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Low Temperature Aqueous Synthesis of Bi2Te3 Based Thermoelectric Materials

Author: WangZuo
Tutor: ZhuDongSheng
School: South China University of Technology
Course: Chemical Engineering
Keywords: Thermoelectric materials Bi2Te3 Low temperature wet chemical method
CLC: TB34
Type: Master's thesis
Year: 2011
Downloads: 65
Quote: 0
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Abstract


Thermoelectric materials is a new energy materials achieve the direct conversion of heat and electricity in a wide range of applications in the field of thermoelectric cooling and thermoelectric power generation. Room temperature under the best performance thermoelectric materials thermoelectric materials the Bi 2 Te 3 base. How to improve the thermoelectric properties of the material is the current hot spots, nano can significantly reduce the thermal conductivity of the material, thereby enhancing the thermoelectric properties of the material. Wet chemical method has been widely used as an effective synthesis of nano thermoelectric materials, process equipment, low reaction temperature, low energy consumption, high yield, etc.. In this paper, a low-temperature wet chemical method, combined with the vacuum hot pressing sintering technology, synthesized Bi 2 Te 3 -based thermoelectric materials. XRD, SEM, EDS and other means of testing the material synthesized product analysis and morphology analysis, exploration Bi 2 Te 3 synthesis process related chemical reactions mechanism. In this paper, to do the following research: (1) Bi 2 Te 3 based thermoelectric materials prepared by low temperature wet chemical, different reaction conditions such as the pH of the solution value, reaction temperature, reaction time on the product composition and morphology of the best process parameters as pH = 12.6, the reaction temperature of 70 ° C, the reaction time of 48 h. (2) the initial exploration Bi 2 Te 3 synthesis reaction mechanism, think both the Bi 3 ions and Te 2 - bonding between the ions, and also the reaction between the Bi atoms and activity Te atoms. (3) Bi nanoscale dimensions 2 Te 3 added sodium dodecylbenzenesulfonate (SDBS), cetyltrimethylammonium bromide ammonium (CTAB), polyvinyl pyrrolidone (PVP) and other additives, the additives on the phase composition and morphology of the study results show that: the additives do not affect Bi 2 Te < sub> 3 synthesis, but affect the morphology and size of the product. No additives, the product of serious agglomeration agglomerated particles of 500 nm; Add CTAB of SDBS, the particle size is reduced to 400 nm dispersion effect has been improved; Add PVP, particle size reduction as small as 200 nm, the dispersion effect has been improved. (4) to study the complexing agent is ethylenediamine tetraacetic acid (EDTA) on the phase composition and morphology of the results showed that: EDTA was added, the synthesized product less impurity phase. Plus EDTA is not the product of serious agglomeration agglomerated particles of 500 nm; addition of EDTA, the particle size is reduced to 200 nm, and the dispersion effect improvements to. (5) The use of low-temperature wet chemical method, BiCl 3 and Te powder raw materials, respectively, in dimethylformamide (DMF), deionized water, ethanol as the reaction medium Synthesis of Bi 2 Te 3 , the research on the morphology and phase composition of the reaction medium. The results show that: the aqueous solvent, the particle size of the synthesized product is greater than the particle size of the synthesized product in anhydrous ethanol and DMF solvent, deionized water as a solvent when the highest purity of the product.

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