Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, part II: Iron (III) and nickel (II)

Crystallization of nickel fluoride hydrate from mixed pickle acid and the influence of Ni(II) on growth rate of β-FeF3·3H2O have been studied. Iron and nickel crystallize into an unidentified Fe/Ni fluoride hydrate crystal having the overall mol ratio of Ni, Fe, and F equal to 1:2:8, which is in accordance with the number of fluoride ions needed to balance the positive charges of Ni and Fe. The most probable empirical formula of this material is (FeF3)2NiF2(H2O)6–10. By seeded isothermal desupersaturation experiments, growth rate of β-FeF3·3H2O crystals at 50 °C has been studied in a hydrofluoric acid and nitric acid solution containing Ni(II). It is found that the growth rate of β-FeF3·3H2O is essentially uninfluenced by the presence of 4 g/kg Ni(II).