Preparation and characterization of solid electrolytes La2−xAxMo2−yWyO9 (A=Sm, Bi)

Based on the oxygen ion conductor La2Mo2O9, a series of Sm-doped substitutes (La2−xSmxMo2O9, x=0.1, 0.2, 0.3, 0.4) were prepared. The structure, influence of phase transition and oxygen ion conductivity were studied with DSC, HRTEM, high temperature and room temperature XRD, and complex impedance spectra. For comparison, Bi-doped substitutes (La2−xBixMo2O9, x=0.1, 0.2, 0.3, 0.4) were also prepared and studied. Experimental results showed that the substitution of La with appropriate amount of Sm can effectively stabilize the β-form of La2Mo2O9 at room temperature and inhibit its phase transition to α-form, and therefore presented the substitutes much higher ionic conductivity than the pristine La2Mo2O9. In addition, co-substitution of both La and Mo sites were achieved with Sm or Bi and W, and typical substitutes La2Mo1.7W0.3O9, La1.7Sm0.3Mo1.7W0.3O9 and La1.7Bi0.3Mo1.7W0.3O9 were obtained, which to some extent improved the ionic conductivity of La2Mo2O9, especially at lower temperatures.