Neutron Scattering Studies of the Dynamics of Imperfect Crystals

Abstract

<p>The effect of random mass disorder on the vibrational properties of simple crystals has been investigated by inelastic neutron scattering. Phonon frequencies and natural widths have been measured in alloy crystals of copper and gold containing 1, 3, and 9 atomic percent gold, in order to study the vibrational properties of the heavy gold atoms in the predominantly copper host lattices. Similar measurements have been made on a crystal of Ni(55%)Pd(45%) in order to investigate the nature of the atomic vibrations in a crystal in which the concentration of the heavy (Pd) atoms is very high. Detailed discussions are given to interpret the results in the light of existing theories.</p> <p>The phonon dispersion curves of several copper-nickel alloys have been measured as part of a research program on the lattice dynamics of transition metals and their alloys.</p> <p>An experiment to measure the phonon dispersion curves of silver has also been carried out.</p>