Syntheses of Hematite (α-Fe2O3) Nanoparticles Using Microwave-Assisted Calcination Method

2013 ◽  
Vol 737 ◽  
pp. 197-203 ◽  
Author(s):  
Tati Nurhayati ◽  
Ferry Iskandar ◽  
Khairurrijal ◽  
Abdullah Mikrajuddin
Keyword(s):  
Microwave Heating ◽  
Heating Time ◽  
Average Particle ◽  
Hematite Nanoparticles ◽  
Sem Images ◽  
Calcination Process ◽  
Microwave Assisted ◽  
Crystallite Sizes ◽  
Calcination Method ◽  
Xrd Patterns

Hematite (α-Fe2O3) nanoparticles were synthesized from the solution of FeCl3.6H2O and NaOH in water using microwave-assisted calcination method. The syntheses were initially carried out by microwave heating and completed by a calcination process using a simple heating method. The effect of microwave heating time, calcination temperature, and calcination time were investigated. The XRD patterns demonstrated that the obtained nanoparticles are pure hematite. Using the Scherrer method, the average crystallite sizes of hematite nanoparticles were in the range of 35.6 to 54.4 nm. The obtained hematite nanoparticles were spherical with the average particle sizes ranging from 91 to 116 nm as confirmed by the SEM images.

scholarly journals Microwave Assisted-Hydrothermal Synthesis of Nickel Ferrite Nanoparticles

2018 ◽  
Vol 34 (5) ◽  
pp. 2577-2582
Author(s):  
Mohamed H. H. Mahmoud ◽  
Mahmoud M. Hessien
Keyword(s):  
Nickel Ferrite ◽  
High Performance ◽  
Fine Particles ◽  
Low Cost ◽  
Nickel Chloride ◽  
Heating Time ◽  
Stoichiometric Ratio ◽  
Microwave Assisted ◽  
Xrd Patterns ◽  
Co Precipitation

Nanomagnetic ferrite materials are of great technological importance in several industries due to their high performance, ease of preparation and low cost. The ferrite properties are based on composition, structure and methods of preparation. Nickel ferrite, NiFe2O4, was prepared by the simple microwave assisted-hydrothermal method. Nickel chloride and ferric chloride solutions (stoichiometric ratio of 1: 2 respectively) were mixed, the pH was raised to 10.5 and the mixture was heated at 180 °C in a closed Teflon vessel using a microwave oven at different periods of time (2 - 24 h). The formed powders were examined by XRD, TEM, and VSM. The intensity of nickel-ferrite in the XRD patterns increased with time owing to increase in crystallinity of the formed phase. The TEM images showed that, the size was in the range of 20-40 nm and contents of fine particles noticeably decreased with increasing reaction time to 4-6 hrs and contents of more regular cubic particles are formed. The NiFe2O4 magnetization was continuesly increased with raising the heating time from 2h (9 emu/g) to 24 h (43 emu/g) which may be due to the high purity and crystallinity of the formed NiFe2O4. The results showed that the properties of the formed ferrite can be tailored by controlling the heating time. Microwave assisted co-precipitation followed by hydrothermal digestion resulted in a substance of good homogeneity and crystallinity at a short time.

Synthesis of Fe2O3/C Nanocomposite Using Microwave Assisted Calcination Method

2014 ◽  
Vol 896 ◽  
pp. 100-103 ◽  
Author(s):  
Anggi Puspita Swardhani ◽  
Ferry Iskandar ◽  
Abdullah Mikrajuddin ◽  
Khairurrijal
Keyword(s):  
Crystallite Size ◽  
Average Particle Size ◽  
Molar Ratio ◽  
Average Particle ◽  
X Ray ◽  
Molar Ratios ◽  
Microwave Assisted ◽  
Chloride Hexahydrate ◽  
Calcination Method ◽  
Scherrer Method

Fe2O3/C nanocomposites were successfully synthesized using microwave assisted calcination method. Ferric (III) chloride hexahydrate (FeCl36H2O), sodium hydroxide (NaOH), and dextrose monohydrate (C6H12O6H2O) were used as precursors. A microwave oven of 2.445 GHz with a power of 600 W for 20 minutes was employed during the syntheses. Calcination was performed in a simple furnace at 350 °C for 30 min. The molar ratio of C:Fe is the only process parameter. From Scanning Electron Microscope images, the average particle size were 199 nm and 74 nm for the samples with molar ratio of C:Fe of 1:2 and 1:1, respectively. X-ray diffractometer spectra showed that the obtained samples have γ-Fe2O3 (maghemite) crystal structure. Using the Scherrer method, the crystallite size were 61.7, 58.8, 52.5, and 48.8 nm for the samples with the molar ratios of C:Fe of 1:3, 1:2, 1:1, and 2:1, respectively. It means that the crystallite size of the nanocomposite decreases with the increase of the molar ratio of carbon to iron (C:Fe). The Brunauer-Emmett-Teller characterization showed that the surface area as high as 255.6 m2/g is achieved by of the Fe2O3/C nanocomposite with the molar ratio of C:Fe of 1:1.

scholarly journals Electrochemical Properties of Ce0.5Sr0.5 (Co0.8Fe0.2)1−xZrxO3−δ Cathode Materials for Low Intermediate Temperature Solid Oxide Fuel Cells (LIT-SOFCs) Synthesized by Sol-Gel Method

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Beyene Tesfaw Ayalew ◽  
P. Vijay Bhaskar Rao
Keyword(s):  
Electrochemical Properties ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Electronic Conductivity ◽  
Partial Substitution ◽  
Sem Images ◽  
Gel Method ◽  
Sol Gel Method ◽  
Crystallite Sizes ◽  
Xrd Patterns

Ce0.5Sr0.5 (Co0.8Fe0.2)1−x ZrxO3−δ (CSCFZ) powders were synthesized by the sol-gel method and characterized to study structural and electrochemical properties. X-ray diffractometer (XRD) patterns of all samples give nanosized particles of a high-degree crystalline cathode having a cubic-type perovskite structure of space group Pm-3m with the existence of oxygen vacancies in the lattices. The results have the perovskite phase with average crystallite sizes of 26.57 nm, 18.14 nm, 18.13 nm, and 18.12 nm with porosities of 9.93%, 9.87%, 9.50%, and 9.08% for x = 0, 0.1, 0.15, and 0.2, respectively. Scanning electron microscope (SEM) micrographs showed the presence of pores on the microstructure. Average grain sizes of prepared samples found from SEM images were in the range of 105.30–183.02 nm. The partial substitution of zirconium at the B-site shows more stable materials than the host without decreasing the porosity that much. The results of electronic conductivity analyzed by the four-probe dc technique show that the conductivity of synthesized materials increases with the increment of both dopant concentration and temperature by the decrement of area specific resistances. The electrical conductivity of CSCFZ steadily increased with the increment of temperature which reached 42.76 Scm−1 at around 450°C.

The Microwave Assisted Synthesis of Imine Derivative Ligands for Nickel(II) Complex as Catalyst Precursors in Glucose Conversion to Sorbitol

2019 ◽  
Vol 811 ◽  
pp. 47-54
Author(s):  
Deana Wahyuningrum ◽  
Irma Mulyani ◽  
Ray Putra Prajnamitra
Keyword(s):  
Particle Size ◽  
Catalytic Activity ◽  
Organic Synthesis ◽  
Average Particle Size ◽  
Microwave Assisted Synthesis ◽  
Average Particle ◽  
Calcination Process ◽  
Microwave Assisted ◽  
Good Catalytic Activity ◽  
L1 And L2

Two imine derivative ligands, L1 and L2, have been synthesized using the microwave assisted organic synthesis (MAOS) method from the reaction between bibenzoyl and L-tryptophan and L-Histidine, respectively. The ligands were further transformed into two nickel(II) complex, C1 and C2, as the precursors of catalysts in glucose conversion to sorbitol. The two NiO/SiO2 catalysts, K1 and K2, have been generated through the calcination process of complex C1 and C2, respectively, which were previously impregnated into silica. The K1 catalyst with average particle size of 5 nm shows good catalytic activity, with no presence of any nickel leached into the solution, and has successfully converted 21.99% of glucose into sorbitol. The K2 catalyst with average particle size of 10 nm also shows good catalytic activity and has successfully converted 32.30% of glucose into sorbitol, although it shows the presence of leached nickel.

scholarly journals Synthesis and Properties of p-Si/n-Cd1−xAgxO Heterostructure for Transparent Photodiode Devices

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 425
Author(s):  
Mannarsamy Anitha ◽  
Karuppiah Deva Arun Kumar ◽  
Paolo Mele ◽  
Nagarajan Anitha ◽  
Karunamoorthy Saravanakumar ◽  
...  
Keyword(s):  
Thin Films ◽  
Visible Region ◽  
Near Band Edge ◽  
Sem Images ◽  
Ag Doping ◽  
Nebulizer Spray Pyrolysis ◽  
Crystallite Sizes ◽  
Amorphous Glass ◽  
Set Up ◽  
Xrd Patterns

We developed silver-doped Cd1–xAgxO thin films (where x = 0, 0.01, 0.02, 0.03 and 0.04) on amorphous glass substrate by an automated nebulizer spray pyrolysis set-up. The XRD patterns show rock salt cubic crystal structures, and the crystallite sizes vary with respect to Ag doping concentrations. SEM images exhibited a uniform distribution of grains with the addition of Ag; this feature could support the enhancement of electron mobility. The transmittance spectra reveal that all films show high transmittance in the visible region with the observed bandgap of about 2.40 eV. The room temperature photoluminescence (PL) studies show the increase of near-band-edge (NBE) emission of the films prepared by different Ag doping levels, resulting in respective decreases in the bandgaps. The photodiode performance was analyzed for the fabricated p-Si/n-Cd1–xAgxO devices. The responsivity, external quantum efficiency and detectivity of the prepared p-Si/n-Cd1–xAgxO device were investigated. The repeatability of the optimum (3 at.% Ag) photodiode was also studied. The present investigation suggests that Cd1–xAgxO thin films are the potential candidates for various industrial and photodetector applications.

Comparative study of conventional and microwave heating of polyacrylonitrile-based fibres

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guozhen Zhao ◽  
Jianhua Liu ◽  
Lei Xu ◽  
Shenghui Guo
Keyword(s):  
Microwave Heating ◽  
Surface Defects ◽  
Energy Dispersive Spectrometer ◽  
Xrd Analysis ◽  
Economic Benefits ◽  
Heating Time ◽  
Oxidation Temperature ◽  
Conventional Heating ◽  
Heating Method ◽  
Molecular Arrangement

Abstract The effects of the conventional heating method and the microwave heating method on polyacrylonitrile-based fibres in the temperature range of 180–280 °C were investigated. Fourier transform infrared spectroscopy, X-ray wide-angle scattering, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy and bulk density were used to characterise the properties of the samples. Results show that the microwave heating method can shorten the pre-oxidation time, reduce pre-oxidation temperature and reduce the number of surface defects. The pre-oxidised fibres obtained by the microwave heating method exhibit not only good crystallite size but also a smooth surface. Atomic morphology and molecular arrangement are orderly inside the fibre. The FT-IR spectrum shows that the oxidation reaction occurs at 220 °C, and the CI value of PAN fibers stabilised by microwave heating is the larger than the fibers stabilised by conventional heating. XRD analysis shows that fibers stabilised by microwave heating have low stack domains. The SEM and Raman spectra indicate that hydrogen peroxide can improve the surface finish of the fibers and reduce defects. Microwave heating can reduce the pre-oxidation temperature by about 20 °C and shorten the heating time. The economic benefits of using this method are significantly improved.

scholarly journals Preparation and application of carbon and hollow TiO2 microspheres by microwave heating at a low temperature

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 200-209
Author(s):  
Caiyun Zhang ◽  
Chunhong Li ◽  
Bolin Ji ◽  
Zhaohui Jiang
Keyword(s):  
Low Temperature ◽  
Microwave Heating ◽  
Raw Material ◽  
Carbon Microspheres ◽  
Microwave Assisted ◽  
The Core ◽  
Good Crystallinity ◽  
Carbon Core ◽  
Microwave Assisted Method ◽  
Uniform Particle Size

Abstract A fast, simple, and energy-saving microwave-assisted approach was successfully developed to prepare carbon microspheres. The carbon microspheres with a uniform particle size and good dispersity were prepared using glucose as the raw material and HCl as the dehydrating agent at low temperature (90°C) in an open system with the assistance of microwave heating. The carbon microspheres were characterized by elemental analysis, XRD, SEM, FTIR, TG, and Raman. The results showed that the carbon microspheres prepared under the condition of 18.5% (v/v) HCl and heating for 30 min by microwave had a narrow size distribution. The core–shell structure of the carbon core and TiO2 shell was prepared with (NH4)2TiF6, H3BO3 using the microwave-assisted method. The hollow TiO2 microspheres with good crystallinity and high photocatalytic properties were successfully prepared by sacrificing the carbon microspheres.

Preparation and Characterization of NTC NiMn2O4-La1-xCaxMnO3 (0≤x≤0.3) Composite Ceramics

2013 ◽  
Vol 716 ◽  
pp. 78-83 ◽  
Author(s):  
Hui Min Zhang ◽  
Fang Guan ◽  
Ai Min Chang ◽  
Li Jun Zhao
Keyword(s):  
Electrical Resistivity ◽  
Perovskite Structure ◽  
Spinel Structure ◽  
Thermal Constant ◽  
Inrush Current ◽  
Composite Ceramics ◽  
Sem Images ◽  
Conventional Solid State Reaction ◽  
Different Temperatures ◽  
Xrd Patterns

Composite ceramics made of spinel structure NiMn2O4 and CaO-doped perovskite structure LaMnO3 were prepared by a conventional solid state reaction and sintered at different temperatures. The XRD patterns have shown that the major phases presented in the sintered samples are NiMn2O4 compounds with the spinel structure, La1-xCaxMnO3 with the perovskite structure and NiO with a monoclinic structure. SEM images show that the density and grain size of the composite ceramics increases with sintered temperature increasing. The electrical resistivity of the composite ceramics at 25°C is found to change significantly depending on the CaO content, while the thermal constant B is still reasonably large in the range of 2400 to 3000 K. For the composition x = 0.1, the composite with a low electrical resistivity (ρ25°C=4.46Ω·cm) and moderate B value (B25/50=2762K) was obtained. These composites could be applied as potential candidates for NTC thermistors in the suppression of the inrush current.

Synthesis, Characterization and Properties of PANI/(La-Nd Doped BaFe12O19) Composites

2017 ◽  
Vol 727 ◽  
pp. 327-334
Author(s):  
Yan Wang ◽  
Jun Wang ◽  
Xiao Fei Zhang ◽  
Ya Qing Liu
Keyword(s):  
Sol Gel ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Structure Morphology ◽  
Xrd Patterns ◽  
Hexagonal Platelet ◽  
Peak Value ◽  
Properties Of Composites

La-Nd co-doped barium hexaferrites, Ba0.7(LamNdn)0.3Fe12O19 (D-BaM), were successfully prepared by sol-gel method. PANI / D-BaM composites were synthesized by in-situ polymerization in solution. The structure, morphology and properties of samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), four-probe conductivity tester and vector network analyzer. The XRD patterns showed that the crystal structure of all the samples exist as M-type phases. The SEM images revealed that the particles presented a hexagonal platelet-like morphology. The magnetic properties could be improved by substitutions of La and Nd ions. The saturation magnetization (Ms) and coercive force (Hc) increased with the change of La / Nd ratio to the maximum at La / Nd = 3:1. The doped particles have also been embedded in conductive PANI to prepare electromagnetic materials, and the conductivity kept on the order of 10-2. The microwave absorbing properties of composites at 30 MHz-6 GHz improved obviously, the peak value of reflection loss could reach-7.5 dB.

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