Novel way of phase stability of LSGM and its conductivity enhancement

Instead of using various methods to synthesize phase pure Sr- and Mg-doped LaGaO3 (LSGM), it is very interesting to achieve phase purity by changing the stoichiometry and additional co-doping. In this work, Pechini method is adopted to synthesize LSBGM (La0.8Sr0.2−xBaxGa0.8Mg0.2O2.8) by co-doping of Ba2+ and Sr2+ at La-site, and Mg2+ at Ga site. These multi-dopings eliminate the complexities in the synthesis and processing techniques, and desired single phase is achieved more easily. Tolerance factor, which is a measure of structural symmetry, increases from 0.9622 (in LSGM) to 0.9652 (in LSBGM). Moreover, an increase in 0.4% free volume occurred due to these multiple dopings at La-site. Enhancement in free volume and structural symmetry attribute to a higher ionic conductivity of LSBGM, which is also supported by XPS analysis. Ionic conductivity (0.046 S/cm at 600 °C) measured by impedance spectroscopic analysis is found to be >44% superior compared to the LSGM synthesized by similar/different processes. Additionally, a decrease in activation energy value suggests the lower vacancy-dopant interaction in LSBGM.