Multi-scale chemical characterization of a ground metallurgical-grade silicon powder

Laser-induced breakdown spectroscopy (LIBS) has been employed for the fast and reliable chemical characterization of silicon used for the photovoltaic industry. Silicon for photovoltaic panels is subject to certain constraints on its purity, and notably must contain low concentration of boron. The use of LIBS could be advantageous because it allows rapid and simultaneous multi-elemental chemical analysis of silicon without any sample preparation. LIBS was applied to boron analysis and a detection limit of 0.23 ppmw was found for optimized gas and pressure conditions.

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Electrolysis Process for Preparation of Solar Grade Silicon

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.391-392.697 ◽

2011 ◽

Vol 391-392 ◽

pp. 697-702 ◽

Cited By ~ 2

Author(s):

Xiang Yu Zou ◽

Hong Wei Xie ◽

Yu Chun Zhai ◽

Xiao Chuan Lang ◽

Jun Zhang

Keyword(s):

Electrochemical Method ◽

Silicon Powder ◽

Argon Atmosphere ◽

Impurity Level ◽

Solar Grade Silicon ◽

Metallurgical Grade Silicon ◽

Pure Silicon ◽

Cell Components ◽

Nickel Crucible ◽

Grade Silicon

Studied on electrorefining metallurgical grade silicon to prepare solar grade silicon(SOG-Si) with electrochemical method in molten KCl and NaF mixture salt. Molten KCl and NaF mixture salt as electrolyte, the metallurgical grade silicon as anode and little metal nickel crucible for collecting silicon powder as cathode, electrorefining experiments were performed at 800 and 2.0V for 14h under dry argon atmosphere. The results showed that the metallurgical grade silicon could be dissolved and deposited on the cathode through molten potassium chloride (KCl) and sodium fluoride (NaF) mixture salt electrolyte. The nickel crucible was full of deposit, which was pure silicon by XRD and EDS. Purity of refined silicon was close to 99.99%, most of impurities like B and P were reduced significantly. Impurity level of silicon was reduced to the desired range for SOG-Si by advancement of the materials for the cell components.

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Characterization of metallurgical grade silicon

Journal of Materials Research ◽

10.1557/jmr.1990.1894 ◽

1990 ◽

Vol 5 (9) ◽

pp. 1894-1899 ◽

Cited By ~ 42

Author(s):

J. C. Anglézio ◽

C. Servant ◽

F. Dubrous

Keyword(s):

Electron Microscopy ◽

Microprobe Analysis ◽

Electron Microprobe Analysis ◽

Optical Metallography ◽

Metallurgical Grade Silicon ◽

Transmission Electron ◽

Grade Silicon ◽

Precipitated Phases ◽

Scanning Electron

Optical metallography, scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy were used to characterize metallurgical grade silicon, produced in an electric are furnace. Coincidence fraction determinations were assumed to be Σ7 and Σ9 when grain boundaries are underlined by precipitated phases and Σ3 when they are not. The study of intergranular compounds was emphasized; ten compounds were found, the main ones being Si2Ca, Si8Al6Fe4Ca, Si2Al2Ca, Si2FeTi, and Si2.4Fe (α leboitc). The precipitation of these compounds was discussed according to the principal impurity concentrations in silicon. The crystalline structure of Si8Al6Fe4Ca was determined to be triclinic with a = 1.3923 nm, b = 1.3896 nm, c = 1.3900 nm and α = 92.4°, β = 110.3°, γ = 119.9°.

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Transition-Metal Impurities Removal from Metallurgical Grade Silicon by Electron Beam Injection

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.105 ◽

2011 ◽

Vol 675-677 ◽

pp. 105-108

Author(s):

Rui Xun Zou ◽

Da Chuan Jiang ◽

Wei Dong ◽

Zheng Gu ◽

Yi Tan

Keyword(s):

Electron Beam ◽

Transition Metal ◽

Removal Rate ◽

Silicon Powder ◽

Sio2 Film ◽

Metallurgical Grade Silicon ◽

Beam Injection ◽

Metal Impurities ◽

Transition Metal Impurities ◽

Grade Silicon

The electron beam injection (EBI) process involves offering electrons around silicon powder, whose surface was oxidized, and subsequently the powder is washed by HF acid so as to remove the SiO2 film. The new electron beam injection process, in which micro electric filed formed between Si and SiO2 film will accelerate impurities diffusion from Si to SiO2 film, was developed and applied to eliminate the transition-metal impurities of MG-Si. It is proved to be effective to remove transition-metal impurities from metallurgical grade silicon (MG-Si). By applying the electron beam injection method, the removal rate of 10% to 59% was achieved during the refining process. The efficiency of impurity removal originates from two aspects: the impurity concentration gradient on both sides of Si/SiO2 interface; the micro electric field formed from Si to SiO2 film. A further increase in the removal rate can be realized by controlling the processing parameters.

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Purification of metallurgical-grade silicon powder via chemical attack by hydrofluoric and nitric acids followed by thermal treatment

Materials Science in Semiconductor Processing ◽

10.1016/j.mssp.2013.06.006 ◽

2013 ◽

Vol 16 (6) ◽

pp. 1742-1746 ◽

Cited By ~ 11

Author(s):

Marouan Khalifa ◽

Malek Atyaoui ◽

Messaoud Hajji ◽

Rachid Ouertani ◽

Hatem Ezzaouia

Keyword(s):

Thermal Treatment ◽

Silicon Powder ◽

Metallurgical Grade Silicon ◽

Chemical Attack ◽

Grade Silicon

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Metal Impurities Removal from Metallurgical Grade Silicon by Hydrochloric Acid Leaching

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.813.7 ◽

2013 ◽

Vol 813 ◽

pp. 7-10 ◽

Cited By ~ 1

Author(s):

Xiao Ming Li ◽

Yan Mei Dang ◽

Wen Feng Li ◽

Jun Xue Zhao ◽

Ya Ru Cui

Keyword(s):

Particle Size ◽

Reaction Time ◽

Mass Fraction ◽

Acid Leaching ◽

Silicon Powder ◽

Metallurgical Grade Silicon ◽

Mechanical Stirring ◽

Grade Silicon ◽

Impurities Removal ◽

Hydrometallurgical Method

As a pre-treatment process for producing solar-grade silicon, hydrometallurgical method could remove the most of metallic impurities of metallurgical-grade silicon, which is a hopeful technology to provide solar energy material independence of the Siemens skill. Factors such as the hydrochloric mass fraction, temperature, reaction time, and particle size of silicon powders were investigated in the impurities removal experiments under the condition of mechanical stirring. The leached samples were analyzed by ICP and SEM. The optimum parameters, hydrochloric mass fraction 5%, temperature 80°C, reaction time 9h, particle size 75μm, were determined by single factor experiments and orthogonal experiments. The 86.1% of Fe, 68.1% of Al, 85.9% of Ca and 25.9% of B impurity was removed from metallurgical-grade silicon powder.

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