Fast cross relaxation in lanthanide hexachloroelpasolites: application of the shell model

Luminescence decay curves from the 4G52 state of Sm3+ in the cubic hexachloroelpasolite crystals Cs2 NaSmxY1−xCl6 (x = 0.005 to x = 1) have been measured in the temperature range 10–300 K. Energy transfer from the 4G52 to the 6FJ states occurs at all concentrations studied. At intermediate concentrations the decay curves are strongly non-exponential and are interpreted using a recently developed shell model. Extensions of the model which may provide a better description of the data are briefly discussed.