Crystal growth of strontium fluoride from aqueous solution

Abstract

The kinetics of growth of strontium fluoride crystals has been studied in aqueous solution at 25 °C using a constant-composition method in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of strontium nitrate and potassium fluoride solutions. The rate of crystallization is independent of ionic strength and, at low supersaturation, is best represented in terms of a spiral growth mechanism with a reaction order, n= 2, with respect to relative supersaturation. At higher supersaturations, a greater change in rate of growth with increasing concentration (n≈ 4.3) suggests a polynuclear mechanism. Inhibition of crystallization by the presence of phosphonates can be interpreted in terms of a Langmuir isotherm.