The effect of the surface coating of a strontium mono-aluminate europium dysprosium-based (SrAl2O4:Eu2+,Dy3+) phosphor by polyethylene (PE), polystyrene (PS) and their dual system on the photoluminescence properties of the pigment

Abstract

SrAl₂O₄:Eu²⁺,Dy³⁺ as a known strontium mono-aluminate europium dysprosium-based phosphor is widely used in paints and coating formulations as a photoluminescence pigment. It has two major drawbacks: improper dispersion in organic-based paints and weak water and moisture resistance. To address the above-mentioned drawbacks, the surface coating of phosphors with polyethylene and polystyrene individually and in combination using a solution technique was performed. The FT-IR spectra showed that the used polymers were coated on the phosphor properly. Also, the EDS spectra showed the presence of elemental carbon for the treated phosphors with different amounts. No regular trend was observed for element ratios when the polyethylene content in the coating layer was reduced from 100 to 0%. Based on the XRD patterns, the crystalline structure of the coated phosphors was not affected by the polymeric coated layer. In the SEM micrographs, the sharp and rough edges of the uncoated phosphor changed to a smooth and soft state for the coated phosphors. The brightness of most of the coated phosphors was independent of time and did not change over a period of 5 minutes after UV irradiation. This property makes the polymeric coated phosphors suitable as photoluminescence pigments in all kinds of paints and coatings.