Notizen: Die Kristallstruktur von Calciumchromat(VI), CaCrO4 / The Crystal Structure of Calcium Chromate (VI), CaCrO4

The zircon-type structure of calcium chromate( VI), CaCrO4, has been confirmed and refined from single-crystal X-ray data. The compound crystallizes tetragonaly, space group I41/amd, with a = 7.222(2), c = 6.285(1) Å, c/a = 0.8703 and Z = 4. The structure comprises isolated, slightly distorted CrO4 tetrahedra ( C r-O = 1.646(3) Å ) which are connected with CaO8 dodecahedra ( = 2.556 Å) by edge- and corner-sharing. The three-dimensional framework thus created contains rather large holes which are, however, empty in the case of CaCrO4