Synthesis of SrAl2 O4 nanoparticles by reverse micelle method:An investigation of the effect of aging time, hydrophilic chain length and calcination temperature

Abstract

Abstract Three types of non-ionic Triton X-series surfactants with different hydrophilic chain lengths (oxyethylene groups) were used to prepare SrAl2O4 nanoparticles by a reverse micelle method. The size, structure, and morphology of the SrAl2O4 nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). It was found that increasing the aging time had no obvious influence on the particle shape and the crystal-phase distributions, but greatly affected the average crystallite size of the final product and led to the formation of larger spherical particles. Furthermore, an increase in hydrophilic chain lengths corresponded with a decrease in both crystallite and particle size, whereas a further dramatic increase in hydrophilic chain lengths resulted in an increase in crystallite and particle size. This unexpected observation was attributed to the deformability in the film of surfactant Triton X-405, which in turn resulted in a reduction in the intermicellar exchange rate. Therefore, it was concluded that final particle size is influenced by both water pool size and intermicellar exchange rate. Although the synthesized SrAl2O4 nanoparticles calcined at 800 and 1000\xa0°C revealed a monoclinic phase, both hexagonal and monoclinic phases were observed when the calcination temperature increased to 1200\xa0°C.