The reduction and recovery of step velocity in crystal growth induced by convection variation under various gravities

It is demonstrated from the parabolic flight experiments on crystal growth from solution, that a short time disturbance of the crystal growth condition significantly influences the crystal growth kinetics via variation of the mass transport condition by directly observing the movement of spiral steps in situ. An obvious reduction of step velocity was observed in short microgravity periods of less than 20 s, and the step advancing rate recovered quickly under normal gravity. The suppression of impurity adsorption at the growth steps could also be detected in such a short microgravity time by measuring the recovery process of growth steps. It is also shown from the experimental results that the regular change of gravity condition will reduce the time-dependent impurity effect on crystal growth by, probably, variation of the mass transport property.