Domain size correlated magnetic properties and electrical impedance of size dependent nickel ferrite nanoparticles

Abstract

We report here the investigations on the size dependent variation of magnetic properties of nickel ferrite nanoparticles. Nickel ferrite nanoparticles of different sizes (14 to 22 nm) were prepared by the sol-gel route at different annealing temperatures. They are characterized by TGA-DTA, XRD, SEM, TEM and Raman spectroscopy techniques for the confirmation of the temperature of phase formation, thermal stability, crystallinity, morphology and structural status of the nickel ferrite nanoparticles. The magnetization studies revealed that the saturation magnetization (Ms), retentivity (Mr) increase, while coercivity (Hc) and anisotropy (Keff) decrease as the particle size increases. The observed value of Ms is found to be relatively higher for a particle size of 22 nm. In addition, we have estimated the magnetic domain size using magnetic data and correlated to the average particle size. The calculated magnetic domain size is closely matching with the particle size estimated from XRD. Impedance spectroscopy was employed to study the samples in an equivalent circuit to understand their transport phenomena. It shows that nickel ferrite nanoparticles exhibit a non-Debye behavior with increasing particle size due to the influence of increasing disorders, surface effects, grain size and grain boundaries, etc.

Effect of Particle Size on Magnetic Phase Coexistence in Nanocrystalline La0.4Bi0.3Sr0.3MnO3

“…Since ball milling induces more surface defects into the system, increased separation between the core results in the reduced magnetic interaction among the nanoparticle core, thereby resulting in the reduction of net magnetization, and increased coercivity. It is interesting to note that the theoretical value of the shell thickness estimated for LB3SMO-48 sample from the magnetization data (t S = 3.8 nm) is in good agreement Further, from the magnetization plots, the magnetic domain size can be estimated using the relation [60], where T = temperature, ρ = density of LB3SMO (≈10.028 g/ cm 3 ), dM/dH is the value of the slope of M-H curve at H = 0, k B = Boltzmann constant, and M S = saturation magnetization. The values of the domain size thus obtained are given in Table 4.…”

Mineralogical Characterization of Hispano-Moresque Glazes: A µ-Raman and Scanning Electron Microscopy with X-Ray Energy Dispersive Spectrometry (SEM-EDS) Study

“…In the early 16th century, Schneeberg (Germany) was the main source of cobalt for European glass and ceramics, which was exported as zaffre. Zaffre resulted from the calcination of a mineral cobalt ore, such as cobaltite (CoAsS), erythrite (Co 3 (AsO 4 ) 2 )·8H 2 O or skutterudite (Co, Ni, Fe)As 3 , or, according to different references, it was the result of the calcination of the cobalt ore mixed with sand (Gratuze et al, 1996; Zucchiatti et al, 2006; Machado & Vilarigues, 2016). The cobalt compound present in these blue glazes includes Co–Ni–Fe–olivines and Co–Ni–ferrites (spinels) as neoformation compounds.…”

Magnetic Properties of Electrospun Magnetic Nanofiber Mats after Stabilization and Carbonization

“…For comparison with the experimental investigations of the magnetic properties, the micromagnetic simulation software OOMMF (Object-Oriented MicroMagnetic Framework) was used [67], applying finite differences for meshing and solving the Landau-Lifshitz-Gilbert equation of motion [68]. The following material parameters were chosen for Fe 3 O 4 (Fe 2 O 3 /NiO) according to typical literature values [69][70][71][72][73]: M S,magnetite = 500 × 10 3 A/m (M S,nickel-ferrite = 270 × 10 3 A/m), exchange constant A magnetite = 12 × 10 −12 J/m (A nickel-ferrite = 12 × 10 −12 J/m), magneto-crystalline anisotropy constant K 1,magnetite = 11 × 10 3 J/m 3 (K 1,nickel-ferrite = −6.9 × 10 3 J/m 3 ). Since the electrospinning process can be expected to produce arbitrarily oriented crystallographic orientations of the nanoparticles, random orientations of the simulated grains of 5 nm diameter were chosen.…”