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Revision as of 15:09, 21 September 2011 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - added verified revid - updated 'DrugBank_Ref', 'UNII_Ref', 'ChEMBL_Ref', 'ChEBI_Ref', 'KEGG_Ref', 'ChEBI_Ref') per Chem/Drugbox validation (report [[Wikipedia_talk:WikiProject_Chemicals|error← Previous edit		Latest revision as of 16:40, 26 September 2024 edit undoA Shortfall Of Gravitas (talk | contribs)Extended confirmed users721 edits Update the Inorganic chemistry text with a link to the copy on archive.org which is still a very useful reference, and make the cite more complete
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	{{Chembox		{{Chembox
			| Watchedfields = changed
	| verifiedrevid = 450836730
			| verifiedrevid = 451686130
	| ImageFile = Magnesium silicide.jpg
			| ImageFile1 = Antifluorite_Structure.jpg
	| ImageName = Sample of magnesium silicide as powder
			| ImageFile2 = Magnesium silicide.jpg
			| ImageName = Sample of magnesium silicide as powder
	| PIN = Magnesium silicide		| PIN = Magnesium silicide
	| Section1 = {{Chembox Identifiers		|Section1={{Chembox Identifiers
	| CASNo = 22831-39-6		| CASNo = 22831-39-6
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| PubChem = 89858		| PubChem = 89858
			| ChemSpiderID = 81111
	| PubChem_Ref = {{Pubchemcite|correct|PubChem}}
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 81111
			| EINECS = 245-254-5
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| EINECS = 245-254-5		| UNNumber = 2624
			| UNII_Ref = {{fdacite|correct|FDA}}
	| SMILES = ==
			| UNII = 475E6FMG3K
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
			| SMILES = ==
			| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI = 1S/2Mg.Si		| StdInChI = 1S/2Mg.Si
	| InChI = 1/2Mg.Si/rMg2Si/c1-3-2		| InChI = 1/2Mg.Si/rMg2Si/c1-3-2
	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChIKey = YTHCQFKNFVSQBC-UHFFFAOYSA-N		| StdInChIKey = YTHCQFKNFVSQBC-UHFFFAOYSA-N
	| InChIKey = YTHCQFKNFVSQBC-GEBTXNJDAA}}		| InChIKey = YTHCQFKNFVSQBC-GEBTXNJDAA
			}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
	| Mg = 2		| Mg=2 | Si=1
			| Appearance = Gray cubic crystals<ref name=b92/>
	| Si = 1
	| ExactMass = 75.947010329 g mol<sup>-1</sup>		| Density = 1.99 g cm<sup>−3</sup><ref name=b92>{{RubberBible92nd|page=4.74}}</ref>
			| MeltingPtC = 1102
	| Density = 1.988 g cm<sup>-3</sup>
			| MeltingPt_ref =<ref name=b92/>
	| MeltingPtC = 1102}}
			| Solubility = reacts<ref name=b92/>}}
	| Section7 = {{Chembox Hazards
			|Section3={{Chembox Structure
	| ExternalMSDS =
			|Structure_ref= <ref name=str>{{cite journal|url=https://www.jim.or.jp/journal/e/33/09/845.html|journal=Mater. Trans., JIM|year=1992|volume=33|issue=9|pages=845–850|author=Noda Y., Kon H., Furukawa Y., Otsuka N., Nishida I.A., Masumoto K.|title=Preparation and Thermoelectric Properties of Mg<sub>2</sub>Si<sub>1−x</sub>Ge<sub>x</sub> (x=0.0~0.4) Solid Solution Semiconductors|doi=10.2320/matertrans1989.33.845|doi-access=free}}</ref>
	| EUIndex = Not listed
			| CrystalStruct = ] (cubic), ]
	| EUClass =
			| SpaceGroup = Fm{{overline|3}}m, #225
	| RPhrases = {{R23}}, {{R24}}, {{R25}}, {{R34}}
	| SPhrases =		| Coordination =
			| LattConst_a = 0.6351 nm
	| MainHazards = reacts with water to give ]
	| NFPA-H =		| LattConst_b =
	| NFPA-F =		| LattConst_c =
	| NFPA-R =		| LattConst_alpha =
	| NFPA-O =		| LattConst_beta =
	| FlashPt =		| LattConst_gamma =
	| Autoignition = }}		| MolShape =
			| OrbitalHybridisation =
	| Section8 = {{Chembox Related
	| OtherAnions =		| Dipole =
			| UnitCellFormulas = 4
	| OtherCations = ]
	| OtherFunctn =
	| Function =
	| OtherCpds = }}
	}}		}}
			|Section7={{Chembox Hazards
	'''Magnesium silicide''', Mg<sub>2</sub>Si, is an ] consisting of ] and ]. As a powder magnesium silicide is dark blue or slightly purple in color. ], SiO<sub>2</sub>, found in ] and ], when heated with ] forms magnesium oxide, and, if an excess of magnesium is used, magnesium silicide is formed. The first product in this reaction is ], which then reacts further with magnesium to produce Mg<sub>2</sub>Si.
			| ExternalSDS =
	The stoichiometry of these reactions are such that with a 2:1 Mg:SiO<sub>2</sub> molar ratio, MgO is formed:
			| GHSPictograms = {{GHS02}}
	:2 Mg + SiO<sub>2</sub> → 2 ] + Si
			| GHSSignalWord = Warning
	If an excess of Mg is present, Mg<sub>2</sub>Si is formed from the reaction of the remaining magnesium with the silicon via:
			| HPhrases = {{H-phrases|261}}
	:2 Mg + Si → Mg<sub>2</sub>Si
			| PPhrases = {{P-phrases|231+232|280|370+378|402+404|501}}
	Hence, the overall reaction for the formation of magnesium silicide from a 4:1 Mg:SiO<sub>2</sub> molar ratio may be represented as:
			| MainHazards = reacts with water to produce pyrophoric ]
	:4 Mg + SiO<sub>2</sub> → 2 MgO + Mg<sub>2</sub>Si
			| NFPA-H =
	Theses reactions proceed violently, producing a great amount of heat.
			| NFPA-F =
			| NFPA-R =
			| NFPA-S =
			| FlashPt =
			| AutoignitionPt = }}
			|Section8={{Chembox Related
			| OtherAnions =
			| OtherCations = ]
			| OtherFunction =
			| OtherFunction_label =
			| OtherCompounds = }}
			}}
			'''Magnesium silicide''', Mg<sub>2</sub>Si, is an ] consisting of ] and ]. As-grown Mg<sub>2</sub>Si usually forms black crystals; they are ]s with n-type conductivity and have potential applications in ]s.<ref name=stam/>
			==Crystal structure==
	Magnesium silicide can also be formed by the reaction between ] and ] with the evolution of ] gas at temperatures above 250°C:
			Mg<sub>2</sub>Si crystallizes in the antifluorite structure. In the ] lattice Si centers occupy the corners and face-centered positions of the unit cell and Mg centers occupy eight tetrahedral sites in the interior of the unit cell. The coordination numbers of Si and Mg are eight and four, respectively.<ref name=str/>
	:2 MgH<sub>2</sub> + Si → Mg<sub>2</sub>Si + 2 H<sub>2</sub>
	This reaction releases 5 wt.% hydrogen and has been considered for ]. However, its reversibility has yet to be demonstrated.
			==Synthesis==
	Magnesium silicide is used to create aluminium alloys of the 6xxx group, containing up to approximately 1.5% Mg<sub>2</sub>Si. An alloy of this group can be age-hardened to form Guinier-Preston zones and a very fine precipitate, both resulting in increased strength of the alloy.<ref>'''''ASM Handbook''''', 10th Ed., Vol. 1, '''''Properties and Selection: Non-ferrous Alloys and Special Purpose Materials''''', 1990, ASM International, Materials Park, Ohio.</ref>
			]
			It can be produced by heating ], SiO<sub>2</sub>, found in ], with excess ]. The process first forms silicon metal and ], and, if an excess of SiO<sub>2</sub> is used, then elemental silicon is formed:
			:2 Mg + SiO<sub>2</sub> → 2 MgO + Si
			If an excess of Mg is present, Mg<sub>2</sub>Si is formed from the reaction of the remaining magnesium with the silicon:
			:2 Mg + Si → Mg<sub>2</sub>Si
			These reactions proceed exothermically,<ref name="brauer">{{cite book |last1=Ehrlich |first1=P. |editor1-last=Brauer |editor1-first=Georg |translator-last1=Riley |translator-last2=Reed F. |title=Handbook of Preparative Inorganic Chemistry |date=1963 |publisher=Academic Press, Inc. |location=New York |isbn=978-0121266011 |page=921 |volume=1 |edition=2nd |url=https://archive.org/download/Preperative_Inorganic_Chemistry_Brauer/Preperative_Inorganic_Chemistry_Brauer.pdf |access-date=26 September 2024 |language=English |chapter=17}}</ref> even explosively.<ref name=Stock>{{cite journal |doi=10.1002/cber.19160490114|title=Siliciumwasserstoffe. I. Die aus Magnesiumsilicid und Säuren entstehenden Siliciumwasserstoffe|year=1916|last1=Stock|first1=Alfred|last2=Somieski|first2=Carl|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=49|pages=111–157|url=https://zenodo.org/record/1426597}}</ref>
			==Reactions==
	When magnesium silicide is placed into ], HCl(aq), the gas ], SiH<sub>4</sub>, is produced. This gas is the silicon analogue of ], CH<sub>4</sub>, but is more reactive. Silane is ], that is, due to the presence of ], it spontaneously combusts in air:
			]
	:Mg<sub>2</sub>Si(s) + 4 HCl(aq) → SiH<sub>4</sub>(g) + 2 MgCl<sub>2</sub>(s)
			Magnesium silicide can be viewed as consisting of Si<sup>4−</sup> ions. As such it is reactive toward acids. Thus, when magnesium silicide is treated with ], ] (SiH<sub>4</sub>) and ] are produced:
	:SiH<sub>4</sub> + 2 O<sub>2</sub> → SiO<sub>2</sub> + 2 H<sub>2</sub>O
			:Mg<sub>2</sub>Si + 4 HCl → SiH<sub>4</sub> + 2 MgCl<sub>2</sub>
	These reactions are typical of a ] ]. Mg<sub>2</sub>Si reacts similarly with ]. ] silicides are even more reactive. For example, ], Na<sub>2</sub>Si, reacts rapidly with water to yield ], Na<sub>2</sub>SiO<sub>3</sub>, and ] gas.
			] can be used as well. These ] reactions are typical of a ] (]) and ] (]) ]s. The early development of silicon hydrides relied on this reaction.<ref name=Stock/>
			==Uses==
	==Crystal Structure==
			Magnesium silicide is used to create aluminium alloys of the ], containing up to approximately 1.5% Mg<sub>2</sub>Si. An alloy of this group can be age-hardened to form ]s and a very fine precipitate, both resulting in increased strength of the alloy.<ref>"Properties and Selection: Non-ferrous Alloys and Special Purpose Materials" in ''ASM Handbook'', 10th ed., Vol. 1, 1990, ASM International, Materials Park, Ohio. {{isbn|0871703785}}.</ref>
			Magnesium silicide is a ]. Its as-grown crystal exhibit n-type conductivity, but it can be changed to p-type by doping with Ag, Ga, Sn and possibly Li (at high doping level). The major potential electronic application of Mg<sub>2</sub>Si is in ]s.<ref name=stam/><ref name="Borisenko2013"/>
	Mg<sub>2</sub>Si crystallizes in a ] lattice. It possesses the structure with Si<sup>4-</sup> ions occupying the corners and face-centered positions of the unit cell and Mg<sup>2+</sup> ions occupying eight tetrahedral sites in the interior of the unit cell. There are also four equivalent interstitial sites.<ref> A. Kato et al. ''J. Phys: Condens. Matter'' '''21''' (2009) 205801.</ref>. Hence, the structure contains isolated Si<sup>4-</sup> ions. This feature makes the Si<sup>4 -</sup> ion of Mg<sub>2</sub>Si a good Brønsted–Lowry base (proton acceptor).
	==References==		==References==
			{{Commons category|Magnesium silicide}}
	<references/>
			{{reflist|refs=
			<ref name="Borisenko2013">{{cite book|author=Borisenko, Victor E. |title=Semiconducting Silicides: Basics, Formation, Properties|url=https://books.google.com/books?id=F0zoCAAAQBAJ&pg=PA187|date=2013|publisher=Springer Science & Business Media|isbn=978-3-642-59649-0|pages=187, 287}}</ref>
			<ref name=stam>{{cite journal|journal= Sci. Technol. Adv. Mater.|author=Hirayama, Naomi| year=2019|volume=20|issue=1|pages=160–172|title=Substitutional and interstitial impurity p-type doping of thermoelectric Mg<sub>2</sub>Si: a theoretical study|doi=10.1080/14686996.2019.1580537|pmid=30891103|pmc=6419642|bibcode=2019STAdM..20..160H}}{{open access}}</ref>
			}}
	]
	]
	{{inorganic-compound-stub}}
	{{Magnesium compounds}}		{{Magnesium compounds}}
			{{Silicides}}
			]
	]
			]
	]
			]