Berlin 2005 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

DF: Dielektrische Festkörper

DF 9: Phasenüberg
änge und Spektroskopie

DF 9.1: Hauptvortrag

Dienstag, 8. März 2005, 10:00–10:40, TU EMH225

Size effects in BaTiO nanopowders and of BaTiO3 embedded in mesoporous materials — •Dieter Michel, Rolf Boettcher, Emre Erdem, Gert Klotzsche, and Winfried Boehlmann — Leipzig University, Institute of Experimental Physics II, Linnéstrasse 5, 04103 Leipzig

Studies of size effects on ferroelectric properties of oxide perovskites have obtained a great impetus in recent years. EPR and NMR methods can sensitively probe small changes of the local symmetry at the particular crystal sites and, thus, are sensitive to subtle structural short-range changes in nanocrystallites. The main field of this research is the application of multi-frequency EPR to the perovskitic nanocrystallites doped by 3d ions and of quadrupole distorted NMR. Ultrafine powders are prepared through combined-solid state polymerization and pyrolysis (CPP) /1-3/. The CPP prepared oxide perovskite nanopowders were characterized by various methods (TGA, DSC, FT-Raman, XRD, SEM and EDX). Moreover, the behavior of BaTiO3 embedded into mesoporous MCM 41 materials is studied. The lecture intends to give also a survey on recent studies in this field. References: /1/ R. Boettcher et al., 9th Cimtec-World Ceramics Congress, Ceramics: Getting into the 2000s, Part A (1999) 289-292. /2/ H. J. Glaesel et al., J. Mater. Sci. 34(1999)1-5. /3/ E. Erdem et al., J. Mater. Sci. 38 (2003) 3211-3217