Universität zu Köln

Ruiz-Fuertes, J., Bayarjargal, L., Winkler, B., Burianek, M. and Muehlberg, M. (2014). Polar nanoregions of Ca0.28Ba0.72Nb2O6 probed by second harmonic generation and Raman spectroscopy at high pressure. Appl. Phys. Lett., 104 (26). MELVILLE: AMER INST PHYSICS. ISSN 1077-3118

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Abstract

The pressure-induced ferroelectric phase transition of calcium barium niobate Ca0.28Ba0.72Nb2O6 is studied by second harmonic generation (SHG) and Raman spectroscopy. We observe the ferroelectric to paraelectric phase transition at P-c = 4 GPa and evidence for two additional local changes at 8.5 and 11.5 GPa that are interpreted as the characteristic intermediate P* and the Burns pressure P-B of a relaxor phase. The pressure dependence of the SHG intensity has a Landau critical exponent of gamma = 1.3 between 4 and 8.5 GPa, indicating the presence of static polar nanoregions. At higher pressures, from 8.5 to 11.5 GPa, these nanoregions become dynamic, with gamma = 2.4, and disappear at 11.5 GPa. The polar nanoregions appear when only one of the two non-equivalent octahedral positions of Nb is centrosymmetric. A Landau exponent of gamma = 1 above 11.5 GPa together with a change in the compression mechanism indicates that the system completes a phase transformation to a centrosymmetric space group and the polar nanoregions vanish. (C) 2014 AIP Publishing LLC.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Ruiz-Fuertes, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bayarjargal, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Winkler, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Burianek, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Muehlberg, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-435605
DOI:	10.1063/1.4885837
Journal or Publication Title:	Appl. Phys. Lett.
Volume:	104
Number:	26
Date:	2014
Publisher:	AMER INST PHYSICS
Place of Publication:	MELVILLE
ISSN:	1077-3118
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FERROELECTRICS; DEPENDENCE; TRANSITION Multiple languages Physics, Applied Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/43560