La0.6Sr0.4Co1-yFeyO3钙钛矿复合氧化物的GNP法合成与导电性能

采用甘氨酸-硝酸盐(GNP)法合成出La_0.6Sr_0.4Co_1-yFe_yO₃(y=0～1.0)体系复合氧化物,对合成产物的结构、烧结性能和导电性进行了表征.研究结果表明,不同n(Co)/n(Fe)比的合成粉料中形成菱形六面体钙钛矿结构,合成粉料的颗粒细小均匀.在室温～900℃范围内,La_0.6Sr_0.4CoO₃(y=0)的电导率随温度的升高而单调降低,其它n(Co)/n(Fe)比的样品电导率随着温度升高到600℃附近时达到最大值.在低温段,La_0.6Sr_0.4Co_1-yFe_yO₃体系的导电行为符合小极化子导电机制,导电活化能随n(Co)/n(Fe)比的降低而增大.与常规固相合成法相比,甘氨酸-硝酸盐法制备的La_0.6Sr_0.4Co_1-yFe_yO₃具有更高的烧结活性和电导率.

GNP Synthesis and Electrical Conduction Properties of La0.6Sr0.4Co1-yFeyO3 Perovskite-type Oxides

La_0.6Sr_0.4Co_1-yFe_yO₃(y=0-1.0) fine powders were synthesized by a Glycine-Nitrate Process (GNP) method, and a perovskite-type structure with rhombohedral symmetry was certified for the powders by XRD. The electrical conductivity of La_0.6Sr_0.4CoO₃(y=0) decreased monotonously with the increase of temperature in the range from room temperature to 900℃, while the electrical conductivities of it in other n(Co)/n(Fe) ratios increased with increasting temperature and reached the maximums of 3.22×10²-1.5×10³S/cm near 600 ℃ and then decreased. The hopping of small polarons is the dominating mechanism for the electrical conduction at low temperatures. The activation energy of the small polarons hopping increased from 3.378 to 17.471 kJ/mol with the decrease of n(Co)/n(Fe) ratio. Compared with the La_0.6Sr_0.4Co_1-yFe_yO₃synthesized by a conventional solid state reaction method, those synthesized by the GNP method exhibit a higher sintering activity and electrical conductivities. The differences in the temperature of electrical conductivity maximum and activation energy between the La_0.6Sr_0.4Co_1-yFe_yO₃oxides with an identical composition synthesized by the GNP method and solid state synthesis method, respectively, are attributed to the influences of stoichiometry and microstructure on electrical transportation process.