Experimental measurements of the temperature-dependent Van Hove function in a $\text{Zr}_{80} \text{Pt}_{20}$ liquid

TL;DR

This study measures how the atomic-level dynamics of liquid Zr80Pt20 change with temperature by using neutron scattering and levitation, linking microscopic motion to macroscopic viscosity.

Contribution

It provides the first experimental determination of the Van Hove function in liquid Zr80Pt20 and connects local atomic dynamics to viscosity through decay-time analysis.

Findings

Decay-time of Van Hove peak relates to Maxwell relaxation time

Local cluster coordination changes influence viscosity

Supports predictions from molecular dynamics simulations

Abstract

Even though the viscosity is one of the most fundamental properties of liquids, the connection with the atomic structure of the liquid has proven elusive. By combining inelastic neutron scattering with the electrostatic levitation technique the time-dependent pair-distribution function (i.e. the Van Hove function) has been determined for liquid Zr80Pt20. We show that the decay-time of the first peak of the Van Hove function is directly related to the Maxwell relaxation time of the liquid, which is proportional to the shear viscosity. This result demonstrates that the local dynamics for increasing or decreasing the coordination number of local clusters by one determines the viscosity at high temperature, supporting earlier predictions from molecular dynamics simulations.