Thermophysical and acoustic properties of heavy rare-earth metals at high temperatures

We have investigated electric resistivity, thermal diffusivity, thermal conductivity, heat capacity, the ultrasonic longitudinal wave propagation velocity, the nonlinear acoustic parameter, and the ultrasonic wave attenuation coefficient in gadolinium, terbium, dysprosium, holmium, erbium, and lutetium. Areas of anomalous changes have been identified on the curves of physical properties plotted against temperature. In a number of cases the origin of these anomalies is clear - magnetic phase transformations -but in some cases the origin is unclear. The effect of impurities upon the position and shape of anomaly areas is ambiguous. The net result is that, irrespective of the origin of phase transformations, anomalous phenomena are observed within a rather broad range of temperatures, which testifies to the fact that phase transformations are not limited to a certain point, but extend over some range. It has been established that the increase of thermal conductivity in rare-earth metals at high temperatures is caused by the increase of its electronic component. (author)