A new whitlockite, Ca8.42Na1.16V(PO4)7

Acta Crystallogr C. 2006 Feb;62(Pt 2):i13-5. doi: 10.1107/S0108270105039041. Epub 2006 Jan 21.

Abstract

Single crystals of a new complex phosphate, calcium sodium vanadium phosphate, Ca8.42Na1.16V(PO4)7, have been grown from a melt under an inert atmosphere. The crystal structure has rhombohedral (R3c) symmetry and belongs to the whitlockite structure type. Vanadium(III) ions occupy nearly regular octahedral sites (M5 with 3 point symmetry), which share corners with six PO4 tetrahedra to form isolated units. The calcium ions occupy eight- and nine-coordinated sites. The sodium ions partially occupy one octahedral position and share one nine-coordinated position with a Ca atom.