Effect of alkaline-doping on the properties of La2Mo2O9 fast oxygen ion conductor

Synthesis by means of a modified Pechini method of pure and alkaline-doped (Na, K and Rb) La2Mo2O9 (LAMOX) is presented. The electrical conductivity of LAMOX prepared by this method is completely analogous to that of the solid state prepared material. Doping with K and Rb hinders the a A b phase transition found in the pure and Na-doped material around 580 uC. Electrical measurements as a function of pO2 shows that LAMOX has a mainly ionic conductivity down to 10218 atm. The electrical onductivity of the doped samples is close to that of the pure molybdate for temperatures higher than about 600 uC, while for K- and Rb-doped samples the conductivity is higher for lower temperatures, as a consequence of the absence of the phase transition. Finally, a non-Arrhenius behaviour is observed for all the investigated samples and correlated, at a first approximation, to the structural peculiarities of the LAMOX family.