Synthesis, characterization and properties of nickel based zinc ferrite nanoparticles (original) (raw)
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Journal of Applied Physics, 2004
Nickel zinc ferrite nanoparticles (Ni 0.20 Zn 0.44 Fe 2.36 O 4 ) have been produced at room temperature, without calcination, using a reverse micelle process. Particle size is approximately 7 nm as determined by x-ray powder diffraction and transmission electron microscopy. Saturation magnetization values are lower than anticipated, but are explained by elemental analysis, particle size, and cation occupancy within the spinel lattice. Extended x-ray absorption fine structure analysis suggests that a significant amount of Zn 2ϩ , which normally occupies tetrahedral sites, actually resides in octahedral coordination in a zinc-enriched outer layer of the particles. This ''excess'' of diamagnetic Zn can thus contribute to the overall decrease in magnetism. Further, this model can also be used to suggest a formation mechanism in which Zn 2ϩ is incorporated at a later stage in the particle growth process.
Structural And Magnetic Properties Of Ni-Zn Ferrite Nanoparticles
2010
Nickel zinc ferrite nanoparticles of the composition NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) have been synthesized by the chemical co-precipitation method. The samples were characterized by X-ray diffraction, TEM, EPR, DC magnetization and AC susceptibility measurements. The X-ray diffraction patterns confirm the synthesis of single crystalline phase of NixZn1-xFe2O4 (x = 0.1, 0.3, 0.5) nanoparticles. Lattice parameter decreases with the increase in nickel content. The magnetic measurements shows superparamagnetic nature of the samples for x = 0.1 and 0.3 whereas for x = 0.5 the material shows ferromagnetic nature. The saturation magnetization is low and increases with increase in nickel content. The superparamagnetic nature of the samples is supported by the EPR and ac susceptibility measurement studies. The blocking temperature increases with the nickel concentration. The changes in the magnetic properties have been explained by the redistribution of the cations on A and B sites.
Nickel ferrite nanoparticles were synthesized by wet chemical co-precipitation method and the corresponding temperature dependent structural, magnetic and optical properties of these nanoparticles have been investigated. X-ray diffraction patterns show the single phase cubic spinal crystal structure belonging to the space group Fd3m. The average crystallite size varies in the range 8–20 nm with varying sintering temperature. Raman spectroscopy exhibits a doublet-like peak behaviour which indicates the presence of mixed spinel structure. The saturation magnetization, coercivity and remanence increase with increasing sintering temperature from 250 to 550 C. The non-saturation and low values of magnetization at high fields indicate the strong surface effects to magnetization in NiFe2O4 nanoparticles. The g-value calculated from electron spin resonance spectrum indicates the transfer of divalent metallic ion from octahedral to tetrahedral site (i.e. mixed spinel structure). The dielectric permittivity, loss tangent and ac conductivity measurements show strong temperature dependence at all frequencies. The observed ac conductivity response suggests that the conduction in ferrite nanoparticles is due to feeble polaron hopping between Fe3+/Fe2+ ions. Room temperature UV–vis diffuse spectra indicate that NiFe2O4 is an indirect band gap material with band gap ranges from 1.27 to 1.47 eV with varying sintering temperature. The photoluminescence study clearly indicates that the Ni2+ ions occupy both octahedral and tetrahedral sites confirming mixed spinel structure.
Synthesis and magnetic studies of Ni-Zn ferrite nanoparticles
… of Optoelectronics and …, 2006
Ni-Zn ferrite nanoparticles of the system, Ni 0.65 Zn 0.35 Fe 2 O 4 , were synthesized by a soft chemical approach of coprecipitation method. These nanoparticles were separated into four batches and they were annealed at different temperatures from 200 to 800 o C for improved crystallization. All the samples were then characterized by X-ray diffraction, vibrating sample magnetometer and ferromagnetic resonance spectrometer techniques. The XRD patterns confirm spinel structures while the particle sizes, ranging from 9.9 to 15.7 nm, increase with the increase in heat treating temperature. The magnetization values are extremely small even at 10 kOe fields with vanished hysteresis at lower heat treating temperatures; thus leading close to the superparamagnetic nature. The resonance parameters deduced from the FMR spectra are in support of the magnetisation data.
Effect of Cation Distribution on Structural and Magnetic Properties of Nickel Cobalt Zinc Ferrites
Advances in Materials Science and Engineering, 2013
Nanoparticles of Ni (0.8−x) Co (0.2) Zn (x) Fe 2 O 4 (= 0.2, 0.4, and 0.6) are prepared by chemical coprecipitation method. Effects of zinc substitution on structural and magnetic properties have been investigated. The X-ray diffraction and infrared spectroscopy are used to characterize the samples. The XRD pattern of the samples provides evidence of single phase formation of spinel structure with cubic symmetry. It is observed that the particle size decreases and lattice parameter increases with the increase in zinc concentration. TEM micrographs show a well-defined nanocrystalline state with an average particle size of around ≈17 nm. The B-H loops of all samples that are obtained by using vibrating sample magnetometer are displayed. The effect of Zn addition on saturation magnetization and the coercivity of all the samples are discussed.
Ni 0.6−x Mn x Zn 0.4 Fe 2 O 4 (x = 0.0–0.6) samples were synthesized using a combustion technique involving a mixture of hexamine and metal nitrate. XRD measurements confirmed the single-phase formation. The lattice parameters were found to increase gradually with increasing Mn substitution. The peak broadening observed for these ferrites indicates their nanocrystalline nature. FTIR spectra display two absorption bands which are characteristics of M–O stretching in tetrahedral and octahedral sites in the spinel lattice. SEM observations show that the particles occur as loose agglomerates. Lower DC resistiv-ity values in the range of 10 6 to 10 7 cm observed at room temperature suggests the protonic conductivity due to moisture trapped inside the pores. The resistivity was found to decrease with increasing Mn substitution at higher temperatures. AC susceptibility studies reveal the presence of clusters of both superparamagnetic and single-domain particles. Curie temperatures were found to decrease with increasing Mn concentration. The low dielectric losses of about 10 −2 in the higher frequency region were observed.
Structural and Electrical Properties of Nano [Ni 0.6 Zn 0.4 Fe2 O4] Spinel Ferrite
International Journal of Scientific Research in Science and Technology, 2021
Nano Ni-Zn ferrite with composition Ni 0.6 Zn 0.4 Fe2O4 is prepared by using sol-gel auto-combustion method with citric acid as a fuel. The structural properties of synthesized nano-ferrite is characterized by powder X-ray diffraction (XRD) technique while the electrical properties have been studied using two probe method. The X-ray diffraction study confirms that, there is a formation of single-phase cubic spinel with most intense peak at [311] having lattice constant of 8.3585 A0 and the average particle size is found to be 45.63 nm. In addition to this, the electrical resistivity of Ni-Zn Ferrite decreases with increase in temperature which exhibits semiconductor nature.
Structural and magnetic characterizations of MnNiZn ferrite nanoparticles
Physica Status Solidi A-applications and Materials Science, 2010
The ferrite samples of Ni0.7−xMnxZn0.3Fe2O4 (where x = 0.0–0.7 in steps of x = 0.1) were synthesized by a sol–gel autocombustion method using nitrates of respective metal ions. The synthesized samples were annealed at 600 °C for 4 h. The phase purity of the samples was investigated by X-ray diffraction (XRD). An analysis of XRD patterns reveals the formation of single-phase cubic spinel structure. The crystal lattice constant increases gradually with increasing x from 8.389 to 8.473 Å. The cation distribution of constituent ions shows linear dependence of Mn substitution. Based on the cation distribution obtained from XRD data, structural parameters such as lattice parameters, ionic radii of available sites, and the oxygen parameter “u” have been calculated. The trend of theoretically calculated lattice parameter with Mn content matches well with the experimentally obtained values. An initial increase followed by a subsequent decrease of saturation magnetization with increase in x is observed. Possible explanations for the observed structural and magnetic behavior with various Mn content are discussed.
Journal of Alloys and Compounds, 2011
Zinc doped nickel ferrite i.e., Ni 1−x Zn x Fe 2 O 4 (0 ≤ x ≤ 0.6) have been prepared by using sol-gel method. X-ray diffraction of these samples shows the presence of single-phase cubic spinel structure. The room temperature magnetic measurements showed that saturation magnetization (M s ) increases with the substitution of Zn 2+ ions up to x = 0.4 and thereafter it begins to decrease, whereas magnetostriction ( ) value decreases with the addition of Zn 2+ in the Ni-Zn ferrite. Dielectric permittivity (ε ), dielectric loss tangent (tan ı) and AC conductivity ( AC ) for all the prepared samples have been studied as a function of frequency and composition in the range from 0.05 Hz to 10 MHz at room temperature. It has been observed that initially ε , tan ı and AC decreases with the substitution of Zn 2+ up to x = 0.4 and then increases with the further addition of Zn 2+ ions. Variation in the slope parameter s with zinc contents indicates the presence of different type of conduction mechanism in different compositions. The dielectric loss curves exhibit relaxation peaks which shift with the addition of Zn contents. The results have been explained on the basis of space charge polarization according to Maxwell-Wagner's two-layer model and the hopping of charges between Fe 2+ and Fe 3+ as well as between Ni 3+ and Ni 2+ ions at the octahedral sites.