Properties of silicon prepared from plant raw materials

High-purity X-ray amorphous silicon dioxide samples have been prepared by hydrolyzing siliconcontaining plants in a 0.1 N HCl solution, followed by calcination at 700°C in air. Reducing the silica with metallic magnesium, we obtained silicon, which was then purified by sequential washings with hydrochloric, hydrofluoric, and sulfuric acids and water. The fine silicon powder thus prepared, up to 97.6% in purity, ranging in color from light brown to dark brown, was characterized by X-ray diffraction and IR spectroscopy. According to total external reflection X-ray fluorescence, electron probe microanalysis, and chemical analysis data, the major impurities in the powder were silicon dioxide, iron (within 0.45%), titanium (within 0.10%), calcium (within 0.088%), and manganese (within 0.031%). According to scanning electron microscopy data, the silicon obtained has the form of spongy material ranging in pore size from 50 to 200 nm.