Bismuth Whisker Growth

Abstract

Profuse and rapid bismuth‐whisker growth from thin bismuth films occurring only in the presence of manganese is reported. This growth was observed during the heat treatment of thin bismuth‐manganese double layers in the vacuum hot stage on a metallurgical microscope. Optimal conditions for whisker growth are described. The presence of manganese required for whisker growth strongly suggested that the whiskers might be composed of a bismuth‐manganese compound. However, chemical microanalytical tests, melting point determinations, magnetic and magnetoresistivity measurements definitely proved that the whiskers grown were bismuth whiskers. Measurements of magnetoresistance as a function of the orientation of the whiskers in the magnetic field showed that the whiskers were essentially bismuth single crystals with their long axes normal to the principal crystallographic axis The results of exploratory measurements of such additional physical properties of the whiskers as electrical resistivity, temperature coefficient, maximal fracture strength, and strain sensitivity factor are also reported.