Powder diffraction data for niobium IV hexafluorides: VNbF_6 and CrNbF_6

摘要

New hexafluoroniobates IV, VNbF_6 and the high-temperature form of CrNbF_6 have been synthesized by solid-state reaction. The former is isostructural with rhomobohedral LiSbF_6, space group R_3, and the latter crystallizes with tetragonal symmetry, space group I/4mmm. Unit-cell parameters were determined: a=5.520 (1)A, c=13.987(5)A, V=369.0(1) A~3, Z=3 for VNbF_6, and a=5.5403(5)A, c=8.453(1) A, V=259.5(1) A~3, Z=2 for the "HT" form of CrNbF_6. Powder diffraction data are reported.