Electronic structure of Pd-based bulk metallic glasses

Abstract

From high-resolution X-ray photoelectron spectroscopy (XPS) of Pd x Ni (80− x) P 20 bulk metallic glasses (BMGs) we observe bonding states in the ternary glasses that cannot be simulated by linear combinations of the valence bands of the binaries. Thus, the bonding in the ternary glasses is qualitatively different from those of the binary alloys of this composition range. Further, we observe that there are more such states in Pd 40Ni 40P 20 than in Pd 40.5Cu 40.5P 19, explaining the greater glass-formability of the former. Within the bulk glass formation range, 30⩽ x⩽60, the valence band of the most stable glass, Pd 40Ni 40P 20, is found to be a linear combination of those of the glasses at the extremes of this range. Comparison of XPS core level binding energies of glasses and crystals in Pd x Ni (80− x )P 20 show that the electronic structure of glasses is closest to that of the corresponding crystals at x=30, which agrees with a minimum in the heat of crystallization for this composition.