Electrical Properties of β-LixV2O5 Thin Layers Prepared by the Sol—Gel Process

The electrical properties of a highly oriented thin layer of lithium vanadium beta bronze, β-Li_xV₂O₅, were investigated through dc and ac conductivity measurements. The ionic transference number was determined by a simplified polarization method employing ion-blocking electrodes. The electronic conductivity was 10 ^–3to 10^–2 S cm^–1 in air or N₂ at 300–400°C, which was lower than that of a randomly oriented sintered specimen. The ionic conductivity was l0^–2–10^–1s cm^–1 at 350°C, resulting in a high ion transference number of 0.8–0.9; it was higher than that reported for a bulk specimen. The lower electronic conductivity and higher ionic conductivity were assumed to be due to (1) the oriented microstructure, i.e., alignment of the b -axis along the substrate direction which enhanced Li⁺ conduction through tunnels along the b -axis, and (2) an open crystallo-graphic structure, which promoted ionic motion in an open channel between adjacent ( a-c ) places and suppressed the electron hopping process in the b -axis direction.