CXX. Measurement of the elasticity of solid argon with an ultrasonic interferometer

Abstract

The adiabatic compressibility and adiabatic Poisson's ratio for solid argon have been measured by determining the velocities of longitudinal and transverse ultrasonic waves in fine-grained polycrystalline specimens between 65° and 80°k. The cryostat, the ultrasonic interferometer and the preparation of the specimens are described. The compressibility is estimated to rise from 0·42 to 0·62 × 10 ^-10 cm²/dyn between 0°k and the melting-point; Poisson's ratio is 0·30. Existing data are used to estimate the expansivity at various temperatures. The compressibilities are compared with other measurements and with various theoretical estimates. The results are consistent with a Gruneisen parameter γ=αV/κ_sC_p =1·2.