scholarly journals Enhancement of Neel Relaxation at Magnetic Heating Performance of Iron Oxide Nanoparticles 

2021 ◽  
Author(s):  
Musa Can ◽  
Chasan Bairam ◽  
Seda Aksoy ◽  
Serap Kuruca ◽  
Zerrin Aktaş ◽  
...  
Keyword(s):  
Sol Gel ◽  
Specific Effect ◽  
Silica Coating ◽  
Relaxation Mechanism ◽  
Superparamagnetic Nanoparticles ◽  
Interparticle Spacing ◽  
Heating Performance ◽  
Magnetic Heating ◽  
Two Parameters ◽  
Néel Relaxation

Abstract The study is based on understand the titanium (Ti) doping effect to enhance the Neel relaxation at magnetic heating performance of magnetite (Fe3O4). Ti doped magnetite ((Fe1-x,Tix)3O4; x= 0.02, 0.03 and 0.05) superparamagnetic nanoparticles were synthesized via sol-gel technique. The analyses were performed for (Fe1-x,Tix)3O4 and core-shell (SiO2 coated (Fe1-x,Tix)3O4) nanoparticles in order to understand the influence of silica coating on the magnetic properties of nanoparticles. The target of study to enhance the Neel relaxation mechanism on magnetic heating. The interparticle spacing and Ti amount were two parameters that we focused on the study. The results provided that coating with SiO2 has no specific effect on heating performance of (Fe1-x,Tix)3O4 nanoparticles. While the increase in temperature (ΔT) under 150 kHz RF signal reached up to 22oC in 10 minutes for SiO2 coated (Fe0.97,Ti0.03)3O4 nanoparticles, which was very close value of uncoated Fe3O4 nanoparticles.

Development of temporal spectroscopic properties for Xerogel matrices doped with Rhodamine 6G dye

Open Physics ◽  
2006 ◽  
Vol 4 (3) ◽  
Author(s):  
Abbas Al-Wattar ◽  
Baha Chiad ◽  
Wesam Twej ◽  
Sarmed Al-Awadi
Keyword(s):  
Fluorescence Spectra ◽  
Rhodamine 6G ◽  
Sol Gel ◽  
Blue Shift ◽  
Spectroscopic Properties ◽  
Dye Molecules ◽  
Absorption And Fluorescence Spectra ◽  
Silica Network ◽  
Sol Gel Process ◽  
Two Parameters

AbstractThe solid host of a laser dye modifies its spectroscopic properties with respect to its liquid host. During the Sol-Gel process the dye molecules suffer from changing their environment. Two parameters affect this matter, the change in the concentration due to the evaporation of the solvent (drying) and the caging of dye molecules inside the pores or attachment to the silica network. Rhodamine 6G absorption and fluorescence spectra with different concentrations, during Sol-Gel time processing, have been studied. Both, absorption and fluorescence spectra of the dye in the solid host, for different concentrations, show a blue-shift relative to its liquid phase.

Rapid Synthesis and Characterization of Maghemite Nanoparticles

2008 ◽  
Vol 8 (2) ◽  
pp. 861-866 ◽  
Author(s):  
Bilsen Tural ◽  
Macit Özenbaş ◽  
Selçuk Atalay ◽  
Mürvet Volkan
Keyword(s):  
Particle Size ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Volume Ratio ◽  
Silica Matrix ◽  
Superparamagnetic Nanoparticles ◽  
Maghemite Nanoparticles ◽  
Gelation Temperature ◽  
Iron Oxide Particles ◽  
Evaporation Surface

Fe2O3–SiO2 nanocomposites were prepared by a sol–gel method using various evaporation surface to volume (S/V) ratios ranging from 0.03 to 0.2. The Fe2O3–SiO2 sols were gelated at various temperatures ranging from 50 °C to 70 °C, and subsequently they were calcined in air at 400 °C for 4 hours. The structure and the magnetic properties of the prepared Fe2O3–SiO2 nanocomposites were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), differential thermal analysis (DTA), and vibrating sample magnetometer (VSM) measurements. The gelation temperature of the Fe2O3–SiO2 sols influenced strongly the particle size and crystallinity of the maghemite nanoparticles. It was observed that the particle size of maghemite nanoparticles increased with the increasing of the gelation temperature of the sols, which may be due to the agglomeration of the maghemite particles at elevated temperatures inside the microporosity of the silica matrix during the gelation process, and the subsequent calcination of these gels at 400 °C resulted in the formation of large size iron oxide particles. Magnetization studies at temperatures of 10, 195, and 300 K showed superparamagnetic behavior for all the nanocomposites prepared using the evaporation surface to volume ratio (S/V) of 0.1, 0.2, 0.09, and 0.08. The saturation magnetization, Ms, values measured at 10K were 5.5, 8.5, and 9.5 emu/g, for the samples gelated at 50, 60, and 70 °C, respectively. At the gelation temperature of 70 °C, γ-Fe2O3 crystalline superparamagnetic nanoparticles with the particle size of 9±2 nm were formed in 12 hours for the samples prepared at the S/V ratio of 0.2.

scholarly journals Difference between Brownian and Néel relaxation mechanisms in a magnetizing field

2021 ◽  
pp. 14-20
Author(s):  
Alexander V. Lebedev ◽  
Keyword(s):  
Relaxation Time ◽  
Oleic Acid ◽  
High Frequency ◽  
Cobalt Ferrite ◽  
Magnetic Moments ◽  
Relaxation Mechanism ◽  
Dynamic Susceptibility ◽  
Magnetite Particles ◽  
Magnetizing Field ◽  
Néel Relaxation

Measurements of the dynamic susceptibility of a magnetic fluid based on cobalt ferrite particles stabilized in water by a double surfactant layer have been carried out. Cobalt ferrite, in comparison with magnetite, has a significantly higher energy of magnetic anisotropy. Therefore, for particles of cobalt ferrite, the Brownian mechanism of relaxation of magnetic moments is characteristic. The Debye (with a finite relaxation time) contribution to the dynamic susceptibility and the high-frequency (dispersionless) contribution are distinguished by constructing Cole-Cole diagrams. It was found that with an increase in the magnetizing field, the Debye contribution to the dynamic susceptibility decreases, while the high-frequency one (having a zero relaxation time) remains unchanged. The indicated property of the dynamic susceptibility of a fluid with a Brownian relaxation mechanism is radically different from the properties of the susceptibility of a fluid with Néel particles. Previously, measurements were made of the susceptibility of a fluid based on magnetite particles stabilized with oleic acid in kerosene. The magnetite particles have significantly lower anisotropy energy and are characterized by the predominance of the Néel relaxation mechanism. Turning on the magnetizing field caused a decrease in both the Debye part of the susceptibility and the high-frequency part of the susceptibility of magnetite particles.

scholarly journals Silica coating of indium phosphide nanoparticles by a sol–gel method and their photobleaching properties

2019 ◽  
Vol 1 (12) ◽  
Author(s):  
Masaya Kambayashi ◽  
Noriko Yamauchi ◽  
Kouichi Nakashima ◽  
Masaki Hasegawa ◽  
Yuki Hirayama ◽  
...  
Keyword(s):  
Indium Phosphide ◽  
Sol Gel ◽  
Silica Coating ◽  
Gel Method ◽  
Sol Gel Method

scholarly journals The effect of silica-coating by sol-gel process on resin-zirconia bonding

2013 ◽  
Vol 32 (1) ◽  
pp. 165-172 ◽  
Author(s):  
Christie Ying Kei LUNG ◽  
Edwin KUKK ◽  
Jukka Pekka MATINLINNA
Keyword(s):  
Sol Gel ◽  
Silica Coating ◽  
Sol Gel Process

An Effective Approach to Improve the Oxidation Resistance of Ti-6Al-4V Alloy by Combination of Phosphorization and Silica Coating

2011 ◽  
Vol 148-149 ◽  
pp. 534-537
Author(s):  
Chun Xiang Gao
Keyword(s):  
Oxidation Resistance ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Sol Gel ◽  
Synergetic Effect ◽  
Silica Coating ◽  
Dip Coating ◽  
Sio2 Coating ◽  
Amorphous Sio2 ◽  
Dip Coating Technique

A very effective approach to improve the oxidation resistance of Ti-6Al-4V alloy was proposed. The Ti-6Al-4V alloy was firstly phosphated and then coated by silica using sol-gel dip-coating technique. A duplex layer of TiP2O7 and amorphous silica was synthesized at the alloy surface. The isothermal and cyclic oxidation behavior of the treated alloy with silica coating and the corresponding bare alloy was investigated at 600 oC in static air to investigate the synergetic effect of phosphorization and amorphous SiO2 coating on the oxidation resistance of the alloy. The isothermal and cyclic oxidation resistances of the alloy were greatly improved.

Organic Hydrogel Templates for Tunable Mesoporous Silica Hybrid Materials

2015 ◽  
Vol 1721 ◽  
Author(s):  
Jennifer L. Kahn ◽  
Necla Mine Eren ◽  
Osvaldo Campanella ◽  
Sherry L. Voytik-Harbin ◽  
Jenna L. Rickus
Keyword(s):  
Mesoporous Silica ◽  
Hybrid Materials ◽  
Collagen Fibril ◽  
Film Formation ◽  
Sol Gel ◽  
Collagen Matrix ◽  
Silica Coating ◽  
Absolute Amount ◽  
Microstructural Properties ◽  
Synthesis Conditions

ABSTRACTPorous coatings at the surface of living cells have application in human cell transplantation by controlling the transport of biomolecules to and from the cells. Sol-gel-derived mesoporous silica materials are good candidates for such coatings, owing to their biocompatibility, facile solution-based synthesis conditions, and thin film formation. Diffusion and transport across the coating correlates to long-range microstructural properties, including pore size distribution, porosity, and pore morphology. Here, we investigated collagen-fibril matrices with known biocompatibility to serve as templating systems for directed silica deposition. Type 1 collagen oligomers derived from porcine skin are extensively characterized such that we can predict and customize the final collagen-fibril matrix with respect to fibril density, interfibril branching and viscoelasticity. We show that these matrices template and direct the deposition of mesoporous silica at the level of individual collagen fibrils. We varied the fibril density, silicic acid concentration, and time of exposure to silicifying solution and characterized the resulting hybrid materials by scanning electron microscopy, energy-dispersive x-ray spectroscopy, and rheology. Microstructural properties of the collagen-fibril template are preserved in the silica surface of hybrid materials. Results for three different collagen fibril densities, corresponding to shear storage moduli of 200 Pa, 1000 Pa, and 1600 Pa, indicate that increased fibril density increases the absolute amount of templated silica when all other silica synthesis conditions are kept constant. Additionally, mechanical properties of the hybrid material are dominated by the presence of the silica coating rather than the starting collagen matrix stiffness.

New Magnetic Materials Produced By The Sol-Gel Process: A Possibility Of Producing Exotic Devices

1986 ◽  
Vol 73 ◽  
Author(s):  
G. Kordas
Keyword(s):  
Line Width ◽  
Sol Gel ◽  
Resonance Field ◽  
Relaxation Mechanism ◽  
Hydrogen Atmosphere ◽  
Film Plane ◽  
Local Fields ◽  
Oxide Thin Film ◽  
Sol Gel Process ◽  
Oriented Parallel

ABSTRACTFerromagnetic resonance (FMR) spectra of an iron-oxide thin film with a thickness of 70 A were recorded between 100 and 410 K at 9.5 GHz after heat treatment at about 500 °C in hydrogen atmosphere. The FMR-signal of this film consisted of two components (A and B) when the film plane was oriented parallel to the external fieTp The intensity of these components is not proportional toT3/2 in the range from 100 to 410 K. The line width of the A-component is determined by inhomogeneities in the magnetic structure. The line width of the B-component may be influenced by the spin-spin relaxation mechanism and skin effect. The temperature behavior of the resonance field of the A- and B-components was tentatively attributed to variation of the local fields with the temperature of measurements.

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