Slawomir M. Kaczmarek; Tomasz Bodziony; Vinh H. Tran; Pawal Figiel; Anna Biedunkiewicz; Grzegorz Leniec
Abstract
Series of nanocrystalline and TiC, TiB2, and B4C powders as dopants (3%-20%) embedded in an AISI 316L austenitic steel have been prepared and investigated by ferromagnetic resonance and magnetic measurements. The homogeneous composites with the dopants up to x = 7 vol. % exhibit superparamagnetic properties, ...
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Series of nanocrystalline and TiC, TiB2, and B4C powders as dopants (3%-20%) embedded in an AISI 316L austenitic steel have been prepared and investigated by ferromagnetic resonance and magnetic measurements. The homogeneous composites with the dopants up to x = 7 vol. % exhibit superparamagnetic properties, characterized by bifurcation between the field-cooled MFC(T) and zero-field cooled MZFC(T) magnetization below Tir and a maximum at Tmax in low-field MZFC(T) curves. We found that the Tir and Tmax values depend proportionally on the dopant concentrations x. The magnetization measurements in fields above 1000 Oe suggested an induced phase transition from superparamagnetic state to ferromagnetic one but presumably without long-range magnetic correlation. An analysis of magnetic anisotropic energy barrier distributions implied that different sizes and compositional types of dopants may contribute to the superparamagnetic relaxation process. The results demonstrate the possibility of obtaining new steel-based materials with desired properties and potential applications as combining magnetic and mechanical advantages.
Amrita Das; Vishal Shama
Abstract
In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to ...
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In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to one, with varying concentration of Eu 3+ ions acting as an activator. The prepared powder showed excellent thermal stability. For the identification of the phase and structure of the powder synthesized, X-ray diffractometer was used. From the XRD analysis, it is revealed that the rhombohedral crystallite phase of α-alumina was formed. The type of morphology and particle size was ascertained by Filed Emission-Scanning Electron Microscope (FE-SEM) and it was found that particles were having irregular spherical shape. A qualitative analysis of these nanophosphor particles was made using an Energy dispersive X-ray detector (EDS) and it was found that the samples were composed of Al, O and Eu ions. Photo-luminescence (PL) spectra were obtained using Spectrofluorometer absorption. The intense band position was observed at 618 nm and other less intense bands were also seen at 592 nm, 601 nm, 631 nm, while two weak bands were observed at 660 nm and 718 nm, when excited at 226 nm. The CIE color space chromaticity diagram was calculated from the CIE Calculator program using obtained PL spectra. The prepared nanophosphor powder was tested for latent fingerprint detection in forensic applications. The synthesized nanophosphor was successfully used as a latent fingerprint developing powder on various non-porous surfaces for forensic application.
Preetam Singh; K. M. K. Srivatsa;Sourav Das
Abstract
Single oriented nanocrystalline CeO2 thin films have been deposited over Si (100) substrate by RF magnetron sputtering in the temperature range 600-700 o C, using CeO2 target. X-ray diffraction pattern for the as deposited CeO2 film at 700 o C shows the dominant (111) orientation with corresponding FWHM ...
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Single oriented nanocrystalline CeO2 thin films have been deposited over Si (100) substrate by RF magnetron sputtering in the temperature range 600-700 o C, using CeO2 target. X-ray diffraction pattern for the as deposited CeO2 film at 700 o C shows the dominant (111) orientation with corresponding FWHM value of 0.378 o and the crystallite size 21.50 nm. The refractive index and the optical band gap both were found to increase from 2.35 to 2.66 and 3.25 to 3.43 eV, respectively with increasing substrate temperature. Atomic force microscopy results reveal highly smooth surface of the deposited films with surface roughness below 1.15 nm for the entire range of deposition temperatures. Further, the contact angle measurements on the as deposited CeO2 films showed variation from 122.36 to 81.67 o with respect to the substrate temperature, transforming the wetting property from hydrophobic to hydrophilic in nature. These results indicate the possibility of producing CeO2 films with varying properties for various device applications simply by controlling the substrate temperature.
Usha Chandra; K. Asokan; V. Ganesan
Abstract
Nanocrystalline stoichiometric La0.8Sr0.2Mn0.8Fe0.2O3 manganites synthesized by sol gel technique were irradiated by 200 MeV Ag +16 ion beam at various fluences and investigated by X-ray diffraction (XRD), magnetization and high resolution Mössbauer spectroscopic techniques. The analysis of Mössbauer ...
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Nanocrystalline stoichiometric La0.8Sr0.2Mn0.8Fe0.2O3 manganites synthesized by sol gel technique were irradiated by 200 MeV Ag +16 ion beam at various fluences and investigated by X-ray diffraction (XRD), magnetization and high resolution Mössbauer spectroscopic techniques. The analysis of Mössbauer patterns were done using Kopcewicz et al. (2004) proposition considering Double exchange mechanism. Both XRD and Mössbauer spectroscopic analysis indicated isostructural vacancy formation at Mn site at the fluence 5x10 12 ions/cm 2 . The system showed amorphous phase at the higher fluence of 1x10 13 ions/cm 2 . The local electronic environments seen through high resolution Mössbauer spectroscopic technique on the irradiated systems were understood in terms of ferromagnetic coupling between different Mn environment surrounding Fe ions. This proposition is supported by enhanced magnetization observed in the irradiated samples (Kopcewicz et al., 2004). The similarity to the hydrostatic applied pressure (at low value) is seen through the transformation from Fe 4+ to Fe 3+ at low fluence.
S.R. Mane; P.S. Patil;P. N. Bhosale; R. M. Mane
Abstract
Thallium (I) doped tungsten heteropolyoxometalate (HPOM) combinatorial thin films have been deposited on glass substrate using simple chemical bath deposition technique. The deposited films were annealed at 100 o C, 150 o C, 200 o C and 250 o C. These annealed thin films were characterized by using SEM, ...
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Thallium (I) doped tungsten heteropolyoxometalate (HPOM) combinatorial thin films have been deposited on glass substrate using simple chemical bath deposition technique. The deposited films were annealed at 100 o C, 150 o C, 200 o C and 250 o C. These annealed thin films were characterized by using SEM, EDAX, AFM, FT-IR, XRD and TGA-DTA techniques for their structural properties. SEM and EDAX results shows that, tungsten HPOM material is polycrystalline in nature and Tl (I) is intercalated in phosphotungustate anion. AFM studies on the films annealed at different temperatures reveal that the surface roughness increases with the increase in annealing temperature, suggesting an increase of crystallization with temperature. FT-IR study confirms the well formation of heteropolyoxometalate material under investigation. Various structural parameters such as lattice constants, crystallite size and grain size have been calculated and they are found temperature dependent. The lattice constant, crystallite size and grain size of tungsten HPOM material increases with increase in temperature. XRD pattern of annealed thin films shows better crystanality of tungsten HPOM material having simple cubic spinel structure. The TGA-DTA study revealed that, Tl3 (PW12 O40) material is thermally stable up to 265.12 o C.
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