Luminescence of rare earth vanadate associates in sulfates

Abstract

In some divalent metal sulfates (CaSO4, PbSO4) the introduction of trivalent rare earth ions on the metal sites and pentavalent vanadium on the sulfur sites results in the formation of associates V03-4-RE3+. Energy transfer from the vanadate group to trivalent rare earth ions can be studied in these systems. It is shown that the transfer rate is temperature independent, but depends strongly on the choice of the host. In CaSO4 the transfer rate in the associate is estimated to be ≈ 108 s-1, and in PbSO4 t˜104 s-1. The low transfer rate in PbSO4:RE, V is ascribed to the influence of the Pb2+ ions on the charge distribution in the vanadate group.