Berlin 2008 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 9: Poster
DF 9.10: Poster
Dienstag, 26. Februar 2008, 15:00–18:00, Poster G
Investigation of the uniaxial relaxor calcium barium niobate by k-space spectroscopy and pyroelectric methods: a comparison to strontium barium niobate. — •Urs Heine1, Uwe Völker1, Klaus Betzler1, Manfred Burianek2, and Manfred Mühlberg2 — 1University of Osnabrück, Department of Physics, Barbarastr. 7, 49076 Osnabrück — 2University of Cologne, Institute of Crystallography, Zülpicher Str. 49b, 50674 Cologne
The ferroic relaxor strontium barium niobate (SBN) has been considered as a promising material for optical applications, but the low phase transition temperature region prevents reliable utilization of its ferroelectric characteristics. Here, we present comparative investigations of the unfilled tungsten bronze calcium barium niobate (CBN) using k-space spectroscopy and pyroelectric measurements. Contrary to SBN, CBN shows a limited stability region in the range of about 20 and 40 mole fraction calcium. Congruently melting CBN (28.1 mole fraction calcium [1]) shows a relaxor phase transition analog to that in SBN at approximately 540 K, 200 K higher than that of SBN61. By applying external electric fields to CBN, we find similar behaviour as for SBN [2], even though the anisotropy in the distribution of the domain-sizes arises at higher fields. Thus, we conclude that CBN - like SBN - exhibits a domain size dependent ferroelectric characteristic, too.
[1] M. Burianek, B. Joschko, I. Kerkamm, T. Schoenbeck, D. Klimm, M. Muehlberg: J. Crystal Growth 229, 413-417 (2007)
[2] U. Voelker, U. Heine, C. Gödecker, K. Betzler: Journal of Applied Physics: in print (2007)