Lithium oxide
{{use dmy dates|date=May 2022|cs1-dates=y}}
{{distinguish|Lithium superoxide}}
{{Chembox
| Watchedfields = changed
| verifiedrevid = 415682145
| Name = Lithium oxide
| ImageFile = Lithium-oxide-unit-cell-3D-balls-B.png
| ImageSize = 135px
| ImageFile1 = Lithium-oxide-unit-cell-3D-ionic.png
| ImageSize1 = 135px
| ImageFile2 = CaF2 polyhedra.png
| ImageCaption2 = __ Li+ __ O2−
| ImageFile3 = Li2O.jpg
| IUPACName = Lithium oxide
| OtherNames = Lithia
Kickerite
Dilithium Monoxide
Dilithium Oxide
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 145811
| InChI = 1S/2Li.O/q2*+1;-2
| InChIKey = FUJCRWPEOMXPAD-UHFFFAOYAW
| SMILES = [Li+].[Li+].[O-2]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2Li.O/q2*+1;-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = FUJCRWPEOMXPAD-UHFFFAOYSA-N
| InChIKey1 = FUJCRWPEOMXPAD-UHFFFAOYSA-N
| CASNo = 12057-24-8
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 2ON0O9YI0Q
| EINECS =
| PubChem = 166630
| RTECS = OJ6360000
}}
| Section2 = {{Chembox Properties
| Formula = {{chem|Li|2|O}}
| MolarMass = 29.88 g/mol
| Appearance = white or pale yellow solid
| Density = 2.013 g/cm3
| MeltingPtC = 1438
| BoilingPtC = 2600
| Solubility = Reacts to form LiOH
| SolubleOther =
| Solvent =
| LogP = 9.23
| RefractIndex = 1.644 Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}
}}
| Section3 = {{Chembox Structure
| CrystalStruct = Antifluorite (cubic), cF12
| SpaceGroup = Fm3m, No. 225
| Coordination = Tetrahedral (Li+); cubic (O2−)
| LattConst_a =
| LattConst_alpha =
}}
| Section4 = {{Chembox Thermochemistry
| DeltaHf = −20.01 kJ/g or −595.8 kJ/mol
| DeltaGf = −562.1 kJ/mol
| Entropy = 37.89 J/mol K
| HeatCapacity = 1.8105 J/g K or 54.1 J/mol K
}}
| Section5 =
| Section6 =
| Section7 = {{Chembox Hazards
| ExternalSDS =
| MainHazards = Corrosive, reacts violently with water
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 1
| NFPA-S = W
| FlashPt = Non-flammable
| PEL =
}}
| Section8 = {{Chembox Related
| OtherAnions = Lithium sulfide
Lithium selenide
Lithium telluride
Lithium polonide
| OtherCations = Sodium oxide
Potassium oxide
Rubidium oxide
Caesium oxide
| OtherFunction = Lithium peroxide
Lithium superoxide
| OtherFunction_label = lithium oxides
| OtherCompounds = Lithium hydroxide
}}
}}
Lithium oxide (LithiumO) or lithia is an inorganic chemical compound. It is a white or pale yellow solid. Although not specifically important, many materials are assessed on the basis of their Li2O content. For example, the Li2O content of the principal lithium mineral spodumene (LiAlSi2O6) is 8.03%.
Production
Lithium oxide forms along with small amounts of lithium peroxide when lithium metal is burned in the air and combines with oxygen at temperatures above 100 °C:{{Greenwood&Earnshaw1st|pages=97–99}}
:4Li + {{chem|O|2}} → 2{{chem|Li|2|O}}.
Pure {{chem|Li|2|O}} can be produced by the thermal decomposition of lithium peroxide, {{chem|Li|2|O|2}}, at 450 °CWietelmann, Ulrich and Bauer, Richard J. (2005) "Lithium and Lithium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH: Weinheim. {{doi|10.1002/14356007.a15_393}}.
:2{{chem|Li|2|O|2}} → 2{{chem|Li|2|O}} + {{chem|O|2}}
Structure
Solid lithium oxide adopts an antifluorite structure with four-coordinated Li+ centers and eight-coordinated oxides.{{Cite journal |title=Gitterstruktur der Oxyde, Sulfide, Selenide und Telluride des Lithiums, Natriums und Kaliums |language=de |journal=Zeitschrift für Elektrochemie und Angewandte Physikalische Chemie |date=1934 |volume=40 |pages=588–593 |author-first1=Eduard |author-last1=Zintl |author-link1=Eduard Zintl |author-first2=A. |author-last2=Harder |author-first3=B. |author-last3=Dauth |issue=8 |doi=10.1002/bbpc.19340400811|s2cid=94213844 }}
The ground state gas phase {{chem|Li|2|O}} molecule is linear with a bond length consistent with strong ionic bonding.Wells A. F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications {{ISBN|0-19-855370-6}}A spectroscopic determination of the bond length of the LiOLi molecule: Strong ionic bonding, D. Bellert, W. H. Breckenridge, J. Chem. Phys. 114, 2871 (2001); {{doi|10.1063/1.1349424}} VSEPR theory would predict a bent shape similar to {{chem|H|2|O}}.
Uses
Lithium oxide is used as a flux in ceramic glazes; and creates blues with copper and pinks with cobalt. Lithium oxide reacts with water and steam, forming lithium hydroxide and should be isolated from them.
Its usage is also being investigated for non-destructive emission spectroscopy evaluation and degradation monitoring within thermal barrier coating systems. It can be added as a co-dopant with yttria in the zirconia ceramic top coat, without a large decrease in expected service life of the coating. At high heat, lithium oxide emits a very detectable spectral pattern, which increases in intensity along with degradation of the coating. Implementation would allow in situ monitoring of such systems, enabling an efficient means to predict lifetime until failure or necessary maintenance.
Lithium metal might be obtained from lithium oxide by electrolysis, releasing oxygen as by-product.
Reactions
Lithium oxide absorbs carbon dioxide forming lithium carbonate:
:{{chem|Li|2|O}} + {{chem|C|O|2}} → {{chem|Li|2|C|O|3}}
The oxide reacts slowly with water, forming lithium hydroxide:
:{{chem|Li|2|O}} + {{chem|H|2|O}} → 2{{chem|Li|O|H}}
See also
References
{{reflist}}
External links
- [https://web.archive.org/web/20060521163250/http://www.ceramic-materials.com/cermat/oxide/li2o.html CeramicMaterials.Info entry]
{{Lithium compounds}}
{{Oxides}}
{{oxygen compounds}}