Preparation and characterisation of perovskite La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 electrolyte using a poly(vinyl alcohol) polymeric method

The perovskite La_0.8Sr_0.2Ga_0.83Mg_0.17O_2.815 (LSGM) fuel cell electrolyte was prepared by a polymeric method using poly(vinyl alcohol) (PVA). The LSGM precursor powder was examined by thermogravimetric and differential thermal analysis (TG/DTA) and Fourier transform infrared (FTIR) spectroscopy. It was found that thermal decomposition of the LSGM precursor powder occurs in a number of different stages, and complete decomposition of the precursor is obtained at 1000 ℃. X-ray diffraction (XRD) showed that calcined powder contains three secondary phases, namely La₄Ga₂O₉, LaSrGa₃O₇, and LaSrGaO₄, even after calcination at 1100 ℃. Furthermore, the fraction of secondary phases decreases with increasing calcination temperature. Single phase perovskite LSGM pellets with a relative density of 97% were obtained after sintering at 1450 ℃ for 10 h. It was therefore shown that the powder prepared by the simple PVA method is fine, highly reactive, and sinterable. The electrical properties of LSGM pellets were characterised by impedance spectroscopy. The conductivity of the LSGM pellets sintered at 1450 ℃ for 10 h was 8.24×10^-2 S/cm at 800 ℃.