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首页> 外文会议>Materials Research Society Spring Meeting >Enhanced Thermoelectric Figure-of-merit at Room Temperature in Bulk Bi(Sb)Te(Se) With Grain Size of ～100nm
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Enhanced Thermoelectric Figure-of-merit at Room Temperature in Bulk Bi(Sb)Te(Se) With Grain Size of ～100nm

机译：在室温下增强了散装Bi（SB）TE（SE）的热电数字，具有〜100nm的晶粒尺寸

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摘要

Grain boundaries are known to be able to impede phonon transport in the material. In the thermoelectric application, this phenomenon could help improve the figure-of-merit (ZT) and enhance the thermal to electrical conversion. Bi_2Te_3 based alloys are renowned for their high ZT around room temperature but still need improvements, in both n- and p-type materials, for the resulting power generation devices to be more competitive. To implement high density of grain boundaries into the bulk materials, a bottom-up approach is employed in this work: consolidations of nanocrystalline powders into bulk disks. Nanocrystalline powders are developed by high energy cryogenic mechanical alloying that produces Bi(Sb)Te(Se) alloy powders with grain size in the range of 7 to 14 nm, which is about 25% finer compared to room temperature mechanical alloying. High density of grain boundaries are preserved from the powders to the bulk materials through optimized high pressure hot pressing. The consolidated bulk materials have been characterized by X-ray diffraction and transmission electron microscope for their composition and microstructure. They mainly consist of grains in the scale of 100 nm with some distributions of finer grains in both types of materials. Preliminary transport property measurements show that the thermal conductivity is significantly reduced at and around room temperature: about 0.65 W/m-K for the n-type BiTe(Se) and 0.85 W/m-K for the p-type Bi(Sb)Te, which are attributed to increased phonon scattering provided by the nanostructure and therefore enhanced ZT about 1.35 for the n-type and 1.21 for the p-type are observed. Detailed transport properties, such as the electrical resistivity, Seebeck coefficient and power factor as well as the resulting ZT as a function of temperature will be described.
机译：已知晶界能够阻碍材料中的声子输送。在热电应用中，这种现象可以有助于改善优异（ZT）并增强热转换的热量。基于Bi_2te_3的合金以其高ZT在室温下而闻名，但仍需要改进的N和P型材料，用于所得到的发电装置更具竞争力。为了实现高密度的晶界进入散装材料中，在这项工作中采用自下而上的方法：将纳米晶体粉末固结成散装盘。纳米晶体粉末由高能低温机械合金化开发，生产Bi（Sb）Te（Se）合金粉末，晶粒尺寸在7-14nm的范围内，与室温机械合金化相比，比较细的约25％。通过优化的高压热压将高密度的晶界通过粉末保存到散装材料。 X射线衍射和透射电子显微镜的特征在于它们的组成和微观结构的特征。它们主要由谷物组成100nm，两种类型材料中的一些细粒分布。初步运输性能测量表明，热电导率在室温下显着降低，N型咬合（SE）和0.85W / MK为P型BI（SB）TE的约0.65W / MK，这是归因于纳米结构提供的增加的声子散射，因此观察到N型和1.21用于p型的增强型ZT约1.35。将描述详细的传输属性，例如电阻率，塞贝克系数和功率因数以及作为温度函数的结果ZT。

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