scholarly journals Polyol-Made Spinel Ferrite Nanoparticles—Local Structure and Operating Conditions: NiFe2O4 as a Case Study

2021 ◽  
Vol 8 ◽  
Author(s):  
T. Gaudisson ◽  
S. Nowak ◽  
Z. Nehme ◽  
N. Menguy ◽  
N. Yaacoub ◽  
...  
Keyword(s):  
Spinel Phase ◽  
Spinel Ferrite ◽  
Ferrite Nanoparticles ◽  
Operating Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cation Migration ◽  
Anion Vacancies ◽  
Nickel Ferrite Nanoparticles ◽  
Cation And Anion Vacancies

We report the effect of a polyol-mediated annealing on nickel ferrite nanoparticles. By combining X-ray fluorescence spectroscopy, X-ray diffraction, and 57Fe Mössbauer spectrometry, we showed that whereas the as-prepared nanoparticles (NFO) are stoichiometric, the annealed ones (a-NFO) are not, since Ni0-based crystals precipitate. Nickel depletion from the spinel lattice and reduction in the polyol solvent are accompanied with an important cation migration. Indeed, thanks to Mössbauer hyperfine structure analysis, we evidenced that the cation distribution in NFO departs from the thermodynamically stable inverse spinel structure with a concentration of tetrahedrally coordinated Ni2+ of 20 wt-% (A sites). After annealing, and nickel demixing, originated very probably from the A sites of NFO lattice, the spinel phase accommodates with cation and anion vacancies, leading to the (Fe3+0.84□0.16)A[Ni2+0.80Fe3+1.16□0.04]BO4-0.20 formula, meaning that the applied polyol-mediated treatment is not so trivial.

scholarly journals Fabrication of H2S gas sensors using ZnxCu1-xFe2O4 nanoparticles

2020 ◽  
Vol 126 (7) ◽  
Author(s):  
Mohammad Abu Haija ◽  
Mariem Chamakh ◽  
Israa Othman ◽  
Fawzi Banat ◽  
Ahmad I. Ayesh
Keyword(s):  
Gas Sensors ◽  
Spinel Ferrite ◽  
Sol Gel ◽  
Ferrite Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion ◽  
Multiple Cycles ◽  
Cubic Structure ◽  
Combustion Technique

Abstract Spinel ferrite nanoparticles can be easily retrieved and utilized for multiple cycles due to their magnetic properties. In this work, nanoparticles of a ZnxCu1-xFe2O4 composition were synthesized by employing a sol–gel auto-combustion technique. The morphology, composition, and crystal structure were examined using scanning electron microscopy, infrared spectroscopy, and X-ray diffraction. The produced nanoparticles are in the range of 30–70 nm and manifest spinel cubic structure. The nanoparticles were tested for their sensitivity to H2 and H2S gases, and the Cu-based spinel ferrite nanoparticles were found the most sensitive and selective to H2S gas. Their enhanced response to H2S gas was attributed to the production of metallic CuFeS2 that manifest higher electrical conductivity as compared with CuFe2O4. The fabricated sensors are functional at low temperatures, and consequently, they need low operational power. They are also simple to fabricate with appropriate cost.

scholarly journals Thermolysis of sprayed suspensions for obtaining highly spinel ferrite nanoparticles

2019 ◽  
pp. 14-21
Author(s):  
Elena G. Petrova ◽  
Yana A. Shavshukova ◽  
Dzmitry A. Kotsikau ◽  
Kazimir I. Yanushkevich ◽  
Konstantin V. Laznev ◽  
...  
Keyword(s):  
Annealing Temperature ◽  
Spinel Ferrite ◽  
Ferrite Nanoparticles ◽  
Specific Magnetization ◽  
X Ray Diffraction ◽  
Crystallinity Degree ◽  
Insulating Layer ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After

Thermal treatment of ferrite magnetic nanoparticles in NaCl matrix gives an opportunity to increase their specific magnetization with preservation of nanoscale size. Composite materials based on mixed ferrites Co0.65Zn0.35Fe2O4 and Mg 0.5Zn0.5Fe2O4 were synthesized by spray-drying of aqueous suspensions in presence of NaCl and annealed at 300 –900 °C. The microstructure and phase composition of nanoparticles before and after annealing were studied by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction analysis and IR spectroscopy. The magnetic properties of nanoparticles were estimated using a ponderomotive method of measuring the specific magneti zation at room temperature in a magnetic field with an induction of 0.86 T. The increase of the annealing temperature up to 900 °C was established to lead to the increase in the specific magnetization of ferrites – from 32.79 to 91.3 emu/g (Co0.65Zn0.35Fe2O4) and from 2.76 to 22.31 emu/g (Mg 0.5 Zn 0.5Fe2O4) due to recrystallization processes and increase of crystallinity degree of the ferrites. Due to the NaCl insulating layer, the particle size increases just slightly (from ~ 10 nm before annealing to ~ 60 nm after annealing at 900 °C). This method is effective for substantial increase in specific magnetization of ferrite nanoparticles with preservation of their nanoscale size.

Magnetic Study of Nanoferritas CoFe2O4 Obtained by Reaction of Combustion

2014 ◽  
Vol 798-799 ◽  
pp. 402-406
Author(s):  
Polyana Tarciana Araújo Santos ◽  
Pascally M.A. Guerra de Araújo ◽  
Ana Cristina Figueiredo de Melo Costa ◽  
Daniel R. Cornejo
Keyword(s):  
Magnetic Properties ◽  
Infrared Spectroscopy ◽  
High Intensity ◽  
Magnetic Measurements ◽  
Spinel Ferrite ◽  
Magnetic Behavior ◽  
Ferrite Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Peaks

The present work aims to study the magnetic properties of nanoferrita cobalt obtained by combustion reaction. The structural feature as well as the magnetic behavior when in the presence of a magnet and magnetic measurements was investigated. The resulting samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), magnetic behavior when in the presence of a magnet and magnetic measurements. The results indicated the phase single the spinel ferrite CoFe2O4, with high intensity of diffraction peaks indicating that the samples are crystalline and nanoparticle formation. The characteristic bands of spinel were observed for nanoferritas CoFe2O4. The ferrite nanoparticles were strongly attracted when in presence the magnet presenting a saturation magnetization of 58.0 emu/g, coercivity of 1.14 kOe.

Evaluation of cation migration in lanthanum strontium cobalt ferrite solid oxide fuel cell cathodes via in-operando X-ray diffraction

2018 ◽  
Vol 6 (4) ◽  
pp. 1787-1801 ◽  
Author(s):  
J. S. Hardy ◽  
C. A. Coyle ◽  
J. F. Bonnett ◽  
J. W. Templeton ◽  
N. L. Canfield ◽  
...  
Keyword(s):  
Cobalt Ferrite ◽  
Operating Conditions ◽  
Nodule Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lanthanum Strontium ◽  
Cation Migration ◽  
Fuel Cell Cathodes ◽  
In Operando ◽  
Cell Cathodes

SEM and in-operando XRD correlate operating conditions, spinel peak shifts, nano-nodule formation, and activation or degradation behavior in LSCF cathodes.

Structural and Magnetic Properties of Co0.5Ni0.5-xMnxFe2O4(x=0, 0.15, 0.25, 0.35, 0.5) Ferrite Nanoparticles Prepared via Sol-Gel Auto-Combustion Method

2014 ◽  
Vol 3 (3) ◽  
pp. 267-277 ◽  
Author(s):  
Ahmad Amirabadizadeh ◽  
Mohammad Rasouli ◽  
Reza Sarhaddi
Keyword(s):  
Spinel Phase ◽  
Sol Gel ◽  
Combustion Method ◽  
Ferrite Nanoparticles ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Auto Combustion ◽  
Good Agreement

In this study, Co0.5Ni0.5-xMnxFe2O4 (x=0, 0.15, 0.25, 0.35, 0.5) ferrite nanoparticles were prepared by sol-gel auto-combustion method. Structural, magnetic and morphology properties of obtained nanoparticles were investigated with X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Transmission Electron Microscopy(TEM), respectively. The XRD results show that the most dominant peaks for samples is related to the Spinel phase. Crystalline size using Scherrer's equation for different values of x were obtained between 44 to 64 nm. VSM results showed that the saturation magnetization and coercivity values changed with increasing Mn. TEM images obtained results are in good agreement with the XRD results.

scholarly journals Adsorption and gas sensing properties of CuFe2O4 nanoparticles

2019 ◽  
Vol 37 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Mohammad Abu Haija ◽  
Georgia Basina ◽  
Fawzi Banat ◽  
Ahmad I. Ayesh
Keyword(s):  
Gas Sensors ◽  
Gas Sensing ◽  
Spinel Ferrite ◽  
Ferrite Nanoparticles ◽  
Grid Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sensing Applications ◽  
Transmission Electron ◽  
Gas Sensing Properties

AbstractSpinel ferrite nanoparticles in the form CuFe2O4 were tested for gas sensing applications. Nanoparticles pressed in a disk form were used to construct conductometric gas sensors. The disk was placed between two electrical electrodes wherein the top electrode had a grid structure. The produced sensors were tested against H2S and H2 gases and they were found to be selective and sensitive to H2S concentration as low as 25 ppm. The composition of the nanoparticles was confirmed by X-ray diffraction and energy dispersive X-ray spectroscopy measurements. The crystal structure was verified by both X-ray diffraction and transmission electron microscope. The observations obtained from the experiments demonstrated the high potential of using CuFe2O4 nanoparticles for H2S sensing applications.

scholarly journals Multi-Scale Studies of 3D Printed Mn–Na–W/SiO2 Catalyst for Oxidative Coupling of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 290
Author(s):  
Tim Karsten ◽  
Vesna Middelkoop ◽  
Dorota Matras ◽  
Antonis Vamvakeros ◽  
Stephen Poulston ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Operating Conditions ◽  
Homogeneous Distribution ◽  
Silica Support ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Multi Scale ◽  
3D Printed

This work presents multi-scale approaches to investigate 3D printed structured Mn–Na–W/SiO2 catalysts used for the oxidative coupling of methane (OCM) reaction. The performance of the 3D printed catalysts has been compared to their conventional analogues, packed beds of pellets and powder. The physicochemical properties of the 3D printed catalysts were investigated using scanning electron microscopy, nitrogen adsorption and X-ray diffraction (XRD). Performance and durability tests of the 3D printed catalysts were conducted in the laboratory and in a miniplant under real reaction conditions. In addition, synchrotron-based X-ray diffraction computed tomography technique (XRD-CT) was employed to obtain cross sectional maps at three different positions selected within the 3D printed catalyst body during the OCM reaction. The maps revealed the evolution of catalyst active phases and silica support on spatial and temporal scales within the interiors of the 3D printed catalyst under operating conditions. These results were accompanied with SEM-EDS analysis that indicated a homogeneous distribution of the active catalyst particles across the silica support.

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

scholarly journals Characterization of ferrite nanoparticles for preparation of biocomposites

2017 ◽  
Vol 8 ◽  
pp. 1257-1265 ◽  
Author(s):  
Urszula Klekotka ◽  
Magdalena Rogowska ◽  
Dariusz Satuła ◽  
Beata Kalska-Szostko
Keyword(s):  
Chemical Method ◽  
Ferrite Nanoparticles ◽  
Chemical Activity ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

Ferrite nanoparticles with nominal composition Me0.5Fe2.5O4 (Me = Co, Fe, Ni or Mn) have been successfully prepared by the wet chemical method. The obtained particles have a mean diameter of 11–16 ± 2 nm and were modified to improve their magnetic properties and chemical activity. The surface of the pristine nanoparticles was functionalized afterwards with –COOH and –NH2 groups to obtain a bioactive layer. To achieve our goal, two different modification approaches were realized. In the first one, glutaraldehyde was attached to the nanoparticles as a linker. In the second one, direct bonding of such nanoparticles with a bioparticle was studied. In subsequent steps, the nanoparticles were immobilized with enzymes such as albumin, glucose oxidase, lipase and trypsin as a test bioparticles. The characterization of the nanoparticles was acheived by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and Mössbauer spectroscopy. The effect of the obtained biocomposites was monitored by Fourier transform infrared spectroscopy. The obtained results show that in some cases the use of glutaraldehyde was crucial (albumin).

Sign in / Sign up

Export Citation Format

Share Document