Synthesis and Thermodynamics of Perovskite Solid Solutions as Redox Materials for Solar-Thermochemical Processes

Kurzfassung

Perovskite oxides constitute a large and well known group of materials, with many valuable applications in research and technology. These materials are excellent candidates for application as redox materials in solar-thermochemical processes. Using concentrated solar power (CSP) as heat source, these oxides are non-stoichiometrically reduced at high temperature, followed by re-oxidation at lower temperatures or higher oxygen partial pressures. By this means, air can be separated thermochemically for the application in industrial processes, or fuels may be produced through preparation of hydrogen and carbon monoxide. The targeted design of materials based on their thermodynamic properties for one of the above-mentioned applications is of particular interest. By preparing solid solutions with the general composition AxB1-xMyN1-yO3-δ with A, B = Ca, Sr and M, N = Ti, Mn, Fe, Co, Cu using a modified Pechini method, [4] we show how their redox enthalpies and entropies as a function of the non-stoichiometry δ can be tuned by adjusting their composition. We demonstrate the formation of perovskite solid solutions for a large range of compositions. Furthermore, systematic materials screening was conducted both experimentally and theoretically using the infrastructure of The Materials Project in collaboration with the Lawrence Berkeley National Laboratory. By this means, it was possible to create a search engine for perovskite materials based on their redox properties, which allows finding the most efficient perovskite depending on the individual process conditions.