通过直流四端法研究了钙钛矿型混合导体La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) 和La0.6Sr0.4Co0.2Fe0.8O3–δ- Ce0.9Gd0.1O1.95(LSCF-GDC) 复合材料的高温电学性质. 通过电导率测试得出单相LSCF和LSCF-GDC的小极化子导电活化能分别为Ea1=9.72kJ/mol和 Ea2=10.64kJ/mol. 突然改变氧分压条件进行电导弛豫测试, 进而研究了二者的氧表面交换性质. 测定了温度范围在600~800℃、氧分压在21~34kPa之间变化时两种样品的表面交换系数为kchem为2.87×10-6~6.91×10-6cm/s. 讨论认为GDC对氧表面交换过程的催化作用与引入GDC对材料微结构的影响共同促进了复合材料中的氧输运过程. 根据两种样品氧表面交换系数和温度的关系估算了氧表面交换过程活化能.
王严东1
,
2
,
吕 喆2
,
魏 波2
. La0.6Sr0.4Co0.2Fe0.8O3–δ-Ce0.9Gd0.1O1.95高温电导弛豫的研究[J]. 无机材料学报, 2010
, 25(6)
: 635
-640
.
DOI: 10.3724/SP.J.1077.2010.00635
High temperature electrical conductivity of perovskite-type mixed with ionic-electronic conductor La0.6Sr0.4Co0.2Fe0.8O3–δ (LSCF) and La0.6Sr0.4Co0.2Fe0.8O3–δ- Ce0.9Gd0.1O1.95(LSCF-GDC) composite material were studied by the DC four-terminal technique. The activation energies of pure LSCF and LSCF-GDC composite for small polaron conduction were Ea1=9.72kJ/mol and Ea2=10.64kJ/mol, respectively. Through electrical conductivity relaxation method, i.e. a continuously resistance measurement during the sudden change oxygen under partial pressure and the surface exchange property of the two samples were also investigated. In the temperature range from 600℃ to 800℃ and the oxygen partial pressure range from 21kPa to 34kPa, the oxygen surface exchange coefficients (kchem) were determined as 2.87×10-6-6.91×10-6cm/s. It is the catalysis effects of GDC on oxygen surface exchange process and the microstructure effect of introducing GDC that promoted the oxygen transport process of composite materials jointly. Based on the relationship of kchem and temperature, the activation energies for surface exchange process was also estimated.
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