Nanomaterials & Nanotechnology
Stella C; Ramachandran K
Abstract
Undoped and Co3O4-loaded (5, 10, and 15 at.%) SnO2 nanoparticles were prepared by a simple co-precipitation method. X-ray diffraction (XRD) study confirmed the presence of tetragonal phase of SnO2 and cubic stage of Co3O4 in accumulation to this the preferred orientation and texture coefficient were ...
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Undoped and Co3O4-loaded (5, 10, and 15 at.%) SnO2 nanoparticles were prepared by a simple co-precipitation method. X-ray diffraction (XRD) study confirmed the presence of tetragonal phase of SnO2 and cubic stage of Co3O4 in accumulation to this the preferred orientation and texture coefficient were derived. The texture coefficient of (200) plane increases with parallel decrease in (110) plane, which indicate the development of voids like vacancies along (110) direction. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) analyses recognized the uniform dispersion of spherical shaped nanoparticles. EDS analysis confirmed the impurity absence in the prepared samples. UV-Vis absorption analysis confirmed that the optical band gap will get red shifted from bulk which is due to the agglomeration of nanoparticles and also due to the influences of Co3O4. The absorption peaks broadens after loading Co3O4 which indicate the surface related defects in the samples. The refractive indices derived from the band gap values had confirmed the fiber-optic sensor working under the leaky mode operation. Vibrating sample magnetometer (VSM) results confirmed the behavior of ferromagnet in pure SnO2 and antiferromagnet stage in Co3O4 loaded SnO2. The undoped SnO2 with room temperature ferromagnetism (RTFM) shows better sensitivity. The sensitivity of SnO2 and Co3O4 loaded SnO2 samples were 0.076 and 0.084, respectively. The enhanced sensitivity of Co3O4 loaded SnO2 was due to the high catalytic activity of Co3O4.
Sudip Pandey; Abdiel Quetz; Anil Aryal; Ahmad Us Saleheen; Igor Dubenko; Dipanjan Mazumdar; Shane Stadler; Naushad Ali
Abstract
The effects of substituting Cu for Mn on the magnetocaloric, transport, and thermomagnetic properties of Ni50Mn35-xCuxIn14B (x = 0, 1.25, 2.0) Heusler alloys were studied. It has been found that the magnitude of the magnetization jump at the martensitic transformation decreased with increasing Cu concentration. ...
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The effects of substituting Cu for Mn on the magnetocaloric, transport, and thermomagnetic properties of Ni50Mn35-xCuxIn14B (x = 0, 1.25, 2.0) Heusler alloys were studied. It has been found that the magnitude of the magnetization jump at the martensitic transformation decreased with increasing Cu concentration. Smaller magnetic entropy changes (∆SM) were observed for the alloys with higher Cu concentrations. A decrease in the resistivity was observed with increasing Cu concentration. The magnetoresistance was dramatically suppressed with increasing Cu concentration due to the weakening of the antiferromagnetic (AFM) interactions in the martensitic phase. The experimental results demonstrate that Cu in Ni50Mn35-xCuxIn14B Heusler alloys suppresses the AFM interactions and enhances the ferromagnetic (FM) interactions in these alloys. Possible mechanisms responsible for the observed behavior are discussed.
Seelam Harinath Babu; Shaik Kaleemulla
Abstract
To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles ...
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To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles were synthesized in quartz tube under reduced pressure at elevated temperature. The stoichiometric samples were crystallined in cubic bixbyite structure with change in the unit cell volume with Ni doping and shown average particle size of 50 nm in electron micrographs. Estimated energy band gap of Ni-doped ITO is found to be 3.15 eV. The magnetic properties of materials revealed that optimal doping of Sn gives highest magnetization and further increase of doping with Ni 2+ ions in In 3+ sites lead to deterioration of ferromagnetism induced by Sn 4+ . The observed ferromagnetism is attributed to the localized ferromagnetic exchange interactions induced by spin polarized electrons trapped in oxygen vacancies. The deterioration of ferromagnetism is attributed to excess anionic vacancies created by Ni doing and promotion of antiferromagnetic exchange with increase of Ni 2+ ion concentration as evidenced from magnetic hysteresis loop at 100 K.
M.Tanemura and P. K. Shishodia; M.Tanemura;P. K. Shishodia
Abstract
This paper reports the growth of Mn doped ZnO thin films by sol-gel technique with different Mn concentration (0-20 %). Structural and vibrational properties have been measured by X-ray diffraction and Raman spectroscopy. The films exhibit crystalline nature with (002) preferential orientation. The crystallite ...
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This paper reports the growth of Mn doped ZnO thin films by sol-gel technique with different Mn concentration (0-20 %). Structural and vibrational properties have been measured by X-ray diffraction and Raman spectroscopy. The films exhibit crystalline nature with (002) preferential orientation. The crystallite size and lattice parameters have been estimated as a function of Mn concentration. The Raman spectrum of the ZnO film shows the peaks corresponding to E2 (high) mode at 434 cm -1 assigned to Zn-O bond and A1 (LO) mode at 575 cm -1 . The elemental analysis of the films have been performed using X-ray photoelectron spectroscopy confirms the presence of Zn, O and Mn in doped films. Surface morphology and roughness of the films are observed by atomic force microscopy. The optical bandgap is found to decrease with Mn concentration as estimated by Tauc’s plots. Room temperature ferromagnetism has been obtained in ZnO: Mn thin films by superconducting quantum interference device.
M. C. Prestgard; G. P. Siegel; A. Tiwari
Abstract
In this article we have reviewed the role of oxides in spintronics research, and specifically how these materials stand to further improve the efficiencies and capabilities of spin injection for active spintronic device development. The use of oxides in spintronics is advantageous in that they are stable ...
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In this article we have reviewed the role of oxides in spintronics research, and specifically how these materials stand to further improve the efficiencies and capabilities of spin injection for active spintronic device development. The use of oxides in spintronics is advantageous in that they are stable in air, can be easily modified, and can possess a wide variety of properties which are beneficial to spintronics applications. This paper delineates the progression of spintronics and shows how applying oxide systems, in the form of half-metallic LaSrMnO3, the diluted magnetic semiconductor ZnO:Co, and diluted magnetic dielectrics CeO2:Co and Sm2O3:Co, has influenced and improved spintronics capabilities. An outline of the future potential for oxides in the realm of organic spintronic devices is also given
B. Sankara Reddy; S. Venkatramana Reddy; N. Koteeswara Reddy; Y. Prabhakara Reddy
Abstract
The (Fe, Ag) co-doped ZnO nanostructures are developed through chemical precipitation method at various percentages of Fe. The X-ray diffraction studies suggest that all the as-synthesized (Fe, Ag) doped ZnO nanopowders have single phase wurtzite structure with no secondary phases. However, the positions ...
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The (Fe, Ag) co-doped ZnO nanostructures are developed through chemical precipitation method at various percentages of Fe. The X-ray diffraction studies suggest that all the as-synthesized (Fe, Ag) doped ZnO nanopowders have single phase wurtzite structure with no secondary phases. However, the positions of diffracted peaks slightly shifted towards lower (2θ) angles. Photoluminescence studies reveal that 1 mol% of Fe doped ZnO sample has the best ultra violet (UV) emission properties than the other samples. On the other hand, 5 mol% of Fe doped ZnO nanopowders consists of strong green emission band, which belongs to oxygen interstitial defect states. Magnetization analysis shows that 5 mol% of Fe doped ZnO nanopowders have highest room temperature ferromagnetism (RTFM) than the RTFM of other samples. The observed RTFM in co-doped ZnO nanopowders is discussed with the help of structural and emission studies. The results strongly suggest the future development of efficient luminescence and magnetic materials at normal laboratory temperatures with (Fe, Ag) co-doped ZnO nanostructures.
Sukhdeep Singh; R.K. Kotnala;Kuldeep Chand Verma; Manpreet Singh; N.K. Ralhan
Abstract
Structural, microstructural, infrared analysis and magnetic properties of Ni1-x ZnxFe2O4 (NZ) [x = 0.30 (NZ30), 0.35 (NZ35) and 0.40 (NZ40)] nanoferrites have been thoroughly studied. These NZ nanoferrites were synthesized by chemical combustion route and annealed at 500 o C for 5h. Fourier transform ...
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Structural, microstructural, infrared analysis and magnetic properties of Ni1-x ZnxFe2O4 (NZ) [x = 0.30 (NZ30), 0.35 (NZ35) and 0.40 (NZ40)] nanoferrites have been thoroughly studied. These NZ nanoferrites were synthesized by chemical combustion route and annealed at 500 o C for 5h. Fourier transform infrared (FTIR) spectra of these samples were used to identify formation of Ni-Zn spinel ferrites. These FTIR results show two characteristic absorption bands corresponding to M-O intrinsic stretching vibrations at the tetrahedral site and octahedral-metal stretching around 570-550 cm -1 and 450-435 cm -1 , respectively. The X-ray diffraction shows the polycrystalline with spinel phase of these ferrites. The value of lattice constant a(Å) = 8.370, 8.371 and 8.380 respectively, for NZ30, NZ35 and NZ40 which are consistent with that reported for pure NiFe2O4. The average particles size is measured using Debye-Scherer’s relation which lies in the range of 25-65 nm. Transmission electron microscopy measured average grain size is 26, 41 and 66 nm, respectively for NZ30, NZ35 and NZ40 samples. The magnetic measurement shows saturation magnetization (Ms) of 67.63, 74.97, 80.63 emu/g, remanent magnetization (Mr) 20.01, 25.30, 25.30 emu/g and coercive field (Hc) 154.12, 154.13, 154.11 O e , respectively for NZ30, NZ35 and NZ40. Highest saturation magnetization with Zn doping has been observed in the case of NZ40.
Jaspreet Kaur; Jasneet Kaur; Jyoti Shah; R.K. Kotnala; Vinay Gupta; Kuldeep Chand Verma
Abstract
In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline ...
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In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline with cubic phase. The calculated value of distortion ratio (c/a) is ~ 1. No impurity or extra phase is observed. The micrographs by transmission electron microscopy reveal nanowires like structure of BFT1with diameter lie in the range of ~ 40 - 50 nm and length greater than 1.5 μm. The ME coefficient measurement shows that the ME coupling under the effect of both ac and dc bias. It shows strong dependence on ac and dc bias applied field. The value of linear coefficient (α) called ME coefficient is calculated as ~ 16 mV/Oecm at a fixed frequency of 850 Hz. This ME coefficient α corresponds to induction of polarization by a magnetic field or of magnetization by an electric field. The observed optimum dc bias field at which the maximum magneto-electric coupling occurs is ~ 750 Oe. The magnetization hysteresis shows strong ferromagnetism.
V. K. Sharma; G.D. Varma
Abstract
Bulk samples of Zn1-xFexO (x=0.02 and 0.05) were synthesized via solid state reaction route by sintering in air at 800 o C. Some sintered samples were annealed in Ar/H2 at 800 o C for ~ 5 hrs. X-ray diffraction results reveal that the basic crystal structure of the as sintered and hydrogenated (Ar/H2) ...
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Bulk samples of Zn1-xFexO (x=0.02 and 0.05) were synthesized via solid state reaction route by sintering in air at 800 o C. Some sintered samples were annealed in Ar/H2 at 800 o C for ~ 5 hrs. X-ray diffraction results reveal that the basic crystal structure of the as sintered and hydrogenated (Ar/H2) samples corresponds to ZnO wurtzite structure together with some traces of ZnFe2O4 in the as sintered and Fe metal in the hydrogenated samples. The as sintered samples of both compositions show paramagnetic behaviour and after hydrogenation they exhibit ferromagnetic interactions at room temperature. Increase in the electrical conductivity has also been observed in the hydrogenated samples. The presence of small Fe clusters in the hydrogenated samples are expected to be responsible for the observed room temperature ferromagnetism.
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