Maltose and pectin assisted sol–gel production of Ce0.8Gd0.2O1.9 solid electrolyte nanopowders for solid oxide fuel cells

Abstract

A novel sol–gel method has been developed for the production of high purity nanopowders of cerium gadolinium oxide (CGO, Ce0.8Gd0.2O1.9) solid solution using maltose as an organic chelating agent and pectin for gelation. The results of this investigation indicate that the final particle size of approximately 10 nm can be obtained after calcination of the predried gel at 500 °C for 2 hours in ambient air. An insight into the calcination process has been obtained by using simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). Powder X-ray diffraction (XRD) confirms that all samples are single phase cubic CGO powders with no trace of impurity. The mean crystallite sizes calculated from XRD analysis using the Rietveld refinement method agree with the morphological features observed by transmission electron microscopy (TEM). The nanopowders produced in this study exhibit negligible strain as indicated by the Rietveld refinement procedure. The nominal composition of CGO has been found to be in excellent agreement with that determined by energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma-atomic emission spectrometry analysis (ICP-AES). The XRD and TEM analyses indicate that there is a significant influence of calcination temperature on the particle size which increases with increasing temperature for a fixed annealing time. This new sol–gel method is a cost effective, simple, environmentally friendly and non-toxic route for a large scale production of high purity single phase nanopowders of complex oxide functional ceramic materials at significantly low temperatures.