STRUCTURE OF CUZR2(PO4)3 BY X-RAY AND NEUTRON POWDER DIFFRACTION

Copper(I) dizirconium monophosphate. CuZr2(PO4)3, M(r) = 530.90, trigonal, R3cBAR, Z = 6. structure refined with powder diffraction methods. X-ray diffraction: lambda(Cu Kalpha) = 1.54184 angstrom, F(000) = 1500, room temperature, a = 8.9018 (2), c = 22.2021 (6) angstrom, V = 1523.6 (1) angstrom3, D(x) = 3.47 Mg m-3, R(p) = 0.039, R(I) = 0.047, 231 reflections. Neutron diffraction: lambda = 1.594 angstrom, F(000) = 642.06 fm, room temperature, a = 8.892 (1), c = 22.190 (1) angstrom, V = 1519.5 (3) angstrom3. D(x) = 3.48 Mg m-3, R(p) = 0.056. R(I) = 0.091. The atomic arrangement is a three-dimensional skeleton involving ZrO6 octahedra and PO4 tetrahedra sharing common corners. The Cu environment is a compromise between the usual linear coordination of Cu(I) and the antiprismatic surrounding of the M(1) site within the three-dimensional Zr2(PO4)3 framework. Existence of Cu(I)-Cu(I) pairs within M(1) is discussed with respect to the luminescent properties. The JCPDS File No. for CuZr2(PO4)3 is 43-1495.