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Plutonium dioxide
General
Systematic name	Plutonium(IV) oxide
Other names	Plutonium dioxide
Molecular formula	PuO2
Molar mass	276.063 g/mol
Appearance	Yellow-brown crystalline solid.
CAS number	[12059-95-9]
Properties
Density and phase	11.5 g/cm3, solid.
Solubility in water	? g/100 ml (? °C)
Melting point	2400°C (2673.15 K)
Boiling point	2800°C (3073.15 K)
Structure
Molecular shape	Linear
Coordination geometry	?
Crystal structure	Cubic
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	Radioactive, highly toxic.
NFPA 704	1 4 2 OX estimated
DOT Classes
Flash point	Non-flammable.
R/S statement	R: ? S: ?
RTECS number	?
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	?
Other cations	?
Related ?	?
Related compounds	?
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Plutonium(IV) oxide is a high melting point, yellow-brown, crystalline solid at standard temperature and pressure. Due to the radioactivity of plutonium, PuO₂ is warm to the touch, although touching the material may result in serious injury.

Contents 1 Structure 2 Synthesis 3 Applications 4 See also 5 Sources

PuO₂ crystallizes with plutonium ions in a face-centered cubic array. The oxygen atoms create a cubic cell by occupying the tetrahedral holes of the plutonium matrix. The vacancy of the octahedral holes in the crystal lattice allows space for fissile products, affording PuO₂ its utility as a nuclear fuel. During nuclear fission, one atom of plutonium splits into two. The vacancy of the octahedral holes provides room for the new product and allows PuO₂ to retain its structural integrity.

Plutonium metal will spontaneously oxidize to PuO₂ in an oxygenic atmosphere at standard temperature and pressure. However, Plutonium(IV) Dioxide is also recovered during the reprocessing of nuclear fuel by calcination of plutonium(IV) oxalate, Pu(C₂O₄)₂.6H₂O, at 300 °C.

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. As with all plutonium compounds, it is subject to control under the Nuclear Non-Proliferation Treaty.

• IAEA

• Greenwood, N. N.; A. Earnshaw (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. 
• Space Radioisotope Power Systems Safety

• Links to external chemical sources