Electron transport in compacted VO₂ nanopowders: Variable-range hopping vs percolation behavior

The electron transport properties of compacted VO₂ nanopowders were studied. While VO₂ usually exhibits a first-order metal-insulator transition (MIT) at ∼340 K, in our compressed nanopowder samples, MIT was significantly broadened due to structural disorder, interparticle barriers, and phase coexistence. Resistivity measurements in the temperature range of 78-682 K initially suggested a Variable Range Hopping transport mechanism, but further analysis indicates that the observed temperature dependence is governed by percolative conduction, further modified by thermally assisted tunneling. Suppression of the expected resistance jump at the MIT is attributed to dynamic intergranular barrier restructuring, residual localized states, and percolative electron transport. These findings highlight the necessity of considering percolation effects when analyzing transport mechanisms in granular VO₂-based systems.