Photoluminescence investigation of novel red emitting NaLa(1-x)MgTeO6: xSm3+ phosphor with high color purity for n-UV based warm WLEDS and anti-counterfeiting applications

Recently, red phosphors are extensively developed to find applications in phosphor converted white LEDs (pc-WLEDs) and anti-counterfeiting. In this work, samarium doped sodium lanthanum magnesium tellurate (NaLaMgTeO6:Sm3+) red emitting phosphors have been synthesized for the first time via solid state reaction method. Rietveld refinement of XRD pattern reveals monoclinic crystal structure of NaLaMgTeO6. Under 404 nm (6H5/2 → 4F7/2) n-UV excitation, NLMT:Sm3+ phosphor shows red emission at 643 nm (4G5/2 → 6H9/2) with color purity 100% and the obtained CCT value corresponds to warm light source. Temperature-dependent PL analysis of NLMT:Sm3+ exhibits good thermal stability. The anti-counterfeiting security ink was developed using optimized phosphor and the information was encrypted on different surfaces using the prepared security ink. The encrypted data was decoded only by n-UV light. The aforementioned results revealed that NLMT:Sm3+ is a highly effective phosphor as a red component for pc-WLEDs and luminescent dye for anti-counterfeiting applications.