Europhys. Lett., 61 (5) , pp. 653-659 (2003)
Observation of a sample-dependent 37 anomaly on the lattice parameters of strontium titanateL. Arzel1, 2, B. Hehlen1, F. Dénoyer3, R. Currat2, K.-D. Liss4 and E. Courtens1
1 Laboratoire des Verres, UMR 5587 CNRS, Université Montpellier II F-34095 Montpellier Cedex 5, France
2 Institut Laue-Langevin - BP 156, F-38042 Grenoble Cedex 9, France
3 Laboratoire de Physique des Solides, UMR 8502 CNRS, Université Paris-Sud F-91405 Orsay Cedex, France
4 European Synchrotron Radiation Facility BP 220, F-38043 Grenoble Cedex, France
(Received 5 August 2002; accepted in final form 16 December 2002)
The lattice parameters of tetragonal strontium titanate are determined to about 1 part in 106 with penetrating X-rays. While no peculiarity is detected in a bulk sample, a distinct anomaly at 37 is observed in an optically polished thin platelet derived from the same single crystal. This suggests that the anomaly is related to a high density of dislocations. A possible mechanism is that dislocations stabilize transverse antiphase boundaries which undergo a ferroelectric transition near 37 . If so, this transition stresses the boundaries which then strain the bulk leading to the observed anomaly.
61.50.Ks - Crystallographic aspects of phase transformations; pressure effects.
77.84.Dy - Niobates, titanates, tantalates, PZT ceramics, etc.
61.10.-i - X-ray diffraction and scattering.
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