Structural, optical, dielectric, and magnetic properties of spinel MFe2O4 (M = Co and Zn) nanoparticles synthesized by CTAB-assisted hydrothermal method

Abstract

Nanostructured MFe2O4 (M = Co and Zn) ferrites have been successfully synthesized by hydrothermal method using cetyltrimethylammonium bromide (CTAB) as a surfactant and ammonium hydroxide (NH4OH) as a precipitating agent at a moderate temperature (∼160 °C) for 10 h and subsequent calcination of the precursors at 400 and 600 °C. These ferrite materials have been characterized by X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), thermogravimetric analysis−differential scanning calorimetry (TGA−DSC), Fourier transformed infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The CoFe2O4 is found to have both hexagonal and spherical surface morphologies and for ZnFe2O4 a spherical morphology is obtained at 600 °C. Optical, dielectric, and magnetic properties of these ferrites have been investigated. CoFe2O4 exhibits ferromagnetism at room temperature. In contrast, ZnFe2O4 shows paramagnetism at room temperature. The Ms and Hc values are observed to increase, respectively, from 74.2 emu g−1 to 78.9 emu g−1 and 1221 Oe to 1411 Oe for CoFe2O4 as the calcination temperature increases from 400 °C to 600 °C. This is related to better crystallinity because of calcination at higher temperature. Dielectric properties of the ferrite materials are also enhanced with the increase in the calcination temperature.