IMPROVEMENT OF COERCIVITY IN COBALT-DOPED ANATASE TiO2 NANOPARTICLES HYDROTHERMALLY PREPARED

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2550-2555
Author(s):  
MINGZAI WU ◽  
YING XIONG ◽  
NAN JIANG ◽  
HAI PING QI ◽  
QIANWANG CHEN
Keyword(s):  
Room Temperature ◽  
Magnetic Measurement ◽  
Hydrothermal Process ◽  
Hysteresis Loops ◽  
Anatase Tio2 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Measurement Results ◽  
Ferromagnetic Hysteresis

Anatase Ti 1-x Co x O 2 nanoparticles were prepared by a hydrothermal process at 180 °C. Ferromagnetic hysteresis loops of the as-prepared samples were measured at room temperature. The Ti 1-x Co x O 2 ( x = 0.0376) powder shows coercivity up to 700 Oe, which is the highest value reported for anatase Ti 1-x Co x O 2. X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurement results provided evidence that Co was incorporated into TiO 2 lattice. Combined with the fact that the preparation was carried out in an oxidized environment starting from cobalt (II) in the oxidized state, it is suggested that the homogeneous doping of Co into the lattice of anatase should be responsible for the improvement of coercivity in anatase Ti 1-x Co x O 2 nanoparticles.

scholarly journals Influence of different synthesis conditions on properties of oleic acid-coated-Fe3O4 nanoparticles

2015 ◽  
Vol 33 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Atieh Aliakbari ◽  
Majid Seifi ◽  
Sharareh Mirzaee ◽  
Hoda Hekmatara
Keyword(s):  
Oleic Acid ◽  
Room Temperature ◽  
Magnetic Measurement ◽  
Precursor Solution ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Transmission Electron ◽  
Ft Ir

AbstractIn the present paper, iron oxide nanoparticles coated by oleic acid have been synthesized in different conditions by coprecipitation method. For investigating the effect of time spent on adding the oleic acid to the precursor solution, two different processes have been considered. The as synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Magnetic measurement was carried out at room temperature using a vibrating sample magnetometer (VSM). The results show that the magnetic nanoparticles decorated with oleic acid decreased the saturation of magnetization. From the data, it can also be concluded that the magnetization of Fe3O4/oleic acid nanoparticles depends on synthesis conditions.

CoNiP/Au Multisegment Magnetic Nanowires: Synthesis and Aminothiophenol (4-ATP) Functionalization

2017 ◽  
Vol 33 (2) ◽  
Author(s):  
Do Quang Ngoc ◽  
Hoang Thi Nu ◽  
Luu Van Thiem ◽  
Luu Manh Quynh ◽  
Le Tuan Tu
Keyword(s):  
Room Temperature ◽  
Hysteresis Loops ◽  
Magnetic Nanowires ◽  
Vibrating Sample Magnetometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Au Nanowires

Abstract: The magnetic properties in CoNiP/Au multisegments nanowire were investigated. All the samples were prepared by electrodeposition method with pH of 5.5 and room temperature. The electrochemical potential of CoNiP was determined by cycle voltammetary. The crystalline structure and morphology of the samples were characterized by X-ray diffraction (XRD), Scanning Electron Miroscopy (SEM) and High-resolution transmission electron microscopy (HRTEM), respectively. The hysteresis loops were measured at room temperature using vibrating sample magnetometry (VSM). The SEM and TEM image showed that the CoNiP/Au nanowires with diameters about 50 nm. The lattice spacing of the  CoNiP samples were 0.205 nm. The obtained results of VSM show that, the coercivity is 1006 Oe. The 4-Aminothiophenol (4-ATP) functionalized CoNiP/Au were combined by inverse emulsion method in order to apply to biomedicine.  The characteristic Surface Enhanced Raman peak positions of 4-ATP absorbed on the Au segments were occurred without any alterations, which significantly predicted attractive applicability of the colloids for biomedical labeling.  

Structure and Magnetic Properties of Carbon Encapsulated Co Nanoparticles Prepared by the Pyrolysis of Mixture of Sucrose and Cobalt Nitrate

2010 ◽  
Vol 97-101 ◽  
pp. 2201-2204
Author(s):  
Jun Xue ◽  
S.C. Chen ◽  
H.K. Tang ◽  
H.K. Xiang ◽  
X.H. Wang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Measurement ◽  
Ferromagnetic Material ◽  
Cobalt Nitrate ◽  
Nitrogen Atmosphere ◽  
Nanometer Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Nanoparticles

Carbon-encapsulated Cobalt nanoparticles were synthesized with sucrose as carbon source and cobalt nitrate as metal source in nitrogen atmosphere. The weight of purified sample could arrive around 12-20 grams at one time. The as-prepared CECNPs sample was characterized by transmission electron microscopy (TEM), X-ray diffraction technique (XRD), vibrating sample magnetometer (VSM) and Raman spectroscopy. The results showed CECNPs was typical core / shell structure on nanometer scale, the core was cobalt single crystal, the shell was graphitic carbon, and the particle size was about 30nm. The magnetic measurement revealed that CECNPs was ferromagnetic material with the quite small remanent magnetizations Mr of 3.7emu/g and coercive forces Hc of 275Oe at room temperature.

FABRICATION OF BaFe12O19 NANOWIRES BY A HYDROTHERMAL PROCESS AND THEIR MAGNETIC PROPERTIES

2006 ◽  
Vol 20 (07) ◽  
pp. 359-364 ◽  
Author(s):  
JUN WANG ◽  
YUEJIN ZHU
Keyword(s):  
Electron Microscopy ◽  
Saturation Magnetization ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Hydrothermal Process ◽  
Annealing Treatment ◽  
Magnetization Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Magnetic BaFe 12 O 19 nanowires have been prepared by a hydrothermal process. The nanowires with diameters ~ 15 nm and lengths ~ 2 μ m are clearly visible in Transmission Electron Microscopy (TEM) image. The physical properties of the BaFe 12 O 19 nanowires were further characterized by X-ray diffraction (XRD) and magnetization measurement. The results of the magnetization measurement show that the sample displays ferromagnetic properties at room temperature and its saturation magnetization (Ms) reaches 13.36 emu/g. Annealing treatment of the sample in air at 800°C leads to the increasing of the saturation magnetization (Ms: 65.7 emu/g). It is suggested that the oxygen vacancies should be responsible for the low saturation magnetization, which is also supported by the magnetic property (Ms: 21.6 emu/g) of the sample annealed at 800°C in argon shield.

scholarly journals Synthesis and Magnetic Properties of Hematite Particles in a “Nanomedusa” Morphology

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jin Bae Lee ◽  
Hae Jin Kim ◽  
Janez Lužnik ◽  
Andreja Jelen ◽  
Damir Pajić ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Hydrothermal Process ◽  
Ferromagnetic State ◽  
X Ray Diffraction ◽  
Morin Transition ◽  
Preferential Direction ◽  
X Ray ◽  
Transmission Electron

We present the synthesis, characterization, and magnetic properties of hematite particles in a peculiar “nanomedusa” morphology. The particles were prepared from an iron-silica complex by a hydrothermal process in a solution consisting of ethyl acetate and ethanol. The particles’ morphology, structure, and chemical composition were investigated by transmission electron microscopy, powder X-ray diffraction, and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The “hairy” particles consist of a spherical-like core of about 100 nm diameter and fibrous exterior composed of thin “legs” of 5 nm diameter grown along one preferential direction. The particles’ cores are crystalline and undergo a magnetic phase transition to a weakly ferromagnetic state at a temperature of 930 K that matches reasonably the Néel temperature of bulk hematite. However, unlike bulk hematite that undergoes Morin transition to an antiferromagnetic state around room temperature and small hematite nanoparticles that are superparamagnetic, the “nanomedusa” particles remain weakly ferromagnetic down to the lowest investigated temperature of 2 K. Each particle thus represents a nanodimensional “hairy” ferromagnet in a very broad temperature interval, extending much above the room temperature. Such high-temperature ferromagnetic nanoparticles are not frequently found among the nanomaterials.

Photoluminescence Enhancement of CdS Nanocrystals Fabricated on Dithiocarbamate Functionalized PET Substrates

2012 ◽  
Vol 512-515 ◽  
pp. 1511-1515
Author(s):  
Chun Lin Zhao ◽  
Li Xing ◽  
Xiao Hong Liang ◽  
Jun Hui Xiang ◽  
Fu Shi Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Hexagonal Structure ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Cds Nanocrystals ◽  
Morphological Studies ◽  
Transmission Electron

Cadmium sulfide (CdS) nanocrystals (NCs) were self-assembled and in-situ immobilized on the dithiocarbamate (DTCs)-functionalized polyethylene glycol terephthalate (PET) substrates between the organic (carbon disulfide diffused in n-hexane) –aqueous (ethylenediamine and Cd2+ dissolved in water) interface at room temperature. Powder X-ray diffraction measurement revealed the hexagonal structure of CdS nanocrystals. Morphological studies performed by scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) showed the island-like structure of CdS nanocrystals on PET substrates, as well as energy-dispersive X-ray spectroscopy (EDS) confirmed the stoichiometries of CdS nanocrystals. The optical properties of DTCs modified CdS nanocrystals were thoroughly investigated by ultraviolet-visible absorption spectroscopy (UV-vis) and fluorescence spectroscopy. The as-prepared DTCs present intrinsic hydrophobicity and strong affinity for CdS nanocrystals.

scholarly journals Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1141
Author(s):  
Georgia Basina ◽  
Hafsa Khurshid ◽  
Nikolaos Tzitzios ◽  
George Hadjipanayis ◽  
Vasileios Tzitzios
Keyword(s):  
Room Temperature ◽  
Colloidal Particles ◽  
Iron Pentacarbonyl ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
Organometallic Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Hot Injection ◽  
The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

Synthesis and Photoluminescence Properties of Novel SnO2 Zigzag Nanoribbons

2010 ◽  
Vol 97-101 ◽  
pp. 4213-4216
Author(s):  
Jian Xiong Liu ◽  
Zheng Yu Wu ◽  
Guo Wen Meng ◽  
Zhao Lin Zhan
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Ceramic Boat

Novel single-crystalline SnO2 zigzag nanoribbons have been successfully synthesized by chemical vapour deposition. Sn powder in a ceramic boat covered with Si plates was heated at 1100°C in a flowing argon atmosphere to get deposits on a Si wafers. The main part of deposits is SnO2 zigzag nanoribbons. They were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). SEM observations reveal that the SnO2 zigzag nanoribbons are almost uniform, with lengths near to several hundred micrometers and have a good periodically tuned microstructure as the same zigzag angle and growth directions. Possible growth mechanism of these zigzag nanoribbons was discussed. A room temperature PL spectrum of the zigzag nanoribbons shows three peaks at 373nm, 421nm and 477nm.The novel zigzag microstructures will provide a new candidate for potential application.

Preparation and Properties of Nano-Crystalline Cellulose Electro-Rheological Fluid

2015 ◽  
Vol 815 ◽  
pp. 217-221
Author(s):  
Ling Li Xu ◽  
Xing Ling Shi ◽  
Qing Liang Wang
Keyword(s):  
Room Temperature ◽  
Silicone Oil ◽  
Strong Acid ◽  
Crystalline Cellulose ◽  
Methyl Silicone ◽  
Shearing Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Crystalline ◽  
Transmission Electron

nanocrystalline cellulose (NCC) was prepared from micro-crystalline cellulose (MCC) by strong acid hydrolysis. The characteristics of such particle were studied by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. Electro-rheological fluids (ERF) were prepared by dispersing NCC and MCC in methyl-silicone oil, and their ER effects were measured. Experimental results indicated that NCC ERF exhibited a remarkable ER effect. The highest static shearing stress of NCC ERF (3.5 g/ml) was 5.1 kPa at the room temperature under a 4 .2 kV/mm electric field, increased about 5.5 times compared to MCC ERF, and sedimentation of NCC ERF was not observed even after 60 days.

New method for the production of bulk amorphous materials of Nd–Fe–B alloys

2005 ◽  
Vol 20 (3) ◽  
pp. 563-566 ◽  
Author(s):  
Tetsuji Saito ◽  
Hiroyuku Takeishi ◽  
Noboru Nakayama
Keyword(s):  
Electron Microscopy ◽  
Amorphous Materials ◽  
Room Temperature ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons

We report a new compression shearing method for the production of bulk amorphous materials. In this study, amorphous Nd–Fe–B melt-spun ribbons were successfully consolidated into bulk form at room temperature by the compression shearing method. X-ray diffraction and transmission electron microscopy studies revealed that the amorphous structure was well maintained in the bulk materials. The resultant bulk materials exhibited the same magnetic properties as the original amorphous Nd–Fe–B materials.

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