Crystal growth kinetics in deionised two-component colloidal suspensions

We report first measurements of the crystal growth velocity in deionised two-component aqueous suspensions of charged polystyrene latex spheres. The size ratio was 1:1.3 and mixing ratios up to 18% of the larger particle were investigated. For the pure components limiting growth velocities of (V_∞,120 = 4.8 µm s−1 and V_∞,156 = 2.9 µm s−1) were observed. In the mixture v drops with increasing mixing ratio even below (V_∞,156) of the large minority component. Careful monitoring of the deionisation procedure excludes the explanation of enhanced ionic contamination. Alternatives based on the kinetics of particle attachment and the position of the phase boundary are discussed.