Subsolidus phase relations in Na2O-CuO-Sb2On system and crystal structure of new sodium copper antimonate Na3Cu2SbO6

摘要

Subsolidus phase relation studies in the NaSb3O7-Na3SbO4-CuO-CuSb2O6 quadrangle of Na2O-CuO-Sb2On system at 1123-1173 K revealed the formation of one new compound Na3Cu2SbO6. It is a superstructure derived from alpha-NaFeO2 type, space group C2/m, lattice constants: a = 5.6759(1) angstrom, b = 8.8659(1) angstrom, c = 5.8379(1) angstrom, beta = 113.289(1)degrees. All ions are in octahedral environment, but CuO6 polyhedron exhibits strong elongation due to Jahn-Teller effect (Cu-O: 2.000(2) angstrom x 2, 2.021(2) angstrom x 2, 2.494(3) angstrom x 2), whereas SbO6 octahedron is almost regular. The relationship to other similar superlattices is discussed. (c) 2005 Elsevier Inc. All rights reserved.