Caesium monoxide

Chemical compound From Wikipedia, the free encyclopedia

Caesium monoxide or caesium oxide is a chemical compound with the chemical formula Cs2O. It is the simplest and most common oxide of the caesium. It forms yellow-orange hexagonal crystals.[1]

Quick facts Names, Identifiers ...
Caesium oxide[1][2]
Caesium oxide
Caesium oxide
  Caesium cations, Cs+
  Oxide anions, O2−
Names
IUPAC name
Caesium oxide
Other names
Cesium oxide (US)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.039.693 Edit this at Wikidata
EC Number
  • 243-679-0
  • InChI=1S/2Cs.O/q2*+1;-2 checkY
    Key: KOPBYBDAPCDYFK-UHFFFAOYSA-N checkY
  • InChI=1/2Cs.O/q2*+1;-2
    Key: KOPBYBDAPCDYFK-UHFFFAOYAW
  • [Cs+].[Cs+].[O-2]
Properties
Cs2O
Molar mass 281.810 g·mol−1
Appearance Yellow-orange solid
Density 4.65 g/cm3, solid
Melting point 490 °C (914 °F; 763 K) (under N2)
Reacts to form CsOH
1534.0·10−6 cm3/mol
Structure
anti-CdCl2 (hexagonal)
Thermochemistry
76.0 J/(K·mol)
146.9 J/(K·mol)
−345.8 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Corrosive and Superbase
GHS labelling:
GHS05: CorrosiveGHS08: Health hazard
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
0
2
W
Flash point non-flammable
Related compounds
Other anions
Other cations
Related caesium oxides
Related compounds
 Caesium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Uses

Caesium oxide is used in photocathodes to detect infrared signals in devices such as image intensifiers, vacuum photodiodes, photomultipliers, and TV camera tubes[3] L. R. Koller described the first modern photoemissive surface in 1929–1930 as a layer of caesium on a layer of caesium oxide on a layer of silver.[4] It is a good electron emitter; however, its high vapor pressure limits its usefulness.[5]

Reactions

Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product:[6][7]

Cs2O + Mg → 2 Cs + MgO

Cs2O is hygroscopic, forming the corrosive CsOH on contact with water.

References

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