成果報告書詳細
管理番号20160000000278
タイトル*平成27年度中間年報 エネルギー・環境新技術先導プログラム 革新的ナノスケール制御による高効率熱電変換システムの実現
公開日2016/5/20
報告書年度2015 - 2015
委託先名国立大学法人茨城大学 国立大学法人埼玉大学 国立研究開発法人産業技術総合研究所 有限会社飛田理化硝子製作所
プロジェクト番号P14004
部署名イノベーション推進部
和文要約
英文要約Title: Advanced Research Program for Energy and Environmental Technologies / Realization of high-efficient thermoelectric conversion systems by utilizing innovative nanoscale control (FY2015-FY2016) FY2015 Annual Report

The quartz template for thermoelectric nanowire element has been prepared using application of the optical fiber technique. The cylindrical quartz template with around 1 mm-diameter contains the nanoscale pore, which is for the thermoelectric material. Although the fabrication technique for less-than-100 nm pore has been established, direct observation in the air was difficult. To overcome the problem, a large magnification microscope was installed into the apparatus for fabricating the template and the micro to nano-scale moving drive using combination of stepping motor and piezoelectric device was utilized to focus the fiber.
It is expected that the Bi nanowire with less-than-200nm diameter could dramatically enhance efficiency due to quantum confinement. The 594 nm-, 345nm-, and 150 nm-diameter of Bi thermoelectric nanowire were fabricated using the quartz template with millimeter-length. All nanowire elements were confirmed to be single crystal by Laue patterns. The temperature dependences of thermoelectric properties in these Bi nanowire were measured; however, the giant Seebeck coefficient has not been observed because the diameter was still larger to involve the quantum effect. However, the results show the hole mobility was increased even if the nanowire geometry was introduced. Especially, the 150 nm-diameter thermoelectric nanowire shows the resistivity was much smaller than that of the mean free path model. It implies that the mobility would be enhanced with much smaller-diameter nanowire.
The electrodes at both ends of the quartz template with 110nm-diameter Bi nanowire were fabricated by combination of ion-plating deposition and FIB-SEM. Thermoelectric properties of the bismuth nanowire were also measured. The measured electrical resistivity and the Seebeck coefficient were 1.91 m and -64.8 V/K at 300 K. The temperature dependence of thermoelectric properties of the bismuth nanowire will be evaluated as a next step.
In order to obtain electrical contact at nanowire edges with low contact resistance, the long-throw sputtering system have been developed. As a result, low pressure sputtering deposition was achieved, which is expected to overcome dishing at nanowire edges. Moreover, nano-pore structure has been fabricated to model nanowire edges encased in quartz template by FIB. By arranging ion beam, nano-pore with less-than 100 nm diameters could be fabricated.
In an analogous way to nanowires, low dimensional structure in bulk materials in which carriers are confined could result in enhanced Seebeck effect. In this project, fabrication of thermoelectric semiconductor–insulator nanocomposite was attempted. It has been found that the combination of the high energy ball milling and the spark plasma sintering processes results in the cell structure where Al2O3 particles surrounded by the Si semiconductor phase but with a micrometer scale. Longer time or higher energy ball milling will pursue finer structures.
ダウンロード成果報告書データベース(ユーザ登録必須)から、ダウンロードしてください。

▲トップに戻る