From growth curves, it can be seen that there are variations of growth rate between crystals at a given time and between different sides of the same crystal, which may be a consequence of imperfect mixing within the melt.
This is not altogether unsurprising given that the only mechanism of mixing in this system is likely to be molecular diffusion.
It was also observed that the growth rate of a crystal slows during crystallisation, which is a consequence of the depletion of crystallisable matter as time proceeds.
A theoretical analysis of the growth curves was performed assuming that growth rates are proportional to the supersaturation of a crystallisable pseudo-component from a fixed volume of a well mixed pool of liquid surrounding each crystal.
This predicted a tanh function variation of radius with time, which was able to provide good fits to most data.
The main exceptions were at lower temperatures (e.g. 23 °C), which showed an initially fast period of growth, corresponding to growth of the α polymorph, followed by slower growth of the β’ polymorph.
Apart from that, and the very highest temperature (32 °C), it appeared that growth rates were relatively insensitive to temperature, which was in contrast to nucleation rates which were a strong function of temperature.