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.