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2004年12月31日

【期刊论文】Sintering and Electronic Conducting Properties of La0.8Ca0.2CrO3 Perovskite-type Complex Oxides Synthesized by Different Methods

徐庆, Q. Xu a, W. F. Guo b, W. Chen c, H. Wang d, D. P. Huang e, B. T. Wang f

,-0001,():

-1年11月30日

摘要

The sintering and electronic conducting properties of La0.8Ca0.2CrO3 synthesized by a glycine-nitrate process (GNP) were investigated in comparison with that synthesized by the conventional solid state reaction (SSR) method. The results demonstrate the advantage of the GNP method in producing La0.8Ca0.2CrO3 ceramic. Compared with the powder synthesized by the SSR method, that synthesized by the GNP method shows a higher sinterability due to its fine morphology. The relative densities of the ceramics made by the GNP and SSR methods attain 96.5% and 96.0% when sintering at 1450℃ and 1550℃, respectively. In the case of similar relative densities, the ceramic made by the GNP method (sintered at 1450℃) exhibits superior electronic conducting properties than that made by the SSR method (sintered at 1550℃). This is attributed to a desired microstructure of the ceramic made by the GNP method.

La0., 8Ca0., 2CrO3,, Perovskite,, Sintering properties,, Electronic conducting properties,, Glycine-nitrate process

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2004年12月31日

【期刊论文】Influence of sintering temperature on microstructure and mixed electronic-ionic conduction properties of perovskite-type La0.6Sr0.4Co0.8Fe0.2O3 ceramics

徐庆, Qing Xu a, b, *, Duan-ping Huang a, Wen Chen a, Joong-hee Lee b, Bok-hee Kim b, Hao Wang a, Run-zhang Yuan a

,-0001,():

-1年11月30日

摘要

Microstructural evolution and mixed electronic-ionic conduction properties of perovskite-type La0.6Sr0.4Co0.8Fe0.2O3 ceramics were investigated in the sintering temperature range 1100-1250℃. The results confirm the crucial role of sintering temperature on microstructure and mixed conduction properties. The improvement of the mixed conduction properties with the increased sintering temperature from 1100℃ to 1200℃ is ascribed to the development of densification. Further increase of the sintering temperature above 1200℃ declined the mixed conduction properties due to the generation of excessive liquid. With respect to the mixed conduction properties, the preferred sintering temperature was ascertained to be 1200℃ for La0.6Sr0.4Co0.8Fe0.2O3 ceramics. The La0.6Sr0.4Co0.8Fe0.2O3 ceramic sintered at 1200℃ exhibited an electrical conductivity of 1.26×103 Ω-1cm-1 and an oxygen ionic conductivity of 3.73×10-2 Ω-1cm-1 at 800℃.

A., Sintering, B., Microstructure, C., Electrical properties, D., Perovskites

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2004年12月31日

【期刊论文】La0.6Sr0.4Co1-yFeyO3钙钛矿复合氧化物的结构与电学性能

徐庆, 徐庆、, 黄端平, 陈文、, 王皓, 袁润章

,-0001,():

-1年11月30日

摘要

采用固相反应法合成出La0.6Sr0.4Co1-yFeyO3体系复合氧化物样品,XRD分析结果证实不同Co/Fe比例的样品中均形成菱形六面体钙钛矿结构,采用固相烧结法制备出致密的La0.6Sr0.4Co1-yFeyO3体系陶瓷。研究结果表明,在室温~900℃温度范围内,La0.6Sr0.4CoO3(y=0)的电导率随温度的增加而单调降低,其它Co/Fe比例样品的电导率随着温度的增加而出现最大值,电导率达到最大值的温度随Co/Fe比例的降低而提高。在低温段,La0.6Sr0.4Co1-yFeyO3体系的导电行为符合小极子导电机制,导电活化能随Co/Fe比例的降低而增加。

钙钛矿结构复合氧化物, La0., 6Sr0., 4Co1-yFeyO3, 电子-离子混合导电, 结构

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2004年12月31日

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

徐庆, 徐庆、, 黄端平, 陈文、, 王皓, 袁润章

,-0001,():

-1年11月30日

摘要

采用甘氨酸-硝酸盐(GNP)法合成出La0.6Sr0.4Co1-yFeyO3(y=0~1.0)体系复合氧化物,对合成产物的结构、烧结性能和导电性能进行表征。研究结果表明,不同Co/Fe比例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℃温度范围内,La0.6Sr0.4CoO3(y=0)的电导率随着温度的提高而单调降低,其它Co/Fe比例样品的电导率随着温度的增加在600℃附近达到最大值。在低温段,La0.6Sr0.4Co1-yFeyO3体系的导电行为符合小极化子导电机制,导电活化能随Co/Fe比例的降低而增大。与常规固相合成法相比,甘氨酸-硝酸盐法制备的La0.6Sr0.4Co1-yFeyO3具有更高的烧结活性和电导率。

La0., 6Sr0., 4Co1-yFeyO3, 钙钛矿复合氧化物, 甘氨酸-硝酸盐法, 电子-离子混合导电

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2004年12月31日

【期刊论文】X-ray photoelectron spectroscopy investigation on chemical states of oxygen on surfaces of mixed electronic-ionic conducting La0.6Sr0.4Co1-yFeyO3 ceramics

徐庆, Qing Xu*, Duan-ping Huang, Wen Chen, Hao Wang, Bi-tao Wang, Run-zhang Yuan

,-0001,():

-1年11月30日

摘要

The chemical state of oxygen on the surfaces of mixed electronic-ionic conducting La0.6Sr0.4Co1-yFeyO3 ceramics was characterized by X-ray photoelectron spectroscopy (XPS). It was ascertained that there are five different kinds of oxygen on the ceramic surfaces, including lattice oxygen (OL), chemisorbed oxygen (Oc) in the forms of O-2, O-1 and O-1 2, and oxygen in hydroxyl environment (OH). The concentration of OC+OH relative to total detected oxygen enhanced with the increase of Co/Fe ratio. In order to examine the relation between the chemical states of oxygen on the surfaces and the electrical nature of the ceramics, the mixed electronic-ionic conducting properties were investigated. At an identical measuring temperature, the electronic conductivity and ionic conductivity of La0.6Sr0.4Co1-yFeyO3 ceramics tended to rise with the increase of Co/Fe ratio. It was considered that the mixed electronic-ionic conducting properties are responsible for the complex chemical states of oxygen on the ceramic surfaces.

La0., 6Sr0., 4Co1-yFeyO3, Perovskite-type ceramics, XPS, Chemical state, Oxygen, Mixed electronic-ionic conducting properties

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  • 徐庆 邀请

    武汉理工大学,湖北

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