FOUR-DIMENSIONAL INCOMMENSURATELY MODULATED STRUCTURE OF THULIUM POLYPHOSPHATE

Single crystal of rare-earth polyphosphate Tm(PO3)(3) has been grown under high temperature molten-salt method and structurally characterized by single crystal X-ray diffraction analysis. Using the four-dimensional superspace formalism for aperiodic structures, we performed the crystal structure refinement of Tm(PO3)(3) as (3+ 1)-dimensional incommensurately modulated structure with monoclinic superspace group C2/c(0, 0.358,0)s0 and a = 14.0620 (12)angstrom, b = 6.6612 (6) angstrom, c = 10.0191 (9) angstrom, beta = 127.6043 (9)degrees, V = 743.51 (11) angstrom(3), Z = 4, M-r = 405.8, D-c = 3.626 g/cm(3), F(000) = 744, mu((MoKa)) = 12.60 mm(-1), R = 0.048 and omega R = 0.050. The structure features infinite chains of corner-sharing PO4 tetrahedra which are affected by positional modulation running along the b-axis. The final structure model was reasonable and did not show any unusual features.