| Project/Area Number |
10450279
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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 | 一般 |
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| Research Field |
Metal making engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
YAMAUCHI Chikabumi Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (40115647)
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| Co-Investigator(Kenkyū-buntansha) |
FUJISAWA Toshiharu Graduate School of Engineering, Professor, 難処理人工物研究センター, 教授 (20115629)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥15,900,000 (Direct Cost: ¥15,900,000)
Fiscal Year 1999: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1998: ¥11,300,000 (Direct Cost: ¥11,300,000)
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| Keywords | Silicon for Solar Cells / Production Process / Chemical Equilibration Technique / Thermodynamic Data / Vacuum melting / Slag / Distribution Ratio / Gas Injection / 太陽電池 / シリコン / 不純物除去 / 活量 / 活量係数 / 相互作用係数 / 標準生成自由エネルギー |
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| Research Abstract |
In order to develop a new high efficient production process of silicon for solar cells by refining inexpensive metallurgical grade silicon, following experiments were conducted.
1. The thermodynamic data (the activity coefficients, the interaction parameters and so on) related to impurities such as boron, aluminum, calcium, oxygen and nitrogen in molten silicon at 1723K and 1773K were measured by using the chemical equilibration techniques.
2. Vacuum refining under the atmosphere of 10 Pa was applied for removing phosphorus, calcium and aluminum from molten silicon by using vacuum treatment was also examined from the thermodynamic viewpoint.
3. Slag treatments were applied for removing boron and phosphorus from molten silicon.
(1) The distribution ratios of boron and phosphorus between slags and molten silicon which are defined as :
Lx ≡(mass% of X in slag)/[mass% of X in molten silicon], X = B or P
were measured under an inert gas atmosphere at 1723 K and 1773 K and the following results were obtained :
・ High value of distribution ratio of boron is not achieved even by using the NaOィイD20.5ィエD2-CaO-SiOィイD22ィエD2 slag saturated with SiOィイD22ィエD2, because high basically and high oxygen potential can not be simultaneously achieved in this process.
・ High value of distribution ratio of phosphorus between the CaO-CaFィイD22ィエD2 slag saturated with CaO and molten silicon is achieved under the condition of lower oxygen potential.
(2) The CaO-CaFィイD22ィエD2 slag addition-oxidizing gas injection method was applied for removing boron from molten silicon at 1773 K. Nearly 85 % of boron could be rapidly removed from molten silicon.
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