Tunable emission, energy transfer and cation substitution in the Li2Sr2Al(PO4)3:Dy3+, Eu3+, Na+ phosphor for WLEDs application

Abstract

The current investigation deals with the synthesis and characterization of the singly, double and triple ions (Dy3+, Eu3+, Na+) co-doped Li2Sr2Al(PO4)3 phosphors. The entire series of suggested phosphors has been successfully synthesized using a straightforward combustion method and their XRD and Rietveld refinement pattern confirms the phase formation and successful synthesis of material. The morphological behaviour, elemental composition, vibrational features, thermal stability and luminescence properties were carried out by SEM-EDAX analysis, FT-IR, TG-DTA and photoluminescence techniques. The single Dy3+ doped Li2Sr2Al(PO4)3 phosphors exhibits blue and yellow emission band around at 482 nm and 572 nm monitored at 350 nm, 365 nm, 388 nm excitation. While, Eu3+ doped Li2Sr2Al(PO4)3 phosphors exhibits orange and red emission band around at 592 nm and 615 nm under 395 nm and 466 nm excitation. According to Froster and Dexter theory, the PL excitation spectrum Dy3+ doped Li2Sr2Al(PO4)3 phosphor and Eu3+ doped Li2Sr2Al(PO4)3 phosphor are overlapped to each other. Consequently, an investigation was conducted to study the transfer of energy between Dy3+ and Eu3+. In addition, to improvement in emission intensity and color tunning host cation (Li+) replaced with another cation (Na+) and their impact was studied. The photometric characterization like CRI Chromaticity coordinate, CRI and CCT values are also estimated using color calculator. The host cation substitution revealed that performance of Dy3+/Eu3+ doped Li2Sr2Al(PO4)3 phosphors were improved with doping of Na+ ions. The overall study and their estimated results suggested that Dy3+, Eu3+, Na+ ions doped Li2Sr2Al(PO4)3 phosphors have huge ability for WLEDs application and their future investigation.