Thermal Expansion of Tetragonal Phase of VO2

Abstract

Accurate lattice parameters of the tetragonal phase of VO ₂ have been determined as a function of temperature by X-ray powder method in the temperature range 78°C to 415°C. Both the lattice parameters are found to increase with increasing temperature, the relative increase in the ` c ' parameter being greater than that in the ` a ' parameter. Using the data the coefficients of thermal expansion, α _{|| |} and α _⊥ , have been calculated by a graphical method. Temperature dependence of the coefficients are represented by the following equations: