Structure and Magnetic Properties of Co, Ni, Mn, Cr and Cu Substituted Magnetites

1998 ◽  
Vol 517 ◽  
Author(s):  
M. Sorescu ◽  
D. Mihaila-Tarabasanu ◽  
L. Diamandescu
Keyword(s):  
Room Temperature ◽  
Random Distribution ◽  
Particle Diameter ◽  
Point Of View ◽  
Site Preference ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Saturation Magnetic Moment ◽  
Transmission Electron ◽  
Transmission Mössbauer Spectroscopy

AbstractCo, Ni, Mn, Cr and Cu substituted magnetites were prepared by the hydrothermal method at 300°C, with concentrations x ranging from 8.2 to 12.5%. Transmission electron microscopy determined the average particle diameter <Φ> to be in the hundred of nm range and the morphological modifications induced by the various substitutions employed. Hysteresis loop measurements were performed to determine the coercive field Hc and saturation magnetic moment ms. While Hc decreased with increasing <Φ>, the particle shape was found to play an important role in explaining the dependence of ms on <Φ>. Transmission Mössbauer spectroscopy was used to determine the site preference of the substitutions and their effect on the hyperfine magnetic fields. The room temperature Mossbauer spectra were analyzed assuming a random distribution of substitutents using the binomial distribution from the ionic crystal point of view. Superparamagnetic particles were observed at room temperature in the case of Cu and Cr substituted magnetites.

scholarly journals Morphology and Degradation of Multicompartment Microparticles Based on Semi-Crystalline Polystyrene-block-Polybutadiene-block-Poly(L-lactide) Triblock Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4358
Author(s):  
Nicole Janoszka ◽  
Suna Azhdari ◽  
Christian Hils ◽  
Deniz Coban ◽  
Holger Schmalz ◽  
...  
Keyword(s):  
Cross Sections ◽  
Ring Opening ◽  
Particle Diameter ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Selective Degradation ◽  
The Core ◽  
Transmission Electron ◽  
And Control ◽  
Triblock Terpolymers

The confinement assembly of block copolymers shows great potential regarding the formation of functional microparticles with compartmentalized structure. Although a large variety of block chemistries have already been used, less is known about microdomain degradation, which could lead to mesoporous microparticles with particularly complex morphologies for ABC triblock terpolymers. Here, we report on the formation of triblock terpolymer-based, multicompartment microparticles (MMs) and the selective degradation of domains into mesoporous microparticles. A series of polystyrene-block-polybutadiene-block-poly(L-lactide) (PS-b-PB-b-PLLA, SBL) triblock terpolymers was synthesized by a combination of anionic vinyl and ring-opening polymerization, which were transformed into microparticles through evaporation-induced confinement assembly. Despite different block compositions and the presence of a crystallizable PLLA block, we mainly identified hexagonally packed cylinders with a PLLA core and PB shell embedded in a PS matrix. Emulsions were prepared with Shirasu Porous Glass (SPG) membranes leading to a narrow size distribution of the microparticles and control of the average particle diameter, d ≈ 0.4 µm–1.8 µm. The core–shell cylinders lie parallel to the surface for particle diameters d < 0.5 µm and progressively more perpendicular for larger particles d > 0.8 µm as verified with scanning and transmission electron microscopy and particle cross-sections. Finally, the selective degradation of the PLLA cylinders under basic conditions resulted in mesoporous microparticles with a pronounced surface roughness.

MAGNETIC PROPERTIES OF γ-Fe2O3 NANOPARTICLES

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4422-4425 ◽  
Author(s):  
B. J. CHOI ◽  
S. H. KIM ◽  
Y. T. JEON ◽  
J. Y. MOON ◽  
G. H. LEE ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Lattice Constant ◽  
Room Temperature ◽  
Bulk Material ◽  
Particle Diameter ◽  
Average Particle ◽  
Face Centered Cubic ◽  
Fe2o3 Nanoparticles ◽  
Average Particle Diameter ◽  
Face Centered

We produced maghemite (γ- Fe 2 O 3) nanoparticles with average particle diameters of 6, 7, and 12 nm and investigated their magnetic properties. The structure was determined to be face centered-cubic with a lattice constant of a = 8.350±2 Å, similar to the bulk material for all samples. We observed that the γ- Fe 2 O 3 nanoparticles, with average particle diameters of 6 and 7 nm, were superparamagnetic at room temperature with blocking temperatures of 138 and 168 K, respectively. Those with an average particle diameter of 12 nm are ferrimagnetic at room temperature.

Preparation and pharmacokinetics of cefquinome sulfate liposomes in goats

2018 ◽  
Author(s):  
Haigang Wu ◽  
Jinni Liu ◽  
Gugangke Xu ◽  
Zhaowei Ye ◽  
Jicheng Liu and Benchi Yi
Keyword(s):  
Plasma Concentration ◽  
Particle Diameter ◽  
Entrapment Efficiency ◽  
Maximum Plasma Concentration ◽  
Maximum Plasma ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Ethanol Injection ◽  
Elimination Half ◽  
Time Point

We evaluated the pharmacokinetics of cefquinome sulfate (CEF) liposomes in eight healthy goats following intramuscular administration at 4 mg/kg. The average particle diameter of CEF liposomes prepared by the ethanol injection method was 335nm with a CEF entrapment efficiency of 69.56%. The elimination half-life (t1/2b) of CEF liposomes was 33.04h compared with 16.21 h for CEF injected without carrier (p less than 0.05). The area under the concentration curve (AUC) for CEF liposomes was approximately three-times greater than for CEF alone (P less than 0.05). The time-point of maximum plasma concentration of the drug (Tp) and the maximum plasma concentration (Cmax) were 4.38 h and 1.99 ìg/mL for CEF liposomes, compared with 1.86 h and 3.55 ìg/mL for CEF without carrier, respectively. 

Consolidation Features of Aluminum-Alumina Compositions by Powder Metallurgy Methods

2016 ◽  
Vol 254 ◽  
pp. 110-115
Author(s):  
Mihai Ovidiu Cojocaru ◽  
Mihaela Raluca Condruz ◽  
Florică Tudose
Keyword(s):  
Solid Phase ◽  
Particle Diameter ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composites ◽  
Average Particle ◽  
Matrix Composites ◽  
Aluminum Particles ◽  
Transmission Electron ◽  
Tapped Density ◽  
Powder Metallurgy Methods

In this paper was followed the processing flow of aluminum-alumina compositions (10÷20% alumina) in powder state, aiming to obtain aluminum matrix composites reinforced with alumina particles, starting from selecting and mixing the grading fraction of both components reaching up to sintering; it was analyzed the way in which reflects the variation of grading fraction ratio (expressed through average particle diameter in the analyzed fractions limits) on the level of technological interest features: apparent density, tapped density, flowability, presability and on densification after sintering (in various environments). By transmission electron microscopy was observed that aluminum particles showed on the surface a nanoscale oxide film, so the sintering occurs between congeneric areas – by solid phase sintering mechanisms [1, 2, 3]. The analysis of thermophysical properties revealed a decrease of thermal diffusivity at an increase of alumina, simultaneous with the decrease of the densification level.

Research on the Efficient Application of Silica Fume in High-Tech Cement-Based Materials

2011 ◽  
Vol 374-377 ◽  
pp. 1537-1540
Author(s):  
Dong Lin ◽  
Zi Yun Wen
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Packing Density ◽  
Particle Diameter ◽  
High Tech ◽  
Average Particle ◽  
Average Particle Diameter ◽  
Cement Based Materials ◽  
Pre Treatment

The comparison experiments are carried out at different silica fume dosage between the silica fume with pre-treatment and the silica fume without pre-treatment. The results show that the pre-treatment of silica fume improved the strength greatly and the silica fume dosage corresponding to the strength peak somewhat moved forward from 0.20 for the cement-based materials with pre-treatment of silica fume to 0.21 for the cement-based materials without pre-treatment of silica fume. The particles distribution experiment results indicate that after the pre-treatment of silica fume, the average particle diameter of silica fume reduced from 2.865μｍto 0.151μｍ. Based on Aim-Goff model, it is concluded that the increase in the compressive strength and flextural strength of cement-based materials with pre-treatment of silica fume, are attributed to the dispersion of silica fume agglomeration and the increase in the packing density of the cement-based materials.

Study on Synthesis of Starch Based Polymer Microspheres and Adsorption Behavior for Lead Ions

2014 ◽  
Vol 1004-1005 ◽  
pp. 311-314
Author(s):  
Yang Zhao ◽  
Jian Wei Ren
Keyword(s):  
Particle Diameter ◽  
Atomic Absorption Spectrophotometry ◽  
Adsorption Behavior ◽  
Lead Ions ◽  
Average Particle ◽  
Polymer Microspheres ◽  
Average Particle Diameter ◽  
Polymer Microsphere ◽  
Starch Microsphere ◽  
Absorption Spectrophotometry

The starch based polymer microspheres were synthesized in the system of the inverse emulsion polymerization. These polymer microspheres were characterized by Scanning Electron Microscope and Grain Size Analyzer. Adsorption behavior of starch based polymer microspheres for Pb2+ was investigated by atomic absorption spectrophotometry. The results showed that the average particle diameter of starch based polymer microspheres was about 43.9 μm, and surface of starch microsphere was rough and porous which could be beneficial to form adsorption layer. And the starch based polymer microsphere exhibited good adsorption of lead ions.

scholarly journals Deposits of iron oxides in the human globus pallidus

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 291-298
Author(s):  
Helena Svobodová ◽  
Jana Hlinková ◽  
Pavol Janega ◽  
Daniel Kosnáč ◽  
Barbora Filová ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Human Brain ◽  
Iron Oxides ◽  
Globus Pallidus ◽  
Room Temperature ◽  
Hysteresis Loops ◽  
Point Of View ◽  
Zero Field ◽  
Fixed Temperature ◽  
Transmission Electron

Abstract Samples taken from the human brain (Globus Pallidus) have been investigated by physical techniques such as light microscopy, scanning electron microscopy, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. SEM-EDX/TEM investigation reveals multielemental composition of hematite and magnetite nanocrystals with sizes ranging from 40 nm to 100 nm and hematite microcrystals from 3 μm to 7 μm. Room temperature Mössbauer spectra show quadrupole doublets assigning to hematite and ferrihydrite. SQUID measurements of temperature dependence of the mass magnetic susceptibility between T = 2 – 300 K at DC field B0 = 0.1 T, the field dependence of the mass magnetization taken at the fixed temperature T0 = 2.0 and 4.6 K and the zero-field cooled and field cooled magnetization experiments (ZFCM/FCM) confirm a presence of ferrimagnetic phases such as maghemite and/or magnetite with hysteresis loops surviving until the room temperature. Differences between these measurements from the point of view of iron oxides detected can indicate important processes in human brain and interactions between ferritin as a physiological source of iron and surrounding environment.

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

Comparison of Aluminum Powder Average Particle Diameter Values Determined by Various Methods

1982 ◽  
Vol 10 (4) ◽  
pp. 162 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
RL Meltzer ◽  
MB Vieth ◽  
SW Ping
Keyword(s):  
Aluminum Powder ◽  
Particle Diameter ◽  
Average Particle ◽  
Average Particle Diameter

DIELECTRIC PROPERTIES OF ULTRAFINE Zn-DOPED CaCu3Ti4O12 CERAMIC

2012 ◽  
Vol 02 (01) ◽  
pp. 1250007 ◽  
Author(s):  
LAXMAN SINGH ◽  
U. S. RAI ◽  
K. D. MANDAL ◽  
MADHU YASHPAL
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Room Temperature ◽  
Single Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sintered Powder

Ultrafine powder of CaCu2.80Zn0.20Ti4O12 ceramic was prepared using a novel semi-wet method. DTA/TG analysis of dry powder gives pre-information about formation of final product around 800°C. The formation of single phase was confirmed by X-ray diffraction analysis. The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm, respectively. Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic. Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

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