制备方法对Pr_(0．6)Sr_(0．4)FeO_(3-δ)结构与性能的影响

EFFECT OF PREPARATION METHODS ON STRUCTURE AND PROPERTIES OF Pr_(0．6)Sr_(0．4)FeO_(3-δ)

采用甘氨酸-硝酸盐、Pechini、柠檬酸-硝酸盐以及尿素-硝酸盐等4种不同的湿化学方法,制备了Pr0.6Sr0.4FeO3-δ复合氧化物粉体。用X射线衍射分析了材料中钙钛矿物相的形成过程及其与中温电解质的化学相容性。用扫描电镜研究了样品的微结构。结果表明:不同方法得到的素坯经 1000℃煅烧2 h即形成钙钛矿结构的固溶体。Pechini法制备的非晶产物煅烧后钙钛矿物相的纯度最高。素坯经1200℃煅烧2 h,所得陶瓷体的总气孔率均为43％-49％:体积密度以柠檬酸-硝酸盐法粉体的样品最高,甘氨酸-硝酸盐法最低。在室温到800℃的温度范围内,Peebini法制备的陶瓷体的热膨胀系数为12．15×10-6/K,与电解质Sm0.2(2e0.8O1.9(SDC)及La0.8Sr0．2Ga0．8Mg0.2O3-δ(LSGM)的数值一致。X射线衍射揭示产物与中温电解质SDC及LSGM 具有良好的化学相容性。

Pr0.6Sr0.4FeO3-δ（PSF） composite-oxide powders with a perovskite-type structure were synthesized using four types of humid-chemical methods： the glycine-nitrate process （GNP）, Pechini process, citric acid-nitrate process （CNP） and urea-nitrate process （UNP）. The formation process of the perovskite phase in PSF and the chemical compatibility between that with electrolytes Sm0.2Ce0.8O1.9（SDC）and/or La0.8Sr0.2Ga0.8Mg0.2O3-δ（LSGM）were detected by X-ray diffraction. The microstructures of the ceramics were analyzed by scanning electron microscope. The results show that a solid solution with perovskite phase is formed for all raw shapes after calcination at 1 000℃for 2 h, and the perovskite phase with the highest purity is obtained after sintering and using the amorphous powder products synthesized by the Pechini method. The total porosity of ceramics is 43 %-49% after sintering at 1 200℃ for 2 h, The relative density of ceramics prepared by CNP is the highest, while that of the ceramic sample prepared by GNP is the lowest. From room temperature to 800℃, the thermal expansion coefficient of the ceramics sintered at 1 200℃for 10 h with the powder by the Pechini method is 12.15×10^-6/K, which is consistent with that of the SDC and/or LSGM electrolyte. The chemical compatibility between PSF cathode materials and SDC and LSGM is satisfactory.