Homogene Keimbildung und Keimwachstum von γ-MnO2

Abstract

Fast oxidation of Mn²⁺ in an acid solution by S₂O₈^2- leads to spheres of agglomerated, very small crystallites of γ-MnO₂. When the supersaturation in manganese begins to drop, needles grow out of the initial spheres and the familiar hedgehog-like particles form. Crystallite growth can be further enhanced by heating the γ-MnO₂ in suspension with 2N HNO₃ under reflux. Extended recrystallization, however, leads to nucleation of β-MnO₂ and the sample eventually transforms entirely into this phase.