The Crystal Dynamics of Platinum

Abstract

<p> The dispersion relations in Platinum have been measured at 90°K by the inelastic scattering of thermal neutrons. Born-von Karman models of the force system have been calculated by a process of linear least squares fitting to the dispersion curves. Fourth neighbour forces with weaker interactions extending to at least sixth neighbours are required to fit the data. A frequency distribution has been computed using the force constants of the most realistic model.</p> <p> Some interesting anomalous behaviour in the [035]T1 branches of both Platinum and Palladium has been investigated in detail at temperatures of 90,296 and 473°K. A qualitative analysis indicates that the behaviour is caused by the Kohn effect though its manifestation is rather unusual.</p>