La_(0.5)RE_(0.3)Sr_(0.2)FeO_(3-δ)(RE=Nd、Ce、Sm)体系双稀土阴极材料的制备与电性能

Synthesis and Properties of La_(0.5)RE_(0.3)Sr_(0.2)FeO_(3-δ)(RE=Nd, Ce, Sm) System with Two Rare Earths for Cathodes

采用甘氨酸-硝酸盐法(GNP)合成了La0.5RE0.3Sr0.2FeO3-δ(RE=Nd、Ce、Sm)系列复合氧化物粉体.用X射线衍射(XRD)和TG-DSC分析了样品钙钛矿物相的形成过程,用Archimedes排水法测量体积密度并计算烧结样品的相对密度,用四端子技术测量电导率.结果显示,掺Nd的样品1200℃烧结2h成为单一立方钙钛矿结构,掺Ce样品有明显的CeO2立方相析出,掺Sm样品主相为钙钛矿结构伴有微弱的杂峰.1250℃烧结2h的La0.5Nd0.3Sr0.2FeO3-δ在600℃时电导率高达100S·cm-1以上,明显高于La0.5Ce0.3Sr0.2FeO3-δ及La0.5Sm0.3Sr0.2FeO3-δ样品的电导率,预示着La0.5Nd0.3Sr0.2FeO3-δ可能是一种良好的中温固体氧化物燃料电池(SOFC)阴极材料.

Two rare earths composite oxides of La0.5RE0.3Sr0.2FeO3-δ（RE=Nd、Ce、Sm） with A-site doped Sra^2＋ samples were synthesized by Glycine-Nitrate processes （GNP）. The formation process of the perovskite structure was analyzed by means of X-ray powder diffraction and TG-DSC. The relative density of the ceramics was measured by Archimedes method, and the electrical conductivity of the samples was studied by four-probe technique. The results show that the sample for RE=Nd presents a single perovskite-type phase with a cubic symmetry after sintering at 1200 ℃ for 2 h, while the samples with Ce doped showed a separated cubic phase of CeO2, and the specimen doped with Sm is a cubic perovskite-type phase accompanied by some faint impure peaks. The electrical conductivity of La0.5RE0.3Sr0.2FeO3-δ（RE=Nd、Ce、Sm）） sample obtained from being sintered at 1250 ℃ for 2 h was over 100 S· cm^-1, significantly higher than that of the La0.5RE0.3Sr0.2FeO3-δ（RE=Nd、Ce、Sm） and La0.5RE0.3Sr0.2FeO3-δ（RE=Nd、Ce、Sm） at the same conditions. The results indicate that La0.5RE0.3Sr0.2FeO3-δ may be a suitable cathode material for intermediate temperature SOFC.