Caesium oxide

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Caesium oxide[1][2]
Caesium oxide
Identifiers
CAS number 20281-00-9 YesY
PubChem 9903865
ChemSpider 8079519 YesY
EC-number 243-679-0
Jmol-3D images Image 1
Properties
Molecular formula Cs2O
Molar mass 281.81 g/mol
Appearance yellow-orange solid
Density 4.65 g/cm3, solid
Melting point 490 °C (under N2)
Solubility in water reacts violently to form CsOH
Structure
Crystal structure anti-CdCl2 (hexagonal)
Thermochemistry
Specific
heat capacity
C
76.0 J K-1 mol-1
Std molar
entropy
So298
146.9 J K-1 mol-1
Std enthalpy of
formation
ΔfHo298
-345.8 kJ/mol
Hazards
EU Index not listed
Flash point non-flammable
Related compounds
Other anions Caesium hydroxide
Other cations Lithium oxide
Sodium oxide
Potassium oxide
Rubidium oxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Caesium oxide (IUPAC name) or cesium oxide describes inorganic compounds composed of caesium and oxygen. The following binary (containing only Cs and O) oxides of caesium are known: Cs11O3, Cs4O, Cs7O, and Cs2O.[3] Both the oxide and suboxides are brightly coloured. The species Cs2O forms yellow-orange hexagonal crystals.[1]

Uses[edit]

Caesium oxide is used in photocathodes to detect infrared signals in devices such as image intensifiers, vacuum photodiodes, photomultipliers, and TV camera tubes[4] L. R. Koller described the first modern photoemissive surface in 1929–30 as a layer of caesium on a layer of caesium oxide on a layer of silver.[5] It is a good electron emitter; however, its high vapor pressure limits its usefulness.[6]

Reactions[edit]

Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product:[7][8]

Cs2O + Mg → 2Cs + MgO

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

References[edit]

  1. ^ a b Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. pp. 451, 514. ISBN 0-8493-0487-3. .
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. pp. 97–100. ISBN 0-08-022057-6. .
  3. ^ Simon, A. (1997), "Group 1 and 2 Suboxides and Subnitrides — Metals with Atomic Size Holes and Tunnels", Coord. Chem. Rev. 163: 253–270, doi:10.1016/S0010-8545(97)00013-1 .
  4. ^ Capper, Peter; Elliott, C. T. (2000), Infrared Detectors and Emitters, Springer, p. 14, ISBN 978-0-7923-7206-6 
  5. ^ Busch, Kenneth W.; Busch, Marianna A. (1990), Multielement Detection Systems for Spectrochemical Analysis, Wiley-Interscience, p. 12, ISBN 978-0-471-81974-5 
  6. ^ Boolchand, Punit, ed. (2000), Insulating and Semiconducting Glasses, World Scientific, p. 855, ISBN 978-981-02-3673-1 
  7. ^ Turner, Jr., Francis M., ed. (1920), The Condensed Chemical Dictionary, New York: Chemical Catalog Co., p. 121 
  8. ^ Arora, M.G. (1997), S-Block Elements, New Delhi: Anmol Publications, p. 13, ISBN 978-81-7488-562-3