成果報告書詳細
管理番号20160000000321
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 未利用廃熱回収を可能とする温度差を必要としない革新的発電材料の研究開発
公開日2016/5/17
報告書年度2015 - 2015
委託先名国立大学法人九州大学 ボッシュ株式会社 高周波熱錬株式会社
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. Research and development into innovative material for thermoelectric power generation without a temperature gradient for effective energy harvesting from unharnessed exhaust heat.

The purpose of this study plan is establishment of condition of synthesis of the composition gradient single clathrate Ba8AuxSi46-x crystal with a wide band gap n-type / a narrow band gap intrinsic / a wide band gap p-type semiconductor. We tried to estimate liquidus and solidus lines on Ba-Au-Si element system by differential scanning calorimetry. From this result, the composition gradient single clathrate Ba8AuxSi46-x crystal with a wide band gap n-type / a narrow band gap intrinsic / a wide band gap p-type semiconductor successfully can be synthesized by using Czochralski method with Ba8Au8Si38 melt.
We also tried to Ba8AuxSi46-x crystal thin film with p/n junction. This thin film was fabricated by sputtering Au on n-type single crystalline Ba8AuxSi46-x clathrate and the annealing. The composition gradient single clathrate Ba8AuxSi46-x crystal thin film with p/n junction can be synthesized.
Electric power generation without temperature difference was also performed. The sample was cut W5 x L10 x t1.5 mm along the pulling direction of CZ method. Electric power increased with the temperature. The generated electric voltage reached around 0.7 at 500 °C. No electric voltage can observe by the sample with no Au composition gradient. It is suggested that the Au composition gradient is needed for this novel power generation.
Large size single clathrate Ba8AuxSi46-x crystal was also synthesized for the mass production by Bridgmann method. 5 cm diameter x 5 cm length sample was successfully synthesized. As the results of the composition analysis, this sample has Au composition gradient.
Mechanical properties of clathrate crystal at high temperature were also measured. Thermal expansion coefficient of clathrate has 1.0 x 10^-5 /K and this value is closed to iron or nickel or titanium. These metals are suitable the electrodes for junction of clathrate element.
Low resistivity junction of clathrate and electrode was also investigated.
Low resistivity junction can be obtained by using Sn or Zn flux.
Test module with size of 4 x 4 cm including ten elements was fabricated.
Around 10 mV can be obtained at 400 °C. It suggested that the large voltage can be obtained by connecting the elements in series.
For this novel power generation, the sample with most narrow band gap than
n- or p-type semiconductor is needed. Ba8AuxSi46-x clathrate is suitable for this condition in previous study. However, other element system was not founded. We tried to investigate other clathrate by using ab initio calculations. These results suggested that Ba8CuxSi46-x clathrate is suitable for this novel power generation.
The organization of management committee was held three times. This committee was organized 10 companies, around 30 members.
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