Neptunium(IV) oxide

Neptunium(IV) oxide
IUPAC name Neptunium(IV) oxide
Other names Neptunium oxide, Neptunium dioxide
Identifiers
CAS number	12035-79-9
Properties
Molecular formula	NpO2
Molar mass	269 g/mol
Appearance	Green cubic crystals
Density	11.1 g/cm3
Melting point	2547 °C[1]
Structure
Crystal structure	cubic crystal system, cF12
Space group	Fm3m, #225
Coordination geometry	Np, 8, cubic O, 4, tetrahedral
Thermochemistry
Std enthalpy of formation ΔfHo298	−256.7 ± 0.6 kcal·mol-1 (−1074 ± 3 kJ·mol-1)[2]
Standard molar entropy So298	19.19 ± 0.1 cal·mol-1·K-1 (80.3 ± 0.4 J·mol-1·K-1)[3]
Related compounds
Other anions	Neptunium(III) chloride Neptunium(IV) chloride
Other cations	Uranium(VI) oxide Plutonium(IV) oxide Promethium(III) oxide
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Neptunium(IV) oxide or neptunium dioxide is the chemical compound composed of neptunium and oxygen with the formula NpO₂. It forms dark olive^[4] green cubic crystals^[1].

Uses

Metal targets which will later be irradiated by plutonium are formed of neptunium(IV) oxide.^[5].

Reactions

Neptunium(IV) oxide is formed when neptunium(IV) oxalate or neptunium(IV) peroxide is precipitated from aqueous solution and then calcined in air.^[6]

References

1. ^ ^{a b} Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). CRC Press. pp. 471. ISBN 0-84930594-2. 
2. ^ Huber, Jr., Elmer J.; Charles E. Holley, Jr. (October 1968). "Enthalpy of formation of neptunium dioxide". Journal of Chemical Engineering Data 13 (4): 545–546. doi:10.1021/je60039a029. 
3. ^ Westrum, Jr., Edgar F.; J. B. Hatcher, Darrell W. Osborne (March 1953). "The Entropy and Low Temperature Heat Capacity of Neptunium Dioxide". Journal of Chemical Physics 21 (3): 419. doi:10.1063/1.1698923. 
4. ^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill Professional. pp. 271. ISBN 0-07049439-8. http://www.google.com/books?id=0fT4wfhF1AsC&pg=PA271&dq=%22neptunium(IV)+oxide%22+OR+%22neptunium+dioxide%22&as_brr=3&ei=MaDBScOjBpK8zATZtPHGBA#PPA271,M1. Retrieved 2009-03-18. 
5. ^ Krebs, Robert E. (2006). The History and Use of our Earth's Chemical Elements. Greenwood Publishing Group. pp. 318. ISBN 978-0-31333438-2. http://www.google.com/books?id=yb9xTj72vNAC&pg=PA318&dq=%22neptunium(IV)+oxide%22+OR+%22neptunium+dioxide%22&as_brr=3&ei=MaDBScOjBpK8zATZtPHGBA. Retrieved 2009-03-18. 
6. ^ Porter, J. A. (October 1964). "Production of Neptunium Dioxide". Industrial and Engineering Chemistry Process Design and Development 3 (4): 289–292. doi:10.1021/i260012a001.