Ba2NaNb5O15 single crystals doped with Tm3+ and Ho3+:: spectroscopy and energy transfer parameters

Single crystals of Ba2NaNb5O15 (BNN) activated with Ho3+ and Tm3+ have been grown by the 'flux growth' technique. The absorption spectra, the visible emission properties and the decay curves of the excited states have been measured at 10 and 298 K. The room temperature absorption spectra have been analysed by means of the Judd-Ofelt theory and the intensity parameters have been evaluated. The spontaneous transition probabilities, the branching ratios and the radiative lifetimes of the excited states have been calculated and compared with the experimental data in order to estimate the efficiency of the non-radiative processes. The connection between structural and spectroscopic properties has been pointed out in relation to the possible applications of these materials.