Comparative analysis of the influence of xerogel synthesis methods on the physicochemical properties of nanopowders and ceramic materials of the CeO2 – Dy2O3 system

Highly dispersed mesoporous powders of the composition: (CeO2)1 – x(Dy2O3)x (x = 0.05; 0.10; 0.15; 0.20) with a specific pore volume of 0.028–0.086 cm3/g and a specific surface area of 22.68 – 66.32 m2/g were synthesized using different methods of liquid-phase synthesis: coprecipitation of hydroxides and cocrystallization of nitrate salts. On their basis, ceramic nanomaterials of a given composition were obtained, which are cubic solid solutions of the fluorite type with a CSR of ~ 78 – 91 nm (1300 °С), with an open porosity in the range of 2–14%, high values of apparent density of 5.87 – 7.05 g/cm3. The different influence of synthesis conditions on the physicochemical properties of ceramic electrolyte materials was revealed. It was shown that the sintering additive ZnO for ceramics obtained by different synthesis methods affects the open porosity and density differently: in the case of using the method of joint crystallization of salts, the open porosity decreased by 3 – 5 times, the density increased. However, for samples synthesized by the method of co-precipitation of hydroxides, the porosity decreased by 2 times, which proves the selective influence of sintering additives. In terms of their physicochemical properties (density, porosity, coefficient of thermal expansion), the obtained ceramic materials are promising as solid oxide electrolytes for medium-temperature fuel cells.