On the relation between the microscopic structure and the sound velocity anomaly in elemental melts of groups IV, V, VI

TL;DR

This study investigates the microscopic structure of liquid elements in groups IV, V, and VI and its relation to sound velocity anomalies, revealing a correlation between structural rigidity and velocity changes.

Contribution

It provides the first detailed neutron diffraction analysis linking microscopic structural features to sound velocity anomalies in these elemental melts.

Findings

Peak widths in radial distribution functions do not increase with temperature.

A correlation between structural rigidity and sound velocity anomalies is established.

The phenomenological model agrees with existing data for these liquids.

Abstract

The sound velocity of some liquid elements of groups IV, V and VI, as reported in the literature, displays anomalous features that set them apart from other liquid metals. In an effort to determine a possible common origin of these anomalies, extensive neutron diffraction measurements of liquid Bi and Sb were carried out over a wide temperature range. The structure factors of liquid Sb and Bi were determined as a function of temperature. The structure of the two molten metals was carefully analyzed with respect to peak locations, widths and coordination number in their respective radial distribution function. The width of the peaks in the radial distribution function were not found to increase and even decreased within a certain temperature range. This anomalous temperature dependence of the peak widths correlates with the anomalous temperature dependence of the sound velocity. This correlation may be accounted for by increasing rigidity of the liquid structure with temperature. A phenomenological correlation between the peak width and the sound velocity is suggested for metallic melts and is found to agree with available data for normal and anomalous elemental liquids in groups IV-VI.