Temperature Dependence of the Velocity of Sound in Liquid Metals of Group XIV

The temperature dependences of the velocity of sound in liquid Pb, Sn, Ge, and Si have been measured by means of the pulse transmission technique over temperature ranges of 610–1078 K, 608–1463 K, 1215–1443 K, and 1723–1888 K, respectively. In both liquid Pb and Sn, the velocities of sound decrease linearly with increasing temperature, which is the same temperature dependence as shown in many other liquid metals. On the other hand, the velocities of sound in liquid Ge and Si exhibit anomalous temperature dependences. In Ge, the velocity of sound has a distinct maximum around 1280 K and decreases linearly at higher temperatures. In Si, the velocity of sound increases monotonically with increasing temperature in the temperature range investigated. It is considered that these results predict that the coordination numbers of liquid Ge and Si increase with increasing temperature.