Low-Temperature Dissipation Peak in Niobium

Abstract

The energy dissipation coefficient $Q^{-1\mathrm{}}$ and the resonant frequency of a circular plate of niobium have been measured as a function of temperature in the range 60-300°K. The measurements have been carried out at four different frequencies from 18 kc ${\sec }^{-1\mathrm{}}$ to 174 kc ${\sec }^{-1\mathrm{}}$ with strain amplitudes smaller than ${10}^{-7\mathrm{}}$. For each vibration mode a pronounced peak is found for the dissipation coefficient while the frequency-temperature curves show a corresponding inflection. The temperature $T_m$ of the dissipation peak depends on the vibration frequency according to an Arrhenius equation which characterizes the thermally activated relaxation effects.