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

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 numbers in their respective radial distribution function. The width of the peaks in the radial distribution functions was 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 increased 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.

Short range order in anomalous liquid metals

“…Structure factor obtained from the fitted radial distribution function to the modified quasi-crystalline model for splitted A7 symmetry with and with no displacement of the two first subshells compared with the experimentally measured structure factor. (a) -As [19]; (b) -Sb [49]; (c) -Bi [16,49]. similar to that in the solid phase.…”

“…Using the above relation, we can estimate the variance from sound velocity measurement and find that it is of the same magnitude as that obtained from diffraction measurements, e.g., (σ 1 /a) 2 for Cu is 0.01 from structural measurements and 0.015 from relation (4.1). Recently, such a relation was observed in selected liquid metals including two pnictides [49]. However, we note that it only reproduces this dependence on the sound velocity qualitatively.…”

“…6. Shell contributions to the radial distribution function in the vicinity of the first peak for liquid Sb [49]. The contributions of the two subshells to the first peak can be seen as well as smaller, but not insignificant contributions from the second shell of neighbors to the first peak.…”

“…The radial distribution functions of liquid As, Sb and Bi modeled by the quasicrystalline model using four different symmetries: sc, bcc, fcc and A7. (a) -As (at 1 GPa)[48]; (b) -Sb[49]; (c) -Bi[16,49].…”

Relationship between the short-range order and electrical resistivity in liquid indium-antimony

“…Our calculated results are in excellent agreement with the previous values by first-principles or experimental methods [28,29]. For liquid Sb, the calculated coordination number is 6.8, that is also in excellent consistency with the previously published data [30,31]. In Fig.…”