Quantum effects in diffusion: Internal friction due to hydrogen and deuterium dissolved in α-iron

Abstract

This work is an experimental and theoretical study of internal friction due to hydrogen and deuterium dissolved in α-iron. A torsion pendulum is employed which can be used in a Collins cryostat at temperatures in the range 4.2°-300°K. A peak of damping is found in the range 105°-120°K corresponding to that earlier studied by Gensamer and co-workers. An additional peak associated with hydrogen is found at 30°K and, correspondingly, one associated with deuterium is found at 35°K. Magneto-mechanical damping is found at all temperatures, with a peak in the range 4.2°-15°K depending upon treatment of the metal specimen. Theoretical arguments are advanced which suggest that the isotope-shifted peaks are due to atoms dissolved in the undistorted lattice, whose motion must be treated quantum-mechanically to account for the experimental results. Tunneling and localized lattice distortions around the dissolved atom seem to be required by the data and are within the scope of a reasonable theory. © 1961.