Theoretical and Experimental Investigation of the Tb<sup>3+</sup> → Eu<sup>3+</sup> Energy Transfer Mechanisms in Cubic A<sub>3</sub>Tb<sub>0.90</sub>Eu<sub>0.10</sub>(PO<sub>4</sub>)<sub>3</sub> (A = Sr, Ba) Materials
Albano N. Carneiro Neto, Renaldo T. Moura, Andrii Shyichuk, Veronica Paterlini, Fabio Piccinelli, Marco Bettinelli, Oscar L. Malta
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.