Silicide

silicide [′sil·ə‚sīd]

(chemistry)

A binary compound in which silicon is bonded with a more electropositive element.

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Silicide 

any of the chemical compounds of silicon with metals and certain nonmetals. Suicides can be divided into three basic groups according to the type of chemical bond: ionic-co-valent, covalent, and metallic. Ionic-covalent suicides are formed from alkali metals (with the exception of sodium and potassium), alkaline-earth metals, and metals of the copper and zinc subgroups. Covalent suicides are formed from boron, carbon, nitrogen, oxygen, phosphorus, and sulfur and can be referred to as, for example, borides, carbides, and nitrides of silicon. Metallic silicides are formed from transition metals.

Suicides are obtained by fusing or sintering a powdery mixture of Si and a given metal or by heating metal oxides with Si, SiC, SiO₂, and natural or synthetic silicates (sometimes mixed with carbon). Other methods include the interaction of a metal with a mixture of SiCl₄ and H₂ and the electrolysis of melts composed of K₂SiF₆ and an oxide of a given metal.

Covalent and metallic suicides, in addition to being refractory, are resistant to oxidation and the action of mineral acids and various aggressive gases. Suicides are used in heat-resistant cermet composition materials in aviation and rocket engineering. MoSi₂ is used in the manufacture of heaters for furnaces heated by electrical resistance and operating under exposure to air at temperatures up to 1600°C. FeSi₂, Fe₃Si₂, and Fe₂Si are constituents of ferrosilicon, which is used in the deoxidation and alloying of steel. Silicon carbide is a semiconductor material.

REFERENCES

Nekrasov, B. V. Osnovy obshchei khimii, 3rd ed., vols. 1-2. Moscow, 1973.
Gel’d, P. V., and F. A. Sidorenko. Silitsidy perekhodnykh metallov chetvertogo perioda. Moscow, 1971. [23–1081–]