Crystal structure of calcium cobalt orthophosphate, CaCo[Ca0.1Co0.9](PO4)2

Crystal structure of Ca1.1Co1.9(PO4)(2) was successfully determined from laboratory X-ray powder diffraction data (Co K alpha) using direct methods and the Rietveld refinement. The crystal structure was found to be monoclinic (space group P2(1)/n, Z = 4) with lattice dimensions of a = 1.452 67(5) nm, b=0.49434(1)nm, c=0.86750(3)nm, beta = 92.316(1)degrees, and V=0.62245(3)nm(3). The final reliability indices calculated from the Rietveld refinement were R-wp=3.93%, R-p=3.02%, R-B =4.10%, and S=1.48. Both Co and Ca atoms were distributed over the 2a and 2d sites with a preference of Ca at the 2d site. The coexistence of Co and Ca on the 2a and 2d sites is indispensable for stabilizing Ca1.1Co1.9(PO4)(2) in the Ca-3(PO4)(2)-Co-3(PO4)(2) system. (C) 2006 International Centre for Diffraction Data.