Spectroscopy and energy transfer in Tb3+/Sm3+ co-doped lead borate glasses

In this work, luminescence properties of Tb3+/Sm3+ co-doped lead borate glasses are examined in details. Luminescence spectra of rare earths were measured under different excitation wavelengths. Characteristic luminescence bands corresponding to electronic transitions of terbium and samarium ions were detected under direct excitation of Tb3+. The energy transfer from Tb3+ to Sm3+ ions in lead borate glass occurs through a nonradiative process with an efficiency from 0.6% to 16%, depending on samarium concentration. Luminescence decay curves for the 4G5/2 state of Sm3+ ions in lead borate glasses were fitted using the Inokuti-Hirayama model. The concentration-dependent luminescence quenching was explained by the non-radiative energy transfer process between the Sm3+ ions through the cross-relaxation mechanism. The CIE chromaticity coordinates and correlated color temperatures for Tb3+/Sm3+ co-doped lead borate glasses are also presented and discussed.