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{{short description|Chemical compound}} |
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{{chembox |
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{{chembox |
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| Verifiedfields = changed |
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| verifiedrevid = 443914491 |
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| Watchedfields = changed |
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| Name = Lanthanum(III) oxide |
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| verifiedrevid = 459011566 |
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| ImageFile =La2O3structure.jpg |
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| Name = Lanthanum(III) oxide |
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| ImageFile2 = |
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| ImageFile = Oxyde de lanthane en poudre.jpg |
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| ImageName = Lanthanum(III) oxide |
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| ImageFile2 = La2O3structure.jpg |
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| IUPACName = Lanthanum(III) oxide |
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| OtherNames = Lanthanum sesquioxide<br />Lanthana |
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| ImageName = Lanthanum(III) oxide |
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| IUPACName = Lanthanum(III) oxide |
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| Section1 = {{Chembox Identifiers |
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| OtherNames = Lanthanum sesquioxide<br />Lanthana |
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| CASNo_Ref = {{cascite}} |
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| data page pagename = <!--none--> |
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|Section1={{Chembox Identifiers |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| CASNo = 1312-81-8 |
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| CASNo = 1312-81-8 |
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| RTECS = OE5330000 |
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| RTECS = OE5330000 |
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| PubChem = 150906 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/2La.3O |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = KTUFCUMIWABKDW-UHFFFAOYSA-N |
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| ChemSpiderID = 2529886 |
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| ChemSpiderID = 2529886 |
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| ChemSpiderID1 = 133008 |
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| ChemSpiderID1 = 133008 |
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| ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}} |
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| UNII = 4QI5EL790W |
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| EINECS = 215-200-5 |
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| StdInChI=1S/2La.3O/q2*+3;3*-2 |
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| StdInChIKey = MRELNEQAGSRDBK-UHFFFAOYSA-N |
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| SMILES = .... |
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}} |
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}} |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| La=2|O=3 |
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| Formula = La<sub>2</sub>O<sub>3</sub> |
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| Appearance = White powder, ] |
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| MolarMass = 325.81 g/mol |
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| Density = 6.51 g/cm<sup>3</sup>, solid |
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| Appearance = White powder, ] |
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| Solubility = Insoluble |
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| Density = 6.51 g/cm<sup>3</sup>, solid |
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| MeltingPtC = 2315 |
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| Solubility = Insoluble |
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| MeltingPt_notes = |
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| MeltingPt = 2315 °C (2588 K) |
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| BoilingPt = 4200 °C (4500 K) |
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| BoilingPtC = 4200 |
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| BoilingPt_notes = |
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| BandGap = 4.3 eV |
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| BandGap = 4.3 eV |
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| MagSus = −78.0·10<sup>−6</sup> cm<sup>3</sup>/mol |
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}} |
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| Section3 = {{Chembox Structure |
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|Section3={{Chembox Structure |
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| CrystalStruct = Hexagonal, ] |
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| CrystalStruct = Hexagonal, ] |
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| SpaceGroup = P-3m1, No. 164 |
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| SpaceGroup = P-3m1, No. 164 |
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}} |
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}} |
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| Section7 = {{Chembox Hazards |
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|Section7={{Chembox Hazards |
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| ExternalSDS = |
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| ExternalMSDS = |
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| GHSPictograms = {{GHS07}}<ref name=sds>{{cite web|title = Lanthanum Oxide|url = https://www.americanelements.com/lanthanum-oxide-1312-81-8|publisher = ]|access-date = October 26, 2018}}</ref> |
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| MainHazards = Irritant |
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| GHSSignalWord = Warning<ref name=sds /> |
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| NFPA-H = 1 |
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| HPhrases = {{H-phrases|315|319|335}}<ref name=sds /> |
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| NFPA-F = |
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| PPhrases = {{P-phrases|261|280|301+310|304+340|305+351+338|405|501}}<ref name=sds /> |
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| NFPA-R = 1 |
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| MainHazards = Irritant |
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| NFPA-O=<s>W</s> |
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| NFPA-H = 1 |
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| FlashPt = Non-flammable |
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| NFPA-F = |
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| RPhrases = {{R36/37}} |
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| NFPA-R = |
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| SPhrases = {{S26}}, {{S22}}, {{S37/39}} |
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| NFPA-S =W |
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| FlashPt = Non-flammable |
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}} |
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}} |
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| Section8 = {{Chembox Related |
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|Section8={{Chembox Related |
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| OtherAnions = ] |
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| OtherCations = ]<br>]<br>] |
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| OtherCpds = ],<br />LaSrCoO<sub>4</sub> |
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| OtherCations = ]<br>] |
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| OtherCompounds = ],<br />LaSrCoO<sub>4</sub> |
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'''Lanthanum oxide''' is La<sub>2</sub>O<sub>3</sub>, an ] containing the ] ] and ]. It is used to develop ferroelectric materials, and in optical materials. |
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'''Lanthanum(III) oxide''', also known as '''lanthana''', chemical formula {{chem2|La2O3}}, is an ] containing the ] ] and ]. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock for certain catalysts, among other uses. |
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==Properties== |
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==Properties== |
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Lanthanum oxide is a white solid that is insoluble in water, but dissolves in acidic solutions. {{chem2|La2O3}} absorbs moisture from air, converting to lanthanum hydroxide.<ref name=G&E>{{Greenwood&Earnshaw2nd}}</ref> |
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La<sub>2</sub>O<sub>3</sub> has largest ] of the rare earth oxides at 4.3 eV, while also having the lowest lattice energy, with very high ], ε = 27. La<sub>2</sub>O<sub>3</sub> is widely used in industry as well as in the research laboratory. Lanthanum oxide is an odorless, white solid that is insoluble in water, but soluble in dilute acid. Depending on the pH of the compound, different crystal structures can be obtained. La<sub>2</sub>O<sub>3</sub> is hygroscopic; Under atmosphere, lanthanum oxide absorbs moisture over time and converts to lanthanum hydroxide. Lanthanum oxide has p-type semi-conducting properties because its resistivity decreases with an increase in temperature, average room temperature resistivity is 10 kΩ·cm. |
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Lanthanum oxide has p-type semiconducting properties and a band gap of approximately 5.8 eV.<ref>{{cite journal | last1 = Shang | first1 = G. | last2 = Peacock | first2 = P. W. | last3 = Robertson | first3 = J. | year = 2004| title = Stability and band offsets of nitrogenated high-dielectric-constant gate oxides | journal = Applied Physics Letters | volume = 84 | issue = 1| pages = 106–108 | doi = 10.1063/1.1638896 | bibcode = 2004ApPhL..84..106S }}</ref> Its average room temperature resistivity is 10 kΩ·cm, which decreases with an increase in temperature. {{chem2|La2O3}} has the lowest lattice energy of the rare earth oxides, with very high ] ε = 27. |
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==Structure== |
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==Structure== |
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At low temperatures, La<sub>2</sub>O<sub>3</sub> has an A-M<sub>2</sub>O<sub>3</sub> hexagonal crystal structure. The La<sup>3+</sup> metal atoms are surrounded by a 7 coordinate group of O<sup>2-</sup>atoms, the oxygen ions are in an octahedral shape around the metal atom and there is one oxygen ion above one of the octahedral faces.<ref>{{cite book| author = Wells, A.F. | title = Structural Inorganic Chemistry|location = Oxford| publisher = Clarendon Press| year = 1984| page = 546}}</ref> On the other hand, at high temperatures the Lanthanum oxide converts to a C-M<sub>2</sub>O<sub>3</sub> cubic crystal structure. The La<sup>3+</sup> ion is surrounded by a 6 coordinate group of O<sup>2-</sup> ions.<ref>{{cite book| author = Wyckoff, R. W.G. | title = Crystal Structures: Inorganic Compounds RXn, RnMX2, RnMX3| location = New York| publisher = Interscience Publishers | year =1963}}</ref> |
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At low temperatures, {{chem2|La2O3}} has an A-{{chem2|M2O3}} hexagonal crystal structure. The {{chem2|La(3+)}} metal atoms are surrounded by a 7 coordinate group of {{chem2|O(2−)}} atoms, the oxygen ions are in an octahedral shape around the metal atom and there is one oxygen ion above one of the octahedral faces.<ref>{{cite book| author = Wells, A.F. | title = Structural Inorganic Chemistry|location = Oxford| publisher = Clarendon Press| year = 1984| page = 546}}</ref> On the other hand, at high temperatures lanthanum oxide converts to a C-{{chem2|M2O3}} cubic crystal structure. The {{chem2|La(3+)}} ion is surrounded by six {{chem2|O(2−)}} ions in a hexagonal configuration.<ref>{{cite book| author = Wyckoff, R. W.G. | title = Crystal Structures: Inorganic Compounds RXn, RnMX2, RnMX3| location = New York| publisher = Interscience Publishers | year =1963}}</ref><ref>{{cite journal |doi=10.1021/cr940055h|title=The Binary Rare Earth Oxides |year=1998 |last1=Adachi |first1=Gin-ya |last2=Imanaka |first2=Nobuhito |journal=Chemical Reviews |volume=98 |issue=4 |pages=1479–1514 |pmid=11848940 }}</ref> |
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==Synthesis== |
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==Synthesis== |
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lanthanum oxide crystallizes as several ]s. |
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Lanthanum oxide can crystallize in at least three ]s.<ref name=G&E/> |
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To produce hexagonal La<sub>2</sub>O<sub>3</sub>, a 0.1 M solution of LaCl<sub>3</sub> is sprayed onto a preheated substrate, usually made of metal chalcogenides.<ref name=kale>{{cite journal|doi=10.1016/j.matlet.2005.02.091|title=Characterizations of spray-deposited lanthanum oxide (La2O3) thin films|year=2005|author=Kale, S.S.; Jadhav, K.R.; Patil, P.S.; Gujar, T.P.; Lokhande, C.D.|journal=Materials Letters|volume=59|pages=3007}}</ref> The process can be viewed as occurring in two steps – hydrolysis followed by dehydration: |
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Hexagonal {{chem2|La2O3}} has been produced by spray pyrolysis of lanthanum chloride.<ref name=kale>{{cite journal|doi=10.1016/j.matlet.2005.02.091|title=Characterizations of spray-deposited lanthanum oxide (La2O3) thin films|year=2005|author1=Kale, S.S. |author2=Jadhav, K.R. |author3=Patil, P.S. |author4=Gujar, T.P. |author5=Lokhande, C.D. |journal=Materials Letters|volume=59|issue=24–25|pages=3007–3009}}</ref> |
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:{{chem2|2 LaCl3 + 3 H2O → La(OH)3 + 3 HCl}} |
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:{{chem2|2 La(OH)3 → La2O3 + 3 H2O}} |
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An alternative route to obtaining hexagonal {{chem2|La2O3}} involves precipitation of nominal {{chem2|La(OH)3}} from aqueous solution using a combination of 2.5% {{chem2|NH3}} and the surfactant ] followed by heating and stirring for 24 hours at 80 °C: |
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:2 LaCl<sub>3</sub> + 3 H<sub>2</sub>O → La(OH)<sub>3</sub> + 3 HCl |
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:{{chem2|2 LaCl3 + 3 H2O + 3 NH3 → La(OH)3 + 3 Cl}} |
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:2 La(OH)<sub>3</sub> → La<sub>2</sub>O<sub>3</sub> + 3 H<sub>2</sub>O |
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Other routes include: |
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An alternative route to hexagonal La<sub>2</sub>O<sub>3</sub> involves precipitation of nominal La(OH)<sub>3</sub> from aqueous solution using a combination of 2.5% NH<sub>3</sub> and the surfactant ] followed by heating and stirring for 24 hours at 80°C: |
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:{{chem2|2 La2S3 + 3 CO2 → 2 La2O3 + 3 CS2}} |
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:2 LaCl<sub>3</sub>+ 3 H<sub>2</sub>O + 3 NH<sub>3</sub> → La(OH)<sub>3</sub> + 3 NH<sub>4</sub>Cl |
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:LaCl<sub>3</sub>·3H<sub>2</sub>O → La<sub>2</sub>O<sub>3</sub> |
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Other routes include: |
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:2 La<sub>2</sub>S<sub>3</sub> + 3 CO<sub>2</sub> → 2 La<sub>2</sub>O<sub>3</sub> + 3 CS<sub>2</sub> |
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:2 La<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> + heat → 2 La<sub>2</sub>O<sub>3</sub> + 6 SO<sub>3</sub> |
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==Reactions== |
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==Reactions== |
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Lanthanum oxide is used to develop ferroelectric materials, such as La-doped Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub> (BLT). |
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Lanthanum oxide is used as an additive to develop certain ferroelectric materials, such as La-doped ] ({{chem2|Bi4Ti3O12}} - BLT). |
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Lanthanum oxide is used in optical materials, often the optical glasses are doped with La<sub>2</sub>O<sub>3</sub> to improve the glass' refractive index, chemical durability, and mechanical strength. |
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Lanthanum oxide is used in optical materials; often the optical glasses are doped with {{chem2|La2O3}} to improve the glass' refractive index, chemical durability, and mechanical strength.<ref>{{cite journal|doi=10.1023/B:GPAC.0000016391.83527.44|title=Glass Transition and Crystallization of Glasses Based on Rare-Earth Borates|year=2004|author1=Vinogradova, N. N. |author2=Dmitruk, L. N. |author3=Petrova, O. B. |journal=Glass Physics and Chemistry|volume=30|pages=1–5|s2cid=94177915 }}</ref> |
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:{{chem2|3 B2O3 + La2O3 → 2 La(BO2)3}}{{Clarification needed|What this reaction stands for?|date=July 2022}} |
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:3 B<sub>2</sub>O<sub>3</sub> + La<sub>2</sub>O<sub>3</sub> → 2 La(BO<sub>2</sub>)<sub>3</sub> |
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When this 1:3 reaction is mixed into a glass composite, the high molecular weight of the lanthanum causes an increase of the homogeneous mixture of the melt which leads to a lower melting point.<ref>{{cite journal|doi=10.1023/B:GPAC.0000016391.83527.44|title=Glass Transition and Crystallization of Glasses Based on Rare-Earth Borates|year=2004|author=Vinogradova, N. N.; Dmitruk, L. N.; Petrova, O. B.|journal=Glass Physics and Chemistry|volume=30|pages=1}}</ref> The addition of the La<sub>2</sub>O<sub>3</sub> to the glass melt leads to a higher glass transition temperature from 658 °C to 679 °C. The addition also leads to a higher density, microhardness, and refractive index of the glass. |
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The addition of the {{chem2|La2O3}} to the glass melt leads to a higher glass transition temperature from 658 °C to 679 °C. The addition also leads to a higher density, microhardness, and refractive index of the glass. |
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==Uses and applications== |
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==Potential applications== |
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Lanthanum oxide is most useful as a precursor to other lanthanum compounds.<ref>"Lanthanum has also found modest uses." {{Greenwood&Earnshaw2nd|page=946}}</ref> Neither the oxide nor any of the derived materials enjoys substantial commercial value, unlike some of the other lanthanides. Many reports describe efforts toward practical applications of {{chem2|La2O3}}, as described below. |
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La<sub>2</sub>O<sub>3</sub> is used to make optical glasses, to which this oxide confers increased density, refractive index, and hardness. Together with oxides of ], ], and ], La<sub>2</sub>O<sub>3</sub> improves the resistance of the glass to attack by alkali. La<sub>2</sub>O<sub>3</sub> is an ingredient for the manufacture of ] and thermoelectric materials. Automobile exhaust-gas converters contain La<sub>2</sub>O<sub>3</sub>.<ref>{{cite journal|doi=10.1016/j.matlet.2004.09.034|title=Controllable syntheses of hexagonal and lamellar mesostructured lanthanum oxide|year=2005|author=Cao, J; Ji, H; Liu, J; Zheng, M; Chang, X; Ma, X; Zhang, A; Xu, Q|journal=Materials Letters|volume=59|pages=408 }}</ref> La<sub>2</sub>O<sub>3</sub> is also used in X-ray imaging intensifying screens, phophors as well as dielectric and conductive ceramics. |
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{{chem2|La2O3}}{{anchor|lanthanum_glass_anchor}} forms glasses of high density, refractive index, and hardness. Together with oxides of ], ], and ], {{chem2|La2O3}} improves the resistance of the glass to attack by alkali. {{chem2|La2O3}} is an ingredient in some ] and thermoelectric materials.<!-- untrue, that is cerium: Automobile exhaust-gas converters contain {{chem2|La2O3}}.<ref>{{cite journal |author1=Cao, J. |author2=Ji, H. |author3=Liu, J. |author4=Zheng, M. |author5=Chang, X. |author6=Ma, X. |author7=Zhang, A. |author8=Xu, Q. |year=2005 |title=Controllable syntheses of hexagonal and lamellar mesostructured lanthanum oxide |journal=Materials Letters |volume=59 |issue=4 |pages=408–411 |doi=10.1016/j.matlet.2004.09.034}}</ref> {{chem2|La2O3}} is also used in X-ray imaging intensifying screens, phosphors as well as dielectric and conductive ceramics. Gives off bright glow. |
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La<sub>2</sub>O<sub>3</sub> has been examined for the ].<ref> {{cite journal|doi=10.1021/jp040311m| title=Surface Acidity and Basicity of La2O3, LaOCl, and LaCl3 Characterized by IR Spectroscopy, TPD, and DFT Calculations|author= O.V. Manoilova ''et al.''| journal=J. Phys. Chem. B| year = 2004| volume = 108 | page =15770}}</ref> |
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{{chem2|La2O3}} films can be ] by many different methods, including ], ], ], ], and ]. Depositions of these films occur in a temperature range of 250–450 °C. ] films are formed at 350 °C.<ref name=kale/> |
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{{chem2|La2O3}} tungsten electrodes are replacing thoriated tungsten electrodes in ] due to safety concerns with thorium's radioactivity. |
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La<sub>2</sub>O<sub>3</sub> films can be ] by many different methods, including: ], ], ], and ]. Depositions of these films occur in a temperature range of 250–450 °C. ] films are formed at 350 °C.<ref name=kale/> |
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{{chem2|La2O3}} has been examined for the ].<ref>{{cite journal |author1=Manoilova, O.V. |display-authors=etal |year=2004 |title=Surface acidity and basicity of La2O3, LaOCl, and LaCl3 characterized by IR spectroscopy, TPD, and DFT calculations |journal=J. Phys. Chem. B |volume=108 |issue=40 |pages=15770–15781 |doi=10.1021/jp040311m}}</ref> |
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==References== |
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==References== |
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{{reflist}} |
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{{reflist}} |
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<!--* Bedoya, C. "MOCVD of Lanthanum Oxides from La(tmhd)3 and La(tmod)3 Precursors: A Thermal and Kinetic Investigation." Chemical Vapor Deposition. 12 (2006): 46-53. |
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* Imanaka, Nobuhito. "Preparation of the cubic-type La2O3 phase by thermal decomposition of LaI3." Journal of Solid State Chemistry. 178 (2005): 395–398. |
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* "Lanthanum oxide." The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biological. 11th ed. 1989. |
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* Veldurthy, B. "Magnesium-Lanthanum Mixed Metal Oxide: A Strong Solid Base for the Michael Addition Reaction." Adv. Synth. Catal. 347 (2005): 767–771. |
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*"Lanthanum oxide." Encyclopedia of Chemical Reactions. 1951.--> |
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==External links== |
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* http://www.chemsoc.org/viselements/pages/data/lanthanum_data.html |
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{{Lanthanum compounds}} |
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{{Lanthanum compounds}} |
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{{Oxides}} |
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{{DEFAULTSORT:Lanthanum(Iii) Oxide}} |
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{{DEFAULTSORT:Lanthanum(Iii) Oxide}} |
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