An electric field influence on dendritic growth

Abstract

The dendritic growth of ammonium chloride on muscovite mica and glass substrates was studied: firstly under regular conditions and then under electric fields. The dendrites developed under regular conditions disclosed features of the substrate surface structure. In the presence of dc fields, crystalline needles were obtained which grew in the field direction; after the field was removed the needles developed branches from their bulk; shortly afterwards the branches detached themselves from the needles and the regular dendritic growth went on. When the dc fields were perpendicular to the growth chamber, the crystallization was stopped for quite a while: it started after the field removal and went on at a high rate, the dendritic branches detaching from the central stems. Under an ac field the dendritic growth was directed parallel to the field which also thickened the central stems. The effects may be explained by considering changes in the surface free energy induced by the electric field.