Lattice Dynamics of YZn

Phonon dispersion curves for YZn along the (0, 0, ζ), (ζ, ζ, 0) (ζ, ζ, ζ) and ({}, {}, ζ) directions have been measured by inelastic neutron scattering at room temperature. A sixth-neighbor force-constant model was used to obtain a fit to the data; there is residual indication of weak forces of still longer range. The frequency distribution function, Debye temperature as a function of temperature, and mean-square atomic displacements were calculated from the model. No Kohn-type anomaly was observed, and YZn was not found to become superconducting down to 1.2 K. Comparison of the dispersion curves of YZn with those of β-brass shows some pronounced differences, though there is a coincidence of accidental degeneracy between the transverse acoustical and transverse optical branches in both materials at (0, 0, {}).