Nano-structure and Phase Transitions in the Liquid Phase of Metallic and Non-metallic Elements

G.C. Vezzoli
Institute for the Basic Sciences, US

Keywords: nanostructure, liquid phase, short range order

Abstract:
The generally accepted version of the structure of the liquid phase is that of a single ''homogeneous'' phase, with a structure which is more or less homogeneous throughout the pressure-Temperature (p-T) field in which it is the stable phase. While data have been accumulating over the past few decades, this model cannot explain well-established facts including second-order type transitions in the liquid state. Herein we present phase diagram data in the liquid state to argue the general case that the liquid of any composition exists in several differently structured nano-phases. In general, one must change our structural model of most liquids especially those with any covalency in bonding, to a mixture of nano-heterogeneous ''regions'' of varying sizes and structures. The local configurational variations that specify what can broadly be called a ''phase'' in the liquid state include local coordination number, bond angle, coordination sphere or polyhedra building blocks, and bond lengths. Liquid states of the elements that are studied herein at atmospheric and high pressure include: mercury, bismuth, tin, sulfur, selenium, tellurium. The understanding of nano-phases in the liquid state can be a precursor to quenching persistently metastable solid phases which may have promise for applications in biotechnology and in materials innovations.

Nanotech 2004 Conference Technical Program Abstract