Removal of iron and titanium in poly-crystalline silicon by acid leaching

Tomohiro Sakata; Takahiro Miki; Kazuki Morita

doi:10.2320/jinstmet1952.66.5_459

Removal of iron and titanium in poly-crystalline silicon by acid leaching

Tomohiro Sakata, Takahiro Miki, Kazuki Morita

ENG - Metallurgy

Research output: Contribution to journal › Article › peer-review

27 Citations (Scopus)

Abstract

Removal of Fe and Ti from Si by acid leaching method was examined, the optimum condition for acid leaching was obtained and the mechanism of removal of impurities in Si was estimated. Si-Ca-(Fe, Ti) alloys with various compositions were subjected to acid leaching procedure using aqua regia. For most of the samples, 85∼96% of Fe and 80∼93% of Ti were removed from Si and the effects of cooling rate and alloy composition were studied. Slow cooling (4.4 K/min) was found to be better for effective removal of impurities than quenching. In order to give a higher removal rate of iron, acid soluble CaSi₂ phase should be precipitated as a secondary phase, namely X_Ca/X_Fe > 6.5. On the other hand, the optimum composition for the removal of Ti is considered to be X_Ca/X_Ti = 3.

Original language	English
Pages (from-to)	459-465
Number of pages	7
Journal	Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume	66
Issue number	5
DOIs	https://doi.org/10.2320/jinstmet1952.66.5_459
Publication status	Published - 2002 May

Keywords

Acid leaching
Aqua regia
Calcium
Grain boundary
Iron
Phase diagram
Phase equilibrium
Segregation coefficient
Silicon
Solidification
Titanium

ASJC Scopus subject areas

Condensed Matter Physics
Mechanics of Materials
Metals and Alloys
Materials Chemistry

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abstract = "Removal of Fe and Ti from Si by acid leaching method was examined, the optimum condition for acid leaching was obtained and the mechanism of removal of impurities in Si was estimated. Si-Ca-(Fe, Ti) alloys with various compositions were subjected to acid leaching procedure using aqua regia. For most of the samples, 85∼96% of Fe and 80∼93% of Ti were removed from Si and the effects of cooling rate and alloy composition were studied. Slow cooling (4.4 K/min) was found to be better for effective removal of impurities than quenching. In order to give a higher removal rate of iron, acid soluble CaSi2 phase should be precipitated as a secondary phase, namely XCa/XFe > 6.5. On the other hand, the optimum composition for the removal of Ti is considered to be XCa/XTi = 3.",

keywords = "Acid leaching, Aqua regia, Calcium, Grain boundary, Iron, Phase diagram, Phase equilibrium, Segregation coefficient, Silicon, Solidification, Titanium",

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T1 - Removal of iron and titanium in poly-crystalline silicon by acid leaching

AU - Sakata, Tomohiro

AU - Miki, Takahiro

AU - Morita, Kazuki

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Y1 - 2002/5

N2 - Removal of Fe and Ti from Si by acid leaching method was examined, the optimum condition for acid leaching was obtained and the mechanism of removal of impurities in Si was estimated. Si-Ca-(Fe, Ti) alloys with various compositions were subjected to acid leaching procedure using aqua regia. For most of the samples, 85∼96% of Fe and 80∼93% of Ti were removed from Si and the effects of cooling rate and alloy composition were studied. Slow cooling (4.4 K/min) was found to be better for effective removal of impurities than quenching. In order to give a higher removal rate of iron, acid soluble CaSi2 phase should be precipitated as a secondary phase, namely XCa/XFe > 6.5. On the other hand, the optimum composition for the removal of Ti is considered to be XCa/XTi = 3.

AB - Removal of Fe and Ti from Si by acid leaching method was examined, the optimum condition for acid leaching was obtained and the mechanism of removal of impurities in Si was estimated. Si-Ca-(Fe, Ti) alloys with various compositions were subjected to acid leaching procedure using aqua regia. For most of the samples, 85∼96% of Fe and 80∼93% of Ti were removed from Si and the effects of cooling rate and alloy composition were studied. Slow cooling (4.4 K/min) was found to be better for effective removal of impurities than quenching. In order to give a higher removal rate of iron, acid soluble CaSi2 phase should be precipitated as a secondary phase, namely XCa/XFe > 6.5. On the other hand, the optimum composition for the removal of Ti is considered to be XCa/XTi = 3.

KW - Acid leaching

KW - Aqua regia

KW - Calcium

KW - Grain boundary

KW - Iron

KW - Phase diagram

KW - Phase equilibrium

KW - Segregation coefficient

KW - Silicon

KW - Solidification

KW - Titanium

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