Doped Yttrium Aluminum Garnet Crystal Research Articles

Infrared to blue up-conversion in Pr3+ doped YAG and LiYF4 crystals

Spectroscopic studies of the up-conversion excitation of the blue3P0 emission using two near-infrared photons in Pr3+ doped yttrium aluminum garnet and LiYF4 crystals are reported. The excitation spectra and decay time measurements indicate the sequential absorption of two photons with the nonresonant first step. Two-photon excitation spectra revealed a structure not seen in one-photon measurements, allowing identification of several1I6 Stark levels.

The Temperature Dependence of Rare‐Earth Activated Garnet Phosphors: I . Intensity and Lifetime Measurements on Undoped and Ce‐Doped

The temperature dependence of cathodoluminescence intensity and decay time in the range 10°–480°K is reported for both nominally pure and Ce3+‐doped yttrium aluminum garnet (YAG) crystals. Luminescence from characteristic lattice defect levels and from the 2D excited state of the Ce3+ impurity have both been investigated. Three lattice defect levels have been detected. Recombination is dominated by the shallowest centers at low temperatures but, at higher temperatures, thermalization effects reduce the net capture rates at the competitive defect centers. As a result of thermalization in the doped crystal the efficiency of energy transfer to Ce3+ is increased, but only at the expense of introducing a long afterglow into the Ce3+ decay near room temperature. The temperature‐dependent interactions between different centers in the lattice are adequately described by a simple kinetic model. Each center is characterized by three rate processes and by a thermalization activation energy which is derived from the decay time data. The experimental results are in good agreement with preliminary studies already reported by the authors.