STRUCTURE AND ELECTRICAL-PROPERTIES OF LA1-XSRXCO1-YFEYO3 .1. THE SYSTEM LA0.8SR0.2CO1-YFEYO3

被引:785
作者
TAI, LW
NASRALLAH, MM
ANDERSON, HU
SPARLIN, DM
SEHLIN, SR
机构
[1] CAIRO UNIV,FAC ENGN,CAIRO,EGYPT
[2] UNIV MISSOURI,DEPT CERAM ENGN,ROLLA,MO 65401
[3] UNIV MISSOURI,DEPT PHYS,ROLLA,MO 65401
关键词
LSCF COMPOSITIONS; MIXED-CONDUCTING OXIDES; PEROVSKITE; SMALL-POLARON CONDUCTOR; SOLID OXIDE FUEL CELL (SOFC);
D O I
10.1016/0167-2738(94)00244-M
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Crystal structure, thermal expansion, thermogravimetry, thermoelectricity, and electrical conductivity of compositions in the system La0.8Sr0.2Co1-yFeyO3 with 0 less than or equal to y less than or equal to 1 were studied as function of Co/Fe ratio and temperature,:in air. The electrical conduction mechanism is attributed to the adiabatic-hopping of p-type small polarons. At high temperatures, oxygen deficiency causes lattice expansion and a reduction in electrical conductivity. The observed temperature dependence of the Seebeck coefficient is attributed to changes in carrier concentration caused by a thermally excited charge disproportionation of Co3+ ions and by the ionic compensation of induced oxygen vacancies. The measured electrical conductivity and Seebeck coefficient as a function of the Co/Fe ratio is interpreted using a two-site hopping and the site-percolation model. It is suggested that a preferential electronic compensation of Fe ions over Co ions may occur in this system.
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页码:259 / 271
页数:13
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