Synthesis of BaAl12O19:Mn2+ nanophosphors by a reverse microemulsion method and its photoluminescence properties under VUV excitation

BaAl12O19:Mn2+ nanoparticles were successfully synthesized by a reverse microemulsion method. The nanoparticles were characterized by transmission electron microscopy, X-ray diffraction and photoluminescence measurements. The results indicate that BaAl12O19:Mn2+ with spherical morphology can be synthesized at 1200 °C, which is about 300 °C lower than that of solid state reaction with size ranging from 40 to 100 nm. Monitored at 515 nm, the excitation spectra of as-prepared BaAl12O19:x Mn2+ (0.1⩽x⩽0.5) and bulk BaAl12O19:0.1 Mn2+ are similar. The bands at 130 and 156 nm were observed and assigned to the optical absorption of AlO4 and AlO6 groups, respectively. The emission band position of nano-BaAl12O19:0.1 Mn2+ is 6 nm shorter than that of the bulk due to the low symmetry of crystal field near the surface of nano-BaAl12O19:Mn2+. The optimum emission intensity was obtained at x=0.2 of Mn2+ doping. Furthermore, the decay behaviors of nano-sized and bulk BaAl12O19:0.1 Mn2+ have also been discussed.