A NOVEL FORM OF CD(VO)2(PO4)2 ISOTYPIC WITH CA(VO)2(PO4)2

A second form of the V(IV) phosphate Cd(VO)2(PO4)2 has been isolated. This compound, isotypic with Ca(VO)2(PO4)2, crystallizes in the orthor hombic system, Fdd2, with a = 11.571 (1) angstrom, b = 15.880 (2) angs trom, c = 7.138 (1) angstrom. The structure was established from a sin gle crystal X-ray diffraction study. A complementary description to th at made for Ca(VO)2(PO4)2 is given; large tunnels running along the [1 10] and [110BAR] directions are evidenced. Structural relationships wi th the hexagonal tungsten bronze (HTB) and the NaVPO5 structure are sh own.