Velocity and attenuation of 29 MHz waves in binary alkali nitrate melts

Abstract

Ultrasonic velocity and attenuation of 29 MHz waves in molten (K,Li)NO₃, (K,Na)NO₃, (K,Rb)NO₃, (Cs,Li)NO₃, (Cs,Na)NO₃, (Cs,K)NO₃, (Cs,Rb)NO₃, and (Rb,Ag)NO₃ are measured as a function of composition and temperature. An improved pulse transmission device is used together with a new measuring cell allowing a temperature accuracy of better than 1 K over the cell-vertical. The temperature dependence of the velocity is linear up to 675 K, the absorption is governed by the activation energy. The velocity and absorption (referred to the square of frequency) values are given in plots and analytical expressions. A reasonable general dependence on composition cannot be given. The isentropic compressibility is listed. The bulk viscosity of the eight investigated systems exceeding the shear viscosity by more than one order of magnitude is given together with an analytical expression for the ratio bulk/shear viscosity based on the Eyring theory.