Electrical conduction properties of Sr-doped LaPO4 and CePO 4 under oxidizing and Reducing conditions

Naoto Kitamura, Koji Amezawa, Yoichi Tomii, Teiichi Hanada, Naoichi Yamamoto, Takahisa Omata, Shinya Otsuka-Yao-Matsuo

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54 Citations (Scopus)

Abstract

Electrical conduction properties of Sr-doped LaPO4 and Sr-doped CePO4 under H2O/O2 and H2O/H 2 conditions were investigated with conductivity measurements. Conductivities of 1 mol % Sr-doped LaPO4 were 10.2 - 103.5 S cm-1 at 500-925°C under wet reducing conditions and were close to those under wet oxidizing conditions. It was found from the H/D isotope effect on conductivity that the material showed dominant protonic conduction under wet reducing conditions. As for 1 mol % Sr-doped CePO4, conductivities were 102.8-102.0 S cm-1 at 500-925°C under wet oxidizing conditions and much higher than those of 1 mol % Sr-doped LaPO4 under the same conditions. Such high conductivities of Sr-doped CePO4 seemed attributable to electronic conduction due to partial oxidation of Ce3+ to Ce 4+ caused by substituting Sr2+ for Ce3+. Under wet reducing conditions, however, conductivities of the material decreased to 10-5.2-10-3.43.4 S cm-1 at 500-925°C, which was almost comparable with those of 1 mol % Sr-doped LaPO4. It was concluded that Sr-doped CePO4 showed mixed protonic and p-type electronic conductions under wet reducing conditions. Based on the results of conductivity measurements, defect structures in Sr-doped LaPO4 and CePO4 under wet oxidizing and reducing conditions are discussed.

Original languageEnglish
Pages (from-to)A658-A663
JournalJournal of the Electrochemical Society
Volume152
Issue number4
DOIs
Publication statusPublished - 2005
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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