Critical Sound Attenuation in the System Ga–Bi

Sound attenuation measurements were performed on a liquid Ga–Bi mixture at the frequencies 16.6, 25.5, 37.6, and 49.7 MHz, over a composition range 0.20–0.75 weight fraction Bi and in the temperature range 0.3–9.9°C above the critical temperature of the mixture. The velocity of sound was measured at 25.5 MHz and at each of the above temperatures and compositions. No critical effects were evident in the velocity of sound measurements. Using the results of the velocity and attenuation measurements, the critical temperature and composition of the Ga–Bi system were determined as 263.1°C and 0.60 weight fraction Bi, respectively. The Fixman theory was tested against the attenuation results. The temperature dependence of the Fixman theory could be made to conform to the attenuation results if a value for the Debye short‐range correlation length $l$ of 4.5 Å was used. The frequency dependence of the attenuation data was found to be in only rough agreement with the Fixman theory over the temperature interval of the measurements. The composition dependence of the attenuation measurements was compared with the predictions of the Flory–Huggins solution model when combined with the Fixman theory. The experimental attenuation results were found to exhibit broader attenuation maxima with composition than those predicted by the above theory.