Renewable Energy Sources, Hydropower Materials for Fuel Cells Based on Barium and Strontium Cobaltites Synthetized on a Solar Furnace

Study was carried out on materials based on perovskite structures of cobaltite compositions of strontium and barium obtained by synthesis from a melt of a stoichiometric mixture of cobalt oxide with strontium carbonates Co 2 O 3 + SrCO 3 or barium Co 2 O 3 + BaCO 3 in a stream of high (150 W/cm 2 ) density concentrated solar radiation in a solar furnace, followed by quenching in water and sintering at a temperature of 1300 K. Hexagonal barium and strontium cobaltites had a developed fine microstructure (grains in the form of densely packed polyhedrons of various shapes 2–5 μm in size), a semiconductor character of electrical conductivity, and a low thermal expansion coefficient (average 12.6 × 10 –6 K –1 ) in the temperature range 300–1100 K. The change in the electrical resistance of materials is due to the high affinity of cobalt ions for oxygen, which causes oxygen sorption and, as a result, leads to changes in the electronic structure of cobalt ions, as a result of charge transitions 2Co 3+ = Co 2+ + Co 4+ . This circumstance indicates the possibility of using materials based on barium and strontium cobaltites as selective absorbers, oxygen membranes, or cathode materials for the manufacture of solid-oxide fuel cells in the production of electrical energy as well as materials for hydrogen storage.