The Influence of the Conditions of Synthesis and Consolidation of Nanopowders on the Physicochemical Properties of Solid Solutions in the (CeO2)1 – x(Dy2O3)x System as Electrolytes for Medium-Temperature Fuel Cells

Abstract

Using liquid-phase methods of coprecipitation of hydroxides and cocrystallization of nitrate salts, highly dispersed powders of the (CeO₂)_1 – x(Dy₂O₃)_x (x = 0.05, 0.10, 0.15, 0.20) composition are synthesized. On their basis, ceramics, which are cubic solid solutions of the fluorite type with a coherent scattering region (CSR) of ~90 nm (1300°С) with open porosity in the range of 2–14% and apparent density of 6–7 g/cm³, are obtained. The influence of methods of synthesis and sintering additives on the physicochemical and electrophysical properties of ceramics is studied. It is established that the obtained ceramics have a predominantly ionic type of electrical conductivity (ion transport numbers t_i = 0.78–0.96 in the range of 300–700°С). Electrical conductivity in solid solutions is realized by the vacancy mechanism and reaches the value of σ_700°С = 0.43 × 10^–2 S/cm. Based on their physical and chemical properties (density, open porosity, type and mechanism of specific electrical conductivity), the obtained ceramic materials are promising as solid oxide electrolytes for medium-temperature fuel cells.