|
Binary compounds of silicon are binary chemical compounds containing just silicon and another chemical element.〔''Inorganic chemistry'', Egon Wiberg,Nils Wiberg,Arnold Frederick Holleman〕 Technically the term silicide is reserved for any compounds containing silicon bonded to a more electropositive element. Binary silicon compounds can be grouped into several classes. Saltlike silicides are formed with group 1 and group 2 elements. Covalent silicides occur in compounds with groups 10 to 17. Transition metals form metallic silicides with the some exceptions: silver, gold and the group 12 elements. The general composition is MnSi or MSin with n ranging from 1 to 6. Examples are M5Si, M3Si (Cu, V, Cr, Mo, Mn, Fe, Pt, U), M2Si (Zr, Hf, Ta, Ir, Ru, Rh, Co, Ni, Ce), M3Si2 (Hf, Th, U), MSi (Ti, Zr, Hf, Fe, Ce, Th, Pu) and MSi2 (Ti, V, Nb, Ta, Cr, Mo, W, Re) The Kopp–Neumann law applies as: Cp(M,Si,) = xCp(M) + yCp(Si) As a general rule nonstochiometry implies instability. These intermetallics are in general resistant to hydrolysis, brittle, and melt at a lower temperature than the corresponding carbides or borides. They are electrical conductors. However, some, such as CrSi2, Mg2Si, β-FeSi2 and MnSi1.7, are semiconductors. Since degenerate semiconductors exhibit some metallic properties, such as luster and electrical conductivity which decreases with temperature, some silicides classified as metals may be semiconductors. ==Group 1== Silicides of group 1 elements are saltlike silicides, except for silane (SiH4) whose bonds to hydrogen are covalent. Higher silane homologues are disilane and trisilane. Polysilicon hydride is a two-dimensional polymer network. For lithium silicide many cluster compounds are known for example Li13Si4, Li22Si5, Li7Si3 and Li12Si7.〔''The Li-Si (Lithium-Silicon)'' system H. Okamoto Journal of Phase Equilibria Volume 11, Number 3, 306-312, 〕 Li4.4Si is prepared from silicon and lithium metal in high-energy Ball mill process.〔''Solid state ionics for batteries'', Tsutomu Minami,Masahiro Tatsumisago〕 Potential uses: electrode in lithium batteries. Li12Si7 has a Zintl phase with planar Si56− rings. Li NMR spectroscopy suggests these rings are aromatic.〔Bacsa, J., Hanke, F., Hindley, S., Odedra, R., Darling, G. R., Jones, A. C. and Steiner, A. (2011), The Solid-State Structures of Dimethylzinc and Diethylzinc. Angewandte Chemie International Edition, 50: 11685–11687. 〕 Other group 1 elements also form clusters: ''sodium silicide'' can be represented by NaSi, NaSi2 and Na11Si36〔''The na-si (sodium-silicon) system'' J Songster and A.D Pelton Journal of Phase Equilibria Volume 13, Number 1, 67-69, 〕 and potassium silicide by K8Si46. Group 1 silicides are in general high melting, metallic grey, with moderate to poor electrical conductance and prepared by heating the elements. Superconducting properties have been reported for Ba8Si46.〔High-Pressure Synthesis of a New Silicon Clathrate Superconductor, Ba8Si46 Shoji Yamanaka, Eiji Enishi, Hiroshi Fukuoka, and Masahiro Yasukawa Inorg. Chem., 2000, 39 (1), pp 56–58 〕 Several silicon Zintl ions (Si44− Si94−, Si52−) are known with group 1 counter ions.〔Scharfe, S., Kraus, F., Stegmaier, S., Schier, A. and Fässler, T. F. (2011), Zintl Ions, Cage Compounds, and Intermetalloid Clusters of Group 14 and Group 15 Elements. Angewandte Chemie International Edition, 50: 3630–3670. 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Binary compounds of silicon」の詳細全文を読む スポンサード リンク
|