Room temperature stabilisation of gamma-Bi2VO5.5 and synthesis of the new fluorite phase f-Bi2VO5 by a mechanochemical activation method

Mechanochemical activation followed by annealing at moderate temperatures r esults in the stabilisation at room temperature of the high ionic conductor oxide gamma-Bi2VO5.5 belonging to the Bi-V-V-O-2 system, while in the Bi-V -IV-O-2 system a non-previously reported fluorite-type f-Bi2VO5 phase is is olated. All alpha-, beta- and gamma-Bi2VO5.5 and f-, alpha- and beta-Bi2VO5 , as well as amorphous powders with 2Bi(2)O(3):V2O5 and Bi2O3:VO2 compositi ons, are studied by X-ray powder diffraction at ambient and high temperatur es, thermal analysis and scanning electron microscopy.