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Research On Preparation And Thermoelectric Properties Of Bi 2 Te 3 And Its Composition With Polyaniline

Posted on:2011-03-14Degree:MasterType:Thesis
Country:ChinaCandidate:Q ZhaoFull Text:PDF
GTID:2121330338476422Subject:Materials Physics and Chemistry
Abstract/Summary:PDF Full Text Request
Low-dimensional Bi2Te3 crystals have been synthesized though a solvothermal route, and the influence of synthesis conditions on the crystal morphologies was investigated. The results show that the surfactant plays a key role in the formation of the final morphologies, the reaction temperature and experiment procedure have also important influence on it. Needle-shaped nanowires and nanotubes can be obtained using SDBS as surfactant, and flower-like clusters and nanosheets can be synthesized with PVP surfactant. The crystal can grow according to the"burst nucleation and diffusional growth"pattern using a two-step route so that the product with uniform morphologies can be obtained. Meanwhile, the crystal growth leading to different morphologies is controlled by crystal thermodynamics and dynamics, which could be adjusted by temperature. Then the thermoelectric properties of the product were studied, the power factor of the one-dimensional nanostructured Bi2Te3 increases with temperature and the highest value is 143.1μW·m-1K-2. Although the two-dimensional nanostructured Bi2Te3 has a high Seebeck coefficient of about 100μV/K at room temperature, due to the low electric conductivity, it's power factor maintain at about 23μW·m-1K-2 in a wide range of temperatures. Over all, the power factor of one-dimensional structured Bi2Te3 is higher than that of the two-dimensional one, especially at higher temperature.The conductivity of doped polyaniline and the synthesized Bi2Te3/polyaniline composites have also been studied. Polyaniline synthesized through doping, secondary doping and sulfosalicylic acid doping showed no significant differences. Bi2Te3 is so easily to be oxidized and acidized that it is impossible to synthesize the Bi2Te3/polyaniline composites directly through a chemical approach. The composites are finally prepared by mechanical blending, and the thermoelectric properties of the composites as well as the Bi2Te3 and polyaniline have been analyzed. The results reveal that the power factor of the polyaniline rises and falls as temperature increased, and the highest value appears at 326.5K, indicating it is appropriate to use at room temperature. The power factor of the mechanical blending composites is lower than those of both Bi2Te3 and polyaniline, and remains the same with the temperature rising, indicating that the mechanical blended composites couldn't improve the thermoelectric properties.
Keywords/Search Tags:Thermoelectric materials, low-dimensional structure, solvothermal, surfactant, chemical oxidation, polyaniline
PDF Full Text Request
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