1997 Fiscal Year Final Research Report Summary
Metal to insulator transition of VO2-based thin films prepared by a coating method and its application to smart windows
| Project/Area Number |
08555213
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
工業物理化学
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| Research Institution | University of Tokyo |
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Principal Investigator |
KUDO Tetsuichi Univ.of Tokyo, Inst.of Industrial Science, Professor, 生産技術研究所, 教授 (90205097)
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| Co-Investigator(Kenkyū-buntansha) |
INOUE Toshiki Toyota Automatic Loom Works, Ltd., 生産開発研究所, 主任研究員
HIBINO Mitsuhiro Univ.of Tokyo, Inst.of Industrial Science, Assistant, 生産技術研究所, 助手 (20270910)
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| Project Period (FY) |
1996 – 1997
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| Keywords | vanadium dioxide / semiconductor-metal transition / smart window / wet coating |
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| Research Abstract |
It is known that vanadium dioxide VO2 undergoes a semiconductor-metal transition at 67C and its transmittance of infrared ray changes concomitantly. Thus smart windows utilizing this switching phenomenon of the compound absorb much attention from an energy saving point of view. However, the transition temperature Tc=67C is too high for practical use. Moreover, conventional preparing methods of VO2 film including the sputtering technique are mot practical for producing large area window. The purpose of this study is to obtain VO2-based films with Tc near room temperature by an inexpensive coating method. We have succeeded in developing a new method using polyvanadic acid as a starting material (coating solution), which is synthesized by the reaction of metallic vanadium with hydrogen peroxide. A thin film of VO2 is easily prepared by heating such a coated film in a reducing H2 atmosphere at moderate temperature. This method is advantageous also for doping metal elements to control Tc. For example, we succeeded in obtaining tungsten doped VO2 films, V1-xWx02, using poly-tungsto-vanadic acid precursor synthesized similarly by reacting a mixture of metallic vanadium and tungsten with hydrogen peroxide. A film at x=0.015 showed a sharp transition at about 30C.We confirmed Tc is lowered by 18C per molar % of W.A systematic study of the doping effect was also carried out using double doped films with tungsten and molybdenum. As a result, the Vegard type rule was confirmed to hold for the effect of each element to reduce Tc.
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Research Products
(2 results)
