Stability of magnetically suppressed solutal convection in crystal growth from solutions

Convective motions during different crystal growth processes are known to interfere with the quality of the growth process and are hypothesized to be detrimental to the quality of the grown crystal. In crystal growth from solutions for example, without fluid interfaces and free surfaces, gravity driven phenomena such as thermal and solutal buoyancy effects and sedimentation are the primary causes of fluid flows in the system. While crystallization in microgravity can approach diffusion limited growth conditions (no convection), terrestrially strong magnetic fields can be used to control fluid flow and sedimentation effects. In this work, a theory is presented on the stability of solutal convection of a magnetized fluid in the presence of a magnetic field. The requirements for stability are developed and compared to experiments performed within the bore of a superconducting magnet. The theoretical predictions are in good agreement with the experiments and show solutal convection can be stabilized if the surrounding fluid has larger magnetic susceptibility and the magnetic field has a specific structure. Discussion on the application of the technique to protein crystallization is also provided. (C) 2007 Elsevier B.V. All rights reserved.