Structural, magnetic, dielectric and optical properties of nickel ferrite nanoparticles synthesized by co-precipitation method

Dielectric and magnetic properties of Nickel ferrite ceramics using crystalline powders derived from DL alanine fuel in sol–gel auto-combustion

“…The dielectric constant decreases gradually with frequency in all the three cases ( Fig. 5(a)), the decrease being more rapid in the low frequency region and slow in the high frequency region, and such a behavior has been commonly reported [2,26,32,33]. The decrease in dielectric constant with frequency can be explained by Koop's theory, which considers the dielectric as a MaxwellWagner type inhomogeneous medium consisting of conducting grains separated by highly resistive grain boundaries [26].…”

“…5(a)), the decrease being more rapid in the low frequency region and slow in the high frequency region, and such a behavior has been commonly reported [2,26,32,33]. The decrease in dielectric constant with frequency can be explained by Koop's theory, which considers the dielectric as a MaxwellWagner type inhomogeneous medium consisting of conducting grains separated by highly resistive grain boundaries [26]. The applied field leads to building up of space charge polarization at the grain boundaries, and the grain boundary effects are more dominant over that of the grains and results in the observed dispersion.…”

“…For example, NiFe 2 O 4 ceramics prepared with powders obtained from different fuels (glycine, alanine, poly-mediated and sol gel synthesis) show significant differences in the microstructure and exhibit a strong dispersion in the dielectric properties with frequency [20]. Similarly, powders obtained from different techniques such as (i) soft mechano-chemical synthesis using different precursor powders [21], (ii) molten salt technique [22], (iii) use of different chelating/fuel agents [23], (iv) high-energy ball milling [24], (v) sol-gel method [25], and (vi) co-precipitation methods [26] exhibit varying dielectric characteristics. Likewise the compositionally modified Ni 0.5 Zn 0.5 Fe 2 O 4 powders of varying size obtained by sol gel auto combustion method with different fuels when used for ceramic processing exhibit significant variations in the dielectric characteristics with strong dispersion in the low frequency region (o1 MHz) [4,27,28].…”

Synthesis and characterization of nanocrystalline zinc ferrite spinel powders by homogeneous precipitation method

“…Among them homogeneous precipitation method has great scope for large scale production of nanoparticles. The advantages of this method are better control on particle size and good textural properties of the materials [16,[35][36][37][38]. Moghaddam et al [15] employed the precipitation method for synthesis of ZnFe 2 O 4 nanoparticles using 2.45 GHz microwave irradiation while Lee et al [16] synthesized it at high calcination temperature (650 o C for 6 h).…”

Structural and magnetic characterization of 100-kGy Co60 γ-ray-irradiated ZnFe2O4 NPs by XRD, W–H plot and ESR

“…In the first derivative peak of ESR spectra, several spectroscopic parameters which defines magnetic response in terms of ESR resonance signal are resonance field (H res ), linewidth (DH PP ), g-value and symmetry of resonance peaks [42]. The g-value for the ZnFe 2 O 4 ferrite nanoparticles before and after c-irradiation was calculated from the relation [43] …”