Preparation and optical characterization of Yb3Sb5O12:: Discussion of its suitability for laser operation

Pure and polycrystalline samples of Yb3Sb5O12 were prepared under vacuum by solid-state reaction. In this cubic matrix, space group I (4) over bar 3m (No. 217), Z = 4, Yb3+ occupies a single crystallographic site with point symmetry S-4. The confident determination of the Yb3+ energy levels was carried out through the analysis of 9 K optical absorption (OA) and photoluminescence (PL) spectra, and 300 K Raman measurements, assisted by models and procedures providing proper estimations of crystal-field (CF) interactions in this host. The parametrization of free-ion and CF effects for Er3+ in Er3Sb5O12 has been revised and then used as reference in the simulation of Yb3+ CF energy levels. The correctness of the energy level sequence of Yb3+ in Yb3Sb5O12, which is characterized by a large splitting for the F-2(7/2) ground state, 933 cm(-1), and the composition of the associated wave functions were tested through the successful reproduction of the thermal evolution of the paramagnetic molar susceptibility chi(m), of Yb3Sb5O12. Some parameters of interest accounting for application perspectives as a laser material have been evaluated and compared with those corresponding to other stoichiometric and Yb-doped confirmed laser materials.