A terbium activated multicolour photoluminescent phosphor for luminescent anticounterfeiting

Abstract The multicolor photoluminescence (PL) of a Tb3+ singly activated NaYGeO4 phosphor is presented by solid state method. For the first time, it is reported that the PL color of Tb3+ in NaYGeO4 phosphor can be tuned from green to blue and, finally, to red by controlling the Tb3+ content. The optimal tricolor phosphors are NaYGeO4:0.01mol% Tb3+ (red), NaYGeO4:0.5mol% Tb3+ (blue) and NaYGeO4:5mol% Tb3+ (green), respectively. The PL properties of the NaYGeO4: Tb3+ phosphor were studied in details. The results reveal that the PL color modulations of the NaYGeO4:Tb3+ phosphor are essentially due to the cross-relaxation effect of Tb3+, and a possible mechanism on the cross-relaxation is proposed. According to these unique features, a multicolor PL image is fabricated based on the NaYGeO4: Tb3+ phosphor for potential applications in luminescent anticounterfeiting.