Electrochemical evaluation of oriented vanadium oxide films deposited by reactive rf magnetron sputtering

Thin films of crystalline V2O5 were deposited by reactive rf magnetron sput tering from a metallic vanadium target in argon-oxygen gas mixtures at a su bstrate temperature of 300 degrees C. We found that the orientation directi on of V2O5 films could be controlled by changing the oxygen flow ratio. Cyc licvoltammetry measurements for these films revealed that lithium diffused much faster in the a-axis oriented V2O5 film than the b-axis oriented one. The surface morphology of these samples was also observed, however, there w as not much difference between them, i.e.; lithium ion diffusion was not do minated by the porosity of the film in this case. We also found that chemic al diffusion coefficient of Li along the a-axis of V2O5 was larger than alo ng the b-axis, hence, the lithium ion diffusion in V2O5 film was attributed to the diffusing direction. (C) 1999 Elsevier Science B.V. All rights rese rved.