Structure and luminescence of Ba3Eu2(BO3)4: F phosphors for WLEDs and FIR optical temperature sensor

Abstract

Eu3+-activated luminous materials play important roles in WLEDs and optical temperature sensors, etc. While most Eu3+-activated phosphors have suffered from notable problems including low thermal quenching (TQ) temperature and quantum efficiency (QE). Here, we report a serial of Ba3Eu2(BO3)4: xF (BEB: xF) (x = 0–0.7) phosphors covering high QE (97.3%) and excellent thermal stability (83.6%@423 K). Structural and spectral analysis indicate that Eu3+ in the 8d lattice site dominantly attributes to the red emission. F- ions substitution induces more distorted inversion asymmetry for Eu3+ and results in stronger luminescence. Comparing serials of reported red phosphors under ∼393 nm excitation, these newly developed red phosphors present outstanding QE. Using the new excellent BEB: xF phosphors, two representative WLEDs have been fabricated with a satisfactory color-rendering index and luminous efficacy, demonstrating their potential performance for WLEDs. Meanwhile, a highly sensitive non-contacted optical thermometer has also been designed with the maximum relative sensor sensitivities of about 2.23% and 2.42% K−1 for BEB: xF (x = 0, 0.5) phosphors, respectively. This kind of single-activator doped phosphors provides a new and effective way for realizing dual-functional applications. In addition, the strategy of anion substitution can be adopted to develop optimal phosphors.