Elastic Moduli and Ultrasonic Attenuation of Polycrystalline Europium from 4.2 to 300°K

The longitudinal and transverse acoustic velocities and the ultrasonic attenuation of high-purity polycrystalline europium metal have been measured by a pulse technique between 4.2 and 300°K. The variations with temperature of the Young modulus $E$, shear modulus $G$, adiabatic compressibility $K_s$, and Debye temperature ${\Theta }_D$, have been determined. The Néel point at 91°K is marked by drastic changes in the elastic moduli and ultrasonic attenuations. Anomalies in the attenuation and in the compressibility are observed at about 150°K. The limiting value of ${\Theta }_D$ is 117°K.