Dynamical sound speed and structural inhomogeneity in liquid Te studied by inelastic x-ray scattering

Abstract Inelastic x-ray scattering measurements using high-pressure apparatus were carried out for liquid Te up to 1673 K above the boiling point at the normal pressure. We could obtain the dynamic structure factor S ( Q , E ) of good quality at 1.8 ≤ Q ≤ 22 nm −1 . Although the excitation energies of the acoustic mode are fluctuating more at lower temperatures, we found that the dynamical sound speed at 1.8 and 2.1 nm −1 becomes fast with increasing temperature from 773 to 923 K, similarly to the temperature dependence of ultrasonic sound speed in liquid Te. Despite this unusual temperature dependence at the lowest Q , the sound speed at higher Q is consistent with those obtained by the previous inelastic neutron and x-ray scattering studies, in which the dynamical sound just slows down with increasing temperature. The present results may be correlated with the temperature-driven semiconductor-metal transition in liquid Te, and if so, it is inferred that a domain size of inhomogeneity induced with the transition is comparable to the wave length corresponding to the lowest Q .