Structural , Electrical and Dielectric Behavior of NixCo 1-xPryFe 2-yO 4 Nano-Ferrites Synthesized by Sol-Gel Method (original) (raw)
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The influence of neodymium (Nd) contents on the structural, electrical and dielectric properties of Nickel cobalt ferrites was studied in the ferrite series NixCO1-xNdyFe2-yO4 (x= 0.00, 0.20, 0.40, 0.60, 0.80, 1.0 and y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.1). This series was prepared by sol-gel method. XRD analysis reveals single phase samples up to y=0.04. At y ≥ 0.06, a secondary phase of iron neodymium oxide (NdFeO3) appears along with the spinel phase. The incorporation of Nd3+ for Fe3+ ions results in a slight increase of lattice constant due to larger ionic radius of the substituted ions. It was inferred that the substitution of neodymium limits the grain growth. The DC electrical resistivity and activation energy are higher for the substituted samples. The dielectric constant, dielectric loss (tan δ) and AC-conductivity decreased on account of doping. The decrease in dielectric constant is imputed to the reduction in the internal viscosity of the doped samples. The dielectric data are explained on the basis of space charge polarization. Ferrites have high dielectric constant and low tan δ, they may be attractive for application in switching and memory storage devices.
2020
In the present work, Ni0.6Cd0.4DyxFe2‒xO4 (x = 0.0, 0.05, 0.10, 0.15 and 0.20) nanoparticles (NPs) were synthesized by using sol-gel auto combustion method. The structural characterization was performed by XRD, FTIR, SEM, TEM and EDS analyses. XRD patterns confirmed that the pure and dysprosium substituted Ni-Cd ferrites are in single phase spinel structures, while a trace of DyFeO3 appears as a minor phase for higher concentrations (x = 0.10, 0.15 and 0.20). The Debye‒Scherrer’s method and Williamson-Hall (W-H) method were used to evaluate the crystallite sizes and lattice strain. The average crystallite size was found to be in the range from 27 to 48 nm. FT-IR confirms the formation of spinel structure. SEM images show that reduction of grain size with Dy3+ content. Elemental composition features of samples were examined by EDS. The average particles size estimated from TEM analysis are in good agreement with results obtained from the XRD. The results showed that saturation magnet...
JOURNAL OF NANOSCOPE (JN)
This research article reveals the effect of Dy +3 substitution on ?-ferrites KFe 11-x Dy x O 17 with composition (x=0.00, 0.25, 0.50, 0.75 and 1.0). The samples were synthesized by sol-gel auto- combustion method, sintered at 950 o C temperature. The XRD patterns confirmed the single phase of the synthesized samples. The crystallite size varied in the range of 21.49 nm to 25.24 nm for all samples. The polarization verses electric field (P-E) loops indicated the loosy behavior in all samples. The lossy behavior of the samples was seemed to be increased up to x=0.5 and then decreased. The theoretical expression was used to fit an upper branch of P-E loops. FT-IR spectra showed absorption bands at different wavenumbers due to M-O-M stretching vibrations, H-O-H stretching, and C-O-C stretching vibrations, which also confirmed the formation of the single-phase in the samples. Electrochemical measurements of synthesized nano ferrites were carried out by using cyclic voltammetry in a 3.0 M...
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In the present paper, the experimental and theoretical properties of (Sr 1 À x Ca x) MnO 3 (0 rx r 1.0) are reported. The lattice parameter and cell volume of both monoclinic [P 2 /m] and orthorhombic [Pbnm] phases of strontium calcium manganite have been calculated by using first principle calculation method. These calculated and experimental values match with each other. The dielectric constant and dielectric loss of (Sr 1 À x Ca x) MnO 3 (0 rx r 1.0) as function of frequency (20 Hz to 1 MHz) at room temperature as well as function of temperature (30-400 1C) at a frequency of 1.2 kHz are reported. This result shows the poly-dispersive nature of the system. The impedance, conductivity and electric modulus as a function of frequency have been studied.
Electric and dielectric properties of ytterbium substituted spinel ferrites
Journal of Materials Science: Materials in Electronics, 2017
Ytterbium (Yb) substituted magnesium ferrite materials (MgYb x Fe 2−x O 4 with x = 0.00, 0.025, 0.050, 0.075, 0.10) have been prepared by the Sol-gel method. XRD analysis revealed that the prepared samples are cubic spinel with single phase till the content 'x' equals 0.05. At higher content x ≥ 0.075, Yb substituted samples possessed YbFeO 3 phase along with the cubic spinel phase. A significant decrease of ~34.7 nm in crystallite size is noted in response to the increase in Yb substitution level. The room temperature dc resistivity increases gradually from 3.47 × 10 7 to 2.63 × 10 8 Ω-cm as the substitution of Yb is increased. Temperature dependent DC electrical resistivity of all the samples exhibits semiconducting behavior. Yb substituted materials can be suitable to limit the eddy current losses for microwave applications. VSM indicated the existence of an appreciable fraction of ferrimagnetic properties at room temperature. The saturation magnetization of the samples decreases from 60 to 33 emu/g. Saturation magnetization and remanence decreased while coercivity increased with Yb substitution.
Materials Letters, 2008
AC conductivity, density related and magnetic properties are reported for Ni 1 − x Zn x Fe 2 O 4 ferrites with the variation of zinc concentration prepared by the standard solid state reaction technique. X-ray powder diffraction patterns confirmed the spinel structure of the prepared compounds. AC conductivity (lnσ ac ) increases from −10.045 (S/m) to −3.781 (S/m) with the increase in zinc concentration from 0.0 to 1.0 at the frequency of 1 kHz. Lattice parameters, sintered density and grain size increase whereas X-ray density and porosity decrease with the increase in zinc concentration. Saturation magnetization increases with the increase in zinc concentration up to x = 0.4 and after that it decreases with the increase in zinc concentration. Remanence magnetization and magnetic moment almost have the similar trend as that of saturation magnetization. Yafet-Kittel angles increase with the increase in zinc concentration. The possible reasons responsible for these changes are undertaken.
Dielectric relaxation behavior of AxCo1−xFe2O4 (A = Zn, Mg) mixed ferrites
JALCOM 2012
Samples of A x Co 1−x Fe 2 O 4 (A = Zn, Mg; x = 0.0, 0.5) ferrite were synthesized by chemical co-precipitation method. Room temperature Rietveld -refined X-ray diffraction pattern elucidate the formation of singlephase cubic structure with Fd3m space group for all prepared samples. Slight variation in the lattice parameter of Mg doped CoFe 2 O 4 has been observed when compared with CoFe 2 O 4 and Zn 0.5 Co 0.5 Fe 2 O 4 . The variation of permittivity and ac conductivity as a function of frequency reveals that dispersion in all these ferrites is attributed to Maxwell-Wagner type of interfacial polarization. The minimum value of loss tangent (∼0.04) at 5 kHz makes A x Co 1−x Fe 2 O 4 most suitable material for microwave application. Temperature dependent dielectric constant and loss tangent of all the three samples shows an increasing trend with increase in temperature. The activation energy (E a ) for CoFe 2 O 4 , Co 0.5 Mg 0.5 Fe 2 O 4 and Co 0.5 Zn 0.5 Fe 2 O 4 were found to be 0.81 eV, 0.76 eV and 0.63 eV respectively. The electrical modulus study clearly reveals the presence of non-Debye type of dielectric relaxation in the present material.
Cation distribution in nanocrystalline NixZn1−xFe2O4 spinel ferrites
Inorganic Materials
We have studied the cation distribution over the tetrahedral and octahedral sites in the spinel structure of nanocrystalline NixZn1−xFe2O4 ferrites prepared by spray pyrolysis. 57Fe Mössbauer spectroscopy data for the ferrites demonstrate that, depending on the composition of the materials, the tetrahedral site may accommodate only Fe3+ (inverse spinel, x ≥ 0.4) or both Fe3+ and Zn2+ cations (mixed spinel, x = 0 and 0.2), which accounts for the fact that the composition dependence of the unit-cell parameter for the ferrites deviates from Vegard’s law.
Journal of Magnetism and Magnetic Materials, 2015
A series of the divalent and trivalent co-substituted Mg 0.5 À x Cd x Co 0.5 Cr 0.04 Tb y Fe 1.96 À y O 4 spinel ferrite systems (where x ¼ 0-0.5 in steps of 0.1 and y ¼0.00-0.10 in steps 0.02) are synthesized by sol-gel auto combustion method. The product materials were characterized by the thermo gravimetric analysis and differential scanning calorimetry (TGA/DSC), Fourier transform infrared spectra (FTIR), nitrogen adsorption (BET), X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The X-ray diffraction patterns and Fourier transform infrared spectroscopy confirm spinel nanocrystalline phase. The crystallite size is determined by Scherer's formula from 36.6 to 69.4 nm. The X-ray density is found in the range of 5.09-6.43 (g/cm 3 ). The morphological features are studied using scanning electron microscope and AFM. Saturation magnetization (M s ) and remanence (M r ) magnetization extracted from M-H loops exhibit the decreasing trends 21.4-16 emu/g and 9.1-6.3 emu/g, respectively. A significant decrease in the intrinsic parameters is observed in the prepared samples due to the weakening of the A-B interaction as iron enters into the tetrahedral A-site. The coercivity lies in the range of 300-869 Oe as a function of co-substitution contents. The coercivity of the sample with x ¼0.1, y¼ 0.02 was found maximum i.e. 869 Oe. The obtained results suggest that the investigated materials may be potential candidates for high density recording media applications.