Formation of Nanoparticles Controlled by the Yield and Properties of the γ-Generated Radicals

In the past two decades, nanoparticles have attracted much attention because of their novel properties. Among the numerous synthetic methods, ionizing irradiation, which is simple and can take at normal temperature and pressure, even at low temperature, is a powerful method for preparing metals, alloys, metal oxides, metal chalcogenides, metal halides and insoluble sulphate nanoparticles. In this method, dose rate is always used to affect the shape, component and size of synthesized nanoparticles. In addition, to eliminate the effect of ·OH on the formation of nanoparticles, alcohol (such as isopropyl alcohol) is always added and a lot of reductive radicals with wide range of reduction potentials are generated. At the same time, these radicals transformed from ·OH can also reduce the reactant, which have been used to control the growth of nanoparticles. However, so far, most nanoparticles synthesized by ionizing irradiation are spherical. In our previous work, ''solid'' BaSO4 microspheres, mainly consisting of quasi-spherical nanoparticles, have been synthesized by precipitating Ba2+ ions with SO42- ions, which were generated from the reduction of K2S2O8 in the presence of EDTA under N2 atmosphere by γ-irradiation