Systematic investigation of the parameters that influence the luminescence properties of photoluminescent pigments

The formation and quantification of Sr4Al14O25:Eu2+/Dy3+, responsible of specific luminescent properties, was studied as a function of dopants, flux agents, temperature and time of synthesis; this phase was quantified by means of quantitative phase analysis (QPA), using X-Ray Powder Diffraction and Rietveld method. This kind of study gives the possibility to create a specific protocol to find selected parameters that influence the formation of Sr4Al14O25:Eu2+/Dy3+ and their photoluminescence properties. In particular, the present study put in light that a pigment with a slow afterglow decay (high performance by the point of view of its application) must be prepared using low ratios of dopants and varying the synthesis variables in order to maximize the quantity of Sr4Al14O25 as single crystalline phase and to minimize the amorphous phase. Among the synthesis variables, the use of a commercial flux agent based on NH4Cl is very important if compared with that used in the reference synthesis procedure