Electrical and thermal properties of La0.7Sr0.3Ga0.6Fe0.4O3 ceramics

Single-phase La0.7Sr0.3Ga0.6Fe0.4O3 (LSGF) ceramic powder was prepared in one step at 1500 °C by solid-state reaction in air. The phase is a hexagonal (space group R-3c) at room temperature but becomes cubic at temperatures above ∼600 °C. A high-density (97%) LSGF ceramic shows electrical conductivity of 4.3 S/cm (Ea = 0.32 eV) at 600 °C in air. The thermal expansion coefficient of LSGF changes drastically in air due to oxygen loss and phase transition. High-density LSGF ceramic is relatively stable in forming gas (8% H2, 92% Ar). However, the powder decomposes in forming gas above 700 °C with formation of LaSrGaO4. LSGF reacts with NiO at 1000 °C. The ability of LSGF to split the CH bond in methane at intermediate temperatures has been also evaluated.