Electric Field Enhanced Synthesis of Nanostructured Tantalum Carbide

2002 ◽  
Vol 17 (3) ◽  
pp. 609-613 ◽  
Author(s):  
Olivia A. Graeve ◽  
Zuhair A. Munir
Keyword(s):  
Melting Point ◽  
Crystallite Size ◽  
Applied Field ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Tantalum Carbide ◽  
Low Field ◽  
Combustion Wave Velocity ◽  
High Fields

Nanocrystalline TaC was synthesized by the field-activated combustion method. The crystallite size ranged from about 30 to 55 nm, depending on the applied field. At low fields (8.54 ≤ E < 16.39 V cm−1) the average crystallite size was relatively unaffected by the field, but it showed a significant increase at fields higher than 16.39 V cm−1. From temperature measurements, this field was found to coincide with the melting of Ta. The combustion wave velocity likewise showed a significant increase when the temperature was at the melting point. The composition of the product showed a dependence on the magnitude of the applied field. At low field values (above a threshold) the product contained Ta2C. When synthesized at high fields, the product showed the presence of TaC phase only. The lattice parameter and the C/Ta ratio showed a slight dependence on the field, both increasing with an increase in the magnitude of the field.

scholarly journals Characterization of Mechanically Alloyed Nanocrystalline Fe(Al): Crystallite Size and Dislocation Density

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
M. Mhadhbi ◽  
M. Khitouni ◽  
L. Escoda ◽  
J. J. Suñol ◽  
M. Dammak
Keyword(s):  
Solid Solution ◽  
Dislocation Density ◽  
Crystallite Size ◽  
Average Crystallite Size ◽  
High Energy ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
High Energy Ball Mill

A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. In addition lattice microstrain, average crystallite size, dislocation density, and the lattice parameter were determined. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 2 and 20 h of milling, indicated the formation of a nanostructured Fe(Al) solid solution.

scholarly journals Influence of Ni substitution on structural, morphological, dielectric, magnetic and optical properties of Cu–Zn ferrite by double sintering sol–gel technique

2019 ◽  
Vol 09 (02) ◽  
pp. 1950020 ◽  
Author(s):  
Mohammad Sajjad Hossain ◽  
Yeasmin Akter ◽  
Mohammad Shahjahan ◽  
Muhammad Shahriar Bashar ◽  
Most. Hosney Ara Begum ◽  
...  
Keyword(s):  
Optical Properties ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Munk Function ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Elemental Analyses ◽  
Gel Technique

Polycrystalline NiCuZn ferrite (NixCu[Formula: see text]Zn[Formula: see text]Fe2O4; [Formula: see text], 0.3, 0.4 and 0.5) were prepared through sol–gel auto combustion method applying double sintering technique. Structural, morphological, elemental analyses (EDS), Fourier-transform infrared spectroscopy (FTIR), Direct Current (DC) electrical resistivity, dielectric, magnetic and optical properties of prepared samples were analyzed. XRD profiles reveal the formation of simple cubic spinel structure without any traceable impurity. The average crystallite size lies within the range of 22–29[Formula: see text]nm. Lattice parameter decreases with increasing Ni concentration. Room temperature DC resistivity was recorded from [Formula: see text] to [Formula: see text][Formula: see text][Formula: see text][Formula: see text]cm. Both dielectric constant ([Formula: see text]) and loss factor (tan[Formula: see text]) were decreased with increase of frequency while AC conductivity increases. FTIR absorption peak occurred at three different frequency ranges at 570–577[Formula: see text]cm[Formula: see text], 1635–1662[Formula: see text]cm[Formula: see text] and 3439–3448[Formula: see text]cm[Formula: see text]. Magnetic properties were investigated by using vibrating sample magnetometer (VSM). Decreasing trends were observed for saturation magnetization ([Formula: see text]), magnetic coercivity ([Formula: see text]) and remanant magnetization ([Formula: see text]) with the increase of Ni content. Optical band gap ([Formula: see text]2.70–2.79[Formula: see text]eV) were calculated from diffuse reflectance data by using Kubelka–Munk function.

Highly recyclable Ti0.97Ni0.03O1.97 catalyst coated on cordierite monolith for efficient transformation of arylboronic acids to phenols and reduction of 4-nitrophenol

2021 ◽  
Author(s):  
prasanna b ◽  
K M Usha ◽  
M. S. Hedge
Keyword(s):  
Crystallite Size ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Solution Combustion ◽  
Solution Combustion Method ◽  
Arylboronic Acids ◽  
Tio2 Catalyst ◽  
Efficient Transformation

A stable Ni2+ substituted TiO2 catalyst (Ti0.97Ni0.03O1.97) has been synthesized by solution combustion method with an average crystallite size of 7.5 nm. Ti1-xNixO2-x (x = 0.01 - 0.06) crystallize in...

scholarly journals Effect of Samarium Substitution on the Structural and Magnetic Properties of Nanocrystalline Cobalt Ferrite

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Sheena Xavier ◽  
Smitha Thankachan ◽  
Binu P. Jacob ◽  
E. M. Mohammed
Keyword(s):  
Crystallite Size ◽  
Single Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
Magnetic Characteristics ◽  
Typical Sample ◽  
Cobalt Ferrites ◽  
Phase Spinel ◽  
Structural Characterizations

A series of samarium-substituted cobalt ferrites (CoFe2−xSmxO4 with x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) was synthesized by the sol-gel method. The structural characterizations of all the prepared samples were done using XRD and FTIR. These studies confirmed the formation of single-phase spinel structure in all the compositions. The increase in the value of lattice parameter with increase in samarium concentration suggests the expansion of unit cell. The Hall-Williamson analysis is used for estimating the average crystallite size and lattice strain induced due to the substitution of samarium in the prepared samples. Crystallinity and the crystallite size are observed to increase with the concentration of samarium. The surface morphology and particle size of a typical sample were determined using SEM and TEM respectively. The substitution of samarium strongly influences the magnetic characteristics, and this is confirmed from the magnetization measurements at room temperature.

scholarly journals Formation of NanoscaleMg(x)Fe(1-x)O  (x=0.1,0.2,0.4)Structure by Solution Combustion: Effect of Fuel to Oxidizer Ratio

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Mohsen Ahmadipour ◽  
K. Venkateswara Rao ◽  
V. Rajendar
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Crystallite Size ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
X Ray ◽  
Particle Size And Morphology ◽  
Size And Morphology

Mg(x)Fe(1-x)O(magnesiowustite) nanopowder samples synthesized by solution-combustion method and fuel to oxidizer ratio (Ψ=1,1.25) are used as a control parameter to investigate how particle size and morphology vary withΨ. The method is inexpensive and efficient for synthesis of oxide nanoparticles. The average crystallite size ofMg(x)Fe(1-x)Onanoparticles was estimated from the full-width-half maximum of the X-ray diffraction peaks of powders using Debye-Scherrer’s formula; the average crystallite size varies from 16 nm to 51 nm. From X-ray diffraction analysis, it was observed thatMg(x)Fe(1-x)Onanoparticles have cubic structure. The particle size measured by particle size analyzer ranges from 37.7 nm to 73 nm which is in the order of XRD results. Thermal analysis was done by thermal gravimetric-differential thermal analyzer. The particle size and morphology of the synthesized powder were examined by transmission electron microscope and scanning electron microscope. The crystal size and particle size were compared with some of the most recently published research works by XRD and TEM. FTIR conforms formation of theMg(x)Fe(1-x)O.

scholarly journals Facile Synthesis of Spherical Flake-shaped CuO Nanostructure and Its Characterization towards Solar Cell Application

2021 ◽  
Vol 18 (18) ◽  
Author(s):  
Jemibha PAULDURAI ◽  
Ahila Mudisoodum PERUMAL ◽  
Dhanalakshmi JEYARAJA ◽  
Panimaya Valan Rakkini AMAL
Keyword(s):  
Solar Cell ◽  
Crystallite Size ◽  
Surface Area ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
Peak Position ◽  
Cuo Nanoparticles ◽  
Precipitation Method ◽  
Solar Cell Application ◽  
Morphological Studies

The aim of this work is to synthesis CuO nanoparticles and investigates their eminent properties to identify their diverse application capability in the field of solar cells.  In this work, CuO nanoparticles were synthesized by precipitation method using Copper (II) nitrate and Copper (II) chloride. Surface effects due to defects, structural properties related through lattice parameter, and crystallite sizes of nanoparticles have been identified from XRD. The crystal plane and reflection peak position was calculated using Bragg’s law. It showed that CuO nanoparticles have a monoclinic structure, and that the average crystallite size of CuO nanoparticles was 28.82 nm. n-type semiconductor behavior had a direct band of Eg = 1.465(2) eV, analyzed from optical studies by DRS. The band gap of the sample was determined from the reflectance spectra using Kubelka-Munk (K-M) function. Elements present were found through absorption peak of FTIR. The blue shifts observed in FTIR spectra in CuO nanoparticles were compared with that of bulk CuO, and absorption band agreed with XRD results.  Morphological studies revealed the formation of spherical flake-shaped formation of CuO. It had a higher surface area and was well-suited to solar cell applications. HIGHLIGHTS The CuO nanoparticles were synthesized by precipitation method The average crystallite size of CuO nanoparticles obtained in the range of 28.82 nm Spherical flake-shaped nanostruture with higher surface area formed in this method Optical property of CuO (Eg = 1.465 eV) and good electron mobility make it a suitable solar cell absorber material GRAPHICAL ABSTRACT

scholarly journals Investigation of Structural, Magnetic and Electrical Properties of Chromium Substituted Nickel Ceramic Nanopowders

2021 ◽  
Author(s):  
Rapolu Sridhar ◽  
D. Ravinder ◽  
J. Laxman Naik ◽  
K. Vijaya Kumar ◽  
N. Maramu ◽  
...  
Keyword(s):  
Structural Information ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Ion Concentration ◽  
Structural Parameter ◽  
Dielectric Parameters ◽  
Auto Combustion ◽  
Ray Density ◽  
Cr Doping

Nano-ceramic of NiCrxFe2-xO4 (0.1 ≤ x ≤ 1.0) ferrites were synthesized by citrate-gel auto combustion method. The structural parameter such as lattice parameter, X-ray density, bulk density and porosity variations with Cr doping were studied. The average crystallite size is in the range 8.5–10.5 nm. The surface morphology and elemental analysis was studied with SEM (EDAX) spectrum and the structural information analyzed with FTIR spectra. Magnetic properties were discussed with Cr3+ion concentration. Electrical parameters like dc resistivity and drift mobility were reported with function of temperature and dopent concentration from room temperature to well beyond Curie temperature and explained with hopping mechanism between Fe2+↔Fe3+ ions. The activation energies in ferri and para magnetic regions were investigated. Dielectric parameters like dielectric constant, dielectric loss and ac conductivity were investigated variation with frequency and composition.

Band Gap Narrowing of MgO and Mg0.95Zn0.05O Nanostructures

2020 ◽  
Vol 307 ◽  
pp. 273-278
Author(s):  
Nor Fadilah Chayed ◽  
Nurhanna Badar ◽  
Kelimah Elong ◽  
Norlida Kamarulzaman
Keyword(s):  
Band Gap ◽  
Crystallite Size ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Band Gap Energy ◽  
Synthesis Condition ◽  
Gap Energy ◽  
Band Gap Narrowing ◽  
Effect Of Doping

Preparation of MgO and Mg0.95Zn0.05O nanomaterials using self-propagating combustion method are done to investigate the effect of doping on the band gap energy. The synthesis condition has been optimized to obtain pure MgO and Mg0.95Zn0.05O materials which confirmed by XRD. FESEM results shows agglomeration of crystallite with average crystallite size of samples between 30 nm to 125 nm. The band gap obtained from the measurement of UV-Vis NIR spectrophotometer for MgO nanostructure is 6.36 eV which is lower than bulk MgO of 7.8 eV. The presence of Zn in Mg0.95Zn0.05O sample causes the narrowing of band gap to 5.33 eV.

scholarly journals Synthesis and Characterization of Ce3+-Doped Ni0.5Cd0.5Fe2O4 Nanoparticles by Sol–Gel Auto-Combustion Method

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1156
Author(s):  
Danyal Ahmad ◽  
Nasir Mehboob ◽  
Abid Zaman ◽  
Nabeel Ahmed ◽  
Kashif Ahmed ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystallite Size ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Xrd Analysis ◽  
Sem Images ◽  
X Ray ◽  
Auto Combustion ◽  
Ray Density

Cerium (Ce)-doped Ni0.5Cd0.5CexFe2−xO4 (0.0 ≤ x ≤ 0.20) was synthesized using the sol–gel auto-combustion method. X-ray diffraction (XRD) analysis revealed that all the samples retained spinel cubic crystal structure with space group Fd3m at 800 °C. Crystal structure parameters, such as lattice constant, average crystallite size, and X-ray density were estimated from the major XRD (311) peak. Bulk density and porosity were also calculated. The average crystallite size was estimated to be in the range of 20–24 nm. SEM images displayed agglomerated particles with a porous morphology. The dielectric constant (ε′) increased and the dielectric loss tangent (tanδ) decreased with rising Ce concentration. The hysteresis loop (M–H loop) was measured at room temperature using a vibrating-sample magnetometer (VSM), which showed a nonlinear decrease in magnetization and coercivity with increasing Ce concentration.

scholarly journals The Structural and Magnetic Properties of Gadolinium Doped CoFe2O4Nanoferrites

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qing Lin ◽  
Jinpei Lin ◽  
Yun He ◽  
Ruijun Wang ◽  
Jianghui Dong
Keyword(s):  
Magnetic Properties ◽  
Saturation Magnetization ◽  
Crystallite Size ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Structural And Magnetic Properties

Gadolinium substituted cobalt ferrite CoGdxFe2−xO4(x= 0, 0.04, 0.08) powders have been prepared by a sol-gel autocombustion method. XRD results indicate the production of a single cubic phase of ferrites. The lattice parameter increases and the average crystallite size decreases with the substitution of Gd3+ions. SEM shows that the ferrite powers are nanoparticles. Room temperature Mössbauer spectra of CoGdxFe22−xO4are two normal Zeeman-split sextets, which display ferrimagnetic behavior. The saturation magnetization decreases and the coercivity increases by the Gd3+ions.

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