Studies on electrical properties of La_0.8Sr_0.2Ga _0.8Mg_0.2O_2.80 (LSGM) and LSGM-SrSn _1-xFe_xO₃ (x = 0.8; 0.9) composites and their chemical reactivity

We report the electrical conductivity properties of solid-state synthesized perovskite-like La_0.8Sr_0.2Ga_0.8Mg _0.2O_2.80 (LSGM) and LSGM-SrSn_1-xFe _xO₃ (x = 0.8; 0.9) composites. LSGM exhibits both bulk and grain-boundary contribution in the ac impedance plots. The grain-boundary conductivity (σ_gb) is slightly (≤half-order of magnitude) higher than that of the bulk oxide ion conductivity (σ_bulk). Powder XRD study reveals that no chemical reaction occurs between LSGM and SrSn_1-xFe_xO₃ (1:1 wt.%) at 1000 °C (48 h) and forms a single-phase perovskite-like compound at 1300 °C (48 h) in air, while in hydrogen atmosphere, at 800 °C for 48 h, a growth of LaSrGaO ₄ and LaSrGa₃O₇ impurity phases and formation of metallic Fe was observed. The LSGM-SrSn_1-xFe_xO ₃ (x = 0.8; 0.9) composites show a single or part of semicircle in air at low-temperature regime. The electrical conductivity of the composites were found to be much higher compared to pure LSGM and lower about an order of magnitude than those of pure Sn-doped SrFeO₃ perovskite.