Electrokinetic Research on the Dispersion Behavior of Nano-Ceria Particles in Concentrated Suspensions

Abstract

A multi-scale method was developed, which utilized intrinsic relationships among zeta potential of particles, rheological properties of suspensions and particle size distribution (PSD), to analyze dispersion behavior of nanoparticles in concentrated suspensions. It was found that PSD of a kind of nanoceria particles by dynamic light scattering (DLS) method in solution A with concentration 5 wt% accorded well with that by direct TEM analysis, which meant the particles had been dispersed well. However, there had a significant difference when the concentration was increased to 20 wt%. When particles concentration increased from 5 wt% to 20 wt%, zeta potential in solution A changed from-150 mV to-100 mV, while zeta potential in solution B changed from-35mV to-45 mV. Variations of zeta potential of particles accorded well with rheological properties of suspensions too, from phenomenological models. When the suspensions composed by solution A and the nanoparticles with concentration about 20 wt% was diluted with its original solution to 5 wt%, the PSD of nanoceria could be measured indirectly, which accorded well with both that of a suspension prepared directly with near concentration and that from TEM images. Then a method to measure PSD of nanoparticles in concentrated suspension was brought forward.

Synthesis of Hierarchical Layered Quasi-Triangular Ce(OH)CO3 and Its Thermal Conversion to Ceria with High Polishing Performance

“…A further increase of calcination temperature to 950 and 1000 °C resulted in a large melting zone and disappearance of the layered structure; thus, the specific surface area dropped sharply to 6.93 and 4.07 m 2 /g. The products obtained at calcination temperatures of 800−950 °C possessed ζ potential values of more than 30 mV, suggesting their good dispersion stability, 45,46 while for the product calcined at 1000 °C, its ζ potential value was 15.3 mV and the dispersion stability was poor. This may be related to the fact that the particles calcined at 1000 °C are denser due to large-area melting and the disappearance of layered edges; thus, the gravity effect is greater than that of the samples calcined at 800−950 °C.…”