Ultrasonic Velocities in Solid Argon

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: vₗ=1555 m/sec; vₜ₁=1000 m/sec; vₜ₂=835 m/sec. The elastic constants at 0^∘{}K calculated from these values were c₁₁=4.819×10¹⁰ dyn/cm²; c₁₂=1.277×10¹⁰ dyn/cm²; c₄₄=1.235×10¹⁰ dyn/cm².