College Park, Maryland      June 6 - 10 , 2004

TP10: Octahedral Tilting Distortions in 2:1 B-site Ordered Perovskites

Michael Lufaso (Ceramics Division, MSEL, National Institute of Standards and Technology)

Perovskite materials that exhibit a 2:1 ordered cation arrangement and also undergo an octahedral tilting distortion exhibit interesting changes in the temperature dependence of the dielectric properties, when compared to the untilted 2:1 ordered perovskites (e.g. Ba3ZnTa2O9). The onset of octahedral tilting in the 2:1 B-site cation ordered perovskites is well-known to influence the physical properties; however the crystal structures have not been reported. Polycrystalline samples of Sr3MM'2O9 (M = Mg, Ni; M' = Nb, Ta) were synthesized and neutron powder diffraction data were collected, at the High-Intensity Powder Diffractometer at the Los Alamos Neutron Science Center, as a function of temperature. The structural parameters, obtained from a neutron time-of flight data analysis via Rietveld refinement, are compared.

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