Electronic properties of amorphous nickel phosphorus alloys

Abstract

Resistivity data on a variety of other metallic glasses are re: viewed and also found to be compatible with the model provided here for amorphous NiP. It is therefore concluded in this thesis that liquid transition metal theory provides the basic framework for describing electron transport in metallic glasses.

[abstract condensed]

The resistivities of five amorphous NiP samples were measured between 4.2 and 293K and show an increase from 100 to 180 µ Ω cm as the phosphorus content increases from 15 to 25.4 at.%. Corresponding to this increase is a change in the temperature coefficient of resistivity (TCR) from positive to negative values with the transition occurring at about 23 at.% P. Information required for interpreting these data were obtained from heat capacity measurements on amorphous NiP samples conducted from 0.15 to 15K and from X-ray diffraction measurements.

It is shown that liquid metal theory provides the basis for explaining electron transport in metallic glasses. Electrodeposited glassy nickel phosphorus is a convenient system for demonstrating this because it is a binary alloy which is amorphous over a wide composition range (15 to 25 at.%). An additional advantage is that, because of the five phosphorus valence electrons, small composition changes are expected to cause large changes in the Fermi sphere diameter; this is the basic parameter for determining the resistivity according to liquid metal theory.