Photoluminescence investigation of Tm3+/ Dy3+ co-doped LiNa5(PO4)2 phosphors for color tunable LED applications

One of the main areas of research at the present time is the production of luminous materials. Particularly, materials based on inorganic phosphor have been widely used for many different kinds of applications, such as white light emitting diodes (WLEDs), radiation dosimetry, field emission displays (FEDs), cathode ray tubes (CRTs), and lamp industries. In this research, we successfully synthesized single-host LiNa₅(PO₄)₂: Tm³⁺/Dy³⁺ by using the solid-state reaction method to achieve white light emission. The luminescence properties of the synthesized samples were analyzed under UV light. XRD analysis confirmed the phase purity of LiNa₅(PO₄)₂. SEM images showed that the phosphor materials tend to form agglomerates. Photoluminescence (PL) measurements of LiNa₅(PO₄)₂:Dy³⁺doped phosphors demonstrated efficient excitation at 349 nm, with prominent emission bands at 487 nm (blue) and 576 nm (yellow). For LiNa₅(PO₄)₂: Tm³⁺ doped phosphors, strong orange emissions were observed at 458 nm corresponding to the ¹D₂→³H₄ transitions in Tm³⁺ ions. Co-doping with these rare earths resulted in strong blue and yellow emissions. The color qualities of the luminous prepared samples were calculated using the CIE color coordinates. Therefore, these findings result suggest that Tm³⁺/Dy³⁺ co-doped LiNa₅(PO₄)₂ phosphors, when excited by UV LEDs could be suitable for producing white light emitting diodes and display devices.