Defect-Dipole Formation in Copper-Doped PbTiO3 Ferroelectrics
-
Autor:
Eichel, RA; Erhart, P; Träskelin, P; Albe, K; Kungl, H; Hoffmann, MJ
-
Quelle:
PHYSICAL REVIEW LETTERS, 2008, Band 100, Heft 9, S. 95504-95700
Abstract
The defect structure of hard copper-modified polycrystalline PbTiO3
ferroelectrics is investigated by means of electron paramagnetic
resonance and hyperfine sublevel correlation spectroscopy, as well as
density functional theory calculations. Special emphasis is put on the
Pb-207-hyperfine couplings, which are resolved up to the third
coordination sphere. The results prove that copper is incorporated at
the octahedrally coordinated Ti site, acting as an acceptor. Because of
charge compensation the formation of Cu impurity-oxygen vacancy pairs is
energetically very favorable. The corresponding (Cu-Ti ''-V-O(center
dot center dot))(x) defect dipole is found to be orientated along the
[001] axis.