Orange-red-emitting BaSrGd4O8:Sm3+phosphors with high thermal stability for applications in w-LEDs and latent fingerprints

Orange-red BaSrGd4O8:Sm3+ phosphors were obtained by a high-temperature solid-phase reaction. During this study, lattice environment, phase purity, element distribution, Photoluminescence (PL) spectra, thermal stability, and color purity of BaSrGd4O8:Sm3+ was systematically explored. The phosphors present a strong excitation with the charge transfer band (CTB) of O2- and Sm3+at 253 nm. Under 253 nm excitation, the BaSrGd4O8:Sm3+ phosphor shows characteristic peaks at 566, 605, 651, and 708 nm, which can be consistent with the 5G5/2 -> 6HJ (J = 5, 7, 9, 11). And 605 nm is the most vigorous emission. The optimal doping concentration of BaSrGd4O8: Sm3+ is x = 1 mol%. Notably, as the temperature rises to 420 K, the BaSrGd4O8:Sm3+ still has outstanding thermal stability, reaching 95.38% of the initial luminescence intensity. Internal quantum efficiency (IQE) is tested as 64.83%. After calculation, the color purity of all phosphors reaches 96.5% or above. In addition, the wLED (white light emitting diode) and single-colored LED were successfully prepared with 405 nm chips. The CIE (Commission International de L' Eclairage) coordinate of the packaged w-LED is (0.348, 0.335), which has the high color rendering index (CRI) of 90. Besides, the latent fingerprints (LFPs) visualized by BaSrGd4O8:Sm3+ phosphor can be clearly displayed. These experimental results exhibit the BaSrGd4O8:Sm3+ orange-red phosphors have promising application prospects in lighting devices and LFPs.