A Facile Solution Combustion and Calcination Process for the Preparation of Magnetic NiFe₂O₄/SiO₂ Nanocomposites.

A facile solution combustion and calcination process for the preparation of magnetic NiFe2O4/SiO2 nanocomposites was introduced, the as-prepared NiFe2O4/SiO2 nanocomposites were characterized by XRD, VSM, BET, FTIR, SEM, and TEM techniques. The results showed that the single ferrite phase of NiFe2O4 could be formed at 400 °C; the calcination temperature, the content of silica in nanocomposites, and the volume of absolute alcohol were three key factors to the properties of the magnetic NiFe2O4/SiO2 nanocomposites: with the volume of absolute alcohol increasing from 10 mL to 100 mL, the average grain size of NiFe2O4/SiO2 nanocomposites calcined at 400 °C for 2 h with the heating rate of 3 °C/min decreased from about 16.6 nm to 8.4 nm, while the saturation magnetization decreased from about 6.1 Am2/kg to 1.5 Am2/kg; with the calcination temperature increasing from 400 °C to 800 °C, the average grain size of NiFe2O4/SiO2 nanocomposites calcined for 2 h with the heating rate of 3 °C/min and absolute alcohol of 30 mL increased from about 11.0 nm to 14.1 nm, and the saturation magnetization increased from about 3.4 Am2/kg to 24.0 Am2/kg; at the same time, with the content of silica in nanocomposites increasing from 0 to 10 wt.%, the average grain size of NiFe2O4/SiO2 nanocomposites calcined at 400 °C for 2 h with the heating rate of 3 °C/min decreased from about 18.4 nm to 11.0 nm, while the saturation magnetization decreased from about 18.2 Am2/kg to 3.4 Am2/kg.