Theoretical and Experimental Investigation of the Tb³⁺ → Eu³⁺ Energy Transfer Mechanisms in Cubic A₃Tb_0.90Eu_0.10(PO₄)₃ (A = Sr, Ba) Materials

Abstract

In this study the optical spectroscopy, the excited state dynamics, and in particular the Tb3+ → Eu3+ energy transfer, have been investigated in detail both from the theoretical and experimental point of view in eulytite double phosphate hosts A3Tb(PO4)3 (A = Sr, Ba) doped with Eu3+. It has been found that the energy transfer is strongly assisted by fast migration in the donor Tb3+ subset. Moreover, the transfer rates and efficiencies depend significantly on the nature of the divalent elements present in the structure and hence on the distances between Tb3+-Eu3+ nearest neighbors. It is shown that the competition between quadrupole–quadrupole and exchange interaction is crucial in accounting for the transfer rates.