The crystal structure of Ba{sub 8}Ta{sub 6}NiO{sub 24}: Cation ordering in hexagonal perovskites

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1996.0270· OSTI ID:450706

Abakumov, A M; Van Tendeloo, G; Scheglov, A A ^[1]

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1. Univ. of Antwerp (Belgium)

The new complex perovskite-like oxide Ba{sub 8}Ta{sub 6}NiO{sub 24} was synthesized and its crystal structure was studied using X-ray powder diffraction, electron diffraction, and high resolution electron microscopy. The Ba{sub 8}Ta{sub 6}NiO{sub 24} structure is based on a 8H (cchc){sub 2} close-packed stacking of BaO{sub 3} layers (space group P6{sub 3}cm, a = 10.07458(6) {angstrom}, c = 19.0122(2) {angstrom}.). The structural refinement gave the following values of reliability factors: R{sub F} = 0.028, R{sub p} = 0.042, R{sub wP} = 0.056. The main feature of this structure is the existence of two different pairs of face-sharing octahedra. In the first pair one octahedron is occupied by Ta whereas the other one is empty. In the second pair one of the two octahedra is occupied by Ta and a cation vacancy and its neighbor is occupied by Ni, Ta, or a vacancy. This distribution of cations was completely confirmed by electron microscopy. The formation of a Ba{sub 8}Ta{sub 6+0.4x}Ni{sub 1-x}O{sub 24} solid solution with a narrow homogeneity range with (-0.2 {le} {times} {le} 0.2) was observed.

• OSTI ID: 450706
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 125; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
BARIUM OXIDES
CRYSTAL STRUCTURE
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
NICKEL OXIDES
TANTALUM OXIDES
X-RAY DIFFRACTION