Mechanochemically-assisted Synthesis of LaVO₄ and LaVO₃

Abstract

Mechanochemical synthesis and solvothermal crystallization of LaVO₄ and LaVO₃ have been studied. Amorphous LaVO₄ powders were mechanochemically synthesized by the mixing-grinding operation of La₂O₃ and V₂O₅ in Acetone containing water as the grinding liquid. The amorphous ground products were crystallized to monoclinic-LaVO₄ by the solvothermal post treatment at 120℃ for 12 h. The BET surface area of the LaVO₄ powder after the calcination at 600℃ was 9.6～26.3 m² g^-1. The reflux treatment was also applicable to the crystallization. For the synthesis of LaVO₃, the mechanochemical reduction of V₂O₅ in organic vapors was applicable. The ground product prepared by mixing-grinding of La₂O₃ and V₂O₅ in acetone vapor was crystallized to the single phase tetragonal-LaVO₃ after the calcination at 800℃ in Ar, although the mechanochemical/solvothermal products contained a certain amount of LaVO₄ after the calcination at the same condition.