1999 Fiscal Year Final Research Report Summary
FGM Forming of Thermoelectric materials by the Transport Method
| Project/Area Number |
10650680
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | Kogakuin University |
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Principal Investigator |
SHIOTA Ichiro Faculty of Engineering, Kogakuin University Professor, 工学部, 教授 (90255612)
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| Co-Investigator(Kenkyū-buntansha) |
KAIBE Hiromasa t. Tokyo Metropolitan University, Research Associate, 工学部・電気工学科, 助手 (40224331)
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| Project Period (FY) |
1998 – 1999
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| Keywords | PbTe / Bi_2Te_3 / Thermoelectric Material / FGM / Transport / Gas Transport Technique |
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| Research Abstract |
Fundamental research to fabricate a thermoelectric material with functionally graded structure was attempted by gas transport technique. The principle of the gas transport technique is as follows ; an element is evaporated at a high temperature site, and the gas phase element diffuses to a low temperature site. Then the element deposits to forms a crystal. The crystal by this technique is highly pure.
Pb and Te of 6-N(99.9999 %) were weighed to be a composition of stoichiometry, and 2-N Pbl_2 of 0.50 mass% was added (hereafter G) as an n-type dopant. A sample with Pbl_2 of 0.10mass% was also prepared (hereafter S). Each sample was encapsulated in a quartz tube in a vacuum. The mixture in the quartz tube was melted, agitated and solidified to form a starting material.
A single crystal growth with uniform carrier concentration was attempted as a pre-experiment. The starting material was pulverized and encapsulated in a quartz tube. The powder was stacked at one end of the quartz tube. The
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starting materials side was maintained at 1145 K and the other side was heated at 1083 K for 200 hours.
A crystal with graded carrier concentration was also attempted by two-step method. The starting materials were pulverized. The G was set at the crystal growth side and S was set at the starting materials side in a vacuum quartz tube. The G side was maintained at 1145 K, and S side was heated at 1083 K for 200 hours.
As the result, a single crystal was obtained by pre-experiment. It was clarified that a part of starting material once deposits at the part of 1113 - 1083 K, and it was transported to the other end of the quartz tube to form a single crystal in the crystal growth process.
It was confirmed that the S was grown continuously to the G in the case of two-step method. The result shows the feasibility of constructing an FGM of a thermoelectric material.
Electrode forming is also an important factor for constructing a thermoelectric module. Bi-Ag ally was found to be a promising solder in this experiment. Less
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