Effects of Solution Concentration on Magnetic NiFe₂O₄ Nanomaterials Prepared via the Rapid Combustion Process.

A rapid combustion process for the preparation of magnetic NiFe₂O₄ nanomaterials was introduced. The experimental results showed that the solution concentration of ferric nitrate was a key factor to control the structure and the properties of magnetic NiFe₂O₄ nanomaterials: the magnetic NiFe₂O₄ nanorods with the diameter of about 15 nm, the length of approximately 100 nm and the saturation magnetization of 18.4-25.3 emu/g could be formed when the solution concentration of ferric nitrate was equal or greater than 1.68 mol/L; the magnetic NiFe₂O₄ nanoparticles with the average particle sizes of 20-32 nm and the saturation magnetization of 10.0-31.8 emu/g could be formed when the solution concentration of ferric nitrate was lower than 1.12 mol/L.