2005 Fiscal Year Final Research Report Summary
Development of new process for thermoelectric materials and devices of metal oxides
| Project/Area Number |
15560599
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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 |
Structural/Functional materials
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| Research Institution | Chiba University |
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Principal Investigator |
LU Yun Chiba University, Faculty of engineering, Assistant professor, 工学部, 講師 (50251179)
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| Co-Investigator(Kenkyū-buntansha) |
HIROHASHI Mitsuji Chiba University, Faculty of engineering, Professor, 工学部, 教授 (40009535)
SATO Kenkichi Chiba University, Faculty of engineering, Associate professor, 工学部, 助教授 (60143260)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Oxide / Thermoelectric material / Reduction Reaction / Powder metallurgy / Spark plasma sintering / Thermoelectric device |
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| Research Abstract |
In 2005 fiscal year, we have performed experiments about material fabrications, decrease of electrical resistivity, evaluation of thermoelectric properties and the test production of thermoelectric device on CuAlO_2 and TiO_<2-x> as oxide thermoelectric materials. To decrease electrical resistivity of CuAlO_2, we have tried grinding CuAlO_2, and adding copper powders into CuAlO_2. Also, we have carried out the reduction treatment using carbon powders to reduce non-stoichiometric titanium dioxide TiO_<2-x> fabricated by Spark Plasma Sintering (SPS), and then examined the non-stoichiometric number and carrier density by TG. The results of the research at 2005 fiscal year were concluded as follows :
1)CuAlO_2 compacts with high density were fabricated through using the ground powders. Thermoelectric properties were improved by the increase of Seebeck coefficient and the decrease of electrical resistivity based on increasing the density.
2)The compacts adding copper powders without oxidation were fabricated by the present process. The average diameter of the copper powders had a great influence on Seebeck coefficient, but the addition amount made electrical resistivity decreasing. There was the most decrease in electrical resistivity in the case of adding 1wt% of copper powders with average diameter of 1μm.
3)A large power factor,4.4×10^<-5>W・m<-1>・K^<-2> in the compact was obtained by grinding CuAlO_2 powders for 1.5 h, and was higher performance 5 times than the comparison sample. Also, electrical resistivity had the most low value in the case of adding 1wt% of copper powders with average diameter of 1μm.
4)By the reduction treatment to increase the carrier density and to decrease the electrical resistivity, the thermoelectric properties of TiO_<2-x> were considerably improved and a large power factor reaching 1×10^<-4> Wn^<-1>K^<-2> was obtained.
We had 2 paper publications,4 papers in press for publication and 6 research presentations from the above results.
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