Zeitschriftenartikel: „Crystalline fraction“

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Schmidt, K. J., Y. Lin, M. Beaudoin, G. Xia, S. K. O’Leary, G. Yue und B. Yan. „The mean crystallite size within a hydrogenated nanocrystalline silicon based photovoltaic solar cell and its role in determining the corresponding crystalline volume fraction“. Canadian Journal of Physics 92, Nr. 7/8 (Juli 2014): 857–61. http://dx.doi.org/10.1139/cjp-2013-0526.

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We examine the dependence of the crystalline volume fraction on the mean crystallite size for hydrogenated nanocrystalline silicon based photovoltaic solar cells; this work builds upon an earlier study by Schmidt et al. (Mater. Res. Soc. Symp. Proc. 1536 (2013)). For each photovoltaic solar cell considered, the X-ray diffraction and Raman spectra are measured. Through the application of Scherrer’s equation, the X-ray diffraction results are used to determine the corresponding mean crystallite sizes. Through peak decomposition, the Raman results are used to estimate the corresponding crystalline volume fraction. Plotting the crystalline volume fraction as a function of the mean crystallite size, it is found that larger mean crystallite sizes tend to favor reduced crystalline volume fractions. The ability to randomly pack smaller crystallites with a greater packing fraction than their larger counterparts was suggested as a possible explanation for this observation.

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Schmidt, K. J., Y. Lin, M. Beaudoin, G. Xia, S. K. O'Leary, G. Yue und B. Yan. „The dependence of the crystalline volume fraction on the crystallite size for hydrogenated nanocrystalline silicon based solar cells“. MRS Proceedings 1536 (2013): 113–18. http://dx.doi.org/10.1557/opl.2013.599.

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ABSTRACTWe have performed an analysis on three hydrogenated nanocrystalline silicon (nc-Si:H) based solar cells. In order to determine the impact that impurities play in shaping the material properties, the XRD and Raman spectra corresponding to all three samples were measured. The XRD results, which displayed a number of crystalline silicon-based peaks, were used in order to approximate the mean crystallite sizes through Scherrer's equation. Through a peak decomposition process, the Raman results were used to estimate the corresponding crystalline volume fraction. It was noted that small crystallite sizes appear to favor larger crystalline volume fractions. This dependence seems to be related to the oxygen impurity concentration level within the intrinsic nc-Si:H layers.

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Li, J., A. W. Rate und R. J. Gilkes. „Fractionation of trace elements in some non-agricultural Australian soils“. Soil Research 41, Nr. 7 (2003): 1389. http://dx.doi.org/10.1071/sr02146.

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The fractionation of Ag, Ba, Co, Cr, Cu, Ni, Pb, V, and Zn in highly weathered soils was investigated using 5 operationally defined fractions: exchangeable, organic, amorphous Fe oxides, crystalline Fe oxides, and residual fraction. Crystalline Fe oxide and residual phases were the dominant hosts of Ag in the original soils, but for soils to which soluble Ag was added, much Ag was in the crystalline Fe oxide fractions and only a relatively small proportion of Ag was in the residual fraction. Crystalline Fe oxides and the residual fraction were also the major hosts to Co, Cr, Cu, Ni, Pb, V, and Zn.

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Wang, Fei Peng, Zheng Yong Huang und Jian Li. „Stretching Induced Crystalline-Phase Transition in Energy-Conversion Poly(Vinylidene Fluoride) (PVDF) Films“. Advanced Materials Research 1070-1072 (Dezember 2014): 589–93. http://dx.doi.org/10.4028/www.scientific.net/amr.1070-1072.589.

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Commercial poly (vinylidene fluoride) (PVDF) films are uniaxially stretched with varying rates at 110 °C in order to endow PVDF piezo-and pyroelectric by crystalline-phase transition from α to β during the stretching. The crystalline phases are determined by infrared spectroscopy. The β-phase content and its fraction in films increase as a result of stretching with high rates. In addition, higher stretching rates yield a slight increase of γ phase. The crystallite size is evaluated by means of X-ray diffraction. It is found that the β-phase crystallites become smaller with fast stretching, whereas the α-phase crystallites are cracked and disappear at high-speed stretching of 2.5 /min.

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Agbo, Solomon, Pavol Sutta, Pavel Calta, Rana Biswas und Bicai Pan. „Crystallized silicon nanostructures — experimental characterization and atomistic simulations“. Canadian Journal of Physics 92, Nr. 7/8 (Juli 2014): 783–88. http://dx.doi.org/10.1139/cjp-2013-0442.

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We have synthesized silicon nanocrystalline structures from thermal annealing of thin film amorphous silicon-based multilayers. The annealing procedure that was carried out in vacuum at temperatures up to 1100 °C is integrated in a X-ray diffraction (XRD) setup for real-time monitoring of the formation phases of the nanostructures. The microstructure of the crystallized films is investigated through experimental measurements combined with atomistic simulations of realistic nanocrystalline silicon (nc-Si) models. The multilayers consisting of uniformly alternating thicknesses of hydrogenated amorphous silicon and silicon oxide (SiO2) were deposited by plasma enhanced chemical vapor deposition on crystalline silicon and Corning glass substrates. The crystallized structure consisting of nc-Si structures embedded in an amorphous matrix were further characterized through XRD, Raman spectroscopy, and Fourier transform infrared measurements. We are able to show the different stages of nanostructure formation and how the sizes and the crystallized mass fraction can be controlled in our experimental synthesis. The crystallized silicon structures with large crystalline filling fractions exceeding 50% have been simulated with a robust classical molecular dynamics technique. The crystalline filling fractions and structural order of nc-Si obtained from this simulation are compared with our Raman and XRD measurements.

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Anwer, Afzana, S. Eilidh Bedford, Richard J. Spontak und Alan H. Windle. „Electron microscopy of crystalline structure in thermotropic random copolymers“. Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 1054–55. http://dx.doi.org/10.1017/s0424820100089585.

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Random copolyesters composed of wholly aromatic monomers such as p-oxybenzoate (B) and 2,6-oxynaphthoate (N) are known to exhibit liquid crystalline characteristics at elevated temperatures and over a broad composition range. Previous studies employing techniques such as X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) have conclusively proven that these thermotropic copolymers can possess a significant crystalline fraction, depending on molecular characteristics and processing history, despite the fact that the copolymer chains possess random intramolecular sequencing. Consequently, the nature of the crystalline structure that develops when these materials are processed in their mesophases and subsequently annealed has recently received considerable attention. A model that has been consistent with all experimental observations involves the Non-Periodic Layer (NPL) crystallite, which occurs when identical monomer sequences enter into register between adjacent chains. The objective of this work is to employ electron microscopy to identify and characterize these crystallites.

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Gatos, Konstantinos G., Chrysa Minogianni und Costas Galiotis. „Quantifying Crystalline Fraction within Polymer Spherulites“. Macromolecules 40, Nr. 4 (Februar 2007): 786–89. http://dx.doi.org/10.1021/ma0623284.

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Tsuchikawa, T., H. Kaneda, S. Oyabu, T. Kokusho, H. Kobayashi, M. Yamagishi und Y. Toba. „A systematic study of silicate absorption features in heavily obscured AGNs observed by Spitzer/IRS“. Astronomy & Astrophysics 651 (Juli 2021): A117. http://dx.doi.org/10.1051/0004-6361/202140483.

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Context. Heavily obscured active galactic nuclei (AGNs) are known to show deep silicate absorption features in the mid-infrared (mid-IR) wavelength range of 10–20 μm. The detailed profiles of the features reflect the properties of silicate dust, which are likely to include information on AGN activities obscured by large amounts of dust. Aims. We reveal AGN activities obscured by large amounts of dust through the silicate dust properties obtained from the mid-IR spectral bands. Methods. We selected 115 mid-IR spectra of heavily obscured AGNs observed by Spitzer/IRS and systematically analyzed the composition of silicate dust by spectral fitting using the 10 μm amorphous and 23 μm crystalline bands. Results. We find that the main component of the silicate dust obscuring AGNs is amorphous olivine, the median mass column density of which is one order of magnitude higher than those of the minor components of amorphous pyroxene and crystalline forsterite. The median mass fraction of the amorphous pyroxene, ∼2%, is significantly lower than that of the diffuse interstellar medium (ISM) dust in our Galaxy, while the median mass fraction of the crystalline forsterite, ∼6%, is higher than that of the diffuse ISM dust. We also find that the mass fractions of the amorphous pyroxene and the crystalline forsterite positively correlate with each other. Conclusions. The low mass fraction of the amorphous pyroxene suggests that the obscuring silicate dust is newly formed, originating from starburst activities. The relatively high mass fraction of crystalline forsterite implies that the silicate dust is processed in the high temperature environment close to the nucleus and transported to outer cooler regions by molecular outflows. The positive correlation between the mass fractions can be naturally explained considering that amorphous pyroxene is transformed from crystalline forsterite by ion bombardments. We also find that spectra with high ratios of the H2O ice absorption to silicate mass column density tend to indicate low mass fractions of amorphous pyroxene and crystalline forsterite, which is consistent with the scenario of the thermal dust processing close to the nucleus.

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Baser, T. A., M. Baricco, S. Enzo, G. Vaughan und A. R. Yavari. „Analysis of crystallization behavior of Fe48Cr15Mo14Y2C15B6 bulk metallic glass by synchrotron radiation“. Journal of Materials Research 23, Nr. 8 (August 2008): 2166–73. http://dx.doi.org/10.1557/jmr.2008.0264.

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The amorphous-to-crystalline transformation behavior of Fe48Cr15Mo14Y2C15B6 bulk metallic glasses was first investigated by high-temperature differential scanning calorimetry. Three events were detected with onset temperatures at 922, 975, and 1036 K, respectively. In situ synchrotron radiation x-ray diffraction patterns were collected during continuous heating and analyzed with the Rietveld approach. To describe simultaneously the amorphous fraction and crystallization products as a function of temperature, a paracrystalline structure-factor model was developed. It was included for quantitative evaluation of the amorphous phase, together with the structure factor of Cr23C6- and Fe3Mo3C-type phases observed during crystallization. Volume fractions of phases as well as lattice parameters, average lattice disorder, and crystallite size of the crystallized phases have been followed as a function of temperature. In this way, the structure evolution and thermal events have been closely inspected and accounted for by a crystallization mechanism.

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MacDonald, Malcolm J., Donna L. Hartley und Marilyn K. Speedie. „Location of cellulolytic enzyme activity in the marine fungus Trichocladium achrasporum“. Canadian Journal of Microbiology 31, Nr. 2 (01.02.1985): 145–48. http://dx.doi.org/10.1139/m85-028.

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Cellulase activity in Trichocladium achrasporum was demonstrated by its ability to produce cell-associated and extracellular cellulolytic enzymes when grown on a crystalline cellulose substrate. In addition, azure dye was solubilized from dyed crystalline cellulose, appearing in the growth medium during the phase of cell lysis. Exoglucanase activity was highest in the culture filtrate, with slight activity in the cell fractions, while endoglucanase was associated only with the mycelium. No desorbable exoglucanase nor endoglucanase activity could be released by sonication of residual cellulose particles removed from actively growing cultures. β-Glucosidase activity was located only in the cell-associated fractions during active growth. All enzymes had optimal activity at 50 °C; in the particulate fraction β-glucosidase exhibited a second optimum at 30 °C. In the filtrate, soluble intracellular and particulate fractions optimal exoglucanase activity occurred at pH 6.4, 7.0, and 5.8, respectively. Endoglucanase activity was optimal at pH 5.8 in the soluble cell fraction, and at pH 5.4 in the particulate fraction.

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Toki, Shigeyuki, Igors Sics, Shaofeng Ran, Lizhi Liu, Benjamin S. Hsiao, Syozo Murakami, Masatoshi Tosaka et al. „Strain-Induced Molecular Orientation and Crystallization in Natural and Synthetic Rubbers under Uniaxial Deformation by In-situ Synchrotron X-ray Study“. Rubber Chemistry and Technology 77, Nr. 2 (01.05.2004): 317–35. http://dx.doi.org/10.5254/1.3547826.

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Abstract In-situ synchrotron wide-angle X-ray diffraction (WAXD) studies and simultaneous measurements of stress and strain during uniaxial stretching of various vulcanized rubbers were carried out (at room temperature and 0°C) to reveal the strain-induced molecular orientation and crystallization relationships. Rubbers evaluated included natural rubber (NR), synthetic poly-isoprene rubber (IR), poly-cis-1,4-butadiene rubber (BR) and butyl rubber (IIR). Some universal features were observed in these systems: (i) At high strains (> 5.0), the majority of the chains (up to 50 ≈ 75%) in natural and synthetic rubbers remained in the un-oriented amorphous state with only a small amount of crystalline fraction formed (10–20%). The rest of the chains were in the oriented amorphous state. (ii) During deformation, the oriented amorphous chains acted as precursors to strain-induced crystallization. A network of micro-fibrillar crystallites is formed within the closely populated vulcanization points, leading to the enhancement of mechanical properties at high strains. Different rubbers exhibited different behaviors during strain-induced crystallization. For example, poly-isoprenes (NR and IR vulcanized with sulfur and peroxide) showed strain-induced crystallization at a low strain of 2.5, resulting in larger crystalline but smaller oriented amorphous fractions. In contrast, BR and IIR crystallized at a higher strain of 4.0 lead to higher molecular orientation, higher oriented amorphous, but smaller crystalline fractions. The relationship between the molecular orientation and crystallization in strained rubber depends on the intrinsic crystallizability of the chains and the topology of the crosslinked network.

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Fraundorf, P., und S. Mukherjee. „Lattice-Image Estimates of Nano-Particle Fraction-Crystalline“. Microscopy and Microanalysis 19, S2 (August 2013): 1590–91. http://dx.doi.org/10.1017/s143192761300994x.

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Gasperini, Antonio, Angelo Malachias, Gilberto Fabbris, Guinther Kellermann, Angelo Gobbi, Esteban Avendaño und Gustavo de Medeiros Azevedo. „Investigation of indirect structural and chemical parameters of GeSi nanoparticles in a silica matrix by combined synchrotron radiation techniques“. Journal of Applied Crystallography 45, Nr. 1 (13.12.2011): 71–84. http://dx.doi.org/10.1107/s0021889811049302.

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The formation of GeSi nanoparticles on an SiO2matrix is studied here by synchrotron-based techniques. The shape, average diameter and size dispersion were obtained from grazing-incidence small-angle X-ray scattering data. X-ray diffraction measurements were used to obtain crystallite sizes and compositionviaresonant (anomalous) measurements. By using these techniques as input for extended X-ray absorption fine structure analysis, the local composition surrounding the Ge atoms is investigated. Although the results for each of the methods above are commonly analyzed separately, the combination of such techniques leads to an improved understanding of nanoparticle structural and chemical properties. Crucial indirect parameters that cannot be quantified by other means are accessed in this work, such as local strain, the possibility of forming core–shell structures, the fraction of Ge atoms diluted in the matrix (not forming nanoparticles), the amorphous and crystalline Ge fractions, and the relative population of nanoparticles with single and multiple crystalline domains.

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Li, Zhi Bin, Ji Wei Hu, Chao Zhou, Yi Miao Lin, Ling Yun Li, Xian Fei Huang und Miao Jia. „Using the Modified Tessier Method to Analyze Antimony Speciation in Suspended Solids in Mining Wastewater“. Advanced Materials Research 955-959 (Juni 2014): 1423–28. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1423.

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The modified Tessier method was used in the present study to analyze the antimony (Sb) speciation in suspended solids in mining wastewater from Ban-po Antimony Mine in Guizhou province. It was found that the residual fraction and the soluble fraction are the highest and the lowest in the five Sb fractions, accounting for 62.5% and 3% of the total respectively. The order of the five Sb fractions is: the residual fraction > the reduced fraction > the oxidation fraction > the acid-extractable fraction > the soluble fraction. The antimony soluble form in aqueous solution is mainly Sb (V), about 90% of the total. The results from the analysis by X-ray diffraction and scanning electron microscopy showed that the major crystalline forms of suspended solids are K-Mg-Fe-Al-Si-O-H2O, Cu3SbS4, 3CaO·2Sb2O5·8H2O, SiO2 and the content of antimony element is approximately 2.55%.

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Arendse, Christopher J., Theophillus F. G. Muller, Franscious R. Cummings und Clive J. Oliphant. „Oxidation Reduction in Nanocrystalline Silicon Grown by Hydrogen-Profiling Technique“. Journal of Nano Research 41 (Mai 2016): 9–17. http://dx.doi.org/10.4028/www.scientific.net/jnanor.41.9.

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The deposition of a compact amorphous silicon/nano-crystalline silicon material is demonstrated by hot-wire chemical vapour deposition using a sequential hydrogen profiling technique at low hydrogen dilutions. Nano-crystallite nucleation occurs at the substrate interface that develops into a uniform, porous crystalline structure as the growth progresses. A further reduction in the H-dilution results in the onset of a dense amorphous silicon layer. The average crystalline volume fraction and nano-crystallite size in the sample bulk amounts to 30% and 6 nm, respectively, as probed by Raman spectroscopy using the 647 nm excitation. The change in hydrogen dilution is accompanied by a graded hydrogen concentration depth-profile, where the hydrogen concentration decreases as the growth progresses. The level of post-deposition oxidation is considerably reduced, as inferred from infrared spectroscopy. The presence of oxygen is mainly confined to the substrate interface as a result of thermal oxidation during thin film growth.

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Dai, Wen Yun, Jing Jin, Chao Xian Hui, Can Liu, Zhi Jun Yuan und Wei Min Shi. „ArF Excimer Laser Assisted Solution Based Metal Induced Crystallization of Amorphous Silicon Films“. Advanced Materials Research 1096 (April 2015): 45–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1096.45.

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Amorphous silicon films with and without spin-coating aluminum-salt-solution are treated by 193nm ArF excimer laser with different laser energies. It is observed that the crystalline fraction increases along with the laser energy. By comparation, with the help of Al, higher crystalline volume fraction and lower in-plane stress can be achieved at the same laser energy (2.9mJ). Large grain size of 200~300nm and maximum crystalline fraction of 82.3% are obtained in Al-salt-solution spin-coated sample, which is treated with laser energy of 3.2mJ,and its carrier mobility is 56.3cm2/Vs.

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Cerqueira, M. Fátima, Margarita Stepikhova, Maria Losurdo, Teresa Monteiro, Manuel J. Soares, Marco Peres, Armando Neves und Eduardo Alves. „Effect of the Matrix on the 1.5μm Photoluminescence of Er-Doped Silicon Quantum Dots“. Materials Science Forum 514-516 (Mai 2006): 1116–20. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1116.

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Erbium doped nanocrystalline silicon thin films were produced by reactive magnetron r.f. sputtering. Their structural and chemical properties were studied by micro-Raman, spectroscopic ellipsometry and Rutherford backscattering spectroscopy. Films with different crystalline fraction and crystallite size were deposited by changing the deposition parameters. The impact of the composition and structure of Erbium ions environment on the 1.5 µm photoluminescence is discussed.

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Krawczyk, Jacek, und Włodzimierz Bogdanowicz. „Solidification Rate Influence on Microstructure of Composites with Quasicrystal Phase Fraction“. Solid State Phenomena 203-204 (Juni 2013): 48–51. http://dx.doi.org/10.4028/www.scientific.net/ssp.203-204.48.

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The composites of Al61Cu27Fe12alloys containing quasicrystalline and crystalline phases (CQ composites) were obtained by the Bridgman method. The morphology of composites crystallized with different solidification rates was studied. The solidification rate influence on fibrous reinforcement morphology was analyzed. The microsections for analysis were prepared parallel and perpendicular to the direction of crystallization. The optical and the scanning electron microscope were used for metallographic observation. Obtained composites were examined by X-ray powder diffraction and reflective X-ray topography. The Laue method enabled to conclude that the matrix is singlecrystalline. The different level of structural perfection of reinforcement fibres was presented at various solidification rates.

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Kemper, F., A. J. Markwick und Paul M. Woods. „The crystalline fraction of interstellar silicates in starburst galaxies“. Monthly Notices of the Royal Astronomical Society 413, Nr. 2 (31.01.2011): 1192–99. http://dx.doi.org/10.1111/j.1365-2966.2011.18204.x.

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Tseng, Lin Yung, Jhewn Kuang Chen, Kai Hung Hsu, Wan Yu Wu und Chi Lung Chang. „Microstructure and Mechanical Properties of Cr-W-B-N Coating Deposited by DC Reactive Magnetron Co-Sputtering“. Advanced Materials Research 651 (Januar 2013): 430–35. http://dx.doi.org/10.4028/www.scientific.net/amr.651.430.

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Nanocomposite Cr-W-B-N coatings with various tungsten contents were synthesized on silicon wafer substrates. The used technique is a DC reactive magnetron co-sputtering deposition equipped with a Cr-B alloy target with 20 at.% B and a W target in a mixed argon/nitrogen plasma atmosphere. Composition and microstructure of the obtained coatings were investigated using X-ray diffraction, X-ray Photoelectron Spectroscope and transmission electron microscope while the micro-hardness was measured using a depth-sensing nano-indenter. The results have shown that the microstructure and the mechanical properties of Cr-W-B-N coatings were strongly dependent on either the tungsten content or the volume fraction of W-N crystalline phases. It was observed that the micro-hardness of Cr-W-B-N coatings is lower than that of Cr-B-N coating as the tungsten content is less than 24 at.% and the volume fraction of W-N crystalline phases is lower than 37 vol.%. As the tungsten content further increased to 30 at.% and the volume fraction of W-N crystalline phases increased to 55 vol.%, the micro-hardness of Cr-W-B-N coating was found enhanced to 19 GPa and higher than Cr-B-N film. It was also obtained that the volume fraction of Cr-N crystalline phases is inversely proportional to the volume fraction of W-N crystalline phases.

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Yang, Changlin, Guanghua Wen, Ping Tang, Chaochao Xi und Qihao Sun. „Quantification of crystalline fraction of solid slag film using X-ray powder diffraction“. Powder Diffraction 31, Nr. 1 (17.02.2016): 40–51. http://dx.doi.org/10.1017/s0885715615000986.

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This paper introduces a new method to determine the crystalline fraction in samples containing amorphous phases from experimental X-ray diffraction data. Computer generated codes, one for each measured data point, are used to interpret the pattern as to where diffraction peaks exist and what is the angular breadth of each peak's intensity above background. Two parameters are defined that are used to identify the position and intensity of the crystalline phase diffraction peaks. For mold fluxes used in continuous casting, the crystalline fraction of solid slag film is a key factor that can affect heat transfer between solidified shell and mold. In this work, a new method was developed to determine the crystallinity of solid slag films. This method does not require structure parameters or other references, and results can be obtained directly by reading a text file with diffraction data. Results indicate that, there is a positive correlation between crystalline fraction and integrated intensities corresponding to crystalline phases. The selection of integration interval does not have much effect on results. To simplify computations, 20–45°2θwas considered as an appropriate interval.

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Abrosimova, G. E., A. S. Aronin und N. N. Kholstinina. „On the determination of the volume fraction of the crystalline phase in amorphous-crystalline alloys“. Physics of the Solid State 52, Nr. 3 (März 2010): 445–51. http://dx.doi.org/10.1134/s1063783410030017.

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SHUMAN, L. M. „COMPARISON OF EXCHANGEABLE Al, EXTRACTABLE Al, AND Al IN SOIL FRACTIONS“. Canadian Journal of Soil Science 70, Nr. 3 (01.08.1990): 263–75. http://dx.doi.org/10.4141/cjss90-028.

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Previous results indicated that the activity of Al3+ in soil solution, Al saturation of the CEC, and 0.01 M CaCl2-extractable Al were related to plant growth. Exchangeable Al values determined by 1 M KCl and 1 M NH4Cl, extractable Al values determined by 1 M NH4OAc, pH 4.8, 0.01 M CaCl2, 0.5 M CuCl2, 0.33 M LaCl3, and 0.005 M NTA, were compared with each other and to the activity of Al3+ in soil solution as well as Al in soil fractions. Aluminum in fractions was measured to determine the forms solubilized by the extradants. The fractions extracted were exchangeable [M Mg(NO3)2], organic bound, Mn oxide, amorphous Fe and Al oxide, and crystalline Fe and Al oxide. The order of Al extracted was CuCl2 > NH4OAc, [Formula: see text]. One M KCl and NH4Cl, and CuCl2, LaCl3, NTA, and NH4OAc, pH 4.8, gave similar relative Al values, especially for topsoils, and were not correlated with CaCl2-Al values. The exchangeable fraction Al [M Mg(NO3)2] was well correlated with the activity of Al3+ in the soil solution and Al saturation of the CEC. Organic fraction Al was negatively correlated with the activity of Al3+ in the soil solution indicating that organic matter can bind Al lowering its concentration in the soil solution. Aluminum in the crystalline Fe/Al oxide fraction correlated well with that extracted by CuCl2, LaCl3, NTA, and NH4OAc, pH 4.8, leading to the possible conclusion that these extradants solubilize Al from plant-unavailable fractions. Key words: Soil aluminum, aluminum extractants, aluminum fractions, exchangeable aluminum

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Nascimento, Clístenes Williams Araújo do, Renildes Lúcio Ferreira Fontes und Adilson César Fortes Dias Melicio. „Copper availability as related to soil copper fractions in oxisols under liming“. Scientia Agricola 60, Nr. 1 (Februar 2003): 167–73. http://dx.doi.org/10.1590/s0103-90162003000100025.

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The knowledge of the chemical forms of copper in soils and the relationships of these forms with soil copper availability are important for predicting the copper behavior in the soil-plant system. The present work studies the influence of liming on the available contents of copper as well as on the forms of copper fractions in six types of Oxisols. Soil samples, with and without liming, received copper at rates of 0.0, 20.0 and 40.0 mg dm-3 and remained incubated for 30 days. Then, available copper was extracted with Mehlich-1, Mehlich-3, DTPA and EDTA solutions, and analyzed by atomic absorption spectrophotometry. Additionally, soil samples were extracted in a sequential procedure to determine Cu in fractions of soil, as follows: exchangeable-Cu fraction, organic matter-Cu fraction, Mn oxide-Cu fraction, amorphous Fe oxide-Cu fraction, crystalline Fe oxide-Cu fraction, residual-Cu fraction, and the total Cu content in the soil. Soil samples to which Cu was added presented higher Cu retention in the organic matter fraction with a small percentage retained in the exchangeable-Cu fraction. Liming resulted in a decrease of Cu in the exchangeable and organic matter fractions and an increase in the Fe and Mn oxide fractions and in the residual fraction. Without liming, the organic matter fraction presented the highest contribution to Cu content found in the soil extracts obtained with all extractors, except EDTA. For treatments with liming, Cu contents in the organic matter fraction were better correlated to Cu contents in extracts obtained with DTPA and Mehlich-3.

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Johnson, J. C., S. P. Ahrenkiel, P. Dutta und V. R. Bommisetty. „Nucleation and Growth of Crystalline Grains in RF-Sputtered TiO2Films“. Research Letters in Nanotechnology 2009 (2009): 1–4. http://dx.doi.org/10.1155/2009/280797.

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AmorphousTiO2thin films were radio frequency sputtered onto siliconmonoxide and carbon support films on molybdenum transmission electron microscope (TEM) grids and observed during in situ annealing in a TEM heating stage at250∘C. The evolution of crystallization is consistent with a classical model of homogeneous nucleation and isotropic grain growth. The two-dimensional grain morphology of the TEM foil allowed straightforward recognition of amorphous and crystallized regions of the films, for measurement of crystalline volume fraction and grain number density. By assuming that the kinetic parameters remain constant beyond the onset of crystallization, the final average grain size was computed, using an analytical extrapolation to the fully crystallized state. Electron diffraction reveals a predominance of the anatase crystallographic phase.

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Kasch, N., I. Dierking, M. Turner, P. Romero-Hasler und E. A. Soto-Bustamante. „Liquid crystalline textures and polymer morphologies resulting from electropolymerisation in liquid crystal phases“. Journal of Materials Chemistry C 3, Nr. 31 (2015): 8018–23. http://dx.doi.org/10.1039/c5tc01639h.

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A small fraction of an acrylate liquid crystalline monomer (≤5%) is mixed into nematic and smectic liquid crystalline phases, and polymerised through the application of a voltage (electropolymerisation).

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Zhou, Ji, Qing-Xin Su, K. M. Moulding und D. J. Barber. „Sol-gel derived Ba(Mg1/3Ta2/3)O3 thin films: Preparation and structure“. Journal of Materials Research 12, Nr. 3 (März 1997): 596–99. http://dx.doi.org/10.1557/jmr.1997.0087.

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Ba(Mg1/3Ta2/3)O3 thin films were prepared by a sol-gel process involving the reaction of barium isopropoxide, tantalum ethoxide, and magnesium acetate in 2-methoxyethanol and subsequently hydrolysis, spin-coating, and heat treatment. Transmission electron microscopy, x-ray diffraction, and Raman spectroscopy were used for the characterization of the thin films. It was shown that the thin films tend to crystallize with small grains sized below 100 nm. Crystalline phase with cubic (disordered) perovskite structure was formed in the samples annealed at a very low temperature (below 500 °C), and well-crystallized thin films were obtained at 700 °C. Although disordered perovskite is dominant in the thin films annealed below 1000 °C, a low volume fraction of 1 : 2 ordering domains was found in the samples and grows with an increase of annealing temperature.

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Kozasa, Takashi, und Hisato Sogawa. „Formation of crystalline silicate around oxygen–rich AGB stars“. Symposium - International Astronomical Union 191 (1999): 239–44. http://dx.doi.org/10.1017/s0074180900203124.

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Crystallization of silicate has been investigated within the framework of dust formation in steady state gas outflows around oxygen–rich AGB stars, where silicates are locked not only into homogeneous silicate grains but also into the mantles of heterogeneous grains. Based on the thermal history of dust grains after their formation, the crystallization calculation results in no crystalline silicate for the mass loss rate Ṁ ≤ 2 × 10−5M⊙ yr−1. Only silicate in the mantles of heterogeneous grains can be crystallized for Ṁ ≥ 3 × 10−5M⊙ yr−1, while homogeneous silicate grains remain amorphous. The mass fraction of crystalline silicate increases with increasing Ṁ. The radiation transfer calculations confirm the appearance of an emission feature around 33.5 μm, taking olivine as a representative of crystalline silicates. On the other hand, the 10μm feature appears in absorption, being dominated by homogeneous silicate grains. These trends are consistent with the observations. Thus the crystalline silicate is a diagnostics of high mass loss rate at the late stage of AGB stellar evolution, reflecting the formation process of dust grains.

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Wang, Ya Jun, Fang Fang Wang und Lian Jie Xu. „Effect of BiCl₃ on the Morphology and Property of PVDF Films“. Advanced Materials Research 804 (September 2013): 74–78. http://dx.doi.org/10.4028/www.scientific.net/amr.804.74.

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Different mass fraction of BiCl3was added into the PVDF film to increase the content ofβ-phase. XRD and SEM were used to analyze the crystalline phase and microstructure of the films. The results show that adding of BiCl3increases the content ofβ-phase in the films. The possible reason of the increment ofβ-phase is that the addition of BiCl3can make the free radicals of PVDF with electric charge return to their original position and consequently improve the degree of crystalline ofβ-phase. Dielectric and thermal properties were also analyzed. When mass fraction of BiCl3is 2%, the PVDF film has the highest degree of crystalline and best properties.

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Khvorostyanov, Vitaly I., und Judith A. Curry. „Analytical Solutions to the Stochastic Kinetic Equation for Liquid and Ice Particle Size Spectra. Part I: Small-Size Fraction“. Journal of the Atmospheric Sciences 65, Nr. 7 (01.07.2008): 2025–43. http://dx.doi.org/10.1175/2007jas2484.1.

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Abstract The kinetic equation of stochastic condensation for cloud drop size spectra is extended to account for crystalline clouds and also to include the accretion–aggregation process. The size spectra are separated into small and large size fractions that correspond to cloud drops (ice) and rain (snow). In Part I of this two-part paper, analytical solutions are derived for the small-size fractions of the spectra that correspond to cloud drops and cloud ice particles that can be identified with cloud liquid water or cloud ice water content, and used in bulk microphysical schemes employed in cloud and climate models. Solutions for the small-size fraction have the form of generalized gamma distributions. Simple analytical expressions are found for parameters of the gamma distributions that are functions of quantities that are available in cloud and climate models: liquid or ice water content and its vertical gradient, mean particle radius or concentration, and supersaturation or vertical velocities. Equations for the gamma distribution parameters provide an explanation of the dependence of the observed spectra on atmospheric dynamics, cloud temperature, and cloud liquid water or ice water content. The results are illustrated with example calculations for a crystalline cloud. The analytical solutions and expressions for the parameters presented here can be used for parameterization of the small-size fraction size spectra in liquid and crystalline clouds and related quantities (e.g., optical properties, lidar, and radar reflectivities).

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Padmanabhan, K. Anantha, und Herbert Gleiter. „On the structure of grain/interphase boundaries and interfaces“. Beilstein Journal of Nanotechnology 5 (22.09.2014): 1603–15. http://dx.doi.org/10.3762/bjnano.5.172.

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Grain/interphase boundaries/interfaces of varying misorientations, free volume fractions, curvatures and irregularities are present in materials, both 3D and 2D, regardless of whether these materials are crystalline or amorphous/glassy. Therefore, a question arises about the central idea on which a general description of grain/interphase boundaries/interfaces can and should be based. It is suggested that a generalized model of a structural/basic unit (crystalline, non-crystalline or of any scale), which depends on the interatomic (including electronic) interactions, the spatial distribution of the atoms and electrons, the number of atoms and free volume fraction present in the structural/basic unit and the experimental conditions should serve the purpose. As the development of a quantitative model, which reflects the effects of all these variables is difficult, slightly defective material boundaries are often modeled by treating the entire boundary as planar and by using the concepts of crystallography. For highly disordered boundaries, a description in terms of a representative volume, made up of a non-crystalline basic unit or a combination of such units, which depend on interatomic (including electronic) interactions and forces, is advocated. The size, shape, free volume fraction and number of atoms in the representative volume could differ with material composition and experimental conditions. In the latter approach, it is assumed that all processes connected to a problem on hand is contained within this representative volume. The unresolved issues are identified.

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Kosmulski, Marek, Edward Mączka und Leszek Ruchomski. „Synthesis and Properties of SBA-15 Modified with Non-Noble Metals“. Colloids and Interfaces 2, Nr. 4 (14.11.2018): 59. http://dx.doi.org/10.3390/colloids2040059.

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Modification of SBA-15 with non-noble metal leads to functional materials, which can be applied as gas sensors, adsorbents, and catalysts of various reactions. The new materials contain up to four various metals, which are deposited consecutively or simultaneously at various concentrations ranging from a fraction of 1% to an amount that is comparable with the mass of silica-support. These materials contain metals at various oxidation levels, usually as oxides, which occur in crystalline form (a typical crystallite size of about 10 nm matches the width of the SBA-15 channels), but in a few other materials, crystalline metal compounds have not been detected. Many researchers have provided detailed physico- chemical characteristics of SBA-15 modified with non-noble metals by the means of various microscopic and spectroscopic techniques.

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Toraya, Hideo. „A new method for quantitative phase analysis using X-ray powder diffraction: direct derivation of weight fractions from observed integrated intensities and chemical compositions of individual phases“. Journal of Applied Crystallography 49, Nr. 5 (16.08.2016): 1508–16. http://dx.doi.org/10.1107/s1600576716010451.

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A new method for the quantitative phase analysis of multi-component polycrystalline materials using the X-ray powder diffraction technique is proposed. A formula for calculating weight fractions of individual crystalline phases has been derived from the intensity formula for powder diffraction in Bragg–Brentano geometry. The integrated intensity of a diffraction line is proportional to the volume fraction of a relevant crystalline phase in an irradiated sample, and the volume fraction, when it is multiplied with the chemical formula weight, can be related to the weight fraction. The structure-factor-related quantity in the intensity formula, when it is summed in an adequate 2θ range, can be replaced with the sum of squared numbers of electrons belonging to composing atoms in the chemical formula. Unit-cell volumes and the number of chemical formula units are all cancelled out in the formula. Therefore, the formula requires only single-measurement integrated intensity datasets for the individual phases and their chemical compositions. No standard reference material, reference intensity ratio or crystal structure parameter is required. A new procedure for partitioning the intensities of unresolved overlapped diffraction lines has also been proposed. It is an iterative procedure which starts from derived weight fractions, converts the weight fractions to volume fractions by utilizing additional information on material densities, and then partitions the intensities in proportion to the volume fractions. Use of the Pawley pattern decomposition method provides more accurate intensity datasets than the individual profile fitting technique, and it expands the applicability of the present method to more complex powder diffraction patterns. Test results using weighed mixture samples showed that the accuracy, evaluated by the root-mean-square error, is comparable to that obtained by Rietveld quantitative phase analysis.

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He, Q., Y. Ren, I. Mohamed, M. Ali, W. Hassan und F. Zeng. „Assessment of trace and heavy metal distribution by four sequential extraction procedures in a contaminated soil“. Soil and Water Research 8, No. 2 (15.05.2013): 71–76. http://dx.doi.org/10.17221/20/2012-swr.

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Four sequential extraction procedures (Sposito, Tessier, Silveira and Bureau Communautaire de Reference (BCR)) were used to evaluate the distribution of some metals (Fe, Cu, Cd and Zn) in a contaminated soil around a mining area. The results showed that Fe and Zn were mainly recovered in the recalcitrant soil fractions, while Cd was primarily localized in the exchangeable fraction. Soil Cu was highly associated with organic matter fraction. The amorphous Fe fraction in Silveira could be recognized as part of the Fe-Mn oxide fraction in Tessier and BCR procedures, while the crystalline Fe oxide fraction was classified into the residual fraction in Sposito, BCR and Tessier schemes. Although the same reagent was used to extract target fraction, less carbonate-bound Cu, Cu and Zn were extracted in Tessier procedure as compared to Silveira method, while Tessier scheme yielded a higher proportion of Fe, Cu and Zn in the Fe-Mn oxide fraction than BCR method. Due to the lack of uniformity of experimental conditions and the differences in extraction reagents, the extraction efficiency of metal species varied with the sequential extraction schemes. Therefore, care should be taken when comparing the results obtained by different sequential extraction procedures.

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Li, Chun Ya, Hao Zhang, Jun Li, Xi Feng Li und Jian Hua Zhang. „The Study of Microcrystalline Silicon Thin Films Prepared by PECVD“. Key Engineering Materials 537 (Januar 2013): 197–200. http://dx.doi.org/10.4028/www.scientific.net/kem.537.197.

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Under different growth conditions, microcrystalline silicon thin films are deposited successfully on glass substrates by the double-frequency plasma enhanced chemical vapor deposition (PECVD). We report the systematic investigation of the effect of process parameters (hydrogen dilution, substrate temperature, forward power, reaction pressure, et al.) on the growth characteristics of microcrystalline silicon thin films. Raman scattering spectra are used to analyze the crystalline condition of the films and the experimental results. Optimizing the process parameters, the highest crystalline volume fraction of microcrystalline silicon films was achieved. It is found that the crystalline volume fraction of microcrystalline silicon films reaches 72.2% at the reaction pressure of 450 Pa, H2/SiH4 flow ratio of 800sccm/10sccm, power of 400 W and substrate temperature of 350 °C.

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Mar’yan, M. I., und N. V. Yurkovych. „Self-Organising Processes and Fractal Approach to the Formation of Non-Crystalline States“. Фізика і хімія твердого тіла 16, Nr. 3 (15.09.2015): 458–63. http://dx.doi.org/10.15330/pcss.16.3.458-463.

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Shows a description of the fractal structure to the non-crystalline state using the system non-linear dynamic equations, which takes into account the flow of negative entropy of the surrounding environment and the fraction of atoms in soft configuratons. Based on the investigation for the study of non-crystalline materials and the transition to non-crystalline state of the possibility fractal approach to describe them.

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Nuth, Joseph A., Hugh G. M. Hill und Gunther Kletetschka. „Determining the ages of comets from the fraction of crystalline dust“. Nature 406, Nr. 6793 (Juli 2000): 275–76. http://dx.doi.org/10.1038/35018516.

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Delgado Rosero, Miguel I., Nori M. Jurado Meneses und Ramiro Uribe Kaffure. „Thermal Properties of Composite Polymer Electrolytes Poly(Ethylene Oxide)/Sodium Trifluoroacetate/Aluminum Oxide (PEO)10CF3COONa + x wt.% Al2O3“. Materials 12, Nr. 9 (07.05.2019): 1464. http://dx.doi.org/10.3390/ma12091464.

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Polymeric membranes of poly(ethylene oxide) (PEO) and sodium trifluoroacetate (PEO:CF3COONa) combined with different concentrations of aluminum oxide (Al2O3) particles were analyzed by impedance spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). DSC results show changes in the crystalline fraction of PEO when the concentration of Al2O3 is increased. TGA analysis showed thermal stability up to 430 K showing small changes with the addition of alumina particles. The decrease in crystalline fraction for membranes with low Al2O3 concentration is associated with the increase in conductivity of (PEO)10CF3COONa + x wt.% Al2O3 composites.

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Demina, Liudmila, Irina Gablina, Olga Dara, Dmitry Budko, Nina Gorkova, Tatiyana Smirnova und Aleksandra Solomatina. „Geochemical Fractions of Heavy Metals in Bottom Sediments of the Pobeda Hydrothermal Field, Mid-Atlantic Ridge (17°07′–17°08′ N)“. Environmental Sciences Proceedings 6, Nr. 1 (25.02.2021): 14. http://dx.doi.org/10.3390/iecms2021-09343.

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We examined the distribution of Fe, Mn, Cu, Zn, and Pb in one core of metalliferous, and one core of non-mineralized (background) carbonate sediments (located 69 km northwards), from the Pobeda hydrothermal field. Mechanisms of metal accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including mobile (exchangeable complex, authigenic Fe-Mn hydroxides, and sulfides), and lithogenic (fixed in crystalline lattices) forms. Maps of element distribution in sediment components were obtained using a scanning electron microscope equipped with an energy-dispersive spectrometry detector. In metalliferous sediments, according to X-ray diffraction data, the main Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis). The contents of Fe and Mn reached 31.6 and 0.18%, respectively, whereas concentrations of Cu, Zn and Pb were 0.98, 0.36, and 0.059%. The coefficient of metal enrichment relative to background values varied from 16 to 125 times. The exception was Mn, for which no increased accumulation was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes. Among geochemically mobile fractions, 90–97% of total Fe was found in the form of authigenic oxyhydroxides. The same fraction was the predominant host for Mn in both metalliferous and background sediments (55–85%). A total of 40–96 % of Cd, Cu, Zn, and Pb were associated with these Fe and Mn fractions. The sulfide fraction amounted to roughly 10% of each metal. In metalliferous sediment core, the maximum concentrations of metals and their geochemically mobile fractions were recorded in deeper core intercepts, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that metals are mostly accumulated in carbonate sediments in their contact zone with the underlying serpentinized basalts.

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Resnina, N., S. Belyaev, V. Slesarenko und A. Shelyakov. „Influence of crystalline phase volume fraction on the two-way shape memory effect in amorphous–crystalline Ti40.7Hf9.5Ni44.8Cu5 alloy“. Materials Science and Engineering: A 627 (März 2015): 65–71. http://dx.doi.org/10.1016/j.msea.2014.12.119.

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Rubinos, D. A., M. Arias, F. Díaz-Fierros und M. T. Barral. „Speciation of adsorbed arsenic(V) on red mud using a sequential extraction procedure“. Mineralogical Magazine 69, Nr. 5 (Oktober 2005): 591–600. http://dx.doi.org/10.1180/0026461056950273.

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AbstractThe distribution of sorbed arsenic(V) among different geochemical fractions for arsenic(V)-loaded red mud, an oxide-rich residue from bauxite refining that has been proposed as an adsorbent for arsenic, was studied as a function of sorbed arsenic(V) concentration using a sequential extraction procedure. The release of previously sorbed arsenic(V) was also studied as a function of pH and arsenic(V) concentration. Most sorbed arsenic(V) (0.39–7.86 mmol kg–1) was associated with amorphous and crystalline Al and Fe oxides (24.1–43.8% and 24.7–59.0% of total sorbed arsenic, respectively). Exchangeable arsenic was the smallest fraction (0.4–5.2% of total sorbed arsenic). The distribution of sorbed arsenic(V) was related to the arsenic surface coverage. For arsenic surface coverages >∼30% the percentage of arsenic(V) associated with the amorphous Al oxide fraction increased and that associated with the crystalline oxide fraction decreased. The arsenic(V) exchangeable fraction increased from 1.4 to 756 μmol kg–1 as surface coverage increased from 388 to 7855 μmol kg–1. The release of sorbed arsenic(V) from red mud was greater at alkaline pH values (maximum release of ∼33% of previously sorbed arsenic at pH = 12), but for high arsenic(V) initial concentration (0.2 mM arsenic) considerable amounts of arsenic (6.5% of previously sorbed arsenic) were released at pH 4, in accordance with the dissolution of amorphous Al oxides in the red mud. The results obtained suggest a greater mobility of sorbed arsenic(V) as its surface concentration approaches saturation.

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Abdulvaliyev, R. A., S. B. Dyussenova, A. I. Manapova, A. Akcil und U. Zh Beisenbiyeva. „Modification of the phase composition of low-grade gibbsite-kaolinite bauxites“. Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 317, Nr. 2 (15.06.2021): 94–102. http://dx.doi.org/10.31643/2021/6445.22.

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The known methods of processing low-quality bauxite have a number of disadvantages that make it difficult or impossible to use them in the conditions of production of JSC "Aluminum of Kazakhstan", therefore, it is necessary to effectively develop a technology for preliminary enrichment. Enrichment of low-quality bauxites is possible by separating the clayey - high-siliceous and coarse-crystalline fractions. Electron-microscopic analysis of the original bauxite showed that the coarse-crystalline fraction is tightly pressed by the fine one. The total silicon modulus of the sample is 2.49. The silicon modulus of the fine fraction is 2.19, and that of the coarse fraction is 3.89. When enriching bauxite, as a result of the separation of fines, it is possible to increase the silicon modulus. After the chemical activation of bauxite in a sodium bicarbonate solution, the finely dispersed fraction is effectively separated from the coarse one and the phase composition changes - the calcium silicate phase disappears and the calcite phase is formed. With an increase in the activation temperature, the content of kaolinite and siderite decreases, and the content of quartz and hematite increases. Studies have shown that at temperatures of chemical activation of 120 ° C, duration of more than 120 minutes and 200 ° C, duration of more than 40 minutes, a dawsonite phase is formed in bauxite, which densifies the mineral structure. When determining the optimal regime for carrying out chemical activation, it is necessary to take into account the negative possibility of dawsonite formation.

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Cevik, Ismail, und Suat U. Ay. „A Low-Power and Low-Voltage Power Management Strategy for On-Chip Micro Solar Cells“. Journal of Sensors 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/739871.

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Fundamental characteristics of on-chip micro solar cell (MSC) structures were investigated in this study. Several MSC structures using different layers in three different CMOS processes were designed and fabricated. Effects of PN junction structure and process technology on solar cell performance were measured. Parameters for low-power and low-voltage implementation of power management strategy and boost converter based circuits utilizing fractional voltage maximum power point tracking (FVMPPT) algorithm were determined. The FVMPPT algorithm works based on the fraction between the maximum power point operation voltage and the open circuit voltage of the solar cell structure. This ratio is typically between 0.72 and 0.78 for commercially available poly crystalline silicon solar cells that produce several watts of power under typical daylight illumination. Measurements showed that the fractional voltage ratio is much higher and fairly constant between 0.82 and 0.85 for on-chip mono crystalline silicon micro solar cell structures that produce micro watts of power. Mono crystalline silicon solar cell structures were observed to result in better power fill factor (PFF) that is higher than 74% indicating a higher energy harvesting efficiency.

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Sorescu, Monica, und Kevin Byerly. „Nanocrystallization and Recoilless Fraction Determination of Fe68.5Co5Nb3Cu1Si15.5B7 Ferromagnetic Alloy“. MRS Advances 4, Nr. 25-26 (2019): 1449–55. http://dx.doi.org/10.1557/adv.2019.34.

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ABSTRACTAmorphous alloy Fe68.5Co5Nb3Cu1Si15.5B7 was obtained by melt spinning. Samples cut from the foil were annealed at 450, 550, 650 and 750 °C in a vacuum furnace. 57Fe Mӧssbauer spectroscopy was used to identify the crystalline phases formed and the orientation of the magnetic moments based on the refined values of the hyperfine parameters. The spectra of the samples annealed at 550, 650 and 750 °C were indicative of nanocrystallization, with the magnetic moments reoriented out-of-plane for the last sample. This behavior is in contradistinction to that of the Co-rich system, which was totally crystallized at these annealing temperatures. Our results show that small Co additions can lead to the formation of nanostructures over a whole range of annealing temperatures. A new series of Mӧssbauer spectra was obtained by recording simultaneously the intensity transmitted by a superposition of the sample with the stainless steel etalon, based on the dual absorber method previously introduced by us. The values of the recoilless fraction could be derived from the relative spectral areas. The f factor maintained values close to 0.7 for all samples measured, but dropped to 0.37 for the sample annealed at 750 °C. This behavior could be related to the presence of elastic stresses in the system, which caused the out-of-plane reorientation of the magnetic moment directions.

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Vepřek, S., F. A. Sarott und M. Rückschloß. „Temperature dependence of the crystallite size and crystalline fraction of microcrystalline silicon deposited from silane by plasma CVD“. Journal of Non-Crystalline Solids 137-138 (Januar 1991): 733–36. http://dx.doi.org/10.1016/s0022-3093(05)80225-x.

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Hefland, R. B., P. E. Schwarzel, B. V. Johansen, T. Myran, N. Uthus und M. Refsnes. „Silica-induced cytokine release from A549 cells: importance of surface area versus size“. Human & Experimental Toxicology 20, Nr. 1 (Januar 2001): 46–55. http://dx.doi.org/10.1191/096032701676225130.

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Physical and chemical properties such as structure, composition and surface reactivity determine the biological activity of mineral particles. Long-term exposureto crystalline silica is known to cause persistent pulmonary inflammation leading to adverse health effects. There is less information about the potential health effects of amorphous (noncrystal-line) silica. In this study, the inflammatory and cytotoxic potency of crystalline and amorphous silica in relation to particle size and surface area was assessed. Human epithelial lung cells (A549) were exposed to different size fractions of quartz (aerodynamic diameter 0.5,2 and 10 sm) and amorphous silica (diameter 0.3 pm). All particles induced increased release ofthe proinflammatory cytokines interleukin (IL)-6 and IL-8. When cells were exposed to equal masses of quartz, the smallest size fraction was the most potent. These differences, however, disappeared when cytokine release was related to equal surface areas. When amorphous silica and quartz were compared, the amorphoussilicawas mostpotentto induce IL-6 regardless of how exposure was expressed, whereas the smallest size fraction of quartz was the most potent inducer of IL-8. Thus, the surface area seems to be the critical determinant when potency of different sizes of quartz is compared.

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Jiang, Biwei, Jiaming Liu und Aigen Li. „Are the silicate crystallinities of oxygen-rich evolved stars related to their mass loss rates?“ Proceedings of the International Astronomical Union 14, S343 (August 2018): 425–26. http://dx.doi.org/10.1017/s174392131800697x.

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AbstractA sample of 28 oxygen-rich evolved stars is selected based on the presence of crystalline silicate emission features in their ISO/SWS spectra. The crystallinity, measured as the flux fraction of crystalline silicate features, is found not to be related to mass loss rate that is derived from fitting the spectral energy distribution.

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Krzanowski, James E., T. Taylor Eighmy, Bradley S. Crannell und J. Dykstra Eusden. „An analytical electron microscopy investigation of municipal solid waste incineration bottom ash“. Journal of Materials Research 13, Nr. 1 (Januar 1998): 28–36. http://dx.doi.org/10.1557/jmr.1998.0005.

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Incinerator bottom ash samples have been characterized using analytical electron microscopy (AEM) techniques, including electron diffraction, energy dispersive spectroscopy, and electron energy loss spectroscopy. The samples were first separated by magnetic properties and density. Three resulting fractions were examined: the magnetic, high-density (MHD) fraction, the nonmagnetic/high-density (NMHD) fraction, and the nonmagnetic, low-density (NMLD) fraction. Examination of these samples revealed a variety of submicron microstructural features. For the MHD fraction, metal oxides, iron silicates, aluminum silicates, and calcium phosphate compounds were found in addition to amorphous material. The NMHD fraction contained elements similar to the MHD fraction but had more amorphous material; crystalline silicates were less common. Compounds such as MgO and chloroapatite were also found. The NMLD fraction contained SiO2 and numerous metal oxides. The results of some of these analyses were used to model leaching behavior of the ash. Based on the AEM results, three mineral phases were chosen as candidates for aqueous geochemical thermodynamic equilibrium modeling of pH-dependent leaching: chromite, chloroapatite, and zincite. In two of these three cases (chromite, chloroapatite), the selected mineral phase provided excellent agreement with the experimentally observed leaching behavior. AEM was shown to be a useful tool for elucidating mineralogy of complex environmental samples.

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Zhang, Ying Chao. „Hydrothermal Synthesis of Ni-Fe Layered Double Hydroxide with High Crystallinity Using Homogeneous Precipitation Method“. Advanced Materials Research 821-822 (September 2013): 1313–16. http://dx.doi.org/10.4028/www.scientific.net/amr.821-822.1313.

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Ni-Fe layered double hydroxide containing carbonate anion (CO32- ) has been successfully synthesized by a process of homogeneous precipitation involving urea hydrolysis under hydrothermal conditions. Factors that influence the composition and the crystallinity degree of NiFe-LDH, such as the molar fraction of urea/NO3- in solution, the total metal ion concentration in solution and the aging time, have been investigated in detail. Structure and morphology of the sample were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectra and scanning electron microscope (SEM). The results indicate NiFe-LDH with high purity present well-crystalline, uniform crystallite size

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Jiang, Wenbiao, M. Grant Norton, Lancy Tsung und J. Thomas Dickinson. „Pulsed-laser deposition of polytetrafluoroethylene“. Journal of Materials Research 10, Nr. 4 (April 1995): 1038–43. http://dx.doi.org/10.1557/jmr.1995.1038.

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Thin films of polytetrafluoroethylene have been deposited on amorphous substrates by the pulsed-laser deposition technique. By transmission electron microscopy, the polymer films were shown to consist of both amorphous and crystalline components. The data for the crystalline component are consistent with it being highly ordered with the long helical molecular chains aligned parallel to the film substrate interface plane. The fraction of crystalline material in the films was found to be related to the substrate temperature during deposition with the maximum amount of crystalline material occurring when the substrate temperature was close to the melting temperature of the polymer.

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