X-ray powder structure determination of Li6P6O18·3H2O

Abstract

Preparation, characterization by X-ray diffraction, IR absorption, DTA-GTA analysis and ab-initio crystal structure determination are reported for a new lithium cyclohexaphosphate hydrate Li₆P₆O₁₈·3H₂O. It crystallizes in a trigonal (rhomboedral) cell (space group R 3¯m No 166, Z = 6) with a = 15.7442(2) Å, c = 12.5486(2) Å. X-ray powder diffraction pattern data was refined by Rietveld profile technique and lead to R_Bragg = 0.09. The crystal structure of Li₆P₆O₁₈·3H₂O is built up from [P₆O₁₈]^6- ring anions, having the 3m symmetry, alternating along the 3¯ axis with rings made of six LiO₄ tetrahedra and six LiO₅ pseudo square pyramids sharing common edges.