Abstract
The stoichiometry-dependent optical properties of bulk samples of have been determined for four samples in the range . Reflectance and absorptance data taken in the range 0.1-30 eV have been Kramers-Kronig analyzed to obtain the dielectric function and related functions. Interband absorption begins at 0.1 eV or less. The observed interband transitions are interpreted on the basis of existing energy-band calculations. Comparison of optical structure with joint-density-of-states calculations shows that the rigid-band model cannot be applied strictly to explain the -dependent structure, especially in the 5-10 eV region. The electron-energy-loss functions exhibit two peaks, one near the free-electron plasmon energy and one near 10 eV, both peaks shifting to higher energy as increases.
- Received 30 October 1979
DOI:https://doi.org/10.1103/PhysRevB.22.3991
©1980 American Physical Society