Luminescence and decay kinetics of Pb2+ center in LiCaAlF6 single crystal host

The Pb-doped LiCaAlF6 single crystals were grown using the micro-pulling-down method. The temperature dependences of photoluminescence characteristics were studied to reveal the kinetic processes in the excited state of Pb2+ luminescence center. A simple three-level phenomenological model applied to the decay time temperature dependences shows that energy separation between the metastable 3P0 and the radiative 3P1 states of Pb2+ center is relatively high, about 180 meV (∼1470 cm−1). Induced absorption spectrum after UV illumination at 500 K points to slight ionization of the Pb2+ excited state and creation of the color F-center with an absorption peak located around 260 nm.