A family of solid oxides was reported which was based upon this parent compound. The latter had a different crystal structure to that of all other known oxide electrolytes which exhibited fast oxide-ion conduction. Like other ionic conductors, the material underwent a structural transition (at about 580C) which resulted in an increase in conductivity of almost 2 orders of magnitude. The conductivity was equal to about 0.06S/cm at 800C. This was comparable to that of stabilized zirconia. The structural similarity of La2Mo2O9 to β-SnWO4 suggested a structural model for the origin of the oxide-ion conduction. The substitution of a cation that had a lone pair of electrons, by a different cation that did not have a lone pair (and which had a higher oxidation state), was suggested to be an original means of designing other oxide-ion conductors.

Designing Fast Oxide-Ion Conductors Based on La2Mo2O9. P.Lacorre, F.Goutenoire, O.Bohnke, R.Retoux, Y.Laligant: Nature, 2000, 404, 856-60