Elastic moduli of thulium and ytterbium from 4·2 to 300°K

Abstract

The longitudinal and transverse acoustic velocities of high-purity polycrystalline thulium and ytterbium have been measured by a pulse technique at a frequency of 10 MHz between 4·2 and 300°K. The variation with temperature of the Young moduli E, shear moduli G, adiabatic compressibilities K s , and Debye temperature σ d have been determined. The anomalies in the elastic properties observed in thulium were correlated with the magnetic changes known to occur in this metal at low temperatures. The shape of the compressibility curve suggests that the transition from the antiferromagnetic to the ferromagnetic state in thulium is a gradual process, extending over a temperature interval. No anomalies were observed in the elastic properties of the nonmagnetic ytterbium. The limiting values of the Debye temperatures (at 0°K) of thulium and ytterbium are 200 and 117·5°K, respectively.