Sound Velocity and Absorption of Ultrasonic Waves in the Molten ZnCl₂-PbCl₂ Binary System

Abstract

Sound velocities and absorption coefficients of ultrasonic waves in a molten ZnCl₂-PbCl₂ binary system have been measured with a U.S. spectrometer by the double-transducer method over the frequency range of 5 to 55 MHz. The results obtained are summarized as follows:
(1) Ultrasonic velocities of the molten ZnCl₂-PbCl₂ binary system decrease linearly with increasing temperature except the lower temperature regions of the samples of pure ZnCl₂ and 10.5 mol% PbCl₂. The velocity of pure ZnCl₂ is lowest and that of pure PbCl₂ is highest.
(2) Thermodynamic quantities such as adiabatic and isothermal compressibilities, heat capacity at constant volume and internal pressure were calculated from the measured velocity data, and their composition dependences were determined.
(3) Absorption coefficients and bulk viscosity coefficients and both of their negative temperature dependences are greatest in pure ZnCl₂ and decrease with increasing content of PbCl₂. However, absorption coefficients become constant within the experimental errors in the composition range of more than 50 mol% PbCl₂.
(4) The results obtained in the present work are quite consistent with the previous ones. On the basis of these results, the changes in constituent species with composition of this system are discussed.