scholarly journals XPS Study of Mechanically Activated YBa2Cu3O6+δand NdBa2Cu3O6+δ

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
A. V. Fetisov ◽  
G. A. Kozhina ◽  
S. Kh. Estemirova ◽  
V. B. Fetisov ◽  
V. Ya. Mitrofanov ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Photoelectron Spectroscopy ◽  
Temperature Treatment ◽  
Impurity Phase ◽  
Chemical Degradation ◽  
Partial Substitution ◽  
High Temperature Treatment ◽  
Complete Disappearance ◽  
Superconducting Transition ◽  
The Impact

Oxides RBa2Cu3O6+δ(R=Y, Nd) subjected to mechanical activation in AGO-2 mill have been studied by X-ray photoelectron spectroscopy (XPS), thermal analysis, and magnetometry. It has been shown that mechanoactivation accelerates chemical degradation under the impact of H2O and CO2in YBa2Cu3O6+δsamples. Degradation occurs in the standard way. Investigation of mechanically activated NdBa2Cu3O6+δhas revealed other results. It has been suggested that CO2can diffuse into its structure more freely than in YBa2Cu3O6+δ; as a result, carbonization may proceed directly in the volume of NdBa2Cu3O6+δand independently of the hydrolysis process. In addition, the mechanism of interaction between the oxide and water is not active and not “traditional” for the homologous series REBa2Cu3O6+δ(where RE = rare earth and Y)—the characteristic “color” phase (Nd2BaCuO5) is not formed during hydrolysis. It is known that high-temperature treatment of NdBa2Cu3O6+δoxide results in partial substitution of cations Ba by Nd; which is accompanied by decrease in the superconducting transition temperature and formation of the impurity phase Ba2Cu3O5+y. According to our data, mechanical activation of the resulting solid solution Nd1+xBa2−xCu3O6+δunexpectedly has led to the reverse redistribution of cations, which has been manifested in the complete disappearance of the impurity phase and increase inTc.

The effect of acid activation and calcination of halloysite on the efficiency and selectivity of Pb(II), Cd(II), Zn(II) and As(V) uptake

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 385-394 ◽  
Author(s):  
Paulina Maziarz ◽  
Jakub Matusik
Keyword(s):  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Structural Changes ◽  
Selective Adsorption ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Acid Activation ◽  
Subsequent Formation ◽  
X Ray ◽  
Mineral Structure

AbstractThe present study investigated the efficiency and mechanisms of aqueous Pb(II), Cd(II), Zn(II) and As(V) adsorption on natural (H), calcined (HC), and acid-activated halloysite (HA). The XRD and FTIR measurements indicated that the aluminosilicate framework was not affected by high-temperature treatment, in contrast to acid activation, which led to structural changes mainly in the tetrahedral sheet. The sorption of cations on H sample was low, though it was most effective for As(V). The X-ray photoelectron spectroscopy results suggested that removal of As(V) might be related to its reduction to As(III) involving oxidation of Fe(II) present in the mineral structure and/or iron minerals. The calcination enhanced halloysite sorption capacity for cations, while the As(V) sorption decreased. This was due to partial dehydroxylation and the subsequent formation of additional active sites. The acid treatment induced selective adsorption of Pb(II).

scholarly journals Synthesis of biomorphaus SiC-ceramics

2007 ◽  
Vol 61 (2) ◽  
pp. 75-78
Author(s):  
Adela Egelja ◽  
Jelena Gulicovski ◽  
Aleksandar Devecerski ◽  
Snezana Boskovic ◽  
Branko Matovic
Keyword(s):  
Photoelectron Spectroscopy ◽  
Abies Alba ◽  
Microstructural Characterization ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Sic Ceramics ◽  
Silica Source ◽  
Porous Sic ◽  
Highly Porous

The carbothermal reduction processing of partially mineralized fir (Abies alba) samples was used to obtain highly-porous SiC ceramics with cellular structure. The infiltration of TEOS (tetraetilortosilikat, Si(OC2H5)4) as a silica source, was conducted in order to carry out the mineralization process. Synthesis of the SiC was achieved with a C/SiO2 replica annealing at 1723 K in Ar atmosphere. The obtained samples were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The experimental results revealed that the hierarchical bimorphous wood structure was preserved even after high-temperature treatment. Microstructural characterization of the ceramics revealed the presence of the P-SiC phase and traces of the a-SiC phase.

scholarly journals Influence of Conditioning Temperature on Defects in the Double Al2O3/ZnO Layer Deposited by the ALD Method

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1038
Author(s):  
Katarzyna Gawlińska-Nęcek ◽  
Mateusz Wlazło ◽  
Robert Socha ◽  
Ireneusz Stefaniuk ◽  
Łukasz Major ◽  
...  
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
Atomic Layer ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Defect States ◽  
Paramagnetic Resonance ◽  
Transmission Electron ◽  
Conditioning Temperature ◽  
Defects Analysis

In this work, we present the results of defects analysis concerning ZnO and Al2O3 layers deposited by atomic layer deposition (ALD) technique. The analysis was performed by the X-band electron paramagnetic resonance (EPR) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) methods. The layers were either tested as-deposited or after 30 min heating at 300 °C and 450 °C in Ar atmosphere. TEM and XPS investigations revealed amorphous nature and non-stoichiometry of aluminum oxide even after additional high-temperature treatment. EPR confirmed high number of defect states in Al2O3. For ZnO, we found the as-deposited layer shows ultrafine grains that start to grow when high temperature is applied and that their crystallinity is also improved, resulting in good agreement with XPS results which indicated lower number of defects on the layer surface.

scholarly journals Characterisation of Activated Carbons Obtained from Rice Husk

2017 ◽  
Vol 18 (4) ◽  
pp. 299 ◽  
Author(s):  
A. Merkel ◽  
A. Satayeva ◽  
F. Cannon ◽  
C. Howell ◽  
St. Meikle ◽  
...  
Keyword(s):  
Rice Husk ◽  
Photoelectron Spectroscopy ◽  
Activated Carbons ◽  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Temperature Treatment ◽  
Exchange Capacity ◽  
High Temperature Treatment ◽  
Scanning Calorimetry ◽  
Ion Removal

Rice husk derived activated carbons doped with nitrogen have been studied using low temperature nitrogen adsorption, scanning electron microscopy, mercury porosimetry, thermogravimetric analysis combined with mass-spectrometry, differential scanning calorimetry and X-ray photoelectron spectroscopy. It has been shown that N-doped activated carbon produced by high temperature treatment of the starting material soaked with urea, has a significantly higher anion exchange capacity than the other samples studied, which correlates with its higher adsorption capacity towards nitrate ion removal from aqueous solutions with the initial concentration of 5 and 15 ppm.

scholarly journals Extrusion Processing of Pure Chokeberry (Aronia melanocarpa) Pomace: Impact on Dietary Fiber Profile and Bioactive Compounds

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 518
Author(s):  
Vera Schmid ◽  
Jan Steck ◽  
Esther Mayer-Miebach ◽  
Diana Behsnilian ◽  
Mirko Bunzel ◽  
...  
Keyword(s):  
Dietary Fiber ◽  
Water Solubility ◽  
Partial Substitution ◽  
Type I ◽  
Food Ingredient ◽  
Pectic Polysaccharides ◽  
Thermomechanical Stress ◽  
Extrusion Processing ◽  
Aronia Melanocarpa ◽  
The Impact

The partial substitution of starch with dietary fiber (DF) in extruded ready-to-eat texturized (RTE) cereals has been suggested as a strategy to reduce the high glycemic index of these food products. Here, we study the impact of extrusion processing on pure chokeberry (Aronia melanocarpa) pomace powder (CPP) rich in DF and polyphenols (PP) focusing on the content and profile of the DF fractions, stability of PP, and techno-functional properties of the extrudates. Using a co-rotating twin-screw extruder, different screw speeds were applied to CPP with different water contents (cw), which resulted in specific mechanical energies (SME) in the range of 145–222 Whkg−1 and material temperatures (TM) in the range of 123–155 °C. High molecular weight soluble DF contents slightly increase with increasing thermomechanical stress up to 16.1 ± 0.8 g/100 g dm as compared to CPP (11.5 ± 1.2 g/100 g dm), but total DF (TDF) contents (58.6 ± 0.8 g/100 g dm) did not change. DF structural analysis revealed extrusion-based changes in the portions of pectic polysaccharides (type I rhamnogalacturonan) in the soluble and insoluble DF fractions. Contents of thermolabile anthocyanins decrease linearly with SME and temperature from 1.80 ± 0.09 g/100 g dm in CPP to 0.24 ± 0.06 g/100 g dm (222 Whkg−1, 155 °C), but phenolic acids and flavonoids appear to be largely unaffected. Resulting techno-functional (water absorption and water solubility) and physical properties related to the sensory characteristics (expansion, hardness, and color) of pure CPP extrudates support the expectation that granulated CPP extrudates may be a suitable food ingredient rich in DF and PP.

Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP

2021 ◽  
pp. 002199832199945
Author(s):  
Jong H Eun ◽  
Bo K Choi ◽  
Sun M Sung ◽  
Min S Kim ◽  
Joon S Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Photoelectron Spectroscopy ◽  
Mechanical Performance ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Internal Damage ◽  
Impact Tests ◽  
Flexural Tests ◽  
The Impact

In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

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