Impact of grain size and structural changes on magnetic, dielectric, electrical, impedance and modulus spectroscopic characteristics of CoFe ₂ O ₄ nanoparticles synthesized by honey mediated sol-gel combustion method

Abstract

In this work CoFe2O4 spinel ferrite nanoparticles were synthesized by honey mediated sol-gel combustion method and further annealed at higher temperature 500 °C, 700 °C, 900 °C and 1100 °C. The synthesized spinel ferrite nanoparticles is investigated by x-ray diffraction, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), field emission scanning electron microscopy, x-ray photoelectron spectroscopy and vibrating sample magnetometer. The x-ray diffraction study reveals face-centered cubic spinel cobalt ferrite crystal phase formation. The crystallite size and lattice parameter are increased with annealing temperature. Raman and Fourier transform infrared spectra also confirm spinel ferrite crystal structure of synthesized nanoparticles. The existence of cation at octahedral and tetrahedral site in cobalt ferrite nanoparticles is confirmed by x-ray photoelectron spectroscopy. Magnetic measurement shows increased saturation magnetization 74.4 emu g−1 at higher annealing temperature 1100 °C, high coercivity 1347.3 Oe at lower annealing temperature 500 °C, and high remanent magnetization 32.3 emu g−1 at 900 °C annealing temperature. The magnetic properties of synthesized ferrite nanoparticles can be tuned by adjusting sizes through annealing temperature. Furthermore, the dielectric constant and ac conductivity shows variation with frequency (1–107 Hz), grain size and cation redistribution. The modulus spectroscopy study reveals the role of bulk grain and grain boundary towards the resistance and capacitance. The cole-cole plots in modulus formalism also well support the electrical response of nanoparticles originated from both grain and grain boundaries. The dielectric, electrical, magnetic, impedance and modulus spectroscopic characteristics of synthesized CoFe2O4 spinel ferrite nanoparticles demonstrate the applicability of these nanoparticles for magnetic recording, memory devices and for microwave applications.

Raman spectra tell us so much more: Raman features and saturation magnetization for efficient analysis of manganese zinc ferrite nanoparticles

“…The bands are labelled in blue font in Figure a and named according to nomenclature scheme used by Shebanova and Lazor and Thota et al: the A 1g band, the E g band, and three T 2g bands ( g denotes the symmetry with respect to the centre of inversion). It is usual that spinel iron oxides and ferrites have a low scattering efficiency and give rise to wide bands (full width half maximum > 40 cm −1 ) . The spectrum of magnetite, which contains only iron cations and no cation vacancies, features a single contribution for each of the five bands ( R 2 = .995), whereas spinel ferrites with additional order/disorder features contained multiple contributions within the five main bands.…”

“…Despite the abundance of studies and reviews comparing Raman spectra of different spinel‐type iron oxides and ferrites containing various metal dopants, there is no in‐depth knowledge of the relationship of Raman spectra with physical and chemical properties of NPs. Another uncertainty is the origin of Raman bands: certain experimental results suggest that bands in the 600–750 cm −1 spectral region arise from tetrahedral (A‐site) systems and those in the 100–600 cm −1 region from octahedral (B‐site) systems, whereas the other line of experimental and theoretical considerations lead to the conclusion that all active Raman bands arise from A‐sites …”

Fabrication and 3D Patterning of Bio‐Composite Consisting of Carboxymethylated Cellulose Nanofibers and Cobalt Ferrite Nanoparticles

“…CFO has AB 2 O 4 type inverse spinel structure which belong to O h 7 ( Fd‐3 m ) space group with eight formula units per unit cell in which the oxygen ions are distributed among the tetrahedral and octahedral sites occupied by Fe 3+ and Co 2+ metal ions. The observed four Raman bands in CFO sample attributed to E g , T 2g (2), T 2g (3) and A 1g (1) respectively, arise due to the motion of oxygen ions and both A‐site and B‐site ions in the spinel structure . In CMCNF‐CFO composite samples modes at 310 cm −1 and 675 cm −1 are not visible up to 11% CFO concentration.…”

Synthesis, Characterization and Magnetic Hyperthermia of Monodispersed Cobalt Ferrite Nanoparticles for Cancer Therapeutics

“…The lower T 2g and E g frequency modes demonstrate the vibration of the inverse spinel structure of cobalt ferrite. ( Figure 3 ) [ 39 ].…”