Dresden 2009 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 6: Poster I
DF 6.9: Poster
Dienstag, 24. März 2009, 09:30–12:30, P5
Influence of rare earth doping on the phase transition characteristic of strontium barium niobate and a comparison to calcium barium niobate — •Alexander Niemer1, Urs Heine1, Uwe Voelker1, Klaus Betzler1, and Manfred Muehlberg2 — 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) shows interesting dielectric properties foremost in the region of its smeared phase transition. Here, the influence of rare earth doping on the relaxor characteristic is studied for SBN by analyzing the complex dielectric constant. As dopants, Erbium (0 to 1.04 mol%), Ytterbium (0 to 1.56 mol%), and Europium (0 to 1.14 mol%) were used. As a result the rare earth doping has significant impact on the phase transition behavior, regarding both, temperature and smearing. Since the use of SBN in technical applications is constrained due to the low phase transition temperature, we analyzed the dielectric behavior of the unfilled tungsten bronze calcium barium niobate (CBN). Congruently melting CBN (28.1 mole fraction calcium [1]) exhibits a phase transition at about 540 K, nearly 200 K higher than the one of SBN61. A comparison between the dielectric constant of SBN and CBN yields, that these two materials show a substantially different phase transition behavior, despite the crystal structures show similarities.
[1] M. Burianek, B. Joschko, I. Kerkamm, T. Schoenbeck, D. Klimm, M. Muehlberg: J. Crystal Growth 229, 413-417 (2007)