Plutonium(IV) oxide

Plutonium(IV) oxide
IUPAC name Plutonium(IV) oxide
Systematic name Plutonium(4+) oxide
Other names Plutonium dioxide
Identifiers
CAS number	12059-95-9 Y
ChemSpider	10617028 N
Jmol-3D images	Image 1
SMILES [O--].[O--].[Pu+4]
InChI InChI=1S/2O.Pu/q2*-2;+4 N Key: FLDALJIYKQCYHH-UHFFFAOYSA-N N
Properties
Molecular formula	O2Pu
Molar mass	276.06 g mol−1
Exact mass	275.990 g mol-1
Appearance	Dark yellow crystals
Density	11.5 g cm-3
Melting point	2400 °C, 2673 K, 4352 °F
Boiling point	2800 °C, 3073 K, 5072 °F
Structure
Crystal structure	Fluorite (cubic), cF12
Space group	Fm3m, No. 225
Coordination geometry	Tetrahedral (O2–); cubic (PuIV)
Hazards
Main hazards	RADIOACTIVE
N (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

Plutonium(IV) oxide is the chemical compound with the formula PuO₂. This high melting point solid is a principal compound of plutonium. It can vary in color from yellow to olive green, depending on the particle size, temperature and method of production.^[1]

Structure

PuO₂ crystallizes in the fluorite motif, with the Pu⁴⁺ centers organized in a face-centered cubic array and oxide ions occupying tetrahedral holes.^[2] 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.

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.

Applications

PuO₂ glow through the isotope plutonium-238 in it.

PuO₂ is used in 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 have been concerns that an accidental orbital earth re-entry might lead to the break-up and/or burn-up of a spacecraft, resulting in the dispersal of the plutonium, either over a large tract of the planetary surface or within the upper atmosphere.

Physicist Peter Zimmerman, following up a suggestion by Ted Taylor, demonstrated that a low-yield (1-kiloton) nuclear bomb could be made relatively easily from plutonium oxide.^[3]

Toxicology

See also, Plutonium Toxicity

Plutonium oxide is highly toxic to humans, especially via inhalation.^[4] 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.

See also

• International Atomic Energy Agency

References

1. ^ "Nitric acid processing". Los Alamos Laboratory. http://arq.lanl.gov/source/orgs/nmt/nmtdo/AQarchive/3rdQuarter08/page3.shtml. 
2. ^ Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 1471. ISBN 0-08-022057-6. 
3. ^ Michael Singer, David Weir, and Barbara Newman Canfield (Nov. 26, 1979). "Nuclear Nightmare: America's Worst Fear Come True". New York Magazine. 
4. ^ "Toxicological Profile For Plutonium". U.S. Department of Health and Human Services. 2007-09-27. http://www.atsdr.cdc.gov/toxprofiles/tp143.pdf. Retrieved 2009-04-23. 

External links

• Space Radioisotope Power Systems Safety