• Title/Summary/Keyword: $In_2O_3$ nanoparticles

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Magnetic Property of α-Fe2O3 Nanoparticles Prepared by Sonochemistry and Take-off Technique

  • Koo, Y.S.;Yun, B.K.;Jung, J.H.
    • Journal of Magnetics
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    • v.15 no.1
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    • pp.21-24
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    • 2010
  • A new synthetic method for the formation of uniform $\alpha-Fe_2O_3$ nanoparticles was reported and their magnetic properties were investigated. The sonochemical synthesis and the subsequent take-off technique resulted in spherical shaped $\alpha-Fe_2O_3$ nanoparticles with an average diameter of 60 nm. The temperature- and applied magnetic field-dependent magnetization of the $\alpha-Fe_2O_3$ nanoparticles was explained by the sum of two contributions, i.e., the Morin transition and superparamagnetism, because the critical size for superparamagnetism was within the size variation of the nanoparticles.

Synthesis of ZnO nanoparticles and their photocatalytic activity under UV light

  • Nam, Sang-Hun;Kim, Myeong-Hwa;Bu, Jin-Hyo
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.423-423
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    • 2011
  • Zinc oxide is metal oxide semiconductor with the 3.37 eV bandgap energy. Zinc oxide is very attractive materials for many application fields. Zinc Oxide has many advantages such as high conductivity and good transmittance in visible region. Also it is cheaper than other semiconductor materials such as indium tin oxide (ITO). Therefore, ZnO is alternative material for ITO. ZnO is attracting attention for its application to transparent conductive oxide (TCO) films, surface acoustic wave (SAW), films bulk acoustic resonator (FBAR), piezoelectric materials, gas-sensing, solar cells and photocatalyst. In this study, we synthesized ZnO nanoparticles and defined their physical and chemical properties. Also we studied about the application of ZnO nanoparticles as a photocatalyst and try to find a enhancement photocatalytic activity of ZnO nanorticles.. We synthesized ZnO nanoparticles using spray-pyrolysis method and defined the physical and optical properties of ZnO nanoparticles in experiment I. When the ZnO are exposed to UV light, reduction and oxidation (REDOX) reaction will occur on the ZnO surface and generate O2- and OH radicals. These powerful oxidizing agents are proven to be effective in decomposition of the harmful organic materials and convert them into CO2 and H2O. Therefore, we investigated that the photocatalytic activity was increased through the surface modification of synthesized ZnO nanoparticles. In experiment II, we studied on the stability of ZnO nanoparticles in water. It is well known that ZnO is unstable in water in comparison with TiO2. Zn(OH)2 was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoparticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their photocatalytic activity changes.

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Synthesis of TiO2 nanoparticles induced by electron beam irradiation and their electrochemical performance as anode materials for Li-ion batteries

  • Ahn, Ja-Hwa;Eom, Ji-Yong;Kim, Jong-Huy;Kim, Hye Won;Lee, Byung Cheol;Kim, Sung-Soo
    • Journal of Electrochemical Science and Technology
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    • v.6 no.3
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    • pp.75-80
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    • 2015
  • We introduce a new synthesis method to prepare small TiO2 nanoparticles with a narrow particle size distribution, which is achieved by electron beam (E-beam) irradiation. The effects of E-beam irradiation on the synthesis of TiO2 nanoparticles and the electrochemical performance of TiO2 nanoparticles as alternative anode materials for Li-ion batteries are investigated. The TiO2 nanoparticles induced by E-beam irradiation present better cycling performance and rate capability than the TiO2 nanoparticles synthesized by normal hydrolysis reaction. The better electrochemical performance is attributed to small particle size and narrow particle size distribution, resulting in the large surface area that provides innumerable reaction sites and short diffusion length for Li+ through TiO2 nanoparticles.

Cryogenic microwave dielectric properties of Mg2TiO4 ceramics added with CeO2 nanoparticles

  • Bhuyan, Ranjan K.;Thatikonda, Santhosh K.;Dobbidi, Pamu;Renehan, J.M.;Jacob, Mohan V.
    • Advances in materials Research
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    • v.3 no.2
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    • pp.105-116
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    • 2014
  • The microwave dielectric properties of $CeO_2$ nanoparticles (0.5, 1.0 & 1.5wt%) doped $Mg_2TiO_4$ (MTO) ceramics have been investigated at cryogenic temperatures. The XRD patterns of the samples were refined using the full proof program reveal the inverse spinel structure without any secondary phases. The addition of $CeO_2$ nanoparticles lowered the sintering temperature with enhancement in density and grain size as compared to pure MTO ceramics. This is attributed to the higher sintering velocity of the fine particles. Further, the microwave dielectric properties of the MTO ceramics were measured at cryogenic temperatures in the temperature range of 6.5-295 K. It is observed that the loss tangent ($tan{\delta}$) of all the samples increased with temperature. However, the $CeO_2$ nanoparticles doped MTO ceramics manifested lower loss tangents as compared to the pure MTO ceramics. The loss tangents of the pure and MTO ceramics doped with 1.5 wt% of $CeO_2$ nanoparticles measured at 6.5K are found to be $6.6{\times}10^{-5}$ and $5.4{\times}10^{-5}$, respectively. The addition of $CeO_2$ nanoparticles did not cause any changes on the temperature stability of the MTO ceramics at cryogenic temperatures. On the other hand, the temperature coefficient of the permittivity increased with rise in temperature and with the wt% of $CeO_2$ nanoparticles. The obtained lower loss tangent values at cryogenic temperatures can be attributed to the decrease in both intrinsic and extrinsic losses in the MTO ceramics.

Electrochemical Characteristics of Indium Tin Oxide Nanoparticles prepared by Sol-gel Combustion Hybrid Method

  • Chaoumead, Accarat;Choi, Woo-Jin;Lee, Dong-Hoon;Sung, Youl-Moon
    • Journal of Electrical Engineering and Technology
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    • v.6 no.3
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    • pp.414-417
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    • 2011
  • Indium tin oxide (In:$SnO_2$) nanoparticles were synthesized employing a sol-gel combustion method followed by annealing. The TG, XRD, XPS and SEM results of the precursor powders and calcinated In:$SnO_2$ nanoparticles were investigated. Crystal structures were examined by powder XRD, and those results show shaper intensity peak at $25.6^{\circ}$ ($2{\theta}$) of $SnO_2$ by increased annealing temperature. A particle morphology and size was examined by SEM, and the size of the nanoparticles was found to be in the range of 20~30nm. In:$SnO_2$ films could controlled by nanoparticle material at various annealing temperature. The sol-gel combustion method was offered simple and effective route for the synthesis of In:$SnO_2$ nanoparticles.

Synthesis of $\beta$-$Ga_2$$O_3 Nanobelts and Nanoparticles from Mechanically Ground GaN Powders with Different Thermal Annealing Atmospheres (기계적으로 연마한 GaN 분말로부터 열처리 분위기를 달리한 $\beta$-$Ga_2$$O_3 나노벨트 및 나노입자의 합성)

  • Kim, Byung-Cheul;Sun, Kyu-Tae;Park, Kwang-Soo;Im, Ki-Joo;Noh, Tae-Yong;Nahm, Sahn;Sung, Man-Young;Kim, Sang-Sig
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.12
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    • pp.965-971
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    • 2001
  • $\beta$-Ga$_2$O$_3$ nanobelts and nanoparticles were synthesized from mechanically ground GaN powders with thermal annealing in a nitrogen atmosphere and an oxygen atmosphere, respectively. The study of field emission scanning electron microscopy (FESEM) on the microstructures of nanomaterials revealed that the nanobelts synthesized in the nitrogen atmosphere are with the range of 20~1000nm width and 10 ~100nm thickness, and that nanomaterials are nanoparticles with 20~50nm radius obtained by thermal annealing in an oxygen atmosphere. The crystal structure of the $\beta$-Ga$_2$O$_3$ nanobelts and nanoparticles was in this study investigated by X-ray diffractometer (XRD) and high-resolution transmission electron microscope (HRTEM). The formation processes of the nanobelts and nanoparticles will be discussed in this paper.

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A highly effective route for removal of Hg2+ from the waste water using 3-nitrobenzelidenemalononitrile as a modifier of Fe3O4@SiO2 nanoparticles

  • Mosleh Mehryar;Ghasem Marandi
    • Advances in nano research
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    • v.16 no.1
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    • pp.1-9
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    • 2024
  • SiO2-coated magnetic nanoparticles (Fe3O4@SiO2 NPs) were modified by 3-nitrobenzelidenmalononitrile and used as green linkages for removal of Hg2+ form the wastewater. In this research, it has been attempted to refer to the harmful effects of mercury ions for living things and how to remove such ions using very easy and practical technique. This study shows that by optimizing the test conditions, the efficiency of the removal of harmful ions such as mercury from the water contaminated with these ions can be increased. Conditions such as temperature, speed of agitation, pH of solution were tested for removal of mercury ions. The advantages of this method over other methods listed in the article are the rapid and easy nanocry synthesis. The generated and modified Fe3O4@SiO2 nanoparticles were characterized by X-ray diffraction, fourier transform infrared and scanning electron microscopy spectroscopy. The results show that the synthesized magnetic nanoparticles have the excellent performance for the removal of mercury(II) ion from the waste water.

Fluid Flow and Convective Heat Transfer Characteristics of Al2O3 Nanofluids (알루미나 나노유체의 유동 및 대류 열전달 특성)

  • Hwang, Kyo-Sik;Lee, Ji-Hwan;Lee, Byeong-Ho;Jang, Seok-Pil
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.1 s.256
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    • pp.16-20
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    • 2007
  • In this paper, convective heat transfer and flow characteristics of $Al_2O_3$ nanoparticles suspended in water flowing through uniformly heated tubes are experimentally investigated under laminar flow regime. The heat transfer coefficient and the pressure drop of nanoparticles suspended in water are experimentally presented according to the pumping power. In addition, the heat transfer coefficient and the pressure drop of $Al_2O_3$ nanoparticles suspended in water are compared with those of pure water under the fixed pumping power. It is shown that the heat transfer coefficient of $Al_2O_3$ nanofluids with 0.1% volume fraction is enhanced by about 12% although the increment of the pressure drop of those is 4% compared with those of pure water.

Toxicity evaluation based on particle size, contact angle and zeta potential of SiO2 and Al2O3 on the growth of green algae

  • Karunakaran, Gopalu;Suriyaprabha, Rangaraj;Rajendran, Venkatachalam;Kannan, Narayanasamy
    • Advances in nano research
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    • v.3 no.4
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    • pp.243-255
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    • 2015
  • In this investigation, ecotoxicity of nano and micro metal oxides, namely silica ($SiO_2$) and alumina ($Al_2O_3$), on the growth of green algae (Porphyridium aerugineum Geitler) is discussed. Effects of nano and micro particles on the growth, chlorophyll content and protein content of algae are analysed using standard protocols. Results indicate that $SiO_2$ nano and micro $SiO_2$ particles are non-toxic to P. aerugineum Geitler up to a concentration of 1000 mg/L. In addition, $Al_2O_3$ microparticles are less toxic to P. aerugineum Geitler, whereas $Al_2O_3$ nanoparticles are found to be highly toxic at 1000 mg/L. Moreover, $Al_2O_3$ nanoparticles decrease the growth, chlorophyll content, and protein content of tested algae. In addition, zeta potential and contact angle are also important in enhancing the toxicity of metal oxide nanoparticles in aquatic environment. This study highlights a new insight into toxicity evaluation of nanoparticles on beneficial aquatic organisms such as algae.

Vibration analysis of silica nanoparticles-reinforced concrete beams considering agglomeration effects

  • Shokravi, Maryam
    • Computers and Concrete
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    • v.19 no.3
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    • pp.333-338
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    • 2017
  • In this paper, nonlinear vibration of embedded nanocomposite concrete is investigated based on Timoshenko beam model. The beam is reinforced by with agglomerated silicon dioxide (SiO2) nanoparticles. Mori-Tanaka model is used for considering agglomeration effects and calculating the equivalent characteristics of the structure. The surrounding foundation is simulated with Pasternak medium. Energy method and Hamilton's principal are used for deriving the motion equations. Differential quadrature method (DQM) is applied in order to obtain the frequency of structure. The effects of different parameters such as volume percent of SiO2 nanoparticles, nanoparticles agglomeration, elastic medium, boundary conditions and geometrical parameters of beam are shown on the frequency of system. Numerical results indicate that with increasing the SiO2 nanoparticles, the frequency of structure increases. In addition, considering agglomeration effects leads to decrease in frequency of system.