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Three modifications of BaCu(SeO/sub 3/)/sub 2/ and the compound SrCu(SeO/sub 3/)/sub 2/: preparation and crystal structure determination

Journal Article · · J. Solid State Chem.; (United States)

The crystal structures of four hydrothermally synthesized alkaline earth-copper-selenites were determined: BaCu(SeO/sub 3/)/sub 2/-I (a = 5.247(1), b = 13.353(2), c = 8.981(1) A, space group Pnm2/sub 1/, Z = 4, R/sub w/ = 0.024 for 1270 reflections), BaCu(SeO/sub 3/)/sub 2/-II (a = 5.256(1), b = 13.231(2), c = 8.933(1) A, ..beta.. = 90.19(1)/sup 0/, space group P2/sub 1//c, Z = 4, R/sub w/ = 0.046 for 2238 reflections), BaCu(SeO/sub 3/)/sub 2/-III (a = 8.0311(1), b = 5.185(1), c = 15.823(2) A, ..beta.. = 90.83(1)/sup 0/, space group C2/c, Z = 4, R/sub w/ = 0.038 for 1866 reflections), and SrCu(SeO/sub 3/)> (a = 7.929(1), b = 5.132(1), c = 14.997(2) A, ..beta.. = 90.53(1)/sup 0/, space group C2/c, Z = 4, R/sub w/ and 0.028 for 1414 reflections; isotypic with BaCu(SeO/sub 3/)/sub 2/-III). BaCu(SeO/sub 3/)-I and -II contain Cu(SeO/sub 3/)/sub 2/ sheets lying parallel to (100) formed by CuO/sub 4/ squares and selenite groups. These sheets are topologically different: in BaCu(SeO/sub 3/)/sub 2/-I they are formed by the connection of Cu/sub 2/(SeO/sub 3/) and Cu/sub 6/(SeO/sub 3/)/sub 4/ rings while in BaCu(SeO/sub 3/)/sub 2/-II they are formed by Cu/sub 2/(SeO/sub 3/)/sub 2/ and Cu/sub 6/(SeO/sub 3/)/sub 6/ rings. The Cu(SeO/sub 3/)/sub 2/ sheets are rugged in BaCu(SeO/sub 3/)/sub 2/-I and they are slightly waved in BaCu(SeO/sub 3/)/sub 2/-II. In both compounds they are connected to each other by a fifth Cu-O bond and by the Ba atoms. In BaCu(SeO/sub 3/)/sub 2/-III and in its isotypic Sr analog the CuO/sub 4/ squares and the selenite groups form parallel chains (010), which are connected by the alkaline earth atoms.

Research Organization:
Universitaet Wien, Austria
OSTI ID:
5775136
Journal Information:
J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 70:2; ISSN JSSCB
Country of Publication:
United States
Language:
English