Crystal chemistry, magnetic, and electrical properties of the tetragonal plutonium oxide telluride Pu2O2Te

The preparation and some physical properties of Pu2O2Te are described. The plutonium oxide telluride is isostructural with the corresponding rare-earth oxide tellurides which crystallize in the tetragonal system of La2O2Te-type. Magnetic susceptibility data from 4 K to room temperature are reported together with resistivity measurements. Pu2O2Te is found to be an antiferromagnet below 56 K and a semiconductor with an intrinsic energy gap of 0.65 eV. The magnetic behavior is interpreted in terms of superexchange coupling interactions via nonmetal p orbitals, i.e., in terms of 5f-p overlaps. This conclusion is supported by crystal chemistry considerations by comparison of cell volumes of Pu2O2Te and Nd2O2Te. In Pu2O2Te, the Pu crystal radius is found to be much lower than that of Nd in Nd2O2Te, suggesting some 5f electron ''delocalization'' leading to a crystal radius shrinkage. As for the hexagonal Pu2O2X compounds, with X =O,S,Se, the measured gap may be considered as the energy separation between the chalcogen np band and the 6d-7s conduction band, the occupied 5f states lying just below the np band with some 5f-np overlap