scholarly journals Microstructure, Mössbauer, and Optical Characterizations of Nanocrystalline α-Fe2O3 Synthesized by Chemical Route

ISRN Ceramics ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Abhijit Banerjee ◽  
Soumitra Patra ◽  
Mahuya Chakrabarti ◽  
Dirtha Sanyal ◽  
Mrinal Pal ◽  
...  
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Rietveld Analysis ◽  
Ferromagnetic Behavior ◽  
Chemical Route ◽  
Perfect Lattice ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Type Semiconductor ◽  
Crystallite Sizes

Nanocrystalline α-Fe2O3 of crystallite sizes ranging from 18 nm to 54 nm has been prepared by sol gel process and postannealing the powder up to 500C∘. X-ray diffraction and transmission electron microscopy images have been used for determining the average crystallite sizes of the prepared samples. The Rietveld analysis reveals that the “as-prepared” α-Fe2O3 powders are not completely stoichiometric, and significant (~20%) oxygen vacancies are noticed in the α-Fe2O3 lattice. Oxygen atoms in as-prepared sample are significantly displaced and the lattice is heavily distorted. With increasing annealing temperature the lattice approaches towards the stoichiometric oxygen concentration and perfect lattice configuration. Mössbauer spectrum of the unannealed (as-prepared) α-Fe2O3 sample shows the superparamagnetic behavior at room temperature whereas all annealed samples show complete ferromagnetic behavior. Optical band gaps of these nanocrystalline α-Fe2O3 samples have been measured from UV-Vis spectroscopy and found to decrease from 2.65 eV to 2.50 eV, like an n-type semiconductor, with increasing annealing temperature up to 500C∘.

scholarly journals Synthesis, characterization and in vitro cytotoxicity study of Co and Ni ferrite nanoparticles prepared by sol-gel method

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Alexandre Pancotti ◽  
Dener Pereira Santos ◽  
Dielly Oliveira Morais ◽  
Mauro Vinícius de Barros Souza ◽  
Débora R. Lima ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Test Sample ◽  
In Vitro Cytotoxicity ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Transmission Electron ◽  
Crystallite Sizes

AbstractIn this study, we report the synthesis and characterization of NiFe2O4 and CoFe2O4 nanoparticles (NPs) which are widely used in the biomedical area. There is still limited knowledge how the properties of these materials are influenced by different chemical routes. In this work, we investigated the effect of heat treatment over cytotoxicity of cobalt and niquel ferrites NPs synthesized by sol-gel method. Then the samples were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), Fourier Transform Infrared Spectroscopy Analysis (FTIR), and X-ray fluorescence (XRF). The average crystallite sizes of the particles were found to be in the range of 20–35 nm. The hemocompatibility (erythrocytes and leukocytes) was checked. Cytotoxicity results were similar to those of the control test sample, therefore suggesting hemocompatibility of the tested materials.

scholarly journals Effect of Modified Silica Materials on Polyvinyl Chloride (PVC) Substrates to Obtain Transparent and Hydrophobic Hybrid Coatings

2021 ◽  
Vol 11 (22) ◽  
pp. 11044
Author(s):  
Violeta Purcar ◽  
Valentin Rădițoiu ◽  
Alina Rădițoiu ◽  
Florentina Monica Raduly ◽  
Georgiana Cornelia Ispas ◽  
...  
Keyword(s):  
Polyvinyl Chloride ◽  
Sol Gel ◽  
Contact Angles ◽  
Hybrid Coatings ◽  
Water Contact ◽  
Silica Coatings ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Silica Materials ◽  
Window Blinds

In this research, we report a simple and inexpensive way to prepare transparent and hydrophobic hybrid coatings through deposition of different silica materials on polyvinyl chloride (PVC) substrates. The silica materials were prepared using an acid-catalyzed sol–gel method at room temperature (25 ± 2 °C), using alkoxysilanes: tetraethoxysilane (TEOS), as the silica source, and ethoxydimethylvinylsilane (DMVES), triethoxyoctylsilane (OTES), and trimethoxyhexadecylsilane (HDTMES), as modifier agents. The obtained materials were characterized (either as powders or as thin films) by Fourier-transform infrared spectroscopy (FTIR), UV/Vis spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and water contact-angle measurements. UV/Vis spectra showed that the PVC substrate coated with the silica material containing TEOS/DMVES/OTES had a transmittance of about 90% in the wavelength range of 650–780 nm. The water contact angles increased from 83° for uncoated PVC substrate to ~94° for PVC substrates coated with the sol–gel silica materials. These PVC films with hybrid silica coatings can be used as the materials for outdoor applications, such as energy-generating solar panel window blinds or PVC clear Windmaster outdoor blinds.

CONTROLLED SYNTHESIS AND CHARACTERIZATION OF TiO2 NANOPARTICLES VIA A SOL–GEL METHOD

2004 ◽  
Vol 03 (06) ◽  
pp. 749-755 ◽  
Author(s):  
YING LI ◽  
SUO HON LIM ◽  
TIM WHITE
Keyword(s):  
Sol Gel ◽  
Critical Role ◽  
Rietveld Analysis ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Gelation Temperature ◽  
Gel Method ◽  
Sol Gel Method ◽  
Transmission Electron

The properties influencing the photocatalytic activity of TiO 2 particles have been suggested to include the surface area, crystallinity, crystallite size and crystal structure. Therefore, manipulation of the microstructure of titania, especially of nanocrystalline powders, is very important in the preparative process. In this study, nanocrystalline TiO 2 powders with controlled particle size and phase composition were synthesized at low temperature (<80°C) by a modified sol–gel method. The effects of gelation temperature were systematically investigated. It was found that this parameter played a critical role in determining the crystallinity of single phase anatase. With increasing gelation temperature, the crystallinity of anatase improved initially and then decreased if the temperature was raised to 80°C. These nanomaterials were characterized comprehensively by powder X-ray diffraction (including Rietveld analysis), high-resolution transmission electron microscopy, DSC/TGA thermal analysis and UV–Vis spectrometry.

Ferromagnetism, Raman Spectra and Photoluminescence of Sn0.91Co0.05Ce0.04O2 and Sn0.91Fe0.05Ce0.04O2 Nanorods

2012 ◽  
Vol 488-489 ◽  
pp. 226-229
Author(s):  
Jasneet Kaur ◽  
R.K. Kotnala ◽  
Vinay Gupta ◽  
Kuldeep Chand Verma
Keyword(s):  
Raman Spectroscopy ◽  
Magnetic Measurements ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Stoichiometric Ratio ◽  
Chemical Route ◽  
Structural Modifications ◽  
Co Doping ◽  
Transmission Electron ◽  
20 Nm

In the present work, we have fabricated Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54) nanorods by a chemical route similar to sol-gel method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, photoluminescence (PL) and magnetic measurements are used to characterize these nanorods. XRD pattern shows the polycrystalline nature of rods and TEM confirms that the diameter of rods lie in the range of 15-20 nm and length 100-200 nm. It is observed that on Ce3+ co-doping, nanoparticles assembled themselves into rod like structures. The SCC54 and SFC54 specimens exhibit room temperature ferromagnetism. Their saturated magnetic moment and phase transition temperature is sensitive to their size and stoichiometric ratio. Raman spectroscopy shows an intensity loss of classical cassiterite SnO2 vibration lines, which is indication of significant structural modifications like crystallinity and nano metric size effects on the vibrational properties. From PL spectra, an intense blue luminescence centred at a wavelength of 532 nm is observed in the prepared SnO2 nanostructures, attributed to oxygen-related defects, introduced during the growth process.

Size dependent morphology, magnetic and dielectric properties of BiFeO3 nanoparticles

MRS Advances ◽  
2019 ◽  
Vol 4 (28-29) ◽  
pp. 1659-1665 ◽  
Author(s):  
Nidhi Sheoran ◽  
Monika Saini ◽  
Ashok Kumar ◽  
Vinod Kumar ◽  
Tanuj Kumar ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Phase Formation ◽  
Rural Areas ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Antiferromagnetic Order ◽  
Ferromagnetic Behavior ◽  
Potential Candidate ◽  
Auto Combustion ◽  
Magnetic And Dielectric Properties

AbstractNano-sized BiFeO3 were synthesized by sol-gel auto combustion method and report the effect of different annealing temperature (400 °C, 500 °C, 600 °C) on phase formation, morphology, magnetic and dielectric properties of synthesized bismuth ferrite (BiFeO3) nanoparticles. The phase formation of BFO nanoparticles were confirmed by X-ray diffraction pattern. Further, significant increment in particle size with increasing annealing temperature was estimated by field emission electron microscopy (FESEM). Magnetization curve showed the soft ferromagnetic behavior of the samples annealed at 400 OC and 500 OC that was explained on the basis of disturbance of spiral modulated long range antiferromagnetic order of bulk BFO. Dielectric response revealed decrease in dielectric constant with increasing annealing temperature. BFO is a room-temperature multiferroic material so it is potential candidate for various applications viz. Water waste treatment, gas sensors and photovoltaic cells in rural areas.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

scholarly journals Fabrication of TiO2Nanotanks Embedded in a Nanoporous Alumina Template

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
C. Massard ◽  
S. Pairis ◽  
V. Raspal ◽  
Y. Sibaud ◽  
K. O. Awitor
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
Alumina Template ◽  
Nanoporous Alumina ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Sol Gel Process

The feasibility of surface nanopatterning with TiO2nanotanks embedded in a nanoporous alumina template was investigated. Self-assembled anodized aluminium oxide (AAO) template, in conjunction with sol gel process, was used to fabricate this nanocomposite object. Through hydrolysis and condensation of the titanium alkoxide, an inorganic TiO2gel was moulded within the nanopore cavities of the alumina template. The nanocomposite object underwent two thermal treatments to stabilize and crystallize the TiO2. The morphology of the nanocomposite object was characterized by Field Emission Scanning Electron Microscopy (FESEM). The TiO2nanotanks obtained have cylindrical shapes and are approximately 69 nm in diameter with a tank-to-tank distance of 26 nm. X-ray diffraction analyses performed by Transmission Electron Microscopy (TEM) with selected area electron diffraction (SAED) were used to investigate the TiO2structure. The optical properties were studied using UV-Vis spectroscopy.

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 Structural and Magnetic Properties of Mn Doped BiFeO3 Nanomaterials

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
V. Srinivas ◽  
A. T. Raghavender ◽  
K. Vijaya Kumar
Keyword(s):  
Magnetic Properties ◽  
Doping Concentration ◽  
Structural Changes ◽  
Sol Gel ◽  
Rietveld Analysis ◽  
Ferromagnetic Behavior ◽  
Structural Formation ◽  
Mn Doping ◽  
Structural And Magnetic Properties ◽  
Mn Doped

Nanocrystalline Bi1-xMnxFeO3  (0≤x≤0.3) materials were synthesized using sol-gel technique. The structural and magnetic properties were investigated in detail. Rietveld analysis from XRD revealed the structural formation of BiFeO3. As the Mn doping concentration was increased, the structure of BiFeO3 changed from rhombohedral to tetragonal. All the M-H loops showed the ferromagnetic behavior in the prepared samples. Magnetization was observed to enhance as the Mn doping concentration was increased. The enhanced magnetization may be due to the collapse of the space modulated spin structure as observed from the structural changes.

THE INVESTIGATION ON STABILITY AND STRUCTURAL PROPERTIES OF COHESION-BASED NANOSTRUCTURES MATERIAL

2013 ◽  
Vol 27 (27) ◽  
pp. 1350153 ◽  
Author(s):  
ALI BAHARI ◽  
REZA GHOLIPUR ◽  
MARYAM DERAKHSHI
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Growth Mode ◽  
X Ray Diffraction ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
X Ray ◽  
Annealing Temperatures ◽  
Atomic Force ◽  
Transmission Electron

Styrene-doped ZrLaO y nanostructures were obtained by sol–gel method low-temperature synthesis. The nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and transmission electron microscopy (TEM) techniques. The observation using SEM and TEM revealed that the ring-shaped nanostructures were very uniform. Further characterization using XRD disclosed that the cohesion of the samples was controllable with annealing temperatures in the range of 800–1500°C. Cohesion property was investigated for the samples. The cohesion increased when increasing the annealing temperature. This was linked to the reinforcement of the oxygen bound on the ZrLaO y nanostructures The shape of nanostructures showed a transformation from a ring-shaped growth mode to a hole-surfaced growth mode with increasing annealing temperature. The styrene-doped ZrLaO y nanostructures with controllable crystallinity will have great potential for various applications in fuel, cells, batteries, electronics devices and chemical sensors.

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