First-Order Liquid-Liquid Phase Transition in Cerium

A. Cadien, Q. Y. Hu, Y. Meng, Y. Q. Cheng, M. W. Chen, J. F. Shu, H. K. Mao, and H. W. Sheng

Phys. Rev. Lett. 110, 125503 – Published 21 March 2013

Abstract

We report the first experimental observation of a liquid-liquid phase transition in the monatomic liquid metal cerium, by means of in situ high-pressure high-temperature x-ray diffraction experiments. At 13 GPa, upon increasing temperature from 1550 to 1900 K high-density liquid transforms to a low-density liquid, with a density difference of 14%. Theoretic models based on ab initio calculations are built to investigate the observed phase behavior of the liquids at various pressures. The results suggest that the transition primarily originates from the delocalization of $f$ electrons and is deemed to be of the first order that terminates at a critical point.

Received 20 November 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.125503

Authors & Affiliations

A. Cadien^1,*, Q. Y. Hu¹, Y. Meng², Y. Q. Cheng³, M. W. Chen⁴, J. F. Shu⁵, H. K. Mao^2,5, and H. W. Sheng^1,6,†

¹School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia 22030, USA
²High Pressure Collaborative Access Team, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA
³Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁴WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
⁵Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA
⁶Center for Computational Materials Science, George Mason University, Fairfax, Virginia 22030, USA