Na_xCo_2O_4基复合材料的制备及其热电性能

Preparation of Na_x Co_2 O_4 Based Composite and Its Thermoelectric Properties

采用固相反应法制备出NaxCo2O4(x=0.9,1.1,1.3)多晶氧化物,采用水热法制备出(Bi0.1Sb0.9)2Te3单相粉末材料,再用球磨法将二者均匀混合获得了复合材料(Bi0.1Sb0.9)2Te3/NaxCo2O4。在5～300K的温度范围内,利用综合物性测试系统(PPMS)对热压复合材料的热电性能进行测量与评价。实验结果表明复合材料的热导率显著降低,同时电导率增大,与NaxCo2O4相比,复合材料的热电性能获得了显著提高。在室温下,复合材料的热电优值ZT约为3.5×10-4。热电性能的改善源于复合材料界面的声子散射的增强。

Polycrystalline oxides NaxCo204（x：0.7, 0.9, 1.1, 1.3） were prepared by using solid state reaction method, and a single phase （Bi01Sb0.9）2 Te3 alloy powder was synthesized by hydrothermal method. Then, （Bi0.1 Sb0.9）z Te3/Nax Coz 04 composite was produced through mixing and ball milling of the two materials. The thermoelectric properties of hot pressed pellets of the composite were measured from 5 to 300 K by using physical properties measurement system （PPMS）. At room temperature, the thermoelectric figure-of-merit （ZT） of the composite is about 3.5 × 10-4, which is relatively high comparing to Na×Co2 04. It is considered that the improved thermoelectric performance of the composite mainly originates from the reduced thermal conductivity due to an enhanced phonon scattering at interfaces.