Quasicrystallinity of icosahedral Pd58.8U20.6Si20.6.

Abstract

The uranium differential atomic pair distribution function (DDF) of icosahedral ${\mathrm{Pd}}_{58.8}$${\mathrm{U}}_{20.6}$${\mathrm{Si}}_{20.6}$ is shown to compare well with the vertex-vertex distance distribution function of a quasicrystalline lattice up to 40 A\r{}. The DDF is also compatible, but less favorably, with the icosahedral glass model, which we point out has a local structure very similar to an ideal quasicrystalline structure up to 50 A\r{} or more. Based upon the comparison of theoretical and experimental values of physical density as well, we conclude that the icosahedral ${\mathrm{Pd}}_{58.8}$${\mathrm{U}}_{20.6}$${\mathrm{Si}}_{20.6}$ is better described by the quasicrystalline model.