Dynamical inhomogeneity of liquid Te near the melting temperature proved by inelastic x-ray scattering measurements

The high frequency dynamics of liquid Te near the melting temperature has been investigated by means of inelastic x-ray scattering measurements. Dynamic structure factors S(Q, E) are obtained at 500, 650 and 800 degrees C. Acoustic excitation is ascertained at each temperature: its Q-dependent phase velocity nu(Q) switches from the high frequency value (IXS)-I-nu to the ultrasonic value nu(s) at a certain momentum transfer (Q = Qtrans). With decreasing temperature, both the 'positiveness' (equivalent to((IXS)-I-nu - nu(s)) / nu(s)) and the effective length (equivalent to 2 pi / Qtrans) increase, which means that the structural relaxation in liquid Te changes greatly in this temperature region. With the aid of a thermodynamic formulation, we show that this should be seen as evidence of dynamical inhomogeneity: it can be greatly enhanced by the metal - nonmetal transition which occurs in the supercooled region. The dynamical inhomogeneity may be induced by a second critical phenomenon, which is similar to the case for liquid water.