Using magnetic field gradients to control the directional solidification of alloys and the growth of single crystals

Abstract

There are various magnetic field based approaches to melt flow control that are used commercially to improve the quality of a crystal grown from the melt. Most of them are based on either a uniform or a rotating magnetic field. In this work, the effect of applying a suitably positioned magnetic field gradient on the growth of single crystals, particularly the interface curvature, growth rate and dopant distribution is investigated. Comparison between crystal growth under the influence of a uniform magnetic field and a magnetic field gradient brings out the significant advantages of the developed method. The use of a magnetic gradient is shown to give a uniform dopant distribution and produce a planar interface. The ease of control as well as the commercial feasibility of such a technique is emphasized. Finally, its promising role in biological macromolecular growth is addressed.