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Revision as of 13:24, 15 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 472453701 of page Bismuth_telluride for the Chem/Drugbox validation project (updated: '').		Latest revision as of 19:53, 21 August 2024 edit Polyamorph (talk | contribs)Extended confirmed users, Page movers, Pending changes reviewers, Rollbackers29,875 editsm →External links: clean upTag: AWB
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	{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
	{{chembox		{{chembox
			| Verifiedfields = changed
	| Watchedfields = changed		| Watchedfields = changed
	| verifiedrevid = 447901883		| verifiedrevid = 477000552
			| ImageFile1 = Монокристалл теллурида висмута.jpg
	| ImageFile = Bi2Te3structure.jpg
	| ImageSize =		| ImageSize1 =
			| ImageCaption1 = Single crystal of bismuth telluride
	| IUPACName =
			| ImageFile2 = Bi2Te3 structure 2.png
	| OtherNames =
			| ImageSize2 = 280px
	| Section1 = {{Chembox Identifiers
			| ImageCaption2 = Atomic structure: ideal (l) and with a ] (r)
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			| ImageFile3 = Twin in Bi2Te3 3.jpg
			| ImageSize3 =
			| ImageCaption3 = Electron micrograph of twinned bismuth telluride
			| IUPACName =
			| OtherNames =
			|Section1={{Chembox Identifiers
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 11278988		| ChemSpiderID = 11278988
	| InChI = 1/2Bi.3Te/q2*+3;3*-2		| InChI = 1/2Bi.3Te/q2*+3;3*-2
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	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| CASNo = 1304-82-1		| CASNo = 1304-82-1
			| UNII_Ref = {{fdacite|correct|FDA}}
	| PubChem =
			| UNII = 1818R19OHO
	| SMILES = ....
			| PubChem = 6379155
			| EINECS = 215-135-2
			| SMILES = ....
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
			| Bi=2|Te=3
	| Formula = Bi<sub>2</sub>Te<sub>3</sub>
			| Appearance = Grey powder or metallic grey crystals
	| MolarMass = 800.761 g/mol
			| Density = 7.74 g/cm<sup>3</sup><ref name=b92/>
	| Appearance = grey powder
			| MeltingPtC = 580
	| Density = 7.7 g/cm<sup>3</sup>
			| MeltingPt_ref = <ref name=b92>{{RubberBible92nd|page=4.52}}</ref>
	| MeltingPt = 585 C<ref name=prb1>{{cite journal| title =Electrical and Thermal Properties of Bi2Te3| journal=Phys. Rev.| volume= 108| year =1957| page=1164| doi=10.1103/PhysRev.108.1164| author =Satterthwaite, C. B.| last2 =Ure| first2 =R.| issue =5 }}</ref>
	| BoilingPt =		| BoilingPt =
	| Solubility =		| Solubility = insoluble<ref name=b92/>
			| SolubleOther = soluble<ref name=b92/>
			| Solvent = ]
	}}		}}
	| Section3 = {{Chembox Structure		|Section3={{Chembox Structure
	| CrystalStruct = ], ], SpaceGroup = R-3m, No. 166		| CrystalStruct = ], ]
			| SpaceGroup = R{{overline|3}}m, No. 166<ref name=str>{{cite journal|doi=10.1016/0025-5408(93)90055-I|title=A study of the phases in the bismuth – tellurium system|journal=Materials Research Bulletin|volume=28|issue=6|pages=591|year=1993|last1=Feutelais|first1=Y.|last2=Legendre|first2=B.|last3=Rodier|first3=N.|last4=Agafonov|first4=V.}}</ref>
			| LattConst_a = 0.4395 nm
			| LattConst_c = 3.044 nm
			| UnitCellFormulas = 3
	}}		}}
	| Section7 = {{Chembox Hazards		|Section7={{Chembox Hazards
			| ExternalSDS =
	| MainHazards =
	| FlashPt =		| MainHazards =
			| FlashPt = noncombustible
	| Autoignition =
			| FlashPt_ref=<ref name=PGCH/>
			| AutoignitionPt =
			| NFPA-H = 2 | NFPA-F = 0 | NFPA-R = 0
			| PEL = TWA 15 mg/m<sup>3</sup> (total) TWA 5 mg/m<sup>3</sup> (resp) (pure) <br /> none (doped with ]) <ref name=PGCH>{{PGCH|0056}}</ref>
			| REL = TWA 10 mg/m<sup>3</sup> (total) TWA 5 mg/m<sup>3</sup> (resp) (pure) TWA 5 mg/m<sup>3</sup> (doped with selenium sulfide)<ref name=PGCH/>
			| IDLH = N.D. (pure and doped)<ref name=PGCH/>
	}}		}}
			| Section9 = {{Chembox Related
			| OtherAnions = {{ubl|]|]|]}}
			| OtherCations = ]<br>]
			| OtherFunction =
			| OtherFunction_label =
			| OtherCompounds =
			}}
	}}		}}
			'''Bismuth telluride''' ({{chem2|Bi2Te3}}) is a gray powder that is a compound of ] and ] also known as bismuth(III) telluride. It is a ], which, when alloyed with ] or ], is an efficient ] material for refrigeration or portable power generation. {{chem2|Bi2Te3}} is a ], and thus exhibits thickness-dependent physical properties.
			==Properties as a thermoelectric material==
			Bismuth telluride is a ] layered semiconductor with a trigonal unit cell. The valence and conduction band structure can be described as a many-ellipsoidal model with 6 constant-energy ellipsoids that are centered on the reflection planes.<ref>{{cite journal| title =Anisotropy of the constant energy surfaces in p-type Bi<sub>2</sub>Te<sub>3</sub> and Bi<sub>2</sub>Se<sub>3</sub> from galvanomagnetic coefficients| journal=Phys. Rev. B| volume = 2 | year =1970| page=3209| doi=10.1103/PhysRevB.2.3209| author =Caywood, L. P.| last2 =Miller| first2 =G.| issue =8| bibcode=1970PhRvB...2.3209C}}</ref> {{chem2|Bi2Te3}} cleaves easily along the trigonal axis due to ] between neighboring tellurium atoms. Due to this, bismuth-telluride-based materials used for power generation or cooling applications must be polycrystalline. Furthermore, the ] of bulk {{chem2|Bi2Te3}} becomes compensated around room temperature, forcing the materials used in power-generation devices to be an alloy of bismuth, antimony, tellurium, and selenium.<ref name=prb1/>
			Recently, researchers have attempted to improve the efficiency of {{chem2|Bi2Te3}}-based materials by creating structures where one or more dimensions are reduced, such as nanowires or thin films. In one such instance ] bismuth telluride was shown to have an improved ] (voltage per unit temperature difference) of −287 μV/K at 54&nbsp;°C,<ref name="Tan"/> However, one must realize that Seebeck coefficient and electrical conductivity have a tradeoff: a higher Seebeck coefficient results in decreased carrier concentration and decreased electrical conductivity.<ref>{{cite journal|author1=Goldsmid, H. J. |author2=Sheard, A. R. |author3=Wright, D. A. |name-list-style=amp | title=The performance of bismuth telluride thermojunctions | journal=Br. J. Appl. Phys.|volume= 9|page= 365| year=1958|doi=10.1088/0508-3443/9/9/306|issue=9|bibcode=1958BJAP....9..365G }}</ref>
			In another case, researchers report that bismuth telluride has high ] of 1.1×10<sup>5</sup> S·m/m<sup>2</sup> with its very low lattice ] of 1.20 W/(m·K), similar to ordinary ].<ref>{{cite news| author=Takeiishi, M. |display-authors=et al| url=http://www.jstp2006.kues.kyoto-u.ac.jp/CD-final-Data/papers/J113.pdf | title=Thermal conductivity measurements of Bismuth Telluride thin films by using the 3 Omega method| accessdate=2009-06-06| publisher=The 27th Japan Symposium on Thermophysical Properties, 2006, Kyoto |archiveurl = https://web.archive.org/web/20070628110900/http://www.jstp2006.kues.kyoto-u.ac.jp/CD-final-Data/papers/J113.pdf |archivedate = 2007-06-28}}</ref>
			==Properties as a topological insulator==
			Bismuth telluride is a well-studied topological insulator. Its physical properties have been shown to change at highly reduced thicknesses, when its conducting surface states are exposed and isolated. These thin samples are obtained through either ] or mechanical exfoliation.
			Epitaxial growth methods such as molecular beam epitaxy and metal organic chemical vapor deposition are common methods of obtaining thin {{chem2|Bi2Te3}} samples. The stoichiometry of samples obtained through such techniques can vary greatly between experiments, so ] is often used to determine relative purity. However, thin {{chem2|Bi2Te3}} samples are resistant to Raman spectroscopy due to their low melting point and poor heat dispersion.<ref>{{cite journal|last1=Teweldebrhan|first1=D.|last2=Goyal|first2=V.|last3=Balandin|first3=A. A|title=From Graphene to Bismuth Telluride: Mechanical Exfoliation of Quasi-2D Crystals for Applications in Thermoelectrics and Topological Insulators|journal=Nano Letters|date=2010|volume=10|issue=12|pages=1209–18|doi=10.1021/nl903590b |pmid=20205455|bibcode=2010NanoL..10.1209T}}</ref>
			The crystalline structure of {{chem2|Bi2Te3}} allows for mechanical exfoliation of thin samples by cleaving along the trigonal axis. This process is significantly lower in yield than epitaxial growth, but produces samples without defects or impurities. Similar to extracting ] from bulk graphite samples, this is done by applying and removing ] from successively thinner samples. This procedure has been used to obtain {{chem2|Bi2Te3}} flakes with a thickness of 1&nbsp;nm.<ref>{{cite journal|doi=10.1149/1.3485611|title="Graphene-Like" Exfoliation of Atomically-Thin Films of Bi|pages=103–117|journal=ECS Transactions|year=2010|last1=Teweldebrhan|first1=Desalegne|last2=Balandin|first2=Alexander A.|s2cid=139017503 }}</ref> However, this process can leave significant amounts of adhesive residue on a standard Si/SiO<sub>2</sub> ], which in turn obscure ] measurements and inhibit the placement of contacts on the substrate for purposes of testing. Common cleaning techniques such as oxygen plasma, boiling ] and ] are ineffective in removing residue.<ref>{{Cite journal | doi=10.1080/14786435.2012.728009| title=AFM and Raman studies of topological insulator materials subject to argon plasma etching| journal=]| volume=93| issue=6| pages=681–689| year=2013| last1=Childres| first1=Isaac| last2=Tian| first2=Jifa| last3=Miotkowski| first3=Ireneusz| last4=Chen| first4=Yong| bibcode=2013PMag...93..681C| arxiv=1209.2919| s2cid=38149843}}</ref>
			==Occurrence and preparation==
			The ] form of {{chem2|Bi2Te3}} is ] which is moderately rare.<ref>{{Cite web |title=Tellurobismuthite |url=https://www.mindat.org/show.php?id=3907 |access-date=November 28, 2023 |website=Mindat.org}}</ref><ref>{{Cite journal |last=Kingsbury |first=A.W.G. |date=1965 |title=Tellurbismuth and meneghinite, two minerals new to Britain |url=https://www.cambridge.org/core/product/identifier/S0369014800001247/type/journal_article |journal=Mineralogical Magazine and Journal of the Mineralogical Society |language=en |volume=35 |issue=270 |pages=424–426 |doi=10.1180/minmag.1965.035.270.19 |bibcode=1965MinM...35..424K |issn=0369-0148}}</ref> There are many natural bismuth tellurides of different ], as well as compounds of the Bi-Te-S-(Se) system, like {{chem2|Bi2Te2S}} (]). These bismuth tellurides are part of the tetradymite group of minerals.<ref>{{Cite web |title=Tetradymite Group |url=https://www.mindat.org/min-29337.html |access-date=November 28, 2023 |website=Mindat.org}}</ref>
			Bismuth telluride may be prepared simply by sealing mixed powders of bismuth and tellurium metal in a quartz tube under vacuum (critical, as an unsealed or leaking sample may explode in a furnace) and heating it to 800&nbsp;°C in a ].
			==See also==
			*]
			*]
			*]
			==References==
			{{reflist|refs=
			<ref name=prb1>{{cite journal| title =Electrical and Thermal Properties of Bi<sub>2</sub>Te<sub>3</sub>| journal=Phys. Rev.| volume= 108| year =1957| page=1164| doi=10.1103/PhysRev.108.1164| author =Satterthwaite, C. B.| last2 =Ure| first2 =R.| issue =5 | bibcode=1957PhRv..108.1164S}}</ref>
			<ref name="Tan">{{cite book| doi=10.1117/12.609819| year=2005| author=Tan, J.| editor-first1=Carles| editor-first2=Jung-Chih| editor-first3=Fernando| editor-last1=Cane| editor-last2=Chiao| editor-last3=Vidal Verdu| title=Smart Sensors, Actuators, and MEMS II| volume=5836| pages=711–718| chapter=Thermoelectric properties of bismuth telluride thin films deposited by radio frequency magnetron sputtering| journal=Smart Sensors| bibcode=2005SPIE.5836..711T| s2cid=123199126}}</ref>
			}}
			==External links==
			*{{Commons category-inline|Bismuth telluride}}
			*
			*
			{{Bismuth compounds}}
			{{Tellurides}}
			]
			]
			]
			]