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

J. VEGA CASTILLO; U. RAVELLA; G. CORBEL; PH. LACORRE; A. CANEIRO

JOURNAL OF THE CHEMICAL SOCIETY, DALTON TRANSACTIONS

Royal Society of Chemistry

Año: 2012 vol. 24 p. 7266 - 7271

0300-9246

Thermogravimetric analysis (TGA) technique in controlled oxygen partial pressure (pO2) atmospheres has been used to obtain equilibrium oxygen content data as a function of pO2 on the La2Mo2O9−δ 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 °C have been determined and discussed. At 608 °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).