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DF: Fachverband Dielektrische Festkörper

DF 11: Poster Session

DF 11.20: Poster

Donnerstag, 29. März 2007, 14:30–18:00, Poster C

Conical light scattering in strontium barium niobate crystals related to an intrinsic composition inhomogeneity — Kathrin Bastwöste, Uwe Sander, and •Mirco Imlau — Fachbereich Physik, Universität Osnabrück, Barbarastraße 7, 49069 Osnabrück

Conical light scattering is uncovered in poly- and mono-domain, nominally pure and Eu-doped strontium barium niobate (SBN) crystals over a wide temperature regime. The appearance of two scattering cones, a scattering line and a corona is observed and can be explained comprehensively within the Ewald sphere concept. Photorefraction, scattering from domain boundaries or from growth striations can be well excluded to explain the origin of the scattering. It is shown that the temperature-resistant scattering process is related to a growth-induced seeding rod, i. e., a composition inhomogeneity primarily localized in the center of the SBN sample. The rod is directed parallel to the polar axis and yields a refractive-index modulation with spatial frequencies on the micro-scale. The significant impact in the frame of material analysis is reflected by the possibility of phase-transition studies of the relaxor-ferroelectric SBN up to temperatures as high as 750 K.
Financial support by the DFG (GRK 695) is gratefully acknowledged.