Synthesis and luminescence characterization of aqueous stable Sr3MgSi2O8: Eu2+, Dy3+ long afterglow nanophosphor for low light illumination

Abstract

Sunlight rechargeable and blue light-emitting (∼460 ​nm) silicate based Sr3MgSi2O8:Eu2+, Dy3+ afterglow phosphor was synthesised via the facile co-precipitation method with an afterglow of >30 ​min. Detailed investigation on structural, morphological, thermal and optical characteristics of the as-prepared samples were done. XRD confirms the existence of Sr3MgSi2O8 phase along with an additional phase of β-Sr2SiO4 with crystallite size of ∼24 ​nm. No enthalpy change was observed in the sample beyond a temperature of 600 ​°C temperature as studied from Differential Scanning Calorimetry (DSC).Remarkably, excitation spectra of Sr3MgSi2O8:Eu2+, Dy3+ was found overlap with UV-B and UV -A of solar spectrum received on the earth surface. Thus, as synthesised phosphor can be readily excitable by sunlight. Interestingly, emission intensity of the sample was found to persists more than 80% of its initial value even at high temperature of 100 ​°C. Commission Internationale de l'éclairage (CIE) color coordinates of Sr3MgSi2O8:Eu2+, Dy3+ were calculated to be (0.15, 0.05) and were found to be close to standard National Television Standard Committee (NTSC) coordinates for blue light with a color purity of 95%. Real time demonstration of the aqueous stability of the Long Afterglow Phosphor (LAP) was also studied and the solution was found to be stable on a time scale of two months. Thus, as prepared Sr3MgSi2O8:Eu2+, Dy3+ are a potential candidate for waterborne coatings, water-based paints and security inks.