Crystal Data for Two Molybdates MIV(MoO4)2 With MIV= Zr, Hf

Two molybdates MIV(MoO4)2 (with MIV = Hf or Zr) were synthesized by solid state reaction between MIVO2 and MoO3. Zirconium molybdate undergoes a reversible phase transition at 952 K. Hf(MoO4)2 and H.T. Zr(MoO4)2, obtained as single crystals, are trigonal, space group P31c with Z = 6; the cell dimensions are respectively a = 10.1005(3), c = 11.7230(5)Å V = 1035.76(11)Å3; Dm(298 K) = 4.78(4), Dx = 4.792 Mg m-3 and a = 10.1409(3), c = 11.7097(5)Å V = 1042.88(11)Å3; Dm (298 K) = 3.91(4), Dx = 3.926 Mg m-3. L.T. Zr(MoO4)2, indexed by the Visser automatic indexing program (1969) was found to be monoclinic, possible space group P2, P21 or Pm with Z = 4; the cell dimensions are a - 9.7557(5), b = 7.9373(5), c = 7.4631(4)Å, β = 97.959°(5); V = 572.3(5)Å Dm(298 K) - 4.74(5), Dx = 4.770 Mg m−3. Powder diffraction data were obtained at 293 K on a counter diffractometer with Ni-filtered copper radiation (̄λ = 1.5418 Å). © 1987, Cambridge University Press. All rights reserved.