热压烧结P型碲化铋基热电材料的显微组织与性能

Microstructure and properties of hot pressed P-type bismuth tellurium based thermoelectric materials

为克服目前市售单晶产品加工性能差、取向性高等问题,以高纯单质Te、Bi和Sb为原料,采用熔炼-冷淬-粉碎-热压工艺制备P型碲化铋基热电材料;用氧氮分析仪、粒度分析仪对热压烧结前粉料的氧含量和粒度进行了测定,用扫描电镜、X射线衍射仪对烧结块体沿不同方向的微观形貌、物相结构进行了表征。不同方向的热电性能测试结果显示,热压工艺制备的P型碲化铋基热电材料在不同方向上的塞贝克系数和ZT值基本相同,但电阻率和热导率有不同程度的取向;与市售区熔单晶相比,取向度明显降低,最终样品的相对密度高达99%,且最高ZT值为1.02。该热压烧结工艺的生产设备简单、生产成本低、工作效率高,适合推广至工业化规模生产。

In order to overcome the poor processing performance and high orientation of the single crystal prod-ucts,bismuth telluride based P-type thermoelectric materials were prepared by melting-quenching-crushing-hot pressing process with high-purity elemental Te,Bi and Sb as raw materials. The oxygen content and particle size of the powder before sintering were determined by using the oxygen and nitrogen analyzer,particle size analyzer. The phase structure and microstructure along the two different directions of the sintered body were analyzed by X-ray diffraction and scanning electron microscope. The thermoelectric performances in different directions show that both the electrical and thermal conductivities show anisotropy to a certain extent,while the Seebeck coeffi-cient and the ZT value are almost isotropic. Compared with the current commercially available single crystal prod-ucts,the orientation degree of samples decreases obviously,and the relative density of the final sample reaches up to 99%with a peak ZT value of 1.02. The hot pressing process has a lot of advantages,such as simple equipment, low cost and high efficiency,making it suitable for promotion to industrial scale production.