Modeling optical transitions of Er~(3+)(4f~(11)) in C_2 and C_(3i) sites in polycrystalline Y_2O_3

摘要

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 ~(2S+1)L_J multiplet manifolds of Er~(3+)(4f~(11)) in both the C_2 and C_(3i) sites of Y_2O_3 are analyzed in terms of established models. The inversion symmetry of C_(3i) sites limits the observed electronic transitions to magnetic dipole transitions between the ~4I_(13/2) and ~4I_(15/2) manifolds. There is no spectroscopic evidence for transitions involving other multiplet manifolds of Er~(3+) ions in C_(3i) sites. For Er~(3+) ions in C_2 sites, forced electric dipole transitions are allowed between the J + 1/2 Stark levels associated with each manifold. With few exceptions, the crystal-field splitting and the intensities of the transitions between Stark levels are comparable between the nanocrystalline, polycrystalline, and the flame fusion grown crystals of cubic yttrium oxide containing trivalent erbium.