High-temperature thermodynamic and transport properties of the Sr3Fe2O6þd mixed conductor

L. MOGNI; J. FOULETIER; F. PRADO; A CANEIRO

JOURNAL OF SOLID STATE CHEMISTRY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2005 vol. 178 p. 2715 - 2723

0022-4596

We report a systematic study of the non-stoichiometry and high-temperature transport properties of the perovskite related mixedconductor Sr3Fe2O6þd. The variation of the oxygen content ð6 þ dÞ with T and equilibrium oxygen partial pressure ðpO2Þ wasobtained by thermogravimetry within the range: 105opO2o1 atm:; 400pTp1100 C. From the experimental values of the oxygenchemical potential (mO2), the partial molar enthalpy (hO2 ) and the partial molar entropy (sO2 ) were determined for the compositionrange 6:00o6 þ do6:55. A simple defect model based on the mass action law assuming localized charge carriers and oxygenvacancies was used to reproduce the thermodynamic data.Electrical resistivity measurements as a function of pO2 at constant temperature were obtained within the interval650pTp1000 C. The activation energy values for the electrical transport process at constant oxygen content values wereobtained from the combination of electrical conductivity and thermogravimetry data. The electrical transport data are in agreementwith the small polaron model.