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New mixed-valence chromium structure type: NH4Cr(CrO4)2

Barbara M. Casari ; Erica Wingstrand ; Vratislav Langer (Institutionen för kemi- och bioteknik, Oorganisk miljökemi)
Journal of Solid State Chemistry (0022-4596). Vol. 179 (2006), 1, p. 296-301.
[Artikel, refereegranskad vetenskaplig]

Synthesis and crystal structure of a new structure type of mixed Cr(III)/Cr(VI) chromates is reported. NH4Cr(CrO4)2 was prepared from CrO3 in the presence of (NH4)2Ce(NO3)6. Since this is the first preparation of mixed valence ternary chromium oxides from aqueous solution, a reaction pathway for this synthesis is suggested. The crystal structure of NH4Cr(CrO4)2 has been determined from three-dimensional X-ray data collected at low temperature, 173 K. The structure belongs to the orthorhombic space group Pnma, with a=14.5206(10), b=5.4826(4), c=8.7041(7) Å and Z=4. The title compound consists of corner-sharing chromium(III) octahedra and chromium(VI) tetrahedra forming a three-dimensional network with the composition [Cr(CrO4)2]n, containing channels in which zigzag rows of ammonium ions balance the net charge.

Nyckelord: NH4Cr3O8, mixed-valence ternary oxide, mixed valence chromate, Cr(VI)/Ce(III) redox reaction, X-ray diffraction

Denna post skapades 2006-08-25. Senast ändrad 2013-06-03.
CPL Pubid: 11315


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Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)


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