TY - JOUR
T1 - Thermochemistry of Sr 2Ce 1-xPr xO 4 (x = 0, 0.2, 0.5, 0.8, and 1)
T2 - Variable-temperature and -atmosphere in-situ and ex-situ powder x-ray diffraction studies and their physical properties
AU - Kan, Wang Hay
AU - Thangadurai, Venkataraman
PY - 2012/8/20
Y1 - 2012/8/20
N2 - A novel family of metal oxides with a chemical formula of Sr 2Ce 1-xPr xO 4 (x = 0, 0.2, 0.5, 0.8, and 1) was developed as mixed oxide ion and electronic conductors for solid oxide fuel cells (SOFCs). All of the investigated samples were synthesized by the ceramic method at 1000 °C in air and characterized by powder X-ray diffraction (PXRD), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and electrochemical impedance spectroscopy (EIS). Ex-situ PXRD reveals that the Sr 2PbO 4-type Sr 2CeO 4 decomposes readily into a mixture of perovskite-type SrCeO 3 and rock-salt-type SrO at 1400 °C in air. Surprisingly, the decomposed products are converted back to the original Sr 2PbO 4-type Sr 2CeO 4 phase at 800 °C in air, as confirmed by in-situ PXRD. Thermal decomposition is highly suppressed in Sr 2Ce 1-xPr xO 4 compounds for Pr > 0, suggesting that Pr improves the thermal stability of the compounds. Rietveld analysis of PXRD and SAED supported that both Pr and Ce ions are located on the 2a site in Pbam (space group no. 55). The electrical transport mechanism could be correlated to the reduction of Pr and/or Ce ions and subsequent loss of oxide ions at elevated temperatures, as shown by TGA and in-situ PXRD. Conductivity increases with Pr content in Sr 2Ce 1-xPr xO 4. The highest total conductivity of 1.24×10 -1 S cm -1 was observed for Sr 2Ce 0.2Pr 0.8O 4 at 663 °C in air.
AB - A novel family of metal oxides with a chemical formula of Sr 2Ce 1-xPr xO 4 (x = 0, 0.2, 0.5, 0.8, and 1) was developed as mixed oxide ion and electronic conductors for solid oxide fuel cells (SOFCs). All of the investigated samples were synthesized by the ceramic method at 1000 °C in air and characterized by powder X-ray diffraction (PXRD), selected area electron diffraction (SAED), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and electrochemical impedance spectroscopy (EIS). Ex-situ PXRD reveals that the Sr 2PbO 4-type Sr 2CeO 4 decomposes readily into a mixture of perovskite-type SrCeO 3 and rock-salt-type SrO at 1400 °C in air. Surprisingly, the decomposed products are converted back to the original Sr 2PbO 4-type Sr 2CeO 4 phase at 800 °C in air, as confirmed by in-situ PXRD. Thermal decomposition is highly suppressed in Sr 2Ce 1-xPr xO 4 compounds for Pr > 0, suggesting that Pr improves the thermal stability of the compounds. Rietveld analysis of PXRD and SAED supported that both Pr and Ce ions are located on the 2a site in Pbam (space group no. 55). The electrical transport mechanism could be correlated to the reduction of Pr and/or Ce ions and subsequent loss of oxide ions at elevated temperatures, as shown by TGA and in-situ PXRD. Conductivity increases with Pr content in Sr 2Ce 1-xPr xO 4. The highest total conductivity of 1.24×10 -1 S cm -1 was observed for Sr 2Ce 0.2Pr 0.8O 4 at 663 °C in air.
U2 - 10.1021/ic301071x
DO - 10.1021/ic301071x
M3 - Article
AN - SCOPUS:84865266097
SN - 0020-1669
VL - 51
SP - 8973
EP - 8981
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 16
ER -