Abstract
The crystal size of the ferrites formed hydrothermally from the mixtures of 2α-FeOOH +Zn(OH)2, 2α-FeOOH+NiO or 2α-FeOOH+Co(OH)2, was found to depend on the pH of the medium, and large cubic crystals were observable in alkaline medium, in which complex ions bearing Zn++, Ni++ or Co++ were stable.
In case of the synthesis of these ferrites from coprecipitates, the sizes were very small and nearly independent of the pH.
Copper ferrites were formed only from the coprecipitates or wet mixtures.
Grain growth of the ferrites was scarcely observable during the treatments within 10 hours.
Based on these observations, brief discussions were given on the mechanism of the formation.
