Synthesis and Optical Properties of BaFBr and BaFBr:Eu2+ Nanoparticles

BaFBr nanoparticles were synthesized by cetyltrimethylammonium bromide (CTAB)/2-octanol/water microemusion systems. X-ray diffraction (XRD) analysis shows that depending on the molar starting ratio of NH4F to NH4Br, stoichiometric BaFBr with or without a BaF2 phase is obtained. As the ratio of NH4F to NH4Br reduced from 1.0:1.0 to 1.0:4.0, the product formed pure BaFBr. Calculations using the Debye-Scherrer equation from line widths of the XRD and transmission electron microscopy (TEM) images show particle sizes of less than 100 nm. Europium-doped BaFBr nanoparticles (with molar ratio of Ba:Eu equal to 1:0.005) were also synthesized according to the conditions of the pure BaFBr product. Photoluminescence (PL) and photostimulated luminescence (PSL) signals of europium-doped BaFBr, however, were not measurable. Thermal processing for 20 min at 800 degrees C in a reducing atmosphere leads to the observation of Eu2+ fluorescence and PSL.