Formula Cs2O Molar mass 281.81 g/mol Appearance yellow-orange solid | Melting point 490 °C Density 4.65 g/cm³ | |
 | ||
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. Both the oxide and suboxides are brightly coloured. The species Cs2O forms yellow-orange hexagonal crystals.
Contents
Uses
Caesium oxide is used in photocathodes to detect infrared signals in devices such as image intensifiers, vacuum photodiodes, photomultipliers, and TV camera tubes 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. It is a good electron emitter; however, its high vapor pressure limits its usefulness.
Reactions
Elemental magnesium reduces caesium oxide to elemental caesium, forming magnesium oxide as a side-product:
Cs2O + Mg → 2Cs + MgOCs2O is hygroscopic, forming the corrosive CsOH on contact with water.