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 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 |
| EC Number |
|
PubChem CID
|
|
| |
| |
| 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 | |
Heat capacity (C)
|
76.0 J/(K·mol) |
Std molar
entropy (S⦵298) |
146.9 J/(K·mol) |
Std enthalpy of
formation (ΔfH⦵298) |
−345.8 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
|
Corrosive and Superbase |
| GHS labelling: | |
 
| |
| NFPA 704 (fire diamond) | |
| Flash point | non-flammable |
| Related compounds | |
Other anions
|
|
Other cations
|
|
Related compounds
|
Caesium hydroxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
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]
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]
Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product:[6][7]
Cs2O is hygroscopic, forming the corrosive CsOH on contact with water.
