Effects of Xerogel Synthesis on Physical and Chemical Properties of Nanopowder and Ceramic Materials in the CeO2–Dy2O3 System

Two methods of liquid-phase synthesis—coprecipitation of hydroxides and co-crystallization of nitrate salts—are used to synthesize highly dispersed mesoporous powder samples. The samples have the following composition: (CeO₂)_1–x(Dy₂O₃)_x (x = 0.05, 0.10, 0.15, 0.20) with a specific pore volume ranging between 0.028 and 0.086 cm³/g and a specific surface area of 22.68–66.32 m²/g. The powder obtained is used to make ceramic nanomaterials having designed composition. These are cubic fluorite type solid solutions having a coherent scattering region (CSR) of ~78–91 nm (1300°C). The open porosity varies between 2 and 14%. The apparent density is fairly high (5.87–7.05 g/cm³). Different effects of synthesis conditions influence the physics and chemical properties of the ceramic electrolyte materials. It is shown that the synthesis used to obtain sintering additive ZnO for ceramics controls open porosity and density in different manner: the open porosity drops 3–5 times and the density increases when the salt co-crystallization technique is used. However, it is shown that the porosity exhibits a decrease by 2 times in the samples synthesized using the hydroxide coprecipitation method, which confirms the selective effect of sintering additives. The new ceramic materials have physical and chemical properties (density, porosity, and coefficient of thermal expansion) making them promising for applications as solid oxide electrolytes in medium-temperature fuel cells.