Synthesis, crystal structure, and vibrational spectra of Ca4P6O19 (Tromelite) - a catena-hexaphosphate

The catena-hexaphosphate Ca4P6O19 (Tromelite) was obtained by the reaction of calcium oxide with H3PO3 in a tube furnace at a temperature of 900 ° C and crystallizes triclinic (space group P (1) over bar, Z = 2, a = 685.70(9) pm, b = 915.47(12) pm, c = 1282.25(17) pm, α = 109.602(10)°, β = 99.778(10)°, γ = 91.917(10)°, V = 743.70(17)• 10(6) pm(3)). According to the powder diffraction data of Ca4P6O19 a Rietveld refinement of the lattice constants was performed; this confirmed the single-crystal data. Tromelite contains chains of six condensed corner-sharing PO4 tetrahedra with the Ca atoms in the voids of the resulting structure. IR and Raman data of Tromelite are also presented.