Untersuchung zur Segregation von Ammoniumfluorid bei Eis-Einkristallen

The composition of ice single crystals grown from dilute aqueous solutions of ammonium fluoride (concentrationsc ₀=4×10^?4...5×10^?2 mole/I) was investigated. The crystals were divided into parts, which were melted separately. Then the electrical conductivities and thepH-values of the melts were measured. A comparison of the measured values with those of the aqueous solutions of ammonium fluoride shows that the components of ammonium fluoride were not built into the ice in ratios corresponding to the stoichiometric composition of the NH₄F molecule. Therefore, it is impossible to describe the segregation with only one segregation coefficient. The acid components are predominating in the crystals. The deviation from the stoichiometric composition is largest in the initial parts of the crystals.