Hybrid hexagonal perovskite Ba3WVO8.5 phosphor: 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 Ba 3 WVO 8.5 , a hybrid hexagonal perovskite. Ba 3 WVO 8.5 acts 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, WO 6 and VO 6 , in the lattices that contribute to the self-activated luminescence. The photoluminescence (PL) and temperature-dependent spectra confirm the energy transfer process from WO 6 to VO 6 centers. The cation substitutions in Ba 3 WVO 8.5 can exert obvious effect on the luminescence efficiency. Especially, the substitution of Ba 2+ by Sr 2+ +Ca 2+ significantly enhances its self-activated luminescence. The maximum quantum efficiency (QE) in Ba 2.7 Sr 0.15 Ca 0.15 WVO 8.5 can reach up to 34 %. Moreover, Ba 3 WVO 8.5 exhibits scintillation characteristics under X-ray irradiation. Its emission efficiency is still significantly lower than that of the commercial Bi 4 Ge 3 O 12 scintillator, but Ba 3 WVO 8.5 shows 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.
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