Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (05): 1009-1012.doi: 10.3866/PKU.WHXB20090416

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Preparation and Electrical Transport Properties of Ca2.9M0.1Co4O9 (M=Ag, La, Ba) Oxide Composite System

ZHANG Fei-Feng, ZHANG Jiu-Xing, LU Qing-Mei, ZHANG Xin, LIU Yan-Qin   

  1. Key Laboratory of Advanced Functional Material, Ministry of Education, College of Material Science and Engineering, Beijing University of Technology, Beijing 100124, P. R. China
  • Received:2008-12-02 Revised:2008-12-29 Published:2009-05-04
  • Contact: LU Qing-Mei E-mail:qmlu@bjut.edu.cn

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Abstract:

Bulk samples of a p-type Ca2.9M0.1Co4O9(M=Ag, La, Ba) oxide composite were fabricated by a nitric acid sol-gel and a spark plasma sintering method. X-ray diffraction (XRD) analyses showed a single phase for the samples. The orientation of polycrystalline Ca3Co4O9 could be modified by substituting the Ca. The orientation degree could be improved by decreasing the electronegativity of the substituting atom. Scanning electron microscopy (SEM) analyses showed that these samples were layer-structured and that this layer-structure could be enhanced by decreasing the electronegativity of the substituting atom. Electrical property analyses showed that the reduced resistivity in the measured temperature region could be increased by decreasing the electronegativity of the substituting atom. The conduction path was not disturbed and the transportation mechanism was unchanged for all samples. The Ca2.9Ag0.1Co4O9 sample that was substituted by Ag (the highest electronegativity) exhibited the lowest orientation degree and its resistivity was 6.87 mΩ·cm at 973 K. The Ca2.9Ba0.1Co4O9 sample substituted by Ba (the lowest electronegativity) exhibited the highest orientation degree and its resistivity was 8.22 mΩ·cmat 973 K.

Key words: Ca3Co4O9, Substitution, Electrical transport property