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Title: Anomalous elastic properties across the γ to α volume collapse in cerium

Abstract

The behavior of the f-electrons in the lanthanides and actinides governs important macroscopic properties but their pressure and temperature dependence is not fully explored. Cerium with nominally just one 4f electron offers a case study with its iso-structural volume collapse from the γ-phase to the α-phase ending in a critical point (pC, VC, TC), unique among the elements, whose mechanism remains controversial. Here, we present longitudinal (cL) and transverse sound speeds (cT) versus pressure from higher than room temperature to TC for the first time. While cL experiences a non-linear dip at the volume collapse, cT shows a step-like change. This produces very peculiar macroscopic properties: the minimum in the bulk modulus becomes more pronounced, the step-like increase of the shear modulus diminishes and the Poisson’s ratio becomes negative—meaning that cerium becomes auxetic. At the critical point itself cerium lacks any compressive strength but offers resistance to shear.

Authors:
; ; ; ORCiD logo; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1408129
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Communications; Journal Volume: 8; Journal Issue: 1
Country of Publication:
United States
Language:
ENGLISH
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS

Citation Formats

Lipp, Magnus J., Jenei, Zs., Cynn, H., Kono, Y., Park, C., Kenney-Benson, C., and Evans, W. J.. Anomalous elastic properties across the γ to α volume collapse in cerium. United States: N. p., 2017. Web. doi:10.1038/s41467-017-01411-9.
Lipp, Magnus J., Jenei, Zs., Cynn, H., Kono, Y., Park, C., Kenney-Benson, C., & Evans, W. J.. Anomalous elastic properties across the γ to α volume collapse in cerium. United States. doi:10.1038/s41467-017-01411-9.
Lipp, Magnus J., Jenei, Zs., Cynn, H., Kono, Y., Park, C., Kenney-Benson, C., and Evans, W. J.. Tue . "Anomalous elastic properties across the γ to α volume collapse in cerium". United States. doi:10.1038/s41467-017-01411-9.
@article{osti_1408129,
title = {Anomalous elastic properties across the γ to α volume collapse in cerium},
author = {Lipp, Magnus J. and Jenei, Zs. and Cynn, H. and Kono, Y. and Park, C. and Kenney-Benson, C. and Evans, W. J.},
abstractNote = {The behavior of the f-electrons in the lanthanides and actinides governs important macroscopic properties but their pressure and temperature dependence is not fully explored. Cerium with nominally just one 4f electron offers a case study with its iso-structural volume collapse from the γ-phase to the α-phase ending in a critical point (pC, VC, TC), unique among the elements, whose mechanism remains controversial. Here, we present longitudinal (cL) and transverse sound speeds (cT) versus pressure from higher than room temperature to TC for the first time. While cL experiences a non-linear dip at the volume collapse, cT shows a step-like change. This produces very peculiar macroscopic properties: the minimum in the bulk modulus becomes more pronounced, the step-like increase of the shear modulus diminishes and the Poisson’s ratio becomes negative—meaning that cerium becomes auxetic. At the critical point itself cerium lacks any compressive strength but offers resistance to shear.},
doi = {10.1038/s41467-017-01411-9},
journal = {Nature Communications},
number = 1,
volume = 8,
place = {United States},
year = {Tue Oct 31 00:00:00 EDT 2017},
month = {Tue Oct 31 00:00:00 EDT 2017}
}