E. Le Fur and J. Y. Pivan
The new lamellar vanadium(IV) phosphate β-Pb(VOPO4)2·4H2O has been isolated and X-ray single crystal diffraction data gave an orthorhombic cell [space group P212121, Z = 4; a = 6.377(9), b = 6.384(1), c = 25.357(11) Å]. The structure, solved by using direct methods and refined to the reliability factors R1 = 0.027 (wR2 = 0.074), is a stacking variant of the monoclinic derivative Pb(VOPO4)2·4H2O described previously. Magnetic measurements in the range 3–300 K give a magnetic moment consistent with V(IV) cations with weak antiferromagnetic interactions below 6 K. Crystal chemical relationships with related M(VOPO4)2·yH2O phosphates are also discussed.