Fabrication of Ferromagnetic Fe/Mullite Composite Materials Via Sol-Gel Processing

1988 ◽  
Vol 132 ◽  
Author(s):  
Deanne P. Yamato ◽  
Abraham L. andis ◽  
Teh S. Kuan
Keyword(s):  
Particle Size ◽  
Composite Materials ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Iron Particle ◽  
Ferromagnetic Hysteresis ◽  
Gel Technique ◽  
Gel Processing ◽  
Iron Concentrations

ABSTRACTThe sol-gel technique was used to fabricate α-Fe/mullite composite materials with iron concentrations ranging from 20–60 wt.% Fe. Microscopy studies showed the microstructure to consist of particulate α-Fe dispersed uniformly throughout a mullite matrix. Iron particle size, estimated by TEM, ranged from 20–500 nm. The materials exhibited ferromagnetic hysteresis with saturation magnetization Ms values as high as 115 EMU/g.

Study of structural, electrical, optical and magnetic properties of Hexaferrite–Polyaniline nanocomposites

2019 ◽  
Vol 33 (13) ◽  
pp. 1950134 ◽  
Author(s):  
Muhammad Ajmal ◽  
M. U. Islam
Keyword(s):  
Saturation Magnetization ◽  
In Situ Polymerization ◽  
Sol Gel ◽  
Electric Polarization ◽  
Room Temperature Resistivity ◽  
Magnetic Studies ◽  
Xrd Pattern ◽  
Gel Technique ◽  
Pani Matrix

Y-type hexagonal ferrite (CaBaCo2Ga[Formula: see text]Fe[Formula: see text]O[Formula: see text]) was synthesized by sol–gel technique. The ferrite–polymer composites (1−x)CaBaCo2Ga[Formula: see text]Fe[Formula: see text]O[Formula: see text]+(x)polyaniline (x=0.25, 0.50, 0.75, 1) namely PF1, PF2, PF3 and polyaniline (PANI) were synthesized by in situ polymerization. The synthesized samples were characterized by XRD, SEM, electrical and dielectric measurements, optical and magnetic studies. XRD pattern reveals a broad peak of polyaniline which is an indication of amorphous nature of PANI. Room-temperature resistivity increases from 2.14 × 101 [Formula: see text]cm to 2.78 × 10[Formula: see text]cm as ferrite content increases due to resistive behavior of the ferrite particles dispersed in the PANI matrix. The value of dielectric constant decreases at fixed frequency with increasing concentration of ferrite filler which is predominantly due to exchange of electrons between Fe[Formula: see text] and Fe[Formula: see text] ions that ultimately results in enhancement of electric polarization and conductivity. The optical bandgap increases with increasing amount of ferrite in the composites. The saturation magnetization and remanence increase with the increase of ferrite filler amount in PANI matrix whereas coercivity decreases. The decrease in coercivity and increase in saturation magnetization are related to Brown’s relation. The present nanocomposite samples may be the best candidates for electromagnetic shielding.

Modified Sol-Gel Processing of NiCr2O4 Nanoparticles; Structural Analysis and Optical Band Gap

2017 ◽  
Vol 36 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Morteza Enhessari ◽  
Ali Salehabadi ◽  
Salah Khanahmadzadeh ◽  
Kamal Arkat ◽  
Jalal Nouri
Keyword(s):  
Particle Size ◽  
Band Gap ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Complexing Agent ◽  
Minor Phase ◽  
Absorption Bands ◽  
Ammonium Dichromate ◽  
Electrical Devices ◽  
Gel Processing

AbstractNickel Chromite nanoparticles were successfully synthesized via a modified sol-gel method using nickel acetate and ammonium dichromate in melted stearic acid as a complexing agent. The diffractograms of the nanoparticles confirmed a pure formation of NiCr2O4 spinel without any minor phase. The coordination structure of as prepared nanoparticles shows a series of absorption bands below 1,000 cm−1 were evidenced the M-O (Cr-O, Ni-O) bond in the sample. Optical band gap, magnetic properties and color parameters (L*.a*.b*) indicates that the final nanoparticles are optically and magnetically active. The particle size of NiCr2O4 was calculated using Scherrer equation at about 24 nm. Optical band gap obtained at 1.7 eV indicating that NiCr2O4 nanoparticles are semiconductor material and can be used in electrical devices.

Preparation and Magnetic Properties of Monodisperse Nanocomposite Hollow Spheres

2007 ◽  
Vol 998 ◽  
Author(s):  
Chun-Rong Lin ◽  
Cheng-Chien Wang ◽  
I-Han Chen
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Saturation Magnetization ◽  
Magnetic Measurements ◽  
Spinel Ferrite ◽  
Sol Gel ◽  
Hollow Spheres ◽  
Core Shell ◽  
Ferromagnetic Behavior ◽  
Mixed Gas

ABSTRACTWe present a simple process to prepare the hollow ceramic (CoFe2O4/SiO2) composite nanospheres and hollow alloy (Co33Fe67/SiO2) composite nanospheres. The hollow CoFe2O4/SiO2 composite nanospheres were prepared by calcining polymer/CoFe2O4/SiO2 core/shell composite spheres which were synthesized by the sol-gel method following the chemical co-precipitation. In a typical process, the monodisperse polymer poly(MMA-co-MAA) latex (450 nm) was used as a core template. To create hollow CoFe2O4/SiO2 spherical structures with various sizes of CoFe2O4 nanoparticles, the hybrid PMMA/CoFe2O4/SiO2 core-shell spheres were subsequently calcined in the temperature range from 450 to 900°C for 4h. On the other hand, the hollow Co33Fe67/SiO2 composite nanospheres were formed by reduction of hollow CoFe2O4/SiO2 nanospheres in a stream of H2/Ar mixed gas at 900°C for 8 hrs. X-ray diffraction pattern shows that the coated phase of the hollow CoFe2O4/SiO2 composite nanospheres has a cubic spinel ferrite structure. Based on the thermogravimetric analysis (TGA), we found that the content of CoFe2O4 is 73 wt% in the hollow CoFe2O4/SiO2 composite shell. The scanning electron microscope and transmission electron microscope photographs show that the hollow spheres are uniform. According to the line scanning EDX analysis of the cross section of hollow spheres, the SiO2 is not only coated on the surface of sphere but also distributed over the shell of hollow sphere. The thickness of shell of hollow spheres is about 40 nm. Magnetic measurements show that the saturation magnetization is clearly decreases as the magnetic particle size decreased. This phenomenon can be interpreted as the effect of surface spin canting when the particle size is reduced. As for the hollow alloy (Co33Fe67/SiO2) composite nanospheres, the magnetic phase has a body-centered cubic structure and an average crystallite size of 28.7 nm. This alloy nanospheres exhibit a ferromagnetic behavior with saturation magnetization of 170 emu/g, coercivity of 250 Oe, and Curie temperature of 968 °C. Due to metallic and ferromagnetic behavior of Co33Fe67 nanoparticles, these hollow spheres can be used as a lightweight electromagnetic wave absorber.

Microwave processing CaO-Al203-SiO2 Glass Using Sol-Gel Technique

1996 ◽  
Vol 430 ◽  
Author(s):  
Y. Zhou ◽  
O. Van der Biest ◽  
C. Groffils ◽  
P. J. Luypaert
Keyword(s):  
Power Level ◽  
Sol Gel ◽  
Structural Evolution ◽  
Single Mode ◽  
Processing Parameters ◽  
Incident Power ◽  
Sio2 Glass ◽  
Gel Technique ◽  
Microwave Applicator ◽  
Gel Processing

AbstractGels in the CaO-A12O3-SiO2 (CAS) system were successfully converted into glass in a single mode, tuneable, cylindrical microwave applicator, operating at 2.45 GHz in the TM012 mode. Transparent glasses were formed as a result of the direct microwave heating of homogeneous CAS gels to well above their melting temperature (1170°C). The effect of processing parameters, such as incident power level, sample mass and location, and thermal insulation has been investigated. The excellent coupling of the CAS gel with microwave can be understood from the structural evolution during sol-gel processing.

Preparation of LSMO/PLZT Composite Film by Sol-Gel Technique and its Ferroelectric and Ferromagnetic Properties

2015 ◽  
Vol 815 ◽  
pp. 166-170
Author(s):  
Zong Fan Duan ◽  
Juan Ning Wei ◽  
Ying Cui ◽  
Gao Yang Zhao
Keyword(s):  
Composite Film ◽  
Sol Gel ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Single Crystal Substrate ◽  
X Ray Diffraction ◽  
Ferromagnetic Properties ◽  
Crystal Substrate ◽  
Ferromagnetic Hysteresis ◽  
Gel Technique

La0.67Sr0.33MnO3 (LSMO)/Pb0.92La0.08Zr0.65Ti0.35O3 (PLZT) composite film was fabricated on a (001) LaAlO3 (LAO) single crystal substrate by a sol-gel technique. The results from X-ray diffraction (XRD) indicated that LSMO and PLZT could grow successively on LAO substrate with (001) preferred orientation. The ferroelectric and ferromagnetic properties of LAO/LSMO/PLZT composite film were also investigated. The results showed that the remnant polarization Pr, and coercive field Ec of the composite film at room temperature were 36.38 μC/cm2 and 512.43 kV/cm respectively. Moreover, the composite film exhibited significant ferromagnetic hysteresis loops and soft magnetic behavior at temperatures lower than 250 K.

Effects of particle size on the phase transition in Pb(Zr, Ti)O3 grown by the sol–gel technique

1998 ◽  
Vol 34 (3-6) ◽  
pp. 326-331 ◽  
Author(s):  
R Castro-Rodrı́guez ◽  
M Quadrelli ◽  
E Vasco ◽  
F Calderón ◽  
F Leccabue ◽  
...  
Keyword(s):  
Phase Transition ◽  
Particle Size ◽  
Sol Gel ◽  
Gel Technique

Controlling the Particle Size of Quantum Dots Incorporated in Hybrid Materials

1998 ◽  
Vol 519 ◽  
Author(s):  
Francisco Del Monte ◽  
Yuhuan Xu ◽  
John D. Mackenzie ◽  
B. Claflin ◽  
G. Lucovsky
Keyword(s):  
Particle Size ◽  
Chemical Interaction ◽  
Quantum Confinement Effect ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
Aggregation Processes ◽  
Trifunctional Silane ◽  
Gel Technique

AbstractSemiconductor PbS quantum dot-doped Ormocers were successfully prepared by the sol-gel technique. Ormocers preparation was based on the use of trifunctional silane precursors at the solution stage. Formation of PbS particles took place in the pores of the Ormocers through lead precursor reaction with H2S gas. It was observed that temperature was an important factor in the reaction leading to the first appearance of PbS particles. The dot size of PbS was controlled through chemical interaction with the non-hydrolyzed groups of the trifunctional silane precursors. These groups prevent uncontrolled nucleation and aggregation processes during the particle formation and growth. The control of particle size was studied at different conditions for nucleation and aggregation. Determination of the average particle size was done by XR-Diffraction. Optical absorption spectra were also measured at the UV-VIS wavelength range. Absorption edge blue shifts show the quantum confinement effect in these materials.

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