Review of the structural and electrical properties of the (La,Sr)(Co,Fe)O{sub 3} system

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:242491

Anderson, H U; Tai, L W; Chen, C C; Nasrallah, M M; Huebner, W ^[1]

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1. Univ. of Missouri, Rolla, MO (United States). Dept. of Ceramic Engineering

The (La,Sr)(Co,Fe)O{sub 3} LSCF system has been extensively studied because of its potential use as oxygen permeable membranes and cathodes for solid oxide fuel cells. This paper reviews the results of some of these studies and describes the thermochemical and electrical conductivity behavior of this system as functions of composition, temperature (600 to 1,200 C) and oxygen activity (10{sup {minus}19} to 1 atm). The oxygen stoichiometry was measured thermogravimetrically. The results show that at 1,000 C for the composition of La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3} as many as 20% of the oxygen sites can become vacant upon reduction before dissociation occurs. The total electrical conductivity show that at 1000 C in air the electrical conductivity is about 200 S/cm for La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3}, but decreases with reduction as the oxygen vacancies reduce the number of carriers. Upon reduction, these oxides did not dissociate into binary oxides and metal in a simple step, but they formed transient compounds which with further reduction dissociated to La{sub 2}O{sub 3}, SrO, Co, and Fe.

• OSTI ID: 242491
• Report Number(s): CONF-950683--; ISBN 1-56677-095-5
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
CATHODES
CHEMICAL COMPOSITION
COBALT OXIDES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
EXPERIMENTAL DATA
IRON OXIDES
LANTHANUM OXIDES
SOLID ELECTROLYTE FUEL CELLS
SOLID ELECTROLYTES
STRONTIUM OXIDES
THERMAL EXPANSION
X-RAY DIFFRACTION