Role of Zn dopant on superparamagnetic property of CoFe2O4 nanoparticles

Abstract

A series of Co1−xZnxFe2O4 (x = 0, 0.25, 0.5, 0.75 and 1.0) ferrite nanoparticles were synthesized by the chemical precipitation method and annealed at 800 °C for 5 h to remove the strain. Synthesized samples were characterized by means of X-ray diffraction, ultra-violet spectrometer, fluorescence spectrometer, Fourier transform infrared spectrometer, scanning and transmission electron microscope, vibrating sample magnetometer, and electron paramagnetic resonance techniques. The average crystallite size was decreased from 16.2 to 5.6 nm with increasing Zn concentration. UV–Vis absorption spectra indicate that Zn dopant decreased the energy gap of CoFe2O4 magnetic nanoparticles from 3.06 to 3.15 eV. The presence of two main metal oxide bands in FTIR spectra around 456 cm−1 and 553 cm−1 confirmed the octahedral and tetrahedral sites of metal oxide bands. The fluorescence spectra of the synthesized samples show red emission at 681 nm. TEM analysis confirmed the structural transformation from nanorods to nanoparticles as the Zn content increases. The EDAX spectrum confirmed homogeneous mixing of Co, Zn, Fe, and O atoms. VSM analysis shows that increase in Zn concentration decreased the saturation magnetization from 34.2 to 1.6 emu g−1 and the coercivity from 0.111 to 0.015 T. Due to higher coercivity (0.1112 T), synthesized CoFe2O4 nanoparticles may be useful in the production of data storage devices, permanent magnet, parts of electronic circuits, and also in stealth technology.