Structure and optical absorption of LiyV2O5 thin films

Abstract
Thin films of LiyV2O5 (0<y4. X‐ray diffractometry showed an orthorhombic structure that varied from nanocrystalline (nX ) for unheated substrates to polycrystalline (pX ) for substrates at 180 °C. Optical absorption was measured at 0.3<λp‐X LiyV2O5 and appeared blue‐shifted in proportion with y for nX Liy V2O5. At λ>0.5 μm there are absorption peaks associated with V4+ ions both for pX and nX materials, and a broad absorption feature for pX Liy V2O5 that is tentatively ascribed to electron hopping in the crystallographic b direction. The absorption goes up for increased y, as expected from the higher V4+ density.