Thermodynamic stability, structural and electrical characterization of mixed ionic and electronic conductor La 2Mo 2O 8.96

Abstract

Thermogravimetric 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 La 2Mo 2O 9-δ system resulting from the partial reduction of fast oxide-ion conductor La 2Mo 2O 9 (LM). Thermodynamic conditions for stabilization of crystalline La 7Mo 7O 30 and amorphous La 2Mo 2O 7-y at 718 °C have been determined and discussed. At 608 °C, the compound reported for the first time La 2Mo 2O 8.96 (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). © 2012 The Royal Society of Chemistry.