Synthesis and Magnetic Properties of beta-KVOF3

Abstract

The potassium vanadium oxide-fluoride phase -KVOF3 was prepared by in-situ reduction with hydrothermal methods and characterized by single-crystal X-ray diffraction and magnetic susceptibility measurements. The compound is orthorhombic [space group Pnma, a = 7.1596(2) angstrom, b = 7.5392(2) angstrom, c = 13.0506(4) angstrom, Z = 8]. The material is structurally similar and isoformulaic to d(1) materials of formulae AVOF(3) (A(+) = alkali metal, ammonium, or organic cation). Magnetic susceptibility data were successfully fit with a Heisenberg chain model. In-situ reduction of V5+ to V4+ during the hydrothermal reaction conditions was observed in the presence of Br- anions. The role of bromide ions in this reduction is explained and employed to reduce a d(0) vanadium species to obtain a material with magnetic behavior.