Synthesis and investigation of structural, morphological, magnetic, dielectric and impedance spectroscopic characteristics of Ni-Zn ferrite nanoparticles

Nanoparticles of Li0.5ZnFe1.5O4 (LiZn2Fe3O8) with the spinel structure were prepared by a sol–gel auto-combustion method at two different annealing temperatures. X-ray diffractograms and Rietveld refinement confirmed the formation of the spinel structure. The morphology was analyzed by electron microscopy, which showed that the grains were composed of different crystallites. Elastic properties were determined from infrared spectroscopy. It was found that the elastic parameters increased with the increase in annealing temperatures. The band gap depends on the annealing temperature and it decreased on increasing the particle size. The conductivity of the specimen annealed at 500 °C followed either the Jonscher's model or Drude's model depending on the temperature range. This conductivity decreased when the annealing temperature was raised by 600 °C. AC conductivity was found to be controlled by the hopping model. A single relaxation phenomenon was evidenced for each sample from impedance analysis. The Nyquist diagram proved that the samples were simultaneously capacitive and resistive and also supported the presence of multiple relaxation times.

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Investigation of the structural, optical, elastic and electrical properties of spinel LiZn2Fe3O8 nanoparticles annealed at two distinct temperatures

Ni0.5Zn0.5Fe2O4 was prepared by the solid state reaction route at different temperatures. The dielectric properties of spinel ferrites were investigated in the frequency range 50 Hz–10 MHz and in the temperature range 300–420 K. Conductance is shown to increase with increasing frequency and temperature. Impedance analyses indicated that the relaxation phenomenon is strongly dependent on temperature and frequency. The impedance plots displayed both intra- and inter-granular contributions. Electrical equivalent circuit was proposed to explain the impedance results. The decrease of giant permittivity values with the increase in frequency proves the dispersion in the low frequency range and is showing the Maxwell–Wagner interfacial polarization.

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Conductivity and giant permittivity study of Zn0.5Ni0.5Fe2O4 spinel ferrite as a function of frequency and temperature

Structural, elastic, optical and dielectric properties of Li0.5Fe2.5 O4 nanopowders with different particle sizes

Structural, morphological, Raman and ac electrical properties of the multiferroic sol-gel made Bi0.8Er0.1Ba0.1Fe0.96Cr0.02Co0.02O3 material

The phase purity, the homogeneity, lattice structure and cell parameters of the Zn 1− x Ni x Fe 2 O 4 was checked by XRD technique. The Ni doping effects on the electrical properties in Zn 1− x Ni x Fe 2 O 4 was investigated using conductance spectroscopy. When introducing nickel in Zn ferrite, the conductivity of the material increases. This effect disappears at high temperature ( T >600 K). The conductivity spectra can be splitted in three regions. In the first one, the conductivity is frequency independent. In the second region, the conductivity can be described by the ω n law. It decreases with increasing frequency in the third region. DC conductivity analysis proves that electronic conduction was dominated by thermally activated Hopping of Small Polaron (SPH) at high temperature and Variable Range Hopping (VRH) at low temperature. For T > T s , where T s is the temperature at which appears a change in the slope of σ dc T (1000/ T ) curves, the activation energy decreases when increasing Ni content (from E a =665 meV for x =0 to E a =283 for x =0.5). For a ll Ni compositions, the activation energy is equal to 280 meV when temperature is lower than T s . From AC-conductivity study, it is found that activation energy decreases with increasing Ni concentration and varies significantly when increasing frequency. Also, the variation of the exponent “ n ” confirms that hopping model is the dominating mechanism in the system.

M. Sajieddine

Papers

Structural and electrical properties of Zn1-xNixFe2O4 ferrite