Structurally Restricted Phase Transitions in VO₂(B) and Their Impact on Transport Properties

Despite the relatively simple composition and numerous applications of layered VO₂(B), several issues such as effect of electron correlations and the nature of its metal-insulator transition remain unresolved due to the low irreversible phase transition temperature. We have overcome this challenge by using spark plasma sintering and reporting its reliable electronic transport properties. All our transport, magnetic and thermal data, converge in favor of an interesting multiphase nature of VO₂(B): low temperature phase (insulating and magnetically ordered), an intermediate temperature phase (insulating), and a high temperature phase (presumably metallic with strong electron correlations) coexist. The coexistence domain for these three phases is broad and extends over about 60 K around 235 K. The low temperature phase with spin singlets is always associated with, at least one another phase and becomes dominant below 200 K. The high temperature phase is present over the full temperature range and exists alone above room temperature. We believe that our results will give considerable insight into understand this complex VO₂(B) material and widen up its future applications.