¹^,2, A. A. Gonchar¹, L. A. Reznichenko¹, O. Mathon³, Y. Joly² and R. V. Vedrinskii¹

¹ Institute of Physics, Rostov State University - 194 Stachky Ave., 344090 Rostov-on-Don, Russia
² Laboratoire de Cristallographie, CNRS associé à l'Université Joseph Fourier - BP 166, F-38042 Grenoble Cedex 9, France
³ BM29, European Synchrotron Radiation Facility - BP 220, F-38043 Grenoble Cedex 9, France

Received: 16 August 2006
Accepted: 20 November 2006

Abstract

Local atomic structure of the piezoelectric ceramics ${\rm K}_{x}{\rm Na}_{1-x}{\rm NbO}_{3}$ ( $x=0.00, 0.05, 0.30, 0.40, 0.50$ and 0.65) is studied in all phase regions (10 K $\hbox{--}$ 1023 K) using Nb K-edge extended X-ray absorption fine-structure (EXAFS) spectroscopy. We have shown the validity of a new spherical model for phase transitions on the basis of both fitting of EXAFS signal in the R-space and differential EXAFS analysis. Within this model the Nb atoms are located on the surfaces of small spheres of constant radii surrounding centers of ${\rm NbO}_{6}$ octahedrons in all phases. The distri- bution of the Nb atom on this surface changes during phase transitions. Besides, the analysis of local structure reveals that the geometry of ${\rm NbO}_{6}$ octahedra does not depend on the x value at each temperature, whereas the octahedra rotation angles do.

PACS: 61.10.Ht – X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. / 77.84.Dy – Niobates, titanates, tantalates, PZT ceramics, etc. / 64.90.+b – Other topics in equations of state, phase equilibria, and phase transitions

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