Luminescence enhancement of Na3Ca2TaO6:Eu3+red phosphor and its applications in warm white LEDs and latent fingerprint detection

A suite of Eu 3+ -doped Na 3 Ca 2 TaO 6 (NCTO) red-emitting phosphors was prepared via a high-temperature solid-state reaction. Under 464 nm blue light excitation, these samples showed a prominent red emission peak at approximately 610 nm corresponding to the 5 D 0 → 7 F 2 transition. Optimal luminescence was achieved at a doping concentration of 25 mol%, where concentration quenching occurred mainly due to dipole–dipole interactions. Interestingly, this material displayed abnormal thermally enhanced luminescence, its emission intensity at 398 K was 32% higher than at room temperature. The activation energy for thermal quenching was determined to be 0.55 eV, and the internal quantum efficiency reached 60.86%. A WLED fabricated with the optimized NCTO:0.25Eu 3+ phosphor and a 395 nm LED chip exhibited a color rendering index of 91.4 and a correlated color temperature of 4687 K. Furthermore, this phosphor enabled clear visualization of tertiary-level details in latent fingerprint imaging and also showed promise for optical anti-counterfeiting applications.