REDUCED SHORT-RANGE ORDER IN AMORPHOUS-SILICON GOLD-ALLOYS

Two types of amorphous solids are generally distinguished: metallic and covalent ones, corresponding with respect to their atomic structure to metallic and covalent liquids. The results presented in this paper suggest that there is a novel type of amorphous solid, corresponding to a third class of liquids, the so called non-simple liquids formed by certain group IV and V elements and some of their alloys. An X-ray diffraction study of the atomic structure of amorphous Si1-xAx (0.14 less-than-or-equal-to x less-than-or-equal-to 0.34) prepared by in situ consolidation of inert gas condensed amorphous nanometer-particles suggests narrow distributions of nearest neighbour interatomic spacings for Si-Au and Au-Au and an exceptionally broad distribution for Si-Si. The short-range order of the alloys is significantly reduced as compared with metallic or covalent amorphous solids.