Industrial mass production of nanocrystalline Ce0.9Gd0.1O1.95 via a solid-liquid method using gluconic acid

To achieve industrial mass production, a simple and efficient solid-liquid method (SLM) was applied to synthesize nanocrystalline gadolinium-doped ceria (Ce0.9Gd0.1O1.95, GDC), using gluconic acid (GA) as a complexing agent and polyethylene glycol (PEG) as a surfactant. Unlike traditional wet-chemical methods, this method of forming metal-complex compounds does not involve heating processes, which are known to pose risks of fire and explosion. The substitution of GA for traditional citric acid (CA) reduces the corrosion of stainless steel equipment. The effects of the varying amounts of GA and polymerization degrees of PEG were discussed. The physical properties of the precursors were characterized using thermogravimetry/differential thermal analysis (TG/DTA). The crystallinity and grain size of the GDC powders were analysed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), and particle-size distribution (PSD) analyses. The results show that the GDC powder with additions of 20 wt% GA and 1 wt% PEG2000 that was sintered at 800 degrees C has a single phase with a particle size of around 40 nm; it is also homogenous and highly pure. In addition, the ionic conductivity of the GDC pellet that was sintered at 1450 degrees C for 5 h is 0.046 S/cm at 750 degrees C. These results indicate that this novel SLM is suitable for the mass synthesis of high-performance nanocrystalline Ce0.9Gd0.1O1.95 powders.