Influence of Electric Fields on the Rate of Growth of Molecular Solids

Abstract

THE influence of electric fields on growth processes in insulating and poorly conducting solids has been examined in experiments ranging from those involving biological materials, such as performed by Becker and collaborators on bone growth in experimental animals¹, to Gorskii's work on nucleation in super-cooled organic liquids². A good deal of work has focused on orientation effects occurring on a substrate to which d.c. fields have been applied. For example, Chopra³ has shown effects on orientation of metal films during vacuum deposition, and Sinclair and Calbick⁴ have observed strong variations in orientation of a sodium chloride film deposited on fused silica with an applied d.c. field. We have examined growth rates of insulating crystals in the melt, solution and vapour phases and have experimental evidence that the rate of growth of an organic solid from the vapour phase can be controlled by applying a d.c. electric field to the growing surface. At low growth rates (0.2 µg/min), by applying an electric field of the order of 4,000 V/cm, it is in fact possible to prevent crystal growth.