Flux's influence on the luminescent properties of europium and dysprosium codoped melilite long afterglow phosphor

Abstract

The europium (Eu 2 +) and dysprosium (Dy 3 +) codoped melilite (Sr 2MgSi 2O 7) long afterglow phosphors are synthesized with H 3BO 3 and Li 2CO 3 fluxes, respectively. The XRD analysis demonstrates similar crystal structure and crystal size of the samples. The SEM presents a better crystallization of samples with flux, other than the one without flux. The excitation and emission spectra of the samples are similar but the decay processes of the afterglow are different. The afterglow properties are enhanced by H 3BO 3 while they are suppressed by Li 2CO 3, due to the different concentrations and depths of traps. The sample without flux has a low trap concentration because of the greater surface. Li + ions reduce the concentration of Sr 2 + vacancies and then the trap depth becomes smaller. B 3 + ions break the potential balance in oxygen vacancies then the attraction to trapped electron is enhanced. © 2012 Elsevier B.V.