• Advances in nano research
• /
• 제3권3호
• /
• pp.169-176
• /
• 2015

Iron nanoparticles were made by using the modified coprecipitation technique. Usually the characteristics of synthesised particles depend upon the process parameters such as the ratio of the iron ions, the pH of the solution, the molar concentration of base used, type of reactants and temperature. A modified coprecipitation method was adopted in this study. A magnetic stirrer was used for mixing and the morphology and nature of particles were observed after synthesis. Nanoparticles were characterised through XRD. Obtained nanoparticles showed the formation of magnetite and maghemite under citric acid and oxalic acid as stabilisers respectively. The size of nanoparticle was greatly affected by the use of different types of stabilisers. Results show that citric acid greatly reduced the obtained particle size. Particle size as small as 13 nm was obtained in this study. The effects of different kinds of nucleating agents were also observed and two different types of nucleating agents were used i.e. potassium hydroxide (KOH) and copper chloride ($CuCl_2$). Results show that the use of nucleating agent in general pushes the growth phase of nanoparticles towards the end of coprecipitation reaction. The particles obtained after addition of nucleating agent were greater in size than particles obtained by not utilising any nucleating agent. These particles have found widespread use in medical sciences, energy conservation and electronic sensing technology.

• 한국자기학회지
• /
• 제5권5호
• /
• pp.745-748
• /
• 1995

Magnetic nanoparticles of iron and iron oxide have been prepared in a modified upward thermal diffusion cloud chamber using pulsed laser evaporation. SEM/TEM studies of these particles reveal a size distribution with a mean diameter of about $60\;{\AA}$. FTIR spectrum measurements are used to investigate the difference in oxidation level between nanoparticles prepared at different partial oxygen pressures. The complex magnetic behaviour of these particles was studied using DC- and AC-susceptibility measurements. All samples exhibit superparamagnetism with blocking temperatures ranging from 50 K to above room temperature. The coercivity fields as well as the dependence of the blocking temperature on measuring frequency have been studied. magnetic anisotropy constants are found to be one order of magnitude higher than is known for the bulk values. The mean particle size estimated from the magnetic data is found to be in perfect agreement with the TEM observations.

• Journal of Magnetics
• /
• 제21권2호
• /
• pp.179-182
• /
• 2016

In this paper, 10 nm $Fe_3O_4$ nanoparticles were modified on the surface of $2{\mu}m$ flower-like bismuth oxychloride (BiOCl) spheres by a facile co-precipitation method. The results showed that the $Fe_3O_4/BiOCl$ nanocomposites exhibited excellent photocatalytic activity and superparamagnetic property ($M_s=3.22emu/g$) under visible light for Rhodamine B (RhB) degradation. Moreover, the $Fe_3O_4-BiOCl$ photocatalyst possessed magnetic recyclable property, which could maintain high photocatalytic effective even after 20 cycle times. These characteristic indicates a promising application for wastewater treatment.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.260-260
• /
• 2006

Sericin was modified by solution blending (10-30 wt%) with 70-90 wt% polyacrylamide (PAM) in water. The reactive sites of sericin such as serine and tyrosine were attached to PAM. Proton Nuclear Magnetic Resonance ($^{1}H-NMR$) and thermogravimetric analysis were used to characterize the modified sericin. The electrospinning conditions i.e. the blend composition and the power supply voltage, at a tip to target distance of 15 cm were studied. The morphology of nanoparticles and nanofibers was observed by scanning electron microscopy. The average particles size of the nanoparticle obtained was 191 nm and nanofibers was 150-300 nm.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2008년도 Asian Magnetics Conference
• /
• pp.255.2-255.2
• /
• 2008

• 한국재료학회지
• /
• 제22권6호
• /
• pp.275-279
• /
• 2012

(3-mercaptopropyl)trimethoxysilane (MPTMS) was used as a silylation agent, and modified silica nanoparticles were prepared by solution polymerization. 2.0 g of silica nanoparticles, 150 ml of toluene, and 20 ml of MPTMS were put into a 300 ml flask, and these mixtures were dispersed with ultrasonic vibration for 60 min. 0.2 g of hydroquinone as an inhibitor and 1 to 2 drops of 2,6-dimethylpyridine as a catalyst were added into the mixture. The mixture was then stirred with a magnetic stirrer for 8 hrs. at room temperature. After the reaction, the mixture was centrifuged for 1 hr. at 6000rpm. After precipitation, 150 ml of ethanol was added, and ultrasonic vibration was applied for 30 min. After the ultrasonic vibration, centrifugation was carried out again for 1 hr. at 6000rpm. Organo-modification of silica nanoparticles with a ${\gamma}$-methacryloxypropyl functional group was successfully achieved by solution polymerization in the ethanol solution. The characteristics of the ${\gamma}$-mercaptopropyl modified silica nanoparticles (MPSN) were examined using X-ray photoelectron spectroscopy (XPS, THERMO VG SCIENTIFIC, MultiLab 2000), a laser scattering system (LSS, TOPCON Co., GLS-1000), Fourier transform infrared spectroscopy (FTIR, JASCO INTERNATIONL CO., FT/IR-4200), scanning electron microscopy (SEM, HITACHI, S-2400), an elemental analysis (EA, Elementar, Vario macro/micro) and a thermogravimetric analysis (TGA, Perkin Elmer, TGA 7, Pyris 1). From the analysis results, the content of the methacryloxypropyl group was 0.98 mmol/g and the conversion rate of acrylamide monomer was 93%. SEM analysis results showed that the organo-modification of ultra-fine particles effectively prevented their agglomeration and improved their dispensability.

• 한국연소학회지
• /
• 제16권2호
• /
• pp.33-39
• /
• 2011

We demonstrated heat generation efficiency of the magnetic hyperthermia system to find optimal condition using gelatin tissue phantom. Magnetic hyperthermia induction can be used to make heat generation with different concentration of $Fe_3O_4$ iron oxide inside tissue phantom and magnetically labeled cells by applying AC magntic field at a frequency of 145 kHz. It was observed that the maximum temperature achieved in the magnetic gelatin tissue phantom increased with the concentration of $Fe_3O_4$ iron oxide and alternating magnetic field intensity. Results were discussed with respect to further optimization of therapeutic technique for biomedical application with modified functional nanoparticles.

• 한국초전도ㆍ저온공학회논문지
• /
• 제12권3호
• /
• pp.7-11
• /
• 2010

For many large-scale applications of high-temperature superconducting materials, large critical current density($J_c$) in high applied magnetic fields are required. A number of methods have been reported to introduce artificial pinning centers(APCs) in $YBa_2Cu_3O_{7-\delta}$(YBCO) films for enhancement of their $J_c$. In this work, we investigated electric characteristic of YBCO films on $SrTiO_3$ (100) substrates whose surfaces were modified by the introduction of Au nanoparticles (AuNPs). Au nanoparticles were uniformly dispersed on STO substrates with one of typical solution techniques, self assembled monolayer. After heating the STO substrates with Au nanoparticles, the size of Au nanoparticles was around 29~32 nm in height and 41~49 nm in diameter. XRD diffraction patterns taken on the YBCO film with Au nanoparticles show the c-axis orientation. The measured $T_c$ of YBCO /AuNPs films was around 89K and the $J_c$ was 0.75 MA/$cm^2$ at 65 K and 1 T.

• Korean Chemical Engineering Research
• /
• 제54권5호
• /
• pp.636-647
• /
• 2016

Magnetite nanoparticles ($Fe_3O_4$ NPs) were synthesized by co-precipitating method under optimized condition. The $Fe_3O_4$ NPs coated with sodium dodecyl sulfate-thenoyltrifluoroacetone ($Fe_3O_4$ NPs-SDS-TTFA) were then exerted as the magnetic solid phase extraction (MSPE) adsorbent for the extraction process prior to introducing to a flame atomic adsorption spectrometry (FAAS). The synthesized $Fe_3O_4$ NPs-SDS-TTFA were applied for the extraction of Pb(II) ions from different water samples. The characterization studies of nanoparticles were performed via scanning electron microscopy-energy dispersive micro-analysis (SEM-EDAX), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) techniques. The substantial parameters affecting the extraction efficiency were surveyed and optimized. A dynamic linear range (DLR) of $10-400{\mu}g\;L^{-1}$ was obtained and the limit of detection (LOD, n=7) and relative standard deviation (RSD%, n= 6, $C=20{\mu}g\;L^{-1}$) were found to be $2.3{\mu}g\;L^{-1}$ and 1.9%, respectively. According to the results, the proposed method successfully applied for the extraction of Pb(II) ions from different environmental water samples and satisfactory results achieved.

• Nano
• /
• 제13권11호
• /
• pp.1850128.1-1850128.10
• /
• 2018

Glutathione (GSH), the protective agent and reducing agent, has been widely used to prepare gold nanoclusters (GSH-Au NCs) with stable fluorescence properties and negative charge of the surface. Meanwhile, polyethyleneimine (PEI) was used as the modification agent to synthesize magnetic ferroferric oxide nanoparticles ($Fe_3O_4$) with fantastic dispersibility and positive charge of the surface. Based on the electrostatic adsorption force, magnetic nano-$Fe_3O_4@GSH-Au$ NCs core-shell microspheres composed of magnetic $Fe_3O_4$ nanoparticles modified by PEI as the core and GSH-Au NCs as the shell were assembled. The prepared $Fe_3O_4@GSH-Au$ NCs microspheres harbored a uniform size (88.6 nm), high magnetization (29.2 emu/g) and excellent fluorescence. Due to the coordination bond action between Au atom and sulfhydryl (-SH), amino ($-NH_2$), carboxyl (-COOH) in sweat, $Fe_3O_4@GSH-Au$ NCs could combine with latent fingerprints. In addition, $Fe_3O_4@GSH-Au$ NCs with good fluorescence and magnetism could detect fingerprints on various objects. Significantly, the powders were not easy to suspend in the air, which avoided the damage to the health of forensic experts and the fingerprints by only powder contacting. Above all, $Fe_3O_4@GSH-Au$ NCs was successfully applied to the latent fingerprint visualization, which has great potential in forensic science.