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Structural ordering in liquid gallium under extreme conditions

DOI: 10.1103/PhysRevLett.124.145501 DOI Help

Authors: James W. E. Drewitt (University of Bristol) , Francesco Turci (University of Bristol) , Benedict J. Heinen (University of Bristol) , Simon G. Macleod (Atomic Weapons Establishment; The University of Edinburgh) , Fei Qin (University of Bristol) , Annette K. Kleppe (Diamond Light Source) , Oliver T. Lord (University of Bristol)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Physical Review Letters , VOL 124

State: Published (Approved)
Published: April 2020
Diamond Proposal Number(s): 18961

Open Access Open Access

Abstract: The atomic-scale structure, melting curve, and equation of state of liquid gallium has been measured to high pressure ( p ) and high temperature ( T ) up to 26 GPa and 900 K by in situ synchrotron x-ray diffraction. Ab initio molecular dynamics simulations up to 33.4 GPa and 1000 K are in excellent agreement with the experimental measurements, providing detailed insight at the level of pair distribution functions. The results reveal an absence of dimeric bonding in the liquid state and a continuous increase in average coordination number ¯ n Ga Ga from 10.4(2) at 0.1 GPa approaching ∼ 12 by 25 GPa. Topological cluster analysis of the simulation trajectories finds increasing fractions of fivefold symmetric and crystalline motifs at high p − T . Although the liquid progressively resembles a hard-sphere structure towards the melting curve, the deviation from this simple description remains large ( ≥ 40 % ) across all p − T space, with specific motifs of different geometries strongly correlating with low local two-body excess entropy at high p − T .

Journal Keywords: Atomic & molecular structure; Equations of state; Liquid-liquid phase transition; Disordered systems; Liquid metals; Ab initio calculations; Molecular dynamics; Pressure techniques; X-ray diffraction

Subject Areas: Physics


Instruments: I15-Extreme Conditions

Documents:
PhysRevLett.124.145501.pdf