Hybrid hexagonal perovskite Ba₃WVO_8.5phosphor: self-activated luminescence based on two intrinsic centers

Transition metal perovskite oxide is one of the most important functional materials for applications in light energy conversion due to the distinctive structures and characteristics. This work reports self-activated luminescence of Ba₃WVO_8.5, a hybrid hexagonal perovskite. Ba₃WVO_8.5acts as an indirect allowed transition, with a band gap energy of 3.2 eV. At 300 K, it exhibits a broad self-activated luminescence band peaking at 527 nm, with a decay lifetime of 0.09 μs. There are two distinct intrinsic centers, WO₆and VO₆, in the lattices that contribute to the self-activated luminescence. The photoluminescence (PL) and temperature-dependent spectra confirm the energy transfer process from WO₆to VO₆centers. The cation substitutions in Ba₃WVO_8.5can exert obvious effect on the luminescence efficiency. Especially, the substitution of Ba²⁺by Sr²⁺+Ca²⁺significantly enhances its self-activated luminescence. The maximum quantum efficiency (QE) in Ba_2.7Sr_0.15Ca_0.15WVO_8.5can reach up to 34 %. Moreover, Ba₃WVO_8.5exhibits scintillation characteristics under X-ray irradiation. Its emission efficiency is still significantly lower than that of the commercial Bi₄Ge₃O₁₂scintillator, but Ba₃WVO_8.5shows advantages in QE under UV excitation and in fast decay lifetime. The experimental results may play a valuable role in the development of new luminescent materials and further understanding of the hybrid hexagonal perovskite oxides.