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			{{Short description|Chemical compound}}
	{{chembox
			{{Chembox
⚫	| verifiedrevid = 396295678
			| Verifiedfields = changed
			| Watchedfields = changed
		⚫	| verifiedrevid = 413666960
	| Name = Barium fluoride		| Name = Barium fluoride
			| ImageFile1 =Barium fluoride crystal sample.jpg
	| ImageFile =Fluorite-unit-cell-3D-ionic.png		| ImageFile2 =Fluorite-unit-cell-3D-ionic.png
	| ImageName = Barium fluoride
	| Section1 = {{Chembox Identifiers		|Section1={{Chembox Identifiers
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}		| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 56421		| ChemSpiderID = 56421
			| SMILES = FF
	| InChI = 1/Ba.2FH/h;2*1H/q+2;;/p-2
	| SMILES = ..		| SMILES2 = ..
	| InChIKey = OYLGJCQECKOTOL-NUQVWONBAV
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI = 1S/Ba.2FH/h;2*1H/q+2;;/p-2		| StdInChI = 1S/Ba.2FH/h;2*1H/q+2;;/p-2
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	| CASNo = 7787-32-8		| CASNo = 7787-32-8
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
			| UNII_Ref = {{fdacite|correct|FDA}}
			| UNII = H96A02I53Y
	| RTECS = CQ9100000		| RTECS = CQ9100000
			| PubChem = 62670
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
	| Formula = BaF<sub>2</sub>		| Formula = {{chem2|BaF2}}
	| MolarMass = 175.34 g/mol		| MolarMass = 175.324 g/mol<ref name=crc>Haynes, p. 4.49</ref>
	| Appearance = white cubic crystals		| Appearance = white cubic crystals<ref name=crc/>
	| Density = 4.893 g/cm<sup>3</sup>		| Density = 4.893 g/cm<sup>3</sup><ref name=crc/>
	| Solubility = 0.16 g/100 mL (20 °C)		| Solubility = 1.58 g/L (10 °C)<br />1.61 g/L (25 °C)<ref>Haynes, p. 5.167</ref>
	| SolubleOther = soluble in ], ]		| SolubleOther = soluble in ], ]
			| SolubilityProduct = 1.84·10<sup>−7</sup><ref name="crc99">{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=4–47|edition=99th |language=English}}</ref>
	| MeltingPt = 1368 °C
	| BoilingPt = 2260 °C		| MeltingPtC = 1368
			| MeltingPt_ref = <ref name=crc/>
			| BoilingPtC = 2260
			| BoilingPt_ref = <ref name=crc/>
			| RefractIndex = {{ubl|1.557 (200 nm)|1.4744 (589 nm)|1.4014 (10 μm)}}<ref>Haynes, p. 10.248</ref>
			| ThermalConductivity = 10.9 W/(m·K)<ref>Haynes, p. 12.222</ref>
			| MagSus = −51·10<sup>−6</sup> cm<sup>3</sup>/mol<ref>Haynes, p. 4.126</ref>
	}}		}}
	| Section3 = {{Chembox Structure		|Section3={{Chembox Structure
			| Structure_ref=<ref>{{cite journal|doi=10.1063/1.1663334|title=Epitaxial PbSe and Pb<sub>1−x</sub>S<sub>x</sub>Se: Growth and electrical properties|journal=Journal of Applied Physics|volume=45|issue=2|pages=892–897|year=1974|last1=Hohnke|first1=D. K.|last2=Kaiser|first2=S. W.|bibcode=1974JAP....45..892H}}</ref>
	| CrystalStruct = ] (cubic), ]		| CrystalStruct = ] (cubic), ]
	| SpaceGroup = Fm{{overline|3}}m, No. 225		| SpaceGroup = Fm{{overline|3}}m, No. 225
			| LattConst_a = 0.62 nm
			| UnitCellFormulas = 4
			}}
			| Section4 = {{Chembox Thermochemistry
			| Thermochemistry_ref =<ref>Haynes, p. 5.5</ref>
			| HeatCapacity = 71.2 J/(mol·K)
			| Entropy = 96.4 J/(mol·K)
			| DeltaHform = −1207.1 kJ/mol
			| DeltaGfree = −1156.8 kJ/mol
			| DeltaHcombust =
			| DeltaHfus =
			| DeltaHvap =
			| DeltaHsublim =
			| HHV =
			| LHV =
	}}		}}
	| Section7 = {{Chembox Hazards		|Section7={{Chembox Hazards
			| ExternalSDS =
	| ExternalMSDS =
			| MainHazards = Toxic
	| EUClass = Harmful ('''Xn''')
			| GHSPictograms = {{GHS07}}
	| EUIndex = 056-002-00-7
	| RPhrases = {{R20/22}}
	| SPhrases = {{S2}}, {{S28}}
	| FlashPt = Non-flammable		| FlashPt = Non-flammable
	| NFPA-H = 3		| NFPA-H =
	| NFPA-F = 0		| NFPA-F =
	| NFPA-R = 0		| NFPA-R =
	| LD50 = 250 mg/kg, oral (rat)		| LD50 = 250 mg/kg, oral (rat)
	}}		}}
	| Section8 = {{Chembox Related		|Section8={{Chembox Related
	| OtherAnions = ]<br />]<br />]		| OtherAnions = {{ubl|]|]|]}}
	| OtherCations = ]<br/>]<br/>]<br/>]}}		| OtherCations = {{ubl|]|]|]|]|]}}
	}}		}}
			}}
	'''Barium fluoride''' (BaF<sub>2</sub>) is a chemical compound of ] and ]. It is a solid which can be a transparent crystal. It occurs in nature as the mineral ].<ref>{{cite journal|url=http://www.minsocam.org/ammin/AM59/AM59_885.pdf|title = Frankdicksonite, BaF2, a New Mineral from Nevada | author = Radtke A.S., Brown G.E.|journal = American Mineralogist|year = 1974|volume = 59|pages = 885–888}}</ref>
			'''Barium fluoride''' is an ] with the formula {{chem2|BaF2|auto=1}}. It is a colorless solid that occurs in nature as the rare mineral ].<ref>{{cite journal|url=http://www.minsocam.org/ammin/AM59/AM59_885.pdf|title = Frankdicksonite, BaF<sub>2</sub>, a New Mineral from Nevada | author = Radtke A.S., Brown G.E.|journal = American Mineralogist|year = 1974|volume = 59|pages = 885–888}}</ref> Under standard conditions it adopts the ] structure and at high pressure the ] structure.<ref name = "Wells">{{cite book| author = Wells, A.F. | year = 1984| title = Structural inorganic chemistry −5th Edition |location = Oxford | isbn = 0-19-855370-6| publisher = Clarendon Press}}</ref> Like ], it is resilient to and insoluble in water.
		⚫	Above ca. 500&nbsp;°C, {{chem2|BaF2}} is corroded by moisture, but in dry environments it can be used up to 800&nbsp;°C. Prolonged exposure to moisture degrades transmission in the ] range. It is less resistant to water than ], but it is the most resistant of all the optical fluorides to high-energy radiation, though its far ultraviolet transmittance is lower than that of the other fluorides. It is quite hard, very sensitive to ] and fractures quite easily.
	==Structure==
⚫	The solid adopts the ] structure and at high pressure the ] structure.<ref name = "Wells">{{cite book| author = A.F Wells | year = 1984| title = Structural inorganic chemistry -5th Edition |location = Oxford | isbn = 0-19-855370-6| publisher = Clarendon Press}}</ref> In the vapor phase the BaF<sub>2</sub> molecule is non-linear with an F-Ba-F angle of approximately 108°.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> This is an exception to ] which would predict a linear structure. Ab initio calculations have been cited to propose that contributions from d orbitals in the shell below the valence shell are responsible.<ref>{{cite journal | doi = 10.1063/1.459748 | title = Ab initio model potential study of the equilibrium geometry of alkaline earth dihalides: MX2 (M=Mg, Ca, Sr, Ba; X=F, Cl, Br, I) | year = 1991 | author = Seijo, Luis | journal = The Journal of Chemical Physics | volume = 94 | pages = 3762 | last2 = Barandiarán | first2 = Zoila | last3 = Huzinaga | first3 = Sigeru}}</ref> Another proposal is that polarisation of the electron core of the barium atom creates an approximately tetrahedral distribution of charge that interacts with the Ba-F bonds.<ref>{{cite journal| doi =10.1021/ic00113a023| title =Core Distortions and Geometries of the Difluorides and Dihydrides of Ca, Sr, and Ba| year =1995| author =Bytheway, Ian| journal =Inorganic Chemistry| volume =34| pages =2407| last2 =Gillespie| first2 =Ronald J.| last3 =Tang| first3 =Ting-Hua| last4 =Bader| first4 =Richard F. W.}}</ref>
			==Optical properties==
	==Applications==
	Barium fluoride is transparent from the ] to the ], from 150–200 ] to 11–11.5&nbsp;µm, and can be used as a material to make optical components such as lenses. It is used in windows for ], in particular in the field of fuel oil analysis. Its ] at 200&nbsp;nm is relatively low (0.60), but at 500&nbsp;nm it goes up to 0.96–0.97 and stays at that level until 9&nbsp;µm, then it starts falling off (0.85 for 10&nbsp;µm and 0.42 for 12&nbsp;µm). The refractive index is about 1.46 from 700&nbsp;nm to 5&nbsp;µm <ref>{{cite web | url=http://www.crystran.co.uk/barium-fluoride-baf2.htm |title=Crystran Ltd. Optical Component Materials |accessdate=29 December 2009}}</ref>		Barium fluoride is transparent from the ] to the ], from 150 to 200 ] to 11–11.5&nbsp;μm. It is used in windows for ], in particular in the field of fuel oil analysis. Its ] at 200&nbsp;nm is relatively low (0.60), but at 500&nbsp;nm it goes up to 0.96–0.97 and stays at that level until 9&nbsp;μm, then it starts falling off (0.85 for 10&nbsp;μm and 0.42 for 12&nbsp;μm). The refractive index is about 1.46 from 700&nbsp;nm to 5&nbsp;μm.<ref>{{cite web | url=http://www.crystran.co.uk/barium-fluoride-baf2.htm | title=Crystran Ltd. Optical Component Materials | access-date=29 December 2009 | archive-date=11 June 2010 | archive-url=https://web.archive.org/web/20100611112530/http://www.crystran.co.uk/barium-fluoride-baf2.htm | url-status=dead }}</ref>
	Barium fluoride is also a common, very fast (one of the fastest) ] for the detection of ]s, ]s or other high energy particles. One of its applications is the detection of 511 ] gamma photons in ]; other materials used in this application include ]. It responds also to alpha and beta particles, but, unlike most scintillators, it does not glow in ultraviolet light.<ref>{{cite journal| doi = 10.1016/0167-5087(83)91254-1| title = Barium fluoride – Inorganic scintillator for subnanosecond timing| year = 1983| author = Laval, M| journal = Nuclear Instruments and Methods in Physics Research| volume = 206| pages = 169}}</ref> It can be also used for detection of high-energy (10–150 MeV) ]s, and use pulse shape discrimination techniques to separate them from simultaneously occurring gamma photons.		Barium fluoride is also a common, very fast (one of the fastest) ]s for the detection of ]s, ]s or other high energy particles. One of its applications is the detection of 511 ] gamma photons in ]. It responds also to alpha and beta particles, but, unlike most scintillators, it does not emit ultraviolet light.<ref>{{cite journal| doi = 10.1016/0167-5087(83)91254-1| title = Barium fluoride – Inorganic scintillator for subnanosecond timing| year = 1983| author = Laval, M| journal = Nuclear Instruments and Methods in Physics Research| volume = 206| issue = 1–2| pages = 169–176| last2 = Moszyński| first2 = M.| last3 = Allemand| first3 = R.| last4 = Cormoreche| first4 = E.| last5 = Guinet| first5 = P.| last6 = Odru| first6 = R.| last7 = Vacher| first7 = J.| bibcode = 1983NIMPR.206..169L}}</ref> It can be also used for detection of high-energy (10–150 MeV) ]s, using pulse shape discrimination techniques to separate them from simultaneously occurring gamma photons.
⚫	When heated to 500 °C, it gets corroded by water, but in dry environment it can be used up to 800 °C. Prolonged exposure to moisture degrades transmission in the ] range. It is less resistant to water than ], but is the most resistant of all the optical fluorides to high-energy radiation, though its far ultraviolet transmittance is lower than theirs. It is quite hard, very sensitive to ] and fractures quite easily.
	Barium fluoride is used as a ] agent and in ] and glazing frits production. Its other use is in the production of ] agents (an additive to some ], a component of coatings for ]s and in welding powders). It is also used in ], as a molten bath for refining ].		Barium fluoride is used as a ] agent and in ] and glazing frits production. Its other use is in the production of ] agents (an additive to some ], a component of coatings for ]s and in welding powders). It is also used in ], as a molten bath for refining ].
			==Gas phase structure==
		⚫	In the vapor phase the {{chem2|BaF2}} molecule is non-linear with an F-Ba-F angle of approximately 108°.<ref name = "Greenwood">{{Greenwood&Earnshaw}}</ref> Its nonlinearity violates ]. Ab initio calculations indicate that contributions from d orbitals in the shell below the valence shell are responsible.<ref>{{cite journal | doi = 10.1063/1.459748 | title = Ab initio model potential study of the equilibrium geometry of alkaline earth dihalides: MX2 (M=Mg, Ca, Sr, Ba; X=F, Cl, Br, I) | year = 1991 | author = Seijo, Luis | journal = The Journal of Chemical Physics | volume = 94 | pages = 3762 | last2 = Barandiarán | first2 = Zoila | last3 = Huzinaga | first3 = Sigeru | issue = 5| url = https://repositorio.uam.es/bitstream/10486/7315/1/41581_jchemphysseijo_91_jcp_94_3762.pdf |bibcode = 1991JChPh..94.3762S|hdl = 10486/7315| hdl-access = free }}</ref> Another proposal is that polarisation of the electron core of the barium atom creates an approximately tetrahedral distribution of charge that interacts with the Ba-F bonds.<ref>{{cite journal| doi =10.1021/ic00113a023| title =Core Distortions and Geometries of the Difluorides and Dihydrides of Ca, Sr, and Ba| year =1995| author =Bytheway, Ian| journal =Inorganic Chemistry| volume =34| pages =2407| last2 =Gillespie| first2 =Ronald J.| last3 =Tang| first3 =Ting-Hua| last4 =Bader| first4 =Richard F. W.| issue =9}}</ref>
	==References==		==References==
	{{reflist}}		{{Reflist}}
			==Cited sources==
			*{{cite book | editor= Haynes, William M. | date = 2016| title = CRC Handbook of Chemistry and Physics | edition = 97th | publisher = ] | isbn = 9781498754293|page=4.49| title-link = CRC Handbook of Chemistry and Physics}}
	==External links==		==External links==
	*		* {{Webarchive|url=https://web.archive.org/web/20060517175535/http://physchem.ox.ac.uk/MSDS/BA/barium_fluoride.html |date=2006-05-17 }}
	{{Barium compounds}}		{{Barium compounds}}
			{{fluorine compounds}}
			{{Authority control}}
	{{DEFAULTSORT:Barium Fluoride}}		{{DEFAULTSORT:Barium Fluoride}}
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