Infracrystallization in the monodisperse sperical silica particles suspensions (MSSP) unstable in the process of sedimentation
V.V. Serdobintseva, D.V. Kalinin
The infracrystalls (IC) from the structural units (SU-charged MSSP, 250±5 nm in diameter with diffusion counterion atmosphere from NH4+) are formed in the concentrated layer of alcohol suspension at the bottom of vessels, when the forces of electrostatic repulsion of couterion atmospheres and the amount of gravitational forces along with the forces of molecular gravitation reach equilibrium. It makes possible to use the Alder-Hoover model in the analysis of phase transition and the transition occurs at concentration of S~49 vol. % (Ck). The temperature dependence of the rate of the IC linear growth (R) demonstrates its activation character. At low electrolyte concentration in disperse medium it is defined by SU diffusion at the interface according to the Frenkel kinetic theory of liquids.
At concentration of SU=Ck the volumetric crystallization of the suspension, which has reached pretransitional state, takes place. The IC output (A) is determined by the Kolmogorov equation A=1–exp[–(kT)m], where km=παR3/3, α – the probability of formation of crystallization center per a unit of volume (V) in a time unit (t). The total of growing IC (N) is determined as N~0,9V·(α/R)4/3, and it agrees satisfactorily with the experiment.
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