Synthesis and characterization of tungsten and barium co-doped La2Mo2O9 by sol-gel process for solid oxide fuel cells

Abstract Herein, we demonstrate the synthesis of W and Ba co-doped La 2 Mo 2 O 9 (LBMWO) nanocrystalline powder by a sol-gel process. In all the compositions have general formulae La 1.9 Ba 0.1 Mo 2– x W x O 8.95 ( 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, La 1.9 Ba 0.1 Mo 1.85 W 0.15 O 8.95 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 La 2 Mo 2 O 9 electrolytes.