Abstract
The zeta-phase, existing between 35% and 70% U in Pu, belongs to the high-density phases seen from the point of view of systematics of allotropic modifications of Pu metal. Despite the volume per actinide atom only slightly higher than for alpha-Pu, it magnetic susceptibility is much higher than for alpha-Pu and exceeds even the delta-Pu value.
Similarly, the Sommerfeld coefficient gamma } 40 mJ/mol Pu K(2) exceeds the experimental delta-Pu value. The data confirm that the volume is not the primary control parameter affecting the situation around the Fermi level of common Pu phases and they point against the traditional belief that they are essentially narrow 5f band systems.
Electronic structure calculations suggest that the 5f states of Pu have slightly lower occupancy comparing with delta-Pu. A tendency to the 5f localization can be seen in the Pu dilution situation in the photoelectron spectra. (C) 2011 Elsevier B.V.
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