Search results for "grain"
showing 10 items of 752 documents
Magnetic and structural properties of the nanostructured Fe 1–x Si x system with x = 0.1, 0.2 and 0.3, mechanical alloyed and sintered
2007
The magnetic and structural properties of the nanostructured system Fe1–xSix with x = 0.1, 0.2 and 0.3 were studied by X-Ray diffraction (XRD), SEM, and Mossbauer Spectrometry (MS). The samples were prepared by compacting and sintering at two temperatures, 900 and 1000 uC, from powders obtained by means of two procedures: by elemental mixing of Fe and Si powders and by mechanical alloying (MA). For samples obtained from mixed powders and sintered at 900 and 1000 uC, XRD and MS show the presence of pure iron and silicon, indicating that these conditions do not favor alloying, except for the sample with 30 at.% and 1000 uC, for which, besides of iron and silicon patterns, the DO3 and FeSi pha…
Comparison between grain-size analyses using laser diffraction and sedimentation methods
2010
A comparison between laser diffraction method (LDM) and the sieve-hydrometer method (SHM) was carried out for 228 soil samples representing a different texture classification sampled in a Sicilian basin. The analysis demonstrated that the sand content measured by SHM can be assumed equal to that determined by LDM technique, while the clay fraction measured by LDM was lower than that measured by the SHM. A set of equations to transform LDM results to SHM results was proposed. The influence of the LDM measurements of clay on the estimated percentage of silt + very fine sand particles (particle diameter ranging from 0.002 mm to 0.1 mm), which is useful for estimating soil erodibility, was also…
A multi-step mechanism and integrity of titanate nanoribbons.
2014
A one-step hydrothermal treatment of TiO2 powders under strongly basic conditions has been used to synthesize titanate nanoribbons. The nanoparticles were thoroughly characterized using several methods including transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectrometry (XPS) to determine their morphological, structural and chemical characteristics. The influence of the nature and size of the TiO2 precursor and of the reaction duration on the formation of the nanoribbons was investigated. The conditions required to obtain only titanate nanoribbons with a width ranging from 100 to 200 nm and several tens of micrometers in length w…
An Analysis of the Broadening Induced by Beam Damage in Transmission Electron Diffraction Spots from an Oriented Aliphatic Monolayer
1991
We have analysed the progressive changes in diffraction spot shape during prolonged transmission electron diffraction observation of a soap monolayer supported on a thin polymer film. The material used to form the monolayer was cadmium eicosanoate (arachidate). The observed changes cannot be explained at all in terms of the chemical crosslinking which is known to occur as a result of beam damage, nor completely in terms of the strain fields caused by unbound dislocation defects of the crystalline lattice. The most plausible explanation involves the formation of linear dislocation aggregates which resemble grain boundaries but yet which are not linked into a continuous network. The evolution…
Textures and c-axis orientations of deformed quartz crystals from porphyric dikes of the Alpine »Root Zone« (Western Alps)
1986
Deformation textures and c-axis preferred orientations of quartz phenocrysts from porphyric dikes of the Alpine »Root Zone« have been formed under conditions of greenschist to low amphibolite facies. It is shown that the deformation textures as shear planes and kink bands, boudins, grain boundary sutures, subgrains, coarse and fine recrystallized grains, deformation lamellae and fractures are developed in a chronological sequence during first increasing and later decreasing temperatures. The c-axis orientations are chiefly influenced by kinking during the early stage of metamorphism and later by recrystallization but not by the initial orientations of the c-axes. The shape of crossed-girdle…
<title>Thermostimulated electronic and ionic processes in irradiated sapphire</title>
2003
Electronic and ionic thermostimulated (TS) relaxation (TSR) processes in nominally pure sapphire (α-Al2O3 grown with oxygen deficiency) have been investigated at 290 - 650 K by means of the TS current (TSC), ionic depolarization current (TSDC) and electron emission (TSEE) techniques. After thermal (ionic) polarization of the reduced sapphire wide (approximately 75 K) and asymmetric ionic dipolar TSDC peak at 590 K (disorientation of the anion vacancy-related dipoles) was detected. Above 450 - 500 K the anion vacancy hopping (migration) starts and their interaction with defects take place. This can lead to lattice dynamic disordering and anion vacancy diffusion-controlled processes in sapphi…
Microstructure and fabric development in ice: Lessons learned from in situ experiments and implications for understanding rock evolution
2014
Abstract In this contribution we present a review of the evolution of microstructures and fabric in ice. Based on the review we show the potential use of ice as an analogue for rocks by considering selected examples that can be related to quartz-rich rocks. Advances in our understanding of the plasticity of ice have come from experimental investigations that clearly show that plastic deformation of polycrystalline ice is initially produced by basal slip. Interaction of dislocations play an essential role for dynamic recrystallization processes involving grain nucleation and grain-boundary migration during the steady-state flow of ice. To support this review we describe deformation in polycr…
Deformation of melt-bearing systems—insight from in situ grain-scale analogue experiments
2005
Abstract The deformation behaviour of partially molten rocks was investigated using in situ analogue experiments with norcamphor+ethanol, as well as partially molten KNO 3 +LiNO 3 . Three general deformation regimes could be distinguished during bulk pure shear deformation. In regime I, above ca. 8–10 vol.% liquid (melt) fraction ( ϕ bulk ), deformation is by compaction, distributed granular flow, and grain boundary sliding (GBS). At ϕ bulk ϕ bulk (regime III), grains form a coherent framework that deforms by grain boundary migration accommodated dislocation creep, associated with efficient segregation of remaining liquid. The transition liquid fraction between regimes I and II ( ϕ LT ) dep…
Influence of a nano phase segregation on the thermoelectric properties of the p-type doped stannite compound Cu(2+x)Zn(1-x)GeSe4.
2012
Engineering nanostructure in bulk thermoelectric materials has recently been established as an effective approach to scatter phonons, reducing the phonon mean free path, without simultaneously decreasing the electron mean free path for an improvement of the performance of thermoelectric materials. Herein the synthesis, phase stability, and thermoelectric properties of the solid solutions Cu_(2+x)Zn_(1–x)GeSe_4 (x = 0–0.1) are reported. The substitution of Zn^(2+) with Cu^+ introduces holes as charge carriers in the system and results in an enhancement of the thermoelectric efficiency. Nano-sized impurities formed via phase segregation at higher dopant contents have been identified and are l…
Liver failure under valproic acid
2011
Valproic acid (VPA, 2-propylvaleric acid) is originally an antiepileptic drug, which has been in use for more than 30 years in over 100 countries. The clinical application of VPA has expanded in the last years. Approval has been granted by the FDA for treatment of migraine and cluster headache in 1996, and for treatment of mania and long-term prophylaxis of bipolar affective disorder in 1995. In ongoing studies, VPA has been reported to inhibit growth of several types of cancer cells; in addition, effects on neurodegeneration, and on virus replication in HIV infection have been demonstrated potentially expanding the application of VPA in the future. Despite a good tolerability of the drug, …