Study On The Process Of The Preparation Of High Purity BaF₂ And BaF₂ Nanoparticles From Microemulsion Systems

BaF2 has special photoluminescence characteristics as new scintillating crystal and good optical matrix material.The high purity BaF2 was prepared with ammonium fluoride and barium chloride as raw material in aqueous solution. It was studied on the changes of the structural parameters of W/O microemulsion systems CTAB/alcohol/n-heptane /water with the increasing of Wo or carboatomic numbers of straight chain alcohol. BaF2 and BaF2:Ce3+nanoparticles were prepared from W/O microemulsion systems CTAB/n-butanol/n-heptane/water.A new technology was the preparation of the high purity BaF2 from ammonium fluoride and barium chloride. The optimum operational conditions for the preparation of BaF2 were reaction temperature 25℃, reaction time 60min, initial mass concentration of barium chloride 10%, n(NH4F):n(BaCl2)=2.2, the ratio of washing amount to filter cake amount=10:1, washed 3 times. The purity of BaF2 was up to 99%. The procedure has short flow route and good economic benefits.Dilution was used to measure and calculate the structural parameters of W/O microemulsion systems CTAB/alcohol/n-heptane/water at different moisture contents and different alcohol. In the W/O microemulsion systems CTAB/alcohol/ n-heptane/water, with the increase of moisture content, the radius of inner water droplet Rw, the effective radius of particle Re, the length of interface 1 and the average aggregation number of surfactant n gradually increased. But the total interfacial area of dispersed phase Ad and the total particle count Nd gradually decreased in this systems. When n-Butanol was the cosurfactant, the system of -△G(?)linearly decrease. When medium chain alcohol and long chain alcohol was the cosurfactant, the system of-△G(?)decreased and then increased.As the carboatomic numbers of straight chain alcohol increased, the radius of inner water droplet Rw, the effective radius of particle Re, the length of interface 1, the average aggregation number of surfactant n and Gibbs Free Energy-△G(?) gradually increased. But the total particle count Nd and the total interfacial area of dispersed phase Ad gradually decreased.BaF2 and BaF2:Ce3+ nanoparticles were prepared from W/O microemulsion systems CTAB/n-butanol/n-heptane/water. BaF2 and BaF2:Ce3+ nanoparticles were nano spherical particles, and the diameter of BaF2 and BaF2:Ce3+ were about 38 nm by SEM. The Crystal Structure of the BaF2:Ce3+ nanoparticles was the same as the BaF2 nanoparticles by XRD. The BaF2:Ce3+ nanoparticles has broaded emission spectrum 300nm～400nm, peaked at 352nm, half-peak-width 60nm by fluorescence spectra. The BaF2:Ce3+ nanoparticles has broaded exciting spectrum 180nm～320nm, peaked at 285nm.