The optical properties of Er 3+ in polycrystalline (ceramic), and nanocrystalline forms of
cubic (bixbyite) yttrium oxide are modeled based on the absorption spectra obtained
between 400 and 1700 nm and the fluorescence spectra observed between 1500 and 1670
nm. Both spectra were obtained at 8 K. The observed crystal-field splitting and the measured
intensities of transitions between Stark levels of the L 2 S+ 1 J multiplet manifolds of Er 3+(4 f
11) in both the C 2 and C 3 i sites of Y 2 O 3 are analyzed in terms of established models …