摘要
采用甘氨酸 -硝酸盐 ( GNP)法合成出 La0 .6Sr0 .4Co1-y Fey O3 ( 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～ 90 0℃范围内 ,La0 .6Sr0 .4Co O3 ( 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 60 0℃附近时达到最大值 .在低温段 ,La0 .6Sr0 .4Co1-y Fey O3 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 La0 .6Sr0 .4Co1-y Fey O3 具有更高的烧结活性和电导率 .
La 0.6Sr 0.4Co 1-yFe yO 3 (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 0.4CoO 3 (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 3.22×10 2-1.5×10 3 S/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 yO 3 synthesized 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 yO 3 oxides 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.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第12期2271-2274,共4页
Chemical Journal of Chinese Universities
基金
湖北省自然科学基金 (批准号 :2 0 0 1ABB0 75 )
武汉市晨光计划 (批准号 :2 0 0 15 0 0 5 0 3 1)
材料复合新技术国家重点实验室重点基金资助
