Thermo and mechanoluminescence of Dy3+ activated K2Mg2(SO4)3 phosphor

Abstract

A solid state diffusion method for the preparation of (K 2 :Dy)Mg 2 (SO 4 ) 3 and (K 2 :Dy,P)Mg 2 (SO 4 ) 3 phosphors is reported. Thermoluminescence (TL) and mechanoluminescence (ML) characteristics are studied. TL, shown by the (K 2 :Dy,P)Mg 2 (SO 4 ) 3 phosphor is 60% as intense as the conventional CaSO 4 :Dy phosphor used in the TLD of ionization radiation. It has a linear TL dose response and a negligible fading. These properties of (K 2 :Dy,P)Mg 2 (SO 4 ) 3 should be suitable in dosimetry of ionization radiation using TL technique. ML of (K 2 :Dy)Mg 2 (SO 4 ) 3 shows one peak which has been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radicals (anion radicals produced by γ-irradiation) released from traps during the mechanical pressure applied on the Dy activated K 2 Mg 2 (SO 4 ) 3 phosphor. This ML mechanism is proposed for γ-irradiated sulfate based phosphors. It has been found that the total light output, i.e. ML intensity, increases with concentration of dopant, strain rate and irradiation dose of the phosphor. Mechanoluminescence and ML emission spectra of (K 2 :Dy)Mg 2 (SO 4 ) 3 were recorded for better understanding of the ML process. The TL and ML measurements have also been performed to elucidate the mechanism of ML. Some correlation between ML and TL has also been found.