Chem. J. Chinese Universities ›› 2017, Vol. 38 ›› Issue (8): 1309.doi: 10.7503/cjcu20170244

• Articles: Inorganic Chemistry • Previous Articles     Next Articles

Effects of Ag+, Sr2+, Yb3+ Dual-doping on Thermoelectric Properties of Ca3Co4O9-δ

YANG Tao, CHENG Tiexin, ZHOU Guangdong   

  1. College of Chemistry, Jilin University, Changchun 130021, China
  • Received:2017-04-19 Revised:2017-07-14 Online:2017-08-10 Published:2017-07-14
  • Supported by:

    Supported by the Petroleum Production Engineering Institute Fund of Daqing Oil Field Limited Company, China(No. DQYT-1204003-2015-JS-824).

Abstract:

A series of ceramic materials, Ca3-x-yAgxSryCo4O9-δ, Ca3-x-zAgxYbzCo4O9-δ and Ca3-y-zSryYbzCo4O9-δ(x, y, z=0.1, 0.15, 0.2) which worked from 300 K to 870 K with excellent thermoelectric properties, was prepared by sol-gel and cold-pressing method. The XRD, IR and SEM results reveal that the prepared samples are uniform crystal particles with high purity. Ag+, Sr2+ and Yb3+ ions have replaced the position of Ca2+ ions and they are dissolved in the crystal, which changes the cell volume of the dual-doping materials but does not change the crystal symmetric structure. The characterization results of resistivity and Seebeck coefficient reveal that the concentration of carrier is optimized by dual doping, accordingly the resistivity decreases continuously with the doped different materials and the value of Seebeck coefficient increases continuously with the doped different materials. It can be concluded from the calculations that the electron effective mass contributes to the increase of Seebeck coefficient. The characterization results of thermal conductivity indicate that the thermal conductivity of dual doped samples decreases with the increase of temperature, and the phonon thermal conductivity still contributes more in the prepared system, which is consistent with the results of Ag+, Sr2+, Yb3+ single doped Ca3Co4O9-δ samples. The figure of metrt ZT of Ca2.7Ag0.2Yb0.1Co4O9-δ exceeds 0.18 at 870 K.

Key words: Dual doping, Sol-gel process, Thermoelectric property, Ceramics

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