Study on the synthesis and magnetic properties of rod-shaped NiFe2O4 ferrites via precipitation–toptactic reaction employing Na2C2O4 and NaOH as precipitants

• Rod-shaped NiFe2O4 ferrites are prepared by precipitation–toptactic reaction method.
• Synthesis processes using Na2C2O4 and NaOH precipitants follow different courses.
• The morphology of prepared NiFe2O4 depends on the synthesis process.
• Magnetic behaviors are associated with the morphology of prepared NiFe2O4.

Rod-shaped NiFe2O4 ferrites were prepared by precipitation–toptactic reaction with the aid of pod-like γ-FeOOH template using Na2C2O4 and NaOH as precipitants. The NiFe2O4 ferrite prepared using Na2C2O4 precipitant experienced the formation of γ-Fe2O3 and NiO through dehydroxylation of γ-FeOOH and decomposition of nickel salt, transition of γ-Fe2O3 into α-Fe2O3 and production of NiFe2O4 from the reaction of NiO and α-Fe2O3. The NiFe2O4 ferrite prepared using NaOH precipitant included the formation of γ-Fe2O3 and NiO through dehydroxylation of γ-FeOOH, decomposition of nickel salt and production of NiFe2O4 from the reaction of NiO and γ-Fe2O3. The transition of γ-Fe2O3 into α-Fe2O3 was found in the synthesis process of NiFe2O4 ferrite prepared using Na2C2O4 precipitant. It was found that the NiFe2O4 ferrite prepared using NaOH precipitant had larger length to diameter ratio and better crystallinity, and higher coercivity and lower saturation magnetization.

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