Abstract
Phase equilibria of the vanadium‐oxygen system have been restudied in the composition range 
in order to establish the conditions required for stable existence of the 
phase. Using this knowledge, it was possible to prepare films of 
exhibiting transition in conductivity between semiconducting and metallic states. Films of 
were first prepared by vapor deposition of vanadyl trichloride at temperatures below 127°C in 1 atm of 
. Reduction of these to 
was accomplished by heating in controlled atmospheres of appropriate partial oxygen pressure at temperatures between 500° and 550°C. The resulting thin film (0.1–1.0µ) exhibited a sharp drop (greater than two orders of magnitude) in resistance at the expected transition temperature, 67 °C.