scholarly journals The Influence of Co-Precipitation Technique on the Structure, Morphology and Dual-Modal Proton Relaxivity of GdFeO3 Nanoparticles

Inorganics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 39
Author(s):  
Yamen Albadi ◽  
Maria S. Ivanova ◽  
Leonid Y. Grunin ◽  
Kirill D. Martinson ◽  
Maria I. Chebanenko ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Relaxation Times ◽  
Average Crystallite Size ◽  
Nitrogen Adsorption ◽  
Mri Contrast Agents ◽  
Colloidal Solutions ◽  
Characteristic Particle ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
Average Size

Nanocrystals of gadolinium orthoferrite (GdFeO3) with morphology close to isometric and superparamagnetic behavior were successfully synthesized using direct, reverse and microreactor co-precipitation of gadolinium and iron(III) hydroxides with their subsequent heat treatment in the air. The obtained samples were investigated by PXRD, FTIR, low-temperature nitrogen adsorption-desorption measurements, HRTEM, SAED, DRS and vibration magnetometry. According to the X-ray diffraction patterns, the GdFeO3 nanocrystals obtained using direct co-precipitation have the smallest average size, while the GdFeO3 nanocrystals obtained using reverse and microreactor co-precipitation have approximately the same average size. It was shown that the characteristic particle size values are much larger than the corresponding values of the average crystallite size, which indicates the aggregation of the obtained GdFeO3 nanocrystals. The GdFeO3 nanocrystals obtained using direct co-precipitation aggregate more than the GdFeO3 nanocrystals obtained using reverse co-precipitation, which, in turn, tend to aggregate more strongly than the GdFeO3 nanocrystals obtained using microreactor co-precipitation. The bandgap of the obtained GdFeO3 nanocrystals decreases with decreasing crystallite size, which is apparently due to their aggregation. The colloidal solutions of the obtained GdFeO3 nanocrystals with different concentrations were investigated by 1H NMR to measure the T1 and T2 relaxation times. Based on the obtained r2/r1 ratios, the GdFeO3 nanocrystals obtained using microreactor, direct and reverse co-precipitation may be classified as T1, T2 and T1–T2 dual-modal MRI contrast agents, respectively.

Cobalt Metal ion Doped Cerium Oxide (Co-CeO2) Nanoparticles Effect Enhanced Photocatalytic Activity

MRS Advances ◽  
2020 ◽  
pp. 1-13
Author(s):  
G. Killivalavan ◽  
B. Sathyaseelan ◽  
G. Kavitha ◽  
I. Baskarann ◽  
K. Senthilnathan ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Metal Ion ◽  
Chemical Properties ◽  
Visible Spectrum ◽  
Average Crystallite Size ◽  
Cobalt Metal ◽  
Uv Visible ◽  
Co Precipitation ◽  
Average Size ◽  
Physical And Chemical

Abstract The REE (rare-earth-elements) cerium (Ce) is the most abundant earth-crust element and their oxides have great attention in the form of nanocrystalline nature with superior physical and chemical properties. Pure and Co (1%, 3% and 5%) doped CeO2 nanoparticles (NPs) synthesized by co-precipitation technique were characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy. XRD shows face-centred-cubic (FCC) crystal symmetry with average crystallite size 6–12 nm. HRTEM exhibits almost identical cubical shaped particles with average size 4–10 nm. Tuned band-gap may be observed from UV-visible spectrum of CeO2-NPs upon Co (1%, 3% & 5%) incorporation. Enhancement of the photocatalytic activity observed for Co-doped (1%, 3% & 5%) to the degradation of methylene-blue (MB) dye under visible-light absorption.

High-Energy Ball Milling Conditions in Formation of NiTiCu Shape Memory Alloys

2021 ◽  
pp. 1-7
Author(s):  
Tomasz Goryczka ◽  
Piotr Salwa ◽  
Maciej Zubko
Keyword(s):  
Chemical Composition ◽  
Shape Memory ◽  
Crystallite Size ◽  
Ball Milling ◽  
Average Crystallite Size ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Energy Ball ◽  
Average Size ◽  
Grinding Time

The properties and the shape memory effect depend, among other things, on chemical composition, as well as the method of shape memory alloy (SMA) production. One of the manufacturing methods that leads to the amorphous/nanocrystalline SMA is high-energy ball milling combined with annealing. Using this technique, an SMA memory alloy, with the nominal chemical composition of Ni25Ti50Cu25, was produced from commercial elemental powders (purity −99.7%). The structure and morphology were characterized (at the various stages of its production) by the use of X-ray diffraction, as well as electron microscopy (both scanning and transmission). Choosing the appropriate grinding time made it possible to produce an NiTiCu alloy with a different crystallite size. Its average size changed from 6.5 nm (after 50 h) to about 2 nm (100 h). Increasing the grinding time up to 140 h resulted in the formation of areas that showed the B19 martensite and the Ti2(Ni,Cu) phase with the average crystallite size of about 6 nm (as milled). After crystallization, the average size increased to 11 nm.

Magnetic and Catalytic Properties of Cu0.5Zn0.5Fe2O4 Nanocrystallite Powders

2006 ◽  
Vol 6 (1) ◽  
pp. 114-119 ◽  
Author(s):  
M. M. Rashad ◽  
M. H. Khedr ◽  
K. S. Abdel-Halim
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Ferrous Sulfate ◽  
Average Crystallite Size ◽  
Sulfate Solution ◽  
Stoichiometric Ratio ◽  
Spent Catalyst ◽  
Hydrothermal Temperature ◽  
Iron And Steel ◽  
Average Size

Cu0.5Zn0.5Fe2O4 nanocrystallite powders (average size 13 nm) were synthesized from Cu–Zn spent catalyst (fertilizers) industries and ferrous sulfate wastes formed during iron and steel making. Cu–Zn catalyst (22.4% Cu and 26.4% Zn) was chemically treated with sulfuric acid at temperature 80 °C for 1 hr for the complete dissolving of copper and zinc into sulfate solution, then the produced solution was mixed with stoichiometric ratio of ferrous sulfate and the mixture was chemically precipitated as hydroxides followed by hydrothermal processing. The parameters affecting the magnetic properties and crystallite size of the produced ferrites powder e.g., temperature, time, and pH were systemically studied. X-ray diffraction analysis was used in order to determine the average crystallite size and phase identifications of the produced powder. The magnetic properties were studied by vibrating sample magnetometry. The results showed that the average crystallite size of the powder decreased for the ferrites powder formed at 150 °C and then increased by increasing the temperature to 200 °C. Interestingly, the saturation magnetization (Bs), remanent magnetization (Br) and coercive force (Hc) were 25.03 emu/g, 0.71 emu/g, and 4.83 Oe, respectively at hydrothermal temperature 150 °C for 24 hr and changed to 16.38 emu/g, 0.3864 emu/g, and 5.2 Oe at 150 °C and 72 hr. The produced nanoferrite powders are used for studying the catalytic activity of CO conversion to CO2 at different temperatures, pH and times. The maximum conversion (82%) is obtained at temperature 150 °C for 24 hrs and pH 12.

scholarly journals Synthesis and Characterization of Pure and Rare-Earth Metal Gd Doped SnO2-CuO Nanoparticles by Co-Precipitation Method

2018 ◽  
Vol 4 (5) ◽  
pp. 478-482
Author(s):  
L. Prakash ◽  
C. Tirupathi
Keyword(s):  
Rare Earth ◽  
Band Gap ◽  
Crystallite Size ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Average Crystallite Size ◽  
Cuo Nanoparticles ◽  
Precipitation Method ◽  
Pure Sno2 ◽  
Co Precipitation

Pure and rare-earth metal Gd doped SnO2-CuO nanoparticles were successfully prepared from the starting materials SnCl2, CuCl2 and doping element gadolinium nitrate. Pure and Gd doped SnO2-CuO were synthesized by co-precipitation method. The samples were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), UV-Vis, SEM, EDX and dielectric studies. The XRD analysis reveals that the rare-earth metal Gd dopants were substituted into rutile SnO2-CuO nanoparticles. Pure SnO2-CuO nanoparticles have an average crystallite size of 15 nm and rare-earth metal Gd doped SnO2-CuO nanoparticles have 18 nm. The average crystallite size of the sample increases when dopant was used and XRD peak intensity also increases when compared to pure SnO2-CuO nanoparticles. The optical absorption measurements exposed the nanometric size of the materials influences the energy band gap. Optical band gap was found to be 5.08 eV for pure SnO2-CuO nanoparticles and 5.14 eV for Gd doped SnO2-CuO nanoparticles. Surface morphology of pure and Gd doped SnO2-CuO nanoparticles annealed at 400 °C shows that most of the particles are rod shaped and hence it may have better sensitivity. Dielectric constant and dielectric loss decrease with increasing frequency at 100 °C and 200 °C. Doped samples show larger dielectric properties than pure SnO2-CuO nanoparticles.

scholarly journals Ga2O3(Sn) Oxides for High-Temperature Gas Sensors

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2938
Author(s):  
Nataliya Vorobyeva ◽  
Marina Rumyantseva ◽  
Vadim Platonov ◽  
Darya Filatova ◽  
Artem Chizhov ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Sensors ◽  
Photoelectron Spectroscopy ◽  
Average Crystallite Size ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
X Ray ◽  
Adsorption Sites ◽  
Co Precipitation ◽  
High Temperature Gas

Gallium(III) oxide is a promising functional wide-gap semiconductor for high temperature gas sensors of the resistive type. Doping of Ga2O3 with tin improves material conductivity and leads to the complicated influence on phase content, microstructure, adsorption sites, donor centers and, as a result, gas sensor properties. In this work, Ga2O3 and Ga2O3(Sn) samples with tin content of 0–13 at.% prepared by aqueous co-precipitation method were investigated by X-ray diffraction, nitrogen adsorption isotherms, X-ray photoelectron spectroscopy, infrared spectroscopy and probe molecule techniques. The introduction of tin leads to a decrease in the average crystallite size, increase in the temperature of β-Ga2O3 formation. The sensor responses of all Ga2O3(Sn) samples to CO and NH3 have non-monotonous character depending on Sn content due to the following factors: the formation of donor centers and the change of free electron concentration, increase in reactive chemisorbed oxygen ions concentration, formation of metastable Ga2O3 phases and segregation of SnO2 on the surface of Ga2O3(Sn) grains.

scholarly journals Adsorption of Congo Red on Pb doped FexOy: experimental study and theoretical modeling via double-layer statistical physics models

2021 ◽  
Author(s):  
Umesh Fegade ◽  
Sachin Kolate ◽  
Rajesh Dhake ◽  
Inamuddin ◽  
Tariq A. Altalhi ◽  
...  
Keyword(s):  
Double Layer ◽  
Congo Red ◽  
Statistical Physics ◽  
Average Crystallite Size ◽  
Precipitation Method ◽  
Isotherm Models ◽  
Double Layer Model ◽  
Physics Model ◽  
Co Precipitation ◽  
Average Size

Abstract Size-controlled Pb0.06Fe0.7O3 nanoparticles (Pb-FeONPs) werefabricated by the thermal co-precipitation method and characterized by FE-SEM, EDX, XRD, and IR techniques. The SEM and XRD images showed the average size distribution and average crystallite size of 19.21 nm and 4.9 nm, respectively. The kinetic model of congo red (CR) adsorption onto Pb-FeONPs was verified and found to bea pseudo-second-order reaction. The Langmuir plot best fitted (R2 = 0.990) than other isotherm models with a Qmax (mg/g) of 500 for congo red (CR) dye in 40 min. The double-layer statistical physics model based on two energies was used to calculate the significant parameters. The n (Stoichiometric coefficient) values obtained from the statistical physics double-layer model were found to be 0.599, 0.593, and 0.565 which are less than 1, indicating the multi-docking process. The regeneration of Pb-FeONPs was used upto 5 cycles effectively, making the material highly economical. The Pb-FeONPs were fruitfully applied for the removal of CR dye from wastewater on a laboratory and industrial scale.

scholarly journals Influence of Milling Time on Structural and Microstructural Parameters of Ni50Ti50 Prepared by Mechanical Alloying Using Rietveld Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
E. Sakher ◽  
N. Loudjani ◽  
M. Benchiheub ◽  
M. Bououdina
Keyword(s):  
Mechanical Alloying ◽  
Crystallite Size ◽  
Amorphous Phase ◽  
Milling Time ◽  
Stacking Faults ◽  
Average Crystallite Size ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Microstructural Parameters ◽  
Diffraction Patterns

Nanostructured Ni50Ti50 powders were prepared by mechanical alloying from elemental Ni and Ti micrometer-sized powders, using a planetary ball mill type Fritsch Pulverisette 7. In this study, the effect of milling time on the evolution of structural and microstructural parameters is investigated. Through Rietveld refinements of X-ray diffraction patterns, phase composition and structural/microstructural parameters such as lattice parameters, average crystallite size L, microstrain ε21/2, and stacking faults probability (SFP) in the frame of MAUD software have been obtained. For prolonged milling time, a mixture of amorphous phase, NiTi-martensite (B19′), and NiTi-austenite (B2) phases, in addition to FCC-Ni(Ti) and HCP-Ti(Ni) solid solutions, is formed. The crystallite size decreases to the nanometer scale while the internal strain increases. It is observed that, for longer milling time, plastic deformations introduce a large amount of stacking faults in HCP-Ti(Ni) rather than in FCC-Ni(Ti), which are mainly responsible for the observed large amount of the amorphous phase.

Identification by Electron Microdiffraction of Intermetallic Phases in a Duplex Stainless Steel

1990 ◽  
Vol 48 (2) ◽  
pp. 494-495
Author(s):  
A. Redjaïmia ◽  
J.P. Morniroli ◽  
G. Metauer ◽  
M. Gantois
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Convergent Beam Electron Diffraction ◽  
Intermetallic Phases ◽  
Small Particles ◽  
Parallel Beam ◽  
Diffraction Patterns ◽  
Average Size ◽  
Convergent Beam ◽  
Electron Microdiffraction

2D and especially 3D symmetry information required to determine the crystal structure of four intermetallic phases present as small particles (average size in the range 100-500nm) in a Fe.22Cr.5Ni.3Mo.0.03C duplex stainless steel is not present in most Convergent Beam Electron Diffraction (CBED) patterns. Nevertheless it is possible to deduce many crystal features and to identify unambiguously these four phases by means of microdiffraction patterns obtained with a nearly parallel beam focused on a very small area (50-100nm).From examinations of the whole pattern reduced (RS) and full (FS) symmetries the 7 crystal systems and the 11 Laue classes are distinguished without ambiguity (1). By considering the shifts and the periodicity differences between the ZOLZ and FOLZ reflection nets on specific Zone Axis Patterns (ZAP) which depend on the crystal system, the centering type of the cell and the glide planes are simultaneously identified (2). This identification is easily done by comparisons with the corresponding simulated diffraction patterns.

scholarly journals Upconversion Luminescence of Silica–Calcia Nanoparticles Co-doped with Tm3+ and Yb3+ Ions

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Katarzyna Halubek-Gluchowska ◽  
Damian Szymański ◽  
Thi Ngoc Lam Tran ◽  
Maurizio Ferrari ◽  
Anna Lukowiak
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Upconversion Luminescence ◽  
Sol Gel ◽  
Emission Spectra ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
Diffraction Patterns ◽  
Size Of Particles ◽  
Average Size

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

Sign in / Sign up

Export Citation Format

Share Document