Preparation, electrical and thermal properties of new anode material based on Ca-doped perovskite CeAlO3

Tetragonal perovskite phase Ce0.9Ca0.1AlO2.95 + x was obtained for the first time. Such phase, containing cerium in the oxidation state of 3+, can be promising anode materials for a solid oxide fuel cells (SOFCs). Ce0.9Ca0.1AlO2.95 + _ (space group I4/mcm) was synthesized by the solid-phase method at 1400 & DEG;C in a nitrogen flow with using ammonium oxalate (NH4)2C2O4 to create a reducing atmosphere. Thermogravimetry results showed that Ce0.9Ca0.1AlO2.95 + x was stable to oxidation up to 500 & DEG;C in air and up to 700 & DEG;C in argon (partial pressure of oxygen pO2 =10-4 bar). The thermal expansion coefficient measured by dilatometry was equal to 11.16.10-6 K-1. The temperature dependences of the electrical conductivity (for undoped phase CeAlO3 s = 1.10-3 S/cm and for doped Ce0.9Ca0.1AlO2.95 + x s = 3.10-2 S/cm at 500 & DEG;C in air) were obtained by the electrochemical impedance spectroscopy measurements). The electrical conductivity of these samples at the temperatures range of 350-500 & DEG;C was almost independent of the partial pressure of oxygen pO2 from 10-18 to 0.21 bar, however, there was a slight negative slope at T > 500 & DEG;C (pO2). The total ionic transport numbers measured by the EMF method were close to 1.10-3, which indicated the dominance of electronic conductivity. The measurement of the sign of the thermal-EMF showed that positive charge carriers (holes) were dominant charge carriers.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

For the first time, the tetragonal perovskite phase Ce0.9Ca0.1AlO2.95 + x, containing cerium in the oxidation state of 3+, was synthesized and shows potential as an anode material for solid oxide fuel cells. The phase is stable up to 500°C in air and up to 700°C in argon. The electrical conductivity is primarily influenced by electronic conductivity and shows little sensitivity to the partial pressure of oxygen.