Face-by-face growth of sucrose crystals from aqueous solutions in the presence of raffinose—II: Growth morphology and segregation

Raffinose segregation into sucrose crystals is experimentally determined along with the modifications of the quantitative sucrose growth morphology, which are in turn related to the different growth conditions. (Craff, σ) morphodromes nicely represent the conflict between the supersaturation and the raffinose concentration in the solution on the growth morphology, while the overall segregation rate is nearly proportional to the linear overall crystal growth rate. Chernov and Burton–Prim–Slichter models, checked to fit our keff and ln(keff-1-1) coefficients as a function of the supersaturation and of the mean linear overall growth rate, do not allow to know whether the segregation occurs either by a process dominated by surface integration, or by additive transfer dominated by volume diffusion within the boundary layer. The distribution of segregated raffinose strictly depends on the {h k l} growth sectors and doped crystals contain deformed lattice zones, as it comes out from X-ray powder diagrams.