Metal Silicides and Phosphides

Metal silicides are prepared by the direct reaction of the elements. Reduction of a mixture of SiO and the metal oxide by carbothermic reaction provides another route. Reaction of metal oxides with silicon or SiC also yields silicides. Certain silicides can be made electrochemically (e.g. CrjSij). Silicides of various elements have been reviewed by Nowotny [1], 

NbjSi is prepared by vapour phase transport. Niobium metal and SiOj do not react when heated in vacuum at high temperatures (1370 K). In the presence of traces of H, gaseous SiO is formed. Gaseous SiO migrates to niobium to form the silicide. 

Metal phosphides (M3P to MP3) are prepared by the direct union of elements. Certain phosphides have been prepared by electrolysis (e.g. FeP). Reaction of oxides or halides with PH3 also yields phosphides. 

Essentials of Inorganic Materials Synthesis, First Edition. C.N.R. Rao and Kanishka Biswas. 2015 John Wiley Sons, Inc. Published 2015 by John Wiley Sons, Inc. 

Ga203 +2PH3 - 2GaP+3HjO SZnCl + PH3 - Zn P + 2HC1 

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