ELECTRONIC-STRUCTURE OF TI2O3 FROM SINGLE-CRYSTAL THERMOREFLECTANCE SPECTROSCOPY

For the first time studies are made of the polarized thermoreflectance of an oriented Ti2O3 single crystal. The spectra in the photon energy range 1 to 3.5 eV are taken at room and liquid nitrogen temperature. Optical transitions involving the 3d electrons, which play a crucial role in the semiconductor‐to‐metal transition, are studied. The optical transition at 2.9 eV is identified as a transition at a M2 critical point by Kramers‐Kronig analysis of the thermoreflectance spectra. A clear evidence of a plasmon excitation at 1.82 eV in the semiconducting Ti2O3 is reported. The temperature shift of the bands is in agreement with the band‐crossing model of the semiconductor‐to‐metal phase transition. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA