A COMPARISON OF CRYSTAL-GROWTH KINETICS BY USE OF CHEMICAL-POTENTIAL DIFFERENCE AND CONCENTRATION DIFFERENCE

A Spherical Void Electrodynamic Levitator Trap (SVELT) was used to mea sure the water activity in the supersaturated aqueous solutions of six materials, NaCl, (NH4)(2)SO4, KH2PO4, NH4H2PO4, KAl(SO4)(2) . 12H(2)O and glycine. The relationship between chemical potential and concentr ation was obtained using a fifth order polynomial fit. A comparison of the order of the crystal growth rate obtained from the use of chemica l potential difference and concentration difference was made. The orde r of crystal growth rate calculated from concentration difference was found to be close to that obtained from chemical potential difference at low supersaturation, while at higher supersaturation a deviation wa s noted.