A novel highly thermal-stable red-emitting CaGdSbWO8:Eu3+ phosphor with scheelite structure for high CRI w-LEDs,security ink, and latent fingerprint

Abstract

Recently, rare-earth doped phosphors have been newly developed and applied in hot issues such as phosphor-converted light-emitting diodes (pc-LEDs), anti-counterfeiting, and fingerprint visualization. Herein, an Eu 3+ -activated CaGdSbWO 8 (CGSW) red phosphor was synthesized by a high-temperature solid-state reaction. The phosphors can exhibit narrow red-light emission at 614 nm due to the electric dipole transition 5 D 0 → 7 F 2 of Eu 3+ . Impressively, this phosphor has excellent thermal stability, its emission intensity of optimum sample doped with 0.30 Eu 3+ remained 90.61% at 420 K and thermal quenching temperature exceeds 480 K. The Commission International del’Eclairage (CIE) chromaticity coordinates of CGSW:0.30Eu 3+ are (0.662, 0.338) with a high color purity (98.5%). The fabricated white light diode (w-LED) has a high color rendering index (91.4) and a low correlated color temperature (4986 K) with CIE coordinates (0.343, 0.327). Further experimental results showed that the prepared security ink can be applied to anti-counterfeit labels and information encryption. The latent fingerprint developed by CGSW:0.30Eu 3+ phosphor present the excellent selectivity and contrast. The level 1–3 structural characteristics of latent fingerprints could be well identified under ultraviolet irradiation. Therefore, the Eu 3+ -activated CGSW red-emitting phosphor has broad application prospects due to its excellent luminescence properties. • Novel CaGdSbWO 8 :Eu 3+ phosphors have been synthesized via high-temperature solid-state method. • The CaGdSbWO 8 :Eu 3+ phosphors with scheelite structure have good thermal stability ( T 0.5 >480 K). • The w-LED fabricated by the phosphor exhibits a high CRI value of 91.4 and a good CCT of 4986 K. • The applications in security ink and latent fingerprint of CaGdSbWO 8 :Eu 3+ phosphors are investigated in details.