Optical characterization of Pr3+-doped yttria-stabilized zirconia single crystals

The optical absorption and fluorescence of Pr3+ ions in yttria-stabilized zirconia single crystals are investigated. Fluorescence emissions from the D-1(2) level are clearly dominant and low intensity emission lines from the P-3(0) and (1)G(4) states are also observed. Analysis with the Judd-Ofelt theory of the absorption intensities has been made assuming that only similar to 40% of the praseodymium ions contribute to the optical absorption bands. Quantum efficiency values of eta(P-3(0)) similar to 0.2 and eta(D-1(2)) similar to 1 are obtained at room temperature. D-1(2) fluorescence quenching has been observed in heavily-doped samples due to cross relaxation processes among neighboring Pr3+ ions. Analysis using the Inokuti-Hirayama model shows that electric dipole-dipole interactions are mainly responsible for the quenching effect. Pr3+ ions are present in seven and sixfold configurations with a statistical distribution. The energy position of the 4f5d configuration is very different for each center. The fluorescence dynamics is explained by a mechanism involving thermally assisted population of the P-3(1,2) + I-1(6) upper levels and fast relaxation to the D-1(2) level via states of the excited 4f5d configuration.