Local structure of liquid gallium under pressure

Abstract

In situ high energy X-ray pair distribution function (PDF) measurements, microtomography and reverse Monte Carlo simulations were used to characterize the local structure of liquid gallium up to 1.9 GPa. This pressure range includes the well-known solid-solid phase transition from Ga-I to Ga-II at low temperature. In term of previous research, the local structure of liquid gallium within this domain was suggested a mixture of two local structures, Ga I and Ga II, based on fitting experimental PDF to known crystal structure, with a controversy. However, our result shows a distinctly different result that the local structure of liquid gallium resembles the atomic arrangement of both gallium phase II and III (the high pressure crystalline phase). A melting mechanism is proposed for Ga, in which the atomic structure of phase Ι breaks up at the onset of melting, providing sufficient free volume for atoms to rearrange, to form the melt.

Gallium Polymorphs: Phase‐Dependent Plasmonics

“…However, gallium has several solid state phases, and these are receiving increasing interest for a number of reasons, chief among them being how its rich polymorphism (see Figure S1 in the Supporting Information) enables a variety of phase‐change systems . These systems are being developed now, even though the local structure of these phases is not well understood, and the local ordering of the liquid phase is still under investigation . In addition, covalent bonding of Ga dimers creates an energy dip at the Fermi level with a strong absorption band around 2.3 eV, and the coexistence of metallic and covalent bonds strongly affects the metallic characteristics of the various Ga phases.…”

Complex Geometric Structure of a Simple Solid-Liquid Interface: GaN(0001)-Ga

“…Both RTILs and gallium are known for their broad liquidus range, and it seems that, by extrapolation of the correlation lengths, the layering at a hard wall could persist up to roughly halfway to their boiling points. The pressures studied here are approximately 2 orders of magnitude lower than those for which pressure effects are expected [30].…”

Structural Ordering in Liquid Gallium under Extreme Conditions

“…The existence of a first-order liquid-liquid phase transition (LLPT) has been postulated [23][24][25][26] on the basis that other candidate polyamorphic liquids exhibit similar anomalous behavior [27], notably water [28], silicon [29], sulphur [30], and phosphorous [9]. Previous in situ structural measurements of liquid gallium at high p are limited to ∼6 GPa [26,[31][32][33][34][35][36][37] by synchrotron x-ray diffraction (SXRD) and 9 GPa by x-ray spectroscopy [38]. At ambient p and T m the average coordination numbern Ga Ga increases from 7 in the solid Ga-I phase to ∼10 [34], compared to a typical value of 11-12 in most liquid metals.…”

“…Recent studies of the local structure of gallium at elevated-p have employed reverse Monte Carlo (RMC) modeling [33,34,36]. RMC is a fitting strategy to generate an atomistic model by minimizing the difference between experimental data (e.g., the pair distribution function) and an input configuration.…”

“…For consistency with a recent RMC study of liquid gallium to 1.9 GPa interpreted by Voronoi tessellation [36], we first consider a selection of Voronoi motifs [ Fig. 4(a)].…”