Title page for etd-0610117-220014


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URN etd-0610117-220014
Author Jie-Ru Deng
Author's Email Address No Public.
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Department Materials and Optoelectronic Science
Year 2016
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Engineering high-zT In-doped GeTe: the phase equilibria and thermoelectric properties
Date of Defense 2017-06-28
Page Count 170
Keyword
  • twin
  • liquidus projection
  • isothermal section
  • GeTe
  • Ge-Te-In
  • thermoelectric materials
  • Bridgman growth
  • Abstract Thermoelectric (TE) materials, which can convert waste heat into precious electricity, has been viewed as an effective solution for the worldwide energy issue. The simple cubic GeTe is known as a promising mid-temperature TE material, mainly owing to its excellent power factor. Minor doping might be effective in reducing the thermal conductivity of GeTe and thus enhancing the figure-of-merit (zT). Phase diagram, which provides basic yet essential information, probes the phase stability and thermodynamic behavior of complicated materials systems. With an aid of phase diagram and microstructural evolution, the TE properties can be optimized systematically. This study aims to determine the ternary phase diagrams of Ge-Te-In system, and the efforts include: (1) determining the liquidus projection by water-quenched alloys, (2) constructing the 350˚C isothermal section by thermally-equilibrated alloys, and (3) measuring the thermoelectric property of In-doped GeTe alloys. In this work, alloy (In2Te3)0.025(GeTe)2.925 reaches the highest peak value of zT~1.12 at 623K, showing 150% enhancement compared with that of the undoped GeTe (zT~0.75). On the basis of TEM analysis, the nano-sized twinning structure was discovered throughout the (In2Te3)0.025(GeTe)2.925, which leading to the reduced thermal conductivity and enhanced electrical conductivity.
    Advisory Committee
  • Shih-kang Lin - chair
  • Pai-Chun Wei - co-chair
  • - co-chair
  • Hsin-Jay Wu - advisor
  • Files
  • etd-0610117-220014.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2017-07-11

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