scholarly journals Effect of Silica Embedding on the Structure, Morphology and Magnetic Behavior of (Zn0.6Mn0.4Fe2O4)δ/(SiO2)(100−δ) Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2232
Author(s):  
Thomas Dippong ◽  
Iosif Grigore Deac ◽  
Oana Cadar ◽  
Erika Andrea Levei
Keyword(s):  
Crystallite Size ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Average Crystallite Size ◽  
Chemical Transformations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Crystallite Sizes ◽  
Ft Ir

The effect of SiO2 embedding on the obtaining of single-phase ferrites, as well as on the structure, morphology and magnetic properties of (Zn0.6Mn0.4Fe2O4)δ(SiO2)100−δ (δ = 0–100%) nanoparticles (NPs) synthesized by sol-gel method was assessed. The phase composition and crystallite size were investigated by X-ray diffraction (XRD), the chemical transformations were monitored by Fourier transform infrared (FT-IR) spectroscopy, while the morphology of the NPs by transmission electron microscopy (TEM). The average crystallite size was 5.3–27.0 nm at 400 °C, 13.7–31.1 nm at 700 °C and 33.4–49.1 nm at 1100 °C. The evolution of the saturation magnetization, coercivity and magnetic anisotropy as a function of the crystallite sizes were studied by vibrating sample magnetometry (VSM) technique. As expected, the SiO2 matrix shows diamagnetic behavior accompanied by the accidentally contribution of a small percent of ferromagnetic impurities. The Zn0.6Mn0.4Fe2O4 embedded in SiO2 exhibits superparamagnetic-like behavior, whereas the unembedded Zn0.6Mn0.4Fe2O4 behaves like a high-quality ferrimagnet. The preparation route has a significant effect on the particle sizes, which strongly influences the magnetic behavior of the NPs.

Microstructural characteristics and photoluminescence performance of nanograined thermally treated CeO2-TiO2 xerogels

2007 ◽  
Vol 22 (5) ◽  
pp. 1182-1187
Author(s):  
Amita Verma ◽  
A.K. Srivastava ◽  
N. Karar ◽  
Harish Chander ◽  
S.A. Agnihotry
Keyword(s):  
Electron Microscopy ◽  
Crystallite Size ◽  
Sol Gel ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Crystallite Sizes ◽  
Thermally Treated

Nanostructured thermally treated xerogels have been synthesized using a sol-gel process involving cerium (Ce) chloride heptahydrate and titanium (Ti) propoxide mixed in different Ce:Ti molar ratios. Structural features of the xerogels have been correlated with their photoluminescence (PL) response. The crystallite sizes in the samples lie in the nanorange. The x-ray diffraction and transmission electron microscopy results have confirmed the coexistence of CeO2 and TiO2 nanocrystallites in these xerogels. In general, a decrease in the CeO2 crystallite size and an increase in the TiO2 crystallite size are observed in the xerogels as a function of Ti content. Scanning electron microscopy results have evidenced the evolution of ordered structure in the xerogels as a function of TiO2 content. Although both of the phases (CeO2 and TiO2) have exhibited PL in ultraviolet and visible regions, the major luminescence contribution has been made by the CeO2 phase. The largest sized CeO2 crystallites in 1:1 thermally treated xerogel have led to its highest PL response. PL emission in the xerogels is assigned to their nanocrystalline nature and oxygen vacancy-related defects.

scholarly journals Synthesis of NiFe2O4 nanofibers by joint sol-gel and electrospinning technique

10.30544/387 ◽  
2018 ◽  
Vol 24 (3) ◽  
pp. 173-180
Author(s):  
Aleksandar Grujić ◽  
Vladan Ćosović ◽  
Jasna Stajić-Trošić ◽  
Aleksandar Ćosović ◽  
Mirko Stijepović ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Sol Gel ◽  
Morphological Characteristics ◽  
Magnetic Behavior ◽  
Composition Analysis ◽  
X Ray Diffraction ◽  
Electrospinning Technique ◽  
Web Structure ◽  
Crystallite Sizes ◽  
Ft Ir

In this study, electrospinning combined with sol-gel technique is applied in order to produce magnetic nickel ferrite (Ni-ferrite) nanofibers. The prepared Ni-ferrite gel was mixed with poly(vinylpyrrolidone) (PVP) solution which was used as a spinning aid to enable spinnability of the mixture. Structural and morphological characteristics of the as-spun ferrite gel/PVP composite web structure and calcinated Ni-ferrite nanofibers were analyzed using scanning electron microscopy (SEM). Phase composition analysis was carried out by Fourier-transform infrared (FT-IR) spectroscopy, X-Ray diffraction analysis (XRD) and 57Fe Mössbauer spectroscopy (MS). The obtained results suggest that the pure nanocrystalline NiFe2O4 dense mat to the almost coral-like structure of fibers with diameters ranging from hundreds of nanometers to few micrometers was obtained. The results of MS analysis revealed the existence of a crystallite size distribution within the material as well as the existence of a superparamagnetic fraction with very small crystallite sizes (<13nm). Magnetic behavior of the obtained material at elevated temperatures was also scrutinized using thermomagnetic measurements (TM) up to 800 °C.

Structure Analysis of Nanocrystalline MgO Aerogel Prepared by Sol-Gel Method

2007 ◽  
Vol 130 ◽  
pp. 203-206 ◽  
Author(s):  
Grzegorz Dercz ◽  
Lucjan Pająk ◽  
Krystian Prusik ◽  
Roman Pielaszek ◽  
Janusz J. Malinowski ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Magnesium Oxide ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Technique ◽  
Microscopy Images ◽  
Nanocrystalline Mgo

Wet gel obtained by sol-gel technique was dried in supercritical CO2 to prepare hydrated form of magnesium oxide. Calcination at 723 K under vacuum yielded nanocrystalline MgO aerogel. Structure studies were performed by X-ray diffraction, scanning and transmission electron microcopies. Electron microscopy images reveal rough, unfolded and ramified structure of solid skeleton. Specific surface area SBET was equal to 238 m2/g. X-ray pattern reveals the broadened diffraction lines of periclase, the only crystalline form of magnesium oxide. The gamma crystallite size distribution was determined using FW 5 4 / 5 1 M method proposed by R. Pielaszek. The obtained values of <R> and σ (measure of polydispersity) of particle size parameters are equal to 6.5 nm and 1.8 nm, respectively, whereas the average crystallite size estimated by Williamson-Hall procedure was equal to 6.0 nm. The obtained at Rietveld refinement Rwp, and S fitting parameters equal to 6.62% and 1.77, respectively, seem to be satisfactory due to the nanosize of MgO crystallites and because of the presence of amorphous phase.

scholarly journals Effect of Eu3+ Concentration on the BaAl2O4/CaAl4O7: x% Eu3+ (0 ≤ x ≤ 5.5) Mixed-Phase Nanophosphors Synthesized Using Citrate Sol-Gel Method

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Bamba Mahman ◽  
Mpho Enoch Sithole
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Mixed Phase ◽  
Nanometer Scale ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Crystallite Sizes ◽  
Gel Technique

A series of undoped mixed-phase BaAl2O4/CaAl4O7 (hereafter called BC) and doped BC: x% Eu3+ (0 < x ≤ 5.5) nanophosphors were successfully prepared by the citrate sol-gel technique. Their structure, morphology, and optical properties were studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD and SEM showed that all the BC:x% Eu3+ samples consisted of the crystalline structure of the mixed phases of both the BaAl2O4 and CaAl4O7 materials. The structure resembles more that of the BaAl2O4 than the CaAl4O7 phase. The TEM results suggest that the crystallite sizes are in the nanometer scale with rod-like particles. PL results showed multiple emission peaks located at 436, 590, 616, 656, and 703 nm, which were assigned to the intrinsic defects within the BC matrix, 5D0 ⟶ 7F1, 5D0 ⟶ 7F2, 5D0 ⟶ 7F3, and 5D0 ⟶ 7F4 transitions of Eu3+, respectively. The decay curves evidently showed that the nanophosphors have persistent luminescence. The Commission Internationale de l’Eclairage (CIE) analysis revealed that doping has tuned the emission colour from blue to orange-red. The results indicate that the Eu3+-doped samples can potentially be used in the orange/red-emitting phosphors.

scholarly journals Hydrothermal Synthesis, Characterization and Exploration of Photocatalytic Activities of Polyoxometalate: Ni-CoWO4 Nanoparticles

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 456
Author(s):  
Fahad A. Alharthi ◽  
Hamdah S. Alanazi ◽  
Amjad Abdullah Alsyahi ◽  
Naushad Ahmad
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Photocatalytic Activities ◽  
Ft Ir ◽  
Photocatalytic Reactions ◽  
Cobalt Tungstate

This study demonstrated the hydrothermal synthesis of bimetallic nickel-cobalt tungstate nanostructures, Ni-CoWO4 (NCW-NPs), and their phase structure, morphology, porosity, and optical properties were examined using X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), high resolution Transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) and Raman instruments. It was found that as-calcined NCW-NPs have a monoclinic phase with crystal size ~50–60 nm and is mesoporous. It possessed smooth, spherical, and cubic shape microstructures with defined fringe distance (~0.342 nm). The photocatalytic degradation of methylene blue (MB) and rose bengal (RB) dye in the presence of NCW-NPs was evaluated, and about 49.85% of MB in 150 min and 92.28% of RB in 90 min degraded under visible light. In addition, based on the scavenger’s study, the mechanism for photocatalytic reactions is proposed.

Effect of Synthesis Temperature on Particles Size and Morphology of Zirconium Oxide Nanoparticle

2017 ◽  
Vol 50 ◽  
pp. 18-31 ◽  
Author(s):  
Rudzani Sigwadi ◽  
Simon Dhlamini ◽  
Touhami Mokrani ◽  
Patrick Nonjola
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Zirconium Oxide ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Ft Ir

The paper presents the synthesis and investigation of zirconium oxide (ZrO2) nanoparticles that were synthesised by precipitation method with the effects of the temperatures of reaction on the particles size, morphology, crystallite sizes and stability at high temperature. The reaction temperature effect on the particle size, morphology, crystallite sizes and stabilized a higher temperature (tetragonal and cubic) phases was studied. Thermal decomposition, band structure and functional groups were analyzed by Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermo-gravimetric analysis (TGA) and Fourier transform infrared (FT-IR). The crystal structure was determined using X-ray diffraction. The morphology and the particle size were studied using (SEM) and (TEM). The shaped particles were confirmed through the SEM analysis. The transmission electron microscopic analysis confirmed the formation of the nanoparticles with the particle size. The FT-IR spectra showed the strong presence of ZrO2 nanoparticles.

X-ray structure and microstructure determination of the mixed sesquioxides (Eu1−xYbx)2O3prepared by a sol–gel process

2003 ◽  
Vol 36 (6) ◽  
pp. 1411-1416 ◽  
Author(s):  
Z. K. Heiba ◽  
Y. Akin ◽  
W. Sigmund ◽  
Y. S. Hascicek
Keyword(s):  
Crystallite Size ◽  
Rietveld Method ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Profile Fitting ◽  
Cationic Distribution ◽  
Sol Gel Process ◽  
Multiple Orders

Polycrystalline samples of (Eu1−xYbx)2O3(x= 0.0, 0.1, 0.2, 0.5, 0.8, 0.9 and 1.0) were synthesized by a sol–gel process. X-ray diffraction data were collected and the crystal structures were refined by the Rietveld method. All samples are found to have the same crystal system and formed solid solutions over the whole range ofx. The lattice parameters are found to vary linearly with the compositionx. The cationic distribution over the two non-equivalent sites 8band 24dof the space group Ia{\bar 3} is found to be random in the range 0.0 <x≤ 0.5 and preferential in the range 0.5 <x≤ 1.0. Replacing Eu3+and Yb3+by each other introduces slight changes in the atomic coordinates. Crystallite size and microstrain analysis are performed on single and multiple orders for each sample using profile fitting and the Warren–Averbach method. The obtained values of microstrain are correlated with the distribution of the rare earth (RE) ions over the two cationic sites of the structure. The average crystallite size ranges from 35 to 96 nm and the mean-square strain from 0.052 to 0.225 × 10−2.

Effect of Polymeric Milling Media on the Mechanosynthesis and Structural Properties of Nanocrystalline Hydroxyapatite

2009 ◽  
Vol 283-286 ◽  
pp. 98-105 ◽  
Author(s):  
Ali Shokuhfar ◽  
Bahman Nasiri-Tabrizi ◽  
Omid Gashti ◽  
Reza Ebrahimi-Kahrizsangi
Keyword(s):  
Crystallite Size ◽  
High Performance ◽  
Average Crystallite Size ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Mechanochemical Process ◽  
Structural Evaluation ◽  
Transmission Electron ◽  
Nanocrystalline Hydroxyapatite ◽  
Xrd Patterns

Mechanochemical process in polymeric vials has been carried out successfully to produce nanocrystalline hydroxyapatite (HAp) through two different reactions R1 and R2. Morphological properties and structural evaluation of obtained materials are studied by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). The obtained data show that the increase in milling time leads the increasing in lattice strain and decreasing in crystallite size. The average crystallite size of HAp is below 20 and 23 nm for R1 and R2 reactions, respectively. Based on XRD patterns and SEM/TEM micrographs, the possible formation mechanism of nanocrystalline hydroxyapatite by mechanochemical process in polymeric milling media is confirmed. Final results indicate that the nanocrystalline hydroxyapatite with low chemically stable contaminations and suitable morphology can be produced in Polyamide6 vials similar to stainless steel vials, therefore it seems that using polymeric vials could lead to a new way for the mass production of nanocrystalline hydroxyapatite with high performance, low contamination and cost and also suitable morphology.

scholarly journals Bi1−xEuxFeO3 Powders: Synthesis, Characterization, Magnetic and Photoluminescence Properties

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1465 ◽  
Author(s):  
Vasile-Adrian Surdu ◽  
Roxana Doina Trușcă ◽  
Bogdan Ștefan Vasile ◽  
Ovidiu Cristian Oprea ◽  
Eugenia Tanasă ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bismuth Ferrite ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Weak Ferromagnetism ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
Gel Technique ◽  
Comparative Results

Europium substituted bismuth ferrite powders were synthesized by the sol-gel technique. The precursor xerogel was characterized by thermal analysis. Bi1−xEuxFeO3 (x = 0–0.20) powders obtained after thermal treatment of the xerogel at 600 °C for 30 min were investigated by X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectroscopy, and Mössbauer spectroscopy. Magnetic behavior at room temperature was tested using vibrating sample magnetometry. The comparative results showed that europium has a beneficial effect on the stabilization of the perovskite structure and induced a weak ferromagnetism. The particle size decreases after the introduction of Eu3+ from 167 nm for x = 0 to 51 nm for x = 0.20. Photoluminescence spectroscopy showed the enhancement of the characteristic emission peaks intensity with the increase of Eu3+ concentration.

scholarly journals Study on the Photocatalytic and Antibacterial Properties of TiO2 Nanoparticles-Coated Cotton Fabrics

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2010 ◽  
Author(s):  
Guangyu Zhang ◽  
Dao Wang ◽  
Jiawei Yan ◽  
Yao Xiao ◽  
Wenyan Gu ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Cotton Fabric ◽  
Sol Gel ◽  
Antibacterial Properties ◽  
Average Crystallite Size ◽  
Cotton Fabrics ◽  
Tetrabutyl Titanate ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Scanning Electron Microcopy

Herein, the amino-capped TiO2 nanoparticles were synthesized using tetrabutyl titanate and amino polymers by a two-step sol-gel and hydrothermal method technique for the fabrication of functional cotton fabric. The prepared TiO2 nanoparticles and the treated cotton fabric were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), field emission scanning electron microcopy (FE-SEM) photocatalytic and antibacterial measurement. The results indicate the typical characteristic anatase form of the amino-capped TiO2 NPs with an average crystallite size of 14.9 nm. The treated cotton fabrics exhibit excellent antibacterial property and good photocatalytic degradation of methylene blue.

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