New perspectives onto the metal–to–non-metal transition in expanded liquid metals

¹ Department of Chemistry, Physical Chemistry, Philipps-University of Marburg - D-35032 Marburg, Germany
² ISIS Facility, Rutherford Appleton Laboratory - Didcot, OX11 0QX, UK
³ Physics and Geology Department, University of Perugia - Via Pascoli s.n.c., I-06123 Perugia, Italy
⁴ CNR- IOM, Unità di Perugia c/o Physics and Geology Department, University of Perugia Via Pascoli s.n.c., I-06123 Perugia, Italy
⁵ Institute Laue Langevin, ILL - 71 avenue des Martyrs - CS 20156 - F-38042 Grenoble Cedex 9, France
⁶ IOM- CNR, OGG, c/o Institute Laue Langevin, ILL - F-38042 Grenoble, France

Received: 14 February 2018
Accepted: 29 May 2018

Abstract

The collective dynamics of liquid rubidium was measured by inelastic neutron scattering from melting up to 1673 K and 6.4 MPa to explore an electron gas instability, forecasted by theory at sufficient expansion. Pronounced variations are observed when the predicted conditions are approached. They comply with a scenario for the density-driven metal–to–non-metal transition suggested for fluid mercury where the liquid metal decomposes into a nanoemulsion of metallic and non-metallic domains and the metallic domains constantly disappear with ongoing expansion. Collective modes appear as an unambiguous signature of the metallic phase allowing to directly observe this process.