Structural, dielectric and magnetic properties of NiFe2O4 prepared via sol–gel auto-combustion method

Abstract

Nickel ferrite (NiFe 2 O 4) powders were synthesized via sol-gel auto-combustion method and the corresponding temperature dependence of microstructure, dielectric and magnetic properties have been investigated. Results of XRD and SEM indicate that the NiFe 2 O 4 samples exhibit a typical single phase spinel structure and a uniform particle distribution. The dielectric constant and dielectric loss measurements show strong frequency dependence of all the samples. The peak observed in frequency dependence of dielectric loss measurements shifts to higher frequency with the increasing sintering temperature, indicating a Debye-like dielectric relaxation. The remanent magnetization increases with the increasing grain size while the coercivity is just the opposite. The saturation magnetization can achieve 50 emu/g when the sintering temperature is more than 1000 o C, and the lowest coercivity (159.49 Oe) was observed in the NFO sample sintered at 1300 o C for 2 h.

Discussion on the Interparticle Interactions in NiFe2O4 and ZnFe2O4 Nanosized Systems Based on the Matrix Effects in the Magnetic Behavior

“…The study of finite size effects is one of the most important research lines in materials science that explores the exotic properties exhibited by the solids as consequence of their reduced particle size. − As the particle size decreases, the surface/volume ratio increases and therefore physical phenomena occurring at the surface must be taken into account when describing the properties of the solid. Superparamagnetism is an interesting consequence of these finite size effects displayed by magnetic nanoparticles in the T B (blocking temperature)-ordering temperature range. − Below a critical size and for a certain temperature range, the formation of magnetic domain-walls is not energetically favorable and therefore the particles are single-domain. ,, Such behavior is characterized by high magnetization values, low saturation magnetic fields, and absence of coercivity as a result of a free rotation of the particle magnetic-moment when the thermal energy overcomes the anisotropy energy barrier. ,, Particles presenting MFe 2 O 4 (M: Ni, Zn) composition with reduced dimensions present promising technological applications to work as ferrofluids, semiconductors, or with biomedical applications . In addition, they result in useful systems to study the particular case of superparamagnetism thanks to their easy preparation and superparamagnetic behavior illustrated in the studied temperature range. , (M 1– x Fe x )­[Fe 2– x M x ]­O 4 materials crystallize with spinel type structure (S. G. Fd 3̅ m ) presenting an inversion degree ( x ) from 0 (normal spinel) to 1 (inverse spinel).…”

Ferrite-Based Nanoparticles Synthesized from Natural Iron Sand as the Fe3+ Ion Source

“…It has been reported by Zhu et al [76] that Bi 25 FeO 40 has good dielectric and electrical properties which can be used as one of integrated circuit components. NiFe 2 O 4 is one of magnetic spinel structures with good magnetic and dielectric properties [77]. In addition, Ni doping in the BiFeO 3 system has an effect on diffraction peak shift to the lower diffraction angle because ionic radius of Ni 3+ ion (0.069 nm) is slightly larger than that of Fe 3+ ion (0.065 nm).…”

Study of magnetic properties of NiZnCu ferrite synthesized by Pechini method and solid-state reactions

“…[10][11][12] Magnetic properties of ferrite synthesized by different types of sol-gel method were investigated and compared to ferrite produced by conventional ceramic methods. [13][14][15][16][17][18][19] It results that ferrites which exhibit approximately the same permeability and coercive field are achieved by both sol-gel and solid-state methods. However, the magnetic performances at high frequency are not presented in these papers so it is difficult to know if this process is well-adapted to the production of low-loss ferrite.…”