Nonradiative energy transfer and ion-ion interactions in terbium-praseodymium coactivated borate glass

A study of energy transfer between Tb³⁺ and Pr³⁺ in borate glass is being presented. From our measurement of fluorescence emission and decay times of donor (Tb³⁺), in the presence of different concentrations of acceptor (Pr³⁺), the energy transfer probability (P_da) and transfer efficiency (η_T) have been calculated. Analyzing the data it is observed that the non-radiative energy transfer in our borate glass system occurs by dipole-dipole interactions, contrary to the observations made by Nakazawa and Shionoya (dipole-quadrupole interaction) in phosphate glass. A linear dependence of P_da versus C at low acceptor concentration suggests the migration of excitation energy among donor ions before the energy is finally transferred to the acceptor ion. At high acceptor concentrations a plot of P_davs (C₀ + C)²; where C₀ is donor concentration and C is the acceptor concentration, presents a linear dependence suggesting thereby that one donor interacts with two neighbouring acceptors consistent with Fong-Diestler mechanisms of dipole-dipole energy transfer interactions.