A new red-emitting Eu3+ (1-17 mol%)-doped Na3 Mg4 LiSi12 O30 (NMLS) phosphor was prepared using a conventional solid-state reaction method at low temperature. The prepared samples belong to a hexagonal structure with a good match to JCPDS card no. 73-0934. The photoluminescence (PL) emission spectrum showed an intense peak at 612 nm when excited at 393 nm. The variation of electric dipole transition (5 D0 -7 F2 ) emission intensity with increasing Eu3+ ion concentration was investigated. The concentration quenching at 11 mol% is due to the dipole-dipole interaction mechanism in the NMLS host. The optimized NMLS:Eu3+ phosphor shows 2.18 times higher luminescence intensity than the (Y,Gd)BO3 (YGB) commercial phosphor. The NMLS:Eu3+ showed an intense red emission, having Commission Internationale de l'éclairage (CIE) coordinates (0.6280, 0.3691) and colour purity of 99.2%. The resulting phosphor exhibits good thermal stability of 80% at 423 K. The magnified images of fingerprint showed various minute features such as bridges, sweat pores, ridge end, bifurcation, island and core with better visualization under 393 nm excitation. Furthermore, the optimized NMLS:Eu3+ was used for pc-LED, latent fingerprints, and anticounterfeit applications as a promising red phosphor.
Keywords: CIE coordinates; Milarite structure; anticounterfeit; concentration quenching; latent fingerprint; modified solid-state reaction method; thermal stability.
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