• Journal of Magnetics
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• 제11권3호
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• pp.123-125
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• 2006

Co-ferrite nanoparticles have been synthesized by the decomposition of iron(III) acetylacetonate, $Fe(acac)_3$ and Co acetylacetonate, $Co(acac)_2$ in benzyl/phenyl ether in the presence of oleic acid and oleyl amine at the refluxing temperature of $295^{\circ}C$/$265^{\circ}C$ for 30 min. before cooling to room temperature. Particle diameter detected by PSA can be turned from 4 nm to 20 nm by seed-mediated growth and reaction conditions. Structural and magnetic characterization of Co-ferrite were measured by use of HRTEM, SAED (selected area electron diffraction), XRD and SQUID. The as-synthesized Co-ferrite nanoparticles have a cubic spinel structure and coercivity of 20 nm $CoFe_{2}O_{4} nanoparticles reached 1 kOe at room temperature and 18 kOe at 10 K.

• Journal of Magnetics
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• 제20권3호
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• pp.207-210
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• 2015

Modifications in the structural and magnetic properties of co-precipitated cobalt ferrite nanoparticles can be accomplished by varying the annealing time periods during the synthetic process. Experimental results show that high-purity cobalt ferrite nanoparticles are obtained using a co-precipitation process. The dependence of the crystallite sizes on the annealing time was successfully demonstrated using XRD and SEM. Finally, vibrating sample magnetometer analyses show that the magnetic properties of the cobalt ferrite nanoparticles depend on their relative particle sizes.

• Journal of Magnetics
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• 제22권2호
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• pp.169-174
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• 2017

In this work, lithium ferrite ($Li_{0.5}Fe_{2.5}O_4$) nanoparticles were prepared via mechanochemical processing and subsequent heat treatment at a relatively low ($600^{\circ}C$) calcining temperature. The raw materials used were high purity $Fe_2O_3$ and $Li_2CO_3$ that were milled for between 2 and 20 h. The milled powders were then calcined at temperatures of 500 and $600^{\circ}C$ for 5 h in air. XRD results show that optimum conditions to obtain single phase lithium ferrite nanoparticles with a mean crystallite size of about 23 nm, using Scherrer's formula, are 10 h milling and calcination at $600^{\circ}C$. Saturation magnetization and coercivity of the single phase Li ferrite nanoparticles are 44.6 emu/g and 100 Oe respectively, which are both smaller than those of the bulk Li ferrite. The Curie temperature of the single sample was determined by a Faraday balance, which is $578^{\circ}C$ and smaller than that of bulk Li ferrite.

• Journal of Magnetics
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• 제11권3호
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• pp.115-118
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• 2006

Co-ferrite nanoparticles have been synthesized by the decomposition of iron(III) acetylacetonate, $Fe(acac)_3$ and Co acetylacetonate, $Co(acac)_2$ in benzyl/phenyl ether in the presence of oleic acid and oleyl amine at the refluxingtemperature of $295^{\circ}C$/$265^{\circ}C$ for 30 min. before cooling to room temperature. Particle diameter detected by PSA can be turned from 4 nm to 20 nm by seed-mediated growth and reaction conditions. Structural and magneticcharacterization of Co-ferrite were measured by use of HRTEM, SAED (selected area electron diffraction), XRD and SQUID. The as-synthesized Co-ferrite nanoparticles have a cubic spinel structure and coercivity of 20 nm $CoFe_{2}O_{4} nanoparticles reached 1 kOe at room temperature and 18 kOe at 10 K.

• Advances in nano research
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• 제13권5호
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• pp.437-451
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• 2022

Synthesis approaches usually affect the physical and chemical properties of ferrites. This helps ferrite materials to design them for desired applications. Some of these methods are mechanical milling, ultrasonic method, micro-emulsion, co-precipitation, thermal decomposition, hydrothermal, microwave-assisted, sol-gel, etc. These methods are extensively reviewed by taking example of ZnFe₂O₄. These methods also affect the microstructure and local structure of ferrite which ultimately affect the physical and chemical properties of ferrites. Various spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Ultra Violet-Visible spectroscopy, Mossbauer spectroscopy, extended x-ray absorption fine structure, and electron paramagnetic resonance are found helpful to reveal this information. Hence, the basic principle and the usefulness of these techniques to find out appropriate information in ZnFe₂O₄ nanoparticles is elaborated in this review.

• 한국세라믹학회지
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• 제46권1호
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• pp.69-73
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• 2009

We report the preparation of nanocrystalline cobalt ferrite, $CoFe_2O_4$ particles and their surface coating with silica layers using micro emulsion method. The cobalt ferrite nanoparticles with the size 7nm are firstly prepared by thermal decomposition method. Hydrophobic nanoparticles were coated with silica using micro-emulsion method with surfactant, $NH_4OH$, and tetraethylorthosilicate (TEOS). Monodispersed and spherical silica coated cobalt ferrite nanoparticles have average particle diameter of 38 nm and narrow sized distribution.

• Advances in nano research
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• 제3권2호
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• pp.111-121
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• 2015

$CoFe_2O_4$ nanotubes and porous nanorods were prepared via a simple one-pot template-free hydrothermal method and were used as an adsorbent for the removal of dye contaminants from water. The properties of the synthesized nanotubes and porous nanorods were characterized by electron diffraction, transmission electron microscopy and x-ray powder diffraction. The Adsorption characteristics of the $CoFe_2O_4$ were examined using polar red dye and the factors affecting adsorption, such as, initial dye concentration, pH and contact time were evaluated. The overall trend followed an increase of the sorption capacity reaching a maximum of 95% dye removal at low pHs of 2-4. An enhancement in the removal efficiency was also noticed upon increasing the contact time between dye molecules and $CoFe_2O_4$ nanoparticles. The final results indicated that the $CoFe_2O_4$ nanotubes and porous nanorods can be considered as an efficient low cost and recyclable adsorbent for dye removal with efficiency 94% for Cobalt ferrite nanotubes and for Cobalt ferrite porous nanorods equals 95%.

• Advances in nano research
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• 제4권1호
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• pp.1-14
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• 2016

Superparamagnetic iron oxide nanoparticles (Nps), composed of magnetite, $Fe_3O_4$, or maghemite, ${\gamma}-Fe_2O_3$, core and biocompatible polymer shell, such as dextran or chitozan, have recently found wide applications in magnetic resonance imaging, contrast enhancement and hyperthermia therapy. For different diagnostic and therapeutic applications, current attempt is focusing on the synthesis and biomedical applications of various ferrite Nps, such as $CoFe_2O_4$ and $MnFe_2O_4$, differing from iron oxide Nps in charge, surface chemistry and magnetic properties. This study is focused on the synthesis of manganese ferrite, $MnFe_2O_4$, Nps by most commonly used chemical way pursuing better control of their size, purity and magnetic properties. Co-precipitation syntheses were performed using aqueous alkaline solutions of Mn(II) and Fe(III) salts and NaOH within a wide pH range using various hydrothermal treatment regimes. Different additives, such as citric acid, cysteine, glicine, polyetylene glycol, triethanolamine, chitosan, etc., were tested on purpose to obtain good yield of pure phase and monodispersed Nps with average size of ${\leq}20nm$. Transmission electron microscopy (TEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), $M\ddot{o}ssbauer$ spectroscopy down to cryogenic temperatures, magnetic measurements and inductively coupled plasma mass spectrometry were employed in this study.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.217.1-217.1
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• 2007

• 한국자기학회지
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• 제18권3호
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• pp.120-125
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• 2008

여러 가지 다른 조성의 NiCoZn ferrite를 공침법으로 제조한 후 소결온도를 변화시켜 NiCoZn ferrite 미분말을 제조하였다. 제조된 미분말의 미세조직, 결정구조 및 전기적 특성을 분석하였고, 복합형 NiCoZn ferrite 전파흡수체를 제작하여 전파흡수 특성을 분석하였다. 합성한 미분말들은 전형적인 NiCoZn spinel 구조를 지니고 있음을 확인하였고, 입자 크기가 평균 40 nm의 나노분말을 가짐을 알 수 있었다. NiCoZn ferrite를 소결온도를 달리하여 제조한 결과, $1250^{\circ}C$에서 소결된 NiCoZn ferrite가 불순물이 적고 초투자율 및 Q 값이 가장 낮게 나왔다. 또한 S-parameter를 측정하여 반사 감쇠율을 계산한 결과 두께 2 mm인 $(Ni_{0.4}Co_{0.1}Zn_{0.5})Fe_2O_4$ 조성의 시트형 전파흡수체는 6 GHz의 주파수 대역에서 -3.1 dB의 반사 감쇠율을 보여주었다. 이런 측정 결과 6 GHz 이상의 고주파 영역에서 복합 ferrite 전파흡수체로서 응용이 가능할 것으로 사료된다.