Synthesis and structural investigations on the new Sr1.32Mn0.83CU0.17O3 compound

The Sr1.32Mn0.83Cu0.17O3 compound has been prepared by solid state reaction in an evacuated sealed silica tube at 1000degreesC. The crystal structure of Sr1.32Mn0.83Cu0.17O3 was studied by means of electron diffraction, high resolution electron microscopy and was refined from X-ray powder diffraction data (R-I = 0.042, R-P = 0.016). The compound belongs to the A(3m+3n)A(n)'B3m+nO9m+6n, family of hexagonal perovskites. Its incommensurate composite structure (a = 9.5964(1) Angstrom, c = 2.6001(1) Angstrom, q = 0.66159(3)c*, superspace group R (3) over barm(00gamma)0s) consists of the modulated [(Mn,Cu)O-3](infinity) and [Sr](infinity) subsystems. The repeat period along the [(Mn,Cu)O-3](infinity) chains of the BO6 octahedra and the A'O-6 trigonal prisms is equal to 99 polyhedra and can be represented as a sequence of 1 x (3 oct + 1 prism) and 9 x (2 oct + 1 prism) or 10 x (2 oct + 1 prism). Mn is located at the octahedral sites, whereas the trigonal prismatic sites are randomly occupied by Mn and Cu. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.