| La1-xSrxFeO3-δ系钙钛矿材料的表征和性能 |
| Characterization and Properties of La1-xSrxFeO3-δ with Perovskite-type Structure |
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| 摘要: 采用甘氨酸-硝酸盐(GNP)法合成了中温固体氧化物燃料电池阴极材料La1-xSrxFeO3-δ(x=0.0~0.6)系列粉体。用FTIR、TG-DTA、XRD等对产物形成过程及结晶学特征进行了研究，考察了合成样品与Sm0.2Ce0.8O1.9(SDC)的化学相容性；利用碘滴定法测定了该系列产物中Fe元素的平均表观化合价和氧的非化学计量值。结果表明，所合成的系列样品均形成具有ABO3型结构的钙钛矿固溶体。随A位取代Sr含量的增加，IR谱图上560
cm-1附近B-O键伸缩振动的红外吸收峰蓝移，意味着钙钛矿产物中Fe-O键的共价性成分增强。实验还发现，Fe元素的平均化合价先随样品中Sr含量的增加而升高，并以La0.6Sr0.4FeO3-δ样品达最高，而后降低；样品中氧的非化学计量值则随掺Sr量的增加单调增大。四探针法电导测量结果表明，在x≤0.4时，La1-xSrxFeO3-δ系列陶瓷烧结体在中温(450~800 ℃)区的电导率，随Sr掺入量的增大而增大，La0.6Sr0.4FeO3-δ样品的电导率最高，进一步增大Sr含量导电性能变差。在低温段，样品的导电行为符合小极化子导电机制。该系列材料与SDC电解质材料具有良好的化学相容性。 |
| 关键词: La1-xSrxFeO3-δ 非化学计量 阴极材料 电导率 相容性 |
| 基金项目: |
| Abstract: The powders of La1-xSrxFeO3-δ (x=0.0~0.6) as fuel cells cathode materials were prepared by glycine-nitrate process (GNP). The formation of the perovskite structure and features of the crystallite for all samples have been characterized by means of FTIR, TG-DTA and XRD techniques. The chemical compatibility of the samples with
Sm0.2Ce0.8O1.9 (SDC) has been investigated as well. The iodometric titration was used to determine the oxidation state of Fe ions and the oxygen nonstoichiometry in
La1-xSrxFeO3-δ. It has been found that all samples calcined at 1 100 ℃ are perovskite structure with ABO3 model. When Sr content at A-site was increased, blue shift of the IR absorption peak of B-O stretching vibration frequence was detected, which indicated that the proportion of covalent bond of the B-O was enhanced. The Fe mean valence value increased with the Sr-doping content, went through a maximum at x=0.4 and decreased with higher Sr substitution, whereas the oxygen nonstoichiometry of all compositions increased monotonously. With less than 40% of strontium addition, the electrical conductivity measured by four probe method increased as Sr content and reached maximal value at x=0.4. Further increase in doping resulted in deterioration of conducting properties. The changes of conductivity with temperature below 700 ℃ were in accordance with the conduction mechanism of small polarons. It is noticeable that all the samples represent good chemical compatibility with SDC at 1 200 ℃ for 12 h. |
| Keywords: La1-xSrxFeO3-δ nonstoichiometry cathode materials electrical conductivity compatibility |
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| 陈永红,魏亦军,刘杏芹,孟广耀.La1-xSrxFeO3-δ系钙钛矿材料的表征和性能[J].无机化学学报,2006,22(1):31-36. |
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