Synthesis and crystal structure determination of yttrium ultraphosphate YP5O14

The crystal structure of monoclinic YP5O14 (space group C2/c, a=12.919(2) Å, b=12.796(4) Å, c=12.457(2) Å, β=91.30(1)°, Z=8) has been refined from single-crystal X-ray diffraction data. Full-matrix least-squares refinement on F2 using 2249 independent reflections for 183 refinable parameters results in a final R value of 0.027 (ωR=0.069). The structure is isotypic with HoP5O14. This structure is built up from infinite layers of PO4 tetrahedra linked through isolated YO8 polyhedra. The three-dimensional cohesion of the framework results from Y–O–P bridges. This crystal structure refinement leads to the calculated X-ray diffraction powder pattern of this monoclinic polymorph, which has been the starting point of a thorough study of the solid-state synthesis of this ultraphosphate. This investigation further leads to a better outstanding of features observed during the synthesis of powdered samples. The thermal behavior of this ultraphosphate has been studied by DTA and TGA analyses. The infrared and Raman spectroscopic characterizations have been carried out on polycrystalline samples. The luminescence properties of the Eu3+ ion incorporated in the monoclinic C2/c polymorph of YP5O14 as local structural probe show that in YP5O14: 5% Eu3+ sample, the Eu3+ ions are distributed over the two Y3+ crystallographic sites of C2 symmetry of this structure.