Electrodeposition of Silicon from Fluorosilicic Acid Produced in Iraqi Phosphate Fertilizer Plant

Abstract

The availability, low toxicity, and high degree of technological development make silicon the most likely material to be used in solar cells, the cost of solar cells depends entirely on cost of high purity silicon production. The present work was conducted to electrodeposite of silicon from K 2 SiF 6 , an inexpensive raw material prepared from fluorosilicic acid (H 2 SiF 6) produced in Iraqi Fertilizer plants, and using inexpensive graphite material as cathode electrode. The preparation of potassium fluorosilicate was performed at (60 o C) in a three necks flask provided with a stirrer ,while the electro deposition was performed at 750 o C in a three-electrodes configuration with melt containing in graphite pot. High purity potassium fluorosilicate (99.25%) was obtained at temperature (60 o C), molar ratio-KCl/H 2 SiF 6 (1.4) and agitation (600 rpm). Spongy compact deposits were obtained for silicon with purity not less than (99.97%) at cathode potential (−0.8 V vs. Pt), K 2 SiF 6 concentration (14% mole percent) with grain size (130 µm) and level of impurities (Cu, Fe and Ni) less than (0.02%).

Structural correlations and chemistry of the Na3AlF6 − SiO2 melt as an electrolyte for the solar grade silicon (SOG − Si) electrowinning

“…Some studies on electrochemistry of some fluoride and chloride systems have been published in the seventies and eighties of the 20 th century [4−6]. Also, in recent years, one can see an increasing interest in this field [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”