High-Temperature Protonic Conduction in LaFeO3 – SrFeO3 − δ – SrZrO3 Solid Solutions

The electrical conductivity of a pseudoternary system, consisting of LaFeO 3 -SrFeO 3-δ -SrZrO 3 , {La 0.05(1-x) Sr 0.95+0 . 05x } (Zr 0.95 Fe 0.05 )O 3-δ (x = 0-0.5), was evaluated both in oxygen and hydrogen containing environments by a two-probe ac technique. Correlations of oxygen partial pressure, water vapor pressure, and composition dependences of the electrical conductivities with possible defect concentrations are examined by a semiquantitatively derived Brouwer diagram. In oxygen for x below 0.25, major carriers were identified to be oxide ions and electron holes, while for x = 0.5 they were a mixture of oxide ions, electron holes, and protons. In a hydrogen containing environment, the oxides with compositions for x = 0.25 and 0.5 were unstable. Thus, the electrical conductivity was analyzed in detail for x = 0.1. It was found that the oxide conducts protons significantly at temperatures below 1273 K, which was evidenced by the isotope effect of hydrogen and deuteron on the electrical conductivity. The electrical conductivity of the oxide increased with decreasing oxygen partial pressure due to the variation of oxygen nonstoichiometry, accompanied by partial reduction of Fe ions in the oxide. The transport number of proton increased as the oxygen partial pressure decreased. The gas partial pressure and the composition dependences of the electrical conductivity and the transport number of proton could be well explained by the conceptual Brouwer diagram proposed in this work.

[1]  H. Matsumoto,et al.  Electrical conduction and mass transport properties of SrZr0.99Fe0.01O3 − δ , 2010 .

[2]  O. Safonova,et al.  Decomposition of Carbon Dioxide at 500 °C over Reduced Iron, Cobalt, Nickel, and Zinc Ferrites: A Combined XANES−XRD Study , 2009 .

[3]  Y. Aoki,et al.  High proton conductivity in anodic ZrO(2)/WO(3) nanofilms. , 2009, Angewandte Chemie.

[4]  Y. Orikasa,et al.  Investigation on Oxygen Potential Distribution in a ZrO2-Based Solid Electrolyte by Using In-Situ Micro XAS Technique , 2009 .

[5]  Y. Orikasa,et al.  Electronic and Local Structures of La1-x SrxCoO3-δ Studied by In-Situ Micro XAS Measurements , 2008 .

[6]  H. Matsumoto,et al.  Slow relaxation kinetics of Sr(Zr, Y)O3 in wet atmosphere , 2008 .

[7]  N. Kitamura,et al.  Oxygen nonstoichiometry of the perovskite-type oxides BaCe0.9M0.1O3 − δ (MY, Yb, Sm, Tb, and Nd) , 2008 .

[8]  Manfred Martin,et al.  Unprecedented Room‐Temperature Electrical Power Generation Using Nanoscale Fluorite‐Structured Oxide Electrolytes , 2008 .

[9]  H. Matsumoto,et al.  Hydrogen permeability and electrical properties in oxide composites , 2008 .

[10]  T. Tsurui,et al.  Microstructures and grain boundary conductivity of BaZr1−xYxO3 (x = 0.05, 0.10, 0.15) ceramics , 2007 .

[11]  H. Matsumoto,et al.  Relation between electrical conductivity and chemical stability of BaCeO3-based proton conductors with different trivalent dopants , 2007 .

[12]  H. Matsumoto,et al.  Hydrogen separation from syngas using high-temperature proton conductors , 2007 .

[13]  H. Matsumoto,et al.  Influence of the transition-metal doping on conductivity of a BaCeO3-based protonic conductor , 2005 .

[14]  H. Matsumoto,et al.  Protonic-Electronic Mixed Conduction and Hydrogen Permeation in BaCe0.9 − x Y 0.1Ru x O 3 − α , 2005 .

[15]  H. Matsumoto,et al.  Mixed Protonic-Electronic Conduction Properties of SrZr 0.9− x Y 0.1 Ru x O 3− α , 2004 .

[16]  K. Amezawa.  High temperature protonic conduction in Ca-doped YPO4 , 2003 .

[17]  Joachim Maier,et al.  Proton conducting alkaline earth zirconates and titanates for high drain electrochemical applications , 2001 .

[18]  K. Sasaki,et al.  Re-analysis of defect equilibria and transport parameters in Y2O3-stabilized ZrO2 using EPR and optical relaxation , 2000 .

[19]  G. Alberti,et al.  Proton conductivity of mesoporous zirconium phosphate pyrophosphate , 1999 .

[20]  K. Kreuer.  Aspects of the formation and mobility of protonic charge carriers and the stability of perovskite-type oxides , 1999 .

[21]  K. Kreuer,et al.  On the development of proton conducting materials for technological applications , 1997 .

[22]  A. Nowick,et al.  Isotope effect and proton hopping in high-temperature protonic conductors , 1997 .

[23]  N. Nicoloso,et al.  Local structure and oxygen transport in transition metal doped YSZ , 1995 .

[24]  K. Knight,et al.  Perovskite solid electrolytes: Structure, transport properties and fuel cell applications , 1995 .

[25]  R. Waser,et al.  Optical absorption relaxation applied to SrTiO3 and ZrO2: An in-situ method to study trapping effects on chemical diffusion , 1994 .

[26]  J. Schoonman,et al.  Synthesis of strontium and barium cerate and their reaction with carbon dioxide , 1993 .

[27]  Srikanth Gopalan,et al.  Thermodynamic Stabilities of SrCeO3 and BaCeO3 Using a Molten Salt Method and Galvanic Cells , 1993 .

[28]  J. Mizusaki.  Nonstoichiometry, diffusion, and electrical properties of perovskite-type oxide electrode materials , 1992 .

[29]  T. Yogo,et al.  Protonic conduction in SrZrO3-based oxides , 1992 .

[30]  J. Mizusaki,et al.  Nonstoichiometry and defect structure of the perovskite-type oxides La1−xSrxFeO3−° , 1985 .

[31]  忠 笹本,et al.  空気中におけるSrZrO3-LaFeO3-SrFeO3-δ系ペロブスカイ型固溶体の相関係と電気伝導度 , 1982 .

[32]  H. Iwahara,et al.  Proton conduction in sintered oxides and its application to steam electrolysis for hydrogen production , 1981 .

[33]  H. Bowen,et al.  Electrochemical Degradation of Ceramic Electrodes , 1980 .

[34]  M. Ahtee,et al.  The structure of orthorhombic SrZrO3 by neutron powder diffraction , 1976 .

[35]  F. A. Kröger,et al.  Relations between the Concentrations of Imperfections in Crystalline Solids , 1956 .