Grinding Assistance in the Transformation of Gibbsite to Corundum

2002 ◽  
Vol 17 (3) ◽  
pp. 712-717 ◽  
Author(s):  
Rosa M. Torres Sánchez ◽  
A. Boix ◽  
R. C. Mercader
Keyword(s):  
Isoelectric Point ◽  
Photoelectron Spectroscopy ◽  
Milling Process ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Contamination ◽  
Point Determination ◽  
Amorphous Surface

After gibbsite was milled for 5 min in a Cr-steel oscillating mill, corundum was obtained by heating the powder for 3 h at 800 °C. We found that iron contamination, produced by the milling process, is essential to attain the transformation at this low temperature and is located at the surface of the gibbsite particles. The knowledge of the oxidation state and location of the contaminant elements, necessary to control the solid-state reactions and/or phase transformations induced by the milling, was realized in this work by a characterization performed by chemical analysis, x-ray photoelectron spectroscopy, Mössbauer spectroscopy, and isoelectric point determination. The iron contamination amounted to about 3% (as Fe2O3) for the sample milled for 60 min. That the iron contamination that occurred mainly on the gibbsite amorphous surface was concluded after a comparison of the isoelectric point determination of the milled samples with that of a mechanical mixture of gibbsite and hematite. X-ray diffraction studies showed that gibbsite looses its crystallinity after the first 5 min of milling.

scholarly journals An Insight into Chemistry and Structure of Colloidal 2D-WS2 Nanoflakes: Combined XPS and XRD Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1969
Author(s):  
Riccardo Scarfiello ◽  
Elisabetta Mazzotta ◽  
Davide Altamura ◽  
Concetta Nobile ◽  
Rosanna Mastria ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Xrd Analysis ◽  
Crystal Habit ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Evaluation ◽  
Rational Understanding ◽  
Structural Inspection

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T’ and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples.

A Two-step Electrodeposition of Pd-Cu/Cu2O Nanocomposite on FTO Substrate for Non-enzymatic Hydrogen Peroxide Sensor

2021 ◽  
Vol 17 ◽  
Author(s):  
Ke Huan ◽  
Li Tang ◽  
Dongmei Deng ◽  
Huan Wang ◽  
Xiaojing Si ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cyclic Voltammetry ◽  
Photoelectron Spectroscopy ◽  
Chemical Structure ◽  
Pd Nanoparticles ◽  
Optimal Conditions ◽  
Potential Oscillation ◽  
X Ray Diffraction ◽  
X Ray

Background: Hydrogen peroxide (H2O2) is a common reagent in the production and living, but excessive H2O2 may enhance the danger to the human body. Consequently, it is very important to develop economical, fast and accurate techniques for detecting H2O2. Methods: A simple two-step electrodeposition process was applied to synthesize Pd-Cu/Cu2O nanocomposite for non-enzymatic H2O2 sensor. Cu/Cu2O nanomaterial was firstly electrodeposited on FTO by potential oscillation technique, and then Pd nanoparticles were electrodeposited on Cu/Cu2O nanomaterial by cyclic voltammetry. The chemical structure, component, and morphology of the synthesized Pd-Cu/Cu2O nanocomposite were characterized by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of Pd-Cu/Cu2O nanocomposite were studied by cyclic voltammetry and amperometry. Results: Under optimal conditions, the as-fabricated sensor displayed a broad linear range (5-4000 µM) and low detection limit (1.8 µM) for the determination of H2O2. The proposed sensor showed good selectivity and reproducibility. Meanwhile, the proposed sensor has been successfully applied to detect H2O2 in milk. Conclusion: The Pd-Cu/Cu2O/FTO biosensor exhibits excellent electrochemical activity for H2O2 reduction, which has great potential application in the field of food safety.

Synthesis of Ferromagnetic Germanides in 40Ge/60Mn Films: Magnetic and Structural Properties

2014 ◽  
Vol 215 ◽  
pp. 167-172
Author(s):  
Victor G. Myagkov ◽  
A.A. Matsunin ◽  
Y.L. Mikhlin ◽  
Victor S. Zhigalov ◽  
Liudmila E. Bykova ◽  
...  
Keyword(s):  
Solid State ◽  
Curie Temperature ◽  
Photoelectron Spectroscopy ◽  
Magnetic Measurements ◽  
Atomic Ratio ◽  
Photoelectron Spectra ◽  
Solid State Reactions ◽  
Ferromagnetic Phase ◽  
X Ray Diffraction ◽  
X Ray

Solid-state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy and magnetic measurements. The films have a nominal atomic ratio Ge:Mn = 40:60 and are investigated at temperatures from 50 to 500 °С. It is established that after annealing at ~120 °С, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 40Ge/60Mn interface. Increasing the annealing temperature to 500 °С leads to the formation of the ferromagnetic phase with a Curie temperature TC ~ 360 K and magnetization MS ~ 140-200 emu/cc at room temperature. Analysis of X-ray diffraction patterns and the photoelectron spectra suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3СxOy. The initiation temperature (~120 °С) of the Mn5Ge3 phase is the same both for solid-state reactions in Ge/Mn films, as well as for phase separation in GexMn1-x diluted semiconductors. We conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn1-x diluted semiconductors.

scholarly journals Synthesis of Uniformly Sized Bi0.5Sb1.5Te3.0 Nanoparticles via Mechanochemical Process and Wet-Milling for Reduced Thermal Conductivity

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 536
Author(s):  
Bo-In Park ◽  
Miri Shin ◽  
Jaeho Park ◽  
Jae-Seung Lee ◽  
Seung Yong Lee ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Milling Process ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Xps Spectra ◽  
X Ray ◽  
Mechanochemical Process ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma

In this study, Bi0.5Sb1.5Te3.0 (BST) nanoparticles (NPs) with high crystallinities were synthesized via a mechanochemical process (MCP). X-ray diffraction (XRD), and Raman and X-ray photoelectron spectroscopy (XPS) spectra of the BST NPs showed that the Bi, Sb, and Te powders successfully formed BiSbTe phase and transmission electron microscopy (TEM) images, verifying the high crystallinity and smaller size, albeit agglomerated. The as-synthesized BST NPs with agglomerated clusters were ground into smaller sizes of approximately 41.8 nm with uniform distribution through a simple wet-milling process during 7 days. The thermal conduction behaviors of bulk alloys fabricated by spark plasma sintering (SPS) of the BST NPs were studied by comparing those of samples fabricated from as-synthesized BST NPs and a BST ingot. The thermal conductivities (κ) of the BST nanocomposites were significantly reduced by introducing BST NPs with smaller grain sizes and finer distributions in the temperature range from 300 to 500 K. The BST nanocomposites fabricated from wet-milled BST NPs offered ultralow κ values of 0.84 W m−1 K−1 at approximately 398 K.

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.

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.

Fe3O4@ZrO2 magnetic nanoparticles as a new electrode material for sensitive determination of organophosphorus agents

2015 ◽  
Vol 7 (12) ◽  
pp. 5053-5059 ◽  
Author(s):  
Na-Na Li ◽  
Tian-Fang Kang ◽  
Jing-Jing Zhang ◽  
Li-Ping Lu ◽  
Shui-Yuan Cheng
Keyword(s):  
Photoelectron Spectroscopy ◽  
Magnetic Core ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Sensitive Determination ◽  
Core Shell Nanoparticles

In this study, Fe3O4@ZrO2 magnetic core–shell nanoparticles (NPs) were synthesized and were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

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