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Thakur A.,Shoolini University of Biotechnology and Management Sciences | Sharma P.,Shoolini University of Biotechnology and Management Sciences | Thakur P.,Shoolini University of Biotechnology and Management Sciences | Sharma A.,Innovative Science Research Society | And 3 more authors.
International Journal of Modern Physics B | Year: 2015

A nanoferrite series of composition Ni0.5-xMnxMg0.5Fe2O4 with x = 0, 0.1, 0.2, 0.3 and 0.4 has been prepared by a hydrothermal method. X-ray diffraction (XRD) confirmed the formation of cubic spinel structure. The average crystallite size is found to be in the range of 28-48 nm. The lattice parameter is found to increase linearly with an increase in Mn2+ content. Field Emission Scanning Electron Microscopy micrographs indicate that the samples have almost uniform sized crystallites with uniform grain growth. Fourier Transform Infrared (FTIR) Spectroscopy studies showed two absorption bands close to 603 and 400cm-1 for the tetrahedral and octahedral sites respectively. Saturation magnetization attained a maximum value of 34.15 emu/g at x = 0.3 and then decreases for higher concentrations of Mn2+ ions. Activation energy for compositions Ni0.3Mn0.2Mg0.5Fe2O4 and Ni0.2Mn0.3Mg0.5Fe2O4 are found to be 0.371 eV and 0.471 eV, respectively. For composition Ni0.2Mn0.3Mg0.5Fe2O4, maximum value of observed density, minimum porosity, maximum value of saturation magnetization, maximum initial permeability and minimum value of coercivity is obtained. DC resistivity is found to be of the order of 108Ocm. The obtained results have been explained based on possible mechanisms, models and theories. © 2015 World Scientific Publishing Company.


Pathania A.,Shoolini University of Biotechnology and Management Sciences | Thakur P.,Shoolini University of Biotechnology and Management Sciences | Sharma A.,Innovative Science Research Society | Hsu J.H.,National Taiwan University | Thakur A.,Shoolini University of Biotechnology and Management Sciences
Ceramics International | Year: 2015

Mn substituted ferrite series Ni0.5-x Mn x Mg0.5Fe1.98O4 with x=0.0, 0.1, 0.2, 0.3, 0.4 were prepared by a coprecipitation method. Samples were sintered at 600°C for 3h in a muffle furnace. Ferrite ceramics so obtained were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and Vibrating Sample Magnetometer (VSM) for their structural, morphological, optical and magnetic properties. XRD results confirmed cubic spinel structure with an average crystallite size in the range 33-47nm. FTIR spectra showed the two main absorption bands in the range 400-600cm-1 arising due to tetrahedral and octahedral stretching vibrations. Saturation magnetization increases with Mn2+ ion content, attains a maximum value of 35.7emu/g at x=0.2 and then decreases. This can be attributed to super exchange interactions between cations in the spinel- lattice upon Mn substitution. © 2015 Elsevier Ltd and Techna Group S.r.l.


Thakur S.S.,Government Post Graduate College | Thakur S.S.,Himachal Pradesh University | Pathania A.,Himachal Pradesh University | Pathania A.,Innovative Science Research Society | And 3 more authors.
Ceramics International | Year: 2015

Cd doped Mn-Zn nanoferrites of the composition Mn0.4Zn0.6CdxFe2-xO4, with (0.000.5) have been synthesized by a co-precipitation method. The X-ray diffraction patterns of the samples confirmed the formation of a single-phase cubic spinel structure. Average crystallite size is found to be in the range of 35-40 nm, which is in consistence with transmission electron microscopy results. The average grain size as calculated from scanning electron microscopy is found to be 100 nm. DC resistivity is found to be about 10 times higher than the reported values. Specific saturation magnetization is observed to be increasing from 25.23 emu/g to 48.93 emu/g with cadmium concentration. Magnetic moment is increasing from 1.07 BM to 2.35 BM with increasing concentration of Cd2+ ions. Variation of anisotropy constant as a function of concentration of doping is also discussed. Comparatively higher DC resistivity, refined crystallite size and improved magnetization are the main achievements of the present investigation. © 2014 Elsevier Ltd and Techna Group S.r.l.


Pathania A.,Shoolini University of Biotechnology and Management Sciences | Pathania A.,Himachal Pradesh University | Rana K.,Himachal Pradesh University | Rana K.,Innovative Science Research Society | And 7 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2016

In this study, tungsten substituted Ni-Zn nano ferrites of the composition Ni0.5Zn0.5WxFe2−xO4 with x = 0.0, 0.2, 0.4 have been synthesized by a co-precipitation method. The prepared samples were pre-sintered at 850 °C and then annealed at 1000 °C for 3 h each. The structural, morphological, optical and magnetic properties of these samples were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS) and Mössbauer spectroscopy (MS). XRD revealed the formation of spinel single-phase structure with an average crystallite size of 53–60 nm. Fourier transform infrared spectroscopy show two prominent peaks primarily due to the tetrahedral and octahedral stretching vibrations in the range of 400–600 cm−1. Raman spectra indicate first order three Raman active modes; (A1 g + Eg + T2 g) at around 688, 475 and 326 cm−1. Mössbauer spectroscopy reveals that substitution of W3+ for Fe3+ cation results in reduction of total magnetic moment and consequently the net magnetization. © 2016 Springer Science+Business Media New York


Sharma P.,Shoolini University of Biotechnology and Management Sciences | Thakur P.,Shoolini University of Biotechnology and Management Sciences | Mattei J.L.,CNRS Communication and Information Sciences Laboratories | Queffelec P.,CNRS Communication and Information Sciences Laboratories | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2016

A series of cobalt substituted lithium ferrite Li0.5CoxFe2.5-xO4 with x=0, 0.2, 0.4 was prepared by a chemical technique called citrate precursor method. In this technique citric acid was used as a reducing agent. Structural, morphological, topographical, optical, electrical, and magnetic properties were studied by using X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, DC resistivity, Mössbauer Spectroscopy. XRD patterns showed characteristic (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), (4 4 0) peaks which confirmed the inverse spinel phase. SEM and TEM support the formation of cubic nanoparticles. FTIR studies reported the ferrite peaks between 400 cm-1 and 800 cm-1 confirming the inverse spinel structure. Five optical Raman modes (A1g+Eg+3F2g), characteristics of the cubic spinel structure with (P4332) space group are also observed. Electrical DC resistivity studied from room temperature to 300°C showed the semiconducting behavior of lithium ferrite. Porosity, transition temperature and activation energy are found to decrease with cobalt ion concentration. The room temperature Mössbauer spectra of all the samples showed normal Zeeman Splitting sextets supporting the formation of ferromagnetic phase. With increase in cobalt content, the value of hyperfine field at A site is found to vary from 53.15 to 54.96 T whereas at B site it vary from 54.79 to 52.82 T. The obtained results have been explained based on possible mechanisms, models and theories. © 2016 Elsevier B.V. All rights reserved.


Rana K.,Shoolini University of Biotechnology and Management Sciences | Thakur P.,Shoolini University of Biotechnology and Management Sciences | Thakur A.,Shoolini University of Biotechnology and Management Sciences | Thakur A.,Innovative Science Research Society | And 4 more authors.
Ceramics International | Year: 2016

Sm doped Ba-Co hexaferrite with composition BaCo0.8Sm x Fe(11.2-x) O19 (x=0.2, 0.4 and 0.6) were prepared via a citrate precursor method. After appropriate heat treatments, the ferrite samples were characterised by using different measurement techniques. X-ray diffraction (XRD) confirmed the formation of M phase with an average crystallite size of 35-45nm. Observed tensile strain leads to the elongation of Ba-Co grains and was calculated using Williamson Hall plot. Surface morphology of these samples was studied by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). σ-H loops of these samples were measured at room temperature up to an applied field of 22,000Oe using vibrating sample magnetometry (VSM). With an increase in concentration of Sm ions in Ba-Co lattice, specific saturation magnetisation (σ s), coercivity (H c) and retentivity (σ r) values were found to decrease. At x=0.2, excellent values of H c (2690.20Oe) and squareness ratio (SQR=0.5619) were simultaneously found. These parameters make this material a promising candidate for the applications such as high density magnetic recording and enhanced memory storage. © 2016 Elsevier Ltd and Techna Group S.r.l.


Thakur A.,Shoolini University of Biotechnology and Management Sciences | Kumar P.,Shoolini University of Biotechnology and Management Sciences | Kumar P.,Innovative Science Research Society | Thakur P.,Shoolini University of Biotechnology and Management Sciences | And 4 more authors.
Ceramics International | Year: 2016

Nano crystalline Ni-Zn ferrites of composition Ni0.5Zn0.5Fe2O4have been prepared by a chemical co-precipitation method. The powdered samples were sintered at a temperature of 800°C and 900°C for three hours. X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to study their structural and morphological changes. The enhanced magnetic properties were investigated by using a Vibrating Sample Magnetometer (VSM). The saturation magnetization was found to increase from 73.88 to 89.50emu/g as a function of sintering temperature making this material useful for high frequency applications. Electromagnetic studies showed sustained values of permittivity up to 1GHz. These results have been explained on the basis of various models and theories. © 2016 Elsevier Ltd and Techna Group S.r.l.


Saini A.,Terminal Ballistics Research Laboratory | Saini A.,Shoolini University of Biotechnology and Management Sciences | Rana K.,Shoolini University of Biotechnology and Management Sciences | Rana K.,Innovative Science Research Society | And 4 more authors.
Materials Research Bulletin | Year: 2016

Miniaturization of patch antenna using composite ferrite (Ni0.5Zn0.3Co0.2Fe2O4 + BaFe12O19) is proposed in this paper. Substrate material was prepared using a wet chemical method and characterized for its structural and electromagnetic properties. Matching values of complex permittivity (ε∗= 4.5 + 0.1 j) and complex permeability (μ∗= 4.6 + 0.3 j) at 500 MHz were obtained from the electromagnetic characterization. Simulation result showed that matching and greater than unity value of both permittivity and permeability can reduce the size of antenna by almost 55%. Normalized characteristic impedance close to unity (∼1.022) was observed in the synthesized nano ferrite composites. This results in better impedance matching of the substrate with the surrounding space. Reflection loss was found to decrease (from -28 dB to -35 dB) and bandwidth increases (1.6-6%) over pure dielectric substrate. Therefore, composite ferrite is proposed as suitable candidate for effective miniaturization of antenna in microwave frequency range. © 2015 Elsevier Ltd.

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