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Preparation and Thermoelectric Properties of TiO2/β-Zn4Sb3 Composite

Author: GuJie
Tutor: XuHong；ZuoWeiLing
School: East China University of Science and Technology
Course: Materials Science and Engineering
Keywords: Thermoelectric materials β-Zn4Sb3 Spark Plasma Sintering
CLC: TB34
Type: Master's thesis
Year: 2011
Downloads: 16
Quote: 0
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Abstract


Thermoelectric materials is a way to achieve the mutual coupling of thermal and electrical energy conversion functional materials , development of pollution-free refrigeration system has important applications in the field of cogeneration . The the β-Zn4Sb3 compound is an important prospect warmed dielectric material , but because of its own is a heavily doped semiconductor , so by the micro-structure due to doping and band change is difficult to effectively improve the thermoelectric properties. Adding a second phase compound to form a composite material can reduce the thermal conductivity of the material , thereby enhancing the value of ZT . In this paper, molten slow cooling method preparation of single-phase the β-Zn4Sb3 compound , a series of different TiO2 content TiO2/β-Zn4Sb3 composite powders were prepared by mechanical mixing and chemical hydrolysis method , obtained by means of spark plasma sintering (SPS) forming a good bulk materials . The main research content and results are as follows : an important impact 1.Zn the added amount of the phase composition of the synthesized product . Purity zinc powder and antimony powder as a raw material, in accordance with the stoichiometric ratio, Zn excess 1.2at % , to obtain a mixture of two-phase the β-Zn4Sb3 and ZnSb , Zn excess 2.5at% obtained by reacting a single - phase β-Zn4Sb3 continue to increase the content of Zn , and the product appears in a single mass Zn . Were used mechanical mixing and chemical hydrolysis composite powder prepared TiO2 doped β-Zn4Sb3 SPS sintering molding , density reached more than 95% and 90 % , respectively . With the increase in TiO2 content , the decline in the conductivity of the composite material , Seebeck coefficient , and thermal conductivity decreases . 3 as a heterogeneous structure , TiO2 is introduced reducing the mobility of the charge carriers , improve the Seebeck coefficient of the composite material , reducing the conductivity of the material ; material within the phonon and carrier flow with increasing TiO2 content the scattering effect is enhanced, thus significantly reducing the thermal conductivity of the composite material . Composite bulk material in the experimental range of TiO2 second phase content of 7% and 5% ( mechanical method) (chemical method) ZT value of 0.68 and 0.71 in the 360 ℃ higher than the single-phase β-Zn4Sb3 19% and 25 %.

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