Plutonium(IV) oxide
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| Plutonium (IV) Oxide | |
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| IUPAC name | Plutonium(IV) oxide |
| Other names | Plutonium dioxide |
| Identifiers | |
| CAS number | [12059-95-9] |
| RTECS number | na |
| Properties | |
| Molecular formula | O2Pu |
| Molar mass | 276.063 g/mol |
| Appearance | Yellow-brown crystalline solid. |
| Density | 11.5 g/cm³, solid |
| Melting point |
2400 °C (2673.15 K) |
| Boiling point |
2800 °C (3073.15 K) |
| Solubility in water | insoluble |
| Structure | |
| Crystal structure | Cubic |
| Coordination geometry |
8-coordinate Pu |
| Hazards | |
| Main hazards | Radioactive, highly toxic |
| Flash point | Non-flammable |
| Related compounds | |
| Related compounds | UO2, CaF2 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Plutonium(IV) oxide is the chemical compound with the formula PuO2. This high melting point, yellow-brown, solid is a principal compound of plutonium.
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[edit] Structure
PuO2 crystallizes in the fluorite motif, with the Pu4+ centers organized in a face-centered cubic array. Oxide ions occupying tetrahedral holes. PuO2 owes utility as a nuclear fuel to the fact that vacancies in the octahedral holes allows room for fissile products. In nuclear fission, one atom of plutonium splits into two. The vacancy of the octahedral holes provides room for the new product and allows the PuO2 monolith to retain its structural integrity.
[edit] Synthesis
Plutonium metal spontaneously oxidizes to PuO2 in an atmosphere of oxygen. Plutonium dioxide is mainly produced by calcination of plutonium(IV) oxalate, Pu(C2O4)2.6H2O, at 300 °C. Plutonium oxalate is obtained during the reprocessing of nuclear fuel.
[edit] Applications
PuO2 is used in mixed oxide (MOX) fuels for nuclear reactors. Plutonium-238 dioxide is used as fuel for several deep-space spacecraft such as the 'New Horizons' Pluto probe. The isotope decays by emitting α-particles which then generate heat (see Radioisotope thermoelectric generator). There has been some safety concerns, as an accidental orbital earth re-entry may lead to the break-up and/or burn-up of the spacecraft, resulting in the dispersal of the plutonium either, over a large tract of the planetary surface, or within the upper atmosphere.
[edit] Safety
As with all plutonium compounds, it is subject to control under the Nuclear Non-Proliferation Treaty. Due to the radioactive alpha decay of plutonium, all of its compounds, PuO2 included, as well as plutonium metal, are warm to the touch.
[edit] See also
[edit] Sources
- Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
- Space Radioisotope Power Systems Safety
[edit] References
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