[M-IS14] Interface- and nano-phenomena on crystal growth and dissolution

[MIS14-P07] Numerical Modeling of Oscillatory Zoning Based on the Theory of Growth Hysteresis

*Hiroki Torii¹, Hitoshi Miura¹ (1.Nagoya City University School of Biology and Integrated Sciences )

Keywords:Oscillatory zoning, Crystal growth hysteresis, Numerical calculation, Impurity

Observing the cross-section of the mineral, the part rich in a certain element and the part poor in it accumulate alternately. This is called “oscillatory zoning”. One of the causes of oscillatory zoning is the periodic variation of the crystal growth rate during mineral formation. Previous studies have shown that by considering the interaction between adsorption and desorption of impurities on the crystal surface and crystal growth there, different growth rates can be obtained when the degree of supersaturation is decreased and increased (growth hysteresis [1]). In this study, the time variation of the concentration distribution of surrounding molecules during crystal growth was obtained by solving the unsteady diffusion equation, and the growth rate was calculated from the degree of supersaturation at the crystal surface based on the theory of growth hysteresis. In addition, the amount of impurities incorporated into the crystal was calculated from the percentage of impurities in the solution and the distribution coefficient of the impurities to the crystal. The results showed that the crystal growth rate oscillates periodically with time when the diffusion of impurities in the solution is slower than that of the solute molecules. Correspondingly, the periodic change of the concentration distribution of impurities in the crystal was reproduced (oscillatory zoning). In the future, we plan to investigate the relationship between this model and the actual oscillatory zoning.

Reference: [1] Hitoshi Miura and Katsuo Tsukamoto: Cryst. Growth Des., 13 (2013) 3588-3595.