The
La2Mo2O9–La2Mo3O12 composite materials represent a novel
class of highly conductive materials demonstrating increased oxygen-ion
conductivity. Extensive research of (100 – x)La2Mo2O9–xLa2Mo3O12 composites over a wide
range of concentrations (x = 5, 10, 15, 20, 30, and
100) was carried out for the first time. An increase in conductivity,
oxygen surface exchange coefficient, and oxygen diffusivity is observed
for composites compared to individual oxides, which is associated
with the segregation of different ions on the surface of the grains
and the formation of a La5Mo3O16 new
phase at the contact boundary of La2Mo2O9 and La2Mo3O12. 3D-modeling
of the composite microstructure was performed on the basis of SEM-image
analysis data in order to estimate the conductivity of the interphase
layer between the La2Mo2O9 and La2Mo3O12 grains containing La5Mo3O16. The electrical conductivity values
of the composite materials calculated from a 3D-simulated microstructure
and the experimentally measured conductivity correlate and demonstrate
a composite effect.