Electronic Structure and Stability of the Pd-Ni-P Bulk Metallic Glass

Abstract

In order to investigate the stabilization mechanism of the Pd-Ni-P bulk metallic glass (BMG), electronic structure of the (Ni,Pd)₉P trigonal clusters with a phosphorus atom in the center and that of the relevant crystals were investigated by use of first principle calculations; discrete variational Xα potential (DVXα) cluster calculation and full potential linearized augmented planewave (FLAPW) band calculation. Presence of the covalent bonds between phosphorus and nickel/palladium was confirmed in the relevant crystals by observing their density of states, that is characterized by the narrow bandwidth and the eigen values well reproduced by the (Ni,Pd)₉P cluster calculation. We found, as a consequence of the theoretical calculations, that the electronic structure and the number of electrons in the trigonal cluster allow the (Ni,Pd) atoms at the vertices and sides of the clusters to be shared by the neighboring ones, and that the connection-direction and connection-angle of the cluster do not significantly alter the cluster levels nor the internal energy of the cluster. Consequently the network of the cluster has large degree of flexibility with keeping the low internal energy. These characteristics lead to the highly-stable Pd-Ni-P BMG.