Magnéli phase vanadium oxide thin films produced by stepwise oxidation of vanadium metal foil

We produced Magnéli phase vanadium oxides with a thickness of approximately 1.0 μm on the surface of vanadium metal foil via a stepwise oxidation process consisting of annealing at 723 K in air and a subsequent heat treatment at 773 K under a low oxygen partial pressure of PO2 = 1.0 × 10−10 atm. The diffuse reflectance of samples with a Magnéli phase vanadium oxide was less than 20%, indicating the absorption of visible and near-infrared lights. Magnéli phase vanadium oxides with the desired vanadium-to-oxygen atomic ratio could be produced by controlling the heat-treatment conditions in our oxidation process.