scholarly journals Ferroelectric perovskite nanopowders obtained by mechanochemical synthesis

2010 ◽  
Vol 4 (3) ◽  
pp. 99-106 ◽  
Author(s):  
Izabela Szafraniak-Wiza ◽  
Bozena Hilczer ◽  
Ewa Talik ◽  
Adam Pietraszko ◽  
Barbara Malic
Keyword(s):  
Mechanochemical Synthesis ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
20 Nm ◽  
Grain Core ◽  
Ferroelectric Perovskite

Simple perovskite nanopowders were fabricated by mechanochemical synthesis. High-energy milling process of respective oxides, leading to production of ferroelectric perovskites, was carefully investigated and characterized by X-ray diffraction, electron microscopy and X-ray excited photoelectron spectroscopy. It has been found that: (i) the powder consists of loosely packed grains with a broad distribution of sizes between a few nm and 45 nm, (ii) the grains possess core/shell structure, (iii) the grain core of sizes larger than about 20 nm exhibits well developed crystalline structure, (iv) the grains are coated by structurally disordered (amorphous) shell. Intermediate phases have been found in the process of PbTiO3 mechanosynthesis only. The obtained nanopowders were used for preparation of dense ceramics.

scholarly journals Investigation of the Reaction between Fe2O3 and Si Activated by Ball Milling

1996 ◽  
Vol 51 (8) ◽  
pp. 915-922 ◽  
Author(s):  
Giorgio Concas ◽  
Francesco Congiu ◽  
Anna Corrias ◽  
Carlo Muntoni ◽  
Giorgio Paschina ◽  
...  
Keyword(s):  
Ball Milling ◽  
Oxygen Transfer ◽  
Amorphous Matrix ◽  
High Energy ◽  
Milling Process ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
Energy Ball

Abstract The path of the reaction between Fe2O3 and Si, activated by high energy ball milling, has been investigated by X-ray diffraction and Mössbauer spectroscopy. Hematite reduction involves oxygen transfer from Fe to Si with the formation of intermediate phases containing Fe(II), which are then reduced to Fe(0). A steady state is reached in the milling process where the reduction of stoichiometric amounts of Fe2O3 and Si is not complete and an amount of Fe(II) in an amorphous matrix still remains. The same intermediate compounds are also observed in the milling process of mixtures with higher Fe2O3 /Si molar ratio.

Phase Transformation of Cu-Mo-C Powder during Mechanical Alloying and Annealing Process

2011 ◽  
Vol 233-235 ◽  
pp. 1678-1683
Author(s):  
Ke Sheng Zuo ◽  
Sheng Qi Xi ◽  
Jing En Zhou
Keyword(s):  
Phase Transformation ◽  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Graphite Powder ◽  
High Energy ◽  
Milling Process ◽  
Carbon Powder ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray

The allotropes of graphite and activated carbon were mixed with Cu and Mo powder, respectively. And the two groups of mixtures were high-energy milled and annealed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and DSC/TG were used to investigate the phase transformation during the milling and sintering process. For both groups of powder milled, Mo was hard to dissolve in Cu, and C mainly congregated in the surface of Cu powder. When Cu-Mo-graphite powder as milled was annealed, Mo2C was formed. In comparison to Cu-Mo-graphite alloyed powder, Cu-Mo-activated carbon powder partially formed Cu oxide and Mo oxide with higher binding energy during milling process, which caused higher reduction temperature of Cu oxide and reaction temperature of Mo2C.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

Study of Nanocrystalline NiAl Alloys Prepared by Mechanical Alloying

2012 ◽  
Vol 329 ◽  
pp. 19-28 ◽  
Author(s):  
M. Gherib ◽  
A. Otmani ◽  
A. Djekoun ◽  
A. Bouasla ◽  
M. Poulain ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Crystallite Size ◽  
Milling Time ◽  
Structural Features ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Refinement ◽  
20 Nm ◽  
Kinetics Of

Nanostructured Powders of Ni-20wt%Al and Ni-50wt%Al Were Prepared, by Mechanical Alloying under an Argon Atmosphere, from Elemental Ni and Al Powders Using a Planetary Ball Mill (type Fritsch P7) for Different Times (0.5-24h).). Microstructural and Structural Features of the Final Products Were Characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). the Results of the XRD Shows the Formation of the B2 (Ni Al) Phase after 2 Hours of Milling for both Systems. Also Detected Was the Ni3al Phase in Ni80al20after 4 Hours. Crystallite Size Refinement of the Final Product Occurred down to Nanometer Scales when the Milling Time Increased, and Attained 17 Nm in the Ni50al50System and 20 Nm in the other System, at 24 Hours. this Decrease in Crystallite Size Is Accompanied by an Increase in the Interval Level Strain. the Kinetics of Al Dissolution during the Milling Process of Ni50al50System Can Be Described by Two Regimes, Characterised by Different Values of Avrami Parameters which Are Calculated by Using the Johnson–Mehl–Avrami Formalism.

Phase Amorphization during High-Energy Milling of Mixtures of Zirconia with Yttria or Ceria Powders

2005 ◽  
Vol 498-499 ◽  
pp. 331-336 ◽  
Author(s):  
R. Muccillo ◽  
L. Franchi ◽  
J.T. Santos ◽  
I.C. Cosentino ◽  
E.N.S. Muccillo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Barium Carbonate ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Energy Milling ◽  
Transmission Electron ◽  
Strontium Ferrites

Strontium ferrites powders were obtained by high energy milling process after calcinations of iron oxide and barium carbonate. Phase formations and crystallite size was determined using X-ray diffraction. Morphology, particle size and agglomeration stages were analyzed using scanning and transmission electron microscopy. Results show particles in the range of 14 to 40 nanometers, large agglomerates and crystalline phases formation.

DSC-TGA Hydrogen Evaluation during Mechanical Milling of AlFe Intermetallic

2013 ◽  
Vol 755 ◽  
pp. 105-110 ◽  
Author(s):  
E. García de León M. ◽  
O. Téllez-Vázquez ◽  
C. Patiño-Carachure ◽  
G. Rosas
Keyword(s):  
Mechanical Milling ◽  
Milling Time ◽  
Hydrogen Generation ◽  
Pure Aluminum ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns

Fe40Al60 (at%) intermetallic alloy composition was obtained by conventional casting methods and subsequently subjected to high-energy mechanical milling under different conditions of humidity. All samples were characterized by X-ray diffraction patterns (XRD), transmission electron microcopy (TEM) and DSC-TGA thermogravimetric experiments. After the milling process, the amount of hydrogen generated was determined using thermogravimetric analysis and chemical reactions (stoichiometry). All techniques confirm the formation of bayerite phase which is attributed to the hydrogen embrittlement reaction between the intermetallic material and water to release hydrogen. It was observed that the hydrogen generation is increased as the ball milling time is increased. The quantity of hydrogen evaluated is similar to that obtained in previous reported experiments with pure aluminum and some of its alloys.

Synthesis of the Nanocrystalline/Nanosized NiFe2O4 Powder by Ceramic Method and Mechanical Milling

2012 ◽  
Vol 188 ◽  
pp. 27-30 ◽  
Author(s):  
Vasile Florin Tarța ◽  
Ionel Chicinaş ◽  
Traian Florin Marinca ◽  
Bogdan Viorel Neamţu ◽  
Florin Popa ◽  
...  
Keyword(s):  
Milling Time ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Polycrystalline Nickel ◽  
Powder Morphology ◽  
Chemical Homogeneity ◽  
Ceramic Method ◽  
X Ray ◽  
Nanometric Range

The polycrystalline nickel ferrite - NiFe2O4has been obtained by ceramic route starting from a stoichiometric mixture of oxides (NiO and α-Fe2O3powders). The obtained NiFe2O4was subjected to high energy ball milling. The formation of NiFe2O4by ceramic method and also the evolution of the powder during milling were studied by X-ray diffraction. The mean crystallite size of the NiFe2O4continuously decreases with the increasing of the milling time and for all the milling time it is in nanometric range. The particles sizes are drastically reduced by milling process. For the milled samples, the particles size is ranging from tens of microns to few nanometers. The powder morphology and local chemical homogeneity were investigated by scanning electron microscopy (SEM) and respectively by energy dispersive x-ray spectrometry (EDX).

Modification of the Structural Characteristics of the Tungsten Powder through Short Mechanical Milling Processes

2011 ◽  
Vol 672 ◽  
pp. 255-258
Author(s):  
Dana Salomie ◽  
Nicolae Jumate
Keyword(s):  
Fine Structure ◽  
Mechanical Milling ◽  
Structural Characteristics ◽  
Tungsten Powder ◽  
High Energy ◽  
Milling Process ◽  
Planetary Mill ◽  
X Ray Diffraction ◽  
Process Duration ◽  
X Ray

The objective of this study is to improve the sintering of W powder through increasing the density of the crystalline structure imperfections. The powder of W was processed by short processes of mechanical milling in a high energy planetary mill. The paper presents the influence of mechanical milling process duration upon the modifications of the structural characteristics of W powder. The fine structure has been studied by using X-ray diffraction.

scholarly journals The Effects of Doping Copper and Mesoporous Structure on Photocatalytic Properties of TiO2

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Yang Wang ◽  
Wubiao Duan ◽  
Bo Liu ◽  
Xidong Chen ◽  
Feihua Yang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Temperatures ◽  
Mesoporous Structure ◽  
Initial Solution ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Reduction Effect ◽  
20 Nm ◽  
As Effects

This paper describes a system for the synthesis of Cu-doped mesoporous TiO2nanoparticles by a hydrothermal method at relatively low temperatures. The technique used is to dope the as-prepared mesoporous TiO2system with copper. In this method, the copper species with the form of Cu1+, which was attributed to the reduction effect of dehydroxylation and evidenced by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), was well dispersed in the optimal concentration 1 wt.% Cu-doped mesoporous TiO2. In this as-prepared mesoporous TiO2system, original particles with a size of approximately 20 nm are aggregated together to shapes of approximately 1100 nm, which resulted in the porous aggregate structure. More importantly, the enhancement of the photocatalytic activity was discussed as effects due to the formation of stable Cu(I) and the mesoporous structure in the Cu-doped mesoporous TiO2. Among them, Cu-doped mesoporous TiO2shows the highest degradation rate of methyl orange (MO). In addition, the effects of initial solution pH on degradation of MO had also been investigated. As a result, the optimum values of initial solution pH were found to be 3.

scholarly journals Mechanochemical Reduction of Synthetic Sulphidic Copper-Bearing Minerals in an Industrial Scale

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Matej TEŠINSKÝ ◽  
Matej BALÁŽ ◽  
Michal RAJŇÁK ◽  
Mária KAŇUCHOVÁ ◽  
Peter BALÁŽ
Keyword(s):  
High Temperature ◽  
Ambient Temperature ◽  
Saturation Magnetization ◽  
Photoelectron Spectroscopy ◽  
Atmospheric Pressure ◽  
Magnetic Measurements ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Iron

In this paper the mechanochemical reduction of binary sulphides chalcocite (Cu2S) and covellite (CuS) by elemental iron wereinvestigated. The composition and properties of nano-powders prepared by high-energy milling were analyzed by X-ray diffraction,X-ray photoelectron spectroscopy and magnetic measurements. The XRD results showed that in case of chalcocite Cu2S the reactiontakes place until 360 minutes, as no elemental iron, could be identified afterwards. In case of covellite CuS, after 480 minutes of mechanochemicalreduction, a significant amount of non-reacted elemental iron could still be observed. The investigation of magneticproperties reveals significant decrease of saturation magnetization as a result of milling. XPS results showed a significant surfaceoxidation in both systems. Unlike the conventional high-temperature reduction of chalcocite and covellite, the mechanochemicalreduction is fast and ambient temperature and atmospheric pressure are sufficient for its propagation.

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