GROWTH ANISOTROPY OF N-METHYLUREA CRYSTALS IN METHANOL

The present work investigates the relationship between the growth kine tics and the crystal structure of N-methylurea (NMU) crystals. Anisotr opy of the step kinetic coefficient, step free energy, and normal grow th rate of NMU crystals may be explained on the basis of a model which links the above quantities with the energy of kink formation in the g rowth steps. The proportionality condition between the solid-solid and solid-liquid bonds has been applied, and the coefficient of this inte raction was obtained experimentally. The anisotropy of the crystal hab it observed in these experiments is much greater than that predicted b y the attachment energy model. We suggest that the method may be gener ally used to quantify the crystal growth anisotropy of molecular cryst als.