Investigation of structural, electrical, electrical polarization and dielectric properties of CTAB assisted Ni2+ substituted R-type nano-hexaferrites (original) (raw)

The Nb3+ ion substituted Sr hexaferrites (SrNbxFe12−xO19 (x = 0.00-0.08) hexaferrites (HFs)) were fabricated via a citrate-assisted sol-gel approach. X-ray powder diffractometer analysis affirmed the pureness of all products. The crystallite sizes of the products which were estimated from Scherrer equation were in the 36-40 nm range. The chemical component of the samples was proved by Energy-dispersive X-ray spectroscopy (EDX) and Elemental mapping. The hexagonal morphology of all products was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM). The electrical conduction mechanisms and dielectric properties of a variety of Nb3+ions-substituted SrNbxFe12−xO19 HFs were investigated by a complex impedance system. Dielectric parameters such as conductivity, dielectric constant, dielectric loss, dielectric tangent loss and complex modulus, were studied at temperatures up to 120 • C in a frequency range varying from 1.0 Hz to 3.0 MHz for several Nb ratios. The frequency dependence of the conductivity was found to comply with the power law with diverse exponents at all frequencies studied here. Subsequently, incremental tendencies in dc conductivity with temperature indicate that the substituted Sr-HFs leads to a semiconductor-semimetal like behavior. This could be attributable to a feature of conduction mechanism which is based on the tunneling processes. Additionally, the dielectric dispersion pattern was also explained by Maxwell-Wagner polarization in accordance with the Koop's phenomenological theory.

In the present investigation we synthesized a series of polycrystalline Y-type SrNiZn nano hexa ferrites substituted with TiCo having generic formula Sr2NiZnFe12-X(TiCo)X/2O22 (where x = 0.0, 0.5, 1.0, 1.5) by novel microwave assisted sol-gel auto combustion route. Structural analysis of the compounds has been studied using X-ray powder diffraction pattern. The prepared compounds are in

A series Manganese and Gadolinium doped Zinc-Strontium hexaferrites, Sr2Zn2 − xMnxFe12− Sr2Zn2 − xMnxFe12−yGdyO22 (x = 0.0–1.0, y = 0.0-0.1), was fabricated by chemical co-precipitation route. XRD analysis confirmed the single magnetoplumbite phase formed in hexaferrites with average crystallite size in the range 27–38 nm. Surface morphology and size distribution was also explored using Scanning electron microscopy (SEM). The dielectric parameters i.e. dielectric constant, dielectric loss and dielectic tan loss were measured at ambient temperature and in 1.0 MHz to 3.0 GHz frequency range. Mn-Gd substituted Zn-Sr hexaferrites showed independent trend of dielectric parameters with frequency upto a certain value beyond which resonance type behavior was observed. The dielectric parameters initially decrease with frequency then become almost constant followed by resonance type behavior. Subsitution of Mn and Gd resulted in sharp decrease of dielectric parameters followed by gradual incr...

A series of Ni1−x Cox Fe2O4 (x=0.1, 0.2, 0.3, 0.4, 0.5) spinel ferrites have been synthesized successfully using the chemical co-precipitation route. The materials were characterized by X-rays powder diffractometry (XRD) and the electrical properties. The obtained crystallite size variation was within 15 to 33 nm using the Scherrer formula. The dc electrical resistivity was measured as a function of temperature. It is noticed that σ dc increases with a rise in temperature. The dielectric measurements were carried out at room temperature as a function of frequency and composition (x). The dielectric constant (ε′) and dielectric loss tangent (tan δ) showed a decreasing trend with increasing field frequency. The ac electrical conductivity is calculated from the dielectric measurements; it increases with the rise in frequency.

Nanoscale Ni0.7-xCu0.3MgxFe2O4 (0.0 ≤ x ≤ 0.5) powders were prepared by sol-gel synthesis with M= Ni, Cu, Mg. they are obtained as dried gel after the successful reaction of their respective metal nitrates. X-ray diffraction method confirmed the successful synthesis of the materials. The average particle size of these materials has been found between 19-26 nm. Dielectric constant (ε ) decreases with increase in frequency which is rapid at lower frequencies and slower at higher frequencies which may be due to Maxwell-Wagner interfacial polarization. Dielectric relaxation peaks were observed in the lower concentration for frequency dependence of dielectric loss tangent curves.

Ba-hexaferrites of composition (BaO)1−x (La2O3)x 5.7 Fe2O3, where x = 0.00, 0.04, 0.08 and BaO 5.7 Fe2O3 + [0.7 wt% CaO + 0.3 wt% SiO2] were prepared by standard double sintering ceramic technology using magnetite from Cox’s Bazar beach sand, Bangladesh. In this work, magnetic, dielectric and electrical properties of Ba-hexaferrites with and without additives have been reported. Measurements of permeability, loss factor, quality factor (Q-factor), resistivity and dielectric constant of the synthesized samples have been carried out. Permeability remains unaltered in the observed frequency range. The loss factor increases with the increase in temperature and additives as well. It has been observed that the loss factor decreases with the increase in frequency. The Q-factor decreases with the increase in temperature and increases with the increase in frequency. The dielectric constant decreases with the increase in frequency. The ac resistivity of Ba-hexaferrites increases with the increase in additive contents.