Silicon


Elemental silicon was prepared for the first time by Berzelius, in 1823, who placed silicon tetrafluoride in the presence of warm potassium. However, it was thought that Gay-Lussac and Thenard had already tried to obtain the amorphous silicon by the same method, in 1809. The substance obtained by Berzelius was a purer product as a result of exhausting filtering. Berzelius prepared silicon from the reaction of potassium fluorsilicates with potassium.

In its crystalline form, silicon was first prepared by Deville, in 1854, through the electrolysis of impure sodium-aluminum chloride with about 10% of silicon. At the beginning of the 20th century (1907), Potter studied the interaction of silica with the carbon, which prepared the way to the process of obtaining silicon for commercial purposes during the whole century.

The elemental silicon is commercially prepared by the heating of silicon dioxide with coal in electrical furnaces. To obtain monocrystalline silicon one can use the method of Czochralski that consists of introducing a crystalline seed in melted silicon, slowly lowering the temperature so that it crystallizes.

The common glass used to produce windows or bottles is primarily silica (75%), being the remaining 25% a mixture of Na2O (15 %), CaO (8 %) and Al2O3 (2,7 %). Sometimes some "impurities" are introduced in the glass, such as boron compounds, to increase the resistance to heat giving the commonly known "Pyrex".