Preparation Of CaF₂ Nanoparicles In W/O Microemulsion System

Various kinds of ordered micro-structures exist in reverse microemulsion, most of these ordered micro-structures are with in the nanoscale. They can provide a special microenvironment for chemical reactions, not only as a micro-reactor and also a template. In recent years, the surfactant system has become a novel preparation method for the nano-materials, widely used in the preparation of nanoparticles.Two different types of surfactants were used in this paper, ie non-ionic surfactant TX-100 and cationic surfactant CTAB. Calcium fluoride nanoparticles were prepared by the two kinds of reverse microemulsions.Cyclohexane, Triton X-100, hexanol and certain percentage of salt water solution were used to form clear and transparent microemulsion. Then a single micro-emulsion method was choosed to prepare the CaF2 powders, That is,aqueous solution of precipitating agent is slowly dropped to the former microemulsions. And, Fluorinated Powder coated with surfactant was prepared. The effects of different quality of the microemulsion solution were studied. and the final product was characterized by using XRD and particle size distribution of the powder.In the end, the infrared spectra of the powders calcinated at different temperatures (400℃,600℃, 800℃) was tested.The reverse microemulsion system comprised of CTAB/butanol/ heptane/water was used to the prepared the CaF2 powder. For a given microemulsion system, the main factors that have a great deal of influence on the final nanoparticles are as follows:the reaction temperature, aging (reaction) time, reactant concentration, cosurfactant and concentration mass ratio, water and surfactant molar ratio etc. For the reaction temperature, the selected three temperature points are 15℃, 25℃and 35℃, to ultrafine fluorinated Powder. the impact on the final powders and microemulsion system were studied. For the aging time, the characteristics of the powders. coated and modified by surfactant was investigated after aging Oh,5h,24h. For the concentration of reactants, the considered molar ratio of [Ca2+]/[F-] were 2:5,1:2,2:1. For the concentration of cosurfactant, the surfactant and cosurfactant mass ratio was was investigated at the same time, the CTAB/butanol (mass ratio)= 1:3,1:2,1:1. For the concentration of surfactant, the parameter of [H2O]/[CTAB] was examined, the values were respectively 10,15,20,25,30. And under these conditions, the morphology, agglomeration and Size distribution of powders were studied. In the end, the infrared spectra of the powders calcinated at different temperatures (400℃, 600℃,800℃) was tested.