Template growth mechanism of spherical Ni(OH)₂

Abstract

The microstructures and growth process characteristics of spherical Ni(OH)₂ particles synthesized by the aqueous precipitation-crystallization method were investigated by SEM, TEM and XRD, and their growth mechanism was discussed. With the reaction beginning and continuing, amorphous Ni(OH)₂ nano-crystallites grow up to spherical micron-particles with radially arranged crystallites. The nucleation, crystallization and re-crystallization led by Ostwald ripening simultaneously take place through the whole growth processes. With the course from reversible aggregation to irreversible agglomeration, the Ni(OH)₂ particles tend to grow according to the template growth model: the growth on the crystallite templates stretching in the radius directions is free and quick, while the growth rate for crystallites in other directions is confined due to lower monomers concentration and tends to dissolve. So it is only the radially arranged crystallites that predominate in the particle and lead to characteristic microstructures.

Keywords

spherical Ni(OH)₂ / microstructure / Ostwald ripening / growth mechanism / crystallization