Structure and properties of an amorphous palladium-silicon alloy

Abstract

A study has been made of the structure and electrical properties of an amorphous phase containing 80 at. % Pd and 20 at. % Si, obtained by rapid quenching from the liquid state. The radial distribution function, which was computed for this phase from the x-ray diffraction pattern, indicates an atomic arrangement with 11.6 nearest neighbors at an average distance of 2.79 A. This is very similar to that of pure Pd which has twelve nearest neighbors at 2.77 A. The diffuse diffraction pattern found by electron diffraction and the absence of detectible structure in transmission electron microscopy help to confirm the amorphous structure of the alloy. The electrical resistivity of the amorphous alloy is characterized by a very small temperature coefficient (about 9 x 10[superscript -5]/°K between 4°K and 625°K). The resistivity of the liquid alloy was also measured between 1073° K and 1400°K. A correlation was established between the resistivity of the amorphous and liquid phases. These findings are discussed on the basis of the nearly free electron theory of liquid conductors. The crystallization of the amorphous alloy was observed by transmission electron microscopy and the rate of crystallization was measured in a temperature range from 280° to 350°C.