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摘要:
Double-substituted BaxAgyCa3-x-yCo4O9 bulks were fabricated by nitric acid sol-gel and spark plasma sintering, and the phase composition, orientation, texture and electrical transport properties of the bulks were investigated by means of X-ray diffraction, scanning electron microscope and electrical resisitivity measurement. The result shows that silver which does not belong to the stoichiometric compounds BaxAgyCa2.8Co4O9 is distributed in the matrix. The degree of orientation increases with increasing ratio of Ba to Ag for the double-substituted bulk. The orientation of BaxAgyCa2.8Co4O9 (y > 0) bulks is prominently lower than that of Ca3Co4O9 and the orientation of Ba0.2Ca2.8Co4O9 bulk is higher than that of Ca3Co4O9 bulk. The electrical transport mechanism of the bulk with x = y = 0. 1 is changed slightly. The Ba0.1Ag0.1Ca2.8Co4O9 bulk exhibits simultaneously lowered orientation and moderately low resistivity and the resistivity reaches 7.3 m Omega(.)cm at 973 K. The Ag0.2Ca2.8Co4O9 bulk exhibits lowest orientation and lowest resistivity, reaching 6.3 m Omega(.)cm at 973 K.
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