K、Al共掺杂Bi_2 Te_(2.7) Se_(0.3)热电材料的制备及性能研究

Preparation and thermoelectric properties of K and Al co-doped Bi_2 Te_(2. 7) Se_(0. 3)

采用真空熔炼和热压烧结技术制备了 K 和Al 共掺杂 Bi2 Te2．7 Se0．3热电材料.利用 X 射线衍射（XRD）、扫描电子显微镜（SEM）对样品的物相结构和表面形貌进行了表征. XRD 分析结果表明,K0．04 Bi1．96-x Alx Te2．7 Se0．3块体材料的 XRD 图谱与 Bi2 Te2．7 Se0．3的 XRD 图谱对应一致,SEM 形貌表明材料组织致密且有层状结构特征.K0．04 Bi1．92-Al0．04 Te2．7 Se0．3合金提高了材料的 Seebeck 系数,K0．04 Bi1．88 Al0．08 Te2．7 Se0．3和 K0．04 Bi1．84 Al0．12 Te2．7 Se0．3大幅度提高了材料的电导率,通过 K 和 Al 部分替代 Bi,使材料的热导率有不同程度的减小,在300~500 K 温度范围内,K 和 Al共掺杂均较大幅度地提高了 Bi2 Te2．7 Se0．3的热电优值.

K and Al co-doped Bi2 Te2 .7 Se0.3 thermoelectric materials were synthesized by vacuum melting and hot pressing method.Phase structure and surface morphology were characterized via X-ray diffraction （XRD）,scan-ning electron microscope （SEM）.XRD results indicate that all the characteristic peaks of the bulk K0.04 Bi1 .9 6 -x Alx Te2 .7 Se0.3 can be indexed into rhombohedral Bi2 Te2 .7 Se0.3 .SEM analysis shows that the bulk samples are compact with the laminated structure.Seebeck coefficients of K0.04 Bi1 .92 Al0.04 Te2 .7 Se0.3 alloy are improved.K0.04 Bi1 .88 Al0.08 Te2 .7 Se0.3 and K0.04 Bi1 .84 Al0.1 2 Te2 .7 Se0.3 samples results in substantial increase in electrical conductivity. Thermal conductivity can be reduced by partial substituting Bi with K and Al.K and Al co-doping can effective-ly enhance the thermoelectric figure of merit of Bi2 Te2 .7 Se0.3 alloy from 300 to 500 K.