Fast Sound in Expanded Fluid Hg Accompanying the Metal-Nonmetal Transition

Abstract

The dynamic structure factor S(Q,omega) of expanded fluid Hg has been measured up to the metal-nonmetal transition region at 9.0 g cm(-3) (1723 K and 1940 bars) using high-resolution inelastic x-ray scattering, at momentum transfers, Q, from 0.2 to 4.8 A(-1). Analysis in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The effective sound velocity at 9.0 g cm(-3) estimated from the dispersion relation is triple the ultrasonic sound velocity. The present result suggests the existence of fast sound in expanded fluid Hg accompanying the metal-nonmetal transition.

State-of-the-art models for the phase diagram of carbon and diamond nucleation

“…12), the [0001]-graphite sheets transform into [111] diamond planes. rod-like crystal, formed by 4 [111]-faces and 2 bases as [1][2][3][4][5][6][7][8][9][10]-lozenge with the acute angles of θ=70.52 degrees. We then rewrite Eq.…”

“…LLPT's in dense, atomic liquids are typically difficult to probe experimentally: the candidate transitions often occur at extreme pressures and/or temperatures or appear in metastable regions of the phase diagram (and may be hidden by competing solidification). Evidence for LLPT's have been found for a number of atomic systems, such as Cs [6], As [7], Bi [8], Ge [9], Hg [10], S [11], Sb [12], Se [13], Si [14,15], Sn [16], H 2 [17], I 2 [18], N 2 [19,20]. The best established experimental example of a LLPT in an atomic liquid is the case of phosphorus.…”

Experimental techniques of high-resolution inelastic X-ray scattering measurements for supercritical metallic fluids at high temperature and high pressure using synchrotron radiation at SPring-8

“…IXS spectra of the fluid Hg were measured at the thermodynamic states along the saturated vapor pressure curve including the M-NM transition region, as indicated by open squares in figure 5 (a) [18]. The spectra were analyzed using the model function constituting the Lorentzian for the quasielastic component and the damped harmonic oscillator (DHO) for the inelastic excitation.…”

Modifications of structure and properties of liquids at high temperatures

“…Peculiarities were found on the liquid-vapor coexistence curve of Hg [3], as well as electrical conductivity of Hg and Cs [3,4], static susceptibility of Cs [5], Knight shift of Cs and Hg [6,7], sound propagation in Hg [8,9], adiabatic thermal coefficient of pressure of Cs [10] and so on. Despite of the extensive evidence of changes in properties and qualitative understanding of expanding process, there is no quantitive criterion of transition in structure and experimental provements of it.…”