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DF: Dielektrische Festkörper

DF 7: Poster

DF 7.4: Poster

Mittwoch, 26. März 2003, 14:30–18:00, P2a

Fine structure of the OH- stretching vibrational band in Sr_xBa_1−xNb₂O₆ crystals — •C. David¹, A. Tunyagi¹, M. Ulex¹, M. Wöhlecke¹, K. Lengyel², and L. Kovács² — ¹Physics Department, University of Osnabrück, Germany — ²Crystal Physics Department, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege M. út 29-33., Hungary

The stretching mode of the hydroxyl ions in Sr_xBa_1−xNb₂O₆ crystals with x = 0.30 to 0.80 has been measured by the FTIR absorption technique. The absorption band at about 3493 cm⁻¹ was composed of a strong main line and a shoulder as well as additional weak lines on the high energy side. The shape of the shoulder depends strongly on the Sr/Ba ratio of the crystal. This allows a rough estimation of the composition. The main absorption band including the shoulder has been decomposed using Lorentzians and Gaussians and the parameters of four components have been determined. The components are attributed to OH- transitions in different cation environments strongly depending on the crystal composition. The temperature dependence of the OH⁻ absorption band did not reveal the phase transition temperature in the 20-200 ^∘C range.

Support of the Graduate College 695 of the DFG and the project WTZ HUN 01/011 of the DLR is acknowledged.