Hydrothermal synthesis of nickel ferrite powders, their properties and sintering

NiFe2O4 powders were synthesized by co-precipitation with ammonia solution using aqueous solution of NiCl2 and FeCl3 followed by hydrothermal treatment of the precipitate. It was found that crystallization in water led to nanometric in size and isometric in shape crystallites, whereas crystallization in sodium hydroxide solution results in particles of well defined walls. Generally, particles crystallized in water were smaller and their particle size distribution was narrower than those crystallized in NaOH solution. Behaviour of the powders under dry compaction and sintering strongly depended on the powder morphology. The powder crystallized in NaOH solution gave compacts of higher density and sintered density of this powder was also higher than that of the powder processed in water.