The nature of iron-oxygen vacancy defect centers in PbTiO3

2005/04/27 by H. Mestric, R. -A. Eichel, T. Kloss +7
Physics and Astronomy · #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevb.71.134109

published as Phys. Rev. B 71, 134109 (2005) · 11 pages, 5 figures, accepted in Phys. Rev. B

arxiv created 2005/04/27 · arxiv updated 2009/12/01

Abstract

The iron(III) center in ferroelectric PbTiO3 together with an oxygen vacancy forms a charged defect associate, oriented along the crystallographic c-axis. Its microscopic structure has been analyzed in detail comparing results from a semi-empirical Newman superposition model analysis based on finestructure data and from calculations using density functional theory. Both methods give evidence for a substitution of Fe3+ for Ti4+ as an acceptor center. The position of the iron ion in the ferroelectric phase is found to be similar to the B-site in the paraelectric phase. Partial charge compensation is locally provided by a directly coordinated oxygen vacancy. Using high-resolution synchrotron powder diffraction, it was verified that lead titanate remains tetragonal down to 12 K, exhibiting a c/a-ratio of 1.0721.

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