Caesium oxide
| Caesium oxide | |
|---|---|
| |
| IUPAC name | Caesium oxide |
| Identifiers | |
| InChI | InChI=1/2Cs.O/q2*+1;-2 |
| InChIKey | KOPBYBDAPCDYFK-UHFFFAOYAW |
| Standard InChI | InChI=1S/2Cs.O/q2*+1;-2 |
| Standard InChIKey | KOPBYBDAPCDYFK-UHFFFAOYSA-N |
| CAS number | [] |
| EC number | |
| ChemSpider | |
| Properties[1] | |
| Chemical formula | Cs2O |
| Molar mass | 281.81 g/mol |
| Appearance | yellow-orange solid |
| Density | 4.25 g/cm3, solid |
| Melting point |
490 °C (under N2) |
| Solubility in water | reacts |
| Structure[2] | |
| Crystal structure | anti-CdCl2 (hexagonal) |
| Coordination geometry | Octahedral (O2-) |
| 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 number | 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, 100 kPa) | |
Caesium oxide is one of several binary compounds of caesium and oxygen. It has the formula Cs2O, and forms yellow-orange hexagonal crystals.[1]
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 1929–30 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:[6][7]
- Cs2O + Mg → 2Cs + MgO
When heated in air, caesium oxide decomposes at around 400 ºC, before it melts: its melting point (490 ºC) must be determined under an atomsphere of nitrogen.[1]
References
- ↑ 1.0 1.1 1.2 CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-92. ISBN 0-8493-0462-8.
- ↑ Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; pp 97–100. ISBN 0-08-022057-6.
- ↑ Capper, Peter; Elliott, C. T. Infrared Detectors and Emitters; Springer, 2000; p 14. ISBN 9780792372066
- ↑ Busch, Kenneth W.; Busch, Marianna A. Multielement Detection Systems for Spectrochemical Analysis; Wiley-Interscience, 1990; p 12. ISBN 9780471819745
- ↑ Insulating and Semiconducting Glasses; Boolchand, Punit, Ed.; World Scientific, 2000; p 855. ISBN 9789810236731
- ↑ The Condensed Chemical Dictionary; Turner, Jr., Francis M., Ed.; Chemical Catalog Co.: New York, 1920; p 121
- ↑ Arora, M.G. S-Block Elements; Anmol: New Delhi, 1997; p 13. ISBN 9788174885623
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