Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La2Mo2O8.96

International audienceThermogravimetric analysis (TGA) technique in controlled oxygen partial pressure (pO(2)) atmospheres has been used to obtain equilibrium oxygen content data as a function of pO(2) on the La2Mo2O9-delta system resulting from the partial reduction of fast oxide-ion conductor La2Mo2O9 (LM). Thermodynamic conditions for stabilization of crystalline La7Mo7O30 and amorphous La2Mo2O7-y at 718 degrees C have been determined and discussed. At 608 degrees C, the compound reported for the first time La2Mo2O8.96 (LM896) has been found. The crystalline form and transition temperature in LM896 have been identified by X-ray diffraction at room temperature (XRD) and at controlled temperature. Conductivity curves obtained by electrochemical impedance spectroscopy (EIS) as a function of temperature for both LM and LM896 have been compared. The results indicate that LM896 is a mixed ionic and electronic conductor (MIEC)