synthesis temperature
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2022 ◽  
Author(s):  
Hamid Hosseinzadeh ◽  
Hamidreza Oveisi

Abstract In the present study, CoFe2O4 and CoFe2-xGdxO4 nanoparticles were synthesized by the hydrothermal process. The CoFe2O4 nanoparticles were synthesized at different temperatures (70oC, 100oC, 150oC, and 200oC), molar ratio of CoCl2/ FeCl3 (0/2, 0.75/2, 1/2, 1.5/2, and 2/2). Gadolinium-doped cobalt ferrite (CoFe2-xGdxO4) nanoparticles have also been synthesized with Gd/Fe molar ratios of 0.18 and 0.53. The XRD patterns indicate that cobalt ferrite and Gadolinium-doped cobalt ferrite nanoparticles have been successfully synthesized without impurities with a medium degree of crystallinity. The XRD patterns show that by increasing the synthesis temperature from 70oC to 200oC, the size of the nanoparticles decreased from 50.49nm to 32.45nm while the morphology of the nanoparticles also changed from a shapeless and agglomerated state to a spherical shape. The XPS curve illustrated several peaks corresponding to Fe+3, Co+2, and O 1s. The binding energies for Co and Fe were consistent with Fe 2p and Co 2p binding energies for cobalt ferrite nanoparticles. The magnetic saturation value (Ms) increased from 17.253 emu/g to 54.438 emu/g with a rise in the synthesis temperature. The effects of FeCl3/CoCl2 molar ratio on the magnetic properties showed the highest value of Ms (54.438 emu/g) and the coercivity (HC) of 744.56 Oe for a 2/1 molar ratio. The addition of gadolinium to the composition resulted in a reducing of the magnetic properties of nanoparticles; accordingly, the amount of saturated magnetization was reduced to 22.469 emu/g. Another effect of gadolinium dopant in the composition was a change in nanoparticle morphology from spherical to rod shape. The final aim of this study was to investigate the possible utilization of CoFe2O4 and CoFe2-xGdxO4 nanoparticles in medical treatment in the near future.


Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 136
Author(s):  
Nikolay P. Simonenko ◽  
Andrey G. Musaev ◽  
Tatiana L. Simonenko ◽  
Philipp Yu. Gorobtsov ◽  
Ivan A. Volkov ◽  
...  

In this article, a facile, one-step method for the formation of silver thin-film nanostructures on the surface of Al2O3 substrates using the hydrothermal method is proposed. The dependence of the SERS effect intensity of the formed films during the detection of methylene blue (MB) low concentrations on the synthesis conditions, additional temperature treatment, and laser radiation wavelength (532 and 780 nm) in comparison with similar dye films on commercial SERS substrates is shown. The detection limit of the analyte used for the indicated lasers is estimated. The effect of the synthesis temperature on the particle size, crystal structure, and microstructure features of the obtained thin films based on silver nanoparticles is demonstrated. Using spreading resistance microscopy, the interface between the substrate and Ag particles is studied, and the dependence of the size of the corresponding gap between them and the nature of microstructural defects on the parameters of hydrothermal treatment of reaction systems in the presence of Al2O3 substrates is shown. As a result of the study, the factors associated with the properties of the obtained SERS substrates and the parameters of recording the spectra, which affect the amplification factor of the spectral lines intensity of the analyte, are revealed.


2021 ◽  
Vol 223 (1) ◽  
pp. 162-172
Author(s):  
Narit Triamnak ◽  
Natthapong Wongdamnern ◽  
Thanapong Sareein ◽  
Athipong Ngamjarurojana ◽  
Rattikorn Yimnirun

2021 ◽  
Vol 11 (1) ◽  
pp. 136-144
Author(s):  
Yangjie Han ◽  
Renwang Yu ◽  
Honghua Liu ◽  
Yanhui Chu

AbstractThe high-purity and superfine high-entropy zirconate nanopowders, namely (Y0.25La0.25Sm0.25Eu0.25)2Zr2O7 nanopowders, without agglomeration, were successfully synthesized via polymerized complex method at low temperatures for the first time. The results showed that the crystallinity degree, lattice strain, and particle size of the as-synthesized powders were gradually enhanced with the increase of the synthesis temperature from 800 to 1300 °C. The as-synthesized powders involved fluorite phase in the range of 800–1200 °C while they underwent the phase evolution from fluorite to pyrochlore at 1300 °C. It is worth mentioning that the as-synthesized powders at 900 °C are of the highest quality among all the as-synthesized powders, which is due to the fact that they not only possess the particle size of 11 nm without agglomeration, but also show high purity and good compositional uniformity.


Author(s):  
Volodymyr Oleksiyovych Chyshkala ◽  
Serhii Volodymyrovych Lytovchenko ◽  
Edwin Spartakovych Gevorkyan ◽  
Volodymyr Pavlovych Nerubatskyi ◽  
Bogdan Оlexandrovych Mazilin ◽  
...  

Modern scientific and technological development of society, further intensification of production together with the provision of proper safety of human life and preservation of the environment necessitate the search for new solutions in the creation of new materials and technologies. The creation of effective materials for the latest and future technologies and technicaldevices is based on new scientific data on the definition and analysis of specific mechanisms of physicochemical processes that implement the desired structural and phase state of solids with the desired set of properties. In recent decades, the most effective way to control the properties of solid materials is the use of nanotechnology and nanomaterials, which have recently been increasingly used in almost all areas of new technologies. The article investigates synthesis processes, structural characteristics and structural-phase processes in multicomponent metal-ceramic oxide materials, physicochemical mechanisms ofsynthesi s of multielement oxide compounds Y2Zr2O7 with pyrochlor structure during consolidation and sintering of yttrium and zirconium oxides, structure formation -phase characteristics of materials with different chemical composition. The structural-phase evolution in the synthesis of new substances and the consolidation of compounds of the Y2O3 – ZrO2 system have been studied. Samples of oxide heat with the proportion of pyrochlorine phase Y2Zr2O7 up to 41 % were obtained. It is established that the kinetics of increasing the proportion of pyrochlorine phase in the samples indicates a desirable increase in the activity of the chemical reaction, which can be achieved by increasing the synthesis temperature to the temperatures of eutectic formation or increasing the reaction surface of powders.


2021 ◽  
Author(s):  
Demet Dağıdır ◽  
Nil Acaralı

Abstract In this study, experiments were carried out for composite membrane synthesis with m-phenylenediamine (MPD), hydroxyethyl methacrylate (HEMA) and methyl cellulose (MS) by changing process parameters (methyl cellulose ratio, synthesis temperature, stirring time, oven temperature). Taguchi Method, an optimization method for production, was applied to 4 levels 4 parameters. The silica solution was passed through the produced composite membrane, and the filtering property of the membrane for different periods was examined. Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) were used for characterization of composite membranes. Shore A test was performed to determine the mechanical strength of composite membranes. The amount of silica in membranes obtained because of the silica treatment was determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis. As a result, it was seen that the composite membranes produced could be evaluated in the treatment of wastewater containing silica.


Author(s):  
Jie Li ◽  
Qing-Hao Yang ◽  
Hsin-Hua Li ◽  
Cheng-Fu Yang ◽  
David Jui-Yang Feng

First, a solid-state reaction method was used to synthesize a [Formula: see text] phosphor at 1250[Formula: see text]C–1400[Formula: see text]C for 1 h, and its crystal structures and photoluminescence properties were investigated as a function of synthesis temperature. When the furnace reached the synthesis temperature, the 5% [Formula: see text] reduction atmosphere was infused and the reduction atmosphere was removed as the temperature was dropped to 800[Formula: see text]C. When 1200[Formula: see text]C was used as the synthesis temperature, the [Formula: see text], [Formula: see text], and [Formula: see text] phases co-existed; only one weak emission peak was observed in the photoluminescence excitation (PLE) spectra, and two weak emission peaks were observed in the photoluminescence emission (PL) spectra. When the [Formula: see text] phosphors were synthesized at a temperature higher than 1200[Formula: see text]C, the diffraction intensities of [Formula: see text], [Formula: see text], and [Formula: see text] phases were almost unchanged, but the crystal sizes of [Formula: see text] powders increased. For [Formula: see text] phosphors, PLE spectra had one broad exciting band with two centered wavelengths of 317 and 365 nm, and PL spectra had one emission band with one centered wavelength of 513 nm. As the synthesis temperature rose, the emission intensities of PLE and PL spectra increased. Second, we show that the removed temperature of reduction atmosphere of [Formula: see text] phosphors had an apparent effect on their emission properties of PLE and PL spectra.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3369
Author(s):  
Stefanos Mourdikoudis ◽  
George Antonaropoulos ◽  
Nikolas Antonatos ◽  
Marcos Rosado ◽  
Liudmyla Storozhuk ◽  
...  

Copper selenide-sulfide nanostructures were synthesized using metal-organic chemical routes in the presence of Cu- and Se-precursors as well as S-containing compounds. Our goal was first to examine if the initial Cu/Se 1:1 molar proportion in the starting reagents would always lead to equiatomic composition in the final product, depending on other synthesis parameters which affect the reagents reactivity. Such reaction conditions were the types of precursors, surfactants and other reagents, as well as the synthesis temperature. The use of ‘hot-injection’ processes was avoided, focusing on ‘non-injection’ ones; that is, only heat-up protocols were employed, which have the advantage of simple operation and scalability. All reagents were mixed at room temperature followed by further heating to a selected high temperature. It was found that for samples with particles of bigger size and anisotropic shape the CuSe composition was favored, whereas particles with smaller size and spherical shape possessed a Cu2−xSe phase, especially when no sulfur was present. Apart from elemental Se, Al2Se3 was used as an efficient selenium source for the first time for the acquisition of copper selenide nanostructures. The use of dodecanethiol in the presence of trioctylphosphine and elemental Se promoted the incorporation of sulfur in the materials crystal lattice, leading to Cu-Se-S compositions. A variety of techniques were used to characterize the formed nanomaterials such as XRD, TEM, HRTEM, STEM-EDX, AFM and UV-Vis-NIR. Promising results, especially for thin anisotropic nanoplates for use as electrocatalysts in nitrogen reduction reaction (NRR), were obtained.


2021 ◽  
Author(s):  
Sushobhita Chawla ◽  
Garima Aggarwal ◽  
Akash Kumar ◽  
Akhilender Jeet Singh ◽  
Dr. Balasubramaniam Kavaipatti

Lowering the synthesis temperature to obtain phase pure BaSnO3, which is the host material for high figure-of-merit (FOM) perovskite transparent conductors (TCs), can expand the horizons for its optoelectronic applications, with an obvious reduction in the thermal budget. In this work, we have developed a novel solution combustion technique for the synthesis of BaSnO3 nanoparticles. A peroxo/superoxo precursor to the nanoparticles is first synthesized by co-precipitation of the tin and barium salts via the H2O2 assisted or the `CSMC' route. The phase evolution, under different drying conditions of the wet precursor to crystalline BaSnO3 nanoparticles is then studied. We find that the crystallization temperature of BaSnO3 is significantly reduced by adding an organic solvent such as ethanol or propanol to the precursor; temperatures as low as 130 °C yield phase pure BaSnO3 nanoparticles. We establish that the organic solvent increases the reactive O2 ligand content, which plays a pivotal role in the synthesis. Due to this, an exothermic reaction occurs around 130 °C, thereby providing the heat of reaction for conversion of the precursor to phase-pure BaSnO3. Importantly, this method should also allow for the facile incorporation of dopants, paving the way for synthesis of high FOM TCs at low temperatures. Such low synthesis temperatures enable BaSnO3 to be used in devices having temperature limitations during device processing, such as heterojunction Si solar cells or perovskite-based solar cells in an n-i-p architecture.


2021 ◽  
Vol 2119 (1) ◽  
pp. 012121
Author(s):  
I E Merkulova

Abstract The thin polycrystalline aluminium films were synthesized on monocrystalline silicon substrates by ion-plasma sputtering. The synthesis was carried out at temperatures of 80 and 160°C and deposition rate of 10 and 110 nm/min. As-deposited films were annealed for 15 h at 550°C. The morphology of aluminium films before and after annealing was obtained using SEM images. The surfaces of as-deposited Al thin films, synthesized at high temperature, were uneven, while for low temperature films they were smooth enough with Al hillocks on the top of the film. After thermal annealing, morphology of the films was changed slightly. XRD patterns were obtained to calculate the average Al grain size of as-deposited and annealed films. The XRD analysis showed that an increase in the synthesis temperature leads to an increase in the average grain size from 50 to 84 nm and that increase in the rate of Al film synthesis leads to an increase in the average grain size from 50 to 63 nm. As the result of annealing, the average grain size increased for all samples and the final meaning was from 78 to 140 nm.


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