2001 Fiscal Year Final Research Report Summary
Improvement in Systematized Photo-thermoelectric Energy Conversion Film by Controlling Mesoscopic Film Structure
| Project/Area Number |
12650658
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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 |
Physical properties of metals
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| Research Institution | Nagaoka University of Technology |
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Principal Investigator |
ISHIGURO Takashi Nagaoka University of Technology, Dept. of Electrical Engine., Associate Prof., 工学部, 助教授 (10183162)
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| Co-Investigator(Kenkyū-buntansha) |
HAMASAKI Katsuyoshi Nagaoka University of Technology, Dept. of Electrical Engine., Professor, 工学部, 教授 (40143820)
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| Project Period (FY) |
2000 – 2001
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| Keywords | solar absorber coating / functional graded structure / thermoelectric materials / mesoscopic structure / Seebeck coefficient / energy conversion film / ultra thin film / infrared ray |
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| Research Abstract |
In order to improve the performance of systematized photo-thermoelectric energy conversion film, individual functional components, i.e., photo-thermal conversion film and thermoelectric conversion film, are studied in the sense of controlling their mesoscopic structure.
As a photo-thermal energy conversion film, nano-structured Ag layers sandwiched between MgO layers are formed. The morphology of Ag layer changes systematically from the dispersed nano-particles to the continuous film via the intermediate nano-structures, i.e., the insular film or the maze-cracked film. It is found that the Ag films with these intermediate nano-structures have the effective optical properties applying to the solar absorber coating, i.e., the large absorptance at both visible and near infrared regions and the thermal stability. Based on the results obtained about the nano-structured Ag layers, a thermally stable selective solar absorber coating with the functional graded structure is successfully fabricat
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ed. Then the photo-thermal energy conversion efficiency of 0.72 for air mass one (AM1), 0.66 for AM1.5, and 0.59 for AM2 are realized at a typical operating temperature of 373K. Al-N films are also formed by rf sputtering using Ar and N_2 gas mixture. The concentration of partial N_2 gas pressure (C_<N2>) is changed. The specimen with 7.3%N_2 of C_<N2> shows the highest solar energy absorptance (α) of 0.95 for the air mass one. The reason for the high value of α is the antireflection effect due to the gradient-refractive index caused by the enhanced surface roughness during film growth.
In a promising thermoelectric material of CoSb_3, the problem is to reduce the thermal conductivity due to lattice. A possibility to form the porous morphology by using Co-Sb-N ternary system is examined. High density of vacancy with a scale of nanometer due to sublimation of N and/or Sb is successively formed. As a result, it may be mentioned that the formation of Co-Sb-N ternary film and following annealing is one of the noble methods to control the porous morphology of the film.
In order to evaluate thermal diffusivity of the film, the AC calorimetric method by using infrared camera instead of thermocouple is examined. This method is applied to the measurement of thermal diffusivuty of SUS304. Then the usefulness of the noncontact temperature measurement method is confirmed. Less
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Research Products
(2 results)
