Phase transitions in V₂O₅ in a high resolution electron microscope

This paper presents data on phase transitions in vanadium pentoxide induced by electron beam irradiation in a high resolution electron microscope. The results show that the concentration gradient resulting from loss of oxygen from the surface drives a number of phase transitions. Two intermediate phases with orthorhombic structures, V₄O₉ and a modification of V₆O₁₃, were observed. The final product was a vanadium monoxide with a rock-salt type structure. The end product and the intermediate phases have a well defined orientational relationship with the initial V₂O₅ phase, when the incident electron beam is along [001] or [110] of the V₂O₅. The average grain size of the final phase was proportional to the inverse square root of the flux of electrons, indicating diffusion-controlled nucleation.