Preparation and characterization of sol-gel derived (ThxCe1−x)O2 microspheres

Abstract

Abstract (ThxCe1−x)O2 microspheres (x=0.50, 0.75 and 0.95) with high homogeneity were prepared via sol-gel technique, starting from the initial chemical materials Th(NO3)4·5H2O and (NH4)2[Ce(NO3)6]. The sols were prepared by addition of ammonia under pH and temperature control. Sols were gelated to spherical form in a gelation system consisting of peristaltic pump, flow regulator, nozzle and a glass column. To obtain crack-free spheres suitable for gelation, source sols neutralization conditions, drop formation and pre-hardening medium were investigated and the optimum conditions were determined. After aging, washing and drying steps, gel microspheres were characterized. For this purpose, thermal behaviors of spheres were investigated with TG/DTA analysis. Dried microspheres at 80°C were calcined at three different temperatures, namely 450°C, 800°C and 1150°C, and crystal parameters were calculated from XRD data. BET specific surface area and BJH porosity analyses were also carried out.