采用柠檬酸-硝酸盐法合成了Pr0.6-xNdxSr0.4FeO3-δ(x=0.0~0.6)系列钙钛矿型复合氧化物粉体, 用
XRD、FT-IR、TD-DTA、SEM等对产物的形成过程、物性及微结构进行了表征. 结果表明, 所合成的系列样品1200C煅烧2h即形成立方钙钛矿结构
的单相固溶体. 用直流四端子法测量了烧结陶瓷体在中温(450~800℃)范围内的电导率, A位单一稀土元素的样品(x=0.0、0.6)及以Pr(x=0.1)或
Nd(x=0.5)为主的稀土复合氧化物, 其电导率均在150S cm-1以上,明显高于双稀土样品(x=0.2、0.3、0.4)的数值( σ=45~80S cm-1); x=0.2、0.3
、0.4三个样品电导率较低的原因, 与它们在同样烧结制度下的致密度低密切相关.该系列样品的电导率在650~700℃附近出现最大值, 低温段的导电行为符合小极化子导电机制.
Pr0.6-xNdxSr0.4FeO3-δ(x=0.0~0.6)samples were synthesized by the citrate-nitrate method. The formation process of the perovskite-type phase and the microstructure of the samples were characterized by XRD, FT-IR, TG-DTA, and SEM. The results revealed that all the samples calcined at 1200℃ for 2h were single-phase solid solutions with cubic symmetry. The electrical conductivity of sintered ceramics at 450~800C were measured by four-probe technique. The results show that the specimens with single rare earth and the compounds with Pr or Nd as leading element at A-site have excellent electrical conductivity, the data are over 150S cm-1, clearly higher than that of two-rare earths specimens. The reason of decreasing electrical conductivity for 0.2≤x≤0.4 is correlated with lower relative density at the same sintering conditions. The maximum value of electrical conductivity for all samples occurred at about 600~700℃, and the electrical conductivity certified that the hopping of small polaron is the dominating mechanism below 650℃.
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