Regensburg 2007 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 3: Relaxor Ferroelectrics
DF 3.3: Vortrag
Montag, 26. März 2007, 15:30–15:50, H11
Relaxor ferroelectrics: ferroic clustering and phonon anomalies — •Boriana Mihailova1, Anna-Maria Welsch1, Bernd Guettler2, Marin Gospodinov3, and Ulrich Bismayer1 — 1Mineralogisch-Petrographisches Institut, Universität Hamburg, Grindelallee 48, D-20146 Hamburg — 2PTB, Bundesallee 10, D-38116 Braunschweig — 3ISSP-BAS, Blvd. Tzarigradsko Chausse 72, 1784 Sofia
Relaxor ferroelectrics are among the key materials in modern solid-state science due to their outstanding dielectric, electro-optic, and electro-elastic properties. Because of their complex local structure studies on the relaxor structure require the application of fine-scale structure-sensitive methods as inelastic light scattering, in addition to the conventional diffraction methods. Here we report on the relationship between the observed phonon anomalies and the local atomic arrangements in Pb-based perovskite-type relaxors studied on the basis of model representative lead scandium tanatalates/niobates doped with various elements. It is shown that the ferroic clustering and the development of ferroelectric state can be followed by analysing quantitatively the intensity ratios of the Raman scattering arising from the corresponding local structural distortions. The presence of point defects such as oxygen vacancies and incorporation of additional elements in the cation positions heavily influences the incipient ferroic species and suppresses the formation of proper ferroelectric state, thus favouring the non-ergodic state.