Synthesis and microstructural characterization of Sr- and Mg-substituted LaGaO 3 solid electrolyte

Abstract

Sr and Mg substituted LaGaO 3 is a solid electrolyte for intermediate temperature solid oxide fuel cell. Phase purity of this material is a concern for the researchers for a long time. In this contribution the secondary phases that are evolved during the synthesis of Sr and Mg doped LaGaO 3 are reported. For that purpose, a series of La 1− x Sr x Ga 1− y Mg yO 3− δ (LSGM) was prepared by solid state synthesis route. Scanning electron microscopic photographs showed secondary phases namely La 4Ga 2O 9, LaSrGa 3O 7, LaSrGaO 4 along with the parent perovskite LSGM depending upon the amount of dopant. Amount of secondary phases was estimated from the peak positions of room temperature X-ray diffraction. It was observed that for a fixed amount of Mg dopant increasing the amount of Sr content also increased the amount of secondary phases whereas the reverse was found to be true when Sr content was fixed and Mg content was increased. This behaviour was attributed to the increase in solid solubility of Sr in presence of Mg.