• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.135-139
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• 2014

Iron-oxide nanopowders were synthesized by a pulsed wire evaporation (PWE) in various ambient gas conditions. SEM measurement indicates that the spherical iron nanoparticles are about 50 nm in diameter. The phase analysis for the produced iron-oxide powders was systematically investigated by using $M\ddot{o}ssbauer$ spectra and the results show that classified phases of $Fe_2O_3$ and $Fe_3O_4$ can be controlled by regulating the oxygen concentration in the mixed gas during the PWE process. A quadrupole line on the center of $M\ddot{o}ssbauer$ spectrum represents the superparamagnetic phase of 12 % from ${\gamma}-Fe_2O_3$ phase.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4671-4677
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• 2023

For the first time Pb, Ni, and Cu nanocomposites were synthesized by versatile solution combustion synthesis using Aloevera extract as a reducing agent, to study the potential applications in X-ray/gamma, neutron, and Bremsstrahlung shielding. The synthesized Lead-Nickel-Copper (LNC) nanocomposites were characterized by PXRD, SEM, UV-VIS, and FTIR for the confirmation of successful synthesis. PXRD analysis confirmed the formation of multiphase LNC NCs and the Scherrer equation and the W-H plot gave the average crystal sizes of 19 nm and 17 nm. Surface morphology using SEM and EDX confirmed the presence of LNC NCs. Strong absorption peaks were analyzed by UV visible spectroscopy and the direct energy gap is found to be 3.083 eV. Functional groups present in the LNC NCs were analyzed by FTIR spectroscopy. X-ray/gamma radiation shielding properties were measured using NaI(Tl) detector coupled with MCA. It is found to be very close to Pb. Neutron shielding parameters were compared with traditional shielding materials and found LNC NCs are better than lead and concrete. Secondary radiation shielding known as Bremsstrahlung shielding characteristics also studied and found that LNC NCs are best in secondary radiation shielding. Hence LNC NCs find shielding applications in ionizing radiation such as X-ray/gamma and neutron radiation.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.812-818
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• 2011

[ $V_{0.9}Sb_{0.1}O_x$ ]systems, bulk and deposited on different supports (five types of ${\gamma}$-aluminas, ${\alpha}$-alumina, silica-alumina, silica gel, magnesium oxide), have been tested in the oxidative dehydrogenation (ODH) of iso-butane. This statement is derived from the data obtained by a set of characterisation techniques(specific surface area measurements, X-ray diffraction, X-ray photoelectron spectroscopy, laser Raman spectroscopy, in situ differential scanning calorimetry and in situ diffuse reflectance-absorption infrared Fourier transform spectroscopy).

• Journal of Powder Materials
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• v.9 no.5
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• pp.341-345
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• 2002

Nanoparticles of $Fe_2O_3$ with a mean particle size of 4-30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mossbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mossbauer spectrum, the amounts of $\gamma-Fe_2O_3$ and $\alpha-Fe_2O_3$ in as-prepared sample are about 70% and 30%, respectively. The coercivity (53 Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk $\gamma-Fe_2O_3$. The low value of coercivity and saturation magnetization indicate that the $\gamma-Fe_2O_3$ phase nearly shows the spin glass-like behavior. Analysis of the set of Mossbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk $\gamma-Fe_2O_3$ and $alpha-Fe_2O_3$. A quadrupole line on the center of spectrum represents of superparamagnetic phase of $\gamma-Fe_2O_3$ with a mean particle size of 7 nm or below.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.251-255
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• 2012

Pulp is typically used for paper industry to manufacturing various types of papers. However simply chemical modification makes enable the pulp to a wide range of application in various industrial fields. To bring the polymerization the gamma ray irradiated on the mixture of kenaf and PEGMA in various dose ranges from 20 to 60 kGy. As a results, the graft degree of 20.0% was obtained from 475 g of gamma ray irradiated pulp and PEGMA. After the polymerization, the chemical structure and morphology of the surfaces were examined by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscope. Chemical structure of grafted pulp has significantly growth in carbonyl content with increasing the radiation dose. Also surface morphology was distinctly changed with decreased the degree of roughness and increasing the diameter. These results were explained gamma ray irradiation improve performance of graft polymerization efficiency.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.01a
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• pp.15-15
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• 2002

• Journal of the Korean Vacuum Society
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• v.11 no.3
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• pp.171-175
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• 2002

The change in work function was studied on Indium-Tin-Oxide(ITO) surface after O-plasma treatment using $\gamma$-Focused ion Beam($\gamma$-FIB). As the surface of ITO experienced more O-plasma treatment, both the surface resistivity and the work function got higher. Auger Electron Spectroscopy identified the increase of oxygen as well as the decrease of Sn. The rise of work function and surface resistivity is considered to be due to the change in oxygen and Sn on the surface of ITO.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.135.1-135
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• 2003

To elucidate the effect of gamma-irradiation on the molecular properties of hemoglobin, the secondary, tertiary structure, and the molecular weight size of the protein were examined after irradiation at 0.5, 1, 5, and 10 kGy. Gamma-irradiation of hemoglobin solutions caused the disruption of the ordered structure of the protein molecules, as well as degradation, cross-linking, and aggregation of the polypeptide chains. A SDS-PAGE study indicated that irradiation caused initial fragmentation of the proteins and subsequent aggregation due to cross-linking of the protein molecules. The effect of irradiation on the protein was more significant at lower protein concentrations. Ascorbic acid decreased the degradation and aggregation of proteins by scavenging oxygen radicals that were produced by irradiation. A circular dichroism study showed that irradiation decreased the helical content of hemoglobin with a concurrent increase of the aperiodic structure content. Fluorescence spectroscopy indicated that irradiation decreased the emission intensity that was excited at 280 nm.

• Journal of Radiation Protection and Research
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• v.47 no.4
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• pp.214-225
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• 2022

Background: The conventional cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)) scintillator-based gamma-ray imager has a bulky detector, which can lead to incorrect positioning of the gammaray source if the shielding against background radiation is not appropriately designed. In addition, portability is important in complex environments such as inside nuclear power plants, yet existing gamma-ray imager based on a tungsten mask tends to be weighty and therefore difficult to handle. Motivated by the need to develop a system that is not sensitive to background radiation and is portable, we changed the material of the scintillator and the coded aperture. Materials and Methods: The existing GAGG(Ce) was replaced with Bi₄Ge₃O₁₂ (BGO), a scintillator with high gamma-ray detection efficiency but low energy resolution, and replaced the tungsten (W) used in the existing coded aperture with lead (Pb). Each BGO scintillator is pixelated with 144 elements (12 × 12), and each pixel has an area of 4 mm × 4 mm and the scintillator thickness ranges from 5 to 20 mm (5, 10, and 20 mm). A coded aperture consisting of Pb with a thickness of 20 mm was applied to the BGO scintillators of all thicknesses. Results and Discussion: Spectroscopic characterization, imaging performance, and image quality evaluation revealed the 10 mm-thick BGO scintillators enabled the portable gamma-ray imager to deliver optimal performance. Although its performance is slightly inferior to that of existing GAGG(Ce)-based gamma-ray imager, the results confirmed that the manufacturing cost and the system's overall weight can be reduced. Conclusion: Despite the spectral characteristics, imaging system performance, and image quality is slightly lower than that of GAGG(Ce), the results show that BGO scintillators are preferable for gamma-ray imaging systems in terms of cost and ease of deployment, and the proposed design is well worth applying to systems intended for use in areas that do not require high precision.