The effect of thermal cycling on the properties of VO2±Y materials

The article presents the research results of the thermal cycling influence on the ratio of the ultimate composition, chemical state and electrical resistance of VO2 +/- Y system materials. It is established that for all VO2 +/- Y system materials a phase transition semiconductor-metal (PTSM) is observed at temperature of similar to 340 kappa, accompanied by a sharp change in electrical resistance both before and after thermal cycling. Despite the fact that PTMD retained after thermal cycling, the resistivity jump Delta ln(R/R-0) at PTMD for all test materials decreases, the transition temperature becomes more diffused. It is shown that after a series of 30 thermal cycles, the ratio of the surface ultimate composition of all the materials under study changes to a decrease in the oxygen content. Minimal changes in properties as a result of thermal cycling are observed in vanadium dioxide of stoichiometric composition. According to the results of XPS spectra, it was determined that V4+ oxide predominates in the surface layer of VO2 samples, both before and after thermal cycling, and there are also small inclusions of V5+ oxide.