  We demonstrate a remarkable equivalence in structure measured by total X-ray
scattering methods between very small metallic nanoparticles and bulk metallic
glasses (BMGs), thus connecting two disparate fields, shedding new light on
both. Our results show that for nanoparticle diameters <5 nm the structure of
Ni nanoparticles changes from fcc to the characteristic BMG-like structure,
despite them being formed from a single element, an effect we call
nano-metallic glass (NMG) formation. However, high-resolution TEM images of the
NMG clusters exhibit lattice fringes indicating a locally well-ordered, rather
than glassy, structure. These seemingly contradictory results may be reconciled
by finding a locally ordered structure that is highly isotropic and we show
that local icosahedral packing within 5 atomic shells explains this. Since this
structure is stabilized only in the vicinity of a surface which highlights the
importance of the presence of free volume in BMGs for stabilizing similar local
clusters.
