REVERSE MONTE-CARLO STUDY OF STRUCTURE CHANGES IN AMORPHOUS PD52NI32P16 UPON ANNEALING

Structure changes in amorphous Pd52Ni32P16 upon relaxation were modeled by means of reverse Monte Carlo (RMC) simulations using neutron-diffraction data from M. Schaal, P. Lamparter, and S. Steeb [Z. Naturforsch. Teil A 43, 1055 (1988)] as input for the RMC program. Two states after annealing (2 h at 570 K and 2 h at 607 K) and the as-quenched state were successfully modeled. The resulting three-dimensional models of the structure were inspected for changes in the nearest-neighbor coordinations (short-range order) and for changes at larger interatomic distances (medium-range order) upon relaxation. It was found that the short-range order is affected by annealing, resulting in, for instance, a sharpening of the Voronoi volume distribution. These results were found to agree with interpretations of experimental atomic mobility studies. The effect of annealing on multibody correlation functions for medium-range distances is much less pronounced than that for the short-range distances, and the two appear to be largely decoupled from one another. These results, together with the observed annealing effect on the decay rate of the peaks of the reduced radial distribution function, suggest that medium-range ordering is not merely a reflection of short-range ordering, but has its origin in a change in propagation of disorder in the structure. Medium-range ordering can therefore be treated as a separate effect of annealing. © 1994 The American Physical Society.