Lithium oxide

Lithium oxide

__ Li+     __ O2−
Names
IUPAC name Lithium oxide
Other names Lithia Kickerite Dilithium Monoxide Dilithium Oxide
Identifiers
CAS Number	12057-24-8 Y
3D model (JSmol)	Interactive image
ChemSpider	145811 Y
ECHA InfoCard	100.031.823
PubChem CID	166630
RTECS number	OJ6360000
UNII	2ON0O9YI0Q Y
CompTox Dashboard (EPA)	DTXSID90923799 DTXSID10893208, DTXSID90923799
InChI InChI=1S/2Li.O/q2*+1;-2 Y Key: FUJCRWPEOMXPAD-UHFFFAOYSA-N Y InChI=1S/2Li.O/q2*+1;-2 Key: FUJCRWPEOMXPAD-UHFFFAOYAW Key: FUJCRWPEOMXPAD-UHFFFAOYSA-N
SMILES [Li+].[Li+].[O-2]
Properties
Chemical formula	Li 2O
Molar mass	29.88 g/mol
Appearance	white or pale yellow solid
Density	2.013 g/cm3
Melting point	1,438 °C (2,620 °F; 1,711 K)
Boiling point	2,600 °C (4,710 °F; 2,870 K)
Solubility in water	Reacts to form LiOH
log P	9.23
Refractive index (nD)	1.644 [1]
Structure
Crystal structure	Antifluorite (cubic), cF12
Space group	Fm3m, No. 225
Coordination geometry	Tetrahedral (Li+); cubic (O2−)
Thermochemistry
Heat capacity (C)	1.8105 J/g K or 54.1 J/mol K
Std molar entropy (S⦵298)	37.89 J/mol K
Std enthalpy of formation (ΔfH⦵298)	−20.01 kJ/g or −595.8 kJ/mol
Gibbs free energy (ΔfG⦵)	−562.1 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive, reacts violently with water
NFPA 704 (fire diamond)	3 0 1 W
Flash point	Non-flammable
Related compounds
Other anions	Lithium sulfide Lithium selenide Lithium telluride Lithium polonide
Other cations	Sodium oxide Potassium oxide Rubidium oxide Caesium oxide
Related lithium oxides	Lithium peroxide Lithium superoxide
Related compounds	Lithium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Lithium oxide (Li
₂O) 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%.^[2]

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:^[3]

4Li + O
₂ → 2Li
₂O.

Pure Li
₂O can be produced by the thermal decomposition of lithium peroxide, Li
₂O
₂, at 450 °C^[3][2]

2Li
₂O
₂ → 2Li
₂O + O
₂

Solid lithium oxide adopts an antifluorite structure with four-coordinated Li+ centers and eight-coordinated oxides.^[4]

The ground state gas phase Li
₂O molecule is linear with a bond length consistent with strong ionic bonding.^[5][6] VSEPR theory would predict a bent shape similar to H
₂O.

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.

Lithium oxide absorbs carbon dioxide forming lithium carbonate:

Li
₂O + CO
₂ → Li
₂CO
₃

The oxide reacts slowly with water, forming lithium hydroxide:

Li
₂O + H
₂O → 2LiOH

• Lithium monoxide anion
• Lithium peroxide
• Lithium cobalt oxide
• Lithium-oxide memristor

• CeramicMaterials.Info entry