Lanthanides doped NaLaMgWO₆ phosphors for anti-counterfeit applications

Luminescence of NaLaMgWO₆ doped with lanthanide activators Tb³⁺, Eu³⁺ and Er³⁺ are reported. These activators exhibit characteristic emission spectra. Either the emission colour or the excitation spectrum distinguishes between these activators. This fact can be exploited for anti-counterfeit applications. Results demonstrating the applications are presented. The luminescent markers using Tb³⁺ and Eu³⁺ phosphors are seen as green and red under illumination by 275 nm and 315 nm light emitting diodes, respectively. Combination of Eu³⁺ and Er³⁺ can also be used. In this case the markers are seen as red and green under illumination by 315 nm and 375 nm light emitting diodes, respectively.