Characterizations And Applications Of Chalcogen Based Thermoelectric Bulk Materials Prepared By Solid State Microwave Synthesis
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Date
2013-07
Authors
Kadhim Abbas, Arej
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
This thesis aims to improve the output power (Pmax) of the thermoelectric generation module (TEG) through a cost reduction process. The preparation of Bi2Se3xTe3(1−x), Bi2xSb2(1−x)Te3 and Bi0.4Sb1.6Se3xTe3(1−x) bulk thermoelectric materials (ingots) (the mole fraction (x) for each formula = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) via a faster, simpler, and more economically feasible method called the solid state microwave synthesis is presented. This thesis also focuses on the structural and electrical characterization of the three sets after being cold pressed into disk form. The structural characterizations of the resulting samples are measured using several techniques such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD). The electrical characterizations include electrical conductivity (σ), the Hall effect, and the Seebeck coefficient (S) at temperatures ranging from 300 K to 523 K, and the voltage‒current (V-I) characteristics of the TEG modules.
The influence of x on the surface morphology, elemental compositions, and lattice constants of the Bi2Se3xTe3(1−x), Bi2xSb2(1−x)Te3, and Bi0.4Sb1.6Se3xTe3(1−x) samples was studied. Furthermore, the alloying effects on σ, carrier concentration (p), carrier mobility ( ), S, and the power factor (S2σ) were thoroughly investigated. The Se‒substitution for Te adjusts p to obtain an optimum value of 1.25 × 1020 cm-3 for the Bi2Se3xTe3(1−x) samples (x=0.2). The maximum S2σ is 2.85 mW/mK2 at 403 K based on the increased value of S for the Bi2Se0.6Te2.4 sample (176.3 μV/K).
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Keywords
Chalcogen Based Thermoelectric Bulk Materials , Solid State Microwave Synthesis