Silicide, calcium lithium

Advancing in this direction, we studied the possibility of synthesising carbides, borides and silicides of titanium, zirconium, niobium and tantalum in Li-LiCl and Ca-CaCl2 ionic-electronic melts. These melts are referred to as the ionic-electronic ones, because dissolved lithium and calcium dissociate to cations and delocalized electrons ... 

Crystalline silicon, which was ground to a powder having the grain size less than 160 pm and used for the s)mthesis, had a density of 2330 kg/m. Therefore, in the molten salts it subsided to the tube bottom, where silicon could contact the refractory metal powder. However, the direct contact area of the particles is very small as the particles are separated by a layer of the salt melt. Liquid lithium and calcium, which are soluble in their own chloride melts, can diffuse from the surface to the bulk of the salt melt and form silicides. 

By analogy with lower lithium and calcium borides, lower lithium (LuSi, Lii4Si6) and calcium (Ca2Si) silicides may, in our opinion, partially dissociate in ionic-electronic melts and form silicon anions of the hypothetical composition Si". These anions may serve as the silicon carriers from the silicon powder or higher silicides to the metal. This is followed by the formation of refractory silicides of rf-transition metals of the 4th and 5th groups. The hypothetical scheme of the silicon transfer through the salt melt is similar to the scheme given above for boron. 

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