Caesium oxide[1][2] | |
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Caesium oxide |
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Other names
Cesium oxide (US) |
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Identifiers | |
CAS number | 20281-00-9 |
PubChem | 9903865 |
ChemSpider | 8079519 |
EC-number | 243-679-0 |
Jmol-3D images | Image 1 |
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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 |
Structure | |
Crystal structure | anti-CdCl2 (hexagonal) |
Thermochemistry | |
Std enthalpy of formation ΔfH |
-345.8 kJ/mol |
Standard molar entropy S |
146.9 J K-1 mol-1 |
Specific heat capacity, C | 76.0 J K-1 mol-1 |
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 |
(verify) (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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]
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]
Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product:[7][8]
Cs2O is hygroscopic, forming the corrosive CsOH on contact with water.
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