Abstract
Pb0.5Ti2(PO4)3 has been prepared from solutions of the corresponding elements. Its crystal structure has been determined in R3 space group, from X-ray powder diffraction data by Rietveld method. Rp=0,10, Rwp=0,13; RB=0,06. The parameters of the equivalent hexagonal cell are ah=8.298±0.004Å and ch=22.70±0.06Å. The structure is formed by a 3D network of TiO6 octahedra and PO4 tetrahedra linked by corners. Pb2+ occupies half of the M1 site in an ordered manner. The Pb-O distance is 2.57Å. TiO6 octahedra are slightly distorted with Ti-O distances of 1.85; 1.87, 1.95 and 2.00Å. PO4 tetrahedra are normal, the P-O distances vary from 1.52 to 1.56; angles vary from 105 to 113°.
