Pressure-induced atomic packing change in Pd37Ni37S26 metallic glass

Abstract Pressure-dependent atomic packing structure changes of newly designed sulfur-bearing metallic glass (MG) of Pd37Ni37S26 have been studied by in situ high energy X-ray diffraction and resistivity experiments, and ab initio molecular dynamics simulations from ambient pressure up to 40.9 GPa. Local structural transformation from a low-density amorphous state into high-density one at about 12.8~15.4 GPa has been revealed, which originates from the noticeable kinks during the electron back-donations from S atoms to more localized Ni 3d orbital at about 13~15 GPa and is confirmed by the pressure-dependent resistivity measurements. The origin for the transition is uncovered, i.e., Pd- and Ni-centered clusters first transfer from icosahedral-like structures into higher-coordinated ones, which dominates the initial densification of Pd37Ni37S26 MG during the compression below 13 GPa. In the pressure range above 15 GPa, the low-coordinated S-centered clusters transform into the tri-capped trigonal prism-like structures during the compression of Pd37Ni37S26 MG up to 40.9 GPa. All results obtained here provide insight into the local structural evolution of the sulfur-bearing MGs with pressure.