Phonon Dispersion of Mo-stabilized $\gamma$-U measured using Inelastic X-ray Scattering

TL;DR

This study measures the phonon spectrum of Mo-stabilized gamma-uranium using inelastic X-ray scattering, revealing unusual phonon softening and discrepancies with theoretical predictions, which enhances understanding of its lattice dynamics.

Contribution

It provides the first detailed phonon dispersion measurements of Mo-stabilized gamma-uranium, highlighting anomalies and differences from theoretical models.

Findings

Unusual phonon softening near the H point.

Agreement with theory near the zone center.

Phonon density of states shifted to higher energy.

Abstract

We have measured the room-temperature phonon spectrum of Mo-stabilized $\gamma-$U. The dispersion curves show unusual softening near the H point, q=[1/2,1/2,1/2], which may derive from the metastability of the $\gamma-$U phase or from strong electron-phonon coupling. Near the zone center, the dispersion curves agree well with theory, though significant differences are observed away from the zone center. The experimental phonon density of states is shifted to higher energy compared to theory and high-temperature neutron scattering. The elastic constants of $\gamma$-UMo are similar to those of body-centered cubic elemental metals.