Plutonium oxysulfides


Plutonium oxysulfides are compounds of plutonium, oxygen and sulfur, where sulfur exists as sulfide or polysulfide ions and plutonium exists in the trivalent state or tetravalent state. They are mixed oxide-sulfides and include Pu2O2S, Pu4O4S3, PuOS, and Pu2O2S3.

Compounds

Pu2O2S

Diplutonium dioxide monosulfide is formed by reacting plutonium oxide and plutonium sesquisulfide at 1400 °C:
Or the decomposition of Pu4O4S3 at 1100 °C.
It is isostructural with cerium oxysulfide, having a hexagonal structure with lattice parameters a=3.929 and c=6.768 Å.

Pu4O4S3

Tetraplutonium tetroxide trisulfide is formed by the decomposition of PuOS at 600 °C. It is a mixed valence compound, containing a 1:1 ratio of plutonium in its +3 and +4 oxidation states. It has a complex pseudo-hexagonal structure, with lattice parameters a=4.06, b=6.72, c=3.87 Å, and β=118°.

PuOS

Plutonium monoxide monosulfide is formed by reacting sulfur with Pu2O2S at 500 °C, or by reacting plutonium monosulfide with oxygen:
It is unstable, dissociating to Pu4O4S3 at 600 °C. It adopts the same structure as uranium oxysulfide, UOS, with which it forms a solid solution. Its structure is tetragonal, with lattice parameters a=3.80 and c=6.59 Å. It contains plutonium in its +4 oxidation state.

Pu2O2S3

Diplutonium dioxide trisulfide is the other product formed by reacting Pu2O2S with sulfur. It is a polysulfide with plutonium in its +4 oxidation state, and its formula can be written as. It has a tetragonal structure with lattice parameters a=3.95 and c=7.95 Å.