Synthesis of La0.85Sr0.15Ga0.8Mg0.2O3 − δ powder by carbonate co-precipitation combining with azeotropic-distillation process

Abstract

La0.85Sr0.15Ga0.8Mg0.2O3−δ (LSGM1520) powder is synthesized by a carbonate co-precipitation coupling with azeotropic-distillation process. The composition of the as-prepared precipitate is determined by X-ray diffraction (XRD), elemental analysis (EA), thermogravimetric and differential scanning calorimeter (TG-DSC) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The post-distilled precursor is submitted to various thermal treatments and characterized by XRD and transmission electron microscopy (TEM). The results show that the components of the powder calcined at 1000°C contain a main perovskite phase and small amounts of secondary phases (namely LaSrGaO4 and LaSrGa3O7). TEM observation reveals that the powder has a narrow grain size distribution, which turns out to be suitable for sintering (>97% relative density for a pellet sintered at 1400°C during 4h). The conductivity of sintered pellets is measured and the highest conductivity at 800°C of LSGM1520 is 0.186Scm−1, which is nearly three times as high as that of La0.8Sr0.2Ga0.8Mg0.2O3−δ (0.0644Scm−1) prepared by the similar carbonate method. It suggests that a new route of synthesizing Sr- and Mg-doped lanthanum gallate (LSGM) with good sinterability has been developed.