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Synthesis and characterization of tungsten and barium co-doped La2Mo2O9 by sol-gel process for solid oxide fuel cellsHerein, we demonstrate the synthesis of W and Ba co-doped La2Mo2O9 (LBMWO) nanocrystalline powder by a sol-gel process. In all the compositions have general formulae La1.9Ba0.1Mo2–xWxO8.95 (x = 0–0.40). The crystal structure, microstructure and conductivity of LBMWO were characterized by X-ray diffraction, scanning electron microscopy and electrical impedance spectroscopy. In addition, the thermal and decomposition properties of the LBMWO gel were analyzed by differential scanning calorimetry - thermogravimetric. The results reveal that all LBMWO powders calcined at 700 °C have a cubic structure; the average crystallite size is about 48 nm. The unit cell parameter of LBMWO powders increases with increase in W content. The as-synthesized nanocrystalline LBMWO samples exhibit excellent sinterability and a relatively lower sintering temperature of 900 °C. A high relative density of ∼96% is achieved after sintering at 900 °C which is in good agreement with the results of the SEM. Moreover, W and Ba co-doping suppresses the phase transition and effectively stabilizes the β-phase at low temperature. At the same time, La1.9Ba0.1Mo1.85W0.15O8.95 exhibits high ionic conductivity, 3.07 × 10−2 S/cm at 800 °C. It is therefore concluded that co-doping can improve the properties of La2Mo2O9 electrolytes.