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Gadkari A.B.,GKG college | Shinde T.J.,KRP Kanya Mahavidylaya | Vasambekar P.N.,Shivaji University
Journal of Materials Science: Materials in Electronics | Year: 2010

Polycrystalline spinel ferrites with general formula Mg 1-xCd x Fe 2O 4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by oxalate co-precipitation method using high purity sulfates. The samples were sintered at 1,050 °C for 5 h. The structural properties of these samples were investigated by XRD, SEM and FTIR techniques. The X-ray diffraction analysis confirms the formation of single phase cubic spinel structure of all the samples. The lattice constant, X-ray density, physical density, porosity, crystallite size, site radii (r A, r B), bond length (A-O, B-O) on tetrahedral (A-site) and octahedral (B-site) were calculated for the samples. The lattice constant increases with increase in Cd 2+ content. The X-ray density increases with increase in Cd 2+ content. The crystallite size calculated by Scherrer formula is in the range of 27.79-30.40 nm. Physical densities are calculated by Archimedes principle. The SEM study shows that the grain size increases with increasing Cd 2+ content. The FTIR spectra shows two strong absorption bands around 576 and 431 cm -1 on the tetrahedral and octahedral sites, respectively. The dependence of saturation magnetization on Cd 2+ content suggests that A-B and B-B super exchange interaction are comparable in strength. Neel's two sub lattice model is applicable up to x ≤ 0.4, while Y-K three sub lattice models (canted spin) is predominant for x ≥ 0.4. Copyright © 2009 Springer Science+Business Media, LLC. Source


Gadkari A.B.,GKG college | Shinde T.J.,KRP Kanya Mahavidylaya | Vasambekar P.N.,Shivaji University
Journal of Magnetism and Magnetic Materials | Year: 2010

Nanocrystalline ferrite powder having the general formula Mg 1-xCdxFe2O45% Sm3 (x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) was synthesized by chemical oxalate co-precipitation technique. The synthesized powder was characterized by X-ray, IR and SEM techniques. The XRD analysis confirms cubic spinel phase with orthoferrite secondary phase. The lattice constant increases with increase in Cd2 content (x). It is smaller than that for pure MgCd ferrites. The average crystallite size lies in the range 28.6932.66 nm. Saturation magnetization and magnetic moment increase with cadmium content up to x=0.4 and decrease thereafter. This is attributed to the existence of localized canted spin. The decrease in saturation magnetization and magnetic moment beyond x=0.4 is due to the presence of triangular spin arrangement on B-site. Coercivity and remanent magnetization decrease while YK angles increase with Cd2 content. The Sm3 addition improves the magnetic properties. © 2010 Elsevier B.V. All rights reserved. Source


Ashok B.G.,GKG college | Tukaram J.S.,KRP Kanya Mahavidylaya | Pramod N.V.,Shivaji University
Advanced Materials Research | Year: 2013

Nanocrystallite powders of 5 wt% Sm3+ added Mg-Cd ferrite samples were prepared by oxalate co-precipitation method. XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD reveals cubic spinel nature with secondary phase (SmFeO3). The crystallite size lies in the range of 28.69 to 32.66 nm. All the Sm3+ ions added samples are humidity sensitive at low humidity range 40 to70%RH. The electrical resistivity of Sm3+ ions added samples decreased by four orders of magnitude, when %RH increased from 40%RH to 90%RH. The response and recovery time of all the samples are 160-290 sec. The shorter response time was observed for Sm3+ added Cd ferrite sensor. © (2013) Trans Tech Publications, Switzerland. Source


Gadkari A.B.,GKG college | Shinde T.J.,KRP Kanya Mahavidylaya | Vasambekar P.N.,Shivaji University
Materials Research Bulletin | Year: 2013

The samples having general formula Mg1-xCdxFe 2O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) with 5% Y 3+ addition were prepared by oxalate co-precipitation technique. The characterization was carried by XRD, SEM and FTIR techniques. The XRD confirms the cubic spinel structure with orthoferrite (YFe2O3) secondary phase. Average crystallite size and grain size lies in the range (28.86-32.66 nm and 0.37-0.69 μm). The grain size is calculated by linear intercept method and lies in the range of 0.37-0.69 μm. The FT-IR shows two absorption bands in the frequency range of 350-800 cm-1. The addition of Y3+ for Fe3+ forms a secondary phase on the grain boundaries and increases the saturation magnetization with respect to that of pure MgCd ferrites. The saturation magnetization, magnetic moment and coercive field is found to increase with cadmium content up to x = 0.4, obeying Neel's two sublattice model and decrease thereafter showing existence of non-collinear spin interaction. The saturation magnetization and coercivity shows size dependent behavior. Y-K type ordering is present in all samples except x = 1. The DC electrical resistivity increases while the Curie temperature (T c) decreases, with increase in cadmium content. The DC resistivity of Y3+ added MgCd ferrite is higher than that reported for pure samples and for ceramic method. Activation energy in paramagnetic region is higher than that in ferromagnetic region. © 2012 Elsevier Ltd. Source


Gadkari A.B.,GKG college | Shinde T.J.,KRP Kanya Mahavidylaya | Vasambekar P.N.,Shivaji University
Sensors and Actuators, B: Chemical | Year: 2013

5 wt% Sm3+ added nanocrystallite ferrite samples with general formula Mg1-xCdxFe2 O4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by oxalate co-precipitation method from high purity sulphates. The XRD, SEM and FT-IR techniques were used for characterization of the samples. The XRD confirms cubic spinel structure with orthoferrite (SmFeO3) secondary phase. The crystallite size varies from 28.69 to 32.66 nm. The surface morphology SEM study shows increase in grain size with Cd2+ concentration, while it decrease due to Sm 3+ addition in Mg-Cd ferrites. The FT-IR spectra show two strong absorption bands in the range of 350-800 cm-1. The response decreases with Cd2+ concentration for LPG, Cl2 while increases for C2H5OH. The response of Sm3+ added Mg-Cd ferrite is higher than Mg-Cd ferrite. The response and recovery time of Sm 3+ added Mg-Cd ferrites decreases with increase in Cd2+ concentration and lower than Mg-Cd ferrites. The shorter response and recovery time is observed for Sm3+ added Cd ferrite sensor compared to other samples. The response depend on the composition, test gas and grain size of the material. © 2012 Elsevier B.V. Source

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