Preparation of Mo (Si, Al) 2 by Microwave Assisted Combustion Synthesis

2011 ◽  
Vol 103 ◽  
pp. 509-512 ◽  
Author(s):  
Si Wen Tang ◽  
Jian Hui Yan ◽  
Cheng Zhang Peng
Keyword(s):  
Phase Composition ◽  
Combustion Synthesis ◽  
Phase Structure ◽  
Heating Temperature ◽  
Synthesis Method ◽  
Sem Analysis ◽  
Microwave Energy ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Al Substitution

Al substituted MoSi2composites were prepared by using microwave assisted synthesis method, which is a self-propagation synthesis ignited by microwave energy. The composition and microstructure of as combusted powder had been detected by XRD and SEM analysis. Result shows that the pre-heating temperature and phase composition of microwave assisted combustion synthesis is largely influenced by the content of aluminum. The phase structure of Mo(Si, Al)2alter from a mixture of MoSi2and Mo5Si3to nearly pure Mo (Si, Al)2with the increasing of Al substitution. The main mechanism is dissolution separation..

Assessment of Magnetic Properties between Fe and Ni Doped ZnO Nanoparticles Synthesized by Microwave Assisted Synthesis Method

2021 ◽  
Vol 317 ◽  
pp. 119-124
Author(s):  
Sabiu Said Abdullahi ◽  
Garba Shehu Musa Galadanci ◽  
Norlaily Mohd Saiden ◽  
Josephine Ying Chyi Liew
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Synthesis Method ◽  
Dilute Magnetic Semiconductors ◽  
High Coercivity ◽  
Microwave Assisted Synthesis ◽  
Ferromagnetic Behavior ◽  
Microwave Assisted ◽  
Doped Zno

The emergence of Dilute Magnetic Semiconductors (DMS) with a potentials for spintronic application have attracted much researches attention, special consideration has been given to ZnO semiconductor material due to its wide band gap of 3.37 eV, large exciting binding energy of 60 meV, moreover, its ferromagnetic behavior at room temperature when doped with transition metals. MxZn1-xO (M = Fe or Ni) nanoparticles were synthesized by microwave assisted synthesis method calcined at 600°C. The structural, morphological and magnetic properties of these nanoparticles were studied using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Vibrating Sample Magnetometer (VSM) respectively. Single phase Wurtzite hexagonal crystal structure was observed for the undoped and Fe doped ZnO nanoparticles with no any impurity, whereas Ni doped ZnO nanoparticles shows the formation of NiO impurities. The magnetic measurement reveals a diamagnetic behavior for the undoped ZnO meanwhile a clear room temperature ferromagnetism was observed for both Fe and Ni doped ZnO. Fe doped ZnO present a high saturation magnetization compared to Ni doped ZnO. However, Ni doped ZnO present high coercivity. The research was confirmed that Fe doped ZnO material will be good material combination for spintronic applications.

scholarly journals Nb2O5 nanoparticles obtained by microwave assisted combustion synthesis under different conditions

2021 ◽  
Vol 15 (2) ◽  
pp. 128-135
Author(s):  
Thaís Luiz ◽  
Fabio Nakagomi ◽  
Reny Renzetti ◽  
Guilherme Siqueira
Keyword(s):  
Combustion Synthesis ◽  
Diffuse Reflectance Spectroscopy ◽  
Low Cost ◽  
Synthesis Method ◽  
Particle Growth ◽  
Synthesis Temperature ◽  
Band Gap Energy ◽  
Stoichiometric Ratio ◽  
Synthesis Of Nanoparticles ◽  
Microwave Assisted

The microwave assisted combustion synthesis (MACS) as a new, quick and low cost synthesis method was used for preparation of niobium pentoxide (Nb2O5) powders. The present paper investigated the effect of reactant concentrations (ammonium niobium oxalate, urea and ammonium nitrate) on the characteristics of Nb2O5 nanoparticles. Three samples were synthesized with stoichiometric ratio between the fuel and oxidant (C1), excess of oxidant (C2) and excess of fuel (C3). In all samples, Nb2O5 crystalline nanoparticles with irregular morphology were detected. The synthesis of nanoparticles with smaller diameter in the C2 and C3 samples was confirmed by greater values of band gap energy measured through UV-Visible diffuse reflectance spectroscopy (indicating quantum confinement) and by the Rietveld refinement of X-ray diffraction patterns. The results showed that the amounts of oxidant and fuel can change synthesis temperature, influencing the final characteristics of the particles, such as size and existent phases. In these cases the excess of oxidant and fuel in the C2 and C3 samples, respectively, decreases the average synthesis temperature and decelerates the particle growth and the formation of the monoclinic phase.

scholarly journals Microwave-assisted synthesis of high thermal stability and colourless polyimides containing pyridine

2019 ◽  
Vol 6 (6) ◽  
pp. 190196 ◽  
Author(s):  
Kai Cheng ◽  
Jie-pin Hu ◽  
Yan-cheng Wu ◽  
Chu-qi Shi ◽  
Zhi-geng Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Synthesis Method ◽  
Optical Transmittance ◽  
Aromatic Diamine ◽  
Microwave Assisted Synthesis ◽  
Step Method ◽  
Light Emitting ◽  
Microwave Assisted ◽  
One Step ◽  
Biphenyltetracarboxylic Dianhydride

A novel aromatic diamine containing pyridyl side group, 4-pyridine-4,4-bis(3,5-dimethyl-5-aminophenyl)methane (PyDPM), was successfully synthesized via electrophilic substitution reaction. The polyimides (PIs) containing pyridine were obtained via the microwave-assisted one-step polycondensation of the PyDPM with pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′,4,4′-diphenylether tetracarboxylic dianhydride (ODPA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). Contrarily to the reported similar PIs, these PIs exhibit much higher thermal stability or heat resistance, i.e. high glass transition temperatures ( T g s) in the range of 358–473°C, and the decomposition temperatures at 5% weight loss over 476°C under nitrogen. They can afford flexible and strong films with tensile strength of 82.1–93.3 MPa, elongation at break of 3.7%–15.2%, and Young's modulus of 3.3–3.8 GPa. Furthermore, The PI films exhibit good optical transparency with the cut-off wavelength at 313–366 nm and transmittance higher than 73% at 450 nm. The excellent thermal and optical transmittance can be attributed to synthesis method and the introduction of pyridine rings and ortho-methyl groups. The inherent viscosities of PIs via one-step method were found to be 0.58–1.12 dl g −1 in DMAc, much higher than those via two-step method. These results indicate these PIs could be potential candidates for optical substrates of organic light emitting diodes (OLEDs).

Citrate complexation microwave-assisted synthesis of Ce0.8Zr0.2O2 nanocatalyst over Al2O3 used in CO oxidation for hydrogen purification: influence of composite loading and synthesis method

RSC Advances ◽  
2016 ◽  
Vol 6 (40) ◽  
pp. 34055-34065 ◽  
Author(s):  
Leila Rezaee ◽  
Mohammad Haghighi
Keyword(s):  
Co Oxidation ◽  
Synthesis Method ◽  
Composite Catalyst ◽  
Microwave Assisted Synthesis ◽  
Hydrogen Purification ◽  
Microwave Assisted ◽  
Microwave Combustion

Nanostructured Ce0.8Zr0.2O2/Al2O3 composite catalyst was synthesized by modified citrate complexation method. Utilizing microwave combustion endowed the sample with more uniform and homogenous pattern leading to better CO oxidation.

Microwave Synthesis and Properties of Thin Layer Pt Modified TiO2 Nanofibers Coating

2016 ◽  
Vol 721 ◽  
pp. 383-388
Author(s):  
Reinis Drunka ◽  
Jānis Grabis ◽  
Dzidra Jankovica ◽  
Aija Krūmiņa
Keyword(s):  
Thin Layer ◽  
Surface Area ◽  
Visible Light Irradiation ◽  
Microwave Synthesis ◽  
Raw Materials ◽  
Synthesis Method ◽  
Total Surface Area ◽  
Microwave Assisted Synthesis ◽  
Fiber Layer ◽  
Microwave Assisted

In the present work formation of macro-size TiO2 nanofiber layers in microwave synthesis were studied. Anatase nanopowder and 10M KOH solution were used as raw materials. Microwave assisted synthesis method permitted to obtain TiO2 nanofibres containing individual nanowires with a diameter of 5nm and a specific surface area up to 129m2/g. Macro size layer of TiO2 nanofibers was obtained on the surface of microwave vessel. Total surface area covered with TiO2 was about 390cm2. Modification with platinum allows to increase photocatalytical activity of TiO2 macro size fiber layer up to 94.4% in UV irradiation and up to 11.6% under visible light irradiation.

Microwave-assisted synthesis of BiFeO3 nanoparticles with high catalytic performance in microwave-enhanced Fenton-like process

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 82439-82446 ◽  
Author(s):  
Shuo Li ◽  
Guangshan Zhang ◽  
Heshan Zheng ◽  
Nannan Wang ◽  
Yongjie Zheng ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Bifeo3 Nanoparticles

Synthesis of BiFeO3 using microwave-assisted hydrothermal synthesis method.

Effect of Further Calcination on the Phase Structure of LiMn2O4 Prepared by a Solution Combustion Synthesis

2011 ◽  
Vol 66-68 ◽  
pp. 768-771
Author(s):  
Gui Yang Liu ◽  
Jun Ming Guo ◽  
Bao Sen Wang ◽  
Ying He
Keyword(s):  
Combustion Synthesis ◽  
Phase Structure ◽  
Raw Materials ◽  
Synthesis Method ◽  
Solution Combustion Synthesis ◽  
Perfect Crystal ◽  
Lattice Parameters ◽  
Calcination Time ◽  
Solution Combustion ◽  
Grain Sizes

In this paper, LiMn2O4 materials were prepared by a solution combustion synthesis method using acetate salts as raw materials and acetic acid as fuel. The effect of further calcination at 500°C and 600°C on the phase structure and composition were investigated. The composition and phase structure are determined by X-ray diffraction (XRD). XRD results indicated that the main phase of the products was LiMn2O4,and there was a trace amount Mn2O3 impurity in the products prepared at 500°C and 600°C. The impurity Mn2O3 in the products prepared at 500°C is increased with increasing calcination time, but the Mn2O3 in the products prepared at 600°C is decreased. The grain sizes of the products prepared at 500°C and 600°C are increased with increasing calcination time, and the grain sizes of the products prepared at 600°C are larger than these of the products prepared at 500°C. The lattice parameters of the products prepared at 500°C and 600°C are smaller than that of LiMn2O4 with perfect crystal, and the lattice parameters of the products are more close to that of LiMn2O4 with perfect crystal.

Photocatalytic Activity of Mixed Phase TiO2 from Microwave-Assisted Synthesis

2013 ◽  
Vol 664 ◽  
pp. 661-666 ◽  
Author(s):  
Nuchanaporn Pijarn ◽  
Sirithan Jeimsirilers ◽  
Supatra Jinawath
Keyword(s):  
Methylene Blue ◽  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Organic Compounds ◽  
Irradiation Time ◽  
Synthesis Method ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Bacteria And Fungi ◽  
Hydrolysis Of

Photocatalyst is an environmental clean-up material when exposed to light. It can decompose organic compounds, bacteria and fungi as well as foul odors. Titanium dioxide (TiO2) has long been well known for its powerful photocatalytic activity. However, its properties depend on several factors and synthesis method is one of them. In this work, TiO2powders were prepared by three methods, namely microwave-assisted hydrolysis of titanium oxysulfate (TiOSO4), hydrolysis of TiOSO4, and also by calcining of TiOSO4. Photocatalytic activity of the obtained TiO2powders were evaluated through the decomposition of methylene blue in comparison with P25 (Degussa). Results showed that the TiO2prepared at conditions of microwave 100 watts, irradiation time of 10 min was most effective when compared with the others in this work.

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