Abstract
Understanding the dynamics of liquids at the atomic level remains a major challenge. Even though viscosity is one of the most fundamental properties of liquids, its atomistic origin is not fully elucidated. Through inelastic neutron scattering experiment on levitated metallic liquid droplets, the time-dependent pair correlation function, the Van Hove function, was determined for Zr50Cu50 and Zr80Pt20 liquids at various temperatures. The time for change in local atomic connectivity, τLC, which is the timescale of atomic bond cutting and forming, is estimated based on the exponential decay of the nearest neighbor peak of the Van Hove function. At high temperatures above the crossover temperature TA, τLC is equal to the Maxwell relaxation time, τM=η/G∞, where η is the macroscopic shear viscosity and G∞ is the high-frequency shear modulus. Below TA the ratio of τM/τLC increases with decreasing temperature, indicating increased atomic cooperativity as predicted by molecular dynamics simulation.
| Original language | English |
|---|---|
| Article number | 024309 |
| Journal | Physical Review B |
| Volume | 110 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jul 1 2024 |
Funding
The authors thank A. J. Vogt, D. G. Quirinale, and C. E. Pueblo for their help in the neutron scattering experiments. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The work at Washington University in St. Louis was partially supported by the National Science Foundation under Grants No. DMR-15-06553 and No. DMR-19-04281 and by the National Aeronautics Space Administration (NASA) under Grant No. NNX16AB52G. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory.