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A new family of structures: the oxides Ln/sub 4-2x/Ba/sub 2+2x/Zn/sub 2-x/O/sub 10-2x/ (Ln = La, Nd) (in French)

Journal Article · · J. Solid State Chem.; (United States)
Two original compounds, Ln/sub 4-2x/Ba/sub 2+2x/Zn/sub 2-x/O/sub 10-2x/, were isolated for Ln = La, Nd and 0 less than or equal to x less than or equal to 0.25. These oxides are tetragonal with a and c parameters close to 6.91 and 11.59 angstrom, respectively, for lanthanum, and 6.75 and 11.54 angstrom for neodymium. The structure of these phases was determined from X-ray powder patterns in the most symmetric space group, I4/mcm, using Patterson and Fourier functions for x = 0. The structure should be compared to that of copper oxides La/sub 4-2x/Ba/sub 2+2x/Cu/sub 2-x/O/sub 10-2x/: it is built up of identical Ln/sub 2/O/sub 5/ layers formed from face- and edge-sharing LnO/sub 8/ polyhedra, between which Ba/sup 2+/ and Zn/sup 2+/ ions are inserted. Contrary to the copper compounds, two succesive Ln/sub 2/O/sub 5/ layers are rotated by 90/sup 0/, involving a doubling of c. The result of Zn/sup 2+/ is tetrahedral coordination, while the coordination of Ba/sup 2+/ becomes a bicapped antiprism.
Research Organization:
Universite de Caen, France
OSTI ID:
6576793
Journal Information:
J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Journal Issue: 2 Vol. 42:2; ISSN JSSCB
Country of Publication:
United States
Language:
French