Hydrometallurgical Purification of Metallurgical Grade Silicon with

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Hydrometallurgical Purification of Metallurgical Grade Silicon with Hydrogen Peroxide in Hydrofluoric Acid Huixian Lai, Liuqing Huang, Huaping Xiong, Chuanhai Gan, Pengfei Xing, Jintang Li, and Xuetao Luo Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.6b02245 • Publication Date (Web): 16 Dec 2016 Downloaded from http://pubs.acs.org on December 20, 2016

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Industrial & Engineering Chemistry Research

1

Hydrometallurgical Purification of Metallurgical Grade Silicon with

2

Hydrogen Peroxide in Hydrofluoric Acid

3

Huixian Laia, Liuqing Huanga, Huaping Xionga, Chuanhai Gana, Pengfei Xingb,

4

Jintang Lia and Xuetao Luoa,∗

5

a

University, Xiamen 361005, P R China

6 7

b

School of Materials and Metallurgy, Northeastern University, Shenyang 110004, P R China

8 9

Fujian Key Laboratory of Advanced Materials, College of Materials, Xiamen

Abstract

10

The effect of adding hydrogen peroxide (H2O2) as an oxidizing agent on purifying

11

metallurgical grade silicon (MG-Si) by leaching with hydrofluoric acid (HF) was

12

studied as a function of leaching temperature, particle size, leaching duration and

13

concentration of leaching agents. It was found that the extraction capacity for metallic

14

impurities could be significantly enhanced with introducing H2O2 into HF lixiviant

15

showing litter dependence on HF concentration. By leaching with 1 mol· L-1 HF plus

16

2 mol· L-1 H2O2 for only 0.25 h at 55 ℃, the MG-Si purity could be upgraded from

17

99.74% to 99.96%, to 99.99% with further prolonging leaching duration. The

18

sensitivity sequences of precipitates to each etchant were obtained through revealing

19

the micro-structural evolution of MG-Si before and after etching. With the help of

20

Raman spectrometry and transmission electron microscopy, the chemical etching

21

mechanism was discussed.

22

∗

Corresponding author: Xuetao Luo (E-mail: [email protected], Tel: +86-592-2188503) 1

ACS Paragon Plus Environment


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Keywords: hydrometallurgical purification; hydrogen peroxide; metallurgical grade

2

silicon; extraction

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 2


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1. Introduction

2

Rising energy demands, limited reserves of fossil fuels, and the environmental

3

pollutions associated with them are the motivators of a drastic change in our fuel-base

4

energy towards alternative and renewable sources such as solar energy, wind energy

5

and biomass energy. Among them, solar energy features the most abundant renewable

6

energy. Even though many semiconductor compounds have been synthesized, solar

7

grade silicon (SOG-Si, 99.9999% in purity) is still a key material for converting solar

8

energy into electricity in the photovoltaic industry. Today, wafer-based crystalline

9

silicon solar modules account for a total market share of >90% at the global

10

photovoltaic market 1, 2. Therefore, for achieving the widespread use of solar cell, it is

11

meaningful to develop a cost-effective method to lower the cost of SOG-Si.

12

High price SOG-Si is usually produced by modified Siemens process or Fluidized

13

bed method, which purifies silicon material through converting metallurgical grade

14

silicon (MG-Si, 99% in purity) into gaseous compounds, followed by distillation,

15

reduction and deposition into high-purity silicon. Those methods are complicated,

16

energy-intensive and dangerous. Thus, the potential for cost reduction in these

17

processes is limited. A low-cost process for producing SOG-Si, metallurgical routes,

18

was developed recently using MG-Si as a starting material. Metallurgical methods

19

such as acid leaching

20

solidification

21

advantages of low cost and low level of energy consumption, among which acid

22

leaching is a method of low temperature, consuming less energy and using simple

11, 12

3-5

, plasma refining

, slag treatment

13, 14

6, 7

, vacuum refining

8-10

, directional

have been widely investigated due to the

3



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instruments. Therefore, acid leaching is one of the most commonly used methods and

2

always uses as a viable pretreatment method prior to the main metallurgical refining

3

processes. Duo to the promising advantages, acid leaching method has been widely

4

15

5

investigated for upgrading MG-Si to SOG-Si. Early in 1927, Tucker

first proposed

6

the method of acid leaching for preparing high purity silicon. After that, much effort

7

has been taken to look for effective acid leaching conditions. Hunt et al.

8

removing more than 90% of the impurities in MG-Si using an average particles size of

9

less than 50 µm by leaching with aqua regia at 75 ℃ for 12 h. Ma et al.

16

achieved

17

have

10

investigated different acids and found that the extraction yield of impurities was

11

increased by 9% with hydrofluoric acid leaching compared with hydrochloric acid

12

and nitric acid at 50 ℃ for 8 h. Up to 85% iron and 75% aluminum were removed

13

using 6 mol/L undisclosed acid C at 60 ℃ for 4 days

14

removal efficiency, sequential leaching or refluxing process was adopted. Santos et al.

15

4

16

particle size, time, temperature and concentration of leaching agents (HNO3, H2SO4,

17

HCl and HF), and reported that using only hydrochloric acid (16%, 5 h, 80 ℃) and a

18

relatively coarse fraction (116 µm), it is possible to removal ~80% of the impurities

19

and to obtain 99.9% pure silicon after further leaching with hydrofluoric acid (2.5%, 2

20

h, 80 ℃). Juneja and Mukherjee

21

refluxing silicon with aqua regia and hydrofluoric acid, and found that leaching with

22

hydrofluoric acid was more efficient than leaching with aqua regia. To improve

18

. For improving impurity

made a detailed study in purification of MG-Si by acid leaching at the conditions of

19

conducted acid leaching process involving

4


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20

1

reaction kinetics of acid leaching, Xie et al.

2

high pressure and reported that more than 90% extraction of iron could be achieved

3

by pressure leaching of MG-Si with hydrochloric acid. The kinetics of iron removal

4

from metallurgical grade silicon with pressure leaching have also been studied by Yu

5

et al. 21. In spite of numerous investigations on upgrading MG-Si by acid leaching, the

6

leaching efficiency was not satisfied in the case of achieving high impurity removal. A

7

more effective acid leaching solution should be found to purify MG-Si.

8 9

have conducted acid leaching under

It is reported that adding hydrogen peroxide into hydrofluoric is highly beneficial for metallic impurity removal

22

. Iron, Aluminum and Calcium were reduced by

10

98.8%, 98.0% and 81%, respectively. The present study seeks to build on this by

11

mainly focus on chemical etching mechanism. It is favorable to add more

12

fundamental information about acid leaching metallurgical grade silicon. Additionally,

13

some complexing agents (acetic acid and oxalic acid) were introduced in the lixiviant

14

for enhancing impurities removal.

15

2. Experiments

16

2.1. Materials and reagents

17

The MG-Si feedstock and analytical grade chemicals (hydrofluoric acid, hydrogen

18

peroxide, acetic acid and oxalic acid) were purchased from Run Xiang Co., Ltd.,

19

China and Sinopharm Chemical Reagent Co., Ltd., China, respectively. The

20

concentrations of main impurities in the as-received MG-Si with various size ranges

21

were listed in table 1. The average compositions of the different size ranges are close

22

to the compositions of the MG-Si with mixed particle size, suggesting that no 5



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significant contamination occurred during the crushing and grinding processes.

2

However, it is evident that the sieving process concentrated the impurities in the finer

3

fractions, presumably due to the fact that the impurity phases are very friable.

4

Distilled water and analytical grade chemicals were used to prepare all the leaching

5

solutions.

6

Table 1 Impurity concentration in MG-Si of various sizes Impurity concentration (ppmw) Impurity elements >154µm 74~154µm 38~74µm > Si-Al-Fe-Ni, Si-V-Ti-(Mn) > Si-Ti-Fe>Si-Fe >> Si-Al-Ni-(Cu)

6

As exhibited in Figure 7(b), the Si-Al-Fe phase is also first dissolved in HF plus

7

H2O2 solution after 5 min of etching, then Si-Al-Fe-Ni, Si-V-Ti-(Mn), Si-Ti-Fe, Si-Fe

8

and Si-Al-Ni-(Cu) after prolonging etching time. Therefore, the following sensitivity

9

sequence to the HF plus H2O2 can be deduced for these phases:

10

Si-Al-Fe>> Si-Al-Fe-Ni, Si-V-Ti-(Mn) > Si-Ti-Fe, Si-Fe, Si-Al-Ni-(Cu)

11

However, after prolonging etching time, the phenomenon of etching silicon matrix

12

will be found with some cracks and holes remaining on the smooth surface. On the

13

one hand, as metallic impurities favor to enrich at the grain boundaries due to its low

14

segregation coefficient in silicon

15

beneficial for the fragmentation of the silicon matrix exposing the impurities to the

16

action of etchants. However, etching silicon will increase silicon loss.

17

3.4 Chemical etching mechanism in etching process

4, 27

, etching silicon boundary producing cracking is

18

In order to understand the corrosion mechanism during acid leaching process, it is

19

important to detect how the chemical state of silicon surface changes in the process.

20

Surface Raman spectroscopy has some advantages in monitoring the surface bonding

21

and has been used in investigating the silicon surface bonds successfully in the

22

cleaning and texturing process for manufacturing solar cell or large-scale integration 16


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31-34

1

circuits

. Therefore, in this case, Raman spectroscopy was used to detect the

2

changes in silicon surface bonds before and after acid leaching, and the results were

3

present in Figure 8.

4

The bonds at 520 cm-1 and 960 cm-1 were assigned to the first and the second orders

5

of the bulk Si-Si vibration, respectively 35. However, the intensities of them decrease

6

after acid leaching with two kinds of lixiviants, and as compared to others, the

7

intensity of Si-Si vibration in the silicon after leaching with HF and H2O2 mixture is

8

lowest. This phenomenon may be attributed to the decrease in concentration of Si-Si

9

bond on silicon surface during acid leaching. Part of Si-Si bond is substituted by other

10

bonds such as Si-H, Si-F and Si-O. As we all known, silicon is hard to dissolve in HF

11

solution in oxidant-free solution, while after adding oxidizing agent, the dissolution

12

rate of silicon in HF solution is improved significantly

13

with the conclusion found in Section 3.3. Based on Raman measurement on the solid

14

state silicon wafer surface, the bonds at 300, 617 and 823 cm-1 are also assigned to the

15

silicon substrate

16

intensity of this bond decreases after acid leaching as a result of dissolution by HF

17

acid. Adding H2O2 in the etchant makes the surface atoms oxidized and the silicon

18

surface is terminated by oxygen atoms. The reaction equation can be described as

19

equation (1) 37, 39, 40:

20

Si + 2H 2 O + 4h + → SiO 2 + 4H +

21

where h+ represents a hole. And then the oxygen terminations are dissolved by HF

22

and substituted by F and H atoms as following equations showed 36, 37:

36, 37

. This result is consistent

33, 34

. The position of 430 cm-1 was signified as SiO2

31, 38

. The

(1)

17



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SiO 2 + 6HF → SiF62− + 2H 2 O + 2H +

(2)

2

SiO 2 + 3HF2− → SiF62− + H 2 O + OH −

(3)

3

It should be noted that the vibration frequency of Si-F bond increases with the

4

decrease of coordinated atom number of F, which ranges from 600-900 cm-1 34, 35.

5

Thus, we assign 663 cm-1 to the stretching vibration of Si-F bond in HxSiFy. The

6

downshift of Si-Si bonds located at 520 and 960 cm-1 is also found in Figure 8. This

7

phenomenon is easy to be understood based on quantum confinement effect, which is

8

much related with the surface roughness (porosity) 35, 41. As discussed above, HF plus

9

H2O2 mixture features better property in silicon erosion than HF alone. Thus, the level

10

of grain refinement is supposed to be obvious after HF and H2O2 etching as shown in

11

Figure 9.

12 13 14

Figure 8 Raman spectra of MG-Si before and after acid leaching. (Duration: 2h; temperature: 55 ℃; HF concentration: 2 mol· L-1; H2O2 concentration: 2 mol· L-1)

18


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1 2 3 4

Figure 9 (a) TEM image of MG-Si after leaching by 2.0 mol· L-1 HF and 2.0 mol· L-1 H2O2 mixture and its enlarged TEM image corresponding to the rectangular red area (b).

5

As shown in Figure 9, the micro-pores are established under the attack of HF plus

6

H2O2 etchant. It is crucial to demonstrate the mechanism responsible for the porosity

7

on the silicon surface. A possible scheme for forming porous silicon is illustrated as

8

Fig. 10 based on a model of quantum confinement effect proposed by Lehmann et al.

9

42, 43

. Electron transfer is necessary for oxidation and dissolution of silicon. As

10

illustrated in Figure 10(b), the electrochemical potential of H2O2 ( E H 2O 2 / H 2O : 1.763 V)

11

is much more positive than the valence band of silicon (EVB: 0.67 V). From the energy

12

point of view, H2O2 can inject holes into the valence band of silicon through reduction

13

reaction 37:

14

H 2 O 2 + 2H + → 2H 2 O + 2h +

15

where h+ represents a hole. It should be noted that the bandgap of a silicon crystallite

16

will increase as a result of quantum confinement effects if its sizes are reduced to a

17

few nanometers. The same is true for the thin silicon walls separating the micro-pores.

18

As compared to the bandgap energy of bulk silicon, the increase in bandgap energy in

(4)

19



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the wall region produces an energy barrier for holes ∆EV, as schematically shown in

2

Figure 10(b). If ∆EV is larger than the bias-dependent energy of holes, the porous

3

region becomes depleted of holes and therefore passivated against further dissolution.

4

Thus, it is more energetically beneficial for a hole to enter the electrolyte at the pore

5

tip directly (solid arrow), than via the porous structure (dotted arrow).

6

A silicon surface is known to be virtually invert against attack of hydrofluoric acid －

concentrations

42, 43

7

at low pH values, which corresponds to low OH

. A Si-O-Si

8

bridge will be established with consuming one hydroxy and two holes as depicted in

9

Figure 10a (step 1, 2). As Monk et al. reported 44, the dissolution of the oxide resultant

10

in HF involves nucleophilic attack of silicon by fluorine-containing species, such as

11

HF, HF2− , and electrophilic attack of the H+ ion on the oxygen back bonded to the

12

silicon as shown in Figure 10a (step 3 ,4). These reactions are thought to proceed

13

simultaneously on the silicon surface and compete with each other in rate.

14 15 16 17

Figure 10 (a) Schematic illustration of chemical etching of silicon; (b) the corresponding band diagram for charge transfer from the bulk to the porous skeleton or to the pore tip; (c) the enlarged view of the selected area of a) 42, 43.

18 20


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1

4. Conclusions

2

The hydrometallurgical purification of MG-Si by leaching with HF in the presence

3

of H2O2 as an oxidizing agent was investigated under different conditions of leaching

4

temperature, particle size, lixiviant composition and leaching duration. After

5

introducing H2O2 into HF lixiviant, the extraction capacity for metallic impurities can

6

be significantly enhanced, especially for Cu with extraction efficiency increasing from

7

23.98% to 92.88% when leaching MG-Si in 2 mol· L-1 HF plus 2 mol· L-1 H2O2.

8

Accordingly, when increasing leaching temperature higher than 55 ℃, the extraction

9

efficiency for Cu decreases dramatically. The leaching yields of impurities will

10

increase with decrease in particle size, but taking grinding cost into consideration,

11

particle size fraction of 74~154 µm will be suitable for SOG-Si production. What is

12

more, the phenomenon of cracking effect by the lixiviant will be more obvious with

13

increasing particle size of silicon, which is beneficial for impurity removal. It is found

14

that the silicon purity increases from 99.74% to more than 99.96% after only 0.25 h

15

leaching by 1 mol· L-1 HF plus 2 mol· L-1 H2O2 with particle size of 74~154 µm.

16

After prolonging leaching duration, 99.99% pure silicon can be achieved. And an

17

obvious increase in purity of silicon cannot be found with increasing HF

18

concentration. According to reveal the micro-structural evolution of MG-Si after

19

etching with different lixiviants, sensitivity sequences of precipitates to HF, alone and

20

associated with H2O2 can be obtained. In addition, the influences of two complexing

21

agents (oxalic acid and acetic acid) on the impurity extraction by HF plus H2O2 are

22

moderated. Different types of MG-Si from different origins may be responsible for 21



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1

that. After Raman analysis, it is reasonable that etching silicon starts with first

2

oxidizing reaction by H2O2 and then dissolve by HF. Like Si-Si bonds, some Si-F and

3

Si-O bonds can also be found on silicon surface after acid etching with HF plus H2O2

4

etchant.

5

Acknowledgements

6

We gratefully acknowledge the support of the National Natural Science Foundation

7

of China (No. 51334004) and the Scientific and Technological Innovation Platform of

8

Fujian Province (2006L2003). Moreover, the authors are grateful to Tintin Fang and

9

Yun Zhong for their support in proofreading the article.

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References

2

1.

3

materials: Present efficiencies and future challenges. Science 2016, 352, (6283),

4

307-317.

5

2.

Lynch, D., Winning the global race for solar silicon. JOM 2009, 61, (11), 41-48.

6

3.

Kim, J.; No, J.; Choi, S.; Lee, J.; Jang, B., Effects of a New Acid Mixture on

7

Extraction of the Main Impurities from Metallurgical Grade Silicon. Hydrometallurgy

8

2015, 157, 234-238.

9

4.

Polman, A.; Knight, M.; Garnett, E. C.; Ehrler, B.; Sinke, W. C., Photovoltaic

Santos, I. C.; Goncalves, A. P.; Santos, C. S.; Almeida, M.; Afonso, M. H.; Cruz,

10

M. J., Purification of metallurgical grade silicon by acid leaching. Hydrometallurgy

11

1990, 23, (2-3), 237-246.

12

5.

13

acid leaching of silicon for solar cells. Chem. Eng. Trans 2003, 3, 449-454.

14

6.

15

silicon by a steam-added plasma melting method. Mater. Trans., JIM 2004, 45, (3),

16

858-864.

17

7.

18

process to provide solar-grade silicon. Sol. Energy Mater. Sol. Cells 2002, 72, (1–4),

19

69-75.

20

8.

21

from silicon by induction vacuum refining. Sep. Purif. Technol. 2011, 82, (0),

22

128-137.

Aguiar, M.; Mei, P., Effect of temperature and particle size on the purification by

Nakamura, N.; Baba, H.; Sakaguchi, Y.; Kato, Y., Boron removal in molten

Delannoy, Y.; Alemany, C.; Li, K. I.; Proulx, P.; Trassy, C., Plasma-refining

Zheng, S. S.; Abel Engh, T.; Tangstad, M.; Luo, X. T., Separation of Phosphorus

23



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1

9.

Zheng, S. S.; Abel Engh, T.; Tangstad, M.; Luo, X. T., Numerical Simulation of

2

Phosphorus Removal from Silicon by Induction Vacuum Refining. Metall. Mater.

3

Trans. A 2011, 42, (8), 2214-2225.

4

10. Côrtes, A. D. S.; Silva, D. S.; Viana, G. A.; Motta, E. F.; Zampieri, P. R.; Mei, P.

5

R.; Marques, F. C., Solar cells from upgraded metallurgical-grade silicon purified by

6

metallurgical routes. J. Renew. Sustain. Ener. 2013, 5, (2), 023129, 1-9.

7

11. Gan, C. H.; Zeng, X.; Fang, M.; Zhang, L.; Qiu, S.; Li, J. T.; Jiang, D. C.; Tan, Y.;

8

Luo, X. T., Effect of calcium-oxide on the removal of calcium during industrial

9

directional solidification of upgraded metallurgical-grade silicon. J. Cryst. Growth

10

2015, 426, 202-207.

11

12. Li, T. F.; Huang, H. C.; Tsai, H. W.; Lan, A.; Chuck, C.; Lan, C. W., An enhanced

12

cooling design in directional solidification for high quality multi-crystalline solar

13

silicon. J. Cryst. Growth 2012, 340, (1), 202-208.

14

13. Lai, H. X.; Huang, L. Q.; Lu, C. H.; Fang, M.; Ma, W. H.; Xing, P. F.; Li, J. T.;

15

Luo, X. T., Reaction Mechanism and Kinetics of Boron Removal from

16

Metallurgical-Grade Silicon Based on Li2O-SiO2 Slags. JOM 2015, 1-10.

17

14. Fang, M.; Lu, C. H.; Huang, L. Q.; Lai, H. X.; Chen, J.; Yang, X. B.; Li, J. T.; Ma,

18

W. H.; Xing, P. F.; Luo, X. T., Multiple Slag Operation on Boron Removal from

19

Metallurgical-Grade Silicon Using Na2O-SiO2 Slags. Ind. Eng. Chem. Res. 2014, 53,

20

(30), 12054-12062.

21

15. Tucker, N. P., Alloys of iron research, Part VII, Preparation of high purity silicon.

22

Journal of Iron and Steel Industry 1927, 15, 412-414. 24


Page 24 of 29

Page 25 of 29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1

16. Hunt, L. P.; Dosaj, V. D.; McCormick, J. R.; Crossman, L. D., Purification of

2

metallurgical-grade silicon to solar-grade quality. Electrochem. Soc. 1976, 200-215.

3

17. Ma, X. D.; Zhang, J.; Wang, T. M.; Li, T. J., Hydrometallurgical purification of

4

metallurgical grade silicon. Rare Metals 2009, 28, (3), 221-225.

5

18. Yu, Z. L.; Ma, W. H.; Dai, Y. N.; Yang, B.; Liu, D. C.; Dai, W. P.; Wang, j. X.,

6

Removal of iron and aluminum impurities from metallurgical grade silicon with

7

hydrometallurgical route. Trans. Nonferrous Met. Soc. China 2007, 17, (sB1),

8

1030-1033.

9

19. Juneja, J. M.; Mukherjee, T. K., A study of the purification of metallurgical grade

10

silicon. Hydrometallurgy 1986, 16, (1), 69-75.

11

20. Xie, K. Q.; Yu, Z. L.; Ma, W. H.; Zhou, Y.; Dai, Y. N., Removal of iron from

12

metallurgical grade silicon with pressure leaching. Advanced Material Science and

13

Technology 2011, 675-677, 873-876.

14

21. Yu, Z. L.; Xie, K. Q.; Ma, W. H.; Zhou, Y.; Xie, G.; Dai, Y. N., Kinetics of iron

15

removal from metallurgical grade silicon with pressure leaching. Rare Metals 2011,

16

30, (6), 688-694.

17

22. Liu, Y. Q.; Xue, J. L.; Zhu, J., Hydrometallurgical Study of Purifying M-G

18

Silicon Feedstock for Solar Cells Production. TMS Annual Meeting 2012, 79-86.

19

23. Lai, H. X.; Huang, L. Q.; Lu, C. H.; Fang, M.; Ma, W. H.; Xing, P. F.; Li, J. T.;

20

Luo, X. T., Leaching behavior of impurities in Ca-alloyed metallurgical grade silicon.

21

Hydrometallurgy 2015, 156, (0), 173-181.

22

24. Antonijević, M. M.; Janković, Z. D.; Dimitrijević, M. D., Kinetics of chalcopyrite 25



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1

dissolution by hydrogen peroxide in sulphuric acid. Hydrometallurgy 2004, 71, (3–4),

2

329-334.

3

25. Olubambi, P. A.; Potgieter, J. H., Investigation on the metchanisms of sulfuric

4

acid leaching of chalcopyrite in the presence of hydrogen peroxide. Miner. Process.

5

Extr. Metall. Rev. 2009, 30, (4), 327-345.

6

26. Zhang, H.; Wang, Z.; Ma, W. H.; Xie, K. Q.; Hu, L., Chemical Cracking Effect of

7

Aqua Regia on the Purification of Metallurgical-Grade Silicon. Ind. Eng. Chem.

8

Res.2013, 52, (22), 7289-7296.

9

27. Fang, M.; Lu, C. H.; Huang, L. Q.; Lai, H. X.; Chen, J.; Li, J. T.; Ma, W. H.; Xing,

10

P. F.; Luo, X. T., Effect of Calcium-Based Slag Treatment on Hydrometallurgical

11

Purification of Metallurgical-Grade Silicon. Ind. Eng. Chem. Res. 2014, 53, (2),

12

972-979.

13

28. Guo, C. J.; Huang, Y. F.; Zhong, M. T.; Li, H.; Sun, Y. H.; Chen, H. Y.,

14

Determination of Trace Amounts of Boron in Polysilicon by Differential Pulse

15

Voltammetry After Hydrofluoric Acid/Nitric Acid Treatment. International Journal of

16

Electrochemical Science 2011, 6, (12), 6525 - 6541.

17

29. Şahin, Đ.; Nakiboğlu, N., Voltammetric determination of boron by using Alizarin

18

Red S. Anal. Chim. Acta 2006, 572, (2), 253-258.

19

30. Sun, Y. H.; Ye, Q. H.; Guo, C. J.; Chen, H. Y.; Lang, X.; David, F.; Luo, Q. W.;

20

Yang, C. M., Purification of metallurgical-grade silicon via acid leaching, calcination

21

and quenching before boron complexation. Hydrometallurgy 2013, 139, 64-72.

22

31. Moreno, M.; Daineka, D.; Roca i Cabarrocas, P., Plasma texturing for silicon 26


Page 26 of 29

Page 27 of 29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1

solar cells: From pyramids to inverted pyramids-like structures. Sol. Energy Mater.

2

Sol. Cells 2010, 94, (5), 733-737.

3

32. Chu, Q. M.; Liu, X.; Zhang, P. X.; Dai, Y. N., Formation mechanism of Si (1 0 0)

4

surface morphology in alkaline fluoride solutions. Appl. Surf. Sci. 2011, 257, (22),

5

9503-9506.

6

33. Wang, J.; Tu, H.; Zhou, Q.; Zhu, W.; Liu, A., In situ Raman spectroscopy study

7

on silicon surface in NH4OH/H2O2 and HCl/H2O2 aqueous solutions. Microelectron.

8

Eng. 2001, 56, (1–2), 221-225.

9

34. Wang, J.; Tu, H. L.; Zhu, W. X.; Zhou, Q. G.; Liu, A. S.; Zhang, C., A

10

comparative Raman spectroscopy study on silicon surface in HF, HF/H2O2 and

11

HF/NH4F aqueous solutions. Mater. Sci. Eng., B 2000, 72, (2–3), 193-196.

12

35. Ren, B.; Liu, F. M.; Xie, J.; Mao, B. W.; Zu, Y. B.; Tian, Z. Q., In situ monitoring

13

of Raman scattering and photoluminescence from silicon surfaces in HF aqueous

14

solutions. Appl. Phys. Lett. 1998, 72, (8), 933-935.

15

36. Kolasinski, K. W., Etching of silicon in fluoride solutions. Surf. Sci. 2009, 603,

16

(10–12), 1904-1911.

17

37. Huang, Z. P.; Geyer, N.; Werner, P.; de Boor, J.; Gosele, U., Metal-Assisted

18

Chemical Etching of Silicon: A Review. Adv. Mater. 2011, 23, (2), 285-308.

19

38. Galeener, F. L.; Lucovsky, G., Longitudinal Optical Vibrations in Glasses: GeO2

20

and SiO2. Phys. Rev. Lett. 1976, 37, (22), 1474-1478.

21

39. Chartier, C.; Bastide, S.; Lévy-Clément, C., Metal-assisted chemical etching of

22

silicon in HF–H2O2. Electrochim. Acta 2008, 53, (17), 5509-5516. 27



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1

40. Nahm, K. S.; Seo, Y. H.; Lee, H. J., Formation mechanism of stains during Si

2

etching reaction in HF–oxidizing agent–H2O solutions. J. Appl. Phys.1997, 81, (5),

3

2418-2424.

4

41. Ossadnik, C.; Vepřek, S.; Gregora, I., Applicability of Raman scattering for the

5

characterization of nanocrystalline silicon. Thin Solid Films 1999, 337, (1–2),

6

148-151.

7

42. Lehmann, V.; Gösele, U., Porous silicon formation: A quantum wire effect. Appl.

8

Phys. Lett. 1991, 58, (8), 856-858.

9

43. Lehmann, V., Electrochemistry of Silicon: Instrumentation, Science, Materials

10

and Applications. Electrochemistry of Silicon: Instrumentation, Science, Materials

11

and Applications, Wiley-VCH Verlag GmbH: 2002.

12

44. Monk, D. J.; Soane, D. S.; Howe, R. T., A review of the chemical reaction

13

mechanism and kinetics for hydrofluoric acid etching of silicon dioxide for surface

14

micromachining applications. Thin Solid Films 1993, 232, (1), 1-12.

15 16 17 18 19 20 21 22 28


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