Method for preparing polycrystalline textured thermoelectric material from single-crystal bismuth sulfide precursor powder

Abstract

The invention belongs to the technical field of energy materials, in particular relates to a method for preparing polycrystalline textured thermoelectric materials from single-crystal bismuth sulfide precursor powder. Specifically, the method comprises the following steps of: selecting uniformly-orientated single-crystal bismuth sulfide [Bi2S(3-x), 0<=x<=0.5] powder (including nanoflakes, nanotubes and nanowires) as precursor powder; performing rapid sintering under increased pressure by using a spark plasma sintering technique so that the single-crystal powder trends to be arranged in the direction perpendicular to the pressure and freeze to form highly-textured dense polycrystalline bulk thermoelectric materials; and controlling the texture degree, the crystal grain degree and the density of the bulk materials by adjusting the applied pressure, the sintering temperature and the heat retention time. Owing to the texture, the polycrystalline materials show strong anisotropy, so that the power transmission performance is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of energy materials, and in particular relates to a method for preparing polycrystalline textured thermoelectric materials with single crystal precursor powder, which has a simple and fast preparation process and is beneficial to improving the performance of polycrystalline bulk thermoelectric materials. Background technique [0002] In recent years, environmental and energy issues have attracted more and more attention from human society. As thermoelectric materials that can directly realize the mutual conversion of heat energy and electric energy, which is conducive to improving the comprehensive utilization rate of energy, and are non-polluting and zero-emission, they have also attracted increasing attention. Thermoelectric devices with thermoelectric materials as the core module have the advantages of light structure, small size, long life, and mild working environment, and have broad application prospect...

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Problems solved by technology

Our research group synthesized non-stoichiometric Bi by ball milling 2 S 3 Nano powder (patent number: ZL200810106199.0), after sintering the nano powder into a block by spark plasma sintering technology, Bi with texture was prepared by secondary electric plasma sintering hot forging method 2 S 2.90 The thermoelectric properties of bulk thermoelectric materials (publication number: CN101358313B) have been improved compared with samples without hot forging, but the texture phenomenon is not obvious, and the texture degree is also very limited [L.D. Zhao, B.P. Zhang, W.S. Liu, H.L. Zhang, J.F. Li. J. Solid State Chem. 181 (2008), 3278]

[0005] The hot forging method requires at least two or more spark plasma sinterings, and each sintering requires the mold to be replaced with a mold with a larger size than the previous one. There is internal stress in the fired sample, and the highest texture degree that can be achieved is limited. Longer heat treatment time will also cause the grain size of the textured sample to grow, which is not conducive to reducing the thermal conductivity of the material.

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