Abstract
Phonon densities of states (DOSs) of body-centered cubic chromium were measured by time-of-flight inelastic neutron scattering at temperatures up to 1493 K. Density functional theory calculations with both quasiharmonic (QH) and anharmonic (AH) methods were performed at temperatures above the Néel temperature. Features in the phonon DOSs decrease in energy (soften) substantially with temperature. A Born-von Kármán analysis using fits to the experimental DOSs reveals a softening of almost 17% of the high-transverse phonon branch between 330 and 1493 K. The low-transverse branch changes by approximately half this amount. The AH calculations capture the observed behavior of the two transverse phonon branches, but the QH calculations give some inverted trends. Vibrational entropies from phonons and electrons are obtained, and their sum is in excellent agreement with the entropy of chromium obtained by calorimetry, indicating that above 330 K, no explicit temperature-dependent magnetic contributions are necessary.
| Original language | English |
|---|---|
| Article number | 054312 |
| Journal | Physical Review B |
| Volume | 107 |
| Issue number | 5 |
| DOIs | |
| State | Published - Feb 1 2023 |
Funding
We thank Jiao Y. Y. Lin for his discussions and assistance with MCViNE modeling. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This work used resources from National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This work was supported by the DOE Office of Science, BES, under Contract No. DE-FG02-03ER46055.