Ultrasonic Velocities in Solid Argon

Abstract

The pulse technique of echo ranging was used to measure the velocities of ultrasonic waves in cylindrical samples of solid argon for temperatures from 74°K to the triple point (83.80°K). The center portion of these cylinders of solid argon transported the acoustic waves in the manner of a single crystal. The direction of propagation of the ultrasonic waves was deduced to be [110]. Making use of the data of Jones and Sparkes for average continuous transverse waves taken at temperatures from 18 to 62°K, these pulsed ultrasonic-velocity data were extrapolated to the following values at 0°K: $v_l=1555\mathrm{}$ m/sec; $v_{t1\mathrm{}}=1000\mathrm{}$ m/sec; $v_{t2\mathrm{}}=835\mathrm{}$ m/sec. The elastic constants at 0°K calculated from these values were $c_{11}=4.819\mathrm{}\times {10}^{10}$ dyn/${\mathrm{cm}}^2$; $c_{12}=1.277\mathrm{}\times {10}^{10}$ dyn/${\mathrm{cm}}^2$; $c_{44}=1.235\mathrm{}\times {10}^{10}$ dyn/${\mathrm{cm}}^2$.