Optical spectroscopy and crystal field calculation of Tb3+ doped in YAl3(BO3)4 single crystal

Single crystals of YAl3(BO3)4 doped with 2.8% Tb3+ were grown by spontaneous nucleation from K2Mo3O10 and B2O3 flux. The electronic structure of Tb3+ ions doped in YAl3(BO3)4 crystals are investigated using photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. Emission spectra at room and low temperature were measured and were identified from the excited 5D4 to the ground state multiplets 7F0,1,2,3,4,5,6. The main emission detected around 540 nm corresponds to the 5D4-7F5 transition. Calorimetric parameters of the Tb3+ ions green emission in YAB are calculated (x=0.30, y=0.67). The corresponding decay time around 2.74 ms is fitted with a simple exponential curve. The observed transitions are assigned and analyzed on the basis of group theory assuming that Tb3+ ion occupies a D3 symmetry site. The experimental Stark energy levels of the Tb3+ manifolds are established. The crystal field parameters were determined. A best fit between theoretical and experimental energy levels is obtained. The general trend of the crystal field parameters of rare earth ions in YAB host is confirmed. The calculated Nv crystal field strength parameters present a linear variation with 4f electrons number over the rare earth series.