INTERATOMIC VOLUME IN ATOMIC MODELS OF AS-QUENCHED AND RELAXED AMORPHOUS PD52N32P16

It is generally recognised that excess interatomic volume plays an important role in the atomic mobility in non-crystalline matter. In this paper the interatomic space is analyzed in terms of entities named voids, using atomic models of amorphous Pd52Ni32P16 in the as-quenched state and in a relaxed state, obtained by reverse Monte Carlo simulation. It is found that structural relaxation involves a well-defined process: the breaking up of larger voids, with ten or more surrounding atoms, into smaller ones. The smaller voids appear to be an intrinsic characteristic of the non-crystalline structure; their volume distribution does not depend on the state of order. By contrast, the volume distribution of larger voids changes markedly on relaxation, indicating that they are related to atomic mobility. Interpretations for the experimentally observed changes in diffusivity upon relaxation are also discussed.