A PHENOMENOLOGICAL STUDY ON CRYSTAL-GROWTH FROM AQUEOUS-SOLUTIONS

Crystal growth from aqueous solutions was phenomenologically studied through solubility, density, thermal conductivity, refractive index, infrared absorption spectra of solutions, partial molar volume, molar polarizability, proton resonance, diffusion coefficient of solute in the solution and equilibrium sedimentation by ultracentrifuge. The concentration and temperature gradient around crystals growing in a two-dimensional cell were measured at the growth interface, and the growth rate of the crystals was found to be proportional to the normal component of those gradients. However, the rate is governed more effectively by the concentration gradient, because the diffusion constant of the solute is about 10(-3) times smaller than the thermal diffusivity. Under an assumption that the growth unit of a crystal from an aqueous solution is crystalline mono molecular, the diffusion constant obtained from the ratio of the growth rate to the concentration gradient is in a good agreement with the diffusion constant of the solute in the solution obtained by ordinarily used methods.