New insight into the symmetry and the structure of the double perovskites Ba{sub 2}LnNbO{sub 6} (Ln=lanthanides and Y)
- Gorlaeus Laboratories, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (Netherlands)
Structures of the double perovskites Ba{sub 2}LnNbO{sub 6} (Ln=La, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Y) at room temperature have been re-examined by Rietveld profile analysis of X-ray diffraction data. It was shown that the correct phase sequence across the lanthanides is I2/m (Ln=La, Pr, Nd, and Sm), I4/m (Ln=Eu, Gd, Tb, and Dy), and Fm3-bar m (Ln=Ho and Y), respectively. All phases can be derived from the ideal cubic perovskite by ordering the Ln(III) and Nb(V) ions and by out-of-phase tilting the LnO{sub 6}/NbO{sub 6} octahedra around either the primitive two-fold [110]{sub p}-axis (I2/m) or the four-fold [001]{sub p}-axis (I4/m). The monoclinic P2{sub 1}/n structure that contains both out-of-phase and in-phase tilt around the primitive [110]{sub p}- and [001]{sub p}-axis, respectively, has not been observed for this series of compounds.
- OSTI ID:
- 20784952
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 4; Other Information: DOI: 10.1016/j.jssc.2005.12.031; PII: S0022-4596(05)00627-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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