Colloidal stability of gadolinium-doped ceria powder in aqueous and non-aqueous media

In this work the colloidal behaviour of Ce0.9Gd0.1O2−δ powder in aqueous and non-aqueous media (ethanol) is studied. Commercial powder was characterised by particle size distribution, specific surface area measurements, X-ray diffraction and scanning electron microscopy. Diluted suspensions were characterised by particle size distribution and zeta potential, using dynamic light scattering and laser Doppler velocimetry principles, respectively. The solubility of the powder in water as a function of pH was analysed by inductively coupled plasma atomic emission spectrometry. Colloidal stability was studied as a function of pH, type and concentration of dispersants (polyacrylic-based deflocculant in water and a phosphate ester in ethanol). The time stability of the suspensions was analysed by multiple light scattering. The most stable suspension was obtained with a phosphate ester content of 2.0 wt% in ethanol. Finally, preliminary coatings have been obtained by dip coating using concentrated suspensions, which could be accessible to industrial scale so that they can be used as interlayers in solid oxide fuel cells.