Regensburg 2007 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 11: Poster Session
DF 11.23: Poster
Donnerstag, 29. März 2007, 14:30–18:00, Poster C
Local structural phenomena in Ba-containing PbSc0.5B"0.5O3 (B"=Ta, Nb) — •Anna-Maria Welsch1, Boriana Mihailova1, Thomas Malcherek1, Bernd Guettler2, Carsten Paulmann1, Marin Gospodinov3, and Ulrich Bismayer1 — 1Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, D-20146 Hamburg, Germany — 2PTB, Bundesallee 100, D-38116 Braunschweig, Germany — 3ISSP-BAS, Blvd. Tsarigradsko Chausse 72, 1784 Sofia, Bulgaria
Relaxor-ferroelectric state is characterized by the existence of nano-scale polar clusters of different size and shape distributed inside a paraelectric matrix. Best known materials with relaxor-ferroelectric properties are Pb-based perovskite-type complex oxides of the general formula ABO3. The perovskite structure enables ion substitutions on both A- and B-sites. Variations in the chemical composition influence the nano-domain structure and thus allow enhancement of the desired relaxor properties. Here we present our results on the structure of Ba-containing PbSc0.5(Ta,Nb)0.5O3. The structural changes caused by the A-site doping were studied by complementary application of single-crystal X-ray diffraction and polarized Raman spectroscopy. The loading of stereochemically non-active ions causes lattice distortions and changes in the local symmetry. Our results indicate fragmentation of the ferroic clusters in the host matrix by breaking the pattern of Pb2+ off-centre shifts and generation of new ferroic species.