Energy transfer from the5D1state of Cs2NaY1-xEuxCl6and Cs2NaEuCl6

Abstract

The luminescence decay curves from the ⁵D₁ state of the cubic hexachloroelpasolite crystals Cs₂NaY_1-xEu_xCl₆ (x=0.01, 0.05, 0.10, 1) have been measured over the temperature range 12-293 K. For x=0.01, cross-relaxation processes involving odd parity phonons occur at 293 K but are quenched at 80 K. For x=0.05 and 0.10 both temperature-dependent energy migration among the donors and cross-relaxation occur. For the pure material energy transfer from the donors to the nearest-neighbour acceptors becomes dominant and the emission is strongly quenched. The multipole nature of the coupling mechanisms and the identity of the states involved is discussed.