自燃法制备Na掺杂Ca_3Co_4O_9及其热电性能的研究

Self-ignition route to thermoelectric oxides of Na-doped Ca_3Co_4O_9 and their thermoelectric properties

采用简单的自燃法,以去离子水为溶剂,柠檬酸为螯合剂,硝酸盐为原料制备了金属钠掺杂的(NaxCa1-x)3Co4O9热电材料前驱粉。前驱粉经煅烧、球磨、冷压、烧结等工艺获得块体材料。通过X射线衍射,扫描电镜观察等方法对样品的结构与形貌进行了分析表征。在573～1073K温度区间内,测试了材料的电阻率和Seebeck系数。研究表明,试样(x=0.15)在973K时的电阻率可达ρ=5.899mΩ.cm,Seebeck系数S=185μV/K,热电转换功率因子值p=5.802×10-6W/(m.K2)。

Na-doped Ca3Co4O9, （Nax Ca1-x ）3 Co4O9 （x = 0,0.05,0. 1,0. 15,0.2）, thermoelectric powders have been prepared by a simple self-ignition and calcinations route, using the analytic grade Ca（NO3）2 · 3H2O, NaNO3, Co（NO3）2 · 6H2O were as reagents. The stripy samples were obtained by cold compacting and sintering process after the powders ground by ball milling. The microstructures of the ceramic samples were characterized by using X-ray diffraction and scanning electron microscopy. The electrical resistivities and Seebeck coefficients were studied in the temperature range from 573 to 1073K. The results show that the electrical resistivity （ρ）, Seebeck coefficient （S） and power factor （ρ） of Na-doped （0.15） sample are 5. 899mΩ·cm, 185uV/K, and 5.802×10^-6W/（m · K2） at 973K, respectively.