Amorphous alumino-silicate materials in a Brazilian hydromorphic lateritic soil

Soil Research ◽  
2002 ◽  
Vol 40 (3) ◽  
pp. 465 ◽  
Author(s):  
Angélica F. Drummond C. Varajão ◽  
Robert J. Gilkes ◽  
Robert D. Hart
Keyword(s):  
Lateritic Soil ◽  
Soil Profiles ◽  
High Concentration ◽  
Atom Ratio ◽  
Amorphous Phases ◽  
Al Content ◽  
Transmission Electron ◽  
Bulk Chemical ◽  
Alumino Silicate ◽  
High Al Content

Two ancient lateritic soil profiles from Brazil that are now experiencing hydromorphic conditions were investigated by chemical extractions, X-ray diffraction, differential thermal and thermogravimetric analysis, and analytical transmission electron microscopy (ATEM) to identify if the hydromorphic conditions had affected soil minerals. The soils are composed of gibbsite and kaolinite with less quartz, anatase, goethite, pedogenic chlorite, and amorphous alumino-silicate phases. These last 2 constituents occur in the middle and upper horizons of both soil profiles, together with considerable amounts of organic carbon. Analytical TEM showed that the amorphous phases enveloped corroded gibbsite and kaolinite crystals and may indicate the transformation of these minerals to amorphous phases. The amorphous phases have a similar microfabric to that of allophane and ATEM analyses of the amorphous phases gave an Al/Si atom ratio that was always >2, and commonly about 10. These atom ratios are consistent with the bulk chemical results obtained using pyrophosphate, oxalate, and dithionite extractants, but not with the theoretical ratio for allophane. The Al/Si atom ratio of the amorphous phases was related to the Al content of the mineral enveloped by the amorphous phases, i.e. gibbsite or kaolinite. This association supports the interpretation that the amorphous phases formed from the crystalline minerals. The saturated condition of the profiles, together with the high concentration of organic matter in the upper horizons, favours dissolution of the original gibbsite and kaolinite in the laterite and their transformation to amorphous alumino-silicate phases with a high Al content.

Microstructure and Distribution of Low Content Elements in AlNiCo 9

2017 ◽  
Vol 898 ◽  
pp. 1669-1674 ◽  
Author(s):  
Bin Shao ◽  
Bing Bing Li ◽  
Chun Hong Li ◽  
Yi Long Ma ◽  
Qiang Zheng ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Magnetic Domain ◽  
Magnetic Force Microscope ◽  
X Ray Diffraction ◽  
Rich Phase ◽  
X Ray ◽  
Al Content ◽  
Transmission Electron ◽  
Titanium Sulfide ◽  
High Al Content

The microstructure and the chemistry distribution of AlNiCo 9 samples were characterized by the X-ray diffraction, magnetic force microscope, field emission scanning electron microscopy and transmission electron microscope. An interface of a high Al content was formed near the FeCo-rich phases with a size of about 30 nm. S elements mainly combined with Ti to form titanium sulfide bars with the length between 70-150 μm, while S elements was not confirmed in the nanostructured FeCo-rich phase and AlNi-rich phase. Si and Nb preferably existed in the NiAl-rich phase, and a higher content Nb near the Cu precipitate boundary was observed. Moreover, the magnetic domain structure of AlNiCo 9 was also studied.

Damage and Lattice Strain in Ion-Irradiated AlxGai-xAs

1994 ◽  
Vol 354 ◽  
Author(s):  
P. Partyka ◽  
R.S. Averback ◽  
D.V. Forbes ◽  
J.J. Coleman ◽  
P. Ehrhart ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Lattice Parameter ◽  
Large Strains ◽  
X Ray Diffraction ◽  
Al Content ◽  
Plane Lattice ◽  
Transmission Electron ◽  
Out Of Plane ◽  
Radiation Induced ◽  
High Al Content

AbstractRadiation-induced damage and strain in AlxGai-xAs (x=5 to 1) were investigated by measurements of the lattice parameter using x-ray diffraction. Irradiations employed MeV C, Ar and Au ion beams with a substrate temperature of 80 K. For samples with high Al content, the out-of-plane lattice parameter increased with fluence at low doses, saturated, and then decreased to nearly its original value. The in-plane lattice parameter did not change, throughout. These results were independent of the irradiation particle when scaled by damage energy. For the Al.5Ga.5As samples, however, the out-of-plane lattice parameter increased monotonically with dose to large strains until the layer amorpnized. Selected samples were examined by high resolution and conventional transmission electron microscopy (TEM). Channeling Rutherford backscattering spectrometry (CRBS) was also employed to monitor the buildup of damage in many samples. Recovery of the lattice parameter during subsequent thermal annealing was also investigated.

HRTEM investigation of intralayer and interlayer stacking defects and pyrophyllite interlayers in illite

2010 ◽  
Vol 74 (3) ◽  
pp. 451-461 ◽  
Author(s):  
Tao Chen ◽  
Hejing Wang ◽  
Roger Mason ◽  
Li Chen
Keyword(s):  
Electron Microscope ◽  
Early Stage ◽  
Energy Dispersive Spectrometer ◽  
Tetrahedral Sheet ◽  
Al Content ◽  
Transmission Electron ◽  
Metastable Structures ◽  
Interlayer Region ◽  
Complex Structural ◽  
High Al Content

AbstractMetastable authigenic 1M illite from shale of diagenetic grade has been studied using a high-resolution transmission electron microscope (HRTEM) equipped with energy-dispersive spectrometer, X-ray diffraction, and scanning electron microscope. The illite occurs as deformed flakes deficient in interlayer K+ cations with 0.6 per half cell, and with abnormally high Al in both octahedral and tetrahedral sites. Complex structural adjustments reflecting the unusual chemical composition are observed in images of illite at near-atomic resolution. Different distances and directions of intralayer shift between the upper tetrahedral sheet and the lower tetrahedral sheet within 2:1 layers are found in this sample. Intralayer undershift structure coupled with interlayer displacement is found in a 1M illite crystal, and intralayer overshift structure coupled with no interlayer displacement is found in a 1M domain of a larger crystal. Two tetrahedral sheets across the interlayer region sometimes deviate from ideal positions causing interlayer displacement. Two pyrophyllite layers are found overlying a stack of ordered 1M illite layers, and are overlain by illite layers with anomalous interlayer offsets. This offset is considered to result from an increase in the lateral dimensions of the tetrahedral sheet due to anomalous high Al content. Our observation of intralayer and interlayer deficiencies indicate that authigenic illite that crystallized in the early stage of diagenesis at low temperatures tends to give rise to heterogeneous, disordered, and metastable structures.

Oxidation Kinetics and Microstructure of Wet-Oxidized MBE-Grown Short-Period AlGaAs Superlattices

2001 ◽  
Vol 692 ◽  
Author(s):  
René Todt ◽  
Katharine Dovidenko ◽  
Alexei Katsnelson ◽  
Vadim Tokranov ◽  
Michael Yakimov ◽  
...  
Keyword(s):  
Mechanical Stability ◽  
Optoelectronic Device ◽  
Nuclear Reaction Analysis ◽  
Al Content ◽  
Superlattice Structure ◽  
Transmission Electron ◽  
Short Period ◽  
Device Structures ◽  
Short Period Superlattices ◽  
High Al Content

AbstractThe kinetics of the wet oxidation process of MBE-grown high-Al-content AlAs/Al0.6Ga0.4As short-period superlattices (SPSLs) was investigated and compared to AlGaAs alloys and pure AlAs. We found that alloys and superlattices (SLs) have different oxidation characteristics. These differences were attributed to traces of the superlattice structure in the oxidized material. The microstructure and chemistry of SPSLs with an equivalent composition of Al0.98Ga0.02As was studied, using transmission electron microscopy, energy-dispersive x-ray spectroscopy, Rutherford backscattering, and nuclear reaction analysis for hydrogen-profiling. We also report on the mechanical stability of oxidized SPSL layers in optoelectronic device structures.

Is the Al Solubility Limit in SiC Temperature Dependent or not?

2005 ◽  
Vol 483-485 ◽  
pp. 125-128 ◽  
Author(s):  
Christophe Jacquier ◽  
Gabriel Ferro ◽  
Marcin Zielinski ◽  
Efstathios K. Polychroniadis ◽  
A. Andreadou ◽  
...  
Keyword(s):  
Vapour Deposition ◽  
Chemical Vapour ◽  
Solubility Limit ◽  
Temperature Dependent ◽  
Al Content ◽  
Transmission Electron ◽  
High Al Content ◽  
Secondary Ion ◽  
Tem Transmission Electron Microscopy

The so-called VLS (Vapour-Liquid-Solid) mechanism in an Al-Si melt has recently demonstrated the capability to grow at low temperature single crystalline 4H-SiC layers, with a high Al content. Using the newly developed VLS technique, we have deposited several 4H-SiC layers and determined the incorporated Al level by SIMS (Secondary Ion Mass Spectroscopy). Depending on the sample, we have found that the SIMS doping level ranges from 5x1019 to 1x1021 at.cm-3. This last value is the highest one reported so far for in-situ doped SiC:Al. From TEM (Transmission Electron Microscopy) analyses we show that the layers are single crystals, with a high density of defects located only at the lower interface and no foreign phase inclusion. These results compare well with the ones obtained in previous works using alternative doping techniques, like ion implantation, chemical vapour deposition or sublimation. It thus suggests that Al solubility limit in SiC is rather temperature independent.

scholarly journals Microstructure and Photothermal Conversion Performance of Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 Selective Absorbing Film for Non-Vacuum High-Temperature Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 124
Author(s):  
Haibin Geng ◽  
Hanzhe Ye ◽  
Xingliang Chen ◽  
Sibin Du
Keyword(s):  
Visible Light ◽  
Near Infrared ◽  
Substitutional Solid Solution ◽  
Experimental Conditions ◽  
Al Content ◽  
Spectrum Range ◽  
Light Interference ◽  
Transmission Electron ◽  
Conversion Performance ◽  
Columnar Grain

This paper aims to clarify the phase composition in each sub-layer of tandem absorber TiMoAlON film and verify its thermal stability. The deposited multilayer Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 films include an infrared reflectance layer, light interference absorptive layers with different metal doping amounts, and an anti-reflectance layer. The layer thicknesses of Ti, Mo-TiAlN, Mo-TiAlON, and Al2O3 are 100, 300, 200, and 80 nm, respectively. Al content increases to 12 at.% and the ratio of N/O is nearly 0.1, which means nitride continuously changes to oxide. According to X-ray Diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, the diffraction peak that appears at 2θ = 40° demonstrates that Mo element aggregates in the substitutional solid solution (Ti,Al)(O,N) columnar grain. TiMoAlON films have low reflectivity in the spectrum range of 300–900 nm. When Al content is more than 10 at.%, absorptivity is almost in the spectrum range from visible to infrared, but absorptivity decreases in the ultraviolet spectrum range. When Al content is increased to 12 at.%, absorptivity α decreases by 0.05 in the experimental conditions. After baking in atmosphere at 500 °C for 8 h, the film has the highest absorptivity when doped with 2 at.% Mo. In the visible-light range, α = 0.97, and in the whole ultraviolet-visible-light near-infrared spectrum range, α = 0.94, and emissivity ε = 0.02 at room temperature and ε = 0.10 at 500 °C.

scholarly journals High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2237
Author(s):  
Eder H. C. Ferreira ◽  
Angela Aparecida Vieira ◽  
Lúcia Vieira ◽  
Guilhermino J. M. Fechine
Keyword(s):  
Graphene Oxide ◽  
High Viscosity ◽  
Tribological Performance ◽  
Multilayer Graphene ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Mechanical Reinforcement ◽  
Transmission Electron ◽  
Twin Screw ◽  
Mechanical Tensile

Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE-UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a significant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomography, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction coefficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.

scholarly journals A New Nanocomposite Packaging Based on LASiS-Generated AgNPs for the Preservation of Apple Juice

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 760
Author(s):  
Maria Chiara Sportelli ◽  
Antonio Ancona ◽  
Annalisa Volpe ◽  
Caterina Gaudiuso ◽  
Valentina Lavicita ◽  
...  
Keyword(s):  
Metal Ion ◽  
Chemical Characterization ◽  
Average Diameter ◽  
Biological Action ◽  
Metal Species ◽  
Ion Release ◽  
Bioactive Materials ◽  
Transmission Electron ◽  
Metal Ion Release ◽  
Bulk Chemical

Designing bioactive materials, with controlled metal ion release, exerting a significant biological action and associated to low toxicity for humans, is nowadays one of the most important challenges for our community. The most looked-for nanoantimicrobials are capable of releasing metal species with defined kinetic profiles, either by slowing down or inhibiting bacterial growth and pathogenic microorganism diffusion. In this study, laser ablation synthesis in solution (LASiS) has been used to produce bioactive Ag-based nanocolloids, in isopropyl alcohol, which can be used as water-insoluble nano-reservoirs in composite materials like poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Infrared spectroscopy was used to evaluate the chemical state of pristine polymer and final composite material, thus providing useful information about synthesis processes, as well as storage and processing conditions. Transmission electron microscopy was exploited to study the morphology of nano-colloids, along with UV-Vis for bulk chemical characterization, highlighting the presence of spheroidal particles with average diameter around 12 nm. Electro-thermal atomic absorption spectroscopy was used to investigate metal ion release from Ag-modified products, showing a maximum release around 60 ppb, which ensures an efficient antimicrobial activity, being much lower than what recommended by health institutions. Analytical spectroscopy results were matched with bioactivity tests carried out on target microorganisms of food spoilage.

ARCHITECTURE OF FLOWER-LIKE rGO/CNTs-LOADED CuxO NANOPARTICLES AND ITS PHOTOCATALYTIC PROPERTIES

NANO ◽  
2013 ◽  
Vol 08 (05) ◽  
pp. 1350052 ◽  
Author(s):  
BIN ZENG ◽  
XIAOHUA CHEN ◽  
XUTAO NING ◽  
CHUANSHENG CHEN ◽  
HUI LONG
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Degradation Process ◽  
Photocatalytic Properties ◽  
High Concentration ◽  
Graphene Oxides ◽  
Transmission Electron ◽  
Time Scanning ◽  
Reduced Graphene ◽  
First Time

Novel flower-like composite architecture was successfully synthesized by spray drying and post-calcinating method for the first time. Scanning electron microscopy and transmission electron microscopy observations confirmed that reduced graphene oxides/carbon nanotubes hybrid (rGO/CNTs) formed a flower-like micrometer structure and Cu2O , CuO ( Cu x O , x = 1 or 2) nanoparticles were decorated inside them. The photocatalytic properties were further investigated by evaluating the photodegradation of a pollutant methyl orange (MO). The experimental results indicated that this novel architecture enhanced photocatalytic performance with 96.2% decomposition of MO after 25 min in the presence of H 2 O 2 under visible light irradiation, which was much higher than that of Cu x O powders (33.2%). This could be attributed to the more efficient adsorption of MO molecules on flower-like rGO/CNTs and provide a high concentration of MO near to the Cu x O nanoparticles, thus promoting the photocatalytic degradation process.

Silicon-Sapphire Interface: A High Resolution Electron Microscopy Study

1980 ◽  
Vol 2 ◽  
Author(s):  
Fernando A. Ponce
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Silicon Layer ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Resolution Limit ◽  
High Concentration ◽  
Transmission Electron ◽  
Resolution Electron

ABSTRACTThe structure of the silicon-sapphire interface of CVD silicon on a (1102) sapphire substrate has been studied in crøss section by high resolution transmission electron microscopy. Multibeam images of the interface region have been obtained where both the silicon and sapphire lattices are directly resolved. The interface is observed to be planar and abrupt to the instrument resolution limit of 3 Å. No interfacial phase is evident. Defects are inhomogeneously distributed at the interface: relatively defect-free regions are observed in the silicon layer in addition to regions with high concentration of defects.

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