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

Abstract

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\ifmmode^\circ\else\textdegree\fi{}K. The variations with temperature of the Young modulus $E$, shear modulus $G$, adiabatic compressibility ${K}_{s}$, and Debye temperature ${\ensuremath{\Theta}}_{D}$, have been determined. The N\'eel point at 91\ifmmode^\circ\else\textdegree\fi{}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\ifmmode^\circ\else\textdegree\fi{}K. The limiting value of ${\ensuremath{\Theta}}_{D}$ is 117\ifmmode^\circ\else\textdegree\fi{}K.