Universität zu Köln

Graetsch, H. A., Schreuer, J., Burianek, M. and Muehlberg, M. (2012). Thermally induced structural changes in incommensurate calcium barium niobate Ca0.28Ba0.72Nb2O6 (CBN28). J. Solid State Chem., 196. S. 255 - 267. SAN DIEGO: ACADEMIC PRESS INC ELSEVIER SCIENCE. ISSN 1095-726X

Full text not available from this repository.

Abstract

The incommensurately modulated crystal structure of relaxor ferroelectric CBN28 was refined at elevated temperatures up to 330 degrees C in the 3+2 dimensional superspace group P4bm(alpha alpha 1/2, -alpha alpha 1/2). The structural modulations mainly consisting of cooperative tilting of NbO6 octahedra and an occupational modulation of the large cation site Me2 persist beyond the diffuse ferroelectric transition with slightly reduced amplitudes. A change of symmetry was not observed. Both symmetrically non-equivalent NbO6 octahedra are distorted by off center shifts of the Nb atoms in the same direction along the tetragonal c-axis. The displacements of the Nb atoms are gradually reduced with increasing temperatures until one of the Nb atoms crosses the center of its coordination polyhedron near the transition temperature T-M adopting an uncompensated anti-ferroelectric configuration. This change is accompanied by enhanced thermal motions of the Nb atoms along the c-axis. Structural distortions and electric polarization do not completely vanish at TM but may persist in fluctuating polar nanodomains. (C) 2012 Elsevier Inc. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Graetsch, H. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schreuer, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Burianek, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muehlberg, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-478273
DOI:	10.1016/j.jssc.2012.06.028
Journal or Publication Title:	J. Solid State Chem.
Volume:	196
Page Range:	S. 255 - 267
Date:	2012
Publisher:	ACADEMIC PRESS INC ELSEVIER SCIENCE
Place of Publication:	SAN DIEGO
ISSN:	1095-726X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MODULATED STRUCTURE; COMPOSITION RANGE; CRYSTAL; POLARIZATION; SR0.75BA0.25NB2O6 Multiple languages Chemistry, Inorganic & Nuclear; Chemistry, Physical Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/47827