TEMPERATURE DEPENDENCES OF THE OPTICAL PROPERTIES AND ELECTRONIC STRUCTURE OF VANADIUM DIOXIDE.

Measurements are presented of the spectra of the reflectivity R, transmission t, absorption alpha , thermoreflectance thermotransmission, and electroreflectance at photon energies from 0. 2 to 2. 5 eV in the temperature range 85-380 degree K. It is shown that increasing temperature within the low-temperature phase range leads to changes in the spectrum of alpha which are qualitatively similar to those occurring at the phase transition and which correspond to an increase in the width of the occupied and empty 3d bands nearest to E//f, to a decrease in the energy gap between the maxima of their densities of states, and to an increase in the probability of transitions between them.