Preparation of nanosize cerium oxide particles in W/O microemulsions

Cerium dioxide nanoparticles were synthesized in a toluene/CTABr/Ce(NO3)3/pentanol system using the microemulsion technique and ammonium hydroxide as hydrolyzing agent. Particle size was controlled by varying the molar ratio W = [water]/[surfactant], precursor concentration and surfactant carbon chain length. The molar ratio W was varied between 4 and 20, because model calculations had shown this range to be ideal for the synthesis of particles below 10 nm in size. Based on TEM measurements, particle size was in the range of 2.69–4.06 nm. Precursor ion concentration was varied in the range of 2.2–6.6 wt% (46.0–138 mM). The size of the droplets formed in the microemulsion was determined by dynamic light scattering. Structural studies on CeO2 and particle size determination were carried out by XRD. Thermal analysis of the samples prepared in W/O microemulsions is also presented. The specific surface area of the samples was 53.53–128.65 m2/g and their average pore size as determined by pore size distribution measurements was 1.73–4.91 nm.