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Fabrication of Seebeck coefficient measurement system and thermoelectric properties in Sn1-xAgxTe compounds

Title
Fabrication of Seebeck coefficient measurement system and thermoelectric properties in Sn1-xAgxTe compounds
Authors
Cho, Hyun Yong
DGIST Authors
Cho, Hyun Yong; Kwon, Yong Seung; Kim, Dong Hwan
Advisor(s)
Kwon, Yong Seung
Co-Advisor(s)
Kim, Dong Hwan
Issue Date
2015
Available Date
2017-01-02
Degree Date
2015. 2
Type
Thesis
Keywords
SnTemixed phaseelectrical conductivitySeebeck coefficientpower factor섞인 상태전기전도도제백상수파워팩터
Abstract
Pb-based materials, which are superior for thermoelectric performance, environmentally have toxicity. Thus the materials should be alternated by non-toxic materials. Tin telluride (SnTe) is isostructural with PbTe and PbSe which are rock salt structure. In addition, SnTe is similar to the electronic band structure (two valence band system) with PbTe and PbSe. Thus, SnTe, which is overcome by low Seebeck coefficient and by large thermal conductivity, can be expected by good thermoelectric material. Thus, Ag-included poly crystals Sn1-xAgxTe (x=0.1, 0.2, 0.3, and 0.4) were prepared by box furnace and by hot press to confirm thermoelectric performance of the samples. By accident, we noticed difference that XRD patterns of Sn1-xAgxTe are changed from two phases (SnTe, AgTe) to mixed phase (SnTe/AgTe) before hot pressing and after. In addition, electrical conductivity of samples is maintained until high temperature. The power factor of sample to include silver(x=0.1) has maximum value (1.1 mW/mK2) at 673K. However, SnTe has higher power factor than Ag-included SnTe. Nevertheless, we can carefully expect that sample to include mixed phase obtain high electrical conductivity. Exceptionally, we developed the measurement of the thermoelectric power in the temperature range from 2K to 300K. By using two heaters, two thermometer, chip resistors, et al, measurement equipment is fabricated exactly. In addition, high density data is obtained by two heaters that are operated by turn. The system is controlled by LabVIEW software. In order to demonstrate this system, reference data of Pt wire and Ca10Nax(Pt3As8)(Fe2As2)5 superconductor were calibrated by developed equipment. Therefore we demonstrated the equipment with superior performance through confirming calculated data. ⓒ 2015 DGIST
Table Of Contents
Chapter 1. Introduction 1-- 1.1 Thermoelectric effect 1-- 1.2 Figure of merit (ZT) & Efficiency 2-- 1.3 Carrier concentration 4-- 1.4 Sn1-xAgxTe 5-- Chapter 2. Theory 9-- 2.1 Seebeck effect 9-- 2.2 Effects of charge carrier’s interactions on Seebeck coefficients 11-- 2.3 Thermal conductivity 13-- Chapter 3. Seebeck coefficient measuring equipment 15-- 3.1 Experimental setup 16-- 3.2 Operating principles 17-- 3.3 Calculation of sample Seebeck coefficient 18-- Chapter 4. Thermoelectric property of Sn1-xAgxTe 20-- 4.1 Experimental Methods 20-- 4.1.1 Sample preparation 20-- 4.1.2 Seebeck coefficient, Electrical conductivity measurement 22-- 4.2 Results and Discussion 23-- 4.2.1 X-Ray Diffraction 23-- 4.2.2 Scanning electron microscopy and Energy Dispersive Spectroscopy 26-- 4.2.3 Seebeck coefficient 28-- 4.2.4 Electrical conductivity 29-- 4.2.5 Power factor 30-- Chapter 5. Conclusion 31-- References 33-- Summary (in Korean) 35
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000001916045
http://hdl.handle.net/20.500.11750/1398
DOI
10.22677/thesis.1916045
Degree
Master
Department
Emerging materials Science
University
DGIST
Files:
Collection:
Emerging Materials ScienceThesesMaster


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