Suppression of convection using gradient magnetic fields during crystal growth of NiSO4·6H2O
P. W. G. Poodt, M. C. R. Heijna,K. Tsukamoto, W. J. de Grip, P. C. M. Christianen, J. C. Maan,W. J. P. van Enckevort and E. Vlieg

Abstract
A magnetic field was successfully used to suppress buoyancy driven convection during solution growth of a NiSO4·6H2O crystal. The disappearance of the convection plume and the expansion of the depletion zones, typical for crystal growth in the absence of gravity, were observed with schlieren microscopy when the product of magnetic field and field gradient corresponds to the condition that for all relevant concentrations buoyancy is compensated by paramagnetic counterforces. We show both theoretically and experimentally, that levitation of the growth solution is not the correct condition to suppress convection.