Low temperature synthesis and characterization of Na-M-(O)-F phases with M=Ti, v

© 2015 Elsevier Inc.All rights reserved. Na5Ti3O3F11 was prepared by the microwave assisted method, and presents a chiolite related structure with cell parameters a=10.5016(5), b=10.4025(5), and c=10.2911(5) Å and Cmca (no. 64) space group. From solvothermal synthesis at 100°C the cryolite Na3-δVO1-δF5+δ was prepared, which crystallizes in the monoclinic system with a=5.5403(2), b=5.6804(2), c=7.9523(2) Å, β=90.032(7)°cell parameters and P21/n (no. 14) space group. Under similar synthesis conditions but with higher HF concentration the chiolite-type phase Na5-δV3F14 was achieved, which exhibits a=10.5482(2), b=10.4887(1) and c=10.3243(1) Å cell parameters and Cmc21 (no. 36) space group. A single crystal also having the chiolite structure was synthesized at 200°C which exhibits tetragonal symmetry (a=7.380(3) and c=10.381(11) Å and space group P42212 (no. 94)). Bond valence sum indicates that it contains V4+ and therefore can be formulated as Na5V3O3F11.