scholarly journals Study of dielectric behavior and electrical properties of hematite α-Fe2O3 doped with Zn

2012 ◽  
Vol 44 (3) ◽  
pp. 307-321 ◽  
Author(s):  
M.V. Nikolic ◽  
M.P. Slankamenac ◽  
N. Nikolic ◽  
D.L. Sekulic ◽  
O.S. Aleksic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Spinel Phase ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Zn Content ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Two Phases

The effects of Zn-doping on the dielectric behavior and electrical properties of bulk ?-Fe2O3 have been studied. X-ray diffraction analysis revealed the presence of two phases in all samples: hematite and spinel ZnFe2O4, with the amount of spinel phase increasing with increasing Zn content. Scanning electron microscopy analysis combined with energy dispersive X-ray spectroscopy showed that the Zn-bearing phase occurred in the form of individual spinel ZnFe2O4 grains in a hematite matrix. DC conductivity was measured in the temperature range 25-225oC (298-498 K). Impedance spectroscopy measurements in the same temperature range were carried out in the frequency range 100Hz to 10 MHz. Increase in the Zn content resulted in increased electrical conductivity and higher values of the dielectric constant. The resistance and capacitance of grains and grain boundaries were analyzed by modeling the experimental results using an equivalent circuit.

A conformational polymorphic transition in the high-temperature ∊-form of chlorpropamide on cooling: a new ∊′-form

2009 ◽  
Vol 65 (6) ◽  
pp. 770-781 ◽  
Author(s):  
Tatiana N. Drebushchak ◽  
Yury A. Chesalov ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Structural Changes ◽  
Molecular Conformation ◽  
Polymorphic Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Temperature Range ◽  
Two Phases

Structural changes in the high-temperature ∊-polymorph of chlorpropamide, 4-chloro-N-(propylaminocarbonyl)benzenesulfonamide, C10H13ClN2O3S, on cooling down to 100 K and on reverse heating were followed by single-crystal X-ray diffraction. At temperatures below 200 K the phase transition into a new polymorph (termed the ∊′-form) has been observed for the first time. The polymorphic transition preserves the space group Pna21, is reversible and is accompanied by discontinuous changes in the cell volume and parameters, resulting from changes in molecular conformation. As shown by IR spectroscopy and X-ray powder diffraction, the phase transition in a powder sample is inhomogeneous throughout the bulk, and the two phases co-exist in a wide temperature range. The cell parameters and the molecular conformation in the new polymorph are close to those in the previously known α-polymorph, but the packing of the z-shaped molecular ribbons linked by hydrogen bonds inherits that of the ∊-form and is different from the packing in the α-polymorph. A structural study of the α-polymorph in the same temperature range has revealed no phase transitions.

scholarly journals Photocatalytic degradation of tartrazine dye using CuO straw-sheaf-like nanostructures

2017 ◽  
Vol 75 (6) ◽  
pp. 1421-1430 ◽  
Author(s):  
Martha Purnachander Rao ◽  
Jerry J. Wu ◽  
Abdullah M. Asiri ◽  
Sambandam Anandan
Keyword(s):  
Photocatalytic Degradation ◽  
Photocatalytic Performance ◽  
Chemical Precipitation ◽  
Degradation Pathway ◽  
Gas Chromatography Mass Spectrometry ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

Straw-sheaf-like CuO nanostructures were fruitfully synthesized using a chemical precipitation approach for the photocatalytic degradation assessment of tartrazine. Phase identification, composition, and morphological outlook of prepared CuO nanostructures were established by X-ray diffraction and scanning electron microscopy analysis. The photocatalytic performance of the synthesized CuO nanostructures was appraised in the presence of visible light and the possible intermediates formed during the photocatalytic degradation were analyzed by gas chromatography–mass spectrometry. A suitable degradation pathway has also been proposed.

Catalytic Olefin Hydroalkoxylation by Nano Particles of Pollucite

2015 ◽  
Vol 68 (6) ◽  
pp. 981 ◽  
Author(s):  
Sara Zamanian ◽  
Ali Nemati Kharat
Keyword(s):  
Nitrogen Adsorption ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Catalyst ◽  
Aromatic Alcohols ◽  
Electron Microscopy Analysis ◽  
Adsorption Surface ◽  
Microscopy Analysis ◽  
Temperature Programmed

The catalytic hydroalkoxylation of α,β-unsaturated esters, nitriles, and ethers with aliphatic and aromatic alcohols over pollucite using thermal and microwave-assisted methods was investigated. To study the effect of the alcohol structures on the mechanism of the hydroalkoxylation reaction, different alcohols, such as methanol to butanol, cyclohexanol, phenol, and 2-ethylhexanol were used. The activities of pollucite, in contrast to other basic solids, were scarcely affected by the presence of air and moisture. The correlation between alcohol acidity and reaction activity is discussed. The prepared pollucite was characterized by X‐ray diffraction, volumetric nitrogen adsorption surface area analysis, and CO2 temperature‐programmed desorption. Scanning electron microscopy analysis revealed that the size of the modified nano catalyst particles was under 40 nm.

Preparation of Al2O3/MgO Nano-Composite Particles for Bio-Applications

2020 ◽  
Vol 38 (4A) ◽  
pp. 586-593
Author(s):  
Hayder A. Sallal ◽  
Alla A. Abdul-Hameed ◽  
Farhad. M. Othman
Keyword(s):  
Composite Materials ◽  
Sol Gel ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Composite Particles ◽  
X Ray Diffraction ◽  
Nano Composite ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis

This study describes the preparation and study of the properties of Nano composite particles prepared in a sol-gel method which consists of two materials (Αl2Ο3-MgΟ). The powder was evaluated by x-ray diffraction analysis, scanning electron microscopy analysis (SEM), particle size analysis, and energy dispersive x-ray analysis (EDX) and antibacterial test. The evaluation results of the nanocomposite particles shows a good distribution of the chemical composition between aluminum oxide and magnesium oxide, smoothness in particles  size where it reached to (54.9, 59.8) nm at calcination in (550 0C and 850 0C) respectively, formation of different shapes of nanoparticles and different  phases of the Αl2Ο3 particles (kappa and gamma) and nanopowder have well antibacterial action, Therefore, this reflects the efficiency of the proposed method to manufacture the nanocomposite powder and the possibility of using this powder as a strengthening material for the composite materials and using these composite materials in bio applications, especially in the fabrication of artificial limbs.

SYNTHESIS AND CHARACTERIZATION OF HG-BASED SUPERCONDUCTING THIN FILMS PRODUCED STARTING FROM LASER-DEPOSITED PRECURSORS

2000 ◽  
Vol 14 (25n27) ◽  
pp. 2731-2736 ◽  
Author(s):  
M. BINDI ◽  
F. FUSO ◽  
N. PUCCINI ◽  
E. ARIMONDO ◽  
A. TAMPIERI ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Deposition ◽  
Precursor Film ◽  
Superconducting Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Zero Resistance ◽  
Microscopy Analysis

Correctly c-axis oriented HgBa 2 CaCu 2 O 6+δ thin films have been produced on (100) MgO single crystal substrates and characterized. Pulsed laser deposition has been exploited to deposit Hg-free Re-doped precursor which then underwent synthesis in evacuated and sealed quartz tubes. X-ray diffraction pattern of the precursor target shows the expected composition of oxides. Scanning electron microscopy analysis have been performed on the surface of the precursor film. Hg-1212 films have been analyzed by θ-2θ Bragg-Brentano X-ray diffractometry. The patterns show little contributions in composition of Hg-1223 phase. The films exhibit a transition temperature >120 K with zero-resistance at around 115 K.

scholarly journals Preparation, structure, surface and impedance analysis of Na2Zn0.5Mn0.5P2O7 ceramics

2017 ◽  
Vol 57 (3) ◽  
Author(s):  
Vilma Venckutė ◽  
Antonija Dindune ◽  
Dagnija Valdniece ◽  
Aija Krumina ◽  
Martynas Lelis ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Photoelectron Spectroscopy ◽  
Impedance Analysis ◽  
Solid State Reaction Method ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Temperature Range ◽  
Two Phases

The Na2Zn0.5Mn0.5P2O7 powder was prepared by the solid state reaction method. The powder structure was studied by X-ray diffraction (XRD) in the temperature range from room temperature (RT) to 520 K. The results of XRD measurements show that the obtained Na2Zn0.5Mn0.5P2O7 is a mixture of two phases: Na2MnP2O7, which crystallizes in the triclinic space group P1, and Na2ZnP2O7, which crystallizes in the tetragonal space group P42/mmm. The chemical compositions of the powder and ceramic samples were investigated by an energy dispersive X-ray spectrometer (EDX) and X-ray fluorescence spectroscopy (XFS). The surface of ceramics was examined by X-ray photoelectron spectroscopy (XPS). The electrical conductivity and dielectric permittivity of the ceramics were investigated from RT to 700 K in the frequency range 10–109 Hz. The relaxational dispersion of electrical conductivity in the investigated frequency and temperature range was found.

scholarly journals Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

2014 ◽  
Vol 46 (3) ◽  
pp. 377-383
Author(s):  
R. Souag ◽  
N. Kamel ◽  
Y. Mouheb ◽  
M. Hammadi ◽  
Z. Kamel ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Aluminosilicate Glass ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Alkali Oxides ◽  
Scanning Electron

New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350?C, followed by a nucleation at 564?C, during 2 h, and a crystal growth at 1010?C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD) analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM) coupled with energy dispersive X-ray (EDX) analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

The Effect of MgO Dopant on the Dielectric Properties of CaCu3Ti4O12 Ceramics

2012 ◽  
Vol 620 ◽  
pp. 219-223 ◽  
Author(s):  
Mohd Fariz Ab Rahman ◽  
Julie Juliewatty Mohamed ◽  
Mohd Fadzil Ain ◽  
Sabar Derita Hutagalung
Keyword(s):  
Single Phase ◽  
Lattice Expansion ◽  
Secondary Phases ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Scanning Electron ◽  
Mg Doped

The properties of undoped and Mg-doped CaCu3Ti4O12 (CCTO) ceramics have been studied. The samples were calcined at 900°C for 12 hours, and sintered at 1030°C for 10 hours. X-ray diffraction analysis on calcined samples shown the formation of CCTO phase with trace of secondary phases meanwhile completed formation of CCTO single phase obtained for sintered pellets. The peak positions of Mg-doped CCTO were slightly left-shifted from the undoped CCTO, attributed to the lattice expansion. Scanning electron microscopy analysis showed that the grains size becomes larger with the increment of dopant amount. Enhanced dielectric constant was observed in the Ca1-xMgxCu3Ti4O12 ceramics with x = 0.05 for the frequency range from 1 MHz to 1 GHz. The dielectric loss seem to be at lowest value when Ca1-xMgxCu3Ti4O12 ceramics with x = 0.10 at the same frequency range. The results indicate that Mg ions have effectively changed the properties of CCTO.

Production of 3Y-PSZ Powders by Co-Precipitation and Milling

2008 ◽  
Vol 54 ◽  
pp. 50-55
Author(s):  
Erika Furlani ◽  
Eleonora Aneggi ◽  
Stefano Maschio
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Amorphous Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Attrition Milling ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Co Precipitation ◽  
Scanning Electron

The present research compares properties and behaviour of co-precipitated 3Y-PSZ powders submitted, after co-precipitation, to different milling treatments. The characteristics of the different products were evaluated by measurement of particle size distribution, thermogravimetric analysis, X-ray diffraction, specific surface area and scanning electron microscopy analysis. It has been demonstrated that 1h of attrition milling enables the production of powders with micrometric particles: the dispersing liquid used on milling has little influence. Crystallization of the amorphous powder is achieved after 1h of high energetic milling, without any thermal treatment.

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