以碳酸盐和氧化物为原料,通过凝胶浇注法制得了Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ)(SSCF, x=0～1.0)粉体,对不同温度煅烧所得粉体的相组成和微观形貌进行了测定.制备的Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ)粉体模压成形后烧结得到SSCF烧结体.测定了烧结体的密度和孔隙率并对烧结体的微观结构进行了观测,用直流四端子法测定了烧结样品的电导率并对其热膨胀系数及电化学性能等进行了测定.结果表明:干凝胶在1000 ℃煅烧可以得到粒度均匀细小的SSCF粉体,其晶体结构随Fe含量发生变化;一定温度烧结的Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ)材料具有多孔结构,随烧结温度的增加,烧结体的密度增大,孔隙率减小;Fe的掺杂降低了Sm_(0.5)Sr_(0.5)CoO_(3-δ)材料的热膨胀系数,Sm_(0.5)Sr_(0.5)Co_(0.2)Fe_(0.8)O_(3-δ)材料在800 ℃时的热膨胀系数为16.4×10~(-6) K~(-1);SSCF材料的电导率随Fe含量的增加而减小,但在500～800 ℃,其电导率均大于100 S·cm~(-1).此外,Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ)材料均表现出良好的催化活性.
Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ)(SSCF,x=0～1.0)powders were prepared by a gel-casting method using corresponding carbonates and oxides as raw materials. Phase composition and morphology of the obtained powders was investigated. Density and porosity of the sintered SSCF samples were measured by the Archimedes method. The microstructure was observed by scanning electron microscope (SEM), and the electrical conductivity was tested by the four-probe method. Thermal expansion coefficient (TEC) and electrochemical performance of the SSCF materials were also studied. The results showed that superfine and well-dispersed SSCF powders with perovskite structure are obtained when the dried gels are calcined at temperature above 1000 ℃.The iron dosage and temperature have an obvious influence on the phase formation, the density and the pore characteristics of the SSCF samples. The doping of Fe effectively lowers the TEC of the Sm_(0.5)Sr_(0.5)CoO_(3-δ) materials. Electrical conductivity of the SSCF samples decreases with iron doping but all is above 100 S·cm~(-1) at 500～800 ℃. Furthermore, the Sm_(0.5)Sr_(0.5)Co_(1-x)Fe_xO_(3-δ) samples show high oxygen catalytic activities.
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