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  1. EFFECT OF MgO ON THE COMPOSITION AND PROPERTIES OF BELITE-BARIUM CALCIUM SULPHOALUMINATE CEMENT IN THE PRESENCE OF Na2O AND K2O

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    Jie Zhang

    2015-06-01

    Full Text Available The purpose of this study is to explore the effect of MgO (1 - 9 wt. % on the composition and properties of belite-barium calcium sulphoaluminate cement with additions of Na2O and K2O. The results show that 1 - 5 wt. % content of MgO can stabilize crystal types of M3-C3S, R-C3S and β-C2S. Moreover, MgO can promote the formation of C3S and C4AF, but has little effect on the formation of C2.75B1.25A3$ and C3A. The C3A/C4AF ratio is reduced by 22 % at 5 wt. % MgO, which indicates that appropriate MgO can decrease the liquid viscosity. In the presence of Na2O and K2O, the highest limit of incorporated amount of MgO is about 3 wt. %, which is higher than that in Portland cement clinker of 2 wt. %. Besides, MgO favors the formation of small C3S crystals in size of 4 - 20 μm. MgO enhances the hydration rate and mechanical property of cement at an optimal dosage (1 - 5 wt. %, beyond which an adverse effect could be resulted. At a MgO dosage of 5 wt. %, the compressive strengths of the cement at 1, 3, 7 and 28 days are 15.8, 39.3, 68.6 and 97.3 MPa, which increases by 116 %, 17 %, 10 % and 6 % respectively compared to the cement without MgO dopant. This study could lead to the effective use of magnesia-rich limestone in industrial production of belite-barium calcium sulphoaluminate cement.

  2. On the magnetic properties of B2O3-Pbo-Fe2O 3-K2O and B2O3-PbO-Fe 2O3-CaO glasses

    OpenAIRE

    Burzo, E.; Ungur, D.; Ardelean, I.

    1983-01-01

    The 20 Fe2O380[3 B2O3(1 - x)PbOxAuOv,] glasses with A uOv = K2O and CaO were studied by magnetic and Mössbauer effect measurements. The variation of the fraction r of ferrous ions is proportional to the difference between the valence of A ions and that of lead as well as to AuOv content. The composition dependence of r values is analysed in correlation with the glass composition.

  3. Liquidus of the HfO2-MgO and HfO2-CaO systems

    International Nuclear Information System (INIS)

    Studied is the liquidus of the HfO2-MgO and HfO2-CaO systems by the method of the thermal analysis using solar heating. The liquidus of the HfO2-MgO system is stated to be of eutectic type. The liquidus of the HfO2-CaO system is characterized by the presence of two eutectic points. The maximum on the liquidus at the temperature of 2440+-25 deg C meets the formation of the CaHfO3 compounds

  4. CAOS

    DEFF Research Database (Denmark)

    Erdman Thomsen, Hanne; Madsen, Bodil Nistrup

    2011-01-01

    This paper presents some principles of terminological ontologies implemented in the prototype that has been developed in the research project CAOS - Computer-Aided Ontology Structuring. Furthermore, some issues that have to be faced to further develop facilities for automatic consistency checking...... and automatic changes to ontologies, are discussed. The presentation will illustrate central facilities of the current version of the CAOS prototype, which is interactive and presupposes an end-user with a background in terminology rather than in formal ontology....

  5. Study of solid state interactions in the systems ZnFe2O4 - CaO, ZnFe2O4 - MgO and zinc cake with CaO and MgO

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    Peltekov A.B.

    2013-01-01

    Full Text Available The solid state interactions of CaO and MgO with synthetic and industrial ZnFe2O4 (in zinc cake have been studied using chemical, XRD analysis and Mössbauer spectroscopy. The exchange reactions in the systems ZnFe2O4 - CaO and ZnFe2O4 - MgO have been investigated in the range of 850-1200ºC and duration up to 180 min. It has been established that Ca2+ and Mg2+ ions exchange Zn2+ in ferrite partially and the solubility of zinc in a 7% sulfuric acid solution increases. The possibilities for utilization of the obtained results in zinc hydrometallurgy have been discussed.

  6. Opposite rumpling of the MgO and CaO (100) surfaces: A density-functional theory study

    International Nuclear Information System (INIS)

    Density-functional theory calculations using the periodic slab approach are carried out to investigate the relaxed structures of the regular MgO and CaO(100) surfaces. Both local density and gradient corrected approximations to the exchange-correlation energy are employed and slab orbitals are expanded in Gaussian atom-centered orbitals as well as in plane waves. For MgO, the cations are displaced downwards towards the bulk relative to the oxygens with surface rumpling of ca. 2%. The vertical displacements of the atoms in CaO are in the opposite direction, producing a rumple of ca. -0.5%. It is suggested that the opposite rumpling is driven by steric effects, i.e., by the larger size of calcium cations relative to magnesium cations. (c) 2000 The American Physical Society

  7. Studies on Thermophysical Properties of CaO and MgO by γ-Ray Attenuation

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    A. S. Madhusudhan Rao

    2014-01-01

    Full Text Available The study on temperature dependent γ-ray attenuation and thermophysical properties of CaO and MgO has been carried out in the temperature range 300 K–1250 K using different energies of γ-beam, namely, Am (0.0595 MeV, Cs (0.66 MeV, and Co (1.173 MeV and 1.332 MeV on γ-ray densitometer fabricated in our laboratory. The linear attenuation coefficients (μl for the pellets of CaO and MgO as a function of temperature have been determined using γ-beam of different energies. The coefficients of temperature dependence of density have been reported. The variation of density and linear thermal expansion of CaO and MgO in the temperature range of 300 K–1250 K has been studied and compared with the results available in the literature. The temperature dependence of linear attenuation coefficients, density, and thermal expansion has been represented by second degree polynomial. Volume thermal expansion coefficients have been reported.

  8. Overcoming the polarization catastrophe in the rocksalt oxides MgO and CaO

    Science.gov (United States)

    Gaddy, Benjamin E.; Paisley, Elizabeth A.; Maria, Jon-Paul; Irving, Douglas L.

    2014-09-01

    Interfaces between dissimilar polar materials may provide a pathway to new device functionality, including high carrier mobility layers at the interface. The development of these materials has proven challenging, in part because of the high energy cost of forming polar surfaces. Our density functional theory calculations explore the mechanisms by which a real material satisfies the electrostatic criteria for stability imposed by a polar surface. The consequences of polarity are studied by comparing the formation energies, charge distribution, and electronic structure of a number of low-index surfaces of rocksalt MgO and CaO. These surfaces are explored both in their bare, undecorated form as well as with surface reconstructions and adsorbed foreign species. Our ground-state surface energies are extended to relevant environmental conditions by use of ab initio thermodynamics. We find that the high energy of bare polar surfaces is the result of the significant charge redistribution that arises to compensate the polarity and pushes electronic states into the forbidden band gap. Other mechanisms of polarity compensation (reconstruction or foreign species adsorption) are therefore seen more frequently. We explain the experimental observations of surface roughness during growth in the [111] direction. In typical epitaxial growth conditions, there is preferential formation of an octopolar reconstruction of the {111} surface, which exposes {001}-type nanofacets. The low energy of the {001} surface likely causes these facets to grow, leading to a rough surface morphology. Our results indicate that when water vapor is present during growth, a smooth, polar surface can be stabilized by the formation of a hydroxyl layer.

  9. Experimental investigation and thermodynamic modeling of the (NiO + CaO + SiO2), (NiO + CaO + MgO) and (NiO + CaO + MgO + SiO2) systems

    International Nuclear Information System (INIS)

    Highlights: • Thermodynamic optimization of the (NiO + CaO + SiO2) and (NiO + CaO + MgO + SiO2) system. • Phase equilibria studied by equilibration, quenching and EPMA. • A set of self-consistent Gibbs free energy functions of all phases was obtained. • All phase equilibria and thermodynamic data are reproduced within experimental error limits. • This is the basis for a thermodynamic database for simulation of nickel extraction from ores. - Abstract: The (NiO + CaO + MgO + SiO2) system and its ternary subsystems (NiO + CaO + MgO) and (NiO + CaO + SiO2) have been studied by a combination of thermodynamic modeling and experimental measurements of phase equilibria. A complete literature review and critical evaluation of phase diagrams and thermodynamic properties of all oxide phases in these systems at 1 atm total pressure are presented. To resolve the contradictions in the literature data for the (NiO + CaO + SiO2) system, a new experimental investigation has been carried out over the temperature range from (1330 to 1500) °C using an equilibration and quenching technique followed by electron probe X-ray microanalysis (EPMA). The compositions of phases for equilibria among liquid, pseudo-wollastonite, clino-pyroxene, olivine and tridymite have been measured. The whole set of experimental data, including the new experimental results and previously published data, is taken into consideration in thermodynamic modeling of oxide phases and optimization of model parameters. The Modified Quasichemical Model is used for the liquid phase. The models for olivine, melilite and pyroxene solid solutions are developed within the framework of the Compound Energy Formalism. A self-consistent set of thermodynamic functions of all phases in the (NiO + CaO + MgO + SiO2) system is obtained, which reproduces all available thermodynamic and phase diagram data within experimental error limits

  10. Biodiesel Production From the Microalgae Nannochloropsis by Microwave Using CaO and MgO Catalysts

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    Herman Hindarso

    2015-02-01

    Full Text Available The needs of world petroleum are increased; in contrast, the fuel productions are getting decreased. Therefore, it has lead to the search for bio-fuel as an alternative energy. There are several different types of biofuel, such as biodiesel, ethanol, bioalcohol, and biogas. Biodiesel is typically made by chemically reacting lipids from a vegetable oil or animal fat with an alcohol producing fatty acid esters, such as methyl or ethyl ester. The present study aimed to study the effect of temperature (50, 60 and 65°C, reaction time (1 to 5 minutes dan types of catalyst (CaO dan MgO of 1 and 3 % in the production of biodiesel from microalgae by the transesterification process using microwave methods. It also studied the characteristics of biodiesel which had the greatest yield in the present study, i.e. flash point, cetane number, density, viscosity, and FAME. The greatest yield was 99.35% and obtained with combination of 3% MgO catalyst quantity at temperature of 60°C, in 3 minutes reaction time. At this process conditions, the biodiesel has a flash point of 122°C, cetane number of 55, density of  0.89, viscosity of 5 cP and FAME of 75.12 %.

  11. Role of Y{sub 2}O{sub 3}, CaO, MgO additives on structural and microstructural behavior of zirconia/mullite aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, D. K.; Prusty, Sasmita; Mohapatra, B. K.; Singh, S. K.; Behera, S. N. [Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); Geological Survey of India, Alandi Road, Pune 411 006, Maharashtra (India); Mineralogy Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751 013, Odisha (India); National Institute of Science and Technology (NIST), Berhampur 761 008, Odisha (India)

    2012-07-23

    Zirconia mullite (MUZ), Y{sub 2}O{sub 3}-MUZ, CaO-MUZ and MgO-MUZ composites, synthesized through plasma fusion technique, are becoming important due to their commercial scale of production within five minutes of plasma treatment from sillimanite, zircon and alumina mixture. The X-ray diffraction studies reveal the monoclinic zirconia phase in MUZ composite whereas mixed monoclinic, tetragonal and cubic phases of zirconia have been observed in Y{sub 2}O{sub 3}, CaO, MgO added MUZ composites. The Y{sub 2}O{sub 3}, CaO and MgO additives act as sintering aids to favour the transformation and stabilisation of tetragonal and cubic zirconia phases at room temperature. These additives also play a key role in the development of various forms of microstructure to achieve dense MUZ composites.

  12. Quantitative evaluation of antibacterial activities of metallic oxide powders (ZnO, MgO and CaO) by conductimetric assay.

    Science.gov (United States)

    Sawai, J

    2003-08-01

    Antibacterial activities of metallic oxide (ZnO, MgO and CaO) powders against Staphylococcus aureus and Escherichia coli were quantitatively evaluated by measuring the change in electrical conductivity of the growth medium caused by bacterial metabolism (conductimetric assay). The obtained conductivity curves were analyzed using the growth inhibition kinetic model proposed by Takahashi for calorimetric evaluation, and the metallic oxides were determined for the antibacterial efficacy and kinetic parameters. The parameters provide some useful indicators for antimicrobial agents, such as the dependence of antibacterial activity on agent concentration, and the affinity between the agent and the bacterial cells. CaO was the most effective, followed by MgO and ZnO, against E. coli. On the other hand, ZnO was the most effective for S. aureus and was suggested to have a strong affinity to the cells of S. aureus. PMID:12782373

  13. Role of Y2O3, CaO, MgO additives on structural and microstructural behavior of zirconia/mullite aggregates

    International Nuclear Information System (INIS)

    Zirconia mullite (MUZ), Y2O3-MUZ, CaO-MUZ and MgO-MUZ composites, synthesized through plasma fusion technique, are becoming important due to their commercial scale of production within five minutes of plasma treatment from sillimanite, zircon and alumina mixture. The X-ray diffraction studies reveal the monoclinic zirconia phase in MUZ composite whereas mixed monoclinic, tetragonal and cubic phases of zirconia have been observed in Y2O3, CaO, MgO added MUZ composites. The Y2O3, CaO and MgO additives act as sintering aids to favour the transformation and stabilisation of tetragonal and cubic zirconia phases at room temperature. These additives also play a key role in the development of various forms of microstructure to achieve dense MUZ composites.

  14. The solubilities of BeO, MgO and CaO in molten LiF-NaF-KF eutectic

    International Nuclear Information System (INIS)

    The solubilities of BeO, MgO and CaO in molten LiF-NaF-KF eutectic were determined at the temperatures between 600 and 800 deg C. The dissolution equilibrium of these oxides was found to be reached after a week of equilibration at 600 deg C. The heat of solutions, ΔH, obtained were (2.89 ± 0.17) x 10-4, (2.72 ± 0.25) x 10-4 and (2.09 ± 0.21) x 10-4 J/mol for BeO, MgO and CaO, respectively. The solubilities were markedly affected by the residual oxide ion concentration in the eutectic. (author)

  15. Secondary ionization coefficient γ of MgO, SrO and CaO and the correlation between γ and charge accumulated on CaO in argon

    Science.gov (United States)

    Suzuki, S.; Itoh, H.

    2014-12-01

    An experimental investigation of Townsend's secondary ionization coefficient γ is carried out for MgO, SrO and CaO film electrodes. These oxides are utilized, or are to be utilized, in next-generation plasma display panels. All of the experiments are performed in argon. In particular, in the case of CaO film, our attention is attracted to the effect of charge accumulated on CaO film. For this purpose, the breakdown voltage Vs is observed from waveforms of the gap voltage and charge accumulated on the dielectric film electrodes with the repeated breakdown. Townsend's criterion is utilized to estimate γ from the breakdown voltage. In the case of the CaO film, γ increases gradually with repeated breakdowns and reaches a stationary value. The increase of γ is considered to be due to the charge that accumulates on the dielectric electrode triggering the next breakdown. Therefore, it is concluded that the increased γ is sustained by a combined process consisting of restarted electrons that have accumulated on the CaO film and the original γ action, as observed in metallic electrodes in a low-pressure gas discharge.

  16. Secondary ionization coefficient γ of MgO, SrO and CaO and the correlation between γ and charge accumulated on CaO in argon

    International Nuclear Information System (INIS)

    An experimental investigation of Townsend's secondary ionization coefficient γ is carried out for MgO, SrO and CaO film electrodes. These oxides are utilized, or are to be utilized, in next-generation plasma display panels. All of the experiments are performed in argon. In particular, in the case of CaO film, our attention is attracted to the effect of charge accumulated on CaO film. For this purpose, the breakdown voltage Vs is observed from waveforms of the gap voltage and charge accumulated on the dielectric film electrodes with the repeated breakdown. Townsend's criterion is utilized to estimate γ from the breakdown voltage. In the case of the CaO film, γ increases gradually with repeated breakdowns and reaches a stationary value. The increase of γ is considered to be due to the charge that accumulates on the dielectric electrode triggering the next breakdown. Therefore, it is concluded that the increased γ is sustained by a combined process consisting of restarted electrons that have accumulated on the CaO film and the original γ action, as observed in metallic electrodes in a low-pressure gas discharge. (paper)

  17. Biological and mechanical properties of an experimental glass-ionomer cement modified by partial replacement of CaO with MgO or ZnO

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    Dong-Ae KIM

    2015-08-01

    Full Text Available AbstractSome weaknesses of conventional glass ionomer cement (GIC as dental materials, for instance the lack of bioactive potential and poor mechanical properties, remain unsolved.Objective The purpose of this study was to investigate the effects of the partial replacement of CaO with MgO or ZnO on the mechanical and biological properties of the experimental glass ionomer cements.Material and Methods Calcium fluoro-alumino-silicate glass was prepared for an experimental glass ionomer cement by melt quenching technique. The glass composition was modified by partial replacement (10 mol% of CaO with MgO or ZnO. Net setting time, compressive and flexural properties, and in vitrorat dental pulp stem cells (rDPSCs viability were examined for the prepared GICs and compared to a commercial GIC.Results The experimental GICs set more slowly than the commercial product, but their extended setting times are still within the maximum limit (8 min specified in ISO 9917-1. Compressive strength of the experimental GIC was not increased by the partial substitution of CaO with either MgO or ZnO, but was comparable to the commercial control. For flexural properties, although there was no significance between the base and the modified glass, all prepared GICs marked a statistically higher flexural strength (p<0.05 and comparable modulus to control. The modified cements showed increased cell viability for rDPSCs.Conclusions The experimental GICs modified with MgO or ZnO can be considered bioactive dental materials.

  18. Effects of CaO, Al2O3 and MgO on liquidus temperatures of copper smelting and converting slags under controlled oxygen partial pressures

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    Zhao B.

    2013-01-01

    Full Text Available Phase equilibria of silicate slags relevant to the copper smelting/converting operations have been experimentally studied over a wide range of slag compositions, temperatures and atmospheric conditions. Selected systems are of industrial interest and fill the gaps in fundamental information required to systematically characterise and describe copper slag chemistry. The experimental procedures include equilibration of synthetic slag at high temperatures, rapid quenching of resulting phases, and accurate measurement of phase compositions using electron probe X-ray microanalysis (EPMA. The effects of CaO, Al2O3 and MgO on the phase equilibria of this slag system have been experimentally investigated in the temperature range 1200 to 1300 oC and oxygen partial pressures between 10-5 and 10-9 atm. It was found that spinel and silica are major primary phases in the composition range related to copper smelting/converting slags. In addition, olivine, diopside and pyroxene also appear at certain conditions. The presence of CaO, MgO and Al2O3 in the slag increases the spinel liquidus and decreases the silica liquidus. Liquidus temperatures in silica primary phase field are not sensitive to Po2; Liquidus temperatures in spinel primary phase field increase with increasing Po2. At 1300 oC and low Po2, the spinel (Fe2+,Mg2+O.(Al3+,Fe3+ primary phase field can be replaced by wustite (Fe2+,Mg2+O.

  19. Oxygen vacancies and peroxo groups on regular and low-coordinated sites of MgO, CaO, SrO, and BaO surfaces

    Science.gov (United States)

    Di Valentin, Cristiana; Ferullo, Ricardo; Binda, Riccardo; Pacchioni, Gianfranco

    2006-03-01

    The formation of an oxygen vacancy and the simultaneous re-adsorption of an oxygen atom on regular and low-coordinated (LC) sites (edges and corners) of the surface of alkaline-earth oxides with cubic rock salt structure, MgO, CaO, SrO, and BaO, has been investigated using DFT cluster model calculations. The process corresponds to the formation of a surface Frenkel defect when the vacancy formation energy is partially compensated by the energy gained in the formation of a peroxo group. The structural and electronic properties of vacancies and peroxo groups along the series of alkaline-earth oxides have been analyzed. We found that the role of low-coordinated sites on the surface chemistry of alkaline-earth oxides is of crucial importance for MgO, but decreases for the heavier members. For instance, on BaO the formation of a peroxo group is practically site-insensitive. This is not the case of the vacancy formation, which is always favored on the low-coordinated sites.

  20. CO adsorption on Ni, Pd, Cu and Ag deposited on MgO, CaO, SrO and BaO: Density functional calculations

    International Nuclear Information System (INIS)

    The adsorption properties of CO molecules adsorbed on Ni, Pd, Cu and Ag atoms deposited on O2-, F and F+ sites of MgO, CaO, SrO and BaO terrace surfaces have been studied by means of density functional calculations and embedded cluster model. The examined clusters were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The adsorption properties of CO have been analyzed with reference to the basicity of the oxide support, bond order conservation energy, pairwise and non-pairwise additivity, associative adsorption, electrostatic potentials, and orbital interactions. CO adsorption on an oxide support is drastically enhanced when CO is adsorbed on a metal deposited on this support. A dramatic change is found, and explained, when one compares the CO binding energy to O2- and F sites. The formation of a strong bond at the support-metal interface has a considerable consequence on the metal-CO binding energy. The binding of CO is dominated by the metal-CO pairwise additive term, and the non-additivity term increases with increasing the basicity of the support. While the classical contributions to the electrostatic interactions are quite similar for the deposited metals, they are quite dissimilar when going from defect-free to defect-containing surfaces. The adsorption properties correlate linearly with the basicity and energy gaps of the oxide support where the electrostatic potential generated by the oxide modifies the physical and chemical properties of the adsorbed metal and therefore its reactivity versus the CO adsorbate.

  1. Dielectric study of refractory oxides (ZrO/sub 2/ - MgO - CaO - Al/sub 2/O/sub 3/

    International Nuclear Information System (INIS)

    The dielectric characteristics of CaAl/sub 2/O/sub 4/ doped MgO stabilized zirconia is studied. Pellets sintered at 1600 deg. C of CaZrO/sub 3/-MgO doped with 0,1,2,3, and 4 mole percent of CaAl/sub 2/O/sub 4/ were prepared Bridge balance method was used for the dielectric studies. Dielectric constant was found to increase by the increase of temperature or decrease of frequency. The increase of dopant CaAl/sub 2/O/ sub 4/ concentration also caused the dielectric constant to decrease, producing its lowest value at 13.27 for 3 mol.5 concentration of dopant. (author)

  2. Effects of CaO, MgO, Al2O3 and SiO2 on the carbothermic reduction of synthetic FeCr2O4

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    Wang Y.

    2015-01-01

    Full Text Available In order to optimize the current reduction process of chromite, a good knowledge of reduction mechanism involved is required. The basic component in chromite ore is FeCr2O4 with gangue component like MgO and Al2O3. In lack of clear and consistent explanation about the effect of addition on the reduction of FeCr2O4, investigation of synthetic FeCr2O4 with different kind and amount of additions was carried out at 1673K under isothermal mode. Kinetic mechanism was also studied by linear fitting of different kinetic equations. Combined with rate-controlling step, it could be concluded as follows. CaO could enhance the reduction because Ca2+ would replace Fe2+, thus facilitated the ion diffusion in solid phase. Al2O3 had a positive influence as well, since Al3+ could form a solid solution phase with Cr3+ and made Cr3+ reduced more easily. MgO would hinder the reduction due to formation of a more stable phase MgCr2O4. SiO2 would also hamper the Cr metallization because there was a liquid phase formed when Cr3+ was reduced to divalent, which would impede the nucleation of reduction product.

  3. Performance of CaO and MgO for the hot gas clean up in gasification of a chlorine-containing (RDF) feedstock.

    Science.gov (United States)

    Corella, José; Toledo, José M; Molina, Gregorio

    2008-11-01

    Calcined limestone (CaO) and calcined dolomite (CaO.MgO) were tested at bench scale to study their usefulness in cleaning hot raw gas from a fluidized bed gasifier of a synthetic or simulated refuse-derived fuel (RDF) with a high (3 wt%) content in chlorine. In the gas cleaning reactor two main reactions occurred simultaneously: the elimination of HCl and the elimination of tar by steam reforming. The elimination of HCl formed CaCl2 and MgCl2 with melting points below the high (above 800 degrees C) temperatures required for the simultaneous tar elimination reaction. So, the CaO-based particles progressively melted and the catalytic gas cleaning reactor became a compact, agglomerated or glued, cake. Therefore, the life and usefulness of the CaO-based solids used was very low. Nevertheless, and to further avoid these problems, some positive guidelines for future research are proposed here. PMID:18372172

  4. Variation of photoluminescence features in Pr3+ doped lithium-fluoro-borate glass by changing different modifier oxides (MgO, CaO, CdO and PbO)-Judd-Ofelt theory application

    International Nuclear Information System (INIS)

    Pr3+ (1.0 mol%) doped different modifier oxide based six lithium-fluoro-borate glasses with chemical composition of 49Li2B4O7-20BaF2-10NaF-20MO (where M= Mg, Ca, Cd and Pb), 49Li2B4O7-20BaF2-10NaF-10MgO-10CaO and 49Li2B4O7-20BaF2-10NaF-10CdO-10PbO were prepared by conventional melt quenching technique. Judd-Ofelt theory has been applied for evaluating the Judd-Ofelt intensity parameters for Pr3+ ion in these glass compositions and are in turn to used to predict radiative properties such as radiative transition probabilities (AT), branching ratios (β) and stimulated emission cross-section (σP). Stimulated emission cross-section (σp) of prominent emission transitions, 3P0→3H4 and 1D2→3H4 of Pr3+ ion in all lithium-fluoro-borate glasses were calculated. Among all the emission transitions, 3P0→3H4 posseses higher branching ratio and stimulated emission cross-section in Mg-Ca glass, which leads to the best laser excitation at 487 nm wavelength

  5. Attaching an alkali metal atom to an alkaline earth metal oxide (BeO, MgO, or CaO) yields a triatomic metal oxide with reduced ionization potential and redirected polarity.

    Science.gov (United States)

    Nowiak, Grzegorz; Skurski, Piotr; Anusiewicz, Iwona

    2016-04-01

    The existence of a series of neutral triatomic metal oxides MON and their corresponding cations MON (+) (M = Be, Mg, Ca; N = Li, Na, K) was postulated and verified theoretically using ab initio methods at the CCSD(T)/6-311+G(3df)//MP2/6-311+G(3df) level of theory. The calculations revealed that the vertical ionization potentials (IPs) of the MON radicals (calculated using the outer-valence Green's function technique (OVGF) with the 6-311+G(3df) basis set) were ca. 2-3 eV smaller than the IPs of the corresponding MO and NO systems or that of the isolated M atom. Population analysis of the neutral triatomic MON molecules and their corresponding MO counterparts indicated that the attachment of an alkali metal atom to any oxide MO (BeO, MgO, CaO) reverses its polarity, which manifests itself as the redirection of the dipole moment vector. PMID:26994021

  6. Quaternary equilibrium diagrams ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}). A powerful tool for the development of new materials by reaction sintering; Diagramas de equilibrio cuaternarios ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}- (CaO, MgO, TiO{sub 2}). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterizacion reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J. S.; Bartolome, J. F.; Pena, P.

    2011-07-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported. (Author) 42 refs.

  7. Kinetics and mechanism of stepwise reduction of pure and Fe/sub 2/O/sub 3/ doped with either CaO and/or MgO fired compacts

    International Nuclear Information System (INIS)

    Fired pure Fe/sub 2/O/sub 3 doped with 0.5-5.0% of either CaO or MgO compacts were isothermally reduced at 1173-1473 K in CO atmosphere. The O/sub 2/-weight loss resulted from the reduction of iron oxide(s) was continuously recorded as a function of time. Partially and completely reduced samples were characterized. At a given temperature, compacts were reduced either directly to iron or in a stepwise manner (Fe/sub 2/O/sub 3/-Fe/sub 3/O/sub 4/-Fe) or Fe/sub 2/O/sub 3/- Fe/sub 0.943/O/sub -/Fe. Also compacts were reduced subsequently from Fe/sub 2/O/sub 3/ to Fe/sub 3/O/sub 4/ the to Fe/sub 0.943/O and finally to Fe. The apparent activation energy values were calculated at both of early and later reduction stages. Also, the different heterogeneous gas-solid reaction formulations were tested against the experimental reduction results. The structure of partially and completely reduced samples were microscopically examined and correlated with the structure to elucidate the reduction mechanism. The results obtained indicated that the presence of fluxing oxide (s) promote the reduction of pure hematite at the early stages due to the increase in their original porosity. At intermediate and later reduction stages, the presence of doping oxide(s) showed different effects depending on fluxing oxide content, reduction extent and temperature. The reduction mechanism elucidated was greatly influenced by the structure of intermediate solid phases (magnetite and/or wustite) developed prior to metallic iron. (author)

  8. Variation of photoluminescence features in Pr{sup 3+} doped lithium-fluoro-borate glass by changing different modifier oxides (MgO, CaO, CdO and PbO)-Judd-Ofelt theory application

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishna, A.; Rajesh, D.; Babu, S.; Ratnakaram, Y. C., E-mail: ratnakaramsvu@gmail.com [Department of Physics, S.V. University, Tirupati-517502 (India)

    2015-06-24

    Pr{sup 3+} (1.0 mol%) doped different modifier oxide based six lithium-fluoro-borate glasses with chemical composition of 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-20MO (where M= Mg, Ca, Cd and Pb), 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10MgO-10CaO and 49Li{sub 2}B{sub 4}O{sub 7}-20BaF{sub 2}-10NaF-10CdO-10PbO were prepared by conventional melt quenching technique. Judd-Ofelt theory has been applied for evaluating the Judd-Ofelt intensity parameters for Pr{sup 3+} ion in these glass compositions and are in turn to used to predict radiative properties such as radiative transition probabilities (A{sub T}), branching ratios (β) and stimulated emission cross-section (σ{sub P}). Stimulated emission cross-section (σ{sub p}) of prominent emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} and {sup 1}D{sub 2}→{sup 3}H{sub 4} of Pr{sup 3+} ion in all lithium-fluoro-borate glasses were calculated. Among all the emission transitions, {sup 3}P{sub 0}→{sup 3}H{sub 4} posseses higher branching ratio and stimulated emission cross-section in Mg-Ca glass, which leads to the best laser excitation at 487 nm wavelength.

  9. Diagramas de equilibrio cuaternarios ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterización reactiva

    OpenAIRE

    Moya, J.S.; Bartolomé, J. F.; Peña, P.

    2011-01-01

    En este articulo se exponen, discuten y evalúan los trabajos que sobre materiales de Mullita-Circona obtenidos por sinterización reactiva dirigió e inspiro Salvador de Aza sobre la base de los diagramas de equilibrio de fase multicomponentes ZrO2-Al2O3-SiO2-(CaO, MgO, TiO2). Se analiza su impacto en distintas áreas de la ciencia y tecnología cerámicas tales como chamotas refractarias, industria del aluminio, etc. También se proponen posibles campos de aplicación futura como es el ...

  10. CAOS-CMOS camera.

    Science.gov (United States)

    Riza, Nabeel A; La Torre, Juan Pablo; Amin, M Junaid

    2016-06-13

    Proposed and experimentally demonstrated is the CAOS-CMOS camera design that combines the coded access optical sensor (CAOS) imager platform with the CMOS multi-pixel optical sensor. The unique CAOS-CMOS camera engages the classic CMOS sensor light staring mode with the time-frequency-space agile pixel CAOS imager mode within one programmable optical unit to realize a high dynamic range imager for extreme light contrast conditions. The experimentally demonstrated CAOS-CMOS camera is built using a digital micromirror device, a silicon point-photo-detector with a variable gain amplifier, and a silicon CMOS sensor with a maximum rated 51.3 dB dynamic range. White light imaging of three different brightness simultaneously viewed targets, that is not possible by the CMOS sensor, is achieved by the CAOS-CMOS camera demonstrating an 82.06 dB dynamic range. Applications for the camera include industrial machine vision, welding, laser analysis, automotive, night vision, surveillance and multispectral military systems. PMID:27410361

  11. Characterisation and Properties of Lithium Disilicate Glass Ceramics in the SiO2-Li2O-K2O-Al2O3 System for Dental Applications

    OpenAIRE

    Naruporn Monmaturapoj; Pornchanok Lawita; Witoon Thepsuwan

    2013-01-01

    This work proposes four different glass formulas derived from the SiO2-Li2O-K2O-Al2O3 system to investigate the effect of glass composition on their crystal formations and properties. Glass LD1 was SiO2-Li2O-K2O-Al2O3 system with the addition of P2O5 and CaF2 as nucleating agents. In Glass LD2, a slight amount of MgO was mixed in order to increase the viscosity of the melting glass. Finally, the important factor of Si : Li ratio was increased in Glasses LD3 and LD4 with compositions otherwise...

  12. K2O/SBA-15的制备及其催化性能研究%Preparation and catalytic performance of mesoporous sieve catalyst K2O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健

    2011-01-01

    When potassium which was loaded to mesoporous sieve SBA-15 was calcined, K2O/SBA-15 as the solid base catalyst was synthesized. The synthesis of N-butyl acrylate was the probe reaction. The active value of K2O/SBA-15 catalyst has been carried on the transesterification in the inter mittent reactor.The results showed K2O/SBA-15 catalyst had the best catalytic active when the loaded amount of K2O added to 2%%以介孔分子筛SBA-15为载体,负载KNO3后焙烧制得K2O/SBA-15固体碱催化剂,以合成丙烯酸正丁酯的酯交换反应为探针反应,在间歇式反应釜中对K2O/SBA-15催化剂进行催化活性评价.结果表明,当K2O负载量为2%,K2O/SBA-15催化剂对此酯交换反应的催化活性最高.

  13. The K2O-CaO-V2O5 system

    International Nuclear Information System (INIS)

    The phase composition of the K2O-CaO-V2O5 system in the subsolidus region is investigated. The proper phase equilibrium diagram is plotted. The formation in the system of two new compounds-binary pyrovanadate K2CaV v2O7 and binary orthovanadate K4Ca(VO4)2 has been found. The temperatures of peritectic melting of the salts are 680 and 1250 deg c, respectively. Some physico-chemical characteristics of binary potassium- and calcium vanadates are determined

  14. Caos, fluidos y flujos

    OpenAIRE

    Luis Fernando Herrera Díaz; Alfonso Conde

    2011-01-01

    Desde hace aproximadamente 30 años, el mundo de la ciencia se revolucionó debido al nacimiento de un nuevo paradigma; a esta forma de ver el mundo se le conoce con el nombre de Teoría del Caos. En su corta vida, ya ''ha tocado todas las ramas del conocimiento, incluyendo por supuesto la Ingeniería" dice Mora (1998). Es así como muchos de los reconocidos ingenieros, como Aris en el campo de los reactores químicos, Froment en catálisis heterogénea, Coppens, que investiga los fenómenos de difusi...

  15. 介孔分子筛K2O/SBA-15催化酯化反应的研究%Esterification Catalyzed by Mesoporous Sieve K2 O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健; 刘琤; 沈思维

    2011-01-01

    以介孔分子筛SBA-15为载体,负载KNO3后经过煅烧,制得K2O/SBA-15固体碱催化剂.通过XRD和BET对样品进行了测试分析,并对K2O/SBA-15催化合成油酸甲酯的酯化反应进行了研究.试验结果表明:当K2O负载量为2%,n(醇)∶n(酸)2∶1,反应温度180℃,反应时间4 h,催化剂用量为原料质量的5.0%时,酯化率最大达到83.61%,并且K2O/SBA-15催化剂重复使用多次仍具有较好的催化效果.%Solid base catalyst K2O/SBA-15 was prepared by loading potassium nitrate on mesoporous sieve SBA-15 and then was calcined. The samples were characterized by XRD and BET and used as catalyst in the synthesis of methyl oleate. The experimental results showed that when the loaded amount of K2O was 2% , molar ratio of methanol/oleic acid was 2:1 ,reaction temperature was 180 ℃ ,reaction time was 4 h and the ratio of catalyst to raw material was 5% ( weight ratio), the esterification rate was 83.61%. The results also showed that K2O/SBA-15had a good catalytic effect after resued.

  16. Efeitos da fertirrigação de N e K2O na absorção de macronutrientes pela gravioleira Effects of fertirrigation of N and K2O on absorption of macronutrients by soursop crop

    Directory of Open Access Journals (Sweden)

    Roberto S. F. de H. Filho

    2006-03-01

    Full Text Available O objetivo deste trabalho foi avaliar o efeito de dosagens de N e K2O via água de irrigação na absorção de macronutrientes pela cultura da gravioleira. O experimento foi realizado no campo experimental da Embrapa Meio-Norte, situado no município de Teresina, PI (05º 05' S, 42º 48' W e 74,4 m de altitude. O delineamento experimental utilizado foi por blocos casualizados, com onze tratamentos e quatro repetições, com parcela útil composta de quatro plantas. Os tratamentos consistiram na aplicação de cinco dosagens de N (20, 120, 200, 280 e 380 kg ha-1 ano-1 combinadas com cinco dosagens de K2O (30, 180, 300, 420 e 570 kg ha-1 ano-1 de acordo com o modelo da matriz experimental Plan Plueba III, além de um tratamento com dosagem zero de ambos os nutrientes. Em nenhum dos tratamentos foi encontrado deficiência de N, K, Mg, S e P nas folhas da gravioleira. As dosagens de N, bem como as suas interações com as dosagens de K2O, não proporcionaram efeito significativo sobre os teores dos macronutrientes nas folhas da gravioleira. As dosagens de K2O influenciaram os teores dos macronutrientes Ca, K e Mg nas folhas da gravioleira.The objetive of this work was to evaluate the effect of doses of N and K2O through irrigation water on the absorption of macronutrients by soursop cultivation. The study was conducted at the experimental field of Embrapa - North, in Teresina, in the State of Piauí, Brazil (5º 05' S, 42º and 48' W. The experimental design was completely randomized blocks with eleven treatments and four repetitions. The treatments consisted in the application of five doses of N (20, 120, 200, 280 and 380 kg ha-1 year-1 combined with five doses of K2O (30, 180, 300, 420 and 570 kg ha-1 year-1 in agreement with the model of experimental matrix Plan Plueba III, besides a treatment with dose zero of both nutrients. No deficiency of N, K, Mg, S, and P in the soursop leaves was found in any treatment. The doses of N did not provide

  17. Effects of M2+ (M = Ca, Sr, and Ba Addition on Crystallization and Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass

    Directory of Open Access Journals (Sweden)

    Mrinmoy Garai

    2015-01-01

    Full Text Available In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3 is found to be decreased in presence of CaO and SrO. Tg is increased by 5–10°C and Td decreased by 13–20°C on addition of M2+. The variation of Tg, Td and decrease of thermal expansion (CTE from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h; and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2 by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material.

  18. Efeitos da fertirrigação de N e K2O na absorção de macronutrientes pela gravioleira Effects of fertirrigation of N and K2O on absorption of macronutrients by soursop crop

    OpenAIRE

    Roberto S. F. de H. Filho; Valdemício F. de Sousa; Benito M de Azevedo; Rosa M. C. M. de Alcantara; Valdenir Q. Ribeiro; Waleska M. Eloi

    2006-01-01

    O objetivo deste trabalho foi avaliar o efeito de dosagens de N e K2O via água de irrigação na absorção de macronutrientes pela cultura da gravioleira. O experimento foi realizado no campo experimental da Embrapa Meio-Norte, situado no município de Teresina, PI (05º 05' S, 42º 48' W e 74,4 m de altitude). O delineamento experimental utilizado foi por blocos casualizados, com onze tratamentos e quatro repetições, com parcela útil composta de quatro plantas. Os tratamentos consistiram na aplica...

  19. The Structural Optimization System CAOS

    DEFF Research Database (Denmark)

    Rasmussen, John

    1990-01-01

    CAOS is a system for structural shape optimization. It is closely integrated in a Computer Aided Design environment and controlled entirely from the CAD-system AutoCAD. The mathematical foundation of the system is briefly presented and a description of the CAD-integration strategy is given together...

  20. Partial hydrogenation of adiponitrile to 6-aminocapronitrile over Ni/α-Al2O3 catalyst promoted with K2O and La2O3

    Institute of Scientific and Technical Information of China (English)

    Lei Zhao; Cai Yun Wang; Ji Xiang Chen; Ji Yan Zhang

    2007-01-01

    A novel K2O and La2O3 promoted nickel catalyst supported on α-Al2O3 was prepared by co-impregnation method, and it exhibited higher activity and 6-aminocapronitrile selectivity than Ni/α-Al2O3 during the hydrogenation of adiponitrile in the absence of ammonia, i.e., K2O and La2O3 improved the performance of the nickel-based catalyst.

  1. Phase-formation in K2O-Er2O3-P2O5-H2O system

    International Nuclear Information System (INIS)

    The K2O-Er2O3-P2O5-H2O system in the condensed phosphates crystallization at 300 and 500 deg C and constant pressUre of saturated water vapours by the method is investigated. Crystallization tregions of eight condensed erbium phosphates haVe been found out: two varieties of ErP5O14 ultraphosphates, two Er(PO3)3 polyphospates (Q and R phases), KErP4O12-A double cyclotetraphosphate and three double KEr)/PO3)4 of 3, 4 and 7 types, polyphosphates the KEr(PO3)4 - 7 and Er(PO3)3 - R types are obtained for the first time. Roentgenometric, morphological, crystalloptical and IR spectroscopic characteristics of condensed erbium phosphates are given

  2. Synthesis and structure of nanomaterials in the system K2O-Nb2O5-SiO2

    Directory of Open Access Journals (Sweden)

    Georgi Chernev

    2009-06-01

    Full Text Available The aim of the present work is synthesis of ferroelectric nanomaterials, in the K2O-Nb2O5-SiO2 system via solgel method and studying the processes of formation and structure of the synthesized ferroelectric nanomaterials. The structure of synthesized materials has been studied by means of the following methods: EDS, XRD, FT-IR, SEM and AFM. The results obtained showed that the structure of the investigated compositions does not depend on the niobium content and all the samples keep their amorphous nature at room temperature. The surface structure shows random distribution of different kinds of aggregates with dimensions about 200–500 nm. The presence of a hybrid nanostructure with well-defi ned nanounits having special geometry is clearly observed.

  3. Diffuse Reflectance Infrared Fourier Transform Study of NOx Adsorption on CGO10 Impregnated with K2O or BaO

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund; Härelind Ingelsten, H.; Kammer Hansen, Kent

    2012-01-01

    , the effect on the NOx adsorption when adding K2O or BaO to the CGO is investigated. The DRIFT study shows mainly the presence of nitrate species at 500 °C, while at lower temperature a diversity of adsorbed NOx species exists on the CGO. Presence of O2 is shown to have a strong effect on the...... adsorption of NO, but no effect on the adsorption of NO2. Addition of K2O and BaO dramatically affects the NOx adsorption and the results also show that the adsorbed NOx species are mobile and capable of changing adsorption state in the investigated temperature range....

  4. Relationship between Leucite Content and Compressive Strength of K2O-Al2O3-SiO2 System Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; QIAN Fatang; DUAN Xinglong; WU Bolin

    2009-01-01

    Relationship between leucite content and compressive strength of K2O-Al2O3-SiO2 sys-tem dental glass ceramics were investigated. 10 groups of feedstock powder with different composi-tions were treated according to the same thermal treatment system of leucite micro-crystallization reported in some primary studies. The products of each group were analyzed by X-ray diffractometer,polaring microscope and scanning electronic microscope (SEM), and then the compressive strength was tested by a material testing machine. A direct proportion was found between leucite content and the compressive strength when leucite content was less than 50 vol%, and compressive strength de-creased with the increasing of leucite micro-crystals when leucite content was more than 50vol%, The leucite content has a notable influence on the compressive strength of K2O-Al2O3-SiO2 system dental glass ceramics.

  5. An attempt to reconstruct geodynamically the Belgian palaeogene basin from mineralogical clay data, from radioelement (U, Th, K2O) geochemistry and palynology

    International Nuclear Information System (INIS)

    By analysing clay mineralogy, U-Th-K2O geochemistry and palynology data, we find that the Belgian Palaeogene is dominated by the action of a biostasic period toward the end of the lower Eocene. At the middle Eocene starts a new phase, at least a rhexistasic one at the begining. In the Basin, the geochemical and mineralogical traces of this phase just start from the upper Eocene

  6. Reusability and Stability Tests of Calcium Oxide Based Catalyst (K2O/CaO-ZnO for Transesterification of Soybean Oil to Biodiesel

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2016-03-01

    Full Text Available This paper was purposed for testing reusability and stability of calcium oxide-based catalyst (K2O/CaO-ZnO over transesterification reaction of soybean oil with methanol to produce biodiesel. The K2O/CaO-ZnO catalyst was synthesized by co-precipitation method of calcium and zinc nitrates followed by impregnation of potassium nitrate. The fresh and used catalysts were tested after regeneration. The catalysts were characterized by Scanning Electron Microscopy (SEM, X-ray Diffraction (XRD, and BET Surface Area in order to compare the catalyst structure between the fresh and used catalysts. The catalyst testing in transesterification proses was carried out at following operating conditions, i.e. catalyst weight of 6 wt.%, oil to methanol mole ratio of 1:15, and temperature of 60 oC. In addition, metal oxide leaching of K2O/CaO-ZnO catalyst during reaction was also tested. From the results, the catalysts exhibited high catalytic activity (80% fatty acid methyl ester (FAME yield after three-cycles of usage and acceptable reusability after regeneration. The catalyst also showed acceptable stability of catalytic activity, even after three-cycles of usage. Copyright © 2016 BCREC GROUP. All rights reserved Received: 10th November 2015; Revised: 16th January 2016; Accepted: 16th January 2016 How to Cite: Istadi, I., Mabruro, U., Kalimantini, B.A.,  Buchori, L., Anggoro, D.D. (2016. Reusability and Stability Tests of Calcium Oxide Based Catalyst (K2O/CaO-ZnO for Transesterification of Soybean Oil to Biodiesel. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 34-39. (doi:10.9767/bcrec.11.1.413.34-39 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.413.34-39

  7. Physico-chemical properties of molten K2O-V2O5 catalyst in the reaction-regeneration cycle

    International Nuclear Information System (INIS)

    The interaction of molten catalyst (MC) of the K2O-V2O5 composition with a reducing mixture of gases (hydrocarbons) results in the formation of V2O4, the solubility of which in MC is limited. The V2O4 obtained decreases the surface tension and increases the MC density. Air purging practically leads the MC to the initial state. The V2O4 forms a new phase at the interface, creating a resistance of physical character for diffusing gas particles on the one hand, and a deficit of reactive oxygen, on the other hand

  8. Carbonate capacities of CaF2-MgO and CaF2-CaO-MgO slags

    International Nuclear Information System (INIS)

    The refining abilities of slags for impurities in steel, such as sulfur and phosphorus, can be related to slag basicity and it has been found that carbonate capacity can be employed as a basicity index. In the present study, the carbonate capacities of the binary CaF2-Mgo system and the ternary CaF2-CaO-MgO system were measured in the temperature range of 1360-1480 oC. The carbonate capacity in the CaF2-MgO system increased with increasing MgO concentration. Replacement of CaF2 by CaO at constant MgO and replacement of MgO by CaO at constant CaF2 in the CaF2-CaO-MgO system resulted in an increase in the carbonate capacity. The amount of dissolved CO2 in both the CaF2-MgO and the CaF2-CaO-MgO systems increased with increasing partial pressure of CO2. There was a linear relationship between the partial pressure of CO2 and the mole fractions of both MgO and CaO. In addition, the carbonate capacities of both the binary and the ternary systems decreased with increasing temperature. This demonstrates that the dissolution of CO2 is exothermic. The enthalpy of dissolution of CO2 for the CaF2-MgO binary system was within the range of -116 to -49.61 kJ/mole and for the CaF2-CaO-MgO ternary system it was within the range of -247.30 to -136.23 kJ/mole. Using the thermodynamic data available in the literature, the sulfide capacities were calculated for the CaF2-MgO system. The concept of optical basicity was employed to discuss the results. (author)

  9. Structural investigation of V$_2$O$_5$–P$_2$O$_5$–K$_2$O glass system with antibacterial potential

    Indian Academy of Sciences (India)

    N S VEDEANU; I B COZAR; R STANESCU; R STEFAN; D VODNAR; O COZAR

    2016-06-01

    The $x$V$_2$O($1 − x$)[0.8 P$_2$O$_5$·0.2K$_2$O] glass system with $0 \\lt x \\lt 50$ mol% was prepared and the structural changes induced in these glasses by increasing the vanadium oxide content were investigated by IR and ESR spectroscopies. The dual behaviour role of V$_2$O$_5$ oxide, as network modifier (for $x\\lt 10$ mol%) and the network former ($x\\gt 20$ mol%), as a consequence of phosphate network depolymerization and P–O–V and V–O–V linkages appearance was also highlighted. The antibacterial effect of the glasses with $x \\lt 20$ mol% V$_2$O$_5$ content was tested by optical density (OD) measurements. A linear correlation between the amount of vanadium and the antibacterial effect was evidenced.

  10. Experimental Work Conducted on MgO Inundated Hydration in WIPP-Relevant Brines

    Science.gov (United States)

    Deng, H.; Xiong, Y.; Nemer, M. B.; Johnsen, S.

    2009-12-01

    Magnesium oxide (MgO) is being emplaced in the Waste Isolation Pilot Plant (WIPP) as an engineered barrier to mitigate the effect of microbial CO2 generation on actinide mobility in a postclosure repository environment. MgO will sequester CO2 and consume water in brine or water vapor in the gaseous phase. Martin Marietta (MM) MgO is currently being emplaced in the WIPP. A fractional-factorial experiment has been performed to study the inundated-hydration of MM MgO as a function of its particle size, solid-to-liquid ratio, and brine type. MgO hydration experiments have been carried out with three MgO particle sizes and two solid-to-liquid ratios in three WIPP-related brines: ERDA-6, GWB and simplified GWB. ERDA-6 is a synthetic NaCl-rich brine typical of a Castile brine reservoir below the repository. GWB is a synthetic MgCl2- and NaCl-rich brine representative of intergranular brines from the Salado Formation at or near the stratigraphic horizon of the repository. Simplified GWB contains amounts of Mg, Na, and Cl similar to those in GWB without other minor constituents. The hydration products include brucite (Mg(OH)2) and phase 5 (Mg3(OH)5Cl4H2O). In addition to phase 5, MgO hydration in GWB or simplified GWB produces brucite, whereas MgO hydrated in ERDA-6 only produces brucite. The MgO particle size has had a significant effect on the formation of hydration products: small MgO particles have hydrated before the large particles. MgO has hydrated faster in simplified GWB than in the other two brines. In ERDA-6, the solid-to-liquid ratio has affected the brine pH due to the presence of CaO (~1 wt %) as an impurity in MM MgO. GWB has sufficient dissolved Mg to buffer pH despite small amounts of CaO. Both our results and thermodynamic modeling indicate that phase-5 is the stable Mg-OH-Cl phase in Mg-Na-Cl-dominated brines with ionic strengths and chemical compositions similar to that of GWB. In contrast, phase-3 (Mg2(OH)3Cl4H2O) is the stable phase in the MgCl2

  11. 27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy of glasses in the system K2O-Al2O3-SiO2.

    Science.gov (United States)

    Mundus, C; Müller-Warmuth, W

    1995-10-01

    27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy at 78 MHz has been applied to determine (true) chemical shift and quadrupole coupling parameters of glasses in the system K2O-Al2O3-SiO2 with 60-80 mol% SiO2 and K2O concentrations between 0 and 24 mol%. The powdered crystalline aluminosilicates andalusite and sillimanite have also been examined. In the glasses, all Al appears to be tetrahedrally bound in the aluminosilicate network unless x = mol% K2O:mol% Al2O3 becomes extremely small. Upon decreasing x the distortion of the tetrahedral Al(OSi)4 units increases in steps, and possible explanations are discussed. Six-coordinated aluminum observed for x < 0.2 is connected with the occurrence of interstitial Al3+ ions which charge-compensate the AlO4 units in addition to K+. PMID:8748646

  12. Influences of Heat Treatments on Crystallization in SiO2-Al2O3-MgO-K2O-F Glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    TIAN Qingbo; XU Lina; YANG Li; WANG Xiuhui; GAO Hong

    2011-01-01

    Five kinds of heating treatment processing were chosen according to the experiment result of differential scanning calorimeter to prepare SiO2-Al2O3-MgO-K2O-F glass ceramics samples. The effects of heat treatment processing on the crystallization of these samples were explored by X-ray diffraction and scanning electron microscopy techniques. The results indicate that phase separations can occur in the bulk regions of the glass sample when holding at 670 ℃ for 3 h. The phase separation can accelerate the precipitation of the crystallization phase: when the temperature directly rises to 950 ℃ after the phase separation, there are mainly interlocked plate-shapes mica phases; If holding at 860 ℃ for 3 h first after the phase separation, the star-shape cordierite phases form; Thereby, elevating temperature to 950 ℃ and holding for l h will bring plate-shapes mica phases growing at inter-phases of the star-shape cordierite and finally the homogeneously distributed micacordierite composites form. However, if heating at 950 ℃ directly without holding at 670 ℃, there is a small quantity of phase separation appearing at 670 ℃ and a little crystallization phases precipitating at last.

  13. Assimilation Behavior of Calcium Ferrite and Calcium Diferrite with Sintered Al2O3 and MgO

    Science.gov (United States)

    Long, Hongming; Wu, Xuejian; Chun, Tiejun; Di, Zhanxia; Yu, Bin

    2016-06-01

    In this study, the assimilation behaviors between calcium ferrite (CF), calcium diferrite (CF2) and sintered Al2O3, and MgO were explored by an improved sessile drop technique, and the interfacial microstructure was discussed. The results indicated that the apparent contact angles of CF slag on Al2O3 and MgO substrate were 15.7 and 5.5 deg, and the apparent contact angles of CF2 slag on Al2O3 and MgO substrate were 17.9 and 7.2 deg, respectively. Namely, CF and CF2 slag were wetting well with Al2O3 and MgO substrate. The dissolution of Al2O3 substrate into the CF and CF2 slag was found to be the driving force of the wetting process. For the CF-MgO and CF2-MgO substrate systems, CaO contrarily distributed with MgO after wetting. For the CF-MgO system, after wetting, the slag was composed of CF and C2F, and most of the Fe2O3 permeated into substrate and formed two permeating layers.

  14. Effect of MgO and MnO on Phosphorus Utilization in P-Bearing Steelmaking Slag

    Science.gov (United States)

    Lin, Lu; Bao, Yan-Ping; Wang, Min; Li, Xiang

    2016-04-01

    In order to recycle the phosphorus in P-bearing converter slag and make it used as slag phosphate fertilizer, the effect of MgO and MnO in P-bearing steelmaking slag on phosphorus existence form, P2O5 solubility and magnetic separation behavior were researched systematically. The results show that the phosphorus in slag is mainly in the form of n2CaO · SiO2-3CaO · P2O5 (for short nC2S-C3P) solid solution in the P-rich phase for CaO-SiO2-FetO-P2O5-X (X stands for MgO and MnO, respectively). And the increasing of MgO and MnO content has no influence on precipitation of nC2S-C3P solid solution in slag, MnO and MgO mainly enter into RO phase and base phase to form MnFe2O4 and MgFe2O4, which has little effect on the P2O5 content of P-rich phase, so which has little effect on the degree of phosphorus enrichment and phosphorus occurrence form of the P-bearing slag. And adding MgO and MnO into CaO-SiO2-P2O5-Fe2O3 slag system can break the complex net structure formed by Si-O on certain degree, and also hinder the precipitation of β-Ca3(PO4)2 crystal with low citric acid solubility during the melting-cooling process. Therefore, adding appropriate MgO and MnO content into slag can improve the slag P2O5 solubility, but the effect of different amounts of MgO and MnO on the P2O5 solubility has little difference. Meanwhile, adding MgO and MnO into slag can improve the metallization of slag and magnetism of iron-rich phase, make the magnetic substances content increase and separation of phosphorus and iron incomplete, so it is adverse to phosphorus resources recovery from P-bearing slag by magnetic separation method. In order to recycle the phosphorus in P-bearing converter slag, the MgO and MnO content in the P-bearing slag should be controlled in the steelmaking process.

  15. 氧化钾/SBA-15催化合成碳酸二正丁酯%SYNTHESIS OF DIBUTYL CARBONATE BY TRANSESTERIFICATION OVER MESOPOROUS MOLECULAR SIEVE K2O/SBA-15

    Institute of Scientific and Technical Information of China (English)

    崔晓燕; 沈健

    2011-01-01

    以介孔分子筛SBA-15为载体,浸渍KNO3后经过焙烧,制得K2O/SBA-15固体碱催化剂.通过XRD,N2等温吸附脱附和IR等测试手段对试样进行了分析.研究了K2O/SBA-15催化碳酸二甲酯(DMC)与正丁醇(n-BuOH)酯交换合成碳酸二正丁酯(DBC)的反应.结果表明:当K2O负载量为2%,反应时间2 h,反应温度180℃,n(正丁醇)∶n(DMC)为3.0,m(催化剂)∶m(原料)为0.08时,DMC转化率最大为89.6%,DBC 收率为58%,DBC选择性为64.7%.并且K2O/SBA-15催化剂重复使用多次仍具有较好的催化效果.%K2O/SBA-15 as the solid base catalyst was synthesized bu loading potassium on mesoporous sieve SBA-15.The sample has been characterized by XRD, N2 adsorption desorption and IR.The study on the synthesis of dibutyl carbonate from dimethyl carbonate and butanol has been done.The experimental results showed that when the loaded mount of K2 O was 2 %, reaction time was 2 h, reaction temperature was 180 ℃ ,n(n-butanol): n(dimethyl carbonate) was 3 and the ratio of catalyst to raw material was 8%, the highest conversion of dimethyl carbonate was 89.6%, the yield of DBC was 58%, the selectivity to DBC was 64.7%.The results also showed that the K2O/SBA-15 could be reused with good catalytic effect.

  16. Security of the Cao-Li Public Key Cryptosystem

    OpenAIRE

    Lim, Lek-Heng

    2000-01-01

    We show that the Cao-Li cryptosystem proposed in \\cite{CL1} is not secure. Its private key can be reconstructed from its public key using elementary means such as LU-decomposition and Euclidean algorithm.

  17. Untersuchung des Einflusses von Sulfaten auf das System CaO-SiO2-Al2O3-K2O-H2O mittels Wärmeflusskalorimetrie und in-situ Neutronenbeugung unter hydrothermalen Bedingungen

    OpenAIRE

    Walk-Lauffer, Bernd

    2005-01-01

    Untersuchung des Einflusses von Sulfaten auf das System CaO-SiO2-Al2O3-K2O-H2O mittels Wärmeflusskalorimetrie und in-situ Neutronenbeugung unter hydrothermalen Bedingungen Porenbeton besteht aus den Rohstoffen Sand, Zement, Branntkalk, Wasser und Aluminiumpulver (zur Porosierung). Zusätzlich werden Sulfatträger zur Verbesserung der physiko-mechanischen Eigenschaften Druckfestigkeit und Schwindung eingesetzt. Ziel dieser Arbeit war es, die Wirkung von Sulfat bzw. verschiedener Sul...

  18. Antibacterial characteristics of CaCO3-MgO composites

    International Nuclear Information System (INIS)

    Dentifrices, such as tooth-paste, are pastes containing insoluble abrasives that aid in the removal of plaque from the teeth and help to polish them. Composite powders contributing to oral hygiene application, i.e., nano-scale MgO crystallite dispersed in CaCO3 grain, were fabricated by the thermal decomposition of dolomite. The composite obtained by heating at 800 deg. C consisted of CaCO3 grains including 20 nm MgO fine crystallite, being the purpose powder in this study. The antibacterial activity of these powders related to gram-positive and gram-negative bacteria was evaluated in vitro. The thermal decomposition above 800 deg. C resulted in the mixture of CaO and MgO. Antibacterial activity of the composite enhanced with increasing powder concentration. Though antibacterial action toward Staphylococcus aureus was greater than towards Escherichia coli, the death rate constant was identical in both bacteria. It can be concluded that the obtained composite possesses two functions able to improve the oral hygiene: as a tooth abrasive and as an antibacterial agent.

  19. Antibacterial characteristics of CaCO{sub 3}-MgO composites

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Osamu, E-mail: yamamoto@cges.akita-u.ac.jp [Center for Geo-Environmental Science, Faculty of Engineering and Resource Science, Akita University, 1-1 Tegata Gakuen-machi, Akita 010-8502 (Japan); Ohira, Toshiaki; Alvarez, Kelly [Center for Geo-Environmental Science, Faculty of Engineering and Resource Science, Akita University, 1-1 Tegata Gakuen-machi, Akita 010-8502 (Japan); Fukuda, Masayuki [Division of Dentistry and Oral Surgery, Akita University Hospital, 1-1-1 Hondo, Akita 010-8543 (Japan)

    2010-10-15

    Dentifrices, such as tooth-paste, are pastes containing insoluble abrasives that aid in the removal of plaque from the teeth and help to polish them. Composite powders contributing to oral hygiene application, i.e., nano-scale MgO crystallite dispersed in CaCO{sub 3} grain, were fabricated by the thermal decomposition of dolomite. The composite obtained by heating at 800 deg. C consisted of CaCO{sub 3} grains including 20 nm MgO fine crystallite, being the purpose powder in this study. The antibacterial activity of these powders related to gram-positive and gram-negative bacteria was evaluated in vitro. The thermal decomposition above 800 deg. C resulted in the mixture of CaO and MgO. Antibacterial activity of the composite enhanced with increasing powder concentration. Though antibacterial action toward Staphylococcus aureus was greater than towards Escherichia coli, the death rate constant was identical in both bacteria. It can be concluded that the obtained composite possesses two functions able to improve the oral hygiene: as a tooth abrasive and as an antibacterial agent.

  20. Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol Over Nano-Catalysts Supported on CeO2-MgO.

    Science.gov (United States)

    Jun, Jin Oh; Lee, Joongwon; Kang, Ki Hyuk; Song, In Kyu

    2015-10-01

    A series of CeO2(X)-MgO(1-X) (X = 0, 0.25, 0.5, 0.75, and 1.0) nano-catalysts were prepared by a co-precipitation method for use in the synthesis of dimethyl carbonate from ethylene carbonate and methanol. Among the CeO2(X)-MgO(1-X) catalysts, CeO2(0.25)-MgO(0.75) nano-catalyst showed the best catalytic performance. Alkali and alkaline earth metal oxides (MO = Li2O, K2O, Cs2O, SrO, and BaO) were then supported on CeO2(0.25)-MgO(0.75) by an incipient wetness impregnation method with an aim of improving the catalytic performance of CeO2(0.25)-MgO(0.75). Basicity of the catalysts was determined by CO2-TPD experiments in order to elucidate the effect of basicity on the catalytic performance. The correlation between catalytic performance and basicity showed that basicity played an important role in the reaction. Yield for dimethyl carbonate increased with increasing basicity of the catalysts. Among the catalysts tested, Li2O/CeO2(0.25)-MgO(0.75) nano-catalyst with the largest basicity showed the best catalytic performance in the synthesis of dimethyl carbonate. PMID:26726512

  1. Synthesis and sintering of nanocrystalline thoria doped with CaO and MgO derived through oxalate-deagglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Ananthasivan, K., E-mail: asivan@igcar.gov.in [Chemistry Group, IGCAR, Kalpakkam 603 102 (India); Balakrishnan, S.; Anthonysamy, S. [Chemistry Group, IGCAR, Kalpakkam 603 102 (India); Divakar, R.; Mohandas, E. [Physical Metallurgy Division, Metallurgy Group, IGCAR, Kalpakkam 603 102 (India); Ganesan, V. [Chemistry Group, IGCAR, Kalpakkam 603 102 (India)

    2013-03-15

    Thorium dioxide doped with oxides of magnesium and calcium was prepared from deagglomerated mixed oxalates. The influence of the dopant oxide concentration (0.1, 0.25 and 0.5 mol% MO, M = Mg, Ca) on the powder properties was studied. The dependence of bulk density, specific surface area, X-ray crystallite size, residual carbon content and distribution of particle size on the dopant concentrations was investigated in detail. The transmission electron microscopy (TEM) investigations revealed that the powders comprised cuboidal agglomerates with a nanocrystalline substructure (10 nm). It was found that 0.5 mol% calcia doped thoria exhibits better sinterability than pure thoria and magnesia doped thoria at a temperature as low as 1673 K. Further, it was demonstrated for the first time that doping nanocrystalline thoria with calcia helps reduce the de-sintering phenomena.

  2. Biodiesel Production From the Microalgae Nannochloropsis by Microwave Using CaO and MgO Catalysts

    OpenAIRE

    Herman Hindarso; Aylianawati Aylianawati; Martinus Edy Sianto

    2015-01-01

    The needs of world petroleum are increased; in contrast, the fuel productions are getting decreased. Therefore, it has lead to the search for bio-fuel as an alternative energy. There are several different types of biofuel, such as biodiesel, ethanol, bioalcohol, and biogas. Biodiesel is typically made by chemically reacting lipids from a vegetable oil or animal fat with an alcohol producing fatty acid esters, such as methyl or ethyl ester. The present study aimed to study the effect of temper...

  3. Effects of sodium and potassium ions on a novel SeO2-B2O3-SiO2-P2O5-CaO bioactive system

    Science.gov (United States)

    Trandafir, D. L.; Ponta, O.; Ciceo-Lucacel, R.; Simon, V.

    2015-01-01

    The study is focused on Na2O and/or K2O influence on a new sol-gel derived SeO2-B2O3-SiO2-P2O5-CaO bioactive system. The structural changes induced by Na2O and/or K2O addition were correlated with the samples behavior in simulated biological media. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the structure and the type of the chemical bonds. The morphology of the samples was characterized through scanning electron microscopy (SEM). XRD results pointed out a prevalent vitreous structure with an incipient hydroxyapatite (HA) crystalline phase. FTIR results revealed a complex network consisting of silicate, phosphate and borate units, as well as the development of both A- and B-type of carbonate-substituted HA. The bioactivity of the samples was tested in vitro following the evolution of the apatite layers self-assembled on the samples surface in simulated body fluid. Their biocompatibility was investigated after samples surface functionalization with protein. The results indicate that sodium and potassium addition improves the biocompatibility by enhancement of protein adherence on samples surface and without to prevent the samples bioactivity.

  4. Active sites for methane activation in MgO and Li doped MgO

    OpenAIRE

    Kwapień, Karolina

    2012-01-01

    Die vorliegende Dissertation präsentiert eine detaillierte quantenchemische Untersuchung der H-Abstraktion von Methan durch MgO und Li dotiertes MgO. Motiviert wurde die durch das UniCat-Excellenz-Cluster, welches sich zum Ziel gesetzt hat, die oxidative Kupplung von Methan (OCM) im Detail zu verstehen. Basierend auf der Hypothese, dass Li+O•– Spezies für den H-Abstraktion Schritt verantwortlich sind, wurden kleine kationische MgO- und Li dotierte MgO-Cluster (die O•– Sites modellieren) unt...

  5. Nanosize MgO as antibacterial agent: preparation and characteristics

    OpenAIRE

    Zhen-Xing Tang; Xiu-Juan Fang; Zhi-Liang Zhang; Ting Zhou; Xin-Yi Zhang; Lu-E Shi

    2012-01-01

    The antibacterial activity of MgO nanoparticles prepared by a sonication method was evaluated in this paper. The effect of calcination conditions on the size and antibacterial activity of MgO nanoparticles was investigated. MgO nanoparticles were characterized for purity (TGA), crystallinity and crystal size (XRD), particle size and morphology (TEM) and surface area (BET). Results showed that the smallest size of 6 nm could be obtained. The lethal effects of nanocrystalline MgO were evaluated...

  6. XPS study of CaO in sodium silicate glass

    International Nuclear Information System (INIS)

    This paper shows that CaO added to silicate glasses behaves much like Na2O in converting bridging oxygen sites to nonbridging sites. Good correspondence with model predictions was obtained but deviations were still sufficiently large to warrant attention. We speculate that some CaO may remain unreacted or that small-scale phase separation may occur. XPS core level shifts were monitored and possible charge-transfer effects were considered. Preliminary theoretical calculations utilizing a molecular-cluster approach were presented. XPS spectra for various glass compositions were simulated by appropriately combining local densities of state calculated for individual atoms. Dominant spectral features observed experimentally were found in the simulations. In conjunction with experiments, more carefully refined calculations will be subsequently examined. 7 figures

  7. El lenguaje y la teoría del caos

    Directory of Open Access Journals (Sweden)

    Natalia Bondarenko Pisemskaya

    2007-01-01

    Full Text Available El presente estudio pretende establecer un puente conceptual entre la teoría del caos y la lingüística, campo renuente para incorporar este nuevo paradigma. Se explica que esto se debe principalmente a la influyente obra de F. de Saussure, impregnada por la doctrina lingüística positivista. Sin embargo, a partir de ejemplos concretos se demuestra que una perspectiva interdisciplinar permite apreciar manifestaciones de las leyes del caos en el lenguaje. Se concluye que a pesar de las diferencias es posible visualizar el lenguaje como sistema caótico y así relacionar estas dos áreas de conocimiento aparentemente incompatibles.

  8. Formation and Stability of Hollow MgO Nanoshells

    NARCIS (Netherlands)

    Krishnan, G.; Palasantzas, G.; Kooi, B.J.

    2010-01-01

    High temperature annealing of gas phase synthesized Mg nanoparticles surrounded by an MgO shell leads to formation of hollow MgO nanoshells due to the evaporation assisted Kirkendall effect. Under electron beam exposure in TEM, the (220) MgO facets reduce their high surface energy by forming cube fa

  9. Full-potential KKR-calculations for MgO and divalent impurities in MgO

    OpenAIRE

    Baranov, A. N.; Stepanyuk, V. S.; Hergert, W.; Katsnelson, A. A.; Settels, A.; Zeller, R.; Dederichs, P. H.

    2002-01-01

    We present a detailed investigation of bulk properties of MgO and lattice relaxations around divalent impurities in MgO by means of the full-potential Korringa-Kohn-Rostoker Green's function method. The local-density approximation and the perturbative generalized gradient corrections are used to calculate the lattice constant and bulk modulus of MgO. We obtain a very good description of the ground properties of MgO. Lattice relaxations around divalent impurities in MgO are determined using an...

  10. K2O对合成 DMC用 Cu-Ni/V2O5-SiO2催化剂性能的影响%Effect of K2O on Properties of Cu-Ni/V2O5-SiO2 Catalyst for the Synthesis of Dimethyl Carbonate

    Institute of Scientific and Technical Information of China (English)

    黎汉生; 钟顺和; 王建伟; 肖秀芬

    2001-01-01

    V2O5-SiO2(VSiO) supported Cu-Ni-K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro-reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu-Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15 % , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu-Ni-K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by-products decreases.

  11. The Oxygenase CAO-1 of Neurospora crassa Is a Resveratrol Cleavage Enzyme

    KAUST Repository

    Diaz-Sanchez, V.

    2013-07-26

    The genome of the ascomycete Neurospora crassa encodes CAO-1 and CAO-2, two members of the carotenoid cleavage oxygenase family that target double bonds in different substrates. Previous studies demonstrated the role of CAO-2 in cleaving the C40 carotene torulene, a key step in the synthesis of the C35 apocarotenoid pigment neurosporaxanthin. In this work, we investigated the activity of CAO-1, assuming that it may provide retinal, the chromophore of the NOP-1 rhodopsin, by cleaving β-carotene. For this purpose, we tested CAO-1 activity with carotenoid substrates that were, however, not converted. In contrast and consistent with its sequence similarity to family members that act on stilbenes, CAO-1 cleaved the interphenyl Cα-Cβ double bond of resveratrol and its derivative piceatannol. CAO-1 did not convert five other similar stilbenes, indicating a requirement for a minimal number of unmodified hydroxyl groups in the stilbene background. Confirming its biological function in converting stilbenes, adding resveratrol led to a pronounced increase in cao-1 mRNA levels, while light, a key regulator of carotenoid metabolism, did not alter them. Targeted Δcao-1 mutants were not impaired by the presence of resveratrol, a phytoalexin active against different fungi, which did not significantly affect the growth and development of wild-type Neurospora. However, under partial sorbose toxicity, the Δcao-1 colonies exhibited faster radial growth than control strains in the presence of resveratrol, suggesting a moderate toxic effect of resveratrol cleavage products.

  12. Conference “Computational Analysis and Optimization” (CAO 2011)

    CERN Document Server

    Tiihonen, Timo; Tuovinen, Tero; Numerical Methods for Differential Equations, Optimization, and Technological Problems : Dedicated to Professor P. Neittaanmäki on His 60th Birthday

    2013-01-01

    This book contains the results in numerical analysis and optimization presented at the ECCOMAS thematic conference “Computational Analysis and Optimization” (CAO 2011) held in Jyväskylä, Finland, June 9–11, 2011. Both the conference and this volume are dedicated to Professor Pekka Neittaanmäki on the occasion of his sixtieth birthday. It consists of five parts that are closely related to his scientific activities and interests: Numerical Methods for Nonlinear Problems; Reliable Methods for Computer Simulation; Analysis of Noised and Uncertain Data; Optimization Methods; Mathematical Models Generated by Modern Technological Problems. The book also includes a short biography of Professor Neittaanmäki.

  13. ENTENDRE EL CAOS. Retícules i vida quotidiana

    OpenAIRE

    Songel González, Gabriel

    2016-01-01

    La exposición se plantea como un recorrido visual por las diferentes manifestaciones de redes y retículas en algunos de los campos de observación existentes en la Naturaleza, en la aplicación como principio compositivo en las técnicas constructivas del pasado y en la tecnología actual. Songel González, G. (2016). ENTENDRE EL CAOS. Retícules i vida quotidiana. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/63822.

  14. Effect of CaO composition on oxidation and burning behaviors of AM50 Mg alloy

    Institute of Scientific and Technical Information of China (English)

    Jin-Kyu LEE; Shae K. KIM

    2011-01-01

    Oxidation and burning behaviors were studied for CaO added AM50 Mg composites which were manufactured by conventional melting and casting processes without SF6 protective gas. CaO added AM50 Mg composites show the stable oxidation resistance. while AM50 Mg alloys show the poor oxidation resistance. The effects of CaO addition on the burning resistance under ambient, nitrogen and dry air atmospheres were examined for CaO added AM50 Mg composites. With increasing CaO addition, the burning temperature increases under ambient, nitrogen and dry air atmospheres. The burning temperatures of small test specimen under all conditions greatly increase even by 0.3% CaO (mass fraction) addition into AM50 Mg alloys.

  15. Development of electrically insulating CaO coatings

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Reed, C.B.; Uz, M.; Rink, D.L. [Argonne National Lab., IL (United States)

    1998-09-01

    A systematic study has been initiated to develop electrically insulating CaO coatings by vapor phase transport and by in-situ formation in a liquid Li environment. Several experiments were conducted in vapor transport studies with variations in process temperature, time, specimen location, specimen surface preparation, and pretreatment. Several of the coatings obtained by the method exhibited Ca concentration in the range of 60--95 wt.% on the surface. However, coating thickness has not been very uniform among several samples exposed in the same run or even within the same sample. The coatings developed in these early tests degraded after 24 h exposure to Li at 500 C. Additional experiments are underway to develop better-adhering and more dense coatings by this method. A program to develop in-situ CaO coatings in Li has been initiated, and the first set of capsule tests at 800 C in three different Li-Ca mixtures will be completed in early July. Specimens included in the run are bare V-4Cr-4Ti alloy, specimens with a grit-blasted surface and O-precharged in 99.999% Ar, polished specimens precharged in a 99.999% Ar and 5000 ppm O{sub 2}-N{sub 2} mixture, and prealuminized V-5Cr-5Ti alloy preoxidized in a 5000 ppm O{sub 2}-N{sub 2} mixture. Additional experiments at lower temperatures are planned.

  16. СТЕКЛА СИСТЕМ K 2O-NB 2O 5-SIO 2 И K 2O-NB 2O 5-B 2O 3 С НИЗКИМ СОДЕРЖАНИЕМ СТЕКЛООБРАЗОВАТЕЛЯ

    OpenAIRE

    Рыженков, В.; Савельева, С.; Голубев, Н.; Лотарев, С.; Сигаев, В.

    2008-01-01

    Изучено стеклообразование и кристаллизация стекол в системах K 2O-Nb 2O 5-SiO 2 (KNS) и K 2O-Nb 2O 5-B 2O 3 (KNB) при содержаниях SiO 2 и B 2O 3 менее 50 мол.% в условиях повышенных скоростей охлаждения расплава. Прессованием получены рентгеноаморфные пластины при минимальном содержании SiO 2(B 2O 3) 12 мол.%. Раздувом расплава получены волокнистые и чешуйчатые аморфные материалы при концентрации стеклообразователя до 1 мол.%. KNB и высокосиликатные KNS стекла кристаллизуются с образованием п...

  17. Optical and fluorescence spectroscopy of Eu2O3-doped P2O5-K2O-KF-MO-Al2O3 (M = Mg, Sr and Ba) glasses

    Science.gov (United States)

    Kumar, K. Upendra; Babu, S. Surendra; Rao, Ch. Srinivasa; Jayasankar, C. K.

    2011-06-01

    Fluorophosphate glasses of composition, P2O5 + K2O + KF + MO + Al2O3 + xEu2O3 (M = Mg, Sr and Ba; x = 0.01, 0.05, 0.1, 1.0, 2.0, 4.0 and 6.0 mol%) were prepared and characterized their optical properties. Crystal-field (CF) analysis revealed a relatively weak CF strength around Eu3+ ions in the Ba based fluorophosphate glasses. The Judd-Ofelt parameters have been estimated from the oscillator strengths of 7F0 → 5D2, 7F0 → 5D4 and 7F0 → 5L6 absorption transitions of Eu3+ ions and were used to evaluate the radiative properties of the 5D0 → 7FJ (J = 0-4) transitions. Considerable variation has been observed in the relative intensity ratio of 5D0 → 7F2 to 5D0 → 7F1 transitions of Eu3+ ions due to change in the alkaline earth metal ions. The decay of the 5D0 level shows single exponential and less sensitive to Eu3+ ions concentration as well as MgO/SrO/BaO modifiers.

  18. MgO nanoparticles as antibacterial agent: preparation and activity

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhen-Xing, E-mail: tangzhenxing@126.com [Department of Food Science, Anqing, Vocational and Technical College, Anqing, Anhui (China); Lv, Bin-Feng [Date Palm Research Center, King Faisal University, (Saudi Arabia)

    2014-07-15

    Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are reviewed. (author)

  19. MgO nanoparticles as antibacterial agent: preparation and activity

    Directory of Open Access Journals (Sweden)

    Zhen-Xing Tang

    2014-09-01

    Full Text Available Bacterial pollution is a great risk for human health. Nanotechnology offers a way to develop new inorganic antibacterial agents. Nano-inorganic metal oxide has a potential to reduce bacterial contamination. MgO is an important inorganic oxide and has been widely used in many fields. Many studies have shown that MgO nanoparticles have good antibacterial activity. Therefore, in this paper, the main synthesis methods, antibacterial activity and antibacterial mechanisms of MgO nanoparticles are reviewed.

  20. Unexpected Stoichiometries in Mg-O System under High Pressure

    OpenAIRE

    Zhu, Qiang; Oganov, Artem R.; Lyakhov, Andriy O.

    2012-01-01

    Using ab initio evolutionary simulations, we explore all the possible stoichiometries for Mg-O system at pressures up to 850 GPa. In addition to MgO, our calculations find that two extraordinary compounds MgO2 and Mg3O2 become thermodynamically stable at 116 GPa and 500 GPa, respectively. Detailed chemical bonding analysis shows large charge transfer in all magnesium oxides. MgO2 contains peroxide ions [O-O]2-, while non-nuclear electron density maxima play the role of anions in the electride...

  1. 12Cao-7Al2o3 Electride Hollow Cathode

    Science.gov (United States)

    Rand, Lauren P. (Inventor); Williams, John D. (Inventor); Martinez, Rafael A. (Inventor)

    2016-01-01

    The use of the electride form of 12CaO-7Al.sub.2O.sub.3, or C12A7, as a low work function electron emitter in a hollow cathode discharge apparatus is described. No heater is required to initiate operation of the present cathode, as is necessary for traditional hollow cathode devices. Because C12A7 has a fully oxidized lattice structure, exposure to oxygen does not degrade the electride. The electride was surrounded by a graphite liner since it was found that the C12A7 electride converts to it's eutectic (CA+C3A) form when heated (through natural hollow cathode operation) in a metal tube.

  2. Remembrance for Prof. Antonio Cao and Prof. Renzo Galanello

    Directory of Open Access Journals (Sweden)

    Paolo Moi

    2014-09-01

    Full Text Available In less than one year Antonio Cao (Cagliari, May 4th 1929 - Cagliari, June 21st 2012 and Renzo Galanello (Parrano, July 21st 1948 - Cagliari, May 13th 2013, two amongst the greatest scientists in the fields of Pediatrics, Hematology and Thalassemia, have passed away. Their deaths are an enormous loss for all of us in the Hospital for Microcitemias in Cagliari, but also for the whole Italian and International scientific community, who recognized and admired their leadership. During the funeral ceremonies held in our Hospital where both spent the greatest part of their lives, the most touching words were those pronounced by the patients who were cured by and benefited of the scrupulous medical care of our colleagues for decades from their infancy to adulthood...

  3. Interstitial Fe in MgO

    CERN Document Server

    Mølholt, T E; Gunnlaugsson, H P; Svane, A; Masenda, H; Naidoo, D; Bharuth-Ram, K; Fanciulli, M; Gislason, H P; Johnston, K; Langouche, G; Ólafsson, S; Sielemann, R; Weyer, G

    2014-01-01

    Isolated Fe-57 atoms were studied in MgO single-crystals by emission Mossbauer spectroscopy following implantation of Mn-57 decaying to Fe-57. Four Mossbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. Two components represent Fe atoms substituting Mg as Fe2+ and Fe3+, respectively; a third component is due to Fe in a strongly implantation-induced disturbed region. The fourth component, which is the focus of this paper, can be assigned to Fe at an interstitial site. Comparison of its measured isomer shift with ab initio calculations suggests that the interstitial Fe is located on, or close to, the face of the rock-salt MgO structure. To harmonize such an assignment with the measured near-zero quadrupole interaction a local motion process (cage motion) of the Fe has to be stipulated. The relation of such a local motion as a starting point for long range diffusion is discussed.

  4. Fabrication and spectroscopic properties of transparent Nd3+:MgO and Er3+:MgO ceramics

    International Nuclear Information System (INIS)

    We present the results of the development and comprehensive characterization of fully densified Er3+:MgO and Nd3+:MgO transparent ceramics fabricated from specially formulated nanopowders. Also presented are the spectroscopic characterization results (absorption, fluorescence and emission lifetimes) of Er3+ and Nd3+ dopant ions in MgO in the temperature range 10 to 300 K. To the best of our knowledge, this is the first reported successful demonstration of bulk MgO host material doped with rare earth (RE) ions. Spectroscopic results are indicative of a single-site RE ion incorporation with a nearly perfect single crystalline environment within the MgO ceramic grains. The results are presented with major emphasis on potential laser application and the outlook for substantially improved laser power scaling at room temperature based on the unique thermal properties of the host material. (letters)

  5. Development of CaO- and MgO-swelling cements into usage maturity for cementation of natural gas underground storage wells and natural gas production wells. Final report; Entwicklung von CaO- und MgO-Quellzentren zur Einsatzreife fuer die Zementation von Erdgasspeicher- und Erdgasfoerderbohrungen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Ghofrani, R.

    1997-07-01

    The investigations conducted within the scope of this project are a consistent continuation of the work already performed at ITE, especially DGMK research projects 444-1 and 444-2. Essential parameters examined in the course of this project include the longterm stability behavior of CaO and MgO swelling cements under conditions similar to those prevailing in the borehole (storage medium, temperature, pressure), possibility of using more reactive magnesium oxides at static formation temperatures of 70 C to 120 C, and the expansion behavior of CaO swelling cements after being subjected to realistic shear, temperature, and compressive stress in a circulation system. For subjecting the cement slurry to realistic shear stress, a circulation system which operates at temperatures up to 150 C, heating rates up to 2.5 C/min, pressures up to 15 MPa, and volume flow rates up to 390 l/min was designed, constructed, and put into operation. (orig./HS) [Deutsch] Die Untersuchungen im Rahmen dieses Projektes stellen eine konsequente Fortsetzung der am ITE bereits durchgefuehrten Arbeiten, insbesondere der DGMK-Forschungsvorhaben 444-1 und 444-2, dar. Wesentliche Untersuchungsgroessen im Rahmen dieses Vorhabens sind das Langzeitstabilitaetsverhalten von CaO- und MgO-Quellzementen unter bohrlochaehnlichen Bedingungen (Lagerungsmedium, Temperatur, Druck), Einsetzbarkeit von mehr reaktiven Magnesiumoxiden bei statischen Gebirgstemperaturen von 70 [ C] bis 120 [ C] und das Ausdehnungsverhalten von CaO-Quellzementen nach einer praxisrelevanten Scher-, Temperatur- und Druckbelastung in einer Zirkulationsanlage. Zur praxisgerechten Scherbelastung des Zementschlammes wurde eine Zirkulationsanlage konzipiert, gebaut und in Betrieb genommen, die Temperaturen bis 150 [ C] bei Aufheizraten bis 2,5 [ C/min], Druecke bis 15 [MPa] und Volumenstroeme bis 390 [l/min] ermoeglicht. (orig./S)

  6. Electrodeposition of Ca Metal in CaCl2-CaO Molten Salt

    Institute of Scientific and Technical Information of China (English)

    GUO; Jun-kang; WANG; Chang-shui; CAO; Long-hao; OUYANG; Ying-gen

    2013-01-01

    To realize the continuouscalciothermic reduction in molten salts,the electrodeposition behavior of Ca metal in CaCl2-CaO molten salt was investigated by cylic voltammetry.The cyclic voltammograms at the scan rate of 100 mV/s are shown in Fig.1.As is shown,the electrodeposition potential of Ca deviated from-1.66 V to-0.97 V after CaO was added to molten CaCl2 and the decomposition of CaO

  7. Template synthesis and characteristics of nanoparticle MgO

    Directory of Open Access Journals (Sweden)

    A. Bagheri Gh.

    2015-10-01

    Full Text Available Oxide nanoparticles can exhibit unique physical and chemical properties due to their limited size and a high density of corner or edge surface sites. In this study, MgO nanoparticle was synthesized using Mg(CH3COO2 and hexamethylenetetramine as starting materials. The structure and optical properties of these particles are investigated by using X-ray diffraction (XRD, scanning electron microscopy (SEM and UV-Visible absorption. The XRD analysis discloses that MgO nanoparticle is successfully synthesized. Dispersive analysis of X-RAY (EDAX was used to characterize the size and morphology of the MgO nanoparticle on the template. The morphology of MgO was nanospheres.

  8. Production metallic 26Mg from 26MgO and the synthesis new isotope of 265Bh

    International Nuclear Information System (INIS)

    The metallicion beam is of importance for production of heavy elements by heavy-ion fusion evaporation reactions. In order to try to synthese a new superheavy nuclide 265Bh (Z=107), a reaction of 243Am target with 26Mg ion beam is selected to produce new isotope 265Bh. The preparation and production of this rare and extremely expensive isotope 26Mg used for ion beam substance will be the key problem in synthesizing experiment of 265Bh. The available chemical form of isotope 26Mg in commercial product usually is oxide or other compound, which are not required in our experiment. They need to be transformed to metal form as a proper working substance in ion source. There is a lot of technique to prepare metallic 26Mg from its oxide. Pidgeon method of them is the most common technique. Its basic principle is that the metallic 26Mg could be reduced from 26MgO with FeSi (Ferro-Silicon): 226MgO + 2CaO + FeSi→226Mg + Ca2SiO4 + Fe The set-up for producing 26Mg consists of a tubal electric oven, a sealed stainless steel tube connected with a vacuum pump, and a tantalum foil put in inner wall of the tube and used to collect 26Mg sample. The bottom of the tube is filled with the mixture of 26MgO, CaO and FeSi powder. It is heated at 1200 degree C for the reduction. The top part of the tube is cooled by circular water. In this case, temperature grads are formed along the tube. So the magnesium vapour produced from the reaction will be condensed to crystal on the surface of tantalum collection foil where the temperature is suitable for the condensation of 26Mg vapour (∼400-600 degree C). In the experiment, several conditions such as temperature, reduction. time, proportion of the mixture component etc are investigated, and-the optimal conditions are obtained. At 1200 degree C, the production rate of metallic 26Mg is ∼0.5 g/h. The reduction efficiency is larger than 90% and the chemistry purity of magnesium is 99.9%. In conclusion, 26Mg with a good quality has been obtained

  9. Measurement of secondary ionization coefficient of CaO film electrode

    Science.gov (United States)

    Suzuki, Susumu; Kashiwagi, Yasuhide; Itoh, Haruo

    2013-02-01

    The secondary ionization coefficient γ of a CaO film electrode is investigated taking into account the difference in breakdown voltage obtained by repeated voltage applications. Such measurement is performed under a sinusoidal voltage of 0.5 Hz. If the CaO film electrode acts as the cathode, breakdown voltage gradually decreases and converges to an almost constant value after several breakdowns. From the obtained results, the γ of the CaO film electrode is determined for each breakdown using Townsend's criterion. The γ in the first breakdown is lower than those in subsequent breakdowns, particularly in the steady state. The difference in γ is considered to originate from accumulated charges on the CaO film electrode. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  10. Template synthesis and characteristics of nanoparticle MgO

    OpenAIRE

    A. Bagheri Gh.; Z. Mirjani Kahaki

    2015-01-01

    Oxide nanoparticles can exhibit unique physical and chemical properties due to their limited size and a high density of corner or edge surface sites. In this study, MgO nanoparticle was synthesized using Mg(CH3COO)2 and hexamethylenetetramine as starting materials. The structure and optical properties of these particles are investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible absorption. The XRD analysis discloses that MgO nanoparticle is successful...

  11. On Interpreting the Photoelectron Spectra of MgO

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Arnold, James (Technical Monitor)

    2001-01-01

    The (sup 2)Sigma(+) and (sup 2)Pi states of MgO(-) and the (sup 1)Sigma(+), (sup 1)Pi, and (sup 3)Pi states of MgO are studied using the averaged coupled-pair functional (ACPF) approach. The computed spectroscopic constants are in good agreement with the available experimental data. The computed Franck-Condon factors and photodetachment overlaps are compared with experiment.

  12. Phase Composition and Thermal Expansion of CaO Stabilised ZrO2 Refactories

    Institute of Scientific and Technical Information of China (English)

    ZHAOShike; WUJingyuan; 等

    2000-01-01

    In this,phase compsition and thermal expansion behaviour of CaO Stabilised refractories were studied,Special attention was paid to the expasion behaviour of three materials with different phase composition,The research results indicated that the expansion behaviour could be improved by modifying the stabilization of ZrO2,which thus leads to the increase in the thermal shock resistance and possibly eroion resistace of as-obtained CaO stabilised ZrO material.

  13. Secondary Ionization Coefficient of MgO and Accumulated Charge

    Science.gov (United States)

    Suzuki, Susumu; Sekizawa, Takashi; Kashiwagi, Yasuhide; Itoh, Haruo

    2011-10-01

    An experimental study on Townsend's secondary ionization coefficient γ of MgO is carried out in accordance with a previously reported sequential procedure. A sinusoidal voltage is applied between the MgO film electrode and a stainless-steel electrode in the frequency range of 0.1 Hz-2 kHz. The breakdown voltage is determined from the observed waveforms of applied voltage and accumulated charge on the MgO film electrode. The influence on the breakdown voltage of the voltage induced by the accumulated charge is investigated. We found that the accumulated charge does not affect the breakdown voltage at low frequency or the DC voltage, but it affects the breakdown voltage at high frequency. Using the breakdown voltage, we determine Townsend's secondary ionization coefficient γ of MgO. The obtained γ for MgO in the study is compared with other reported values. It is found that γ for MgO is larger than those of metallic electrodes.

  14. Pulsed laser deposition of SiO2 - P2O5 - CaO - MgO glass coatings on titanium substrates

    Directory of Open Access Journals (Sweden)

    Joanni Ednan

    2004-01-01

    Full Text Available Thin films of bioactive glass-ceramic have been deposited on titanium substrates by the Pulsed Laser Deposition (PLD technique under different experimental conditions. The effect of parameters such as deposition pressure and temperature of heat treatments was studied. The microstructure and the crystalline phases of the coatings were characterized using SEM, EDX and XRD analysis; the phases present were titanium oxides, calcium magnesium silicates and phosphates. The adhesion of the as-deposited films has been examined by scratch tests. The interfacial adhesion of the coatings was better when the deposition was performed at low pressure. Samples were immersed in simulated body fluid (SBF, and a calcium-phosphate precipitate was observed on the surface of less crystallized samples, suggesting that there is some relationship between surface reactivity and crystallinity.

  15. THERMODYNAMIC AND KINETIC PARAMETERS OF MIXTURES DESULFURIZING THE MADE WITH CaO, MgO, SiO2 AND CaF2

    Directory of Open Access Journals (Sweden)

    Felipe Nylo de Aguiar

    2012-09-01

    Full Text Available This paper presents an analysis of the kinetics and thermodynamics of marble residue mixtures utilisation on desulfurization of pig iron. The desulfurization was carried out using lime, marble residue, fluorite and pig iron. Different mixtures of these materials were added into a bath of pig iron at 1,450°C. Metal samples were collected via vacuum samplers at times of 5, 10, 15, 20 and 30 minutes, in order to check the variation of sulfur content. Based on the results of chemical analysis of the metal and the desulfurizer mixture, the sulfide capacity of mixtures, the sulfur partition coefficient and the sulfur mass transport coefficient values were calculated.The results show the technical feasibility of using marble waste as desulfurizer agent.

  16. The interaction of Fe thin layers between MgO(100)-MgO and MgO(100)-Ag surfaces

    OpenAIRE

    Dézsi, I.; Fetzer, Cs.; Tanczikó, F.; Nakanishi, A.; Kobayashi, T.

    2011-01-01

    The atomic interaction and magnetic properties of ultrathin Fe films grown on cleaved and polished MgO(100) surfaces were studied by conversion electron M\\"{o}ssbauer spectroscopy (CEMS) in broad temperature range. Fe with different layer thickness was deposited on MgO substrates. The layers were formed on polished and cleaved substrate surfaces at RT. The analysis of the spectra showed no Fe-O$^{2-}$ interaction in MgO/Fe interface. Iron layers showed different magnetic anisotropy depending ...

  17. Preparation and Properties of High Area MgO Support and MoO3/MgO Catalyst

    Czech Academy of Sciences Publication Activity Database

    Gulková, Daniela; Šolcová, Olga; Vít, Zdeněk; Zdražil, Miroslav

    2003. s. A2.137. [European Catalysis Forum EuropaCat - VI. 31.08.2003-04.09.2003, Innsbruck] R&D Projects: GA ČR GA104/01/0544 Institutional research plan: CEZ:AV0Z4072921 Keywords : MgO support * MoO3/ MgO catalyst * HDS and HN Subject RIV: CF - Physical ; Theoretical Chemistry

  18. CAOS: the nested catchment soil-vegetation-atmosphere observation platform

    Science.gov (United States)

    Weiler, Markus; Blume, Theresa

    2016-04-01

    Most catchment based observations linking hydrometeorology, ecohydrology, soil hydrology and hydrogeology are typically not integrated with each other and lack a consistent and appropriate spatial-temporal resolution. Within the research network CAOS (Catchments As Organized Systems), we have initiated and developed a novel and integrated observation platform in several catchments in Luxembourg. In 20 nested catchments covering three distinct geologies the subscale processes at the bedrock-soil-vegetation-atmosphere interface are being monitored at 46 sensor cluster locations. Each sensor cluster is designed to observe a variety of different fluxes and state variables above and below ground, in the saturated and unsaturated zone. The numbers of sensors are chosen to capture the spatial variability as well the average dynamics. At each of these sensor clusters three soil moisture profiles with sensors at different depths, four soil temperature profiles as well as matric potential, air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels are measured continuously. In addition, most sensors also measure temperature (water, soil, atmosphere) and electrical conductivity. This setup allows us to determine the local water and energy balance at each of these sites. The discharge gauging sites in the nested catchments are also equipped with automatic water samplers to monitor water quality and water stable isotopes continuously. Furthermore, water temperature and electrical conductivity observations are extended to over 120 locations distributed across the entire stream network to capture the energy exchange between the groundwater, stream water and atmosphere. The measurements at the sensor clusters are complemented by hydrometeorological observations (rain radar, network of distrometers and dense network of precipitation gauges) and linked with high resolution meteorological models. In this

  19. Intense 31–35Ar beams produced with a nanostructured CaO target at ISOLDE

    International Nuclear Information System (INIS)

    Highlights: • A nanometric mesoporous CaO powder was developed and studied in terms of sintering. • For the first time a nanostructured target material was operated at ISOLDE. • Unlike past CaO targets, stable yields over time of n-deficient argon were delivered. • Higher (exotic) Ar yields were obtained at lower temperatures and proton intensities. -- Abstract: At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which is connected to an ionizer, from which the charged isotopes are extracted and delivered for physics experiments. Calcium oxide (CaO) powder targets have been used to produce mainly neutron deficient argon and carbon RIBs over the past decades. Such targets presented unstable yields, either decaying over time or low from the beginning of operation. These problems were suspected to come from the degradation of the target microstructure (sintering due to high temperature and/or high proton intensity). In this work, a CaO microstructural study in terms of sintering was conducted on a nanostructured CaO powder synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE in terms of the CaO target production, handling and operation in order to produce and maintain the nanostructured CaO. The new target, the first nanostructured target to be operated at ISOLDE, showed improved yields of (exotic) Ar and more importantly a stable yield over the whole operation time, while operating with lower temperatures. This contradicts the ISOL paradigm of using the highest possible temperature regardless of the target’s microstructure degradation

  20. Size effects in MgO cube dissolution.

    Science.gov (United States)

    Baumann, Stefan O; Schneider, Johannes; Sternig, Andreas; Thomele, Daniel; Stankic, Slavica; Berger, Thomas; Grönbeck, Henrik; Diwald, Oliver

    2015-03-10

    Stability parameters and dissolution behavior of engineered nanomaterials in aqueous systems are critical to assess their functionality and fate under environmental conditions. Using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, we investigated the stability of cubic MgO particles in water. MgO dissolution proceeding via water dissociation at the oxide surface, disintegration of Mg(2+)-O(2-) surface elements, and their subsequent solvation ultimately leads to precipitation of Mg(OH)2 nanosheets. At a pH ≥ 10, MgO nanocubes with a size distribution below 10 nm quantitatively dissolve within few minutes and convert into Mg(OH)2 nanosheets. This effect is different from MgO cubes originating from magnesium combustion in air. With a size distribution in the range 10 nm ≤ d ≤ 1000 nm they dissolve with a significantly smaller dissolution rate in water. On these particles water induced etching generates (110) faces which, above a certain face area, dissolve at a rate equal to that of (100) planes.1 The delayed solubility of microcrystalline MgO is attributed to surface hydroxide induced self-inhibition effects occurring at the (100) and (110) microplanes. The present work underlines the importance of morphology evolution and surface faceting of engineered nanomaterials particles during their dissolution. PMID:25668706

  1. Use of porous MgO in pyrochemical applications

    International Nuclear Information System (INIS)

    Pyrochemical methods for the extraction of transuranic elements from light water reactor spent fuel require a reduction step in which the oxide fuel is reduced to metals by Li in molten LiCl. The Li2O formed is electrolytically reduced to metal in a cell that uses a carbon (or inert) anode and a Li cathode to recycle the salt and minimize the waste. Use of a carbon anode causes carbon dust that interferes with the process. Moreover, current efficiency is reduced as a result of oxidation of Li to Li2O by CO2. A porous MgO shroud around the anode was found to obviate these problems. Porous MgO crucibles and rectangular bar specimens were fabricated from MgO powders (electrically fused MgO, reagent grade MgO were mixed in appropriate combinations with a binder and lubricant). Particle size, force applied to the powders during cold pressing, and sintering temperature were varied to achieve a total porosity of >45% (mostly open porosity) and to control pore size and pore distribution. Mercury intrusion porosimetry was used to determine the pore size and pore size distribution. Flexural strength is observed to be proportional to the square root of pore size, which is consistent with fracture mechanics

  2. New pyrometallurgical process of EAF dust treatment with CaO addition

    Institute of Scientific and Technical Information of China (English)

    Romchat Chairaksa-Fujimoto; Yosuke Inoue; Naoyoshi Umeda; Satoshi Itoh; Tetsuya Nagasaka

    2015-01-01

    The non-carbothermic zinc pyrometallurgical processing of electric arc furnace (EAF) dust was investigated on a laboratory scale. The main objective of this process was to convert highly stable zinc ferrite (ZnFe2O4), which accounts for more than half of total zinc in the EAF dust, into ZnO and Ca2Fe2O5 by CaO addition. The EAF dust was mixed with CaO powder in various ratios, pressed into pellets, and heated in a muffle furnace in air at temperatures ranging from 700 to 1100°C for a predetermined holding time. All ZnFe2O4 was transformed into ZnO and Ca2Fe2O5 at a minimum temperature of 900°C within 1 h when sufficient CaO to achieve a Ca/Fe molar ratio of 1.1 was added. However, at higher temperatures, excess CaO beyond the stoichiometric ratio was required because it was consumed by reactions leading to the formation of compounds other than ZnFe2O4. The evaporation of halides and heavy metals in the EAF dust was also studied. These components could be pref-erentially volatilized into the gas phase at 1100°C when CaO was added.

  3. Microstructural and textural characterization in MgO thin film using HRTEM

    International Nuclear Information System (INIS)

    The microstructural and texture evolution of MgO protective films deposited on Si and glass substrates by ebeam evaporation were investigated. MgO films on both types of substrates consisted of a well developed columnar structure showing texture in the cross sectional view and a triangle shape in the plane view. It was found that there is amorphous MgO between each columnar, which occupies 8-25% in the MgO films. The electron energy loss spectroscopy (EELS) spectrum of amorphous MgO showed features of chemical states and electronic structures different from those of crystalline MgO.

  4. Soluble salts addition modifies MgO hydration

    International Nuclear Information System (INIS)

    Magnesium oxide (MgO) show great technological interest on refractories due to its high refractoriness, basic slag corrosion resistance and competitive cost. However, the hydration reaction of MgO produces magnesium hydroxide. This reaction generates a significant volumetric expansion that can lead to material breakdown inhibiting its use in refractory castables. This reaction can be affected by several factors such as magnesia source, purity, calcination temperature, pH, CaO/SiO2 ratio and agitation speed. In the present work, soluble salts (CaCl2 and MgCl2) were used in MgO aqueous suspensions (caustic and sinter). The results were evaluated by means of techniques of degree of hydration (termogravimetric), Scanning electron microscopy, apparent volumetric expansion and x-ray Diffraction which showed that the degree of hydration was noticeably less to sinter aqueous and the expansive effects were less with the addition of CaCl2. (author)

  5. Fabrication of Single Crystal MgO Capsules

    Science.gov (United States)

    Danielson, Lisa

    2012-01-01

    A method has been developed for machining MgO crystal blocks into forms for containing metallic and silicate liquids at temperatures up to 2,400 C, and pressures up to at least 320 kilobars. Possible custom shapes include tubes, rods, insulators, capsules, and guides. Key differences in this innovative method include drilling along the crystallographic zone axes, use of a vibration minimizing material to secure the workpiece, and constant flushing of material swarf with a cooling medium/lubricant (water). A single crystal MgO block is cut into a section .5 mm thick, 1 cm on a side, using a low-speed saw with a 0.004 blade. The cut is made parallel to the direction of cleavage. The block may be cut to any thickness to achieve the desired length of the piece. To minimize drilling vibrations, the MgO block is mounted on a piece of adhesive putty in a vise. The putty wad cradles the bottom half of the entire block. Diamond coring tools are used to drill the MgO to the desired custom shape, with water used to wet and wash the surface of swarf. Compressed air may also be used to remove swarf during breaks in drilling. The MgO workpiece must be kept cool at all times with water. After all the swarf is rinsed off, the piece is left to dry overnight. If the workpiece is still attached to the base of the MgO block after drilling, it may be cut off by using a diamond cutoff wheel on a rotary hand tool or by using a low-speed saw.

  6. Biomass gasification bottom ash as a source of CaO catalyst for biodiesel production via transesterification of palm oil

    International Nuclear Information System (INIS)

    Highlights: • CaO catalyst was successfully developed from wood gasification bottom ash. • CaCO3 in bottom ash can be converted to CaO catalyst by calcination. • CaO catalysts derived from bottom ash exhibited high activity towards transesterification. • CaO catalysts derived from bottom ash can be reutilized up to four times. - Abstract: The main aim of this research is to develop environmentally and economically benign heterogeneous catalysts for biodiesel production via transesterification of palm oil. For this propose, calcium oxide (CaO) catalyst has been developed from bottom ash waste arising from woody biomass gasification. Calcium carbonate was found to be the main component in bottom ash and can be transformed into the active CaO catalyst by simple calcination at 800 °C without any chemical treatment. The obtained CaO catalysts exhibit high biodiesel production activity, over 90% yield of methyl ester can be achieved at the optimized reaction condition. Experimental kinetic data fit well the pseudo-first order kinetic model. The activation energy (Ea) of the transesterification reaction was calculated to be 83.9 kJ mol−1. Moreover, the CaO catalysts derived from woody biomass gasification bottom ash can be reutilized up to four times, offering the efficient and low-cost CaO catalysts which could make biodiesel production process more economic and environmental friendly

  7. Shock-induced temperatures of MgO

    OpenAIRE

    Svendsen, Bob; Ahrens, Thomas J.

    1987-01-01

    Shock-compressed MgO radiates thermally at temperatures between 2900 and 3700 K in the 170–200 GPa pressure range. A simple energy-transport model of the shocked-MgO-targets distinguishes between different shock-induced radiation sources in these targets and provides estimates of spectral absorption-coefficients, α_(λMgO), for shocked MgO (e.g. at 203 GPa, α_(λMgO) ~ 630, 7500, 4200 and 3800 m^(−1), at 450, 600, 750 and 900 nm, respectively). The experimentally inferred temperatures of the sh...

  8. Effect of CaO content on residual stress of CAS glass-ceramic

    Institute of Scientific and Technical Information of China (English)

    XIE Jun; CHENG Jin-shu; LONG Xin-jiang; YANG Shu-zhen

    2006-01-01

    The mismatch in thermal expansion coefficient between crystalline phase and glass phase can result in large thermal stresses during thermal processing,as well as the low thermal conductivity,which is the most troublesome in the production of the CaO-Al2O3-SiO2 glass-ceramic. CaO content may influence the residual stress in the system. Therefore X-ray diffraction (XRD) 'sin2ψ' method was used to calculate the residual stress in samples containing various contents of CaO. The relationship between CaO content and residual stress in CAS system was investigated. Finally reasons causing such residual stress were analyzed.

  9. Effect of CaO from Mineral and Pure Oxide on Nano structure Cordierite

    International Nuclear Information System (INIS)

    Cordierite was synthesized via glass-route using mineral and pure oxide material. Kaolin, talc, dolomite, magnesia, alumina, silica, and calcium oxide were mixed and melted at 1540 degree Celsius for 4 h. CaO from mineral and pure oxide was added in order to investigate the properties of each material in cordierite system. Sample was characterized using XRD analysis, dilatometer testing and SEM. XRD result shows that when 5 wt % CaO from mineral (C5 Min) was added and sintered at 900 degree Celsius, α-cordierite exist as major phase and anorthite as a minor phase. While for a sample consists of 5 wt % CaO from pure oxide (C5 Ox), α-cordierite was present as major phases α-cordierite and anorthite as minor phases. Crystallite sizes of each material were in nano range and crystallite size of C5 Ox was less than C5 Min. (author)

  10. [Quantitative estimation of CaO content in surface rocks using hyperspectral thermal infrared emissivity].

    Science.gov (United States)

    Zhang, Li-Fu; Zhang, Xue-Wen; Huang, Zhao-Qiang; Yang, Hang; Zhang, Fei-Zhou

    2011-11-01

    The objective of the present paper is to study the quantitative relationship between the CaO content and the thermal infrared emissivity spectra. The surface spectral emissivity of 23 solid rocks samples were measured in the field and the first derivative of the spectral emissivity was also calculated. Multiple linear regression (MLR), principal component analysis (PCR) and partial least squares regression (PLSR) were modeled and the regression results were compared. The results show that there is a good relationship between CaO content and thermal emissivity spectra features; emissivities become lower when CaO content increases in the 10.3-13 mm region; the first derivative spectra have a better predictive ability compared to the original emissivity spectra. PMID:22242490

  11. Simultaneous carbonation and sulfation of CaO in Oxy-Fuel CFB combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C. [School of Energy and Power Engineering, North China Electric Power University, Baoding City, Hebei Province (China); Jia, L.; Tan, Y. [CanmetENERGY, 1 Haanel Drive, Ottawa, Ontario, K1A 1M1 (Canada)

    2011-10-15

    For anthracites and petroleum cokes, the typical combustion temperature in a circulating fluidized bed (CFB) is > 900 C. At CO{sub 2} concentrations of 80-85 % (typical of oxy-fuel CFBC conditions), limestone still calcines. When the ash which includes unreacted CaO cools to the calcination temperature, carbonation of fly ash deposited on cool surfaces may occur. At the same time, indirect and direct sulfation of limestone also will occur, possibly leading to more deposition. In this study, CaO was carbonated and sulfated simultaneously in a thermogravimetric analyzer (TGA) under conditions expected in an oxy-fuel CFBC. It was found that temperature, and concentrations of CO{sub 2}, SO{sub 2}, and especially H{sub 2}O are important factors in determining the carbonation/sulfation reactions of CaO. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Theoretical study on the reaction mechanism of CH4 with CaO

    International Nuclear Information System (INIS)

    The reaction pathways and energetics for the reaction of methane with CaO are discussed on the singlet spin state potential energy surface at the B3LYP/6-311+G(2df,2p) and QCISD/6-311++G(3df,3pd)//B3LYP/6-311+G(2df,2p) levels of theory. The reaction of methane with CaO is proposed to proceed in the following reaction pathways: CaO + CH4→ CaOCH4→ [TS] → CaOH + CH3, CaO + CH4→ OCaCH4→ [TS] → HOCaCH3→ CaOH + CH3 or [TS] → CaCH3OH → Ca + CH3OH, and OCaCH4→ [TS] → HCaOCH3→ CaOCH3 + H or [TS] → CaCH3OH → Ca + CH3OH. The gas-phase methane-methanol conversion by CaO is suggested to proceed via two kinds of important reaction intermediates, HOCaCH3 and HCaOCH3, and the reaction pathway via the hydroxy intermediate (HOCaCH3) is energetically more favorable than the other one via the methoxy intermediate (HCaOCH3). The hydroxy intermediate HOCaCH3 is predicted to be the energetically most preferred configuration in the reaction of CaO + CH4. Meanwhile, these three product channels (CaOH + CH3, CaOCH3 + H and Ca + CH3OH) are expected to compete with each other, and the formation of methyl radical is the most preferable pathway energetically. On the other hand, the intermediates HCaOCH3 and HOCaCH3 are predicted to be the energetically preferred configuration in the reaction of Ca + CH3OH, which is precisely the reverse reaction of methane hydroxylation

  13. Noncontact atomic force and Kelvin probe force microscopy on MgO(100) and MgO(100)-supported Ba

    Science.gov (United States)

    Pang, Chi Lun; Sasahara, Akira; Onishi, Hiroshi

    2016-08-01

    Atomically-flat MgO(100) surfaces were prepared by sputtering and annealing. Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM) were used to characterize the MgO(100) surfaces. The NC-AFM images revealed the presence of point defects on an atomically-resolved surface. The surface potential at these point defects, as well as features such as step edges and deposited Ba nanoparticles were mapped using KPFM. The Kelvin images show that the surface potential increases at the point defects and at the step edges. On the other hand, a decrease in the potential was found over Ba nanoparticles which can be explained by electron charge transfer from the Ba to the MgO.

  14. Formation and operation of CaO coating in a self-healing mode

    International Nuclear Information System (INIS)

    Based on analysis of obtained results and reference reviews a phenomenological model of interaction between the components in Li [Ca]-V [O] system is presented. The model depicts a cyclic process. The cycle consists of: (I) oxygen transfers from a vanadium into lithium and calcium depositions on the vanadium surface; (II) CaO layer grows while simultaneously titanium oxide dissolve and oxygen and titanium spread into the solid solution; (III) the liquid metal penetrates into the solid metal according to the mechanism of reactionary diffusion; (IV) meta-stable triple oxide decays; external CaO oxide recovers

  15. Application of Chinese Jun-Cao technique for the production of Brazilian Ganoderma lucidum strains

    Directory of Open Access Journals (Sweden)

    Leonardo do Nascimento Rolim

    2014-06-01

    Full Text Available Ganoderma lucidum is a medicinal mushroom traditionally used in China against a wide range of diseases such as cancer and also for its prevention. In this work, commercial Chinese strains G. lucidum were compared to wild Brazilian strains aiming to determine the cultivation potential through the use of Jun-Cao. Six formulations were tested and the strains presented good response to the applied method. In general, the mixture between the grass and wood was well suited for the basidiomycetes, contributing to the preparation of substrates that generated better results in Jun Cao.

  16. The electronic structure of NaF and CaO studied by Compton scattering

    International Nuclear Information System (INIS)

    Compton profiles of NaF and CaO single crystals were measured along the [100] and [110] directions using 60 keV gamma rays. A theoretical analysis based on Compton profiles and autocorrelation functions was performed by application of the augmented plane wave (APW) and linear combination of atomic orbitals (LCAO) methods. In the case of NaF both theories agree well with each other but their results differ in a characteristic manner from the experiment. For CaO a good agreement of the APW results and experiment especially for the difference quantities is found whereas the LCAO model yields less satisfying results in this case. (orig.)

  17. Nature et propriétés des espèces en solution dans le système K2O-Na2O-SiO2-Al2O3-H2O-HCI : contribution expérimentale

    OpenAIRE

    Pascal, Marie-Lola

    1984-01-01

    ON A ETUDIE LES EQUILIBRES ENTRE DES SOLUTIONS AQUEUSES CHLORUREES OU NON ET DES MINERAUX DU SYSTEME SIO::(2)-AL::(2)O::(3)-NA::(2)O-K::(2)O. LES DONNEES THERMODYNAMIQUES SUR LES PHASES SOLIDES ET LA DISTRIBUTION DES ESPECES ALCALINES ENTRE IONS ET MOLECULES DANS LES SOLUTIONS CONCENTREES DE CHLORURES DE SODIUM ET DE POTASSIUM SONT L'OBJET DE LA PREMIERE PARTIE; LA SECONDE PARTIE TRAITE DE L'IMPORTANCE DES COMPLEXES QUE LES ALCALINS FORMENT AVEC LA SILICE ET SURTOUT L'ALUMINE DANS LE SYSTEME ...

  18. Highly (100) oriented MgO growth on thin Mg layer in MTJ structure

    Science.gov (United States)

    Jimbo, K.; Nakagawa, S.

    2011-01-01

    In order to apply Stress Assisted Magnetization Reversal (SAMR) method to perpendicular magnetoresistive random access memory (p-MRAM) with magnetic tunnel junction (MTJ) using MgO (001) oriented barrier layer, multilayer of Ta/ Terfenol-D/ Mg/ MgO and Ta/ Terfenol-D/ MgO were prepared. While the MgO layer, deposited directly on the Terfenol-D layer, did not show (100) orientatin, very thin metallic Mg layer, deposited prior to the MgO deposition, was effective to attain MgO (100) orientation. The crystalline orientation was very weak without Mg, however, the multilayer with Mg showed very strong MgO(100) peak and the MgO orientation was shifted depending on the Mg thickness.

  19. Dependence of tunnel magnetoresistance in MgO based magnetic tunnel junctions on Ar pressure during MgO sputtering

    OpenAIRE

    Ikeda, Shoji; Hayakawa, Jun; Lee, Young Min; Sasaki, Ryutaro; Meguro, Toshiyasu; Matsukura, Fumihiro; Ohno, Hideo

    2005-01-01

    We investigated dependence of tunnel magnetoresistance effect in CoFeB/MgO/CoFeB magnetic tunnel junctions on Ar pressure during MgO-barrier sputtering. Sputter deposition of MgO-barrier at high Ar pressure of 10 mTorr resulted in smooth surface and highly (001) oriented MgO. Using this MgO as a tunnel barrier, tunnel magnetoresistance (TMR) ratio as high as 355% at room temperature (578% at 5K) was realized after annealing at 325 C or higher, which appears to be related to a highly (001) ori...

  20. Optimum Composition of CaO-SiO2-Al2O3-MgO Slag for Spring Steel Deoxidized by Si and Mn in Production

    Science.gov (United States)

    Yang, Hulin; Ye, Jiansong; Wu, Xiaoliang; Peng, Yongsheng; Fang, Yi; Zhao, Xinbing

    2016-04-01

    The relations between plasticity of inclusions and contents of oxygen, aluminum, and sulfur in molten steel were overall discussed by thermodynamics and FactSage software. Then, the optimum compositions of slag were obtained and the activities of components of refining slag system were analyzed. Finally, experiments were carried out based on the results of calculation. According to the relations, it could achieve better effect to improve basicity R ( R = CaO/SiO2 by mass pct) and C/ A ( C/ A = CaO/Al2O3 by mass pct) in the low melting temperature [≤1673 K (≤1400 °C)] region of refining slag as far as possible. For the CaO-SiO2-Al2O3-MgO slag, the optimum compositions are MgO: 5-9 pct, CaO: 47.4-50.2 pct, SiO2: 41.9-45.6 pct and Al2O3: ≤2.79 pct, respectively, in which the basicity is at the range of 1.0 to 1.19 and C/ A is above 9.0. It is proved by experiments that the plasticity of inclusions and the contents of [O], [Al], and [S] can be controlled effectively by the optimum composition of refining slag, and the high cleanness is achieved in spring wire rods.

  1. Position of Fe ions in MgO crystalline structure

    Directory of Open Access Journals (Sweden)

    Szczerba Jacek

    2015-03-01

    Full Text Available Magnesium oxide (MgO is one of the most important raw materials in many branches of industry. Magnesium oxide is a popular refractory raw material because of its high refractoriness and high resistance to basic slags and environment. In many cases, use of MgO is limited by its properties, especially the presence of secondary phases like iron oxides. The amount and distribution of iron oxides can strongly influence the technological properties of MgO and depend on the manufacturing method, particularly the heat-treatment process. The aim of the study was to evaluate the influence of the heat-treatment process on amount and distribution of iron ions in a magnesium oxide lattice. The 57Fe Mössbauer effect measurements of fused and sintered magnesium oxide samples doped by the iron oxide were conducted. Investigation reveals in both cases the presence of Fe2+ as well as Fe3+ ions. Fe2+ ions occupy Mg2+ octahedral sites in the MgO lattice, whereas the Fe3+ ions are located in highly distorted octahedral coordination. The amount of Fe2+ varies from around 66% for fused samples to 30% for sintered samples.

  2. Room temperature ferromagnetism in pristine MgO thin films

    International Nuclear Information System (INIS)

    Robust ferromagnetic ordering at, and well above room temperature is observed in pure transparent MgO thin films (3 is measured on a 170 nm thick film. The films above 500 nm are found to be diamagnetic. Ab initio calculations suggest that the ferromagnetism is mediated by cation vacancies.

  3. Thermically stimulated exoelectronic emissions and thermoluminescence of MgO

    International Nuclear Information System (INIS)

    In this work, studies were performed on the following topics: i) thermically stimulated exoelectronic emission (TSEE) in pure MgO single crystals ion implanted, submitted to thermal treatment with fast on slow cooling and water adsorption; ii) ultraviolet light effect on TSEE; iii) thermoluminescent emission; iv) crystallization of FeCoB amorphous alloys. (A.C.A.S.)

  4. Magnesium aluminate spinel precipitation in MgO

    Energy Technology Data Exchange (ETDEWEB)

    Berthelet, C.; Kingery, W.D.; Vandersande, J.B.

    1976-01-01

    Magnesium aluminate spinel precipitates forming in polycrystalline MgO containing 0.43 weight % Al and 0.031 weight % Al were examined by transmission electron microscopy after air quenching or rapid cooling. Precipitation in a variety of morphologies occurred at grain boundaries, low angle grain boundaries and dislocations. On reheating a virgin surface, precipitation occurs at temperatures above 730/sup 0/C.

  5. Lithium ion implantation effects in MgO (100)

    NARCIS (Netherlands)

    van Huis, MA; Fedorov, AV; van Veen, A; Labohm, F; Schut, H; Mijnarends, PE; Kooi, BJ; De Hosson, JTM; Triftshauser, W; Kogel, G; Sperr, P

    2001-01-01

    Single crystals of MgO (100) were implanted with 10(16) (6)Li ions cm(-2) at an energy of 30 keV. After ion implantation the samples were annealed isochronally in air at temperatures up to 1200K. After implantation and after each annealing step, the defect evolution was monitored with optical absorp

  6. Effect of partial carbonation on the cyclic CaO carbonation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Grasa, G.; Abanades, J.C.; Anthony, E.J. [CSIC, Zaragoza (Spain)

    2009-10-15

    CaO particles from the calcination of natural limestones can be used as regenerable solid sorbents in some CO{sub 2} capture systems. Their decay curves in terms of CO{sub 2} capture capacity have been extensively studied in the literature, always in experiments allowing particles to reach their maximum carbonation conversion for a given cycle. However, at the expected operating conditions in a CO{sub 2} capture system using the carbonation reaction, a relevant fraction of the CaO particles will not have time to fully convert in the carbonator reactor. This work investigates if there is any effect on the decay curves when CaO is only partially converted in each cycle. Experiments have been conducted in a thermobalance arranged to interrupt the carbonation reaction in each cycle before the end of the fast reaction period typical in the CaO-CO{sub 2} reaction. It is shown that, after the necessary normalization of results, the effective capacity of the sorbent to absorb CO{sub 2} during particle lifetime in the capture system slightly increases and CaO particles partially converted behave 'younger' than particles fully converted after every calcination. This has beneficial implications for the design of carbonation/calcination loops.

  7. Thermal diffusivity of sintered 12CaO-7Al2O3

    OpenAIRE

    Nikolić Pantelija M.; Luković D.; Savić S.; Urošević Dragan B.; Đurić S.

    2003-01-01

    The thermal diffusivity and some electrical transport properties of sintered 12CaO-7Al2O3 were determined using a photoacoustic method with a transmission detection configuration. The thermal diffusivity, coefficient of carrier diffusion and the surface recombination velocities were determined by fitting experimental spectra and theoretical photoacoustic amplitude and phase signals.

  8. INTERFACIAL DEFECTS IN NiO-ZrO2 (CaO) EUTECTIC

    OpenAIRE

    Dravid, V.; Notis, M.; Lyman, C.; Revcolevschi, A.; Bleris, G.

    1990-01-01

    Lamellar interfaces in the NiO-ZrO2(CaO) directionally solidified eutectic (DSE) have been investigated using electron optical techniques. Several characteristic interfacial defects have been analyzed and discussed invoking geometric arguments. Special attention is given to the topographical defects and their structural and functional characteristics.

  9. Thermodynamic Properties of Phosphorus Oxide in the 2CaO·SiO2-3CaO·P2O5 Solid Solution Saturated with MgO

    Science.gov (United States)

    Zhong, Ming; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

    2016-06-01

    Molten iron was equilibrated with various compositions of the 2CaO·SiO2-3CaO·P2O5 solid solution saturated with MgO with the oxygen partial pressure of 5.22 × 10-12 atm at 1823 K (1550 °C) and 1.41 × 10-11 atm at 1873 K (1600 °C). From the concentration of P in molten iron at equilibrium, the activity of P2O5 relative to the hypothetical pure liquid P2O5 was determined. The saturating MgO phase at equilibrium was detected by X-ray diffraction for each sample, and thus, the activity of 3MgO·P2O5 was also estimated. The activity of P2O5 and 3MgO·P2O5 increased with the increase of 3CaO·P2O5 content in the solid solution. In addition, the activity of P2O5 in the 2CaO·SiO2-3CaO·P2O5 solid solution saturated with MgO was larger than that saturated with CaO.

  10. Hydrometallurgical extraction of zinc from CaO treated EAF dust in ammonium chloride solution.

    Science.gov (United States)

    Miki, Takahiro; Chairaksa-Fujimoto, Romchat; Maruyama, Katsuya; Nagasaka, Tetsuya

    2016-01-25

    Zinc in Electric Arc Furnace dust or EAF dust mainly exists as ZnFe2O4 and ZnO. While ZnO can be simply dissolved into either an acidic or alkaline solution, it is difficult to dissolve ZnFe2O4. In our previous work, we introduced a process called "CaO treatment", a preliminary pyrometallurgical process designed to transform the ZnFe2O4 in the EAF dust into ZnO and Ca2Fe2O5. The halogens and others heavy metals were favorably vaporized during CaO treatment with no essential evaporation loss of zinc and iron, leaving CaO treated dust which consisted mainly of ZnO and Ca2Fe2O5 and no problematic ZnFe2O4 compound. In this work, the selective leaching of zinc over iron and calcium in the CaO treated dust was investigated using an NH4Cl solution. The effects of temperature, reaction time and NH4Cl concentration on dissolution behavior were examined. While most of the zinc in the CaO treated dust was extracted after 2 h at 70 °C with 2 M NH4Cl, only about 20% of calcium was leached in NH4Cl solution. However, the iron did not dissolve and remained as Ca2Fe2O5 in residue. It was confirmed that zinc can be effectively recovered using NH4Cl solution. PMID:26448494

  11. Effect of CaO doping on mechanical properties and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics

    Institute of Scientific and Technical Information of China (English)

    LAI Yan-qing; ZHANG Yong; ZHANG Gang; TIAN Zhong-liang; LI Jie

    2008-01-01

    The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics were studied. The results show that the samples mainly consist of NiO and NiFe2O4 when content of CaO is less than4%(mass fraction), bending strength increases obviously by CaO doping. Bending strength of the samples doped with 2% CaO is above 185 Mpa, but that of the samples without CaO is only 60 Mpa. Fracture toughness is improved obviously by CaO doping, the undoped ceramics. CaO doping is bad to thermal shock resistance of 10NiO-NiFe2O4 composite ceramics.

  12. Oxidative activation of methane over MgO model catalysts

    OpenAIRE

    Schwach, P.

    2014-01-01

    The role of surface structure and defects in the oxidative coupling of methane (OCM) was studied over magnesium oxide as a model catalyst. Pure MgO nano-particles with varying primary particle size, shape and specific surface area were prepared by sol-gel synthesis, oxidation of metallic magnesium and hydrothermal post treatments. Kinetic studies reveal the occurrence of two parallel reaction mechanisms and a change in the contribution of these pathways to the overall performance of the catal...

  13. Oxidative activation of methane over MgO based catalysts

    OpenAIRE

    Schwach, Pierre

    2015-01-01

    In der vorliegenden Arbeit wurde reines Magnesiumoxid als Modellkatalysator in der oxidativen Kopplung von Methan (OCM) untersucht, wobei Fragen nach dem Einfluss von Defekten und der Oberflächenstruktur auf die katalytischen Eigenschaften im Mittelpunkt standen. Zu diesem Zweck wurde eine Reihe reiner MgO-Katalysatoren unter Anwendung verschiedener Präparationsmethoden, wie Sol-Gel-Synthese, Oxidation von metallischem Magnesium und hydrothermaler Nachbehandlung von MgO, hergestellt. Die Kata...

  14. Phase Transitions of MgO Along the Hugoniot (Invited)

    Science.gov (United States)

    Root, S.; Shulenburger, L.; Lemke, R. W.; Cochrane, K. R.; Mattsson, T. R.

    2013-12-01

    The formation of terrestrial planets and planetary structure has become of great interest because of recent exoplanet discoveries of super earths. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants such as Jupiter, and likely constitutes the interiors of many exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine single crystal MgO under shock compression utilizing experimental and density functional theory (DFT) methods to determine phase transformations along the Hugoniot. We perform plate impact experiments using Sandia's Z - facility on MgO up to 11.6 Mbar. The plate impact experiments generate highly accurate Hugoniot state data. The experimental results show the B1 - B2 solid - solid phase transition occurs near 4 Mbar on the Hugoniot. The solid - liquid transition is determined to be near 7 Mbar with a large region of B2-liquid coexistence. Using DFT methods, we also determine melt along the B1 and B2 solid phase boundaries as well as along the Hugoniot. The combined experimental and DFT results have determined the phase boundaries along the Hugoniot, which can be implemented into new planetary and EOS models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

  15. Sulfation of CaO particles in a carbonation/calcination loop to capture CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Grasa, G.S.; Alonso, M.; Abanades, J.C. [CSIC, Zaragoza (Spain)

    2008-03-15

    CaO is being proposed as a regenerable sorbent of CO{sub 2} via a carbonation/calcination loop. It is well known that natural sorbents lose their capacity to capture CO{sub 2} with the number of cycles due to textural degradation. In coal combustion systems, reaction with the SO{sub 2} present in flue gases also causes sorbent deactivation. This work investigates the effect of partial sorbent sulfation on the amount of CaO used in systems where both carbonation and sulfation reactions are competing. We have found that SO{sub 2} reacts with the deactivated CaO resulting from repetitive calcination/carbonation reactions. Therefore, the deactivation of CaO as a result of the presence of SO{sub 2} is lower than one would expect if one assumes that SO{sub 2} reacts only with active CaO. This work shows that changes in the texture of the sorbent due to repetitive carbonation/calcination cycles tend to increase the sulfation capacity of the sorbents tested. This suggests that the purge of deactivated CaO obtained from a CO{sub 2} capture loop could be a more effective sorbent of SO{sub 2} than fresh CaO.

  16. Grain boundary mobility in anion doped MgO

    Science.gov (United States)

    Kapadia, C. M.; Leipold, M. H.

    1973-01-01

    Certain anions OH(-), F(-) and Gl(-) are shown to enhance grain growth in MgO. The magnitude of their effect decreases in the order in which the anions are listed and depends on their location (solid-solution, second phase) in the MgO lattice. As most anions exhibit relatively high vapor pressures at sintering temperatures, they retard densification and invariably promote residual porosity. The role of anions on grain growth rates was studied in relation to their effect on pore mobility and pore removal; the atomic process controlling the actual rates was determined from observed kinetics in conjunction with the microstructural features. With respect to controlling mechanisms, the effects of all anions are not the same. OH(-) and F(-) control behavior through creation of a defect structure and a grain boundary liquid phase while Cl(-) promotes matter transport within pores by evaporation-condensation. Studies on an additional anion, S to the minus 2nd power gave results which were no different from undoped MgO, possibly because of evaporative losses during hot pressing. Hence, the effect of sulphur is negligible or undetermined.

  17. Nanosilica supported CaO: A regenerable and mechanically hard CO2 sorbent at Ca-looping conditions

    International Nuclear Information System (INIS)

    Highlights: • A synthetic CO2 sorbent is prepared by impregnation of calcium nitrate on a nanosilica matrix. • Sintering of the nascent CaO in the calcination stage of carbonation/calcination cycles is hindered. • CaO conversion reaches a stable value well above the residual conversion of natural limestone. • Particle fragmentation as caused by ultrasonic irradiation in a liquid dispersion is hindered. - Abstract: This work presents a CO2 sorbent that may be synthesized from low-cost and widely available materials following a simple method basically consisting of impregnation of a nanostructured silica support with a saturated solution of calcium nitrate. In a first impregnation stage, the use of a stoichiometric CaO/SiO2 ratio serves to produce a calcium silicate matrix after calcination. This calcium silicate matrix acts as a thermally stable and mechanically hard support for CaO deposited on it by further impregnation. The CaO-impregnated sorbent exhibits a stable CaO conversion at Ca-looping conditions whose value depends on the CaO wt% deposited on the calcium silicate matrix, which can be increased by successive reimpregnations. A 10 wt% CaO impregnated sorbent reaches a stable conversion above 0.6 whereas the stable conversion of a 30 wt% CaO impregnated sorbent is around 0.3, which is much larger than the residual conversion of CaO derived from natural limestone (between 0.07 and 0.08). Moreover, particle size distribution measurements of samples predispersed in a liquid and subjected to high energy ultrasonic waves indicate that the CaO-impregnated sorbent has a relatively high mechanical strength as compared to limestone derived CaO

  18. El caos en los barrios de la frontera en la obra narrativa de L. H. Crosthwaite

    Directory of Open Access Journals (Sweden)

    Mara Donat

    2013-07-01

    Full Text Available If apocalypse is a metaphor of the end and the beginning of an age, collapse of cultural, political and social concepcions, construction of new identities and social realities, literature of “frontera norte de México” is good to realize an investigation of the biblical and mythical theme in postmodern sence. Colapsing any idea of legal and civil life in a national State, urban culture of “la Frontera” presents the social caos of ilegal and criminal conducts, as much es gendre violence and the political idea of national identity in crisis. México protagonize a contradiction between nacionalist pride, frontier defence and emigration to the Unites States, with apocalyptical implication these days. The narrative of Luis Humberto Crosthwaite permit to analyze the different representations of broken identity in the social caos of the frontier. The apocalypsis as inminent catastrophe, social insicurity and uncertain identity leads the individual to new urban and social representations.

  19. Comparison of natural and synthetic precursors of CaO as CO{sub 2} sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Gemma Grasa; Belen Gonzalez; Monica Alonso; J. Carlos Abanades [Dep. Instituto de Carboquimica, CSIC, Zaragoza (Spain). Energy and Environment

    2007-07-01

    Several concepts to capture CO{sub 2} are under developing using CaO as regenerable sorbent. The drastic decay in sorbent capture capacity of CaO obtained from natural sources of CaCO{sub 3} is leading to an increasing number of authors proposing synthetic sorbents to overcome this decay. Some recent developments have been reviewed and tested under comparable conditions. Results confirm the good performance of some of these synthetic sorbents under mild conditions. However, they deactivate also very quickly when realistic regeneration conditions (high calcination temperatures and high concentration of CO{sub 2}) are used in the laboratory test. It is concluded than none of the reviewed synthetic sorbents have a chance to compete with the 'modest' performance of natural limestones that show two competitive advantages: The maintenance of a suitable CO{sub 2} capture capacity under demanding process conditions; and their intrinsic low cost. 21 refs., 5 figs.

  20. Raman and infrared spectroscopy study on structure and microstructure of glass-ceramic materials from SiO2-Al2O3-Na2O-K2O-CaO system modified by variable molar ratio of SiO2/Al2O3

    Science.gov (United States)

    Partyka, Janusz; Leśniak, Magdalena

    2016-01-01

    This paper is focused on the effect of the molar ratio of SiO2/Al2O3 on the microstructure and structure of the internal aluminium-silicon-oxide lattice of the glass-ceramic materials from the SiO2-Al2O3-Na2O-K2O-CaO system. In order to examine the real composition of the obtained samples, a chemical analysis was performed. Following the heat-treatment procedure, pseudowollastonite, anorthite and the vitreous phase were identified. In order to determine the microstructure, research using the scanning electron microscope (SEM) with EDS was done. For the inner structural study, X-ray diffraction (XRD), Raman spectroscopy as well as MIR and FIR spectroscopy were performed.

  1. A Structural Molar Volume Model for Oxide Melts Part II: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 Melts—Ternary and Multicomponent Systems

    Science.gov (United States)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    A structural molar volume model based on the silicate tetrahedral Q-species has been developed to accurately predict the molar volume of molten oxides. In this study, the molar volumes of ternary and multicomponent melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system are reviewed and compared with the predicted molar volumes from the newly developed structural model. The model can accurately predict the molar volumes using binary model parameters without any ternary or multicomponent parameters. The nonlinear behavior in the molar volume of silicate melts is well predicted by the present model.

  2. Materials compatibility during the chlorination of molten CaCl2 . CaO salts

    International Nuclear Information System (INIS)

    As part of our effort to develop a semicontinuous PuO2 reduction process, we are investigating promising materials for containing a 9000C molten CaCl2 . CaO chlorination reaction. We want the material to contain this reaction and to be reusable. We tested candidate materials in a simulated salt (no plutonium) using anhydrous HCl as the chlorinating agent. Data are presented on the performance of 36 metals and alloys, 9 ceramics, and 3 coatings

  3. Teoría del Caos: una visión de su historia y actualidad

    OpenAIRE

    Marco Pedro Ramírez Tachiquín

    2010-01-01

    El empleo de conceptos básicos y ejemplos accesibles, abordar la teoría del caos desde el punto de vista histórico, y algunas de sus aplicaciones modernas, destaca las aportaciones de autores que trabajan en México, y las ramas posibles que podrían ser desarrollados en los próximos años.

  4. Development of CaO coatings by thermal and chemical vapor deposition

    International Nuclear Information System (INIS)

    We have developed CaO coatings that are applied by a thermal and chemical vapor deposition process. Several experiments were conducted to study how the deposition of Ca on a V-4Cr-4Ti substrate alloy is affected by variations in process temperature and time, specimen location, and surface preparation and pretreatment. Results showed that thick adherent coatings can be fabricated by thermal/chemical vapor deposition, especially if a double Ca treatment is applied. Extensive microstructural analysis of the coatings showed almost 100% CaO over a coating thickness of 20-30(micro)m; electrical resistance (measured by the two-probe method) of the coatings was at least two orders of magnitude higher than the minimum required for blanket application. The results obtained in this study indicate that CaO is a viable coating for V-Li advanced blankets, but that significant additional effort is needed, especially from the standpoint of structure/composition relationship to its electrical resistance and the coating stability in a flowing Li environment. Furthermore, resistance must be measured in situ in Li to simultaneously evaluate coating integrity, resistance, and Li compatibility

  5. CERN Technical Training 2002: Learning for the LHC! Introduction à la CAO CADENCE - French version only

    CERN Multimedia

    Davide Vitè

    2002-01-01

    Dans le cadre du suivi du programme ELEC-2002 : Electronics in HEP, une nouvelle session du cours Introduction à la CAO CADENCE. De la saisie de schéma Concept-HDL au PCB est programmée pour le 4 et 5 juin prochains. Le cours, en français, est gratuit et sera animé par Serge Brobecker de la division IT/PS/EAS. Objectif de cette formation est de donner une vue générale du système CAO CADENCE utilisé au CERN, et d'en connaître l'environnement et les possibilités, en acquérant des notions suffisantes pour utiliser la saisie de schéma. Le cours est ciblé pour une audience d'ingénieurs et techniciens désirant utiliser les outils CAO disponibles au CERN, afin de concevoir des circuits logiques et des circuits programmables digitaux. Plus d'information, et possibilité d'inscription par EDH sont accessibles depuis les pages «...

  6. Modified CaO Catalyzed Heterogeneous Synthesis of 3,5-diphenyl-4,5-dihydroisoxazole

    International Nuclear Information System (INIS)

    Dihydroisoxazole derivatives are well known as important nitrogen-containing five-membered heterocyclic compounds with various bioactivity. 3,5-Diphenyl-4,5-dihydroisoxazole was synthesized by using CaO as solid basic catalyst. It was found that 72.1% yield of 3,5-diphenyl-4,5-dihydroisoxazole was obtained at ratio of hydroxylamine/chalcone of 1.2:1 after 3h under reaction temperature of 65 degree C. The reaction efficiency was greatly enhanced with the yield reaching to 88.2% when the CaO was modified by benzyl bromide in a simple way. The effects of modification and reaction conditions on yields as well as the mechanism were studied thoroughly. From the results of Fourier transform-infrared (FT-IR) and Thermogravity analysis (TG) characterization, the modifier was found to bond on CaO surface chemically and almost no Ca(OH)/sub 2/ formed during the modification process. (author)

  7. Intense ${^31-35}$Ar beams produced with a nanostructured CaO target at ISOLDE

    CERN Document Server

    Ramos, J P; Mendonça, T M; Seiffert, C; Senos, A M R; Fynbo, H O U; Tengblad, O; Briz, J A; Lund, M V; Koldste, G T; Carmona-Gallardo, M; Pesudo, V; Stora, T

    2014-01-01

    At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which is connected to an ionizer, from which the charged isotopes are extracted and delivered for physics experiments. Calcium oxide (CaO) powder targets have been used to produce mainly neutron deficient argon and carbon RIBs over the past decades. Such targets presented unstable yields, either decaying over time or low from the beginning of operation. These problems were suspected to come from the degradation of the target microstructure (sintering due to high temperature and/or high proton intensity). In this work, a CaO microstructural study in terms of sintering was conducted on a nanostructured CaO powder synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE i...

  8. Exploration on Cao Cao's Decrees%曹操令体文探析

    Institute of Scientific and Technical Information of China (English)

    刘敏

    2011-01-01

    曹操留下了大量的令体文,其内容丰富,涉及领域广泛,主要有选官任职、褒扬分封、惩戒劝勉、恤亡祭祀、武事战争等内容;形式自由灵活,短小精悍,行文语气也变化多端。无论是内容,还是形式,曹操的令体文都具有开风气之先的历史作用,对当时及后世都产生了深远影响。%Cao Cao has produced many decrees,which are rich in content and extensive in scope,covering selection of officials,assignation of offices,approbation of merits,distribution of land,warning of punishment,remonstration and advice,mourning of the dead,rituals of worship services,military affairs,etc.These decrees are flexible,short,and concise in form,full of variety in its tone.Both in contents and form,Cao Cao's decrees are historically significant for its pioneering role in the history,thus exercising profound influence on his time and later generations.

  9. Initial reaction between CaO and SO2 under carbonating and non-carbonating conditions

    DEFF Research Database (Denmark)

    Rasmussen, Martin Hagsted; Wedel, Stig; Pedersen, Kim H.;

    2015-01-01

    The initial kinetics of the CaO/SO2 reaction have been investigated for reaction times shorter than 1s and in the temperature interval between 450 and 600°C under both carbonating and non-carbonating conditions (0-20 vol% CO2) to clarify how recirculating CaO influences the emission of SO2 from a...... showed that the CaO conversion with respect to SO2 declined when the CO2 concentration was increased. Under all conditions, larger specific surface areas of CaO gave higher reaction rates with SO2. Higher temperatures had a positive effect on the reaction between SO2 and CaO under non...

  10. Decomposition Reaction of Mixed Rare Earth Concentrate and Roasted with CaO and NaCl

    Institute of Scientific and Technical Information of China (English)

    Wu Wenyuan; Hu Guangyong; Sun Shuchen; Chen Xudong; Tu Ganfeng

    2004-01-01

    The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ~ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.

  11. Homegardens of the Cao Lan, a Tai-Speaking Ethnic Minority in Vietnam’s Northern Mountains

    OpenAIRE

    Pijika Timsuksai; Nguyen Dinh Tien; A. Terry Rambo

    2015-01-01

    The Cao Lan are a Tai-speaking ethnic group living in the Midlands of Northern Vietnam. Homegardens are an important component of their agroecosystem. The ecological structures of each homegarden of 17 households of the Cao Ngoi village in Tuyen Quang province were described and modal patterns identified. Most homegardens have organically shaped planting areas with indeterminate boundaries, polycentric planting patterns, and contain multiple species within the same bed or planting area. All o...

  12. Design and manufacture of X-ray analyser of CaO, Fe2O3, SiO2 and Al2O3, investment opportunity of Vietnam cement factories

    International Nuclear Information System (INIS)

    Cement is produced by heating naturally occurring raw materials containing the required oxides in kiln, which results in a product called clinker. To obtain the finished cement, the clinker is then ground together with gypsum, which controls setting properties, to a fine powder. Portland cement is a mixture of compounds formed from the oxides of Ca(CaO), Si(SiO2), Al(Al2O3), and Fe(Fe2O3). In addition to these four main constituents it also contains smaller amounts of MgO, K2O, SO3, etc. Effective process control of cement is important to ensure high quality of the product. Traditionally wavelength dispersive x-ray fluorescence (WDXRF) spectrometers are used for cement quality control at the modern cement factories. The XRF-NCS02 is a compact energy dispersive X-ray fluorescence (EDXRF) analyzer. These spectrometers also are used for cement quality control at the small size cement plant. Product description: The XRF-NCS02 , table-top cement analyzer is a computer-based EDXRF spectrometer. The high efficiency and high resolution Si PIN detector is coupled to a 4096 channel MCA for data collection. The special low-power x-ray tube of the system requires no cooling and obligates the need for radioisotopes, as commonly found on such instruments. Computer: Compatible notebook or desktop PC, Pentium processor with CD-ROM. Software: XRF - NCS02 software for quantitative analysis; Interactive, operation under Windows XP. Installation: dimensions 500x380x300 mm (W x D x H); weight: 10 kg. (author)

  13. Synthesis of MgO Nanoparticles by Solvent Mixed Spray Pyrolysis Technique for Optical Investigation

    OpenAIRE

    Nemade, K. R.; S. A. Waghuley

    2014-01-01

    Solvent mixed spray pyrolysis technique has attracted a global interest in the synthesis of nanomaterials since reactions can be run in liquid state without further heating. Magnesium oxide (MgO) is a category of the practical semiconductor metal oxides, which is extensively used as catalyst and optical material. In the present study, MgO nanoparticles were successfully synthesized using a solvent mixed spray pyrolysis. The X-ray diffraction pattern confirmed the formation of MgO phase with a...

  14. A novel approach for arsenic adsorbents regeneration using MgO

    OpenAIRE

    Tresintsi, Sofia; Simeonidis, Konstantinos; Katsikini, Maria; Paloura, Eleni; Bantsis, Georgios; Mitrakas, Manassis

    2014-01-01

    An integrated procedure for the regeneration of iron oxy-hydroxide arsenic adsorbents by granulated MgO is proposed in this study. A continuous recirculation configuration, with a NaOH solution flowing sequentially through the saturated adsorbent (leaching step) and the MgO (adsorption step) column beds, was optimized by utilizing the high arsenic adsorption efficiency of MgO at strong alkaline environments. Experimental results indicated that the total amount of leached arsenic was captured ...

  15. Growth and morphology of the epitaxial Fe(110)/MgO(111)/Fe(110) Trilayers

    OpenAIRE

    Fonin, Mikhail; Dedkov, Yuriy S.; Rüdiger, Ulrich; Güntherodt, Gernot

    2007-01-01

    Growth and surface morphology of epitaxial Fe(110)/MgO(111)/Fe(110) trilayers constituting a magnetic tunnel junction were investigated by low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). STM reveals a grain-like growth mode of MgO on Fe(110) resulting in dense MgO(111) films at room temperature as well as at 250°C. As observed by STM, initial deposition of MgO leads to a partial oxidation of the Fe(110) surface which is confirmed by Auger electron spectroscopy....

  16. Autocatalytic surface hydroxylation of MgO(100) terrace sites observed under ambient conditions

    DEFF Research Database (Denmark)

    Newberg, J.T.; Mysak, E.R.; Bluhm, H.; Porsgaard, Søren; Salmeron, M.B.; Starr, D.E.; Yamamoto, S.; Kaya, S.; Brown, G.E.; Nilsson, A.; Kendelewicz, T.

    2011-01-01

    We have investigated the reaction of water vapor with the MgO(100) surface using ambient pressure X-ray photoelectron spectroscopy (AP-XPS), which permits the study of the chemical composition of the MgO/water vapor interface at p(H2O) in the Torr range. Water dissociation on thin MgO(100) films of...... interacting with a fully hydroxylated interface on MgO(100). The observed onset of hydroxylation near 0.01% RH is suggested to be due to water molecules aggregating at the surface, leading to an autocatalytic dissociation of water at MgO(100) terrace sites....

  17. Measurement of Townsend's Secondary Ionization Coefficient of MgO Film in Argon

    Science.gov (United States)

    Suzuki, Susumu; Konno, Kazuya; Itoh, Haruo

    Townsend's secondary ionization coefficients γ of MgO in Ar are determined from the breakdown voltages and the Townsend's criterion. Breakdown voltages on MgO film are measured by the both wave forms, discharge current and applied voltage between the electrodes on the oscilloscope. According to the experimental procedure, γ of gold film and stainless steel electrodes are determined and compared with other experimental values. After the confirmation of the validity of those results, we have carried out the determination for γ of MgO. Furthermore, the influence of heating effect of MgO film to the value of γ is also discussed.

  18. Intrinsic spin noise in MgO magnetic tunnel junctions

    OpenAIRE

    Delgado Acosta, Fernando; K. Lopez; Ferreira, R.; Fernández Rossier, Joaquín

    2012-01-01

    We consider two intrinsic sources of noise in ultra-sensitive magnetic field sensors based on MgO magnetic tunnel junctions, coming both from $^{25}$Mg nuclear spins ($I=5/2$, 10% natural abundance), and S=1 Mg-vacancies. While nuclear spins induce noise peaked in the MHz frequency range, the vacancies noise peaks in the GHz range. We find that the nuclear noise in submicron devices has a similar magnitude than the $1/f$ noise, while the vacancy-induced noise dominates in the GHz range. Inter...

  19. Adsorption of Ar on a nonuniform MgO surface

    Science.gov (United States)

    Hinman, D. C.; Halsey, G. D.

    1976-01-01

    Data are presented for the adsorption of Ar and N2 on a strongly heterogeneous MgO surface at 84 K and for Ar at a range of temperatures between 130 and 250 K. The high-temperature data are analyzed according to a model which separates the contributions to the potential into bulk and surface terms, providing a method for the determination of the surface area from parameters characteristic of the bulk material. A solid-gas energy parameter and parameters indicating the strength of the impurity sites are also evaluated.

  20. Screening of MgO- and CeO2-Based Catalysts for Carbon Dioxide Oxidative Coupling of Methane to C2+ Hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    Istadi; Nor Aishah Saidina Amin

    2004-01-01

    The catalyst screening tests for carbon dioxide oxidative coupling of methane (CO2-OCM)have been investigated over ternary and binary metal oxide catalysts. The catalysts are prepared by doping MgO- and CeO2-based solids with oxides from alkali (Li2O), alkaline earth (CaO), and transition metal groups (WO3 or MnO). The presence of the peroxide (O22-) active sites on the Li2O2, revealed by Raman spectroscopy, may be the key factor in the enhanced performance of some of the Li2O/MgO catalysts.The high reducibility of the CeO2 catalyst, an important factor in the CO2-OCM catalyst activity, may be enhanced by the presence of manganese oxide species. The manganese oxide species increases oxygen mobility and oxygen vacancies in the CeO2 catalyst. Raman and Fourier Transform Infra Red (FT-IR) spectroscopies revealed the presence of lattice vibrations of metal-oxygen bondings and active sites in which the peaks corresponding to the bulk crystalline structures of Li2O, CaO, WO3 and MnO are detected. The performance of 5%MnO/15%CaO/CeO2 catalyst is the most potential among the CeO2-based catalysts,although lower than the 2%Li2O/MgO catalyst. The 2%Li2O/MgO catalyst showed the most promising C2+ hydrocarbons selectivity and yield at 98.0% and 5.7%, respectively.

  1. Melting Phase Relations and "Stishovite Paradox" in Lower-Mantle System MgO - FeO - SiO2 at 24 GPa

    Science.gov (United States)

    Litvin, Yuriy; Spivak, Anna; Dubrovinsky, Leonid

    2014-05-01

    Stishovite is missed in model composition of the ultrabasic lower mantle (Akaogi, 2007; Stixrude, Lithgow-Bertelloni, 2007). It is due to the fact that mineralogy of the lower mantle is estimated by experimental study of phase relation of the pyrolite composition up to 50 GPa. It was found that ultrabasic assemblage magnesiowustite+Mg-perovskite+Ca-perovskite is stable at PT-conditions of the lower mantle. However, stishovite is a representative phase in basic assemblage stishovite+Ca-perovskite+Mg-perovskite+Al-bearing resulted in similar experiments with basaltic compositions. But in this case stishovite should be subducted into the lower mantle. Meanwhile, paradoxal intergrowths of stishovite with magnesiowustite, indicatory mineral of the ultrabasic lower mantle, were found out as inclusions in 'super-deep' diamonds (Kaminsky, 2011, for review). Physicochemical reasons for in situ formation of stishovite and assemblage of stishovite and magnesiowustite ('stishovite paradox') at the primitive lower mantle were earlier discussed (Litvin et al, 2014). The discussion was based on preliminary data for melting phase relations of the lower mantle system MgO - FeO - SiO2 - Ca-perovskite. The goal of this work is experimental investigation of phase relations on the ternary MgO - FeO - SiO2 join of the lower mantle system MgO - FeO - SiO2 - CaO at pressure of 24 GPa. The sections (MgO)70(FeO)30-(SiO2)70(FeO)30 and (MgO)30(FeO)70-(SiO2)30(FeO)70of the ternary join were studied and melting phase diagrams for them constructed. Melting relations of the MgO - FeO - SiO2 join are characterized by formation of invariant peritectic point (Mg,Fe)-perovskite+(Mg,Fe)O+stishovite+L(liquid) and monovariant cotectic curve (Mg,Fe)O+stishovite+ L at compositions richer in FeO. Thus, peritectic reaction of (Mg,Fe)-perovskite and Fe-richer liquid is responsible for magnesiowustite (Mg,Fe)O + stishovite SiO2paragenesis. Origin of model primary ultrabasic magma is under control of

  2. Solubility of MgO in chloride melts containing NdCl3 or LaCl3

    OpenAIRE

    Li, Bing; Li, Jun; Chen, Jinzhong; Yu, Jianguo

    2009-01-01

    Due to extremely low solubility in conventional magnesium electrolyte, MgO tends to attach to cathode and causes cathodic passivation, which will dramatically lower current efficiency of magnesium electrolysis. In this paper, NdCl3 or LaCl3 was added to conventional magnesium electrolyte to increase MgO solubility. We investigated the effects of NdCl3 or LaCl3 content, the form of MgO, and temperature on the dissolution rate of MgO and on MgO solubility. MgO solubility increased with increasi...

  3. High photoelectron emission from Co-diffused MgO deposited using arc plasma gun

    Science.gov (United States)

    Yamamoto, Shin-ichi; Kosuga, Hiroki

    2015-08-01

    MgO has several advantageous characteristics and has been applied in various fields. In this study, we deposited Co nanoparticles in an island pattern on a Si substrate using an arc plasma gun (APG). We subsequently formed a MgO thin film on this substrate by metal-organic decomposition (MOD), which enables the formation of films in the atmosphere, thereby yielding a double-layer structure. The MgO thin film formed on Co nanoparticles deposited using the APG with 500 pulses of arc discharge exhibited improved crystallinity and photoelectron emission at least threefold higher than that of a MgO thin film formed directly without depositing Co nanoparticles. Although the transmittance of the specimen formed by depositing Co nanoparticles was initially 30% or lower, it increased to greater than 90% after the formation of the MgO thin film and the dispersion of the Co nanoparticles in the MgO thin film during heat treatment at 900 °C. Our results clarify that the characteristics of MgO thin films are markedly improved by depositing Co nanoparticles before forming the films. The results of Kelvin probe force microscopy (KPFM) indicate that the outermost surface of the Co material had become CoO (cobalt oxide) with the dispersion of Co nanoparticles in the MgO thin film. The lattice parameter of CoO nanoparticles (an-axis lattice parameter of 4.2615 Å) after heating matches well with that of MgO (4.2126 Å). The MgO thin films that grew in conjunction with the CoO nanoparticles were highly crystallized. We successfully established a high-performance, cost-effective bottom-up process that requires no ion injection by dispersing Co nanoparticles in a MgO thin film through heat treatment.

  4. Nanoindentation, microindentation and cathodoluminescence of MgO crystals

    International Nuclear Information System (INIS)

    Micro and nano indentations were applied together with scanning electron microscopy (SEM), atomic force microscopy (AFM), cathodoluminescence (CL), cathodoluminescence spectroscopy (CLS) and computer graphics to obtain subsidiary information about peculiarities and regularities of plastic deformation in MgO. The movement of displaced material, production of dislocation structures, luminescent centres as well as the development of various slip traces and formation of cracks are discussed. Local CL spectrums were recorded and some peaks in the short wavelength part of the composite CL band were found and examined in an attempt to sort out the various defect contributions. The most intensive peak observed at λ=370 nm was attributed to oxygen-vacancy defects F+ centres, which have trapped one electron. The band in at λ=470 nm was identified as F2+ centres (i.e. aggregates of two anion vacancies that have trapped three electrons). Images at these wavelengths were displayed and the spatial distribution of the CL intensity correlates with concentration of selected oxygen-vacancy defects. It was demonstrated that a combination of different techniques allows a better understanding of the mechanical response and interpretation of defect behaviour around residual indentations in MgO single crystals when subjected to impose stresses. (authors)

  5. Viability of Clostridium sporogenes spores after CaO hygienization of meat waste

    Directory of Open Access Journals (Sweden)

    Justyna Bauza-Kaszewska

    2014-09-01

    Full Text Available The occurrence of the pathogenic species [i]C. perfringens[/i] and [i]C. botulinum spores[/i] in animal by-products poses a potential epidemiological hazard. Strong entero- and neurotoxins produced by these bacteria adversely affect human health. To inactivate pathogens present in animal by-products, waste must be subjected to various methods of sanitization. The aim of the presented study was to estimate the effect of different doses of CaO on the viability of spores [i] Clostridium sporogenes[/i] in meat wastes category 3. During the research, two doses of burnt lime were added to the poultry mince meat and meat mixed with swine blood contaminated with [i]Clostridium sporogenes[/i] spore suspension. Half of the samples collected for microbiological analyses were buffered to achieve the pH level ~7, the other were examined without pH neutralization. To estimate the spore number, 10-fold dilution series in peptone water was prepared and heat-treated at 80 °C for 10 min. After cooling-down, one milliliter of each dilution was pour-plated onto DRCM medium solidified with agar. Statistical analysis were performed using the Statistica software. Application of 70% CaO caused complete inactivation of [i]Clostridium spores[/i] in meat wastes after 48 hours. The highest temperature achieved during the experiment was 67 °C. Rapid alkalization of the biomass resulted in increasing pH to values exceeding 12. The effect of liming was not dependent on the meat wastes composition nor CaO dose. The experiment proved the efficiency of liming as a method of animal by-products sanitization. Application of the obtained results may help reduce the epidemiological risk and ensure safety to people handling meat wastes at each stage of their processing and utilization.

  6. A new fluidized bed combustion system to capture CO{sub 2} with CaO

    Energy Technology Data Exchange (ETDEWEB)

    J. Carlos Abanades; Diego Alvarez; Gemma Grasa; Enric Soley; Jesus Pajares [Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

    2005-07-01

    A combustion system that includes CO{sub 2} capture, and comprises three interconnected fluidized beds, is described. Coal is first burned in a circulating fluidised bed combustor at temperatures around 1000{sup o}C in the presence of a large flow of CaO, that is acting here as a heat carrier. After heat recovery, these gases enter a second circulating fluidized bed operating at around 650{sup o}C where they meet again CaO particles, capturing the CO{sub 2} in the flue gas as CaCO{sub 3}. The CaCO{sub 3} particles are separated from the gas and sent to a calciner fluidized by steam and CO{sub 2}. The heat required for calcination is supplied by the particles of CaO circulating from the high temperature combustor. Since the separation of CO{sub 2} is carried out at high temperatures, there are negligible efficiency penalties. In this work we focus on the effect of sorbent performance on the operating variables expected in the different units. Multicycle carbonation-calcination-combustion tests have been carried out with natural limestones at conditions representative of their life in the circulating system. The decay in sorbent capacity has been measured up to 500 cycles. The consequences of the rapid decay, but also the stability found in long cycle numbers (between 5-10% Ca conversion) are discussed in terms of the solid flow requirements to achieve a given CO{sub 2} separation efficiency. It is shown that this is a promising system where only relatively modest make up flows of limestone are required to maintain the activity in the CO{sub 2} capture loop and to purge the system of inert components. 22 refs., 6 figs., 2 tab.

  7. Evaluation of CO2 carrying capacity of reactivated CaO by hydration

    OpenAIRE

    Martínez, I; Grasa, Gemma S.; Murillo, R.; Arias Rozada, Borja; Abanades García, Juan Carlos

    2011-01-01

    [EN] Steam hydration has been proposed as a suitable technique for improving the performance of CaO as a regenerable sorbent in CO2 capture systems. New hydration experiments conducted in this study, confirm the reported improvements in the capacity of sorbents to carry CO2. An examination of the textural properties of the sorbent after hydration and mild calcination revealed a large increase in the area of reaction surface and the formation of a fraction of pores ≈20 nm diameter that enhance...

  8. Codeboek DUCADAM dataset: een statistisch bestand van de FNV cao-databank

    OpenAIRE

    Schreuder, K.; Tijdens, K.

    2004-01-01

    The ‘FNV cao-databank’ is a digital database that stores all collective labour agreements negotiated by FNV trade unions in the Netherlands since 1995. Every agreement has been coded with respect to 650 different characteristics. The DUCADAM dataset is both a scientific translation of this database and an extension of it. The extension consists of newly created meta-variables, which are not actually included in CLAs but are closely tied to them. In the DUCADAM dataset codebook, the complete d...

  9. Viability of Clostridium sporogenes spores after CaO hygienization of meat waste

    OpenAIRE

    Justyna Bauza-Kaszewska; Zbigniew Paluszak; Krzysztof Skowron

    2014-01-01

    The occurrence of the pathogenic species [i]C. perfringens[/i] and [i]C. botulinum spores[/i] in animal by-products poses a potential epidemiological hazard. Strong entero- and neurotoxins produced by these bacteria adversely affect human health. To inactivate pathogens present in animal by-products, waste must be subjected to various methods of sanitization. The aim of the presented study was to estimate the effect of different doses of CaO on the viability of spores [i] Clostridium sporogen...

  10. Importancia del caos determinista en medicina Importance of deterministic chaos in medicine

    OpenAIRE

    Luis Carlos Burgos Herrera

    1994-01-01

    La impredecibilidad de los sistemas, incluso de los regidos por leyes deterministas, cuando despliegan su evolución se llama caos determinista. En este artículo se revisan algunos aspectos históricos de tal concepto; se describen sus características y los métodos empleados para su estudio. Se mencionan las ventajas que ofrece el comportamiento caótico para los sistemas fisiológicos normales, contrastando el conc...

  11. Pulsed injection metal organic chemical vapour deposition and characterisation of thin CaO films

    International Nuclear Information System (INIS)

    Thin films of CaO were grown on silicon (Si) and lanthanum aluminate (LaAlO3) substrates by pulsed injection metal-organic chemical vapour deposition in a vertical injection MOCVD system. Growth parameters were systematically varied to study their effect on film growth and quality and to determine the optimal growth conditions for this material. Film quality and growth rate were evaluated by atomic force microscopy, X-ray diffraction and Rutherford Backscattering Spectroscopy measurements. Optimised conditions allowed growing transparent, single phase films textured along the (0 0 l) direction.

  12. Teoría del caos, cognitivismo y semántica

    OpenAIRE

    Lic. Raymond Colle

    1998-01-01

    El origen del pensamiento no tiene nada de secuencial: el cerebro es un "mecanismo" que opera con una altísima tasa de paralelismo. Es también un sistema altamente complejo y comparte algunas características de funcionamiento de todos los sistemas altamente complejos. En este artículo se citan a diversos investigadores que han puesto en evidencia los fenómenos de aparición del orden en medio del "caos" en sistemas complejos; se explica cómo el pensamiento se ordena en torno a "atractores", fo...

  13. Intense {sup 31–35}Ar beams produced with a nanostructured CaO target at ISOLDE

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.P. [CERN, CH-1211 Genève 23 (Switzerland); Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Gottberg, A. [CERN, CH-1211 Genève 23 (Switzerland); Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain); Mendonça, T.M. [CERN, CH-1211 Genève 23 (Switzerland); IFIMUP-IN, Institute of Nanosciences and Nanotechnology, University of Porto, 4169-007 Porto (Portugal); Seiffert, C. [CERN, CH-1211 Genève 23 (Switzerland); Technische Universität Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Senos, A.M.R. [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Fynbo, H.O.U. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Åarhus (Denmark); Tengblad, O.; Briz, J.A. [Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain); Lund, M.V.; Koldste, G.T. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Åarhus (Denmark); Carmona-Gallardo, M.; Pesudo, V. [Instituto de Estructura de la Materia, CSIC, Serrano 113 bis, E-28006 Madrid (Spain); Stora, T., E-mail: thierry.stora@cern.ch [CERN, CH-1211 Genève 23 (Switzerland)

    2014-02-01

    Highlights: • A nanometric mesoporous CaO powder was developed and studied in terms of sintering. • For the first time a nanostructured target material was operated at ISOLDE. • Unlike past CaO targets, stable yields over time of n-deficient argon were delivered. • Higher (exotic) Ar yields were obtained at lower temperatures and proton intensities. -- Abstract: At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which is connected to an ionizer, from which the charged isotopes are extracted and delivered for physics experiments. Calcium oxide (CaO) powder targets have been used to produce mainly neutron deficient argon and carbon RIBs over the past decades. Such targets presented unstable yields, either decaying over time or low from the beginning of operation. These problems were suspected to come from the degradation of the target microstructure (sintering due to high temperature and/or high proton intensity). In this work, a CaO microstructural study in terms of sintering was conducted on a nanostructured CaO powder synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE in terms of the CaO target production, handling and operation in order to produce and maintain the nanostructured CaO. The new target, the first nanostructured target to be operated at ISOLDE, showed improved yields of (exotic) Ar and more importantly a stable yield over the whole operation time, while operating with lower temperatures. This contradicts the ISOL paradigm of using the highest possible temperature regardless of the target’s microstructure degradation.

  14. Incorporating IGCC and CaO sorption-enhanced process for power generation with CO2 capture

    International Nuclear Information System (INIS)

    Highlights: ► CaO sorption-enhanced process is incorporated with IGCC for CO2 capture. ► IGCC–CCS is simplified using CaO sorption-enhanced process. ► The electricity efficiency is around 31–33% and CO2 capture efficiency exceeds 95%. ► Parameters such as sorption pressure influence the system performance. -- Abstract: Integrated gasification combined cycle (IGCC) is a power generation technology to convert solid fuels into electricity. IGCC with CCS is regarded as a promising option to mitigate CO2 emission. In this paper, the CaO sorption-enhanced process is incorporated downstream with coal gasification to produce a hydrogen-rich stream for electricity production and CO2 separation. A WGS-absorber substitutes the high- and low-temperature water–gas shift reactors and desulfurization units in conventional IGCC–CCS to produce a hydrogen-rich stream, which is sent onto a gas turbine. CaO is used as the sorbent to enhance hydrogen production and for CO2 capture. Regeneration of CaO is completed via calcination in a regenerator vessel. The IGCC with CaO sorption-enhanced process is modeled and simulated using Aspen Plus software. Two commercial available gasification technologies, Shell and Texaco, are integrated with the sorption-enhanced process. The results showed IGCC with CaO sorption-enhanced process has a satisfactory system performance. Even though the net electricity efficiency is not as high as expected, just around 30–33%, the system has a high CO2 capture efficiency ∼97% and low pollutant emissions. Moreover, compared with conventional IGCC–CCS, the schematic diagram of the IGCC–CCS process is simplified. Parameters that affect the plant performance are analyzed in the sensitive analysis, including WGS-absorber temperature, H2O/CO ratio, pressure, etc. Some challenges to the system are also discussed.

  15. Technical Report on the Impact of MgO on Defense Waste Processing Facility

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the effect(s) of removing MgO from DWPF frits to assess the impact on liquidus temperature and the durability of the glass product. Removal of MgO from the frit was hypothesized to lead to a decrease in liquidus temperature and thereby allow increased waste loading

  16. Low cost porous MgO substrates for oxygen transport membranes

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Søgaard, Martin; Clemens, F.; Sudireddy, Bhaskar Reddy; Kaiser, Andreas

    2016-01-01

    This paper delineates the fabrication of porous magnesium oxide (MgO) ceramics with high porosity and gas permeability by warm pressing using pre-calcined MgO powder and fugitive pore former (combination of graphite and polymethyl methacrylate). Effect of pore former on the microstructure develop...

  17. Influence of oxygen content on the crystallinity of MgO layers in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    With RF sputtering process, Si/SiO2/Ta/Ru/Ta/CoFeB/MgO/CoFeB/Ta/Ru structure has been grown on Si (100) substrate. Attempting different targets and adjusting the oxygen dose, the crystallization quality of the MgO layer is studied. The X-ray diffraction measurements demonstrate that crystal structure and crystallization quality of MgO layers are related to the type of target and concentration of oxygen in sputtering process. With the method sputtering Mg in an ambient flow of oxygen, not only the crystallization quality of a normal MgO layer with lattice constant of 0.421 nm is improved, but also a new MgO crystal with lattice constant of 0.812 nm is formed and the perpendicular magnetic anisotropy of CoFeB is enhanced. Also it is found that crystallization quality for both the normal MgO and new MgO is more improved with MgO target and same oxygen dose, which means that this new method is helpful to form a new structure of MgO with lattice constant of 0.812 nm. All of the samples were annealed at 400 °C in vacuum. (semiconductor materials)

  18. Low-pressure ETEM Studies of Au assisted MgO Nanorod Growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    2014-01-01

    Environmental transmission electron microscopy (ETEM) studies MgO nanorod growth from Au catalyst nanoparticles in a controlled gas atmosphere have been performed, in order to elucidate the mobility of Au surface atoms and the configuration of the Au/MgO interface. MgO nanorod growth is driven by...

  19. The conduction bands of MgO, MgS and HfO2

    NARCIS (Netherlands)

    Boer, P.K. de; Groot, R.A. de

    1998-01-01

    Electronic structure calculations for MgO, MgS and HfO2 are reported. It is shown that the conduction bands of MgO and MgS have predominantly anion character, contrary to the common picture of the conduction band being derived from cation states. In transition metal oxides, unoccupied anion states a

  20. Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

    Science.gov (United States)

    The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against E. coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achievin...

  1. Effective modification of MgO with surface transition metal oxides for NF3 decomposition

    Institute of Scientific and Technical Information of China (English)

    Yanan Wang; Xiufeng Xu; Pei Sheng; Hongguang Li; Tingting Wang; Youfen Huang; Fangshu Liu

    2011-01-01

    NF3 decomposition over transition metal oxides coated MgO reagents in the absence of water is investigated.The results show that NF3 can be decomposed completely over pure MgO but the time of NF3 steady full conversion kept as short as 80 min,while the reactivities of coated MgO reagents were remarkably enhanced by transition metal oxides,for example the time of NF3 complete conversion over 12%Fe/MgO extended to 380 min.It is suggested that not only an increase in surface area but also a significant enhancement in the fluorination of MgO substrate caused by the surface transition metal oxides result in an improved reactivity of coated MgO reagents for NF3 decomposition.

  2. Preparation of photoluminescent single crystalline MgO nanobelts by DC arc plasma jet CVD

    International Nuclear Information System (INIS)

    Magnesium oxide (MgO) nanostructures were synthesized by DC arc plasma jet chemical vapor deposition, which possesses the advantages of being simple, economical, fast, effective and environmentally benign. The formation of “tadpole”-, dendrite-, belt- and rod-like MgO nanostructures was confirmed by scanning electron microscopy and high-resolution transmission electron microscopy. Powder X-ray diffraction analysis revealed that the nanostructures consist of cubic phase MgO. Nanobelts that were 30–50 nm wide with a width/thickness ratio of 1–2 were synthesized in just 5 min. Most of the nanobelts were connected to others, and the connected nanobelts possessed a single-crystal structure. A formation mechanism for MgO nanostructures was proposed. Fourier transform infrared spectra indicated the adsorption of water and CO2 on the MgO surface. The nanobelts exhibited relatively strong blue-green luminescence

  3. Molecular dynamics study for the melting curve of MgO at high pressure

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Zhang Hong; Cai Ling-Cang

    2004-01-01

    Shell-model molecular dynamics method is used to study the melting temperatures of MgO at elevated temperatures and high pressures using interaction potentials. Equations of state for MgO simulated by molecular dynamics are in good agreement with available experimental data. The pressure dependence of the melting curve of MgO has been calculated. The surface melting and superheating are considered in the correction of experimental data and the calculated values, respectively. The results of corrections are compared with those of previous work. The corrected melting temperature of MgO is consistent with corrected experimental measurements. The melting temperature of MgO up to 140GPa is calculated.

  4. Evaporation mechanisms of MgO in laser assisted atom probe tomography

    KAUST Repository

    Mazumder, Baishakhi

    2011-05-01

    In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

  5. Epitaxial growth of tungsten layers on MgO(001)

    International Nuclear Information System (INIS)

    Smooth single crystal W(001) layers were grown on MgO(001) substrates by magnetron sputtering at 900 °C. X-ray diffraction ω–2θ scans, ω-rocking curves, pole figures, and reciprocal space maps indicate a 45°-rotated epitaxial relationship: (001)W‖(001)MgO and [010]W‖[110]MgO, and a relaxed lattice constant of 3.167 ± 0.001 nm. A residual in-plane biaxial compressive strain is primarily attributed to differential thermal contraction after growth and decreases from −0.012 ± 0.001 to −0.001 ± 0.001 with increasing layer thickness d = 4.8–390 nm, suggesting relaxation during cooling by misfit dislocation growth through threading dislocation glide. The in-plane x-ray coherence length increases from 3.4 to 33.6 nm for d = 4.8–390 nm, while the out-of-plane x-ray coherence length is identical to the layer thickness for d ≤ 20 nm, but is smaller than d for d ≥ 49.7 nm, indicating local strain variations along the film growth direction. X-ray reflectivity analyses indicate that the root-mean-square surface roughness increases from 0.50 ± 0.05 to 0.95 ± 0.05 nm for d = 4.8–19.9 nm, suggesting a roughness exponent of 0.38, but remains relatively constant for d > 20 nm with a roughness of 1.00 ± 0.05 nm at d = 47.9 nm

  6. Importancia del caos determinista en medicina Importance of deterministic chaos in medicine

    Directory of Open Access Journals (Sweden)

    Luis Carlos Burgos Herrera

    1994-02-01

    Full Text Available

    La impredecibilidad de los sistemas, incluso de los regidos por leyes deterministas, cuando despliegan su evolución se llama caos determinista. En este artículo se revisan algunos aspectos históricos de tal concepto; se describen sus características y los métodos empleados para su estudio. Se mencionan las ventajas que ofrece el comportamiento caótico para los sistemas fisiológicos normales, contrastando el concepto de irregularidad caótica con el de homeostasia y se mencionan las implicaciones más importantes que tiene el descubrimiento de la ubicuidad del caos sobre las definiciones de salud y enfermedad.

    The unpredictability of systems, including those ruled by deterministic laws, is known as deterministic chaos. In this article some historical aspects, characteristics and methods of study of this concept are briefly described. The advantages of chaotic rhythm for physiological systems are summarized and the implications of ubicuity of chaos in human physiology for the definitions of hea1th and disease are reviewed.

  7. The Experiences of e-Learning Implementation in CAO - Results of the Pilot Project

    Directory of Open Access Journals (Sweden)

    Zsuzsanna Vörös

    2010-12-01

    Full Text Available The various tasks of Central Agricultural Office are carried out by its central and regional directorates. For performing a high standard labour, well- and continuously educated team in needed, so the more thousands of colleagues working at central and regional levels have to be trained. Beside the traditional training forms – and built to them - there was a need for implementing a new distant teaching system, which provides a comprehensive distance education, resting on multimedia foundations, for the all colleagues of Central Agricultural Office working in different parts of the country and in different professional areas. The aim of our publication is to show how we introduced the e-Learning education within the distance education framework system of CAO, and to share our experiences obtained during the pilot training. The five courses of pilot training turned out a success: the results of examinations (the mean values: 84-91% and evaluations of questionnaires filled out by more than 200 colleagues taking part in training proved the entitlement of e-Learning education in CAO. However this method needs additional refinements in order to adapt to the specific requirements of andrology.

  8. Relationship between alkaloid contents and growth environment of Yimu Cao (Herba Leonuri)

    Institute of Scientific and Technical Information of China (English)

    CHAO Zhi; YAN Gang

    2001-01-01

    To study the relationship between alkaloids contents in Chinese traditional drug Yimu Cao (the dried aerial parts ofLeonurus artemisia) and its growing environment. Methods: Samples of the drug and the soil at the growing site collected from 5 selected regions. Reference materials were checked and on-the-spot observations were carried out to investigate the growth environment. RP-HPLC was performed to determine the alkaloid contents in the drug. Results: Different regions had different environmental conditions, including climate, soil, vegetation, and so on.No matter barren or fertile the soil at the growing site was, the herb ofL. Artemisia could grow well, but the contents of alkaloid in the drug varied greatly. The drugs produced in 2 northern regions, where the soil is alkaline, had higher content of alkaloid (about 0.4%) than that produced in southern regions (0.1%-0.2%), where the soil is acid. Conclusion:The contents of organic matters, effective phosphorus, quick-acting potassium, and the pH value of the growing site soil were the factors correlating with alkaloid contents in the drug, among which the pH value of soil was an important positively correlating factor. The alkaline soils in North benefit the accumulation of alkaloids more than the acid soils in South. The other probable elements affecting the alkaloid contents in Yimu Cao were climate and genetic factors.

  9. Preparation of novel ceramics with high CaO content from steel slag

    International Nuclear Information System (INIS)

    Highlights: • Efficiently utilize such solid waste with high CaO content. • A novel ceramics was put forward by traditional ceramic process. • The novel ceramics attained high strength. • Sintering mechanisms of the novel ceramics were discussed. - Abstract: Steel slag, an industrial waste discharged from steelmaking process, cannot be extensively used in traditional aluminosilicate based ceramics manufacturing for its high content of calcium oxide. In order to efficiently utilize such solid waste, a method of preparing ceramics with high CaO content was put forward. In this paper, steel slag in combination with quartz, talcum, clay and feldspar was converted to a novel ceramic by traditional ceramic process. The sintering mechanism, microstructure and performances were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) techniques, combined experimenting of linear shrinkage, water absorption and flexural strength. The results revealed that all crystal phases in the novel ceramic were pyroxene group minerals, including diopsite ferrian, augite and diopsite. Almost all raw materials including quartz joined the reaction and transformed into pyroxene or glass phase in the sintering process, and different kinds of clays and feldspars had no impact on the final crystal phases. Flexural strength of the ceramic containing 40 wt.% steel slag in raw materials can reach 143 MPa at sintering temperature of 1210 °C and its corresponding water absorption, weight loss, linear shrinkage were 0.02%, 8.8%, 6.0% respectively. Pyroxene group minerals in ceramics would contribute to the excellent physical and mechanical properties

  10. A Structural Molar Volume Model for Oxide Melts Part I: Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 Melts—Binary Systems

    Science.gov (United States)

    Thibodeau, Eric; Gheribi, Aimen E.; Jung, In-Ho

    2016-04-01

    A structural molar volume model was developed to accurately reproduce the molar volume of molten oxides. As the non-linearity of molar volume is related to the change in structure of molten oxides, the silicate tetrahedral Q-species, calculated from the modified quasichemical model with an optimized thermodynamic database, were used as basic structural units in the present model. Experimental molar volume data for unary and binary melts in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbO-Al2O3-SiO2 system were critically evaluated. The molar volumes of unary oxide components and binary Q-species, which are model parameters of the present structural model, were determined to accurately reproduce the experimental data across the entire binary composition in a wide range of temperatures. The non-linear behavior of molar volume and thermal expansivity of binary melt depending on SiO2 content are well reproduced by the present model.

  11. РАСТВОРИМОСТЬ В СИСТЕМЕ K2O-HFO2-AQ-H2O ПРИ 25 °С

    OpenAIRE

    Кострикин, А.; Кузнецова, Р.; Спиридонов, Ф.; Линько, И.; Komissarova, L.; Ezho, A.

    2007-01-01

    Изучена растворимость в системе K2O-HfO2-aq-H2O при 25 °С. Установлено образование в этой системе соединений: НЮ2-Н2О; K2Hf2Oy9H2O и K2Hf(OH)2-0,5H2O. Эти соединения охарактеризованы физико-химическими методами анализа.

  12. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    International Nuclear Information System (INIS)

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of ∼9deg was observed in the φ-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first ∼0.5 μm from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the substrate normal have a unique orientation relationship with the ISD MgO films. An orientation relationship of YBCO(100)||MgO(111) and YBCO(010)||MgO(110) was measured by x-ray pole figure analyses and confirmed by transmission electron microscopy. A Tc of 91 K with a sharp transition and transport Jc of 5.5 x 105 A cm-2 at 77 K in self-field were measured on a YBCO film that was 0.46 μm thick, 4 mm wide and 10 mm long

  13. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    Secondary creep of polycrystalline MgO with grain sizes of 100 and 190 μm was investigated at 1300° to 1460°C under compressive loads of 2.5 to 5.5 kgf/mm2. The dependence of creep rate on load follows a power law with an exponent of 3.2±0.3. The process is thermally activated, with an activation...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...

  14. A Redetermination of the Dissociation Energy of MgO(+)

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1994-01-01

    In 1986, we reported a dissociation energy (D(sub 0) of 2.31 eV for the X(sup 2)Pi ground state of MgO(+). This value was determined by computing the dissociation energy to the Mg(2+) + O(-) limit and adjusting the value to the Mg(+) + O limit using the experimental Ionization Potential (IP) of Mg(+) and the Electron Affinity (EA) of O. The success of this method relies on the assumption that there is little covalent contribution to the bonding. The very small (0.04 eV) correlation contribution to the binding energy was taken as corroboration for the validity of this approach. Our earlier theoretical value was estimated to be accurate to at least 0.2 eV. It is in excellent agreement with the subsequent value of 2.30 +/- 0.13 eV determined by Freiser and co-workers from photodissociation experiments. It is also consistent with the upper (less than 3.1 eV) and lower (greater than 1.1 eV) bounds determined by Rowe obtained by studying the reactions of Mg(+) with 03 and NO2. However, it is inconsistent with an upper bound of 1.7 eV reported by Kappes and Staley based on their failure to observe MgO(+) in the reaction of Mg(+) with N2O. The picture became somewhat clouded, however, by the recent guided-ion beam mass spectrometric studies of Dalleska and Armentrout. Their initial analysis of the reaction data for Mg(+) + O2 lead to a bond dissociation energy of 2.92 +/- 0.25 eV, which is considerably larger than the value of 2.47 +/- 0.06 eV deduced from their studies of the Mg(+)+NO2 reaction.

  15. gold mineralization in Masjeddaghi area, east of Jolfa, NW Iran

    Directory of Open Access Journals (Sweden)

    Ali Imamalipour

    2010-11-01

    Full Text Available Two types of mineralization including porphyry copper and epithermal gold mineralization have occurred in relation with an intermediate volcano-plutonic complex in Masjeddaghi area. Different alterations including silica, advanced argillic, intermediate argillic and propylitic have been distinguished in relation with epithermal mineralization, which have a zonal pattern. Elemental mass gains and losses during alterations were calculated using Zr as an immobile monitor. Silica zone has enriched in SiO2 and relatively in Al2O3 and K2O, and has depleted in Na2O, MgO and CaO. Ba, Sr, Pb, Rb and Cu elements have also enriched. The advanced argillic zone shows enrichment in SO3, Al2O3, SiO2, K2O, MgO and L.O.I; and depletion in Fe2O3, CaO, Na2O, MnO and MgO. Barium, Cu, Sr and Zn have depleted in this zone. Propylitic zone has enriched in MgO, CaO, L.O.I and SiO2, and has depleted in Na2O and K2O. Geochemical and mineralogical evidences indicate that the hydrothermal leaching of mafic minerals in parent rocks and formation of quartz, kaolinite, sericite and alunite assemblage in advanced argillic zone; and chlorite, epidote and calcite assemblage in propylitic zone is responsible for the above mentioned chemical variations. It is likely that the gains and losses of elements have been controlled by agents such as water/rock ratios, temperature changes and chemistry of hydrothermal solutions. The CIA and MIA indicators in the altered rocks indicate the intensity of alteration in silica and advanced argillic zones in comparison with propylitic zone.

  16. New insight in oxidative conversion of alkanes : exploring Li-promoted MgO catalysts and plasma micro-reactors

    NARCIS (Netherlands)

    Trionfetti, Cristiano

    2008-01-01

    In this study the preparation of Li-promoted MgO catalysts is described using, respectively, (i) wet impregnation and (ii) sol-gel method. In the case of Li-promoted MgO catalysts, defects sites, due to the surface substitution of Mg2+ ions by a Li+ ion in the MgO matrix, are reported to play a sign

  17. A conception of formation and operation of CaO coating in regime of self-healing

    International Nuclear Information System (INIS)

    Based on analysis of test results and literature data, a phenomenological model of components interaction in Li[Ca]-V[O] system is proposed. The model demonstrates a cyclic process. Each cycle consists of: I - oxygen transfer from vanadium into lithium; II - CaO layer grows and simultaneously titanium oxides dissolve and oxygen and titanium spreading into solid solution; III - liquid metal penetration into solid metal according to the mechanism of reactionary diffusion accompanied by triple oxide formation; IV - decay of a meta-stable triple oxide and recovering of CaO layer. Within the framework of the proposed model the possible behavior of a CaO coating under isothermal condition is considered

  18. The Sentimental Feelings in Cao Pi's Fu%论曹丕赋中的感伤情怀

    Institute of Scientific and Technical Information of China (English)

    张靖

    2012-01-01

    曹丕的赋具有很强的抒情性,由于特殊的政治地位和人生遭遇,使得曹丕在其赋中流露出凄凉哀婉的心境,以及孤立无援的精神状态,展现了曹丕精神世界中敏感脆弱的一面。%Cao Pi' s Fu has strong lyricism due to the special political status and life experience. Cao Pi in his ode re- veals the desolate pathos mood, as well as the isolated and helpless mental state, which shows Cao Pi' s spiritual world of fragile and sensitive side.

  19. Self-healing of defects in CaO coatings on V-5%Cr-5%Ti in liquid lithium

    International Nuclear Information System (INIS)

    In-situ electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5-85 wt % dissolved Ca was measured as a function of time at temperatures between 250 and 600 degrees C. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at >360 degrees C

  20. Intense 31-35Ar beams produced with a nanostructured CaO target at ISOLDE

    DEFF Research Database (Denmark)

    Ramos, J. P.; Gottberg, A.; Mendonça, T. M.;

    2014-01-01

    At the ISOLDE facility at CERN, thick targets are bombarded with highly energetic pulsed protons to produce radioactive ion beams (RIBs). The isotopes produced in the bulk of the material have to diffuse out of the grain and effuse throughout the porosity of the material to a transfer line which...... synthesized from the respective carbonate. Taking the results of this study, several changes were made at ISOLDE in terms of the CaO target production, handling and operation in order to produce and maintain the nanostructured CaO. The new target, the first nanostructured target to be operated at ISOLDE...

  1. Ab initio study of the low-lying electronic states of the CaO molecule

    International Nuclear Information System (INIS)

    Graphical abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X1Σ+, a3Π, A'1Π, b3Σ+ and A1Σ+, and the corresponding dipole moment functions have been determined using internally contracted multi-reference configuration interaction approaches. The spectroscopic constants associated with these electronic states are compared to experimental values. The corresponding electronic wavefunctions have also been analyzed using the dipole moment functions. Display Omitted Highlights: → The five lowest electronic states of Cao have been determined ab initio at a high level of accuracy. → Large active space, core-valence correlation and configuration interaction are required. → The multi-configurational nature of the electronic ground state is confirmed as well as its monovalent and divalent ionic nature using dipole moment analysis. → These interacting potentials will serve for future obtention of spin-rovibronic levels. - Abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X1Σ+, a3Π, A'1Π, b3Σ+ and A1Σ+, and the corresponding dipole moment functions have been determined using internally contracted multi-reference configuration interaction approaches

  2. Evaporation mechanisms of MgO in laser assisted atom probe tomography

    International Nuclear Information System (INIS)

    In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. -- Research Highlights: →Field evaporation properties of bulk MgO are compared with thin film. →MgO sandwiched between Fe layers. →Evaporation process in two steps in two different time scales. →The change in the thickness of the MgO layer(from 4 to 32nm) does not change the evaporation behavior.

  3. Influence of different ions doping on the antibacterial properties of MgO nanopowders

    International Nuclear Information System (INIS)

    Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li+, Zn2+ and Ti4+) were synthesized by a sol–gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.

  4. Microstructural, optical and magnetic properties study of nanocrystalline MgO

    International Nuclear Information System (INIS)

    Nanocrystalline MgO is prepared by precipitation method. It has a crystallite size of 13 nm. The particles are agglomerated with varied size ranges. N2 adsorption–desorption isotherm confirms the mesoporous structure of MgO nanoparticles with a surface area of 145 m2 g−1. MgO contains hydride related impurities as evidenced from the Fourier transform infrared (FTIR) spectroscopy results. The UV-vis absorption spectrum of MgO contains several visible absorption peaks mostly associated with oxygen vacancies. These oxygen vacancies trap electrons and form color centers such as F, F +, F 2+, F 2 2+, etc. Photoluminescence (PL) and photoluminescence excitation (PLE) results have revealed that the UV and visible emission peaks of MgO result from these color centers. MgO also exhibits room temperature ferromagnetism. Vacuum annealing, however, reduces the magnetization. Thus, the observed magnetism may not be associated with oxygen vacancies. It is the Mg vacancy which is most likely promoting ferromagnetism in nanoscale MgO. (papers)

  5. Synthesis and characterization of mesoporous MgO by template-free hydrothermal method

    International Nuclear Information System (INIS)

    Highlights: • A simple synthesis of porous MgO with diameter size from 3 to 10 μm without any templates. • Effect of temperature and time were investigated. • Systematic characterization by TG/DTA, XRD, SEM, TEM, and nitrogen adsorption–desorption isotherm of MgO. • A possible formation and crystal growth mechanism of mesopores MgO is proposed. - Abstract: Mesoporous MgO particles have been synthesized through a novel template-free hydrothermal co-precipitation method using a Mg(NO3)2 solution as the magnesium source and NaCO3 as precipitant. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N2 adsorption–desorption analysis. The results indicate that the MgO samples have a disordered mesoporous structure, a large BET surface area, and a large pore volume. The effect of reaction temperature on the MgO product BET surface area was studied. A possible formation and crystal growth mechanism for mesoporous MgO is proposed

  6. Pulsed laser deposition of YBCO films on ISD MgO buffered metal tapes

    CERN Document Server

    Ma, B; Koritala, R E; Fisher, B L; Markowitz, A R; Erck, R A; Baurceanu, R; Dorris, S E; Miller, D J; Balachandran, U

    2003-01-01

    Biaxially textured magnesium oxide (MgO) films deposited by inclined-substrate deposition (ISD) are desirable for rapid production of high-quality template layers for YBCO-coated conductors. High-quality YBCO films were grown on ISD MgO buffered metallic substrates by pulsed laser deposition (PLD). Columnar grains with a roof-tile surface structure were observed in the ISD MgO films. X-ray pole figure analysis revealed that the (002) planes of the ISD MgO films are tilted at an angle from the substrate normal. A small full-width at half maximum (FWHM) of approx 9deg was observed in the phi-scan for ISD MgO films deposited at an inclination angle of 55deg . In-plane texture in the ISD MgO films developed in the first approx 0.5 mu m from the substrate surface, and then stabilized with further increases in film thickness. Yttria-stabilized zirconia and ceria buffer layers were deposited on the ISD MgO grown on metallic substrates prior to the deposition of YBCO by PLD. YBCO films with the c-axis parallel to the...

  7. Role of MgO impurity on the superconducting properties of MgB2

    International Nuclear Information System (INIS)

    Highlights: • Multiphase Rietveld refinement and presence of MgO volume fraction in MgB2. • Inhomogeneity in superconducting transition of MgB2 due to hidden MgO. • Diamagnetic and paramagnetic Meissner effect in MgB2. - Abstract: We address the effect of MgO impurity on the superconducting properties of MgB2. The synthesis of MgB2 is very crucial because of sensitivity of Mg to oxidation which may lead to MgO as a secondary phase. Rietveld refinement was performed to determine the quantitative volume fraction of MgO in the samples synthesized by two different techniques. Both the samples were subjected to magnetization measurements under dc and a.c. applied magnetic fields and the observed results were compared as a function of temperature. Paramagnetic Meissner effect has been observed in a sample of MgB2 having more amount of MgO (with Tc = 37.1 K) whereas the pure sample MgB2 having minor quantity of MgO shows diamagnetic Meissner effect with Tc = 38.8 K. M–H measurements at 10 K reveal a slight difference in irreversibility field which is due to MgO impurity along with wide transition observed from ac magnetic susceptibility measurements. The magnetotransport measurements ρ(T) using ρN = 90%, 50% and 10% criterion on pure sample of MgB2 has been used to determine the upper critical field whereas the sample having large quantity of MgO does not allow these measurements due to its high resistance

  8. Epitaxial growth and properties of cubic WN on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Ozsdolay, B.D. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Mulligan, C.P. [U.S. Army Armament Research Development & Engineering Center, Benet Laboratories, Watervliet, NY 12189 (United States); Guerette, Michael; Huang, Liping [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Gall, D., E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2015-09-01

    Tungsten nitride layers, 1.45-μm-thick, were deposited by reactive magnetron sputtering on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001) in 20 mTorr N{sub 2} at 700 °C. X-ray diffraction ω-2θ scans, ω-rocking curves, φ scans, and reciprocal space maps show that all layers exhibit a cubic rock salt structure, independent of their N-to-W ratio which ranges from x = 0.83–0.93, as determined by energy dispersive and photoelectron spectroscopies. Growth on MgO(001) leads to an epitaxial WN(001) layer which contains a small fraction of misoriented grains, WN(111)/MgO(111) is an orientation- and phase-pure single-crystal, and WN/Al{sub 2}O{sub 3}(0001) exhibits a 111-preferred orientation containing misoriented cubic WN grains as well as N-deficient BCC W. Layers on MgO(001) and MgO(111) with x = 0.92 and 0.83 have relaxed lattice constants of 4.214 ± 0.005 and 4.201 ± 0.031 Å, respectively, indicating a decreasing lattice constant with an increasing N-vacancy concentration. Nanoindentation provides hardness values of 9.8 ± 2.2, 12.5 ± 1.0, and 10.3 ± 0.4 GPa, and elastic moduli of 240 ± 40, 257 ± 13, and 242 ± 10 GPa for layers grown on MgO(001), MgO(111), and Al{sub 2}O{sub 3}(0001), respectively. Brillouin spectroscopy measurements yield shear moduli of 120 ± 2 GPa, 114 ± 2 GPa and 108 ± 2 GPa for WN on MgO(001), MgO(111) and Al{sub 2}O{sub 3}(0001), respectively, suggesting a WN elastic anisotropy factor of 1.6 ± 0.3, consistent with the indentation results. The combined analysis of the epitaxial WN(001) and WN(111) layers indicate Hill's elastic and shear moduli for cubic WN of 251 ± 17 and 99 ± 8 GPa, respectively. The resistivity of WN(111)/MgO(111) is 1.9 × 10{sup −5} and 2.2 × 10{sup −5} Ω-m at room temperature and 77 K, respectively, indicating weak carrier localization. The room temperature resistivities are 16% and 42% lower for WN/MgO(001) and WN/Al{sub 2}O{sub 3}(0001), suggesting a resistivity decrease with decreasing

  9. Teoría del caos y sus posibles implicaciones en psicología

    OpenAIRE

    Dan Eric Luévano Ramírez

    2004-01-01

    En el presente artículo se exploran las nuevas posibilidades que brinda la teoría del caos en la psicología como modelo conceptual o metodológico. Comienza con una breve historia de los movimientos en la filosofía de la ciencia y cómo estos han afectado a la psicología en su constitución en estos últimos ochenta años y en su modo de hacer investigación; se explora después el método científico y su utilización en la psicología con sus limitantes y fallas; por ultimo, se explica ...

  10. Study on the Surface Free Energy of Ground CaO by IGC

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    CaO formed by decomposing CaCO3 at 1450℃ was ground in a vibrational mill,then the long-time ground sample was reheated at different temperatures.Inverse Gas Chromatography (IGC) was used to measure the variation of the sample′s surface free energy under grinding and reheating.It is concluded that the total surface free energy and the London dispersive component of the surface free energy increases with grinding,while the polar component first increases with grinding,and then decreases,and finally disappears.When the long-time ground sample was reheated,its total surface free energy decreases,among which the London component decreases,but the polar component appears again.

  11. Caos, complexidade e Lingüística Aplicada: diálogos transdisciplinares

    Directory of Open Access Journals (Sweden)

    Antônio Carlos Soares Martins

    2007-01-01

    Full Text Available Neste texto, apresentamos um panorama de estudos na área da Lingüística Aplicada que discutem questões relativas ao processo de desenvolvimento de segunda língua, bem como aspectos relacionados aos ambientes interacionais de aprendizagem na perspectiva das teorias do Caos e Complexidade. Para isso, discutimos as principais noções da perspectiva da complexidade, retomando alguns aspectos da física clássica e contemporânea.In this paper, we present a panorama of studies in the area of Applied Linguistics that discuss questions regarding second language development as well as aspects related to interactional learning environments in the light of Chaos and Complexity theories. To accomplish this, we discuss the main notions of complexity through the rethinking of some aspects of classic and contemporary physics.

  12. Teoría del caos, cognitivismo y semántica

    Directory of Open Access Journals (Sweden)

    Lic. Raymond Colle

    1998-01-01

    Full Text Available El origen del pensamiento no tiene nada de secuencial: el cerebro es un "mecanismo" que opera con una altísima tasa de paralelismo. Es también un sistema altamente complejo y comparte algunas características de funcionamiento de todos los sistemas altamente complejos. En este artículo se citan a diversos investigadores que han puesto en evidencia los fenómenos de aparición del orden en medio del "caos" en sistemas complejos; se explica cómo el pensamiento se ordena en torno a "atractores", formando "mapas" de relaciones y se ilustra con un caso practico cómo este mapa aparece en nuestros discursos.

  13. Single-Crystal MgO Hollow Nanospheres Formed in RF Impulse Discharge Plasmas

    International Nuclear Information System (INIS)

    Spherical MgO nanoparticles with a hollow inside, that is, MgO hollow nanospheres, were created in Ar/O2 plasma produced by radio frequency (RF) impulse discharge using a Mg rod electrode. The hollow nanospheres were found on the SiO2 plates placed near the powered Mg electrode. The electron refraction pattern showed that each nanosphere was made of a single crystal of MgO. Since the shape was spherical, these nanoparticles seemed to be created during the levitation in the plasma without touching any walls. The formation mechanism with a quasiliquid cooling model was also discussed.

  14. One-step synthesis of MgO hollow nanospheres with blue emission

    International Nuclear Information System (INIS)

    MgO hollow nanospheres were produced via one-step laser synthesis in both gas and liquid media. The formation mechanism of MgO hollow nanospheres was investigated by adopting high-speed photography and performing control experiments under different oxidization conditions. The results indicated that the in situ Kirkendall effect is responsible for the formation of the hollow nanospheres. Blue emission was observed from the MgO hollow nanospheres produced in a liquid medium, and is ascribed to the surface state arising from the organic modification.

  15. MgO Doped Tantalum Coating on Ti: Microstructural Study and Biocompatibility Evaluation

    OpenAIRE

    Roy, Mangal; Balla, Vamsi Krishna; Bandyopadhyay, Amit; Bose, Susmita

    2012-01-01

    Pure and MgO incorporated Ta coatings were prepared on Cp-Ti substrate using laser engineered net shaping (LENS™) which resulted in diffuse coating-substrate interface. MgO was found along the Ta grain boundaries in the Ta matrix that increased the coating hardness from 185 ± 2.7 HV to 794 ± 93 HV. In vitro biocompatibility study showed excellent early cellular attachment and later stage proliferation in MgO incorporated coatings. The results indicated that although Ta coatings had higher bio...

  16. Perpendicular magnetization of Co20Fe50Ge30 films induced by MgO interface

    OpenAIRE

    Ding, Manli; Poon, S. Joseph

    2013-01-01

    Epitaxial growth of Co20Fe50Ge30 thin film on single crystal MgO (001) substrate is reported. Structure characterization revealed (001)-oriented B2 order of CoFeGe well lattice matched with the MgO barrier. Perpendicular magnetic anisotropy (PMA) was achieved in the MgO/CoFeGe/MgO structure with an optimized magnetic anisotropy energy density (K) of 3 106 erg/cm3. The magnetic anisotropy is found to depend strongly on the thickness of the MgO and CoFeGe layers, indicating that the PMA of CoFe...

  17. Disorder, defects and bandgaps in ultra thin (001) MgO tunnel barrier layers

    OpenAIRE

    Mather, P. G.; Read, J. C.; Buhrman, R.A.

    2006-01-01

    We report scanning tunneling spectroscopy studies of the electronic structure of 1.5 to 3 nm (001) textured MgO layers grown on (001) Fe. Thick MgO layers exhibit a bulk-like band gap, approximately 5-7 eV, and sparse, localized defect states with characteristics attributable to oxygen and, in some cases, Mg vacancies. Thin MgO layers exhibit electronic structure indicative of interacting defect states forming band tails which in the thinnest case extend to approximately 0.5 V of the Fermi le...

  18. The Adsorption Study of Methylene Blue onto MgO from Various Preparation Methods

    OpenAIRE

    R. Wanchanthuek; W. Nunrung

    2011-01-01

    The investigation of Methylene Blue (MB) removal in solution by Magnesium Oxide (MgO) from various preparation methods was studied. Then, these adsorbents were characterized for the surface morphology using Scanning Electron Microscopy (SEM). Moreover, the effect of preparation parameters in MB adsorption onto resulted MgO such as aging time, drying temperature and calcinations temperature was also examined. The MgO was the precipitation of Mg(OH)2 by using Mg(NO3)2.6H2O as Mg metal source an...

  19. Role of MgO impurity on the superconducting properties of MgB2

    OpenAIRE

    Singh, Dharmendra Kumar; Tiwari, Brajesh; Jha, Rajveer; Kishan, H.; Awana, V. P. S.

    2014-01-01

    We address the effect of MgO impurity on the superconducting properties of MgB2. The synthesis of MgB2 is very crucial because of sensitivity of Mg to oxidation which may lead to MgO as a secondary phase. Rietveld refinement was performed to determine the quantitative volume fraction of MgO in the samples synthesized by two different techniques. Both the samples were subjected to magnetization measurements under dc and ac applied magnetic fields and the observed results were compared as a fun...

  20. Enhancement effect of micropore filling for supercritical methane by MgO dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Katsumi; Murata, Katsuyuki; Shimizu, Kazuyuki; Camara, Sory; Suzuki, Takaomi (Chiba Univ. (Japan))

    1993-05-01

    Pitch-based activated carbon fiber (ACF) was modified with MgO fine particles. The high pressure methane adsorption isotherms of ACF and MgO-dispersed ACF were determined at 303 K. These isotherms were Langmurian. The MgO dispersion markedly enhanced the methane adsorptivity of ACF. The saturated amount of methane adsorption for MgO-dispersed ACF was 1.5 times greater than that of ACF in terms of milligrams per gram; even the methane adsorption per micropore volume was remarkably enhanced by the MgO dispersion. 18 refs., 4 figs., 2 tabs.

  1. Single-Crystal MgO Hollow Nanospheres Formed in RF Impulse Discharge Plasmas

    Directory of Open Access Journals (Sweden)

    Satoru Iizuka

    2012-01-01

    Full Text Available Spherical MgO nanoparticles with a hollow inside, that is, MgO hollow nanospheres, were created in Ar/O2 plasma produced by radio frequency (RF impulse discharge using a Mg rod electrode. The hollow nanospheres were found on the SiO2 plates placed near the powered Mg electrode. The electron refraction pattern showed that each nanosphere was made of a single crystal of MgO. Since the shape was spherical, these nanoparticles seemed to be created during the levitation in the plasma without touching any walls. The formation mechanism with a quasiliquid cooling model was also discussed.

  2. Mesoporous MgO: Synthesis, physico-chemical, and catalytic properties

    Science.gov (United States)

    Maerle, A. A.; Kasyanov, I. A.; Moskovskaya, I. F.; Romanovsky, B. V.

    2016-06-01

    Mesoporous MgO was obtained via the hydrothermal synthesis using both ionogenic and non-ionogenic surfactants as structure-directing templates. The materials prepared were characterized by SEM, BET-N2, XRD, and TG-DTA techniques. MgO particles are spherical 20-μm aggregates of primary oxide particles well shaped as rectangular parallelepipeds. Magnesium oxide samples have the specific surface area of 290-400 m2/g and pore sizes of 3.3-4.1 nm. Their mesoporous structure remained unchanged after calcination up to 350°C. Catalytic activity of mesoporous MgO was studied in acetone condensation reaction.

  3. ExoMol molecular line lists - XIII. The spectrum of CaO

    Science.gov (United States)

    Yurchenko, Sergei N.; Blissett, Audra; Asari, Usama; Vasilios, Marcus; Hill, Christian; Tennyson, Jonathan

    2016-03-01

    An accurate line list for calcium oxide is presented covering transitions between all bound ro-vibronic levels from the five lowest electronic states X 1Σ+, A' 1Π, A 1Σ+, a 3Π, and b 3Σ+. The ro-vibronic energies and corresponding wavefunctions were obtained by solving the fully coupled Schrödinger equation. Ab initio potential energy, spin-orbit, and electronic angular momentum curves were refined by fitting to the experimental frequencies and experimentally derived energies available in the literature. Using our refined model we could (1) reassign the vibronic states for a large portion of the experimentally derived energies (van Groenendael A., Tudorie M., Focsa C., Pinchemel B., Bernath P. F., 2005, J. Mol. Spectrosc., 234, 255), (2) extended this list of energies to J = 61-118 and (3) suggest a new description of the resonances from the A 1Σ+-X 1Σ+ system. We used high level ab initio electric dipole moments reported previously (Khalil H., Brites V., Le Quere F., Leonard C., 2011, Chem. Phys., 386, 50) to compute the Einstein A coefficients. Our work is the first fully coupled description of this system. Our line list is the most complete catalogue of spectroscopic transitions available for 40Ca16O and is applicable for temperatures up to at least 5000 K. CaO has yet to be observed astronomically but its transitions are characterized by being particularly strong which should facilitate its detection. The CaO line list is made available in an electronic form as supplementary data to this article and at www.exomol.com.

  4. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere .

    Science.gov (United States)

    Della Corte, V.; Rietmeijer, F. J. M.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    Nanometer- to micrometer-size particles present in the upper stratosphere are a mixture of terrestrial and extra-terrestrial origins. They can be extraterrestrial particles condensed after meteor ablation. Meteoric dust in bolides is occasionally deposited into the lower stratosphere around 20 km altitude. Nanometer CaO and pure carbon smoke particles were collected at 38 km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO_3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth� atmosphere. For the first time, DUSTER collected meteor ablation products that were presumably associated with the disintegration of a bolide crossing the Earth's atmosphere. The collected mostly CaO and pure carbon nanoparticles from the debris cloud of a fireball, included: 1) intact fragments; 2) quenched melted grains; and 3) vapor phase condensation products. The DUSTER project was funded by the Italian Space Agency (ASI), PRIN2008/MIUR (Ministero dell'Istruzione dell'Universitá e della Ricerca), PNRA 2013(Piano Nazionale Ricerca Antartide). CNES graciously provided this flight opportunity. We thank E. Zona and S. Inarta at the Laboratorio di Fisica Cosmica INAF, Osservatorio Astronomico di Capodimonte-Universitá di Napoli Parthenope. F.J.M.R. was supported by grant NNX07AI39G from the NASA Cosmochemistry Program. We thank three anonymous reviewers who assisted us in introducing our new instrument.

  5. La anticipación de las crisis (una aplicación del enfoque del caos

    Directory of Open Access Journals (Sweden)

    Manuel Guzmán Hennessey

    2007-01-01

    Full Text Available Este ensayo explora la posibilidad de aplicar la teoría del caos en el contexto de las dinámicas de crisis. Se examinan las bases filosóficas del pensamiento cognitivo borroso y se explora un modelo de aproximación a la realidad, a partir del reconocimiento de sus ciclos evolutivos caos orden. El problema de ver es la línea de investigación del Centro de Aplicaciones de la Teoría del Caos (Bogotá, Buenos Aires. Este trabajo es un avance de la investigación “Mil Matices: materiales para una teoría de las crisis”, cuyo propósito, entre otros, plantea: ¿Cuál es, en realidad, la esencia y el origen del Caos, y cómo pueden aplicarse sus enfoques en una sociedad que necesita superar sus crisis y aprender a moverse en contextos turbulentos?

  6. CaO insulator coatings on a vanadium-base alloy in liquid 2 at.% calcium-lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, IL (United States)

    1996-10-01

    The electrical resistance of CaO coatings produced on V-4%Cr-4%Ti and V-15%Cr-5%Ti by exposure of the alloy (round bottom samples 6-in. long by 0.25-in. dia.) to liquid lithium that contained 2 at.% dissolved calcium was measured as a function of time at temperatures between 300-464{degrees}C. The solute element, calcium in liquid lithium, reacted with the alloy substrate at these temperatures for 17 h to produce a calcium coating {approx}7-8 {mu}m thick. The calcium-coated vanadium alloy was oxidized to form a CaO coating. Resistance of the coating layer on V-15Cr-5Ti, measured in-situ in liquid lithium that contained 2 at.% calcium, was 1.0 x 10{sup 10} {Omega}-cm{sup 2} at 300{degrees}C and 400 h, and 0.9 x 10{sup 10} {Omega}-cm{sup 2} at 464{degrees}C and 300 h. Thermal cycling between 300 and 464{degrees}C changed the resistance of the coating layer, which followed insulator behavior. Examination of the specimen after cooling to room temperature revealed no cracks in the CaO coating. The coatings were evaluated by optical microscopy, scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and X-ray analysis. Adhesion between CaO and vanadium alloys was enhanced as exposure time increased.

  7. Interface structure of Nb films on single crystal MgO(1 0 0) and MgO(1 1 1) substrates

    International Nuclear Information System (INIS)

    This study systematically investigates the interface structure of Nb films grown on MgO substrates with different orientations ((1 0 0) and (1 1 1)) by experiments and simulations. X-ray diffraction, transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to characterize the structure of Nb films and the structure of interfaces between Nb films and MgO substrates. The results show that thin films exhibit different preferred planes on different orientations of MgO substrates. First-principles calculations were used to understand the interface configuration through a coherent interface model. The combination of experiments and simulations shows that the work of separation, together with substrate orientation and lattice mismatch, determines the interface structure between films and substrates

  8. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Danith; Chikkahanumantharayappa [Dept. of Physics, Vivekananda First grade College, Bangalore - 560055 (India); Yadav, L. S. Reddy; Nagaraju, G., E-mail: nagarajugn@rediffmail.com [Dept of Chemistry, Siddaganga Institute of Technology, Tumkur, Karnataka-572103 (India); Lingaraju, K.; Naika, H. Raja [Dept. of Environmental Science, Tumkur University, Tumkur, Karnataka-572103 (India); Manjunath, K. [Centre for Nano and Material Sciences, Jain University, Jakkasandra, Karnataka-562112 (India); Suresh, D. [Dept. of Chemistry, Tumkur University, Tumkur, Karnataka-572103 (India); Prasad, Daruka [Dept. of Physics, BMS Institute of Technology, Bangalore-560064 (India); Nagabhushana, H. [CNR Rao Center for Advanced Materials, Tumkur University, Tumkur, Karnataka-572103 (India); Sharma, S. C. [Chattisgarh Swami Vivekananda Technological University, Bhilai, Chattisgarh-490009 (India)

    2015-06-24

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  9. Regenerable MgO promoted metal oxide oxygen carriers for chemical looping combustion

    Science.gov (United States)

    Siriwardane, Ranjani V.; Miller, Duane D.

    2014-08-19

    The disclosure provides an oxygen carrier comprised of a plurality of metal oxide particles in contact with a plurality of MgO promoter particles. The MgO promoter particles increase the reaction rate and oxygen utilization of the metal oxide when contacting with a gaseous hydrocarbon at a temperature greater than about 725.degree. C. The promoted oxide solid is generally comprised of less than about 25 wt. % MgO, and may be prepared by physical mixing, incipient wetness impregnation, or other methods known in the art. The oxygen carrier exhibits a crystalline structure of the metal oxide and a crystalline structure of MgO under XRD crystallography, and retains these crystalline structures over subsequent redox cycles. In an embodiment, the metal oxide is Fe.sub.2O.sub.3, and the gaseous hydrocarbon is comprised of methane.

  10. Application of shell model in molecular dynamics simulation to MgO

    Institute of Scientific and Technical Information of China (English)

    Liu Zi-Jiang; Cheng Xin-Lu; Chen Xiang-Rong; Zhang Hong; Lu Lai-Yu

    2004-01-01

    The P-V-T equation of state of MgO has been simulated under high pressure and elevated temperature using the molecular dynamics (MD) method with the breathing shell model (BSM). It is found that the MD simulation with BSM is very successful in reproducing accurately the measured molar volumes of MgO over a wide range of temperature and pressure. In addition, the MD simulation reproduces accurately the measured volume compression data of MgO up to 100GPa at 300K. It is demonstrated that the MD simulated P-V-T equation of state of MgO could be applied as a useful internal pressure calibration standard at elevated temperatures and high pressures.

  11. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    Science.gov (United States)

    Kumar, Danith; Yadav, L. S. Reddy; Lingaraju, K.; Manjunath, K.; Suresh, D.; Prasad, Daruka; Nagabhushana, H.; Sharma, S. C.; Naika, H. Raja; Chikkahanumantharayappa, Nagaraju, G.

    2015-06-01

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm-1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV -Vis spectrum was found to be in the range 5.40-5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

  12. Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

    International Nuclear Information System (INIS)

    Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm−1 indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation

  13. Analysis of isothermal sintering of zinc-titanate doped with MgO

    Directory of Open Access Journals (Sweden)

    Obradović N.

    2007-01-01

    Full Text Available The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5% were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate.

  14. Discrete Layer-by-Layer Magnetic Switching in Fe /MgO (001 ) Superlattices

    Science.gov (United States)

    Moubah, R.; Magnus, F.; Warnatz, T.; Palsson, G. K.; Kapaklis, V.; Ukleev, V.; Devishvili, A.; Palisaitis, J.; Persson, P. O. Å.; Hjörvarsson, B.

    2016-04-01

    We report on a discrete layer-by-layer magnetic switching in Fe /MgO superlattices driven by an antiferromagnetic interlayer exchange coupling. The strong interlayer coupling is mediated by tunneling through MgO layers with thicknesses up to at least 1.8 nm, and the coupling strength varies with MgO thickness. Furthermore, the competition between the interlayer coupling and magnetocrystalline anisotropy stabilizes both 90° and 180° periodic alignment of adjacent layers throughout the entire superlattice. The tunable layer-by-layer switching, coupled with the giant tunneling magnetoresistance of Fe /MgO /Fe junctions, is an appealing combination for three-dimensional spintronic memories and logic devices.

  15. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    Secondary creep of polycrystalline MgO with grain sizes of 100 and 190 μm was investigated at 1300° to 1460°C under compressive loads of 2.5 to 5.5 kgf/mm2. The dependence of creep rate on load follows a power law with an exponent of 3.2±0.3. The process is thermally activated, with an activation...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...... dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...

  16. Strengthening and toughening of poly(L-lactide) composites by surface modified MgO whiskers

    International Nuclear Information System (INIS)

    Highlights: • The grafted PLLA chain on the surface of g-MgO whisker was ruled out by FTIR spectroscopy and TG/DTG analyses. • The excellent dispersion of g-MgO whiskers and the strong interfacial adhesion of g-MgO whiskers/PLLA composite were proved by FSEM. • Comparing to MgO particles and MgO whiskers, fibrous-like g-MgO whiskers are the most effective reinforcing and toughening fillers for PLLA. - Abstract: To improve both the strength and toughness of poly(L-lactide) (PLLA), fibrous-like MgO whiskers with diameters of 0.15–1 μm and lengths of 15–110 μm were prepared, and subsequently surface modified with L-lactide to obtain grafted MgO whiskers (g-MgO whiskers). The structures and properties of MgO whiskers and g-MgO whiskers were studied. Then, a series of MgO whiskers/PLLA and g-MgO whiskers/PLLA composites were prepared by solution casting method, for comparison, MgO particles/PLLA composite was prepared too. The resulting composites were evaluated in terms of hydrophilicity, crystallinity, dispersion of whiskers, interfacial adhesion and mechanical performance by means of polarized optical microscopy (POM), contact angle measurement, field emission scanning electron microscope (FSEM), transmission electron microscopy (TEM) and tensile testing. The results revealed that the crystallization rate and hydrophilicity of PLLA were improved by the introduction of MgO whiskers and g-MgO whiskers. The g-MgO whiskers can disperse more uniformly in and show stronger interfacial adhesion with the matrix than MgO whiskers as a result of the surface modification. Due to the bridge effect of the whiskers and the excellent interfacial adhesion between g-MgO whiskers and PLLA, g-MgO whiskers/PLLA composites exhibited remarkably higher strength, modulus and toughness compared to the pristine PLLA, MgO particles/PLLA and MgO whiskers/PLLA composites

  17. Positron annihilation 2D-ACAR study of semi-coherent Li nanoclusters in MgO( 1 0 0 ) and MgO( 1 1 0 )

    Science.gov (United States)

    Falub, C. V.; Mijnarends, P. E.; Eijt, S. W. H.; van Huis, M. A.; van Veen, A.; Schut, H.

    2002-05-01

    Depth selective positron annihilation two-dimensional angular correlation of annihilation radiation (2D-ACAR) is used to determine the electronic structure of Li nanoclusters formed by implantation of 10 16 cm -26Li ions (with an energy of 30 keV) in MgO(1 0 0) and (1 1 0) crystals, and subsequently annealed at 950 K. The 2D-ACAR spectra of Li-implanted MgO obtained with 4 keV positrons reveal the semi-coherent ordering state of the embedded metallic Li nanoclusters. The results agree with ab initio Korringa-Kohn-Rostoker calculations.

  18. Positron annihilation 2D-ACAR study of semi-coherent Li nanoclusters in MgO(1 0 0) and MgO(1 1 0)

    International Nuclear Information System (INIS)

    Depth selective positron annihilation two-dimensional angular correlation of annihilation radiation (2D-ACAR) is used to determine the electronic structure of Li nanoclusters formed by implantation of 1016 cm-26Li ions (with an energy of 30 keV) in MgO(1 0 0) and (1 1 0) crystals, and subsequently annealed at 950 K. The 2D-ACAR spectra of Li-implanted MgO obtained with 4 keV positrons reveal the semi-coherent ordering state of the embedded metallic Li nanoclusters. The results agree with ab initio Korringa-Kohn-Rostoker calculations

  19. Homegardens of the Cao Lan, a Tai-Speaking Ethnic Minority in Vietnam’s Northern Mountains

    Directory of Open Access Journals (Sweden)

    Pijika Timsuksai

    2015-08-01

    Full Text Available The Cao Lan are a Tai-speaking ethnic group living in the Midlands of Northern Vietnam. Homegardens are an important component of their agroecosystem. The ecological structures of each homegarden of 17 households of the Cao Ngoi village in Tuyen Quang province were described and modal patterns identified. Most homegardens have organically shaped planting areas with indeterminate boundaries, polycentric planting patterns, and contain multiple species within the same bed or planting area. All of the gardens have multiple vegetation levels, with the largest share having 5 levels and a majority having more than 50% of their planting area covered by overlapping vegetation layers. Biodiversity is high with a total of 113 species recorded. Most plant species are used for food, but smaller numbers have ornamental, medicinal, and construction uses or are used for animal fodder, as stimulants, or for other purposes. Comparison of the modal structure of the Cao Lan homegardens with several Tai minority groups in Northeast Thailand, shows that, although the Cao Lan have been geographically isolated from other Tai groups for many centuries, their homegardens share a similar structural pattern, one commonly referred to as the tropical forest type. This structure is very different from the temperate type gardens of the Kinh in Vietnam with whom the Cao Lan share a common environment and are in frequent contact. The persistence of a common structural pattern among these related Tai ethnic groups, despite their inhabiting different environments, and having had no direct contact with each other for a very long time, suggests that culture exerts a strong influence over agroecosystem structure.

  20. Studying some mechanical properties of MgO with used neon bulb glass

    Energy Technology Data Exchange (ETDEWEB)

    Issa, Tarik Talib [University of Baghdad, College of science physic department , Material Science group (Iraq); Khaleel, Saba Mahdi [Ministry of Industry and Minerals,Commission for Research And Industrial Development ,Chemical and Petrochemical Research Center, Baghdad (Iraq); Abdul Kareem, Noura Ammar [Ministry of Industry and Minerals, Commission for Research And Industrial Development ,Chemical and Petrochemical Research Center, Baghdad (Iraq)

    2013-12-16

    Ceramic compact of MgO +WT% of UNBG were sintered at different sintering temperature (700, 900, 1100, 1300)°c, under static air for 3 hours. X-ray diffraction and some mechanical properties were conducted. The maximum sintered density, compression; fracture strength and hardness were indicated for the compilation of MgO −20 WT % UNBG, sintered at 1300 °c.

  1. Structural properties of Au and Ag nanoclusters embedded in MgO

    NARCIS (Netherlands)

    Fedorov, A.V.; Veen, A. van; Falub, C.V.; Eijt, S.W.H.; Kooi, B.J.; Hosson, J.Th.M. De; Hibma, T.; Zimmerman, R.L.

    2002-01-01

    Gold and silver nanoclusters embedded in MgO were created by means of ion implantation of 1.0 MeV Au or 600 keV Ag ions to a dose of 10^16 cm–2 into single crystals of MgO(100) and subsequent annealing at 1473 K for a period of 22 h. The structural properties of the nanoclusters were characterised b

  2. Porous MgO material with ultrahigh surface area as the matrix for phase change composite

    International Nuclear Information System (INIS)

    Highlights: • Porous MgO material with ultrahigh surface area was synthesized. • A composite PCM was prepared from PEG-1000 and the porous MgO. • The phase change temperatures and enthalpy of the composite were measured. • The composite PCM performed good shape-stabilized property. - Abstract: Mesoporous magnesium oxide (MgO) material was synthesized using an integration of the evaporation-induced surfactant assembly and magnesium nitrate pyrolysis. The as-prepared MgO material is well crystalline, and possesses three-dimensional interconnected mesopores and a surface area as high as 596 m2/g. Using the porous MgO as a matrix and polyethylene glycol (PEG-1000) as the functional phase for heat energy storage, a shape-stabilized phase change composite of PEG/MgO was fabricated by an easy impregnation method. In the composite, mesoporous MgO material provides structural strength and prevents the leakage of the molten PEG during the phase change process. The compositions and microstructures of the PEG/MgO composite were determined by Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), scanning electronic microscope (SEM) and thermogravimetric analyzer (TGA), respectively. The phase change properties of the PEG/MgO composite were determined by differential scanning calorimeter (DSC). The high heat-energy storage capability and good thermal stability of the composite enable it extensive applications in the future

  3. Synthesis and characterization of MgO nanocrystals for biosensing applications

    International Nuclear Information System (INIS)

    Highlights: • MgO nanocrystals were prepared using DC arc plasma jet CVD method. • The growth time does not exceed 10 min in process of the synthesis. • The samples were found to consist of cubic MgO nanobelts and nanosheets. • Nanocrystals contain contacts, rough edges, vacancies, and doping defects. • The samples exhibited excellent electrochemical biosensing properties. - Abstract: MgO nanocrystals were prepared using a simple direct current arc plasma jet chemical vapor deposition method. Magnesium nitrate was used as source material and Mo film was used as a substrate and catalyst. The high-temperature plasma produced ensured rapid synthesis of the MgO nanocrystals. The as-prepared nanocrystals were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and photoluminescence measurements. The as-synthesized samples were found to consist of cubic MgO nanobelts and nanosheets with large surface areas and low coordination oxide ions, and contained numerous contacts, rough edges, vacancies, and doping defects. The nanostructures exhibited excellent electrochemical sensing properties with high-sensing sensitivity toward ascorbic acid. Their high electrocatalytic activity was attributed to the effect of defects and the surface electron transfer ability of the one-dimensional MgO nanobelts

  4. Characterization of BLT thin films using MgO buffer layer for MFIS-FET

    International Nuclear Information System (INIS)

    The BLT thin film and MgO buffer layer were fabricated using a metalorganic decomposition method and the DC sputtering technique. The MgO thin film was deposited as a buffer layer on SiO2/Si and Bi3.25La0.75Ti3O12 (BLT) thin films were used as a ferroelectric layer. The electrical of the metal ferroelectric insulator semiconductor (MFIS) structure were investigated by varying the MgO layer thickness. Transmission electron microscopy (TEM) shows no interdiffusion and reaction that suppressed by using the MgO film as a buffer layer. The width of the memory window in the C-V curves for the MFIS structure decreased with increasing thickness of the MgO layer. Leakage current density decreased by about three orders of magnitude after using MgO buffer layer. The results show that the BLT and MgO-based MFIS structure is suitable for non-volatile memory FETs with large memory window

  5. Characterization of BLT thin films using MgO buffer layer for MFIS-FET

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung-Tae [School of Electrical and Electronic Engineering, Chungang University, 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Lee, Jung-Mi [School of Electrical and Electronic Engineering, Chungang University, 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Song, Sang-Hun [School of Electrical and Electronic Engineering, Chungang University, 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Kim, Chang-Il [School of Electrical and Electronic Engineering, Chungang University, 221, Huksuk-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of)]. E-mail: cikim@cau.ac.kr

    2005-03-22

    The BLT thin film and MgO buffer layer were fabricated using a metalorganic decomposition method and the DC sputtering technique. The MgO thin film was deposited as a buffer layer on SiO{sub 2}/Si and Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} (BLT) thin films were used as a ferroelectric layer. The electrical of the metal ferroelectric insulator semiconductor (MFIS) structure were investigated by varying the MgO layer thickness. Transmission electron microscopy (TEM) shows no interdiffusion and reaction that suppressed by using the MgO film as a buffer layer. The width of the memory window in the C-V curves for the MFIS structure decreased with increasing thickness of the MgO layer. Leakage current density decreased by about three orders of magnitude after using MgO buffer layer. The results show that the BLT and MgO-based MFIS structure is suitable for non-volatile memory FETs with large memory window.

  6. Synthesis and characterization of MgO nanocrystals for biosensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongji [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Mingji, E-mail: limingji@163.com [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China); Qiu, Guojun [Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Li, Cuiping; Qu, Changqing; Yang, Baohe [Tianjin Key Laboratory of Film Electronic and Communication Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2015-05-25

    Highlights: • MgO nanocrystals were prepared using DC arc plasma jet CVD method. • The growth time does not exceed 10 min in process of the synthesis. • The samples were found to consist of cubic MgO nanobelts and nanosheets. • Nanocrystals contain contacts, rough edges, vacancies, and doping defects. • The samples exhibited excellent electrochemical biosensing properties. - Abstract: MgO nanocrystals were prepared using a simple direct current arc plasma jet chemical vapor deposition method. Magnesium nitrate was used as source material and Mo film was used as a substrate and catalyst. The high-temperature plasma produced ensured rapid synthesis of the MgO nanocrystals. The as-prepared nanocrystals were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, Fourier transform infrared spectrometry, ultraviolet–visible spectrophotometry, and photoluminescence measurements. The as-synthesized samples were found to consist of cubic MgO nanobelts and nanosheets with large surface areas and low coordination oxide ions, and contained numerous contacts, rough edges, vacancies, and doping defects. The nanostructures exhibited excellent electrochemical sensing properties with high-sensing sensitivity toward ascorbic acid. Their high electrocatalytic activity was attributed to the effect of defects and the surface electron transfer ability of the one-dimensional MgO nanobelts.

  7. Epitaxial growth of ultrathin MgO layers on Fe3O4(0 0 1) films

    Science.gov (United States)

    Nordmann, T.; Kuschel, O.; Wollschläger, J.

    2016-09-01

    The initial growth stages of MgO on Fe3O4 films are studied by means of X-ray photoelectron spectroscopy and low energy electron diffraction to clarify stoichiometric and structural properties of these layered structures. This bilayer structure is important to fabricate high quality magnetic tunnel junctions based on Fe3O4 electrodes and MgO tunneling barriers. For this purpose, the deposition temperature of MgO has been varied between 100 °C and 250 °C. Initially, MgO grows layer-by-layer on Fe3O4/MgO(0 0 1) forming a wetting layer. Depending on the growth temperature, after growth of a 2-3 nm thick laminar wetting layer, the MgO films finally start to roughen during growth. Thus the growth of MgO on Fe3O4/MgO(0 0 1) is described by a Stranski-Krastanov growth mode. Diffraction experiments show that the magnetite (√{ 2} ×√{ 2})R45° superstructure is removed already during the initial stages of MgO deposition. Furthermore, these experiments show that MgO films are rougher for growth at low deposition temperatures.

  8. Spatial and temporal variations of water quality in Cao-E River of eastern China

    Institute of Scientific and Technical Information of China (English)

    CHEN Ding-jiang; LU Jun; YUAN Shao-feng; JIN Shu-quan; SHEN Ye-na

    2006-01-01

    Evaluation and analysis of water quality variations were performed with integrated consideration of water quality parameters, hydrological-meteorologic and anthropogenic factors in Cao-E River, Zhejiang Province of China. Cao-E River system has been polluted and the water quality of some reaches are inferior to Grade V according to National Surface Water Quality Standard of China (GB2002). However, mainly polluted indices of each tributary and mainstream are different. Total nitrogen (TN) and total phosphorus (TP) in the water are the main polluted indices for mainstream that varies from 1.52 to 45.85 mg/L and 0.02 to 4.02 mg/L,respectively. TN is the main polluted indices for Sub-watershed Ⅰ, Ⅱ, Ⅳ and Ⅴ (0.76 to 18.27 mg/L). BOD5 (0.36 to 289.5 mg/L),CODMn (0.47 to 78.86 mg/L), TN (0.74 to 31.09 mg/L) and TP (0 to 3.75 mg/L) are the main polluted indices for Sub-watershed Ⅲ.There are tow pollution types along the river including nonpoint source pollution and point source pollution types. Remarkably temporal variations with a few spatial variations occur in nonpoint pollution type reaches (including mainstream, Sub-watershed Ⅰ and Ⅱ) that mainly drained by arable field and/or dispersive rural dwelling district, and the maximum pollutant concentration appears in flooding seasons. It implied that the runoff increases the pollutant concentration of the water in the nonpoint pollution type reaches. On the other hand, remarkably spatial variations occur in the point pollution type reaches (include Sub-watershed Ⅲ, Ⅳ and Ⅴ) and the maximum pollutant concentration appears in urban reaches. The runoff always decreases the pollutant concentration of the river water in the seriously polluted reaches that drained by industrial point sewage. But for the point pollution reaches resulted from centralized town domestic sewage pipeline and from frequent shipping and digging sands, rainfall always increased the concentration of pollutant (TN) in the river water

  9. [Determination of major elements in superphosphate by X-ray fluorescence spectrometry].

    Science.gov (United States)

    Rui, Yu-Kui; Li, He; Shen, Jian-Bo; Zhang, Fu-Suo

    2008-11-01

    Phosphate fertilizer is one of the most important fertilizers. The authors determined nine kinds of major elements in superphosphate, the most important phosphate fertilizer, by X-ray fluorescence spectrometry. The detection range of SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 is 15.0%-90.0%, 0.20%-25.0%, 0.20%-25.0%, 0.01%-0.35%, 0.20%-40.0%, 0.10%-35.0%, 0.10%-7.50%, 0.05%-7.50% and 1.00%-100.00% respectively, and the precision of the method for SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 range from 0.20% to 0.005%, so the method of X-ray fluorescence spectrometry is a fast and effectual method for detecting the composition of phosphate fertilizer. The contents of the above elements showed (1) the detected superphosphate content is 18.101% of P2O5, which is accordant to the labeled level (> or = 16%); (2) the detected superphosphate contains much SiO2, TFe2O3, MgO, CaO and K2O, which are necessary for plant growth and the content of which is 16.954%, 1.495%, 1.580%, 21.428% and 1.585% respectively. These data showed that phosphate fertilizer sometimes can supply some trace elements for plants, but we should eliminate the interference effect of these elements when we research the role of phosphorus; (3) superphosphate contains 3.225% of Al2O3, so the authors should attention to the aluminium poison when superphosphate is used chronically. PMID:19271522

  10. Preparation and characterizaton of CaO nanoparticle for biodiesel production

    Science.gov (United States)

    Gupta, Jharna; Agarwal, Madhu

    2016-04-01

    Nanoparticle of CaO from calcium Nitrate (CaO/CaN) and Snail shell (CaO/SS) are successfully synthesized by method as described in the literature and used as an active and stable catalyst for the biodiesel production. These catalysts are characterized by Fourier-transform infrared spectra (FT-IR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The average crystalline size in nanometer was also calculated by Debye-Scherrer equation. The performance of the CaO/CaN and CaO/SS were tested for their catalytic activity via transesterification process and it was found that biodiesel yield has been increased from 93 to 96%. The optimum conditions for the highest yield were 8wt% catalyst loading, 65°C temperature, 12:1 methanol/oil molar ratio, and 6 h for reaction time. The nano catalyst from snail shell exhibits excellent catalytic activity and stability for the transesterification reaction, which suggested that this catalyst would be potentially used as a solid base nano catalyst for biodiesel production. In order to examine the reusability of catalyst developed from snail shell, five transesterification reaction cycles were also performed.

  11. Biodiesel production from waste cooking oil using KBr impregnated CaO as catalyst

    International Nuclear Information System (INIS)

    Highlights: • KBr impregnated CaO has been used as heterogeneous catalyst. • Efficient use of waste cooking oil as feedstock. • Response Surface Methodology was used to optimize process parameters. - Abstract: This research paper deals with the synthesis of a heterogeneous catalyst (KBr/CaO) from commercial calcium oxide and potassium bromide by wet impregnation method. This solid catalyst was tested for transesterification of waste cooking oil (WCO). The synthesized catalyst was characterized by Fourier Transform Infrared spectrometry (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. Transesterification reaction parameters were varied to obtain the maximum yield of biodiesel. Response Surface Methodology (RSM) using Central Composite Design (CCD) was employed to study the effect of the process variables like methanol to oil ratio, catalyst loading and reaction time. The optimum conditions obtained using regression models were found to be 12:1 methanol: oil ratio, 3 wt% catalyst loading and 1.8 h reaction time. The composition of FAME was determined using Gas Chromatography–Mass Spectrometry (GC–MS). The performance and emission characteristics for various blends of biodiesel (B10, B20, B50 and B100) were investigated in a four stroke direct injection diesel engine. The results indicated that the brake thermal efficiency, particulate matter, unburned hydrocarbons, carbon monoxide emissions reduced with increased concentration of biodiesel in the fuel blends, whereas the specific fuel consumption, NOx emissions and exhaust gas temperature increased

  12. Vanadium extraction and dephosphorization from V-bearing hot metal with fluxes containing CaO

    Institute of Scientific and Technical Information of China (English)

    王艳南; 宋文臣; 李宏

    2015-01-01

    Extracting vanadium and removing phosphorus simultaneously by adding CaO containing materials to V-bearing hot metal were investigated under the condition of simulating the process of vanadium extraction with insufficiently supplying oxygen in converter. Through preliminary experiments, 3 h and 1375 °C were chosen as the optimum holding time and reaction temperature for formal experiments, respectively. The results of the formal experiments suggest that making basic slag can extract vanadium and remove phosphorus simultaneously. The vanadium extraction rate (ηV) and phosphorus removal rate (ηP) both increase with an increase in the basicity of the original slag materials and the Fe2O3 contents. The vanadium distribution ratio(LV¢)is about an order of magnitude greater than the phosphorus distribution ratio(LP¢),but the latter is more sensitive to slag basicity than the former. The phosphorus distribution ratio is beyond 6 when the basicity of the original slag materials is beyond 1, which indicates a much better performance of phosphorus removal compared to the phosphorus removal in the current process. Therefore, it is very feasible to properly raise slag basicity to remove phosphorus with consideration of the grade of vanadium slag. The relations betweenηV andηP, and betweenL′V andL′P are linear under the experimental conditions.

  13. Response of Stream Pollution Characteristics to Catchment Land Cover in Cao-E River Basin, China

    Institute of Scientific and Technical Information of China (English)

    SHEN Ye-Na; L(U) Jun; CHEN Ding-Jiang; SHI Yi-Ming

    2011-01-01

    This study addressed the relationship of river water pollution characteristics to land covers and human activities in the catchments in a complete river system named Cao-E River in eastcrn China. Based on the hydrogsochemical data collected monthly over a period of 3 years, cluster analysis (CA) and principal component analysis (PCA) were adopted to categorize the river reaches and reveal their pollution characteristics. According to the differences of water quality in the river reaches and land use patterns and average population densities in their catchments, the whole river system could be categorized into three groups of river reaches, i.e., non-point sources pollution reaches (NPSPR), urban reaches (UR) and mixed sources pollution reaches (MSPR). In UR and MSPR, the water quality was mainly impacted by nutrient and organic pollution, while in NPSPR nutrient pollution was the main cause. The nitrate was the main nitrogen form in NPSPR and particulate phosphorus was the main phosphorus form in MSPR. There were no apparent trends for the variations of pollutant concentrations with increasing river flows in NPSPR and MSPR, while in UR the pollutant concentrations decreased with increasing river flows. Thus dry season was the critical period for water pollution control in UR. Therefore, catchment land covers and human activities had significant impact on river reach water pollution type, nutrient forms and water quality responses to hydrological conditions, which might be crucial for developing strategies to combat water pollution in watershed scale.

  14. A Comparative Study of Female-Themed Literary Creations by Cao Pi and Cao Zhi%曹丕、曹植女性题材创作比较论

    Institute of Scientific and Technical Information of China (English)

    张竞怿

    2012-01-01

    As prominent representatives of Jian'an Literature,and influenced by the circumstances of that era,Cao Pi and Cao Zhi both have produced a series of outstanding literary works themed on females.However,owing to differences in personal experiences,character,and temperament,they have developed diverse artistic styles in their respective poetry creation.The exquisitely subtle mood,the masterly skills of expressing emotions,and the delicate and gentle nature of literati are the main characteristics of Cao Pi's poems.By contrast,the poems written by Cao Zhi feature gorgeous and refined diction,deep personal sentiments,and various remarkable descriptions of feelings,affections and attitudes.Their literatures can not only exhibit the spirit of the times,but also add creative and unique radiance to the literature world.%曹丕与曹植是建安文学的杰出代表,受时代风气的影响,都写出了一系列优秀的女性题材作品。但由于二人的经历、性格、气质有所不同,因此在这类诗歌创作中又形成了不同的艺术风格:曹丕的代言体诗委婉细腻,工于言情,多文士之气。曹植诗则多生情态,辞采华茂,经常寄予个人深沉的情感。他们的作品既有浓郁的时代气息,又放射出独特的个性光辉。

  15. Effect of MgO Additive on Volumetric Expansion of Self-Degradable Cements

    Energy Technology Data Exchange (ETDEWEB)

    Sugama T.; Warren, J.; Butcher, T.

    2011-09-30

    We identified hard-burned magnesium oxide (MgO) as a suitable expansive additive for improving the plugging performance of self-degradable, temporary sodium silicate-activated slag/Class C fly ash (SSASC) blend cement sealers into rock fractures in Enhanced Geothermal Systems (EGSs). MgO extended the volumetric expansion of sealers during their exposure to a hydrothermal environment at 200 C under pressures, ranging from 300 to 1500 psi. A great expansion ratc of 19.3% was observed by adding 3.0 wt% MgO under 300 psi pressure, thus promising to plug thoroughly inner fracture. When the pressure was increased from 300 psi to 1500 psi, the expansion rate of cement markedly reduced, corresponding to the formaLion of crack-free specimens and the improvement of compressive strength. However, with 3.0 wt% MgO, the specimens still engendered the generation of numerous visual cracks, although they were prepared under a high pressure of 1500 psi. The effective content of MgO in minimizing and eliminating the generation of cracks was 2.0 wt%, which provided a moderate expansion of {ge} 0.5%. The compressive strength of 2.0 wt% MgO specimens made under a pressure of 300 psi rose {approx} 1.7-fold to 4816 psi with an increasing pressure to 1500 psi. The in-situ growth of brucite crystal formed by the hydrothermal hydration of MgO was responsive for such an expansion of the SSASC cement; meanwhile. two crystalline hydrothermal reaction products, 1.1 nm tobermorite and calcium silicate hydrated, contributed to the development of the sealer's compressive strength. Thus, the increasing pressure seems to suppress and control a growth rate of brucite crystal in response to a lower extension of expansion. Furthermore, all MgO-conlaining SSASC sealers possessed the water-catalyzed self-degradable properties.

  16. Low-temperature atomic layer deposition of MgO thin films on Si

    International Nuclear Information System (INIS)

    Magnesium oxide (MgO) films have been grown by atomic layer deposition in the wide deposition temperature window of 80–350 °C by using bis(cyclopentadienyl)magnesium and H2O precursors. MgO thin films are deposited on both HF-last Si(1 0 0) and SiO2/Si substrates at a constant growth rate of ∼0.12 nm cycle−1. The structural, morphological and chemical properties of the synthesized MgO thin films are investigated by x-ray reflectivity, grazing incidence x-ray diffraction, time-of-flight secondary ion mass spectrometry and atomic force microscopy measurements. MgO layers are characterized by sharp interface with the substrate and limited surface roughness, besides good chemical uniformity and polycrystalline structure for thickness above 7 nm. C–V measurements performed on Al/MgO/Si MOS capacitors, with MgO in the 4.6–11 nm thickness range, allow determining a dielectric constant (κ) ∼ 11. Co layers are grown by chemical vapour deposition in direct contact with MgO without vacuum-break (base pressure 10−5–10−6 Pa). The as-grown Co/MgO stacks show sharp interfaces and no elements interdiffusion among layers. C–V and I–V measurements have been conducted on Co/MgO/Si MOS capacitors. The dielectric properties of MgO are not influenced by the further process of Co deposition. (paper)

  17. The effect of microstructure and crystal defect on electrochemical performances of MgO nanobelts

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • MgO nanobelts were prepared by DC arc plasma jet CVD. • Growth time for nanobelts in synthesizing does not exceed 5 min. • Nanobelts exhibit high sensitivity in the selective determination of diphenols. • Crystal defects have been confirmed by HRTEM, FT-IR, PL and TGA. • Electrocatalytic properties were correlated with the presence of surface defects. - Abstract: The electrochemical properties of one-dimensional (1-D) nanomaterials are highly sensitive to their surface microstructure and crystal defects. MgO nanobelts were obtained by magnesium nitrate decomposition using the direct arc plasma jet chemical vapor deposition technique, with a molybdenum substrate at 950 °C for 5 min. The structural details, defects, and electrochemical properties of MgO nanobelts were determined. From high-resolution transmission electron microscopy, the nanobelts contain numerous contacts, rough edges, vacancies, and doping defects. Nanobelts with large surface area and oxide ions in low coordination (with O5C2− and O4C2−, for terrace and edge sites, and O3C2− for corner and kink sites) were seen by various analytical studies. The electrochemical performances of the MgO nanobelts-modified electrode were investigated using standard techniques. The unique nanostructural features and crystal defects endow MgO nanobelt with excellent electrochemical performance as demonstrated in their application in the selective determination of hydroquinone (HQ) and catechol (CC); both can be oxidized at the MgO nanobelt-modified electrode. This nanomaterial allows the sensitive determination of HQ and CC without cross-interference. The MgO nanobelts/glassy-carbon electrode exhibited high sensitivity in the selective determination of HQ and CC, with detection limits of 1 × 10−8 M

  18. Origin and geochemistry of Pan-African granitoid rocks in the Gabal Um Shomer area, Southwestern Sinai, Egypt

    Institute of Scientific and Technical Information of China (English)

    E1-Tokhi M.M.; Musallum A.; Amin B.M.

    2009-01-01

    Geological, petrological and geochemical studies indicated that there are two distinct types of granitoid rocks: older quartz diorites to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a meta-aluminous chemistry and a calc-alkaline character, with high MgO, Fe2O3, TiO2, CaO, P2O5, Sr and low SiO2, K2O, and Rb. Their major and trace elements data, together with low 87Sr/ 86Sr ratios (0.7029±0.0008) are indicative of I-type affinities. The second- and third-phase granitoids range from calc-alkaline to alkaline, respectively. The second-phase granitoids have a peraluminous chemistry and high Sr, Ba, CaO, MgO, Al2O3 and Ti2O and low SiO2, K2O, Nb, Y and Rb relative to the third-phase granitoids. The corundum normative nature and field observations suggested that it was formed by partial melting of the lower crust. The third-phase granitoids are alkaline in nature and characterized by higher SiO2, Rb, Y, Nb and lower MgO, Sr and Ba values than the younger granitoids (phase II). They are A-type granitoids which were generated from below or within the existing continental crust.

  19. Characterisation of the mgo operon in Pseudomonas syringae pv. syringae UMAF0158 that is required for mangotoxin production

    Directory of Open Access Journals (Sweden)

    Arrebola Eva

    2012-01-01

    Full Text Available Abstract Background Mangotoxin is an antimetabolite toxin that is produced by strains of Pseudomonas syringae pv. syringae; mangotoxin-producing strains are primarily isolated from mango tissues with symptoms of bacterial apical necrosis. The toxin is an oligopeptide that inhibits ornithine N-acetyl transferase (OAT, a key enzyme in the biosynthetic pathway of the essential amino acids ornithine and arginine. The involvement of a putative nonribosomal peptide synthetase gene (mgoA in mangotoxin production and virulence has been reported. Results In the present study, we performed a RT-PCR analysis, insertional inactivation mutagenesis, a promoter expression analysis and terminator localisation to study the gene cluster containing the mgoA gene. Additionally, we evaluated the importance of mgoC, mgoA and mgoD in mangotoxin production. A sequence analysis revealed an operon-like organisation. A promoter sequence was located upstream of the mgoB gene and was found to drive lacZ transcription. Two terminators were located downstream of the mgoD gene. RT-PCR experiments indicated that the four genes (mgoBCAD constitute a transcriptional unit. This operon is similar in genetic organisation to those in the three other P. syringae pathovars for which complete genomes are available (P. syringae pv. syringae B728a, P. syringae pv. tomato DC3000 and P. syringae pv. phaseolicola 1448A. Interestingly, none of these three reference strains is capable of producing mangotoxin. Additionally, extract complementation resulted in a recovery of mangotoxin production when the defective mutant was complemented with wild-type extracts. Conclusions The results of this study confirm that mgoB, mgoC, mgoA and mgoD function as a transcriptional unit and operon. While this operon is composed of four genes, only the last three are directly involved in mangotoxin production.

  20. Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete

    OpenAIRE

    Mo Jinchuan; Ou Zhongwen; Wang Yahui

    2016-01-01

    The reactive powder concrete (RPC) was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF) on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM) and drying shrinkage test. Results indi...

  1. Thermogravimetric study of chemical compatibility of graphite with metal oxides

    International Nuclear Information System (INIS)

    Graphite and graphite mixtures with metal oxides are studied in conditions of nonisothermal heating to 1000 deg C using the methods of thermodynamic and gravimetric analyses. Chemical compatibility of graphite with Al2O3, CaO, SiO2, MgO, Fe2O3, TiO2, Na2O, K2O in the compositions considered is established. A decrease in the sample mass observed on the gravimetric curves in the presence of admixtures does not exceed the same value in pure graphite samples in specified conditions

  2. Statistical analysis of the effective factors on the 28 days compressive strength and setting time of the concrete

    OpenAIRE

    Bahador Abolpour; Mohammad Mehdi Afsahi; Saeed Gharib Hosseini

    2015-01-01

    In this study, the effects of various factors (weight fraction of the SiO2, Al2O3, Fe2O3, Na2O, K2O, CaO, MgO, Cl, SO3, and the Blaine of the cement particles) on the concrete compressive strength and also initial setting time have been investigated. Compressive strength and setting time tests have been carried out based on DIN standards in this study. Interactions of these factors have been obtained by the use of analysis of variance and regression equations of these factors have been obtain...

  3. Statistical analysis of the effective factors on the 28 days compressive strength and setting time of the concrete

    OpenAIRE

    Abolpour, Bahador; Mehdi Afsahi, Mohammad; Hosseini, Saeed Gharib

    2014-01-01

    In this study, the effects of various factors (weight fraction of the SiO2, Al2O3, Fe2O3, Na2O, K2O, CaO, MgO, Cl, SO3, and the Blaine of the cement particles) on the concrete compressive strength and also initial setting time have been investigated. Compressive strength and setting time tests have been carried out based on DIN standards in this study. Interactions of these factors have been obtained by the use of analysis of variance and regression equations of these factors have been obtain...

  4. Fabrication and performance testing of CaO insulator coatings on V-5%Cr-5%Ti in liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Dragel, G. [Argonne National Lab., Chicago, IL (United States)

    1995-04-01

    Corrosion resistance of structural materials, and the magnetohydrodynamic (MHD) force and its influence on thermal hydraulics and corrosion, are major concerns in the design of liquid-metal blankets for magnetic fusion reactors (MFRs). The objective of this study is to develop in-situ stable coatings at the liquid-metal/structural-material interface, with emphasis on coatings that can be converted to an electrically insulating film to prevent adverse currents that are generated by the MHD force from passing through the structural walls. The electrical resistance of CaO coatings produced on V-5Cr-5Ti by exposure of the alloy to liquid Li that contained 0.5 - 8.5 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degree}C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420{degree}C to produce a CaO coating.

  5. Use of heterogeneous CaO and SnO2 catalysts supported on rice husk ash to produce biodiesel

    International Nuclear Information System (INIS)

    Silica obtained from rice husk after acid leaching and calcination was compared to commercial silica as a catalyst support. CaO and SnO2 catalysts were prepared by impregnation and tested in the transesterification of soybean oil and the esterification of oleic acid. CaO catalysts showed basic character and were the most active for transesterification, whereas SnO2 catalysts were acid and the most effective for esterification. In both cases the performances of the catalysts prepared with rice husk ash and commercial silica were similar. These results demonstrate that rice husk is a cost-effective and environmentally-friendly source of silica that can be used as a catalyst support. (author)

  6. Influences of arc current on composition and properties of MgO thin films prepared by cathodic vacuum arc deposition

    International Nuclear Information System (INIS)

    MgO thin films with high optical transmittances (more than 90%) were prepared by cathodic vacuum arc deposition technique. With the increase of arc current from 40 to 80 A, the deposition pressure decreases and the film thickness increases; the atomic ratio of Mg/O in MgO thin films (obtained by RBS) increases from 0.97 to 1.17, giving that deposited at 50 A most close to the stoichiometric composition of the bulk MgO; the grains of MgO thin films grow gradually as shown in SEM images. XRD patterns show that MgO (1 1 0) orientation is predominant for films prepared at the arc currents ranged from 50 to 70 A. The MgO (1 0 0) orientation is much enhanced and comparable to that of MgO (1 1 0) for films prepared at the arc current of 80 A. The secondary electron emission coefficient of MgO thin film increases with arc current ranged from 50 to 70 A.

  7. Bonding trends and dimensionality crossover of gold nanoclusters on metal-supported MgO thin films

    OpenAIRE

    Ricci, D; Bongiorno, A.; Pacchioni, G.; Landman, U.

    2006-01-01

    Bonding of gold clusters, Aun n 8, 16, and 20, on MgO(100) and on thin MgO films supported on Mo(100) is investigated using first-principles density-functional theory. Enhanced adhesive bonding is found for clusters deposited on metal-supported MgO films of thickness up to about 1 nm, or 4 to 5 MgO layers, originating from electrostatic interaction between the underlying metal and metal-induced excess electronic charge accumulated at the cluster interface with the oxide film. The i...

  8. Pengaruh Lama Reaksi Terhadap Perubahan Karakteristik Biodiesel Turunan Minyak Kemiri Dengan Menggunakan Katalis CaO Dan Kosolvent Eter

    OpenAIRE

    Jannu, Henri

    2010-01-01

    It has been done the manufacturing of biodiesel candlenut oil through transesterification process. This process was conducted in the autoclave with candlenut oil mixture : methanol 1:12 mol. CaO catalyst was 8% of oil weight and it used cosolvent ether 200 ml. This reaction lasted at the temperature 650°C with variation of time for 1 hour, 2 hours, and 3 hours. The transesterifiction produced two levels, namely top level containing metal ester (FAME) and down level ...

  9. Preparation, characterization and photocatalytic activity of Bi2O3-MgO composites

    International Nuclear Information System (INIS)

    A series of Bi2O3-MgO composites were synthesized by solvent-thermal method. It was found that the Bi2O3-MgO composites perform much better than TiO2 (P25), Bi2O3 and MgO in the photocatalytic degradation of rhodamine B (RhB) in the presence of HCl and under irradiation of visible light (λ > 400 nm). The effects of Bi/Mg molar ratio, crystallization temperature of Bi2O3-MgO and reaction conditions on photocatalytic activity were studied. The best performance was observed over the composite with Bi:Mg molar ratio equal to 2:1 that had been subject to crystallization at 120 deg. C for 20 h. In addition, the photocatalytic efficiency of the composite can be significantly enhanced by the presence of hydrochloric acid. The prepared samples were characterized by XRD and UV-vis DRS techniques. The relationships between the structure and photocatalytic performance of the as-prepared Bi2O3-MgO samples were also investigated.

  10. Current progress in YBCO coated conductors using IBAD MgO template layers

    Energy Technology Data Exchange (ETDEWEB)

    Groves, J. R. (James R.); Arendt, P. N. (Paul N.); Foltyn, S. R. (Stephen R.); Jia, Quanxi; Holesinger, T. G. (Terry G.); Emmert, L. A. (Luke A.); DePaula, R. F. (Raymond Felix); Dowden, P. C. (Paul C.); Stan, L. (Liliana); Brewer, R. T. (Rhett T.); Atwater, H. A. (Harry A.)

    2002-01-01

    We present key improvements to growing high quality ({approx}7 degrees {Delta}{phi}) magnesium oxide (MgO) The use of a new layer for IBAD MgO nucleation and reduction in surface roughness of substrates have resulted in better in-plane texture. The processing window for obtaining optimum template texture is very narrow ({approx}10 seconds) using Si,N,. This has been ameliorated by use of an alternate amorphous nucleation layer. The substrate surface roughness has a significant effect on the initial nucleation texture of IBAD MgO films. A surface roughness of -1 nm has resulted in better in-plane texture for IBAD MgO films deposited on metal substrates. We have also implemented a method to quantify IBAD MgO texture using reflected high-energy electron diffraction (RHEED). Utilizing this in situ tool, we have been able to refine deposition parameters to routinely grow films in batch mode that have a {Delta}{phi} of {approx} 7 degrees. Deposited meter lengths have had {Delta}{phi} values from 7-9 degrees with 10% uniformity. One to two micrometer thick YBCO films on these templates have had critical current densities in excess of 1 MA/cm2 at 75 K, in self field.

  11. Ageing and vapor chopping effect on the properties of MgO thin films

    International Nuclear Information System (INIS)

    Highlights: • Air exposure ageing effect on the basic properties of MgO thin film is studied. • Vapor chopping technique is used to modify the properties of MgO thin films. • Ageing inhibits due to thin film’s quality improvement by vapor chopping. • Vapor chopped films show better device performance than non-chopped thin films. -- Abstract: Nanoscale magnesium oxide thin films have been prepared on glass substrates by thermal oxidation (in air) of vacuum evaporated magnesium films. The ageing (air exposure) effect for 1, 10, 20 and 30 days on the various properties of MgO thin films was studied. The ageing effect on the optoelectronic devices i.e. optical waveguide and plasma display panel’s performance was examined by measuring their optical transmission loss and secondary electron emission yield, respectively. Vapor chopping technique was employed for thin film quality improvement followed by ageing inhibition. The firing voltage for fresh vapor chopped (VC) MgO thin films was in 125–150 V range, which shifted to 140–178 V after 30 days, whereas in the non-chopped (NC) films it increased up to 165–210 V from 140–160 V. After 30 days ageing, NC thin film surface morphology changed from polished to dull due to wrapped moisture like layer, whereas VC thin film morphology was unpretentious. The XPS analysis also confirmed the VC MgO thin films superior sustainability against the ageing than NC films

  12. Electron irradiation damage and color centers of MgO nanocube

    International Nuclear Information System (INIS)

    Magnesium oxide (MgO) has been of interest for several decades as a promising tunable broadband laser due to its vacancy defects (color centers). In this work we introduced color centers into MgO nanocube by electron irradiation in a transmission electron microscope (TEM). Square nano-holes were formed from the electron-exit face using 100 and 300 keV electrons, and a broad O-vacancy (color-center) absorption peak around 4.1–6.6 eV was observed by valence-electron energy-loss spectroscopy (VEELS). We investigated the mechanism of MgO damage by high-energy electron beams. The hole formation is believed to involve a mixed removal of diatomic MgO molecules as well as Mg and O species in stoichiometric proportion. Observations using high-resolution transmission electron microscopy (HRTEM) and VEELS suggest that bulk O-vacancies are generated near the electron-exit face, due to the forward momentum transferred from fast-electron collisions and the Coulomb attraction of negative O-ions by the positively charged MgO surface

  13. Atomic layer deposition of MgO films on yttria-stabilized zirconia microtubes

    International Nuclear Information System (INIS)

    Deposition of MgO thin film on nanocrystalline yttria-stabilized zirconia microtubes was investigated. The microtubes were prepared by self-formation from threads drawn directly from zirconium butoxide [Zr(OBu)4] precursor and heat treated at 800 °C. The tubes possessed 100% tetragonal phase, their typical outer diameter was 50 μm, inner diameter 30 μm and length 1 cm. MgO films were deposited from β-diketonate-type precursor 2,2,6,6-tetramethyl-heptanedionato-3,5-magnesium(II) at 220 °C by atomic layer deposition. Thickness of MgO film on microtubes was 15.8 nm and growth rate 0.105 Å/cycle. - Highlights: • MgO films were deposited on the surface of yttria-stabilized zirconia microtubes. • The studies are carried out on the basis of surface modification of microtubes. • Films were deposited from β-diketonate-type precursor Mg(thd)2. • The growth temperature of MgO film was 220 °C

  14. Growth of textured MgO through e-beam evaporation and inclined substrate deposition

    International Nuclear Information System (INIS)

    Long length textured MgO template on Hastelloy C276(TM) (HC) has been successfully deposited in a reel-to-reel (R2R) electron beam (e-beam) evaporation system by inclined substrate deposition (ISD). High deposition rate up to 10 nm s-1 with exposure length of 7 cm has been realized. The MgO template showed good in-plane texture of 9.5 deg. -11.5 deg. measured from the (002) phi scans. Experimental results reveal that MgO in-plane texture is formed by the preferred growth direction of [11n] parallel substrate normal and one of the MgO {200} planes rotates to the in-flux direction. A new expression, termed the 'two-thirds relationship', between the inclination angle α and the tilted angle of the (00l) plane from the substrate normal, β, has been summarized. YBa2Cu3O7-δ (YBCO) film deposited by pulsed laser deposition (PLD) on strontium ruthenate (SRO) buffered ISD MgO showed Tc of 91 K with transition width of 1 K. Critical current measurement indicated an Ic of 110 A cm-1 at 77 K in self-field for 0.68 μm YBCO film, corresponding to a Jc of 1.6 MA cm-2

  15. Growth of textured MgO through e-beam evaporation and inclined substrate deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y [Materials Research Lab, UES Inc. Dayton, OH 45432 (United States); Lei, C H [Department of MSE, University of Illinois, Urbana, IL 61801 (United States); Ma, B [Argonne National Laboratory, Argonne, IL 60439 (United States); Evans, H [Materials Research Lab, UES Inc. Dayton, OH 45432 (United States); Efstathiadis, H [Albany Nanotech, Albany, NY 12203 (United States); Manisha, R [Albany Nanotech, Albany, NY 12203 (United States); Massey, M [Materials Research Lab, UES Inc. Dayton, OH 45432 (United States); Balachandran, U [Argonne National Laboratory, Argonne, IL 60439 (United States); Bhattacharya, R [Materials Research Lab, UES Inc. Dayton, OH 45432 (United States)

    2006-08-15

    Long length textured MgO template on Hastelloy C276(TM) (HC) has been successfully deposited in a reel-to-reel (R2R) electron beam (e-beam) evaporation system by inclined substrate deposition (ISD). High deposition rate up to 10 nm s{sup -1} with exposure length of 7 cm has been realized. The MgO template showed good in-plane texture of 9.5 deg. -11.5 deg. measured from the (002) phi scans. Experimental results reveal that MgO in-plane texture is formed by the preferred growth direction of [11n] parallel substrate normal and one of the MgO {l_brace}200{r_brace} planes rotates to the in-flux direction. A new expression, termed the 'two-thirds relationship', between the inclination angle {alpha} and the tilted angle of the (00l) plane from the substrate normal, {beta}, has been summarized. YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) film deposited by pulsed laser deposition (PLD) on strontium ruthenate (SRO) buffered ISD MgO showed T{sub c} of 91 K with transition width of 1 K. Critical current measurement indicated an I{sub c} of 110 A cm{sup -1} at 77 K in self-field for 0.68 {mu}m YBCO film, corresponding to a J{sub c} of 1.6 MA cm{sup -2}.

  16. Growth of textured MgO through e-beam evaporation and inclined substrate deposition

    Science.gov (United States)

    Xu, Y.; Lei, C. H.; Ma, B.; Evans, H.; Efstathiadis, H.; Manisha, R.; Massey, M.; Balachandran, U.; Bhattacharya, R.

    2006-08-01

    Long length textured MgO template on Hastelloy C276™ (HC) has been successfully deposited in a reel-to-reel (R2R) electron beam (e-beam) evaporation system by inclined substrate deposition (ISD). High deposition rate up to 10 nm s-1 with exposure length of 7 cm has been realized. The MgO template showed good in-plane texture of 9.5°-11.5° measured from the (002) phi scans. Experimental results reveal that MgO in-plane texture is formed by the preferred growth direction of [11n]\\parallel \\mathrm {substrate} normal and one of the MgO {200} planes rotates to the in-flux direction. A new expression, termed the 'two-thirds relationship', between the inclination angle α and the tilted angle of the (00l) plane from the substrate normal, β, has been summarized. YBa2Cu3O7-δ (YBCO) film deposited by pulsed laser deposition (PLD) on strontium ruthenate (SRO) buffered ISD MgO showed Tc of 91 K with transition width of 1 K. Critical current measurement indicated an Ic of 110 A cm-1 at 77 K in self-field for 0.68 µm YBCO film, corresponding to a Jc of 1.6 MA cm-2.

  17. Relationship between catchment characteristics and forms of nitrogen in Cao-E River Basin, Eastern China

    Institute of Scientific and Technical Information of China (English)

    JIN Shuquan; LU Jun; CHEN Dingjiang; SHEN Yena; SHI Yiming

    2009-01-01

    The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types including headwater in mountainous areas (type I), agricultural non-point source (NPS) pollution in rural areas (type II), municipal and industrial pollution in urban areas (type III), and combined pollution in the main stream (type IV). Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River basin in Zhejiang, Eastern China. The concentrations of NO3-N, NH4+-N, and total nitrogen (TN) were measured. The mean concentrations of NO3-N were in the order type IV > type II> type III > type I, whereas, NH4+-N, total organic nitrogen (TON), and TN were in the order type III > type IV > type II> type I. In headwater and rural reaches, CNO3-N was much higher than CNH4+-N. In urban reaches, TON and NH4+-N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, CNH4+-N decrease with increasing distance from cities, and CNO3-N increased with the increasing area of farmland in the catchments. With increased river flow, the CNO3-N increased and the CNH4+-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.

  18. Using CaO- and MgO-rich industrial waste streams for carbon sequestration

    International Nuclear Information System (INIS)

    To prevent rapid climate change, it will be necessary to reduce net anthropogenic CO2 emissions drastically. This likely will require imposition of a tax or tradable permit scheme that creates a subsidy for negative emissions. Here, we examine possible niche markets in the cement and steel industries where it is possible to generate a limited supply of negative emissions (carbon storage or sequestration) cost-effectively. Ca(OH)2 and CaO from steel slag or concrete waste can be dissolved in water and reacted with CO2 in ambient air to capture and store carbon safely and permanently in the form of stable carbonate minerals (CaCO3). The kinetics of Ca dissolution for various particle size fractions of ground steel slag and concrete were measured in batch experiments. The majority of available Ca was found to dissolve on a time scale of hours, which was taken to be sufficiently fast for use in an industrial process. An overview of the management options for steel slag and concrete waste is presented, which indicates how their use for carbon sequestration might be integrated into existing industrial processes. Use of the materials in a carbon sequestration scheme does not preclude subsequent use and is likely to add value by removing the undesirable qualities of water absorption and expansion from the products. Finally, an example scheme is presented which could be built and operated with current technology to sequester CO2 with steel slag or concrete waste. Numerical models and simple calculations are used to establish the feasibility and estimate the operating parameters of the scheme. The operating cost is estimated to be US$8/t-CO2 sequestered. The scheme would be important as an early application of technology for capturing CO2 directly from ambient air

  19. Fabrication of STO buffer films on MgO substrates by the MOD method

    International Nuclear Information System (INIS)

    We fabricated SrTiO3 (STO) thin films, which are expected to be used as buffer layers on MgO substrates, by the metal-organic decomposition (MOD) method, and evaluated the properties of the films. By introducing a 2-step heat treatment and optimizing the precursor temperature, we could improve the full width at half maximum (FWHM) values of the rocking curves up to 1.81 deg in the X-ray diffraction (XRD) measurements of the STO films on MgO substrates. The minimum FWMH value of the in-plane rocking curves of the films was 2.60 deg and the films had a cube-on-cube structure on the MgO substrates. Furthermore, the root mean square (rms) roughness values of the surfaces of the STO thin films derived from atomic force microscopy (AFM) were 2.11-5.37 nm

  20. Structure and properties of ZrO2-MgO powders

    Science.gov (United States)

    Buyakova, S. P.; Kalatur, E. S.; Buyakov, A. S.; Kulkov, S. S.

    2016-04-01

    It have been studied magnesia stabilized zirconia (ZrO2-MgO) powders produced by high-frequency decomposition of water salt solutions. It have been shown that due to precursor dissociation powders consist of spherical particles with smooth surface and irregular hollow aggregates resembling foam. An increase in the magnesium concentration in the precursor has an effect on the powder properties, namely, the specific surface decreases significantly and the bulk density increases. Zirconia in the nanostructured state is present only in the powders with 8.6 and 13.9 mole% MgO, with the size of the c-ZrO2 crystallites in them no more than 100 nm. In powder with 43.3 mole% of MgO the magnesia content in c-ZrO2 solid solution corresponds to its solubility limit of 22.2 mole% at temperature 2100°C.

  1. Multi-particle assembled porous nanostructured MgO: its application in fluoride removal

    International Nuclear Information System (INIS)

    In this article, a simple and economical route based on ethylene glycol mediated process was developed to synthesize one-dimensional (1D) multiparticle assembled nanostructured MgO using magnesium acetate and urea as reactants. Porous multiparticle chain-like MgO has been synthesized by the calcination of a solvothermally derived single nanostructured precursor. The prepared products were characterized by an x-ray diffraction (XRD) pattern, thermogravimetry, scanning/transmission electron microscopy (SEM/TEM) and N2 adsorption (BET). As a proof of concept, the porous multiparticle chain-like MgO has been applied in a water treatment for isolated and rural communities, and it has exhibited an excellent adsorption capability to remove fluoride in waste water. In addition, this method could be generalized to prepare other 1D nanostructures with great potential for various attractive applications. (paper)

  2. INFLUENCE OF MgO ON MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF RAW CLAY FROM BURKINA FASO

    Directory of Open Access Journals (Sweden)

    MOHAMED SEYNOU

    2014-05-01

    Full Text Available The influence of MgO on mechanical and microstructural properties of raw clay material from Burkina Faso was investigated by means of X-ray diffraction, scanning electron microscopy, infrared spectroscopy, differential thermal analysis and numerical simulation. The mineralogical composition was modified with the formation of new crystalline phases such as mullite, spinel – Mg, enstatite and forsterite. During the sintering and with add of MgO, the mullite quantity decrease contrary to forsterite and affect the different properties of sintered products. The mechanical properties were improved with MgO amount around 2 – 5 wt%. For magnesia amount higher than 5 wt%, the magnesia is not entirely consumed and is originated to the formation of pores in the manufactured products which are detrimental to the mechanical properties.

  3. Study of phase transition and cohesive energy in MgO

    Science.gov (United States)

    Munjal, N.; Bhambhani, P.; Sharma, G.; Vyas, V.; Sharma, B. K.

    2012-07-01

    In this paper, we present first-principles study of phase transition and cohesive energy of MgO. The calculations are performed on the basis of density functional theory (DFT) based on linear combination of atomic orbitals (LCAO) method. In the present calculations, the generalized gradient approximation (GGA) proposed by Perdew-Burke- Ernzerhof (PBE) and Becke's scheme are considered to treat the correlation and exchange effects respectively. The study reveals that the stable phase of MgO is B1. The study also suggests B1 to B2 phase transition at 260.75 GPa and 10.98 eV cohesive energy of MgO in the stable phase. The calculated data are found in good agreement with the previous theoretical and experimental investigations.

  4. El amor en la literatura china : Una aproximación al Sueño en el pabellón rojo, de Cao Xueqin

    OpenAIRE

    Priego Casanova, Luis

    2012-01-01

    Análisis del tratamiento del amor en la novela Sueño en el Pabellón Rojo, de Cao Xueqin (dinastía Qing). Descripción del concepto de amor y emociones en la cultura china y su tradición literaria a través del argumento y las relaciones personales entre los personajes de la obra de Cao Xueqin.

  5. Thickness dependent magnetic transitions in pristine MgO and ZnO sputtered thin films

    Directory of Open Access Journals (Sweden)

    Mukes Kapilashrami

    2010-09-01

    Full Text Available We report a systematic study of the thickness dependency of room temperature ferromagnetism in pristine MgO (~100–500 nm and ZnO (~100–1000 nm thin films deposited by reactive magnetron sputtering technique under the respective identical controlled optimum oxygen ambience. As far as we know this is the first such report on ferromagnetic pure MgO thin films, a result which should be of significance in understanding the functional aspects of magnetic tunnelling characteristics in devices using MgO dielectrics. From the magnetic characterization we observe a distinct variation in the saturation magnetization (MS with increasing film thickness. In the case of MgO thin films MS values vary in the range 0.04–1.58 emu/g (i.e. 0.0012–0.046 μB/unit cell with increasing film thickness showing the highest MS value for the 170 nm thick film. Above this thickness MS is found to decrease and eventually above 420 nm the films show a paramagnetic behaviour followed by the well known diamagnetic property for the bulk (>500 nm. It is obvious that since initially the MS values increase with thickness, there has to be a maximum before the films become diamagnetic at some finite thickness. We also note that the MS values observed for MgO are the highest (more than twice the value observed for ZnO to be reported for such a defect induced ferromagnetism in a pristine oxide. The origin of ferromagnetic order in both the oxides appears to arise from the respective cat-ion vacancies. The discovery of film thickness dependent ferromagnetic order should be very useful in developing multifunctional devices based on the technologically important materials MgO and ZnO.

  6. Experimental determination of the liquidus of the binary system (Cu2O + CaO) in air at temperature from (1050 to 1500) °C

    International Nuclear Information System (INIS)

    Highlights: • Liquidus of system (Cu2O + CaO) is experimentally quantified up to 1500 °C in air. • The equilibration/quench/analysis technique is used for the first time. • CaO solubility in liquid phase is specifically quantified. - Abstract: The liquidus of the binary system (Cu2O + CaO) has been experimentally investigated over the temperature range from (1050 to 1500) °C in air. The liquidus has been quantified by the equilibration/quench/analysis technique. Equilibrated specimens were quenched in brine solution of 10 wt% NaCl. Specimens were then examined by Energy-Dispersive X-ray Spectroscopy (EDS) and Electron probe micro-analyzer (EPMA) to quantify liquid chemical compositions. This work reveals that the solubility of CaO in the liquid phase of the binary (Cu2O + CaO) at higher temperatures is lower than previously reported, and the deviation systematically increases with a corresponding increase in temperature. This is predominant at temperatures between (1300 and 1500) °C where a deviation of up to 5 wt% in CaO solubility is observed. The solubility of Cu2O in liquid phase for the cuprite saturated section of the binary however is consistent with all the previous authors

  7. Intrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    Directory of Open Access Journals (Sweden)

    D. Kadri

    2005-01-01

    Full Text Available The Thermoluminescence (TL properties of an MgO single crystal sample were studied from 170 to 500°K after UV-irradiation (4.8 eV for 10 min. The aim of this study was to determine the MgO intrinsic defects centers and in particular the F, F+, F2 and Fcat centers, these defects are localized in the 270-570 nm region, their TL signal was characterized by four emission bands detected at wavelengths 540, 380, 350 and 290 nm, respectively.

  8. Intrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    OpenAIRE

    D. Kadri; A. Mokeddem; Hamzaoui, S.

    2005-01-01

    The Thermoluminescence (TL) properties of an MgO single crystal sample were studied from 170 to 500°K after UV-irradiation (4.8 eV for 10 min). The aim of this study was to determine the MgO intrinsic defects centers and in particular the F, F+, F2 and Fcat centers, these defects are localized in the 270-570 nm region, their TL signal was characterized by four emission bands detected at wavelengths 540, 380, 350 and 290 nm, respectively.

  9. Preparation and characterization of the ZrO2: MgO ceramic compound

    International Nuclear Information System (INIS)

    Zirconium oxide (ZrO2); magnesium oxide (MgO) and zirconia-magnesia (ZrO2: MgO) ceramic specimens have been prepared by the precipitation and coprecipitation chemical methods. Some of the process parameters, pH and temperature, have been studied. The qualitative as well as the quantitative results are in good agreement with the results reported in scientific journals. The details of the experimental procedures and the phase analysis of the calcined samples will be described. (author)

  10. Oxygen vacancy enhanced room temperature ferromagnetism in Al-doped MgO nanoparticles

    OpenAIRE

    Mishra, Debabrata; Mandal, Balaji P.; Mukherjee, Rupam; Naik, Ratna; Lawes, Gavin; Nadgorny, Boris

    2012-01-01

    We have investigated the room temperature ferromagnetic order that develops in Al-substituted magnesium oxide, Mg(Al)O, nanoparticles with Al fractions of up to 5 at.%. All samples, including undoped MgO nanoparticles, exhibit room temperature ferromagnetism, with the saturation magnetization reaching a maximum of 0.023 emu/g at 2 at.% of Al. X-ray photoelectron spectroscopy identifies the presence of oxygen vacancies in both doped and undoped MgO nanoparticles, with the vacancy concentration...

  11. Structures and bonding characters of (MgO)3n (n = 2–8) clusters

    International Nuclear Information System (INIS)

    The chemical bonds in clusters may be different to those in the conventional bulk. Bulk magnesium oxide (MgO) is a well-known ionic material with the rocksalt structure. However, the bonding characters of MgO clusters are not clear. (MgO)3n are the magic-size clusters. The rocksalt structure and the hexagonal tube are two basic structural patterns. For large MgO clusters, the rocksalt structures are the most stable, but for small clusters, the hexagonal tubes are preferable in energy. It was suggested that the orbitals of oxygen in the hexagonal tubes hybrid in sp2 and the Mg–O bonds possess considerable covalent characters, and the orbital interaction favours the hexagonal tubes. We investigate the geometric and electronic structures of (MgO)3n (n = 2–8) clusters by ab initio methods. For n = 2–5, the n-stacked hexagonal rings and the 2 × 3 × n rocksalt isomers have the same topological structure and the hexagonal tube is lower in energy. For n = 6 and 8, the rocksalt structures change to 3 × 3 × 4 and 3 × 4 × 4 layers respectively, and they become the most stable configurations. The AIM (atoms in molecules) and NBO (natural bond orbital) analyses show the charge transfer from Mg to O is around 1.78e and 1.52e respectively, which means strongly ionic bonds in MgO clusters. The large charge transfer pushes up the 2p levels drastically in oxygen anions and the wide energy gap hinders the hybridization between the 2s and 2p orbitals of oxygen. In both the rocksalt structures and the hexagonal tubes, the overlap compositions between Mg 3s and O 2p are almost the same, and they do not vary obviously with the cluster size. For small MgO clusters, while there are more Mg–O bonds in the rocksalt structures, the average bond lengths are shorter in the hexagonal tubes, which can compensate for the smaller number of the bonds. For (MgO)18,24, many more Mg–O bonds form in the rocksalt structures, and this makes the rocksalt structures preferable to the

  12. Preparation of nanocrystalline MgO by surfactant assisted precipitation method

    International Nuclear Information System (INIS)

    Highlights: → Nanocrystalline magnesium oxide with high surface area. → MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. → MgO prepared with surfactant showed a plate-like shape. → Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH)2 crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH)2 nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time increased the specific surface area of

  13. Tailoring Interlayer Exchange Coupling of Ferromagnetic Films Across MgO with Fe Nanoclusters

    OpenAIRE

    Wong, Jared J. I.; Ramirez, Luciana; Swartz, A. G.; HOFF A.; Han, Wei; LI Yan; Kawakami, R. K.

    2010-01-01

    We investigate the interlayer exchange coupling in Fe/MgO/Fe and Fe/MgO/Co systems with magnetic Fe nanoclusters embedded in the MgO spacer. Samples are grown by molecular beam epitaxy (MBE) and utilize wedged MgO films to independently vary the film thickness and the position of the Fe nanoclusters. Depending on the position of the Fe nanoclusters, the bilinear coupling (J1) exhibits strong variations in magnitude and can even switch between antiferromagnetic and ferromagnetic. This effect i...

  14. Low-pressure Environmental TEM (ETEM) studies of Au assisted MgO nanorod growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum;

    2012-01-01

    Over the past few decades, there has been an increasing interest in the use of supported nanoparticles in applications ranging from drug delivery to catalysis. The functionality of such nanoparticles is to a large extent controlled by their shape and exposed surface facets. However, information...... 300keV electron beam with a residual pressure of 10-6mbar and a current density 10-1A/cm². Over a period of one hour, growth of MgO nanorods catalyzed by Au nanoparticles is observed. Eventually the Au nanoparticles fall off, leaving the MgO nanorods for beam induced dissolution. Figure 2 shows the...

  15. The conduction bands of MgO, MgS and HfO2

    OpenAIRE

    de Boer, P. K.; de Groot, R. A.

    1998-01-01

    Electronic structure calculations for MgO, MgS and HfO2 are reported. It is shown that the conduction bands of MgO and MgS have predominantly anion character, contrary to the common picture of the conduction band being derived from cation states. In transition metal oxides, unoccupied anion states are less important due to the presence of metal d states. The anion states are, however, still not negligible for a correct description of the conduction band, as will be shown for HfO2.

  16. Very high residual resistivity ratios of heteroepitaxial superconducting niobium films on MgO substrates

    Science.gov (United States)

    Krishnan, M.; Valderrama, E.; Bures, B.; Wilson-Elliott, K.; Zhao, X.; Phillips, L.; Valente-Feliciano, A.-M.; Spradlin, J.; Reece, C.; Seo, K.

    2011-11-01

    We report residual resistivity ratio (RRR) values (up to RRR-541) measured in thin film Nb grown on MgO crystal substrates, using a vacuum arc discharge, whose 60-160 eV Nb ions drive heteroepitaxial crystal growth. The RRR depends strongly upon substrate annealing and deposition temperatures. X-ray diffraction spectra and pole figures reveal that, as the crystal structure of the Nb film becomes more ordered, RRR increases, consistent with fewer defects or impurities in the lattice and hence longer electron mean free path. A transition from Nb(110) to purely Nb(100) crystal orientation on the MgO(100) lattice occurs at higher temperature.

  17. Very high residual resistivity ratios of heteroepitaxial superconducting niobium films on MgO substrates

    International Nuclear Information System (INIS)

    We report residual resistivity ratio (RRR) values (up to RRR-541) measured in thin film Nb grown on MgO crystal substrates, using a vacuum arc discharge, whose 60-160 eV Nb ions drive heteroepitaxial crystal growth. The RRR depends strongly upon substrate annealing and deposition temperatures. X-ray diffraction spectra and pole figures reveal that, as the crystal structure of the Nb film becomes more ordered, RRR increases, consistent with fewer defects or impurities in the lattice and hence longer electron mean free path. A transition from Nb(110) to purely Nb(100) crystal orientation on the MgO(100) lattice occurs at higher temperature.

  18. Tailoring the microstructure of porous MgO supports for asymmetric oxygen separation membranes: Optimization of thermoplastic feedstock systems

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Clemens, F.; Glasscock, Julie;

    2014-01-01

    Porous magnesium oxide (MgO) structures were prepared by thermoplastic processing for use as supports in asymmetric thin film oxygen transport membranes (OTMs). The open porosity, pore size distribution, and resulting gas permeability of the MgO structures were measured for different feedstock co...

  19. Ethanol-to-Butadiene Conversion over SiO2-MgO Catalysts: Synthesis-Structure-Performance Relationships

    NARCIS (Netherlands)

    Angelici, C.

    2015-01-01

    The work presented in this PhD Thesis provides new insights into the underlying reasons that make SiO2-MgO materials excellent catalysts for the ethanol-to-butadiene Lebedev process. In particular, the preparation technique of choice affects the structural properties of the resulting SiO2-MgO materi

  20. On the conductive properties of MgO films grown on ultrathin hexagonal close-packed Co(0001) layer

    International Nuclear Information System (INIS)

    Here we present a scanning tunneling microscopy study of electrical conductivity of (110)-oriented MgO ultrathin films grown on hexagonal close-packed Co(0001) surface by molecular beam epitaxy, being a good candidate for tunneling barrier for future-generation spintronic devices. Three-dimensional growth of the tunneling barrier, expected for compressive strains emerging at the Co/MgO interface, is demonstrated by reflection high-energy electron diffraction and atomic force microscopy. The 5 eV height of the full barrier of MgO is reached at a layer thickness of 4 nm. Thinner MgO layers exhibit randomly distributed spots of the high conductance on the tunneling current map. The current–voltage curves indicate the existence of vacancies in MgO crystal lattice, lowering the resistivity of the tunneling barrier. - Highlights: • Conductivity of MgO barrier in MgO/hexagonal close-packed-Co bilayer • Conductivity strongly varies with MgO thickness • MgO barrier exhibits randomly distributed spots of particularly high conductance • Tunneling current–voltage curves indicate the existence of vacancies in MgO lattice

  1. Copper implantation defects in MgO observed by positron beam analysis, RBS and X-TEM

    NARCIS (Netherlands)

    Fedorov, A.V.; Veen, A. van; Smulders, P.J.M.; Kooi, B.J.; Hosson, J.Th.M. De

    2000-01-01

    In this work, effects of copper ion implantation in MgO were studied. (100) MgO samples were implanted with 50 keV Cu ions and thermally annealed stepwise in air for 30 minutes at 550, 750, 1000, 1250 and 1350 K. After ion implantation and after each annealing step, the samples were analysed with po

  2. The inlfuence of CAO Cao on the formation of Jianan writing style with strength of character%论曹操对“建安风骨”形成的影响

    Institute of Scientific and Technical Information of China (English)

    廖志斌; 廖锦治

    2014-01-01

    CAO Cao, with his unique political inlfuence and personality charm inspired and convened the world celebrities to establish the “Yexi Literati Group”. He advocated the literary thought of memoir, and objected to the writing of showiness and the natural disposition & intelligence; he sparkplugged to turn the Yueh-Fu’s old topics into new dictions, and created a new ethos of literature; he sparkplugged the writing style of freshness and unconventionality, and reformed the writing abuse of cumbersomeness and pedantry in han dynasty, which made him become "The father of article-transformation". Under his inlfuence, the Jianan literati represented by "three cao", "seven scholars", and CAI Wen-ji formed the writing style of dismalness and generosity, energy and strength with the emotional, frank and upright writing features, ifnally achieved the Jianan writing style with strength of character that had the distinct characteristics of The Times.%曹操以其独特的政治影响和人格魅力感召天下名士,成立邺下文人集团,提倡重实录、反浮华和书写性灵的文学思想,倡导乐府旧题写新辞,开创文学新风气,倡导清峻、通脱文风,改革汉代文赋烦琐迂腐弊疾,成为“改造文章的祖师”。在其影响下,以“三曹”、“七子”和蔡琰为代表的建安文人,以意气骏爽的“文风”和结言端直的“文骨”,形成悲凉慷慨、刚健有力的风格,成就“建安风骨”鲜明的时代特色。

  3. The role of MgO content in ex situ MgB2 wires

    DEFF Research Database (Denmark)

    Kovac, P.; Hugek, I.; Meligek, T.;

    2004-01-01

    An experimental study of the effect of MgO content in the MgB2 powder used for ex situ made composite wires was carried out. Two single-core MgB2/Fe/Cu wires were made using commercial MgB2 powders from Alfa Aesar containing different fraction of MgO. Critical temperature and critical currents of...... as-deformed and heat-treated wires were measured. The differences between the wires are discussed and correlated with the MgO content. It was found that by increasing the amount of MgO, the inter-grain connectivity worsens, but well distributed and low size MgO particles improve flux pinning....

  4. Effects of O defects on adsorption of small Ag clusters on a MgO(001) surface

    International Nuclear Information System (INIS)

    The interaction of Ag atoms with a defective MgO(001) surface is systematically studied based on density functional theory. The Ag clusters are deposited on neutral and charged oxygen vacancies of the MgO(001) surface. The structures of Ag clusters take the shape of simple models of two- or three-dimensional (2D and 3D) metal particles deposited on the MgO surface. When the nucleation of the metal clusters occurs in the Fs (missing neutral O) centre, the interaction with the substrate is considerably stronger than that in the Fs+ (missing O−) centre. The results show that the adsorption of Ag atoms on the MgO surface with oxygen vacancy is stronger than on a clear MgO surface, thereby attracting more Ag atoms to cluster together, and forming atomic islands. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  5. First-principles study of B, C, N and F doped graphene-like MgO monolayer

    Science.gov (United States)

    Wu, Ping; Huang, Min; Cheng, Wenjing; Tang, Fuling

    2016-07-01

    Based on the first-principles calculations, we have investigated the stable geometries, electronic and magnetic properties of the graphene-like MgO monolayer with O atom substituted by B, C, N, and F atoms. The formation energy decreases in the order of B>C>N>F, which may be influenced by the different electronegativities. The band gaps of p-type doped MgO monolayers are tunable due to the emergence of impurity states within the band gap, while F-doped MgO monolayer realizes the transition from semiconductor to metal. The results show that p-type doped MgO monolayer exhibit magnetic behaviors due to polarizations of dopants and surrounding Mg or O atoms near the dopants, while no magnetism is observed in the case of F doped MgO monolayer. These results are potentially useful for spintronic applications and the development of magnetic nanostructures.

  6. Development of the IBAD MgO process for HTS coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Groves, J. R. (James R.); Arendt, P. N. (Paul N.); Foltyn, S. R. (Stephen R.); Jia, Quanxi; Holesinger, T. G. (Terry G.); Kung, H. (Harriett); DePaula, R. F. (Raymond Felix); Dowden, P. C. (Paul C.); Peterson, E. J. (Eric J.); Stan, L. (Liliana); Emmert, L. A. (Luke A.)

    2001-01-01

    We discuss our progress toward depositing IBAD MgO as a template for subsequent deposition of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) high temperature superconductors on metallic substrates. We have refined the process by improving substrate preparation and by using reflected high-energy electron diffraction (RHEED) to monitor the growth of IBAD MgO films. Here we present results on our work to optimize the IBAD MgO process for continuous processing of meter lengths. High quality IBAD MgO has been deposited on moving metal tape for use in coated conductor fabrication. By incorporating optimized processing parameters, we have been able to deposit films on moving metallic substrates with in-plane mosaic spreads near 8{sup o}. The subsequent pulsed laser deposition (PLD) of 1.5 {micro}m thick YBCO films has resulted in superconducting transport critical current densities >1MA/cm{sup 2} (75K,SF) on small area samples.

  7. Resputtering effect during MgO buffer layer deposition by magnetron sputtering for superconducting coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Shaozhu; Shi, Kai; Deng, Shutong; Han, Zhenghe [Applied Superconductivity Research Center, Department of Physics, Tsinghua University, Beijing 100084 (China); Feng, Feng, E-mail: feng.feng@sz.tsinghua.edu.cn; Lu, Hongyuan [Division of Advanced Manufacturing, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Qu, Timing; Zhu, Yuping [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Huang, Rongxia [School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2015-07-15

    In this study, MgO thin films were deposited by radio-frequency magnetron sputtering. The film thickness in the deposition area directly facing the target center obviously decreased compared with that in other areas. This reduction in thickness could be attributed to the resputtering effect resulting from bombardment by energetic particles mainly comprising oxygen atoms and negative oxygen ions. The influences of deposition position and sputtering pressure on the deposition rate were investigated. Resputtering altered the orientation of the MgO film from (111) to (001) when the film was deposited on a single crystal yttria-stabilized zirconia substrate. The density distribution of energetic particles was calculated on the basis of the measured thicknesses of the MgO films deposited at different positions. The divergence angle of the energetic particle flux was estimated to be approximately 15°. The energetic particle flux might be similar to the assisting ion flux in the ion beam assisted deposition process and could affect the orientation of the MgO film growth.

  8. Fabrication of Nd:YAG transparent ceramics with both TEOS and MgO additives

    International Nuclear Information System (INIS)

    Research highlights: → It is well known that the use of TEOS as sintering aid is required to reach fully dense and transparent Nd:YAG ceramics. However, it is difficult to produce high quality transparent Nd:YAG ceramics only using TEOS as sintering aid. In this present work, high quality transparent Nd:YAG ceramic was fabricated using both TEOS and MgO as sintering aids. There have been few reports that both TEOS and MgO were co-added as sintering aids in YAG or Nd:YAG transparent ceramics to date. The transmittance of Nd:YAG ceramic is 83.8% at 1064 nm. The effect of MgO on the optical properties of transparent ceramics was also studied. - Abstract: Neodymium doped YAG transparent ceramics were fabricated by vacuum reactive sintering method using commercial α-Al2O3, Y2O3 and Nd2O3 powders as the starting materials with both tetraethyl orthosilicate (TEOS) and MgO as sintering aids. The morphologies and microstructure of the powders and Nd:YAG transparent ceramics were investigated. Fully dense Nd:YAG ceramics with average grain size of ∼10 μm were obtained by vacuum sintering at 1780 deg. C for 8 h. No pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 83.8% at 1064 nm.

  9. Inter-diffusion study in MgO tunneling magneto-resistive (TMR) system by XPS

    International Nuclear Information System (INIS)

    In this paper, we investigated the elemental inter-diffusion in MgO TMR system, namely, between MgO barrier and free layer (CoFeB, NiFe or their combination) interface and the oxygen diffusion into the capping layers (Ta, Ru, TaN) at elevated temperatures using simple sheet film stack to simplify the results interpretation. Boron, cobalt, iron, and nickel show various diffusion tendencies into the MgO barrier after annealing the sheet film stack. Oxygen has different penetration depth into single CoFeB free layer upon annealing under N2 + Ar protective atmosphere for different capping layers. Ru and TaN capping layer provide much better O2 diffusion barrier, compared with Ta capping layer. This could potentially change the boron segregation tendency at free layer and capping layer interface and thus affect the interface crystallization process and lattice matching between the crystallized CoFeB free layer and the MgO(0 0 1) barrier layer. All these effects will impact the overall TMR performance.

  10. Biaxial Texture Evolution in MgO Films Fabricated Using Ion Beam-Assisted Deposition

    Science.gov (United States)

    Xue, Yan; Zhang, Ya-Hui; Zhao, Rui-Peng; Zhang, Fei; Lu, Yu-Ming; Cai, Chuan-Bing; Xiong, Jie; Tao, Bo-Wan

    2016-04-01

    The growth of multifunctional thin films on flexible substrates is important technologically, because flexible electronics require such a platform. In this study, we examined the evolution of biaxial texture in MgO films prepared using ion beam-assisted deposition (IBAD) on a Hastelloy substrate. Texture and microstructure developments were characterized through in situ reflection high-energy electron diffraction monitoring, x-ray diffraction, and atomic force microscopy, which demonstrated that biaxial texture was developed during the nucleation stage (~2.2 nm). The best biaxial texture was obtained with a thickness of approximately 12 nm. As MgO continued to grow, the influence of surface energy was reduced, and film growth was driven by the attempt to minimize volume free-energy density. Thus the MgO grains were subsequently rotated at the (002) direction toward the ion beam. In addition, an approach was developed for accelerating in-plane texture evolution by pre-depositing an amorphous MgO layer before IBAD.

  11. Structures of metal nanoparticles adsorbed on MgO(001).I.Ag and Au

    Czech Academy of Sciences Publication Activity Database

    Ferrando, R.; Rossi, G.; Levi, A. C.; Kuntová, Zdeňka; Nita, F.; Jelea, A.; Mottet, Ch.; Barcaro, G.; Fortunelli, A.; Goniakowski, J.

    2009-01-01

    Roč. 130, č. 17 (2009), 174702/1-174702/9. ISSN 0021-9606 Institutional research plan: CEZ:AV0Z10100521 Keywords : ab-initio calculations * classical global optimalization * epitaxial layers * nanoparticles * MgO (001) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.093, year: 2009

  12. Preparation of MgO Catalytic Support in Shaped Mesoporous High Surface Area Form

    Czech Academy of Sciences Publication Activity Database

    Gulková, Daniela; Šolcová, Olga; Zdražil, Miroslav

    2004-01-01

    Roč. 76, 1-3 (2004), s. 137-149. ISSN 1387-1811 R&D Projects: GA AV ČR IAA4072306 Institutional research plan: CEZ:AV0Z4072921 Keywords : MgO support * sigh Surface area * texture Subject RIV: CC - Organic Chemistry Impact factor: 2.093, year: 2004

  13. FeO and MgO in plagioclase of lunar anorthosites: Igneous or metamorphic?

    Science.gov (United States)

    Phinney, W. C.

    1994-01-01

    The combined evidence from terrestrial anorthosites and experimental laboratory studies strongly implies that lunar anorthosites have been subjected to high-grade metamorphic events that have erased the igneous signatures of FeO and MgO in their plagioclases. Arguments to the contrary have, to this point, been more hopeful than rigorous.

  14. Preparation and characterization of MgO nanorods sheathed with ZnS

    International Nuclear Information System (INIS)

    MgO nanorods have been grown on Si (100) substrates by using thermal evaporation of Mg3N2 powders with a Vapor-liquid-solid (VLS) mechanism. The as-synthesized MgO nanorods were 100 - 200 nm in diameter and 5 - 7 μm in length. MgO/ZnS core-shell nanorods were also prepared by using sputter deposition of ZnS onto the nanorods. Transmission electron microscopy and X-ray diffraction analyses indicated that the MgO cores and the ZnS shells of the annealed coreshell nanorods were cubic-structured single crystals and amorphous material, respectively. The photoluminescence (PL) measurements of the core-shell nanorods showed a broad emission band centered at approximately 605 nm in the yellow-orange region. The PL emission intensity of the MgO nanorods increased with increasing ZnS shell layer thickness up to a shell layer thickness of 30 nm and then decreased with continued increases in the shell layer thickness. The yellow-orange emission intensity of the MgO/ZnS core-shell nanorods was found to be significantly increased by annealing in an oxidizing atmosphere. The PL emission intensity of the core-shell nanorods was increased further by annealing in a reducing atmosphere. The origin of the PL enhancement by annealing is discussed.

  15. Influence of MgO on structure and optical properties of alumino-lithium-phosphate glasses

    Science.gov (United States)

    Jlassi, I.; Elhouichet, H.; Ferid, M.

    2016-07-01

    MgO doped lithium alumino phosphate glasses (PLA: P2O5+Li2O+Al2O3+MgO) were prepared by melt quenching technique. Raman spectra display three significant peaks at 698, 1164 and 1383 cm-1 attributed to: symmetric stretching vibrations of the bridging oxygen (BO) in the P-O-P chains, symmetric stretching vibrations of the PO2 groups, and the asymmetric vibrations vas(PO2) of the non-bridging oxygen (NBO) atoms, respectively. Also, the density, molar volumes and ion concentration have been discussed and correlated with the structural changes within the glassy matrix. Some optical constants such as refractive index and dispersion parameters (Eo: single-oscillator energy and Ed: dispersive energy) of the glasses were determined. Finally, the values of the optical band gap for direct and indirect allowed transitions have been determined from the absorption edge studies. It is deduced that the values of Eopt increase with increasing MgO content. It was assigned to structural changes induced from the formation of non-bridging oxygen. The Urbach energy (ΔE) was found to decrease from 0.578 to 0.339 eV with increasing MgO content from 0.5 to 2 mol.

  16. Temperature variation of higher-order elastic constants of MgO

    Indian Academy of Sciences (India)

    K M Raju; R K Srivastava; Kailash

    2007-09-01

    An effort has been made for obtaining higher-order elastic constants for MgO starting from basic parameters, viz. nearest-neighbor distance and hardness parameter using Coulomb and Börn–Mayer potentials. These are calculated in a wide temperature range (100–1000 K) and compared with available theoretical and experimental results.

  17. Transient Cataluminescence on Flowerlike MgO for Discrimination and Detection of Volatile Organic Compounds.

    Science.gov (United States)

    Xu, Honglin; Li, Qiuyan; Zhang, Lichun; Zeng, Binrong; Deng, Dongyan; Lv, Yi

    2016-08-16

    Methodologies for simple and rapid identification of gas compounds are needed in the fields of environmental and security. Here, a new and simple method for the discrimination of gas compounds was designed through an interesting transient cataluminescence (TRCTL) phenomenon on the highly efficient MgO materials. The flowerlike MgO with high CTL activity was controllably synthesized via a facile and time-saving aqueous precipitation route and characterized by scanning electron microscopy, powder X-ray diffractometry, high-resolution transmission electron microscopy, and N2 adsorption measurements, etc. With flowerlike MgO working as the sensing material, the newly developed CTL gas sensor exhibited highly active, ultrafast, and characteristic responses toward many analytes; the TRCTL curves thus were obtained and 10 VOCs have been successfully identified. Parallel experimental results show that the controllable synthesis of flowerlike MgO can greatly enhance the discrimination capacities for VOCs. Further, the TRCTL of CHCl3 and C2H5OC2H5 were taken as typical examples to illustrate the possible sensing mechanism, which could contribute to explaining processes of catalytic oxidations. We expect this novel TRCTL concept will be of practical importance for applications including gas detection, gas discrimination, and research of chemical kinetics processes. PMID:27417505

  18. Biaxial Texture Evolution in MgO Films Fabricated Using Ion Beam-Assisted Deposition

    Science.gov (United States)

    Xue, Yan; Zhang, Ya-Hui; Zhao, Rui-Peng; Zhang, Fei; Lu, Yu-Ming; Cai, Chuan-Bing; Xiong, Jie; Tao, Bo-Wan

    2016-07-01

    The growth of multifunctional thin films on flexible substrates is important technologically, because flexible electronics require such a platform. In this study, we examined the evolution of biaxial texture in MgO films prepared using ion beam-assisted deposition (IBAD) on a Hastelloy substrate. Texture and microstructure developments were characterized through in situ reflection high-energy electron diffraction monitoring, x-ray diffraction, and atomic force microscopy, which demonstrated that biaxial texture was developed during the nucleation stage (~2.2 nm). The best biaxial texture was obtained with a thickness of approximately 12 nm. As MgO continued to grow, the influence of surface energy was reduced, and film growth was driven by the attempt to minimize volume free-energy density. Thus the MgO grains were subsequently rotated at the (002) direction toward the ion beam. In addition, an approach was developed for accelerating in-plane texture evolution by pre-depositing an amorphous MgO layer before IBAD.

  19. Removal of azo and anthraquinone reactive dyes from industrial wastewaters using MgO nanoparticles

    International Nuclear Information System (INIS)

    In the present investigation, a porous MgO powder was synthesized and tested for the removal of dyes from aqueous solution. The size of the MgO particles was in the range of 38-44 nm, with an average specific surface area of 153.7 m2/g. Adsorption of reactive blue 19 and reactive red 198 was conducted to model azo and anthraquinone dyes at various MgO dosages, dye concentrations, solution pHs and contact times in a batch reactor. Experimental results indicate that the prepared MgO powder can remove more than 98% of both dyes under optimum operational conditions of a dosage of 0.2 g, pH 8 and a contact time of 5 min for initial dye concentrations of 50-300 mg/L. The isotherm evaluations revealed that the Langmuir model attained better fits to the experimental equilibrium data than the Freundlich model. The maximum predicted adsorption capacities were 166.7 and 123.5 mg of dye per gram of adsorbent for RB 19 and RR 198, respectively. In addition, adsorption kinetic data followed a pseudo-second-order rate for both tested dyes.

  20. Transesterification of palm oil to biodiesel by using waste obtuse horn shell-derived CaO catalyst

    International Nuclear Information System (INIS)

    Highlights: • Cost effective CaO catalyst derived from waste obtuse horn shells. • The optimum biodiesel yield, 86.75% can be achieved under mild reaction conditions. • The catalyst can be reused up to 3 times with biodiesel yield more than 70%. • Deactivation of catalyst was due to leaching of CaO and pores-filling. - Abstract: The calcium oxide catalysts derived from waste obtuse horn shells were utilized in the transesterification of palm oil into biodiesel. This environment-friendly catalyst is thermally activated at 800 °C for 3 h. The resulting CaO catalyst was characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), temperature-programmed desorption of CO2 (TPD-CO2), Brunauer–Emmett–Teller (BET) surface area analysis, and scanning electron microscopy (SEM). XRD patterns of calcined catalyst showed intense peaks of calcium oxide, consistent with XRF results that revealed calcium is the major element present in the obtuse horn shells. High calcination temperature (800 °C) tended to promote agglomeration of fine crystals, resulted in a smaller surface area (0.07 m2/g) as examined by BET. Catalytic activities in the transesterification process had been investigated using one-variable-at-a-time technique. The optimum palm oil conversion was 86.75% under reaction conditions of 6 h, 5 wt.% of catalyst amount and methanol to oil ratio of 12:1. Reusability of this waste shell derived catalyst was examined and results showed that the prepared catalysts are able to be reused up to 3 times with conversion of more than 70% after the third cycles. Although the reusability may not be excellent at the moment, it is still in the exploratory study. More efforts were done to improve its properties and stability

  1. First stage of reaction of molten Al with MgO substrate

    International Nuclear Information System (INIS)

    The Al/MgO couple was produced in vacuum (~ 5 × 10− 4 Pa) by contact heating from RT up to 1000 °C and holding at that temperature for 1 h of a small 4 × 4 × 4 mm aluminium (5 N) sample placed on the [100] MgO single crystal substrate. TEM observations backed with electron diffraction analysis indicated that the interaction between liquid aluminium and MgO starts from a redox reaction producing a continuous layer of MgAl2O4 spinel on the substrate surface. Its growth is controlled by solid state out-diffusion of magnesium and oxygen towards the surface being in contact with liquid metal. The thickening of spinel layer is accompanied by its cracking and infiltration with aluminium. The above process enables local dissolution of the MgO substrate and formation in it of a thin region of interpenetrating metallic channels walled with spinel. The removal of dissolved magnesium through open aluminium channels towards the drop and to vacuum locally produces areas of aluminium enriched with dissolved oxygen, which results in the nucleation of α-Al2O3 at spinel clad walls. The growth of α-Al2O3 is controlled only by the dissolution rate of MgO by aluminium, liquid state diffusion of Mg to drop/vacuum and oxygen to the front of the of α-Al2O3 crystallites growing into MgO substrate. - Highlights: • New unique evidence of first stages of interaction of liquid Al with MgO substrates • Interaction of liquid Al with MgO starts with the formation of a layer MgAl2O4. • Growth of MgAl2O4 is slow as controlled by solid state out-diffusion of Mg and O. • MgAl2O4 serves as a nucleation site for Al2O3 and consumed by it soon after. • Growth of Al2O3 is fast as controlled by diffusion in liquid state

  2. O estatuto político da amizade: A Alma do Osso, de Cao Guimarães

    Directory of Open Access Journals (Sweden)

    Rafael de Almeida

    2013-06-01

    Full Text Available A partir do conceito de amizade proposto por Giorgio Agamben, este ensaio reflete, em uma interface entre estética e política, acerca das relações de poder presentes em A Alma do Osso (Cao Guimarães, 2004. O maior relevo é dado ao modo que o cineasta partilha, por meio do filme, sua existência com o ermitão Dominguinhos da Pedra, bem como as reverberações que isso garante à forma do documentário.

  3. Particle Size Dependence on the Luminescence Spectra of Eu3+:Y2O3 and Eu3+:CaO

    OpenAIRE

    Williams, Diane Keith

    2002-01-01

    Since the Eu3+ ion can occupy different cation sites in a host material, it can serve as a useful probe of nanocrystalline structures to gain more insight into the structural changes that can occur when the particle size is reduced from the bulk to nanometer regime. The use of laser spectroscopy to probe two nanocrystalline structures, Eu3+:Y2O3 and Eu3+:CaO, was investigated. The nanocrystalline structures were prepared by the laser-vaporization-gas-phase condensation of the bulk oxides....

  4. Nanosilica supported CaO: A regenerable and mechanically hard CO2 sorbent at Ca-looping conditions

    OpenAIRE

    Sánchez-Jiménez, P.E.; Pérez-Maqueda, Luis A; J.M. Valverde

    2014-01-01

    This work presents a CO2 sorbent that may be synthesized from low-cost and widely available materials following a simple method basically consisting of impregnation of a nanostructured silica support with a saturated solution of calcium nitrate. In a first impregnation stage, the use of a stoichiometric CaO/SiO2 ratio serves to produce a calcium silicate matrix after calcination. This calcium silicate matrix acts as a thermally stable and mechanically hard support for CaO deposited on it by f...

  5. Dispositivo y procedimiento para la captura de CO2 por carbonatación de CaO

    OpenAIRE

    Abanades García, Juan Carlos; Arias Rozada, Borja; Grasa, Gemma S.

    2011-01-01

    La presente invención se encuadra dentro del campo de obtención de energía a partir combustibles carbonosos con captura de dióxido de carbono para su uso o almacenamiento permanente y en concreto se refiere a dispositivos y procedimientos que hacen posible la captura mejorada de CO2 mediante CaO en procesos de calcinación-carbonatación debido al uso de un recarbonatador donde se pone en contacto a los sólidos parcialmente carbonatados provenientes del carbonatador con CO2 altamente concentrad...

  6. Borges: entre la vindicación del límite y la seducción del caos

    OpenAIRE

    Huici, Adrián

    2009-01-01

    Este artículo analiza el tema de la entropía, es decir, la tendencia al desorden en la vida social e individual en Jorge L. Borges. Estudiamos la dicotomía entre orden y caos, o entre civilización y barbarie en algunos de sus textos como “El Inmortal” o “Historia del guerrero y la cautiva” y enfatizamos el problema del infinito que está en el origen de la entropía This paper studies entropy, namely, the tendency to move toward disorder in individual and social life. We apply the entropy co...

  7. Design of a Novel Fluidized Bed Reactor To Enhance Sorbent Performance in CO2 Capture Systems Using CaO

    OpenAIRE

    Diego de Paz, María Elena; Arias Rozada, Borja; Grasa, Gemma; Abanades García, Juan Carlos

    2014-01-01

    This work deals with the modeling and design of a novel bubbling fluidized bed reactor that aims to improve the CO2 carrying capacity of CaO particles in CO2 capture systems by calcium looping (CaL). Inside the new reactor (the recarbonator) the particles that arrive from the carbonator of the CaL system react with a concentrated stream of CO2, thereby increasing their carbonate content up to a certain value, which can be predicted by means of the model proposed. The recarbonator model presen...

  8. Incorporation of atomic carbon and hydrogen in high-melting oxide - nuclear-chemical, dilatometric and infrared spectroscopical investigations on C- and H-doped MgO and CaO-monocrystals

    International Nuclear Information System (INIS)

    C and H doped monocrystals of MgO and CaO were investigated in a temperature region of 78 K to 1500 K for the chemical state of the doping agents and their temperature-dependent behaviour. Starting with monocrystals obtained by coal arcing, carbon doping was carried out via the nuclear reaction 12C (d,p)13C, whereas hydrogen doping is present from the start of the crystal growth due to remaining moisture of the initial product. Hydrogen is present in the form of OH-contained defects or secondary produced Hz bubbles. All investigations, namely laser microprobe investigations, infrared spectroscopy, CO2 and hydrocarbon formation measurements and argon and O2 atmosphere, C-profile measurements, diffusion measurements, thermal expansion, lead to the result that carbon in the atomic form is present in the lattice on interstitial places or cation vacancies. The reaction mechanisms are discussed. An interaction model (between OH and C defects) does not completely clarify the complex IR spectra in detail, however shows good agreement with the experimental results. (RB)

  9. Synthesis of MgO nanoparticle loaded mesoporous Al2O3 and its defluoridation study

    International Nuclear Information System (INIS)

    Highlights: • Simple and cost effective preparation of MgO nanoparticles loaded mesoporous Al2O3. • Adsorbents possess high surface area and mesoporous structure. • Higher fluoride removal capacity of MgO loaded Al2O3 than that of pure Al2O3. • Faster fluoride adsorption kinetics of MgO loaded Al2O3 from water. - Abstract: MgO nanoparticle loaded mesoporous alumina has been synthesized using a simple aqueous solution based cost effective method for removal of fluoride from water. Wide angle powder X-ray diffraction, nitrogen adsorption desorption analysis, transmission electron microscopy techniques and energy dispersive X-ray spectroscopy were used to characterize the synthesized adsorbents. Synthesized adsorbents possess high surface area with mesoporous structure. The adsorbents have been thoroughly investigated for the adsorption of F− using batch adsorption method. MgO nanoparticle loading on mesoporous Al2O3 enhances the F− adsorption capacity of Al2O3 from 56% to 90% (initial F− concentration = 10 mg L−1). Kinetic study revealed that adsorption kinetics follows the pseudo-second order model, suggesting the chemisorption mechanism. The F− adsorption isotherm data was explained by both Langmuir and Freundlich model. The maximum adsorption capacity of 40MgO@Al2O3 was 37.35 mg g−1. It was also observed that, when the solutions having F− concentration of 5 mg L−1 and 10 mg L−1 was treated with 40MgO@Al2O3, the F− concentration in treated water became <1 mg L−1, which is well below the recommendation of WHO

  10. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

    International Nuclear Information System (INIS)

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles. (paper)

  11. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

    Science.gov (United States)

    Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

    2013-03-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  12. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO.

    Science.gov (United States)

    Vilayurganapathy, S; Devaraj, A; Colby, R; Pandey, A; Varga, T; Shutthanandan, V; Manandhar, S; El-Khoury, P Z; Kayani, Asghar; Hess, W P; Thevuthasan, S

    2013-03-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag(+) ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles. PMID:23403363

  13. Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion

    International Nuclear Information System (INIS)

    Highlights: • The presence of Ca2+/K+ oxide in coal favored the enrichment of toxic Cr(VI) in coal combustion derived fly ash. • Fe2O3 and MgO in coal are critical on the inhibition of Cr(VI) formation during coal combustion. • Cr(VI) formation extent is correlated positively with the standard reduction potential of metal oxide in coal. -- Abstract: The thermodynamics underpinning the interaction of Cr-bearing species with basic metal oxides, i.e. K2O, Fe2O3, MgO and CaO, during the air and oxy-fuel combustion of coal have been examined. The synchrotron-based X-ray adsorption near-edge spectroscopy (XANES) was used for Cr speciation. For the oxides tested, Cr(VI) formation is dominated by the reduction potential of the metals. The oxides of Ca2+ with high reduction potential favored the oxidation of Cr(III), same for K+. The other two basic metals, Fe2O3 and MgO with lower reduction potentials reacted with Cr(III) to form the corresponding chromites at the temperatures above 600 °C. Coal combustion experiments in drop-tube furnace have confirmed the rapid capture of Cr vapors, either trivalent or hexavalent, by CaO into solid ash. The existence of HCl in flue gas favored the vaporization of Cr as CrO2Cl2, which was in turn captured by CaO into chromate. Both Fe2O3 and MgO exhibited less capability on scavenging the Cr(VI) vapor. Particularly, MgO alone exhibited a low capability for capturing the vaporized Cr(III) vapors. However, its co-existence with CaO in the furnace inhibited the Cr(VI) formation. This is beneficial for minimizing the toxicity of Cr in the coal combustion-derived fly ash

  14. Effect of MgO underlayer misorientation on the texture and magnetic property of FePt–C granular film

    International Nuclear Information System (INIS)

    A transmission electron microscope (TEM) based orientation mapping technique and micromagnetic simulations were applied to study the influence of easy axis distribution (EAD) on magnetic properties of FePt–C granular films which were deposited on a single crystalline MgO (0 0 1) substrate and a (0 0 1)-textured poly-crystalline MgO underlayer. The FePt–C film on the polycrystalline MgO underlayer shows smaller perpendicular coercivity, broader switching field distribution and visible in-plane minor loop compared with that deposited on the single crystalline MgO (0 0 1) substrate. Although the grain sizes and their distributions in both films look similar in TEM, orientation mapping and texture analysis revealed that the polycrystalline MgO underlayer introduces significant misorientation in the (0 0 1)-textured FePt grains. Micromagnetic simulations successfully reproduced the large hysteresis in the in-plane magnetization by introducing the specific misorientation distribution of the FePt grains obtained from the texture analysis. The misoriented FePt grains were found to be grown from misoriented MgO grains, indicating that the improvement of the (0 0 1) texture of the MgO underlayer is essential to reduce the in-plane component of FePt based recording media

  15. Utilization of desulfurization gypsum to producing SO{sub 2} and CaO in multi-stage fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Zhu; Wang, Tao; Yang, Hairui; Zhang, Hai; Zhang, Zuyi [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering

    2013-07-01

    With emission control becomes more and more stringent, flue gas desulphurization (FGD) is commonly employed for desulfurization. However, the product of FGD, gypsum, causes the unexpected environmental problems. How to utilize the byproduct of FGD effectively and economically is a challenging task. This paper proposed the new technical process to produce SO{sub 2} and CaO by reducing the gypsum in multi-stage fluidized bed reactor with different atmosphere. In addition, some preliminary experiments were carried out in PTGA. The results show that CO concentration has little effect on the initial decomposing temperature, but affect the decomposing rate of phosphogypsum obviously. The decomposing product composed of CaS and CaO simultaneously. The ratio of the two products was determined by CO concentration. Lower CO content benefits to produce more CO product and more SO{sub 2}. The decomposition reaction of phosphogypsum in reducing atmosphere is parallel competition reaction. Therefore, it is necessary to eliminate the effect of CaS and other byproduct efficiently by the new technology, which utilize multi-atmosphere in multistage fluidized bed reactors.

  16. La teoría d el caos... Esa nube turbulenta que da qué pensar

    Directory of Open Access Journals (Sweden)

    Ruben Antonio Sánchez G.

    1999-10-01

    Full Text Available "Ver las cosas hasta el fondo...¿Y si las cosas no tuvieran fondo?iAh, que bella la superficie!Quizá la superficie sea la esenciaY lo que excede la superficie sea lo que excede a todoY lo que excede a todo no es nada./Oh rostro del mundo, sólo tu, de todos los rostros,Eres la propia alma que reflejas/”PESSOA, Fernando, Poemas inconjuntos 65.(En: Poesías completas de Alberto Caeiro. Valencia: Pre-textos, 1997, p.3 19.Este texto plantea algunos de los problemas suscitados por la teoría del caos.Es decir, pretende mostrar algunas de las cuestiones que han surgido a partir de la formulación de un modo de obtención de conocimiento que parece tener ventajas sobre otros y según algunos de sus difusores, constituye una revolución en la práctica y el saber científicos. En consecuencia, presentaremos a continuación un panorama de estos problemas 01 tanto que, por una parte, nos muestran las posibilidades y los límites de dicha teoría y , por otra, nos indican en qué sentido la teoría del caos puede dar qué pensar.

  17. Evolution of the electronic structure of CaO thin films following Mo interdiffusion at high temperature

    Science.gov (United States)

    Cui, Yi; Pan, Yi; Pascua, Leandro; Qiu, Hengshan; Stiehler, Christian; Kuhlenbeck, Helmut; Nilius, Niklas; Freund, Hans-Joachim

    2015-01-01

    The electronic structure of CaO films of 10-60 monolayer thickness grown on Mo(001) has been investigated with synchrotron-mediated x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Upon annealing or reducing the thickness of the film, a rigid shift of the CaO bands to lower energy is revealed. This evolution is explained with a temperature-induced diffusion of Mo ions from the metal substrate to the oxide and their accumulation in the interface region of the film. The Mo substitutes divalent Ca species in the rocksalt lattice and is able to release electrons to the system. The subsequent changes in the Mo oxidation state have been followed with high-resolution XPS measurements. While near-interface Mo transfers extra electrons back to the substrate, generating an interface dipole that gives rise to the observed band shift, near-surface species are able to exchange electrons with adsorbates bound to the oxide surface. For example, exposure of O2 results in the formation of superoxo species on the oxide surface, as revealed from STM measurements. Mo interdiffusion is therefore responsible for the pronounced donor character of the initially inert oxide, and largely modifies its adsorption and reactivity behavior.

  18. CaO insulator and Be intermetallic coatings on V-base alloys for liquid-lithium fusion blanket applications

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Kassner, T.F. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    The objective of this study is to develop (a) stable CaO insulator coatings at the Liquid-Li/structural-material interface, with emphasis on electrically insulating coating that prevent adverse MHD-generated currents from passing through the V-alloy wall, and (b) stable Be-V intermetallic coating for first-wall components that face the plasma. Electrically insulating and corrosion-resistant coatings are required at the liquid-Li/structural interface in fusion first-wall/blanket application. The electrical resistance of CaO coatings produced on oxygen-enriched surface layers of V-5%Cr-5%Ti by exposing the alloy to liquid Li that contained 0.5-85 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600{degrees}C. Crack-free Be{sub 2}V intermetallic coatings were also produced by exposing V-alloys to liquid Li that contained Be as a solute. These techniques can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coatings are formed by liquid-phase reactions.

  19. Annealing effect of thermal spike in MgO thin film prepared by cathodic vacuum arc deposition

    International Nuclear Information System (INIS)

    MgO films were prepared by using pulsed cathodic vacuum arc deposition technique. The substrate bias voltage was in the range of −150 to −750 V. Film structure was investigated by X-ray diffraction (XRD). The annealing effect of thermal spike produced by the impacting of energetic ions was analyzed. The calculated results showed that the lifetime of a thermal spike generated by an energetic ion with the energy of 150 eV was less than one picosecond and it was sufficient to allow Mg2+ or O2- to move one bond length to satisfy the intrinsic stress relief in the affected volume. The MgO(200) lattice spacings of the films deposited at different bias voltages were all larger than the ideal value of 2.1056 Å. As the bias amplitude increased the lattice spacing decreased, which indicated that the compressive stress in the film was partially relieved with increasing impacting ion energy. The stress relief also could be reflected from the film orientation with bias voltage. The biaxial elastic modulus for MgO(100), MgO(110) and MgO(111) planes were calculated and they were M(100) = 199 GPa, M(110) = 335 GPa and M(111) = 340 GPa, respectively. The M values indicated that the preferred orientation will be MgO(200) due to the minimum energy configuration when the lattice strain was large. It was confirmed by the XRD results in our experiments. - Highlights: • MgO thin films with preferred orientation were obtained by CVAD technique. • Annealing effect of a thermal spike in MgO film was discussed. • Lattice spacing of MgO film decreased with the increase of bias voltage. • Film preferred orientation changed from (200) to (220) as the bias voltage increased

  20. The Thinking of the Disputes of Cao- Cao Tomb - On our country archaeology proof system's flaw and consmnmation%曹操墓纠纷的理性思考——论我国考古认证制度的缺失与完善

    Institute of Scientific and Technical Information of China (English)

    赵玲

    2011-01-01

    曹操墓惊现河南安阳后,质疑纷起。“挺曹派”言之凿凿;“反曹派”学者认为证据不足,定性为时过早;公众质疑矛头直指政府和学术权威的公信力。双方法理辩论的背后折射出我国考古论证制度的不完善。%After Tomb of Cao-Cao startled presently, Anyang, Henan, the question flared up, "The Cao faction" said with certainty; "the counter-Cao faction" scholars believe that the evidence is insufficient and the qualitative is too early. The public question is d

  1. Fabrication and formation mechanism of hollow MgO particles by pulsed excimer laser ablation of Mg in liquid

    International Nuclear Information System (INIS)

    We report on the formation of hollow MgO particles by excimer laser ablation of bulk Mg in water and aqueous solutions of sodium dodecyl sulfate (SDS) and sodium citrate (SC). Lamellar nanostructures of Mg(OH)2 also formed in water, but the formation could be avoided by the addition of SDS or SC. Laser ablation produced not only Mg species that were oxidized into MgO and Mg(OH)2 in water, but also cavitation bubbles. The bubble interfaces trapped the MgO nanoparticles to decrease the surface free energy of the system, finally resulting in hollow particles.

  2. Depth-selective 2D-ACAR and coincidence Doppler investigation of embedded Au nanocrystals in MgO

    International Nuclear Information System (INIS)

    We present a depth-selective 2D-ACAR and two-detector Doppler broadening study on Au nanocrystals in monocrystalline MgO(100), produced in sub-surface layers by ion implantation and subsequent thermal annealing to temperatures beyond the stability range of vacancy clusters in MgO. In contrast to the case of Li nanocrystals, it was found that positrons do not trap inside the Au nanocrystals, but only in defects at the nanocrystal-to-host interface (attached vacancy clusters). This is interpreted in terms of the positron affinity of Au, MgO and the defects. (orig.)

  3. First principles study of the adsorption of MgO molecules on a clean Fe(001) surface

    OpenAIRE

    Wiśnios, D.; Kiejna, A.; Korecki, J.

    2015-01-01

    The adsorption of MgO molecules on a Fe(001) surface was studied using density functional theory (DFT) and projector augmented wave methods. The energetically most favored configurations for different adsorption sites considered were identified. The most preferable adsorption geometry is when the MgO molecules are parallel to the surface, with Mg in the interstitial site and O in on-top of the Fe atom. During the adsorption of subsequent MgO molecules in this geometry, a sharp, non-oxidized i...

  4. Comparison of Sol Gel and Dehydration Magnesium Oxide (MgO) as a Catalyst in Michael Addition Reaction

    OpenAIRE

    Hanis Mohd Yusoff; Nuur Ul Hazwani; Norhafiefa Hassan; Fatin Izwani

    2015-01-01

    Magnesium oxide (MgO) was prepared by dehydration of magnesium carbonate method and sol gel method. The prepared MgO powders were calcined at the temperature of 200, 400, 600, and 800 ºC for two hours. Then, the samples were characterized by using fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). In order to investigate the prepared MgO, the samples were applied in Michael addition reaction to produce diethyl 2-(3-oxo-1,3-dipehnyl...

  5. Structural, chemical and electronic properties of the Co2MnSi(001)/MgO interface

    OpenAIRE

    Fetzer, Roman; Wüstenberg, Jan-Peter; Taira, Tomoyuki; Uemura, Tetsuya; Yamamoto, Masafumi; Aeschlimann, Martin; Cinchetti, Mirko

    2012-01-01

    The performance of advanced magnetic tunnel junctions build of ferromagnetic (FM) electrodes and MgO as insulating barrier depends decisively on the properties of the FM/insulator interface. Here, we investigate interface formation between the half-metallic compound Co2MnSi (CMS) and MgO by means of Auger electron spectroscopy, low energy electron diffraction and low energy photoemission. The studies are performed for different annealing temperatures TA and MgO layer coverages (4, 6, 10, 20 a...

  6. Basicity for blast furnace-type slag containing B2O3 and high MgO

    Institute of Scientific and Technical Information of China (English)

    黄振奇; 蔡亚旻; 朱文非; 杨祖磐

    2003-01-01

    There is quite abundant resource of ludwigite ore in Liaoning Province of China. Content of MgO in the slag of pyrometallurgical separation of boron from iron is much higher than that in the ordinary slags. Through the equilibrium partition ratio of sulfur LS between the metal and the slag in an atmosphere of CO-N2, the acidic coefficients for B2O3 and the basic coefficients for MgO were estimated. The basic formulae were given for the blast furnace-type slag containing B2O3 and high MgO.

  7. Adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO surface

    KAUST Repository

    Yadav, Manoj Kumar

    2016-06-16

    The adsorption and dissociation of dinitrogen on transition metal (Ta, W and Re) doped MgO(100) surface has been studied employing density functional theory. It is found that all these transition metals (TM) on MgO(100) surface are capable of adsorbing dinitrogen (N2), however there is no dissociative adsorption of N2 on single transition metal dopant. When two TM atoms are doped on MgO(100) surface, dissociative adsorption of dinitrogen occurs in all the three cases. Whether the dissociation is spontaneous or is it associated with activation barrier depends on the orientation of N2 molecule approaching the dopant site.

  8. Calcium adsorption on MgO(100): energetics, structure, and role of defects.

    Science.gov (United States)

    Zhu, Junfa; Farmer, Jason A; Ruzycki, Nancy; Xu, Lijun; Campbell, Charles T; Henkelman, Graeme

    2008-02-20

    The adsorption of Ca on the MgO(100) surface at 300 K has been studied using microcalorimetry, in combination with LEED, AES, ISS, work function, sticking probability measurements, and density functional theory (DFT) calculations. The MgO(100) thin films (approximately 4 nm thick) were grown epitaxially on a 1 microm thick Mo(100) single-crystal. The sticking probability of Ca on MgO(100) at 300 K is unity. On the basis of AES and ISS measurements, it was determined that Ca grows mainly as 3D particles on the MgO(100) surface with a density of approximately 1 x 10(12) islands/cm2. Ca adsorbs initially at defect sites with a very high heat of adsorption (approximately 410 kJ/mol). DFT calculations attribute this high initial heat to Ca binding to kink sites (376 kJ/mol), step sites (205 kJ/mol), and lower concentrations of stronger binding sites. The heat of adsorption decreases rapidly with coverage, reaching a minimum of 162 kJ/mol at approximately 0.3 ML, where Ca is mainly adding to small 3D Ca clusters. Afterward, it increases to the value of bulk Ca heat of sublimation (178 kJ/mol) at approximately 1.2 ML, attributed to the increase in stability with increasing Ca particle size. A 1.0 eV decrease of the work function with Ca coverage from 0 to 0.3 ML indicates that Ca adsorbed at defects is cationic, in agreement with calculations showing that Ca donates electron density to the MgO. Light ion sputtering of the MgO(100) surface generates point defects, but these do not change the heat of adsorption versus coverage, implying that they do not nucleate Ca particles. Oxygen vacancies are a likely candidate; DFT calculations show that F and F+ center vacancies bind Ca more weakly than terrace sites. More extensive sputtering creates extended defects (such as steps and kinks) that adsorb Ca with heats of adsorption up to approximately 400 kJ/mol, similar to that at the intrinsic defect sites. PMID:18229925

  9. First-principles calculations of perpendicular magnetic anisotropy in Fe1−x Co x /MgO(001) thin films

    OpenAIRE

    Cai, Guanzhi; Wu, Zhiming; Guo, Fei; Wu, Yaping; Heng LI; Liu, Qianwen; FU, MINGMING; CHEN Ting; Kang, Junyong

    2015-01-01

    The perpendicular magnetic anisotropy (PMA) of Fe1−x Co x thin films on MgO(001) was investigated via first-principles density-functional calculations. Four different configurations were considered based on their ground states: Fe/MgO, Fe12Co4/MgO, Fe10Co6/MgO, and Fe8Co8/MgO. As the Co composition increases, the amplitude of PMA increases first from Fe/MgO to Fe12Co4/MgO, and then decreases in Fe10Co6/MgO; finally, the magnetic anisotropy becomes horizontal in Fe8Co8/MgO. Analysis based on t...

  10. Morphology, surface topography and optical studies on electron beam evaporated MgO thin films

    Indian Academy of Sciences (India)

    A Chowdhury; J Kumar

    2006-10-01

    Electron beam evaporated thin films of MgO powder synthesized by burning of magnesium ribbon in air and sol–gel technique are studied for their microstructure (SEM), surface topography (AFM), and optical transmission behaviour (UV-visible spectroscopy). MgO thin films are shown to be either continuous or have mesh like morphology. The bar regions are believed to be of magnesium hydroxide formed due to absorption of moisture. Their AFM images exhibit columnar/pyramidal/truncated cone structure, providing support to the 3D Stranski–Krastanov model for film growth. Further, they are shown to have high transmittance (∼90%) in the wavelength range 400–600 nm, but absorb radiation below 350 nm substantially giving signature of a band transition.

  11. Growth of YBCO film on SrRuO3-buffered MgO substrate

    International Nuclear Information System (INIS)

    The superconducting, crystalline, and morphological properties of YBCO films deposited on SrRuO3-buffered MgO substrates were studied at various deposition temperatures. The film deposited at T = 770 deg. C had the best superconducting properties (critical current density of 2.5 x 106 A cm-2 and critical transition temperature of 91 K). Scanning electron micrographs of this film revealed uniform and well-connected grains. X-ray analyses revealed that the Y BCO/SrRuO3/MgO film fabricated at 770 deg. C had good in-plane and out-of-plane textures. Raman spectroscopy showed that this film had the best out-of-plane texture and orthorhombic I domains

  12. Products of hydratation in fine grained mixtures MgO – SiO2

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the influence of time of ageing on phase evolution of paste from MgO-SiO2-H2O phase system. The paste was composed of fine grained sintered magnesia and microsilica in 1:2 molar ratio and water, with water to solid ratio equal 0,5. After preparation the paste was ageing during specified time up to 180 days in temperature 20° C. Phase composition of mixture of MgO and SiO2 with water was studied by XRD, DTA-TGA. The analysis revealed that product of reaction in mixture of MgO, SiO2 and water was a probably poorly crystalline magnesium silicate

  13. Process for growing a film epitaxially upon a MgO surface

    Science.gov (United States)

    McKee, Rodney Allen; Walker, Frederick Joseph

    1997-01-01

    A process and structure wherein optical quality perovskites, such as BaTiO.sub.3 or SrTiO.sub.3, are grown upon a single crystal MgO substrate involves the epitaxial build up of alternating planes of TiO.sub.2 and metal oxide wherein the first plane grown upon the MgO substrate is a plane of TiO.sub.2. The layering sequence involved in the film build up reduces problems which would otherwise result from the interfacial electrostatics at the first atomic layers, and these oxides can be stabilized as commensurate thin films at a unit cell thickness or grown with high crystal quality to thicknesses of 0.5-0.7 .mu.m for optical device applications.

  14. Comment on " Studies on nanoporous glassy carbon as a new electrochemical capacitor material [Y. Wen, G. Cao, Y. Yang, J. Power Sources 148 (2005) 121-128

    Science.gov (United States)

    Braun, Artur

    Gas-phase activated monolithic glassy carbon was used as electrochemical double layer capacitor electrode by a research team of Siemens AG in the early 1980s [1], J. Miklos, K. Mund, W. Naschwitz, Siemens AG, Offenlegungsschrift DE 30 11 701 A1, German Patent (1980). Wen et al. [2] (Y.H. Wen, G.P. Cao, J. Cheng, Y.S. Yang, New Carbon Mater. 18(3) (2003) 219, and [3] Y.H. Wen, G.P. Cao, Y.S. Yang, J. Power Sources 148 (2005) 121, have repeatedly questioned the performance of this glassy carbon based supercapacitor electrode concept. This asks for some comments.

  15. High-index Cu2O (113) film on faceted MgO (110) by molecular beam epitaxy

    Science.gov (United States)

    Huo, Wenxing; Shi, Jin'an; Mei, Zengxia; Liu, Lishu; Li, Junqiang; Gu, Lin; Du, Xiaolong; Xue, Qikun

    2015-06-01

    We report the growth of single-oriented Cu2O (113) film on faceted MgO (110) substrate by radio-frequency plasma assisted molecular beam epitaxy. A MgO {100} faceted homoepitaxial layer was introduced beforehand as a template for epitaxy of Cu2O film. The epitaxial relationship is determined to be Cu2O (113)//MgO (110) with a tilt angle of 4.76° and Cu2O [ 1 1 bar 0]//MgO [ 1 1 bar 0] by the combined study of in-situ reflection high-energy electron diffraction and ex-situ X-ray diffraction and transmission electron microscopy. The film demonstrates a good p-type conductivity and excellent optical properties, indicating that this unique approach is potentially applicable for high-index film preparation and device applications.

  16. Study on Aldol Condensation of HCHO and CH3CHO over MgO Catalysts Modified by Lanthanum and Cerium

    Institute of Scientific and Technical Information of China (English)

    王幸宜; 李春香; 杨菊群

    2004-01-01

    Aldol condensation of HCHO and CH3CHO over MgO, modified MgO and Al2O3 with rare earth oxides, was studied. The measurement of adsorption of pyrrole on catalysts by in-situ FT-IR and NH3 TPD indicated that the addition of elements La or Ce into MgO increased the acidity of the solid. In-situ FT-IR showed that the activation of-C=O in HCHO adsorbed on CeO-MgO and La2O3-MgO occurred. The measurement of catalytic activity implied that the modified catalysts can promote the formation of pentaerythritol, dipentaerthritol and tripentaerythritol.

  17. Electronic properties of Fe, Co, and Mn ultrathin films at the interface with MgO(001)

    International Nuclear Information System (INIS)

    We have studied the electronic and magnetic properties of Co, Fe, and Mn(001) epitaxial monolayers in contact with a single-crystalline MgO(001) tunnelling barrier using x-ray photoemission spectroscopy (XPS), x-ray absorption spectroscopy (XAS), and x-ray magnetic circular dichroism (XMCD) measurements. The XPS and XAS analysis clearly demonstrate the weak hybridization between the MgO barrier and Fe or Co. On the contrary, a net oxidization of the Mn layer in contact with the MgO layer was observed. The magnetic properties were characterized by probing the XMCD signal of a unique atomic plane of transition metal in contact with MgO. The Co and Fe ferromagnetic behavior were observed to be enhanced at the metal and oxide interface. Finally, no average magnetization was detected at the Mn/MgO interface, which was assumed to come from the Mn oxidization

  18. Magnetic resonance of Cr3+ and Mn2+ in MgO

    International Nuclear Information System (INIS)

    The magnetic resonance linewidth of Cr3+ and Mn2+ in magnesia (MgO) was measured in polycrystalline samples doped with different concentrations of chromium and manganese (0.03 - 1.00 cations%). The linewidth was found to change significantly with chromium and manganese concentration. The experimental results show that magnetic resonance can be used to measure, in a non-destructive manner, small concentrations of chromium and manganese in commercial magnesia. (Author)

  19. Spin-polarized transport across a MgO(001) barrier: Magnetoresistance and magnetic coupling

    OpenAIRE

    Duluard, Amandine

    2012-01-01

    Epitaxial magnetic tunnel junctions Fe/MgO/Fe(001) exhibit noteworthy behaviors for both small and large MgO thicknesses. In the first case, a strong antiferromagnetic interaction between Fe layers is observed, whereas symmetry filtering effects occur for large barriers, leading to high TMR values. The aim of the experiments performed during this thesis is to study and link these two behaviors. We consider the effect of a modulation of electrodes and/or interfaces crystalline structure on spi...

  20. Polaronic distortion and vacancy-induced magnetism in MgO

    OpenAIRE

    Sanvito, Stefano

    2010-01-01

    The electronic structure of the neutral and singly charged Mg vacancy in MgO is investigated using density functional theory. For both defects, semilocal exchange correlation functionals such as the local spin density approximation incorrectly predict a delocalized degenerate ground state. In contrast, functionals that take strong correlation effects into account predict a localized solution, in agreement with spin resonance experi- ments. Our results, obtained with the HSE hybrid...

  1. O(minus 2) grain boundary diffusion and grain growth in pure dense MgO

    Science.gov (United States)

    Kapadia, C. M.; Leipold, M. H.

    1973-01-01

    Grain growth behavior in fully dense compacts of MgO of very high purity was studied, and the results compared with other similar behaving materials. The activation energy for the intrinsic self-diffusion of Mg(2minus) is discussed along with the grain boundary diffusion of O(2minus). Grain boundary diffusion of O(2minus) is proposed as the controlling mechanism for grain growth.

  2. Properties og High Surface Area MgO Prepared for Catalytic Applications

    Czech Academy of Sciences Publication Activity Database

    Gulková, Daniela; Šolcová, Olga; Zdražil, Miroslav

    Bratislava : Slovak University of Technology, 2004 - (Markoš, J.; Štefuca, V.), s. 207 ISBN 80-227-2052-6. [International Conference of Slovak Society of Chemical Engineering /31./. Tatranské Matliare (SK), 24.05.2004-28.05.2004] R&D Projects: GA AV ČR IAA4072306 Institutional research plan: CEZ:AV0Z4072921 Keywords : application * mgo * properties Subject RIV: CF - Physical ; Theoretical Chemistry

  3. Catalytic growth of N-doped MgO on Mo(001)

    OpenAIRE

    Grob, Martin; Pratzer, Marco; Morgenstern, Markus; Ležaić, Marjana

    2012-01-01

    A simple pathway to grow thin films of N-doped MgO (MgO:N), which has been found experimentally to be a ferromagnetic d0 insulator, is presented. It relies on the catalytic properties of a Mo(001) substrate using growth of Mg in a mixed atmosphere of O2 and N2. Scanning tunneling spectroscopy reveals that the films are insulating and exhibit an N-induced state slightly below the conduction band minimum.

  4. The phase diagram and transport properties of MgO from theory and experiment

    Science.gov (United States)

    Shulenburger, Luke

    2013-06-01

    Planetary structure and the formation of terrestrial planets have received tremendous interest due to the discovery of so called super-earth exoplanets. MgO is a major constituent of Earth's mantle, the rocky cores of gas giants and is a likely component of the interiors of many of these exoplanets. The high pressure - high temperature behavior of MgO directly affects equation of state models for planetary structure and formation. In this work, we examine MgO under extreme conditions using experimental and theoretical methods to determine its phase diagram and transport properties. Using plate impact experiments on Sandia's Z facility the solid-solid phase transition from B1 to B2 is clearly determined. The melting transition, on the other hand, is subtle, involving little to no signal in us-up space. Theoretical work utilizing density functional theory (DFT) provides a complementary picture of the phase diagram. The solid-solid phase transition is identified through a series of quasi-harmonic phonon calculations and thermodynamic integration, while the melt boundary is found using phase coexistence calculations. One issue of particular import is the calculation of reflectivity along the Hugoniot and the influence of the ionic structure on the transport properties. Particular care is necessary because of the underestimation of the band gap and attendant overestimation of transport properties due to the use of semi-local density functional theory. We will explore the impact of this theoretical challenge and its potential solutions in this talk. The integrated use of DFT simulations and high-accuracy shock experiments together provide a comprehensive understanding of MgO under extreme conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  5. Thermodynamic modeling of the Sc2O3-MgO phase diagram

    International Nuclear Information System (INIS)

    The Sc2O3-MgO system consists of one liquid and two solid solutions. A relatively simple approach is used to model the solution phases, which are treated as the regular and the sub-regular solutions of the end-members. The solution parameters are derived from the phase equilibrium data. The thermodynamic calculations using the model allow the determination of the liquidus, solidus, solvus, and metastable liquid miscibility gap. Also the lattice stabilities of the components are evaluated.

  6. Transmission electron microscopy characterization of CrN films on MgO(001)

    International Nuclear Information System (INIS)

    Two CrN(001) films with different thickness were grown on MgO(001) substrates using unbalanced d.c. magnetron sputtering. The morphology and interfacial structure of the films are characterized by using conventional transmission electron microscopy, weak-beam dark-field microscopy and spherical aberration (CS)-corrected high-resolution transmission electron microscopy. The microscopy studies revealed the well-known cube-on-cube orientation relationship. While an interface dislocation network with b→=½aCrN<100> edge dislocations was identified, only part of the lattice mismatch is relaxed. The misfit dislocation structure and growth defects are analyzed and discussed based on the weak-beam dark-field and high-resolution transmission electron microscopy results. - Highlights: • Two CrN films were sputtered on MgO(001) substrates under various deposition conditions. • The CrN films nucleate epitaxially with a cube-on-cube orientation relationship. • Transmission electron microscopy shows the existence of interface dislocation networks. • The misfit between the CrN films and MgO substrates is only partially relaxed. • CrN deposition at higher bias voltage leads to an increased defect density

  7. Surface dynamics of Cu and Ag atoms on hydroxylated MgO(001) surfaces

    International Nuclear Information System (INIS)

    Density-functional theory calculations were performed to investigate the surface dynamics of Cu and Ag (XM) atoms on MgO(001) surfaces with surface-functional hydroxyl groups. The adsorption, diffusion, bonding, and electronic structure of XM on these surfaces are presented. The results indicate a large energy gain in the adsorption of XM on MgOhdr(001) with respect to XM on MgO(001). This suggests that the adsorption of XM is stronger on MgOhdr(001). Further analysis shows that in the presence of surface hydroxyl groups, XM atoms preferentially form XMOH complexes instead of XM dimers. The surface diffusion barriers of XMOH on MgO(001) [XM on MgOhdr(001)] are calculated. CuOH is found to have a higher surface diffusion energy barrier than AgOH, but a slightly lower energy barrier to diffusion than AuOH. Therefore, sintering of Ag on MgOhdr(001) surfaces is expected to be different from that of Cu or Au. Finally, the electronic structures and charge rearrangements of XM on MgOhdr(001) are presented and compared with those of Au on MgOhdr(001).

  8. Unusual dissociative adsorption of H2 over stoichiometric MgO thin film supported on molybdenum

    Science.gov (United States)

    Song, Zhenjun; Xu, Hu

    2016-03-01

    The dissociation of a hydrogen molecule on perfect MgO(0 0 1) films deposited on Mo(0 0 1) surface is investigated systematically using periodic density-functional theory (DFT) method. The unusual adsorption behavior of heterolytic dissociative hydrogen molecule at neighboring surface oxygen and surface magnesium, is clarified here. To our knowledge, this heterolytic dissociative state has never been found before on bulk MgO(0 0 1) or metal supported perfect MgO(0 0 1) surfaces (without low coordination sites). The results confirm that, in all cases, the heterolytic dissociation is much more favorable that homolytic dissociation both energetically and kinetically. The energy differences between two dissociative states are very large, in the range of 1.1 eV-1.5 eV for Mo supported 1 ML-3 ML oxide films, which inhibits, to a great extent, the homolytic dissociation in the respect of reaction thermodynamics. The energy barriers of heterolytic dissociation are about 0.5 eV, much lower that the barrier of homolytic dissociation. The transformation reaction on thick films will be more endothermic. Passing through heterolytic dissociation state has significantly lowered the reaction heat and the energy barrier for obtaining homolytic dissociative structure, which makes the homolytic splitting of H2 easier on 2 ML oxide films. The results provide a useful strategy for enhancing the reactivity of the nonreducible metal oxide.

  9. Electronic structure and spectroscopy of the MgO2+ cation

    International Nuclear Information System (INIS)

    Highly correlated ab initio methods are used to investigate the lowest MgO2+ electronic states. Our computations confirm the existence of the strongly bent (MgO2+X∼2A2) form and the weakly bound l-MgOO+(X∼4Σ-) charge quadrupole complex. For both isomers, the three-dimensional potential energy surfaces (3D-PESs) of their electronic ground states are mapped in internal coordinates not far from their respective equilibrium geometries. Then a set of spectroscopic parameters is derived using second order perturbation theory. The rovibrational spectra are also deduced variationally. One-dimensional cuts of the 3D-PESs of the lowest doublet and quartet electronic states of MgO2+ along the RMgO and ROO stretchings and bending are calculated, covering both the molecular and the asymptotic regions. These curves are used later for discussing the metastability of this cation and to propose a plausible mechanism for the Mg+ + O2 atmospheric ion-molecule reaction

  10. Unusual dissociative adsorption of H2 over stoichiometric MgO thin film supported on molybdenum

    CERN Document Server

    Song, Zhenjun

    2015-01-01

    The dissociation of a hydrogen molecule on MgO(001) films deposited on Mo(001) surface is investigated systematically using periodic density-functional theory method. The unusual adsorption behavior of heterolytic dissociative hydrogen molecule at neighboring surface oxygen and surface magnesium, is clarified here. To my knowledge, this heterolytic dissociative state has never been found before on bulk MgO(001) or metal supported MgO(001) surfaces. The results confirm that, in all cases, the heterolytic dissociation is much more favorable that homolytic dissociation both energetically and kinetically. The energy difference between two dissociative states are very large, in the range of 1.1 eV ~ 1.5 eV for Mo supported 1 ML ~ 3 ML oxide films, which inhibits, to a great extent, the homolytic dissociation in the respect of reaction thermodynamics. The energy barrier of heterolytic dissociation are about 0.5 eV, much lower that the barrier of homolytic dissociation. The transformation reaction on thick films wil...

  11. Epitaxial growth of bcc transition metal films and superlattices onto MgO (111), (011) and (001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mattson, J.E.; Fullerton, E.E.; Sowers, C.H.; Bader, S.D.

    1994-04-01

    We demonstrate epitaxial growth of the bcc transition metals Nb, Mo, Fe, and Cr via sputtering onto single crystal MgO substrates. The epitaxial growth orientations are (011), (112) and (001) when grown onto MgO (111), (011) and (001), respectively. Further we demonstrate that under appropriate growth conditions, superlattices of these materials (e.g., Fe/Cr, Fe/V and Mo/V) can be grown with the same epitaxial order as the films.

  12. Synthesis of Nanocrystalline MgO Particles by Combustion Followed by Annealing Method Using Hexamine as a Fuel

    OpenAIRE

    Balamurugan, S.; Ashna, L.; Parthiban, P.

    2014-01-01

    In this work, nanocrystalline MgO particles were prepared through combustion method using magnesium nitrate as oxidizer and hexamine as a fuel. The materials obtained by combustion method were subsequently annealed at 800°C for 3 h to improve the crystallinity and phase purity. The obtained MgO nanomaterials were characterized by powder X-ray diffraction analysis (XRD), infrared (IR) spectroscopy, photoluminescence (PL), near-infrared (NIR) spectroscopy, and scanning electron microscopy (SEM)...

  13. Fabrication and performance of a tubular ceria based oxygen transport membrane on a low cost MgO support

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Søgaard, Martin; Clemens, F.;

    2015-01-01

    A 30 μm thin-film tubular CGO (Ce0.9Gd0.1O1.95−δ) membrane with catalytic layers on both sides has been prepared by dip-coating on a low cost, porous magnesium oxide (MgO) support. The MgO support was fabricated through a thermoplastic extrusion process. Support, thin membrane and catalytic layers...

  14. PDMS-SiO2-TiO2-CaO hybrid materials - Cytocompatibility and nanoscale surface features.

    Science.gov (United States)

    Almeida, J Carlos; Wacha, András; Gomes, Pedro S; Fernandes, M Helena R; Fernandes, M Helena Vaz; Salvado, Isabel M Miranda

    2016-07-01

    Two PDMS-SiO2-TiO2-CaO porous hybrid materials were prepared using the same base composition, precursors, and solvents, but following two different sol-gel procedures, based on the authors' previous works where for the first time, in this hybrid system, calcium acetate was used as calcium source. The two different procedures resulted in monolithic materials with different structures, microstructures, and surface wettability. Even though both are highly hydrophobic (contact angles of 127.2° and 150.6°), and present different filling regimes due to different surface topographies, they have demonstrated to be cytocompatible when tested with human osteoblastic cells, against the accepted idea that high-hydrophobic surfaces are not suitable to cell adhesion and proliferation. At the nanoscale, the existence of hydrophilic silica domains containing calcium, where water molecules are physisorbed, is assumed to support this capability, as discussed. PMID:27127030

  15. Optical detection of magnetic resonance of the F-centre in CaO in its phosphorescent state

    International Nuclear Information System (INIS)

    The F-centre in CaO consists of two electrons trapped in an oxygen vacancy. The centre possesses bound excited states, of which the phosphorescent 3Tsub(1u) state is a Jahn-Teller state. Jahn-Teller systems have been of interest in many investigations. However, detailed experimental studies about the relaxation paths for the Jahn-Teller states are relatively few. The author studies by means of optical detection of magnetic resonance (ODMR) and phosphorescence microwave double resonance (PMDR) techniques the relaxation between the components of the 3Tsub(1u) state, the magnetic properties of the individual spin-vibronic Jahn-Teller states and the inhomogeneous line broadening in the ODMR and PMDR spectra. (Auth.)

  16. Hydrogen-rich gas production via CaO sorption-enhanced steam gasification of rice husk: a modelling study.

    Science.gov (United States)

    Beheshti, Sayyed Mohsen; Ghassemi, Hojat; Shahsavan-Markadeh, Rasoul; Fremaux, Sylvain

    2015-01-01

    Gasification is a thermochemical process in which solid or liquid fuels are transformed into synthesis gas through partial oxidation. In this paper, a kinetic model of rice husk gasification has been developed, which is interesting for the applications of the syngas produced. It is a zero-dimensional, steady-state model based on global reaction kinetic, empirical correlation of pyrolysis and is capable of predicting hydrogen yield in the presence of sorbent CaO. The model can also be used as a useful tool to investigate the influence of process parameters including steam/biomass ratio, CaO/fuel ratio (CaO/Fuel), and gasification temperature on hydrogen efficiency, CO2 capture ratio (CCR), and average carbonation conversion (Save). Similar to hydrogen formation, CCR also increases with increasing CaO/Fuel, but an opposite trend is exhibited in Save. Model predictions were compared with available data from the literature, which showed fairly good agreement. PMID:25403373

  17. Integration of biaxally aligned conducting oxides with silicon using ion-beam assisted deposited MgO templates

    Energy Technology Data Exchange (ETDEWEB)

    Park, B. H. (Bae Ho); Groves, J. R. (James R.); DePaula, R. F. (Raymond Felix); Jia, Quanxi; Arendt, P. N. (Paul N.); Emmert, L. A. (Luke A.)

    2001-01-01

    Two conducting oxides, La{sub 0.5}Sr{sub 0.5}CoO{sub 3}(LSCO) and SrRuO{sub 3}, were deposited by pulsed laser ablation onto silicon substrates coated with biaxially textured MgO on an amorphous silicon nitride isolation layer. Comparison is made between templates using just 10 nm of ion-beam assisted deposited (IBAD) MgO and substrates with an additional 100 nm of homoepitaxial MgO. Both of these conducting oxide layers exhibited in-plane and out-of-plane texture, on the order of that obtained by the underlying MgO. The SrRuO{sub 3} was c-axis oriented on both substrates, but exhibited a slightly sharper out-of-plane texture when the homoepitaxial MgO layer was included. On the other hand, the LSCO showed only (100) orientation when deposited directly on the IBAD-MgO templates, whereas a significant (110) peak was observed for films on the homoepitaxial MgO. A simple calculation of the distribution of grain boundary angles, assuming a normal distribution of grains, is also presented.

  18. Enhancement of electric-field-induced change of magnetic anisotropy by interface engineering of MgO magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Electric-field-induced modification of magnetic anisotropy is studied using tunnel magnetoresistance of the Co40Fe40B20/ MgO/ Co40Fe40B20 and Co40Fe40B20/ Hf (0.08 nm)/ MgO/ Co40Fe40B20 magnetic tunnel junctions. In both systems, the interfacial perpendicular magnetic anisotropy is increased with increasing electron density at the MgO interface. A quantitative comparison between the two systems reveals that the change of magnetic anisotropy energy with electric field is significantly enhanced in Co40Fe40B20/ Hf/ MgO/ Co40Fe40B20 compared to Co40Fe40B20/ MgO/ Co40Fe40B20. The sub-monolayer Hf insertion at the Co40Fe40B20/MgO interface turns out to be critical to the enhanced electric field control of the magnetic anisotropy, indicating the interface sensitive nature of the effect. (paper)

  19. Reel-to-reel deposition of epitaxial double-sided MgO buffer layers for coated conductors

    Science.gov (United States)

    Xue, Yan; Xiong, Jie; Zhang, Yahui; Zhang, Fei; Zhao, Rui-Peng; Hui, Wang; Wang, Quiling; Cheng, Guo; Zhao, Xiao-Hui; Tao, Bo-Wan

    2016-06-01

    We have successfully employed a double-sided process to deposit MgO buffer layers on both sides of amorphous Y2O3 surface for double-sided YBa2Cu3O7-δ (YBCO) coated conductors (CCs) for the first time, the structure of which is of great prospect to improve the performance and cut the production cost. The biaxial textures of MgO buffer layer are noticeably affected by the ion energy and film thickness, which is demonstrated by X-ray diffraction. The best biaxial texture of double-sided MgO films shows ω-scan of (002) MgO and Φ-scan of (220) MgO yield full width at half maximum values of 4° and 7.8° for one side, respectively, as well as 3.5° and 6.7° for the other side. The subsequent double-sided YBCO films are deposited on the as-prepared MgO template with entire critical current of over 300 A/cm for both sides.

  20. Characterization of Surface Chemical States of a Thick Insulator: Chemical State Imaging on MgO Surface

    Science.gov (United States)

    Yi, Yeonjin; Cho, Sangwan; Noh, Myungkeun; Whang, Chung-Nam; Jeong, Kwangho; Shin, Hyun-Joon

    2005-02-01

    We report a surface characterization tool that can be effectively used to investigate the chemical state and subtle radiation damage on a thick insulator surface. It has been used to examine the MgO surface of a plasma display panel (PDP) consisting of a stack of insulator layers of approximately 51 μm thickness on a 2-mm-thick glass plate. The scanning photoelectron microscopy (SPEM) image of the insulating MgO surface was obtained by using the difference in Au 4f peak shift due to the surface charging at each pixel, where a Au adlayer of approximately 15 {\\AA} thickness was formed on the surface to overcome the serious charging shift of the peak position and the spectral deterioration in the photoelectron spectra. The observed contrast in the SPEM image reveals the chemical modification of the underlying MgO surface induced by the plasma discharge damage. The chemical state analysis of the MgO surface was carried out by comparing the Mg 2p, C 1s and O 1s photoemission spectra collected at each pixel of the SPEM image. We assigned four suboxide phases, MgO, MgCO3, Mg(OH)2 and Mg1+, on the initial MgO surface, where the Mg(OH)2 and Mg1+ phases vanished rapidly as the discharge-induced surface damage began.

  1. Interfacial properties in ultrathin MgO films on TiN(001) surfaces: ab-initio calculations

    International Nuclear Information System (INIS)

    By using ab-initio electronic structure calculations based on the density functional theory, we systematically investigated the interfacial properties of the MgO/TiN(001) system with increasing MgO film thickness from one to three monolayers (ML). Atomic geometries and adhesion characteristics of the MgO/TiN(001) systems in the range of 1- to 3-ML MgO are presented. O-Ti and Mg-N bonds were formed across the interfaces. Our calculated energetics indicate that the interfacial adhesion of the MgO films to the TiN substrates was stronger than that for the metal-oxide systems of MgO/Ag(001) and MgO/Fe(001). An analysis of the electronic properties of the MgO/TiN(001) systems was also performed. Upon the adsorption of the MgO overlayers, the work function of the TiN(001) surface was found to exhibit a significant decrease due to the large interface dipole formed at the interface of this system. Very interestingly, the obtained work functions of 1.89 - 1.96 eV for 1- to 3-ML MgO films on TiN(001) were lower than those for other metal-supported MgO films.

  2. Synthesis of Nanocrystalline MgO Particles by Combustion Followed by Annealing Method Using Hexamine as a Fuel

    Directory of Open Access Journals (Sweden)

    S. Balamurugan

    2014-01-01

    Full Text Available In this work, nanocrystalline MgO particles were prepared through combustion method using magnesium nitrate as oxidizer and hexamine as a fuel. The materials obtained by combustion method were subsequently annealed at 800°C for 3 h to improve the crystallinity and phase purity. The obtained MgO nanomaterials were characterized by powder X-ray diffraction analysis (XRD, infrared (IR spectroscopy, photoluminescence (PL, near-infrared (NIR spectroscopy, and scanning electron microscopy (SEM. The cubic crystal structure with lattice parameter, a = 0.4210(4 nm with average crystalline size of 22 nm, is obtained for the nano-MgO particles. The PL emission spectrum of nanocrystalline MgO materials exhibits three emission peaks at 432, 465, and 495 nm which are due to various structural defects. The SEM results expose the fact that the MgO nanomaterials are seemingly porous and highly agglomerated with fine particles. Owing to the higher reflectance of prepared nanocrystalline MgO, it can be used as NIR reflective pigments. The present results prove that the combustion technique using hexamine can produce the materials with high crystallinity. To the best of our knowledge, this is the first report on the synthesis of nanocrystalline MgO materials by combustion method using hexamine as a fuel.

  3. Transesterification of linoleic and oleic sunflower oils to biodiesel using CaO as a solid base catalyst

    Directory of Open Access Journals (Sweden)

    Predojević Zlatica

    2012-01-01

    Full Text Available The purpose of this work is to characterize biodiesel (i.e. methyl esters, MEs produced from linoleic and oleic sunflower oils (LSO and OSO, respectively by alkali transesterification with methanol and CaO as a heterogeneous catalyst under different reaction parameters. The parameters investigated were the methanol/oil molar ratio (4.5:1, 6:1, 7.5:1, 9:1 and 12:1 and the mass ratio of CaO to oil (2% and 3%. The physical and chemical properties of the feedstocks and MEs, like density at 15oC, kinematic viscosity at 40oC, acid value, iodine value, saponification value, cetane index, fatty acid (methyl ester composition, were determined in order to investigate the effects of LSO and OSO properties and reaction parameters on the product characteristics, yields and purity. The properties of feedstock had decisive effect on the physical and chemical properties of MEs as majority of them did not differ significantly under studied reaction conditions. The MEs produced generally met the criteria required for commercial biodiesel; in fact, the only exception was in the case of iodine value of ME produced from LSO. The product yields only slightly changed with the applied conditions; the highest yield (99.22% was obtained for ME-LSO produced at 6 mol% methanol to oil ratio, while the lowest one (93.20% was for ME-OSO produced under the lowest methanol/oil molar ratio (4.5:1. The applied catalyst amounts had similar influence on the oil conversion to biodiesel. The yields of ME-LSOs were in general somewhat higher than those obtained for ME-OSOs under the same conditions, which was attributed to the influence of the respective feedstocks' acid value and viscosity.

  4. Mechanisms of Vanadium Recovery from Stone Coal by Novel BaCO3/CaO Composite Additive Roasting and Acid Leaching Technology

    Directory of Open Access Journals (Sweden)

    Zhenlei Cai

    2016-03-01

    Full Text Available In this report, the vanadium recovery mechanisms by novel BaCO3/CaO composite additive roasting and acid leaching technology, including the phase transformations and the vanadium leaching kinetics, were studied. The purpose of this manuscript is to realize and improve the vanadium recovery from stone coal using BaCO3/CaO as the composite additive. The results indicated that during the composite additive BaCO3/CaO roasting process, the monoclinic crystalline structure of muscovite (K(Al,V2[Si3AlO10](OH2 was converted into the hexagonal crystalline structure of BaSi4O9 and the tetragonal crystalline structure of Gehlenite (Ca2Al2SiO7, which could, therefore, facilitate the release and extraction of vanadium. Vanadium in leaching residue was probably in the form of vanadate or pyrovanadate of barium and calcium, which were hardly extracted during the sulfuric acid leaching process. The vanadium leaching kinetic analysis indicated that the leaching process was controlled by the diffusion through a product layer. The apparent activation energy could be achieved as 46.51 kJ/mol. The reaction order with respect to the sulfuric acid concentration was 1.1059. The kinetic model of vanadium recovery from stone coal using novel composite additive BaCO3/CaO could be finally established.

  5. Enhancement of exchange bias with crystal orientation in NiFe/CoO and CoO/NiFe bilayers grown on MgO(100) and MgO(111)

    International Nuclear Information System (INIS)

    We present the comparative study of the structural and magnetic properties of the NiFe/CoO and CoO/NiFe bilayers grown on both MgO(111) and MgO(100) substrates by using the ion beam sputtering technique. We observed that crystallographic orientation and crystal quality strongly affected the exchange bias properties of the bilayers. The NiFe layers showed fourfold magnetocrystalline anisotropy when we used MgO(100) substrate and uniaxial anisotropy when we used MgO(111) substrate. When the CoO layer is grown on MgO(111) and MgO(100) substrates as a first layer, instead of the NiFe, the increase of the crystalline quality and stoichiometric CoO phase has been achieved so that the exchange bias field increases by five and three times for NiFe/CoO/MgO(111) and NiFe/CoO/MgO(100) systems, respectively. The blocking temperature significantly increases for NiFe/CoO on MgO(111) and (100) substrates, indicating the increase of the stoichiometric stable Co1O1 phase in the exchange-biased system. The magnitude of the exchange bias field is 800 Oe at 10 K for NiFe/CoO/MgO(111) and more than two times as compared to that of NiFe/CoO/MgO(100). This high exchange bias value observed for NiFe/CoO/MgO(111) was explained with the uncompensated spins in CoO(111) surface. We also carried out training effect measurements to observe the durability of the exchange bias for technological applications. - Highlights: • This paper analyses magnetization dynamic of exchange biased of NiFe/CoO thin films. • Exchange bias is enhanced by crystal orientation and quallity. • High exchange bias value observed due to the uncompensated spins in CoO(111) surface

  6. Influence of CaO content on viscosity of molten CaO-Al2 O3-SiO2 system

    Directory of Open Access Journals (Sweden)

    L. Řeháčková

    2013-01-01

    Full Text Available Purpose: The objective of this work is experimental determination of temperature dependences of viscosity of the molten CaO-Al2O3-SiO2 system and assessment of impact of CaO on the viscosity of this system.Design/methodology/approach: The ternary oxide system CaO-Al2O3-SiO2, which represents a simplified basis of the casting powder, was chosen for the experiment. Dependencies of viscosity on the concentration of CaO and on the temperature were determined experimentally. For this purpose were prepared a concentration series with additions of 3, 6, 9, 12 and 15 wt.% of calcium oxide. Experimental measurements of viscosity was performed with use of the high-temperature viscometer Anton Paar FRS 1600.Findings: Viscosity of the studied systems decreases exponentially with the increasing temperature. Viscosity decreases with the increasing addition of CaO. Viscosity reaches its minimum value of 0.447 Pa.s (at T = 1723 K at the basicity of CaO/SiO2 = 1.13. Viscosity increases with the further addition of CaO (CaO/SiO2 > 1.2. Influence of addition of CaO is more pronounced at higher temperatures.Research limitations/implications: Viscosity in molten oxide system is determined by the internal structure. Exact clarification of the change of structure of the oxide system caused by the increased content of CaO requires additional analyses, such as Fourier transformation infrared spectra and Raman spectra.Practical implications: The choice of an optimum slag mode influences not only the main metallurgical processes, but also the values of technical-economic indicators of the whole steelmaking process. Viscosity is an important factor affecting the service properties of slags, as it plays an important role in the area of mass transfer at chemical reactions in metallurgical processes.Originality/value: The viscosities of CaO-Al2O3-SiO2 system were measured under conditions of CaO/SiO2 = 0.78-1.44, 47.20-35.98 wt.% SiO2, 36.90-51.90 wt.% CaO and 15.90-12.12 wt

  7. Elucidating the mechanism of Cr(VI) formation upon the interaction with metal oxides during coal oxy-fuel combustion.

    Science.gov (United States)

    Chen, Juan; Jiao, Facun; Zhang, Lian; Yao, Hong; Ninomiya, Yoshihiko

    2013-10-15

    The thermodynamics underpinning the interaction of Cr-bearing species with basic metal oxides, i.e. K2O, Fe2O3, MgO and CaO, during the air and oxy-fuel combustion of coal have been examined. The synchrotron-based X-ray adsorption near-edge spectroscopy (XANES) was used for Cr speciation. For the oxides tested, Cr(VI) formation is dominated by the reduction potential of the metals. The oxides of Ca(2+) with high reduction potential favored the oxidation of Cr(III), same for K(+). The other two basic metals, Fe2O3 and MgO with lower reduction potentials reacted with Cr(III) to form the corresponding chromites at the temperatures above 600°C. Coal combustion experiments in drop-tube furnace have confirmed the rapid capture of Cr vapors, either trivalent or hexavalent, by CaO into solid ash. The existence of HCl in flue gas favored the vaporization of Cr as CrO2Cl2, which was in turn captured by CaO into chromate. Both Fe2O3 and MgO exhibited less capability on scavenging the Cr(VI) vapor. Particularly, MgO alone exhibited a low capability for capturing the vaporized Cr(III) vapors. However, its co-existence with CaO in the furnace inhibited the Cr(VI) formation. This is beneficial for minimizing the toxicity of Cr in the coal combustion-derived fly ash. PMID:23969010

  8. Significance of the structural properties of CaO catalyst in the production of biodiesel: An effect on the reduction of greenhouse gases emission

    Directory of Open Access Journals (Sweden)

    Ljupković Radomir B.

    2014-01-01

    Full Text Available The influence of the physicochemical properties of a series of CaO catalysts activated at different temperatures on the biodiesel production was investigated. These catalysts show dissimilar yields in the transesterification of triglycerides with methanol. We have found significant relationships between structural properties (the type of the pore system, the typical CaO crystal phase and the sizes of crystallites (up to 25 nm, the minimal weight percentage of CaO phase, the total surface basicity and potential existence of two types of basic active sites of CaO prepared and activated by means of thermal treatment at highest temperature and catalytic efficiency. Benefits of this catalyst are short contact time, standard operating temperature and atmospheric conditions, relatively low molar ratios and small catalyst loading. These all together resulted in a very high biodiesel yield of high purity. The properties of different biodiesel (obtained with the use of the prepared CaO catalyst blends with different diesel and biodiesel ratios indicate that the higher the fraction of biodiesel fuel the better the achieved fuel properties according to the EU standards. A significant reduction of CO2 and CO emissions and only a negligible NOx increase occurred when blends with an increased biodiesel portion was used. The use of biodiesel derived blends, and the eventual complete replacement of fossil fuels with biodiesel as a renewable, alternative fuel for diesel engines, would greatly contribute to the reduction of greenhouse gases emissions. [Projekat Ministarstva nauke Republike Srbije, br. ON 172061 i TR 34008

  9. Dip coated 12CaO.7Al2O3 thin films through sol-gel process using metal alkoxide

    International Nuclear Information System (INIS)

    Transparent nanostructured 12CaO.7Al2O3 thin films with cubic structure have been prepared on soda lime glass substrates via the sol-gel dip coating using the precursor sol solution at low temperature. The structural, compositional, morphological and optical properties of the 12CaO.7Al2O3 films and powder were studied using X-ray diffractometry (XRD), X-ray photoelectron spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy. Optical properties of 12CaO.7Al2O3 films have been investigated using UV-visible spectroscopy. Two different precursor sols were prepared using calcium-2-ethyl hexonate and aluminium isopropoxide as precursor materials in isopropanol and ethylene glycol monomethyl ether solvents. Dip coated gel like films were dried at 120 oC for 15 min and subsequently heat-treated at 450 oC for 1 h in air atmosphere. The influence of films thickness and optical transparency with use of different solvent and sol concentration on microstructure of the films were established. In addition, XRD patterns revealed that 12CaO.7Al2O3 films have been composed of cubic phase. SEM observations exhibited that the films structure becomes more homogeneous using isopropanol as compared to ethylene glycol monomethyl ether solvent. The 12CaO.7Al2O3 films prepared using 2 (wt.%) sol in isopropanol had high transparency nearly 88% in wide visible range with maximum of 90% at 600 nm wavelength.

  10. (2 0 0)-Texture and microstructure of MgO films by rf-magnetron sputtering in Ar plus N2 atmosphere

    International Nuclear Information System (INIS)

    Intensity of the (2 0 0) peak in the X-ray diffraction pattern of the MgO film increases as N2 is added to Ar gas during MgO deposition. The optimum flow rate ratio of N2 to Ar in order to obtain maximum intensity of the MgO (2 0 0) peak is 2:5. As introducing N2 gas, no residual nitrogen atoms are found in the MgO films, which are confirmed by AES and ESCA analysis. On the other hand, the TEM dark field image shows that the average grain size of MgO film increases with increasing the flow rate ratio of N2 to Ar. This is due to that the deposition rate of MgO film is decreased with increasing the flow rate ratio of N2 to Ar.

  11. Stabilization and solidification of electric arc furnace dust originating from steel industry by using low grade MgO

    Directory of Open Access Journals (Sweden)

    Bayraktar Ahmet Can

    2015-12-01

    Full Text Available In this study, solidification/stabilization (S/S of electric arc furnace dust (EAFD which is generated during the production of steel from scrap metals and classified as hazardous waste were investigated by using different ratios of cement and low grade MgO (LG MgO as binding agents. Type I PC 42.5 R portland cement and LG MgO which contains 70–80% MgO were used. S/S blocks that contain different ratios of binding agents which have 1/0.5 – 1/1 – 1/2 – 1/3 – 1/4 – 1/5 cement/LG MgO ratio and S/S blocks which contain only cement and no LG MgO agents were prepared. These blocks, which contain 3 different waste ratios according to weight, 20%, 30% and 40% respectively, were produced and exposed to 28-day water purification. At the end of the purification process, S/S blocks were extracted using TCLP (Toxicity Characteristic Leaching Procedure tests in order to determine the leaching behavior of Zn, Pb, and Cd in S/S blocks. By the end of this study, it was concluded that the recovery of EAFD is possible and applicable by immobilization. The findings of the study concluded that environmental performances or structural properties of blocks contain 30% waste by weight are suitable. This method is a proper one for recovering and treatment of EAFD with mixture of cement and LG MgO.

  12. X-Ray Diffraction Microstructural Analysis of Bimodal-Size-Distribution MgO Nanopowders

    Science.gov (United States)

    Pratapa, Suminar; Hartono, Budi

    2010-01-01

    Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500, 800 and 1200° C for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then carefully blended in air to give the presumably strain-free, bimodal-size-distribution MgO nanopowder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (Dv) of 29(1) nm, 36(1) and 185(0) nm for the 500, 800 and 1200° C data respectively with the nanometric powder displays slightly narrower crystallite size distribution character, indicated by lognormal dispersion parameter (σ) of 0.22 as compared to 0.18 for the sub-nanometric 1200° C powder. The mixture exhibits relatively more asymmetric peak broadening. By analysing the x-ray diffraction data of the latter specimen by using the single phase approach the results obtained was not according to experimental finding. Introducing two phase models for the `double-phase' 500-1200 mixture to accommodate the bimodal-size-distribution characteristics give Dv = 34(2) and σ = 0.10 for the `nanometric phase' and Dv = 363(0) and σ = 1.38 for the `sub-nanometric phase'.

  13. Charge dynamics of MgO single crystals subjected to KeV electron irradiation

    Science.gov (United States)

    Boughariou, A.; Blaise, G.; Braga, D.; Kallel, A.

    2004-04-01

    A scanning electron microscope has been equipped to study the fundamental aspects of charge trapping in insulating materials, by measuring the secondary electron emission (SEE) yield σ with a high precision (a few percent), as a function of energy, electron current density, and dose. The intrinsic secondary electron emission yield σ0 of uncharged MgO single crystals annealed at 1000 °C, 2 h, has been studied at four energies 1.1, 5, 15, and 30 keV on three different crystal orientations (100), (110), and (111). At low energies (1.1 and 5 keV) σ0 depends on the crystalline orientation wheras at high energies (30 keV) no differentiation occurs. It is shown that the value of the second crossover energy E2, for which the intrinsic SEE yield σ0=1, is extremely delicate to measure with precision. It is about 15 keV±500 eV for the (100) orientation, 13.5 keV±500 eV for the (110), and 18.5 keV±500 eV for the (111) one. At low current density J⩽105 pA/cm2, the variation of σ with the injected dose makes possible the observation of a self-regulated regime characterized by a steady value of the SEE yield σst=1. At low energies 1.1 and 5 keV, there is no current density effects in MgO, but at high energies ≈30 keV, apparent current density effects come from a bad collect of secondary electrons, due to very high negative surface potential. At 30 keV energy, an intense erratic electron exoemission was observed on the MgO (110) orientation annealed at 1500 °C. This phenomenon is the result of a disruptive process similar to flashover, which takes place at the surface of the material.

  14. X-ray diffraction microstructural analysis of bimodal size distribution MgO nano powder

    International Nuclear Information System (INIS)

    Investigation on the characteristics of x-ray diffraction data for MgO powdered mixture of nano and sub-nano particles has been carried out to reveal the crystallite-size-related microstructural information. The MgO powders were prepared by co-precipitation method followed by heat treatment at 500 degree Celsius and 1200 degree Celsius for 1 hour, being the difference in the temperature was to obtain two powders with distinct crystallite size and size-distribution. The powders were then blended in air to give the presumably bimodal-size- distribution MgO nano powder. High-quality laboratory X-ray diffraction data for the powders were collected and then analysed using Rietveld-based MAUD software using the lognormal size distribution. Results show that the single-mode powders exhibit spherical crystallite size (R) of 20(1) nm and 160(1) nm for the 500 degree Celsius and 1200 degree Celsius data respectively with the nano metric powder displays narrower crystallite size distribution character, indicated by lognormal dispersion parameter of 0.21 as compared to 0.01 for the sub-nano metric powder. The mixture exhibits relatively more asymmetric peak broadening. Analysing the x-ray diffraction data for the latter specimen using single phase approach give unrealistic results. Introducing two phase models for the double-phase mixture to accommodate the bimodal-size-distribution characteristics give R = 100(6) and σ = 0.62 for the nano metric phase and R = 170(5) and σ= 0.12 for the σ sub-nano metric phase. (author)

  15. Water dissociation and water-gas shift energetics on MgO, MgO/Ag and Au/MgO/Ag surfaces

    OpenAIRE

    Nevalaita, Janne

    2011-01-01

    Water dissociation and the energetics of the WGS reaction on a bulk MgO, an Ag supported MgO thin film and Au/MgO/Ag surfaces is studied based on the density functional theory. The literature results for water splitting on MgO and MgO/Ag surfaces with a step type defect are repeated and further analysis on the origin of the energetically favored dissociative water adsorption are made. The reactivity towards water dissociation on the stepped MgO and MgO/Ag surfaces is attribu...

  16. Periodic DFT study of acidic trace atmospheric gas molecule adsorption on Ca and Fe doped MgO (001) surface basic sites

    OpenAIRE

    Baltrusaitis, Jonas; Hatch, Courtney; Orlando, Roberto

    2012-01-01

    The electronic properties of undoped and Ca or Fe doped MgO (001) surfaces, as well as their propensity towards atmospheric acidic gas (CO2, SO2 and NO2) uptake was investigated with an emphasis on gas adsorption on the basic MgO oxygen surface sites, Osurf, using periodic Density Functional Theory (DFT) calculations. Adsorption energy calculations show that MgO doping will provide stronger interactions of the adsorbate with the Osurf sites than the undoped MgO for a given adsorbate molecule....

  17. The role of exposed silver in CO oxidation over MgO(0 0 1)/Ag(0 0 1) thin films

    OpenAIRE

    Ringleb, F.; Fujimori, Y.; Brown, M; Kaden, W.; Calaza, F.; Kuhlenbeck, H.; Sterrer, M.; Freund, H

    2015-01-01

    The reactivity of MgO(0 0 1) films deposited on Ag(0 0 1) and Mo(0 0 1) in CO oxidation as a function of oxide film thickness was investigated experimentally at ambient pressure reaction conditions. MgO films grown on Mo(0 0 1) were found to be inactive in CO oxidation, whereas activity enhancement with decreasing oxide film thickness was observed for MgO(0 0 1)/Ag(0 0 1). In situ infrared and post-reaction X-ray photoemission data showed that ultra-thin MgO films interact much more strongly ...

  18. Extrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    OpenAIRE

    D. Kadri; S. Hiadsi; Hamzaoui, S.

    2007-01-01

    MgO single crystal sample previously irradiated with ultraviolet light (UV) 4.8 eV has been studied using thermoluminescence (TL) technique in the temperature range 170-500�K, in this study, we were mainly interested in the extrinsic defects (impurities), these impurities are localised in four distinct regions, Cr3+ is assigned to the first region 680-760 nm, in the second region 465-500 nm we find Ni2+, Fe3+ is localised in the third region 310-375 nm and lastly the Ca2+ and K+ have been fou...

  19. Extrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    Directory of Open Access Journals (Sweden)

    D. Kadri

    2007-01-01

    Full Text Available MgO single crystal sample previously irradiated with ultraviolet light (UV 4.8 eV has been studied using thermoluminescence (TL technique in the temperature range 170-500�K, in this study, we were mainly interested in the extrinsic defects (impurities, these impurities are localised in four distinct regions, Cr3+ is assigned to the first region 680-760 nm, in the second region 465-500 nm we find Ni2+, Fe3+ is localised in the third region 310-375 nm and lastly the Ca2+ and K+ have been found to emit in the 180-260 nm region.

  20. Epitaxial MgO layer for low-resistance and coupling-free magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Epitaxially grown magnetic tunnel junctions MgO(100)/Fe/MgO/Fe/Co/Pd have been elaborated by molecular beam epitaxy, with insulating layer thickness down to 0.8 nm. The continuity of this layer was checked at different spatial scales by means of morphological (high resolution transmission electronic microscopy), electric (local impedance), and magnetic (magnetoresistance and hysteresis loop) measurements. These junctions show a low resistance (4 kΩ μm2), tunnel magnetoresistance up to 17%, and a very small interlayer magnetic coupling

  1. Simulation of YBa2Cu3O7/MgO surface growth

    International Nuclear Information System (INIS)

    For surface growth simulation of YBa2Cu3O7 on MgO substrate, binding energies between each two different Y, Ba, Cu, O, and Mg atoms were calculated by ab initio pseudopotential density functional theory approach. Then, simulation of YBa2Cu3O7 growth was performed by a simple two dimensional model based on the ballistic aggregation of hard discs. By increasing the substrate temperature, the atomic layers distribution is more condensed and the nanometric surface roughness decreases. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Structures of pure and Ca-segregated MgO (001) surfaces

    CERN Document Server

    Yanfa, Y; Pennycook, S J; Pantelides, S T

    1999-01-01

    The structures of pure and Ca-segregated MgO (001) surfaces have been studied using first-principles density functional theory. The relaxation and rumpling for the pure surface are found to be 0.48 and 1.62, respectively. Ca segregation significantly modifies the surface structure. The surface-segregated Ca atoms protrude outwards owing to the size mismatch between Ca and Mg. Consequently, their nearest neighbor oxygen atoms are pulled up. The value of the protrusion of Ca atoms is strongly dependent on the Ca coverage of the surface. (18 refs).

  3. In situ investigation of the mobility of small gold clusters on cleaved MgO surfaces

    Science.gov (United States)

    Metois, J. J.; Heinemann, K.; Poppa, H.

    1976-01-01

    The mobility of small clusters of gold (about 10 A in diameter) on electron-beam-cleaved MgO surfaces was studied by in situ transmission electron microscopy under controlled vacuum and temperature conditions. During the first 10 min following a deposition at room temperature, over 10 per cent of the crystallites moved over short distances (about 20 A) discontinuously, with a velocity greater than 150 A/sec. Eighty per cent of the mobility events were characterized by the avoidance of proximity of other crystallites, and this was tentatively explained as the result of repulsive elastic forces between the interacting crystallites.

  4. The emission of atoms and molecules accompanying fracture of single-crystal MgO

    Science.gov (United States)

    Dickinson, J. T.; Jensen, L. C.; Mckay, M. R.; Freund, F.

    1986-01-01

    The emission of particles due to deformation and fracture of materials has been investigated. The emission of electrons (exoelectron emission), ions, neutral species, photons (triboluminescence), as well as long wavelength electromagnetic radiation was observed; collectively these emissions are referred to as fractoemission. This paper describes measurements of the neutral emission accompanying the fracture of single-crystal MgO. Masses detected are tentatively assigned to the emission of H2, CH4, H2O, CO, O2, CO2, and atomic Mg. Other hydrocarbons are also observed. The time dependencies of some of these emissions relative to fracture are presented for two different loading conditions.

  5. Heteroepitaxial growth of TiN film on MgO (100) by reactive magnetron sputtering

    OpenAIRE

    Chen, Wei-Chun; Peng, Chun-Yen; Chang, Li

    2014-01-01

    TiN thin films were deposited on MgO (100) substrates at different substrate temperatures using rf sputtering with Ar/N2 ratio of about 10. At 700°C, the growth rate of TiN was approximately 0.05 μm/h. The structural and electrical properties of TiN thin films were characterized with x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall measurements. For all deposition conditions, XRD results show that the ...

  6. Oscillatory energetics of flat Ag films on MgO(001)

    International Nuclear Information System (INIS)

    The energetics and electronic structures of flat Ag films on the MgO(001) substrate are studied by first-principles density-functional calculations. An oscillatory variation of the film energetics showing the existence of multiple magic thicknesses for smooth growth is found. This oscillatory behavior correlates well with the quantum-well states, which themselves vary with the film thickness. The results demonstrate the importance of the confined motion of the conduction electrons in stabilizing epitaxial metal films, as emphasized in a recent ''electronic growth'' model

  7. Large-area thin self-supporting carbon foils with MgO coatings

    CERN Document Server

    Stolarz, A

    2002-01-01

    Large area self-supporting carbon foils in the thickness of range of 8-22 mu g/cm sup 2 , coated with approximately 4 mu g/cm sup 2 MgO have been prepared by e-gun evaporation. They were mounted on frames with apertures of 130 cm sup 2. Problems related to the parting agent preparation, floating procedure, and mounting onto frames are discussed. Special precautions necessary to avoid damage during foil drying, storage and transportation are suggested.

  8. Thermally stimulated currents in ZrO2:MgO

    International Nuclear Information System (INIS)

    Thermally Stimulated Depolarization Current measurements between 100 K and 350 K have been performed in ZrO2:MgO ceramic samples to discriminate the several Kinds of polarization (orientational and interfacial polarization, and extrinsic and intrinsic space charge effects) to allow for the use of the technique in the study of solid solution formation in partially stabilized zirconia. The samples were prepared by conventional ceramic processing methods. Different electrode materials have been used: colloidal graphite, silver, gold, and also insulating electrodes (e.g. mylar foils). The current spectra obtained are strongly dependent upon the electrode material showing the presence of spacial charge phenomenon in these ceramics. (Author)

  9. Thermally stimulated currents in ZrO2:MgO

    International Nuclear Information System (INIS)

    Thermally Stimulated Depolarization Current measurements between 100 K and 350 K have been performed in ZrO2:MgO ceramic samples to discriminate the several kinds of polarization (orientational and interfacial polarization, and extrinsic and intrinsic space charge effects) to allow for the use of the technique in the study of solid solution formation in partially stabilized zirconia. The samples were prepared by conventional ceramic processing methods. Different electrode materials have been used: colloidal graphite, silver, gold, and also insulating electrodes (e.g. mylar foils). The current spectra obtained are strongly dependent upon the electrode material showing the presence of spacial charge phenomenon in these ceramics. (Author)

  10. Low-pressure ETEM Studies of Au assisted MgO Nanorod Growth

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Duchstein, Linus Daniel Leonhard; Ming, Lin; Damsgaard, Christian Danvad; Hansen, Thomas Willum

    Over the past few decades, there has been an increasing interest in the use of supported nanoparticles in applications ranging from drug delivery to catalysis. The functionality of such nanoparticles is to a large extent controlled by their shape, exposed surface facets and interaction with the...... catalyst nanoparticles in a controlled gas atmosphere, in order to elucidate the mobility of Au surface atoms and the configuration of the Au/MgO interface. The particles are synthesized by depositing a thin layer of Au onto MgO smoke particles. The Au agglomerates into particles that are a few nanometers...

  11. Production of Sİ3N4 AddedY2O3MgO

    OpenAIRE

    Karakuş, Nuray; TOPLAN, H. Özkan

    2014-01-01

    Silicon nitride (Si3N4) ceramics have common application areas due to their marvelous thermomechanic properties. These materials are used heavily in cutting tools, ball bearings, motor valves and the other wear resistant tools. The microstructural growth of Si3N4 ceramic is controlled by three different parameters; properties of initial Si3N4 powders, compositions of sintering reagents and sintering conditions. Generally, MgO, Y2O3, Al2O3 and rare earth oxides are used as sintering additives....

  12. Desulfurization and oxidation behavior of ultra-fine CaO particles prepared from brown coal; Kattan wo mochiite choseishita CaO chobiryushi no datsuryu tokusei to sanka tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Benjamin, G.; Roman, M.; Yamazaki, Y.; Abe, H.; Harano, Y.; Takarada, Y. [Gunma University, Gunma (Japan). Faculty of Engineering

    1996-10-28

    The effect of reaction temperature and oxygen concentration on the desulfurization and oxidation behavior of ion-exchanged brown coal by Ca as new desulfurizing agent was studied. In experiment, Yallourn coal was used for ion- exchange, and limestone produced in Tochigi prefecture was also used for comparative study. Ca-exchanged brown coal was prepared by agitating coal in Ca(OH)2 slurry for 24 hours. The desulfurization behavior of a desulfurizing agent was obtained by measuring H2S and sulfur compounds in outlet gas of a reactor, and the oxidation behavior by measuring SO2 emission in outlet gas after oxidation reaction. As the experimental result, CaO produced from Ca-exchanged brown coal offered the extremely high activity to desulfurization reaction in a temperature range of 850-950{degree}C as compared with limestone. Although the oxidation behavior was dependent on oxidation temperature and oxygen concentration, CaS obtained from Ca-exchanged brown coal was more rapidly converted to CaSO4 than limestone. 3 refs., 8 figs., 2 tabs.

  13. Effect of substrate temperature on the texture of MgO films grown by ion beam assisted deposition

    International Nuclear Information System (INIS)

    In this paper, the role of substrate temperature in the crystalline texture of MgO films grown by ion beam assisted deposition (IBAD) is investigated. This study reveals that the best in-plane alignment for MgO films grown on Y2O3/Si is obtained at ∼25 deg. C. At this temperature, MgO films with an in-plane orientation distribution as low as 3.70 full width at half maximum (FWHM) have been attained. MgO films deposited at temperatures higher than 100 deg. C have broad in-plane alignment. Although the deposition at the lowest temperature (-150 deg. C) did not improve the in-plane texture, the acceptable deviation from the optimum ion to molecule ratio for achieving biaxially textured films was the largest. As a trend, the acceptable ion to molecule deviation decreases with increasing substrate temperature. This study is especially important for continuous IBAD MgO depositions where less restrictive conditions are desired

  14. Effect of substrate temperature on the texture of MgO films grown by ion beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Stan, Liliana; Arendt, Paul N; DePaula, Raymond F; Usov, Igor O; Groves, James R [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2006-04-15

    In this paper, the role of substrate temperature in the crystalline texture of MgO films grown by ion beam assisted deposition (IBAD) is investigated. This study reveals that the best in-plane alignment for MgO films grown on Y{sub 2}O{sub 3}/Si is obtained at {approx}25 deg. C. At this temperature, MgO films with an in-plane orientation distribution as low as 3.7{sup 0} full width at half maximum (FWHM) have been attained. MgO films deposited at temperatures higher than 100 deg. C have broad in-plane alignment. Although the deposition at the lowest temperature (-150 deg. C) did not improve the in-plane texture, the acceptable deviation from the optimum ion to molecule ratio for achieving biaxially textured films was the largest. As a trend, the acceptable ion to molecule deviation decreases with increasing substrate temperature. This study is especially important for continuous IBAD MgO depositions where less restrictive conditions are desired.

  15. Magnetic properties of MgN and MgC films on MgO(001) surfaces

    International Nuclear Information System (INIS)

    Using the full potential linearized augmented plane wave (FLAPW) method, we have explored the magnetic properties of one monolayer (ML) of MgN and MgC films on MgO(001) surfaces. In addition, the influence of a MgO capping layer on the magnetic states of MgC and MgN films has been investigated. We observed that both MgC/MgO(001) and MgN/MgO(001) display ferromagnetic (FM) state. Interestingly, we find that both free standing MgN film and MgN/MgO(001) systems display half metallic feature. The calculated magnetic moments of C and N in MgC/MgO(001) and MgN/MgO(001) are 0.3 μB and 0.57 μB, respectively. The essential magnetic properties of both systems are unchanged even in the presence of a MgO capping layer. In particular, the half metallic feature in MgN/MgO(001) is still maintained in both the MgN/MgO(001) and the MgO(1 ML)/MgN/MgO(001) systems. The adsorption energy calculations indicate that the MgC layer is physisorbed on MgO(001), while the MgN layer is chemisorbed. Due to the rigid half metallic feature and the character of adsorption, the MgN/MgO(001) can be utilized for potential spintronics purposes.

  16. Analysis of Waste Isolation Pilot Plan (WIPP) Underground and MGO Samples by the Savannah River National Laboratory (SRNL)

    Energy Technology Data Exchange (ETDEWEB)

    Young, J. [Savannah River Site (SRS), Aiken, SC (United States); Ajo, H. [Savannah River Site (SRS), Aiken, SC (United States); Brown, L. [Savannah River Site (SRS), Aiken, SC (United States); Coleman, C. [Savannah River Site (SRS), Aiken, SC (United States); Crump, S. [Savannah River Site (SRS), Aiken, SC (United States); Diprete, C. [Savannah River Site (SRS), Aiken, SC (United States); Diprete, D. [Savannah River Site (SRS), Aiken, SC (United States); Ekechukwu, A. [Savannah River Site (SRS), Aiken, SC (United States); Gregory, C. [Savannah River Site (SRS), Aiken, SC (United States); Jones, M. [Savannah River Site (SRS), Aiken, SC (United States); Missimer, D. [Savannah River Site (SRS), Aiken, SC (United States); O' Rourke, P. [Savannah River Site (SRS), Aiken, SC (United States); White, T. [Savannah River Site (SRS), Aiken, SC (United States)

    2014-12-31

    Analysis of the recent WIPP samples are summarized in this report; WIPP Cam Filters 4, 6, 9 (3, 7, 11 were analyzed with FAS-118 in a separate campaign); WIPP Drum Lip R16 C4; WIPP Standard Waste Box R15 C5; WIPP MgO R16 C2; WIPP MgO R16 C4; WIPP MgO R16 C6; LANL swipes of parent drum; LANL parent drum debris; LANL parent drum; IAEA Swipe; Unused “undeployed” Swheat; Unused “undeployed” MgO; and Masselin cloth “smears”. Analysis showed that the MgO samples were very pure with low carbonate and water content. Other samples showed the expected dominant presence of Mg, Na and Pb. Parent drum debris sample was mildly acidic. Interpretation of results is not provided in this document, but rather to present and preserve the analytical work that was performed. The WIPP Technical Analysis Team is responsible for result interpretation which will be written separately.

  17. Magneto-optical characterization of single crystalline Co2FeAl0.4Si0.6 thin films on MgO(1 0 0) substrates with Cr and MgO seed layers

    International Nuclear Information System (INIS)

    We report on the experimental investigation of the influence of a seed layer on the magnetic properties of the full-Heusler alloy Co2FeAl0.4Si0.6 (CFAS). The studied magnetic films are grown epitaxially on MgO (1 0 0) substrates with Cr and/or MgO seed layers. By employing magneto-optical Kerr effect magnetometry we show that magnetic anisotropy can be tuned by choosing the proper seed layer. The results on CFAS show an overall uniaxial anisotropy plus a biaxial contribution which depends on the seed layer. In addition, if grown on MgO, a sharp increase in the coercive field HC at a series of angles symmetric with respect to the easy axis is present. Scanning Kerr-microscope imaging is performed during the magnetization reversal process in order to reveal the type of magnetic domain formation taking place at these angles. (paper)

  18. Discussion of "use of solid electrolyte galvanic cells to determine the activity of CaO in the $CaO-ZrO_2$ system and standard Gibbs free energies of formation of $CaZrO_3$ from CaO and $ZrO_2$"

    OpenAIRE

    Jacob, KT

    1997-01-01

    In a recent article, Tanabe and Nagata[1] have used Ca4P2O9 (4CaOzP2O5) as a solid electrolyte in a cell designed to measure the activity of CaO in the system CaOZrO 2 between 1572 and 1877 K. The article is interesting, not only because of new data obtained on an important system, but also because the authors have tried to extend the current experimental capabilities for measuring the activity of CaO to higher temperatures than is possible with the well-established CaF2 solid electrolyte.[2,...

  19. Genetic variants of Cao Bang hantavirus in the Chinese mole shrew (Anourosorex squamipes) and Taiwanese mole shrew (Anourosorex yamashinai).

    Science.gov (United States)

    Gu, Se Hun; Arai, Satoru; Yu, Hon-Tsen; Lim, Burton K; Kang, Hae Ji; Yanagihara, Richard

    2016-06-01

    To determine the genetic diversity and geographic distribution of Cao Bang virus (CBNV) and to ascertain the existence of CBNV-related hantaviruses, natural history collections of archival tissues from Chinese mole shrews (Anourosorex squamipes) and Taiwanese mole shrews (Anourosorex yamashinai), captured in Guizho Province, People's Republic of China, and in Nantou County, Taiwan, in 2006 and 1989, respectively, were analyzed for hantavirus RNA by RT-PCR. Pair-wise alignment and comparison of the S-, M- and L-segment sequences indicated CBNV in two of five Chinese mole shrews and a previously unrecognized hantavirus, named Xinyi virus (XYIV), in seven of 15 Taiwanese mole shrews. XYIV was closely related to CBNV in Vietnam and China, as well as to Lianghe virus (LHEV), recently reported as a distinct hantavirus species in Chinese mole shrews from Yunnan Province in China. Phylogenetic analyses, using maximum-likelihood and Bayesian methods, showed that XYIV shared a common ancestry with CBNV and LHEV, in keeping with the evolutionary relationship between Anourosorex mole shrews. Until such time that tissue culture isolates of CBNV, LHEV and XYIV can be fully analyzed, XYIV and LHEV should be regarded as genetic variants, or genotypes, of CBNV. PMID:26921799

  20. Heat recovery from a thermal energy storage based on the Ca(OH)2/CaO cycle

    International Nuclear Information System (INIS)

    Thermal energy storage is very important in many applications related to the use of waste heat from industrial processes, renewable energies or from other sources. Thermochemical storage is very interesting for long-term storage as it can be carried out at room temperature with no energy losses. Dehydration/hydration cycle of Ca(OH)2/CaO has been applied for thermal energy storage in two types of reactors. One of them was a prototype designed by the authors, and in the other type conventional laboratory glassware was used. Parameters such as specific heats, reaction rate and enthalpy, mass losses and heat release were monitored during cycles. Although in the hydration step water is normally added in vapour phase, liquid water, at 0 deg. C has been used in these experiences. Results indicated that the energy storage system performance showed no significant differences, when we compared several hydration/dehydration cycles. The selected chemical reaction did not exhibit a complete reversibility because complete Ca(OH)2 dehydration, was not achieved. However the system could be used satisfactorily along 20 cycles at least. Heat recovery experiments showed general system behaviour during the hydration step in both types of reactors. The designed prototype was more efficient in this step. Main conclusions suggested carrying out one complete cycle at a higher dehydration temperature to recover total system reversibility. A modification of the prototype design trying to enhance heat transfer from the Ca(OH)2 bed could also be proposed

  1. CO{sub 2} capture capacity of CaO in long series of carbonation/calcination cycles

    Energy Technology Data Exchange (ETDEWEB)

    Grasa, G.S.; Abanades, J.C. [CSIC, Zaragoza (Spain)

    2006-12-20

    Calcium oxide can be an effective sorbent to separate CO{sub 2} at high temperatures. When coupled with a calcination step to produce pure CO{sub 2}, the carbonation reaction is the basis for several high-temperature CO{sub 2} capture systems. The evolution with cycling of the capture capacity of CaO derived from natural limestones is experimentally investigated in this work. Long series of carbonation/calcination cycles (up to 500) varying different variables affecting sorbent capacity have been tested in a thermogravimetric apparatus. Calcination temperatures above T > 950{sup o}C and very long calcination times accelerate the decay in sorption capacity, while other variables have a comparatively modest effect on the overall sorbent performance. A residual conversion of about 7-8% that remains constant after many hundreds of cycles and that seems insensitive to process conditions has been found. This residual conversion makes very attractive the carbonation/calcination cycle, by reducing (or even eliminating) sorbent purge rates in the system. A semiempirical equation has been proposed to describe sorbent conversion with the number of cycles based on these new long data series.

  2. ¿Caos en el electrocardiograma de estudiantes con miedo a volar? Un análisis de no linealidad

    Directory of Open Access Journals (Sweden)

    Jordi Llabrés

    2005-01-01

    Full Text Available La Teoría del Caos proporciona una nueva forma de analizar las respuestas psicofisiológicas asociadas a los trastornos de ansiedad. Pero para poder aplicar los métodos de análisis no lineal de esta relativamente reciente teoría, primero es necesario comprobar la existencia de algún tipo de no linealidad que justifique su uso. En este estudio experimental se analiza, mediante el procedimiento de los datos vicarios, la no linealidad de las señales generadas por el sistema cardiovascular (ECG de estudiantes con y sin miedo a volar, en diferentes condiciones de estimulación. Los errores de predicción de las series vicarias fueron siempre mayores que los de las correspondientes series empíricas (p < 0,05, demostrándose así que las señales ECG, en todos los sujetos y en todas las condiciones, presentan propiedades no lineales y que por tanto resulta adecuado analizarlas desde planteamientos no lineales para obtener conocimiento acerca de su complejidad, entropía, regularidad, etc.

  3. Sensitive Evaluation on Early Cracking Tendency of Concrete with Inclusion of Light-burnt MgO

    Institute of Scientific and Technical Information of China (English)

    CHEN Xia; YANG Huaquan; Zhou Shihua; LI Wenwei

    2011-01-01

    The advanced temperature and stress test machine was introduced to determine the early cracking tendency of concrete with inclusion of light-burnt MgO under full restraint by tracking the development of thermal,physical and deformation properties.Results showed that light-burnt MgO being incorporated ranging between 4 wt% and 6 wt% of cementitious materials was beneficial to increase the maximum compressive stress and cracking stress of concrete by 0.37 MPa and 0.2 MPa on average respectively.The second zero stress temperature was reduced by 11.4 ℃ and the maximum temperature was slightly reduced while cracking thermal impact was significantly enhanced from 59.8 ℃ to 66.2 ℃.Sensitive anti-cracking coefficient F was forwarded to assess the early cracking tendency of concrete and the inclusion of 4 wt% lightburnt MgO with activity of 109 s ranked the best in crack resistance.

  4. In Vitro Cytotoxic Evaluation of MgO Nanoparticles and Their Effect on the Expression of ROS Genes

    Directory of Open Access Journals (Sweden)

    Rangarajulu Senthil Kumaran

    2015-04-01

    Full Text Available Water-dispersible MgO nanoparticles were tested to investigate their cytotoxic effects on oxidative stress gene expression. In this in vitro study, genes related to reactive oxygen species (ROS, glutathione S-transferase (GST and catalase, were quantified using real-time polymerase chain reactions (molecular level and molecular beacon technologies (cellular level. The monodispersed MgO nanoparticles, 20 nm in size, were used to treat human cancer cell lines (liver cancer epithelial cells at different concentrations (25, 75 and 150 µg/mL and incubation times (24, 48 and 72 h. Both the genetic and cellular cytotoxic screening methods produced consistent results, showing that GST and catalase ROS gene expression was maximized at 150 µg/mL nanoparticle treatment with 48 h incubation. However, the genotoxic effect of MgO nanoparticles was not significant compared with control experiments, which indicates its significant potential applications in nanomedicine as a diagnostic and therapeutic tool.

  5. Influence of hydrogen-doped MgO thin films on the discharge characteristics in plasma display panels

    International Nuclear Information System (INIS)

    In order to improve the discharge characteristics of Magnesium Oxide (MgO) thin films, hydrogen was doped to MgO thin films using an ion plating technique. Changes in the surface morphology, crystal orientation, optical properties, secondary electron emission coefficient, and defect states were studied with increasing hydrogen flow rates during the growth using field emission scanning electron microscope, X-ray diffraction, ellipsometry, γ-focused ion beam, and photoluminescence analysis. The change in firing voltage and delay time in plasma display panels (PDP) with the hydrogen-doped MgO thin films were also investigated. The results indicated that optimal hydrogen doping conditions can affect the surface structure and defect states: resulting in a significant reduction in the firing voltage and delay time of the PDP.

  6. Influence of MgO addition on the synthesis and electrical properties of sintered zinc-titanate ceramics

    International Nuclear Information System (INIS)

    Starting mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5 wt.% MgO) powders were mechanically activated for 15 min in a planetary ball mill. The powders obtained were sintered non-isothermally to temperatures between 800 and 1100 deg. C and then held at those temperatures for 120 min. Analysis of the influence of MgO addition on the synthesis of zinc-titanate ceramics showed that its addition increased slightly the temperature at which the reaction process started, accelerated the reaction and resulted in higher sample densities. These results were correlated with the results of structural characterization using X-ray powder diffraction method and SEM analysis. Also, the results of electric resistivity, capacitance and loss tangent of the sintered samples were obtained

  7. Effect of stabilizer on optical and structural properties of MgO thin films prepared by sol–gel method

    Indian Academy of Sciences (India)

    Z Bazhan; F E Ghodsi; J Mazloom

    2013-10-01

    The effects of monoethanolamine (MEA) and acetylacetone (ACAC) addition as stabilizer on the crystallization behaviour, morphology and optical properties of magnesium oxide were investigated using thermogravimetry (TG/DTG), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. Stabilizer addition reduces transparency of the films. MgO films prepared at 500 °C showed weak orientation of (200). However, the films prepared by addition of stabilizer are amorphous. MgO powders were prepared for exhibiting the structural properties. The patterns of MgO powders showed a preferred orientation of (200). The addition of stabilizer causes a reduction in grain size. SEM micrographs show that a homogenous and crack-free film can be prepared at 500 °C and addition of stabilizer causes an increase in packing density.

  8. Nickel catalysts supported on MgO with different specific surface area for carbon dioxide reforming of methane

    Institute of Scientific and Technical Information of China (English)

    Luming; Zhang; Lin; Li; Yuhua; Zhang; Yanxi; Zhao; Jinlin; Li

    2014-01-01

    In this paper, three kinds of MgO with different specific surface area were prepared, and their effects on the catalytic performance of nickel catalysts for the carbon dioxide reforming of methane were investigated. The results showed that MgO support with the higher specific surface area led to the higher dispersion of the active metal, which resulted in the higher initial activity. On the other hand, the specific surface area of MgO materials might not be the dominant factor for the basicity of support to chemisorb and activate CO2, which was another important factor for the performance of catalysts. Herein, Ni/MgO(CA) catalyst with proper specific surface area and strong ability to activate CO2exhibited stable catalytic property and the carbon species deposited on the Ni/MgO(CA) catalyst after 10 h of reaction at 650 ?C were mainly activated carbon species.

  9. Atomically-Smooth MgO films grown on Epitaxial Graphene by Pulsed Laser Deposition

    Science.gov (United States)

    Stuart, Sean; Sandin, Andreas; Rowe, Jack; Dougherty, Dan; Ulrich, Marc

    2013-03-01

    The growth of high quality insulating films on graphene is a crucial materials science task for graphene electronic and spintronic applications. It has been demonstrated that direct spin injection from a magnetic electrode to graphene is possible using MgO tunnel barriers of sufficient quality. We have used pulsed laser deposition (PLD) to grow thin magnesium oxide films directly on epitaxial graphene on SiC(0001). We observe very smooth film morphologies (typical rms roughness of ~ 0.4 nm) that are nearly independent of film thickness and conform to the substrate surface which had ~ 0.2 nm rms roughness. Surface roughness of 0.04 nm have been recorded for ~ 1nm films with no pinholes seen by AFM. XPS and XRD data show non crystalline, hydroxylated MgO films with uniform coverage. This work shows that PLD is a good technique to produce graphene-oxide interfaces without pre-deposition of an adhesion layer or graphene functionalization. The details and kinetics of the deposition process will be described with comparisons being made to other dielectric-on-graphene deposition approaches. Funded by ARO Staff Research Contract # W911NF.

  10. Annealing Effects on the Surface Plasmon of MgO Implanted with Gold

    Science.gov (United States)

    Ueda, A.; Mu, R.; Tung, Y. -S.; Henderson, D. O.; White, C. W.; Zuhr, R. A.; Zhu, Jane G.; Wang, P. W.

    1997-01-01

    Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

  11. Multi-cycling nanoindentation in MgO single crystals before and after ion irradiation

    International Nuclear Information System (INIS)

    The paper presents a nanoindentation study of MgO single crystals before and after ion irradiation up to a fluence of 1020 Ar+ m-2. It is confirmed that crystalline MgO is a brittle material of comparatively high nanohardness, ranging from H = 12.5 to 14.5 GPa depending on surface orientation. The plastic deformation is based on a dislocation glide with formation of slip bands giving rise to piling up around the indent which is strongly related to the sample crystallography. Repeated loading-unloading cycles (multi-cycling) revealed the appearance of hysteresis loops that are related to nanofracturing. Irradiation with 100 keV Ar+ ions resulted in a reproducible hardness increase to a value of H = 19 GPa independent of surface orientation. The indentation modulus E = 285 GPa remained unaffected by ion irradiation. Furthermore, no hysteresis loop in the force-displacement curve was formed with multi-cycling after implantation. This is explained in terms of point defect assisted plasticity: defect pinning will decrease the dislocation mobility and hence increase the hardness and also cause the sample to become less brittle resulting in a large decrease in nanocrack formations. In contrast to the dislocation glide, the point defect contribution to plastic deformation is almost orientation independent. This picture is supported by the orientation independent hardness as well as by the observation that ion irradiated samples exhibit a reduction in, and more homogeneously distributed, piling up around the indent

  12. Structure of Cr film epitaxially grown on MgO(0 0 1)

    International Nuclear Information System (INIS)

    Cr(0 0 1) films of thickness ∼100 nm were epitaxially grown on MgO(0 0 1) using molecular beam epitaxy at both room temperature and 550 oC. The structure of the films was characterized using high-resolution transmission electron microscopy, electron diffraction and electron energy-loss spectroscopy. Room temperature growth leads to highly oriented columnar structured grains in the film, while growth at 550 oC yields high-quality single-crystal Cr film, possessing a 45o rotational epitaxial relationship between the film and the substrate. For the single-crystal film, the interface exhibited coherent regions separated by equally spaced misfit dislocations. When imaged from the MgO[1 0 0]//Cr[1 1 0] direction, the dislocation spacing is 5.38 and 4.64 nm for the films grown at room temperature and 550 oC, respectively, which is slightly smaller than the expected value of 6.25 nm calculated from the differences in lattice spacing based on known lattice constants. The results presented here indicate that the lattice mismatch between the film and the substrate is accommodated mainly by interface misfit dislocations above some critical thickness. The electronic structure of the interface between the film and the substrate is also explored using electron energy-loss spectroscopy.

  13. Tunneling Anisotropic Magnetoresistance in Fe Nanoparticles Embedded in MgO Matrix

    Science.gov (United States)

    Pham, T. V.; Miwa, S.; Suzuki, Y.

    2016-05-01

    The tunnel magnetoresistance (TMR) effect is related to the relative orientation of the magnetizations of the two ferromagnetic electrodes in magnetic tunnel junctions (MTJs). The tunnel anisotropic magnetoresistance (TAMR) effect is related to the orientation of the magnetization with respect to the current direction or the crystallographic axes. Beyond the TMR, the TAMR is not only present in MTJs in which both electrodes are ferromagnetic but may also appear in tunnel structures with a single magnetic electrode. We investigated the magnetotransport properties in an Au/MgO/Fe nanoparticles/MgO/Cu tunnel junction. We found that both the TMR and TAMR can appear in tunnel junctions with Fe nanoparticles embedded in an MgO matrix. The TMR is attributed to spin-dependent tunneling between Fe nanoparticles, so the device resistance depends on the magnetization directions of adjacent Fe nanoparticles. The TAMR is attributed to the interfacial spin-orbit interaction, so the device resistance depends on each magnetization direction of an Fe nanoparticle. This is the first observation of the TAMR in Fe nanoparticles embedded in an MgO matrix.

  14. Polarity-manipulation based on nanoscale structural transformation on strained 2D MgO

    International Nuclear Information System (INIS)

    Strain induced nanoscale structural transformation is demonstrated in this paper to have the ability of triggering polarity flipping in a wide bandgap system of MgxZn1−xO/MgO/Al2O3. Relaxation dynamics of semiconductor components under large compressive pressures up to 13.7 GPa were studied by a combination of theoretical analysis and experimental characterizations including in situ reflection high-energy electron diffraction and high-resolution transmission electron microscopy. The gigantic force between MgZnO and ultrathin-MgO/Al2O3 delayed the structural transformation of MgZnO from six-fold cubic to four-fold wurtzite into the second monolayer, and consequently flipped the polarity of the film deposited on relaxed MgO. Additionally, dislocation-induced strain relaxation was suggested to happen around 1 nm thick cubic MgO grown on Al2O3, instead of the previous well-accepted concept that wurtzite structures can be inherited from the oxygen sub-lattice of sapphire substrates below the critical thickness. Finally, the structural transformation method employing an ultrathin-MgO interfacial layer was demonstrated to be a suitable technique for accommodating the large lattice mismatch comparing with the dislocation-relaxation mechanism achieving a UV photodetector with four orders of rejection ratio of the UV-to-visible photoresponse. (paper)

  15. Formation of Catalyst Model Dispersed of Pd on a thin MgO(100)

    Science.gov (United States)

    Baara, F.; Chemam, A.

    2016-04-01

    The nucleation kinetics or the formation of a catalyst model dispersed for the system Pd/thin MgO (100) are calculated by developing many programs using Fortran software. This simulation is based upon parameters studied in situ by transmission electron microscopy (TEM), related to the first quantitative study on the nucleation and the growth. Palladium nanoparticles deposited on thin MgO are tested in the temperature range 573-1073 K and deposition time of 1000 s. The nucleation kinetics are interpreted according to the theory of random nucleation. The general scheme is consisting of three stages namely, nucleation, growth and coalescence. The saturation density of clusters decreases when the substrate temperature increases following Arrhenius law. This behavior is in agreement with a recent AFM study for Ag/MgO and Au/MgO. The phenomenon of coalescence is explained via island migration process. It is shown that the coalescence occurs more rapidly when the substrate temperature is high.

  16. A Systematic Review of the Mysterious Caterpillar Fungus Ophiocordyceps sinensis in Dong-ChongXiaCao (冬蟲夏草 Dōng Chóng Xià Cǎo) and Related Bioactive Ingredients

    OpenAIRE

    Lo, Hui-Chen; Hsieh, Chienyan; Lin, Fang-Yi; Hsu, Tai-Hao

    2013-01-01

    The caterpillar fungus Ophiocordyceps sinensis (syn.† Cordyceps sinensis), which was originally used in traditional Tibetan and Chinese medicine, is called either “yartsa gunbu” or “DongChongXiaCao (冬蟲夏草 Dōng Chóng Xià Cǎo)” (“winter worm-summer grass”), respectively. The extremely high price of DongChongXiaCao, approximately USD $20,000 to 40,000 per kg, has led to it being regarded as “soft gold” in China. The multi-fungi hypothesis has been proposed for DongChongXiaCao; however, Hirsutella...

  17. MgO thin films deposited by electrostatic spray pyrolysis for protecting layers in AC-plasma display panel

    CERN Document Server

    Kim, S G

    1999-01-01

    MgO thin films were deposited on SiO sub 2 (100) substrates by using electrostatic spray pyrolysis and Mg(tmhd) sub 2 as the precursor. The growth rates of the films varyed from 34 to 87 A/min and were measured for various substrate and guide temperatures. X-ray diffraction analysis provide evidence that the MgO films deposited at temperatures as low as 400 approx 500 .deg. C had preferred orientation to (100) plane perpendicular to the substrate surface. X-ray photoelectron spectroscopy and Auger electron spectroscopy data indicated that there were few organics incorporated in the films.

  18. Transient Characterization of Carbon Monoxide, Carbon Dioxide and Oxygen Adsorbed on MgO and MgCO_3*

    OpenAIRE

    Yasuyuki, KONISHI; Toshio, KATAGIRI; Shichi, YASUI; Yoshinori, NAKANISHI; Tohru, KANNO; Masayoshi, KOBAYASHI

    1986-01-01

    The dynamic adsorption behavior of O_2, CO and CO_2 on MgO and MgCO_3 has been studied in detail at temperatures ranging from 150 to 171℃, by using the transient response method. 0n MgCO_3 no CO adsorbs and no CO oxidation proceeds. CO_2 is reversibly adsorbed obeying the Langmuir isotherm and the heat of adsorption is evaluated to be 2.7kcal/mol. On MgO, on the other hand, no CO adsorbs whereas the oxidation of CO easily proceeds and the rate equation is expressed : γ=kPco^Po_2^ The apparent...

  19. Does H2O improve the catalytic activity of Au1-4/MgO towards CO oxidation?

    OpenAIRE

    Amft, Martin; Skorodumova, Natalia V.

    2011-01-01

    The present density functional theory study addresses the question whether the presence of H2O influences the catalytic activity of small gold clusters, Au1-4/MgO(100), towards the oxidation of carbon monoxide. To this end, we studied the (co-)adsorption of H2O and CO/O2 on these gold clusters. The ground state structures in the presence of all three molecular species, that we found, are Au1O2/MgO and Au2-4CO/MgO with H2O adsorbed on the surface in the proximity of the clusters-molecule compl...

  20. EXAFS AND XANES STUDIES ON THE LOCAL STRUCTURES OF METAL IONS IN METAL DOPED MgO SYSTEMS

    OpenAIRE

    Asakura, K.; Iwasawa, Y.; Kuroda, H.

    1986-01-01

    The local structures around the metals in metal-doped MgO catalysts were studied by EXAFS and XANES spectroscopies in connection with their catalysis which markedly depends on the kinds of doped metal ions. In the M-MgO samples (M=Ni2+, Cu2+, and Co2+), the M ions occupied the octahedral sites of MgO lattice by replacement with Mg2+. On the other hand, in the system of M-MgO samples (M = Fe3+ and Cr3+ ) the M ions existed as the cluster structure with a Koch-Cohen type M4-framework. The pair ...

  1. Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum

    CERN Document Server

    Song, Zhenjun

    2016-01-01

    The dehydrogenation reaction of methanol on metal supported MgO(100) films has been studied by employing periodic density functional calculations. As far as we know, the dehydrogenation of single methanol molecule over inert oxide insulators such as MgO has never been realized before without the introduction of defects and low coordinated atoms. By depositing the very thin oxide films on Mo substrate we have successfully obtained the dissociative state of methanol. The dehydrogenation reaction is energetically exothermic and nearly barrierless. The metal supported thin oxide films studied here provide a versatile approach to enhance the activity and properties of oxides.

  2. Ethanol-to-Butadiene Conversion over SiO2-MgO Catalysts: Synthesis-Structure-Performance Relationships

    OpenAIRE

    Angelici, C.

    2015-01-01

    The work presented in this PhD Thesis provides new insights into the underlying reasons that make SiO2-MgO materials excellent catalysts for the ethanol-to-butadiene Lebedev process. In particular, the preparation technique of choice affects the structural properties of the resulting SiO2-MgO materials considerably and therefore the distribution, i.e. nature and amount, of acidic-basic sites. Given the complex cascade of elementary steps required, striking a precise balance in the latter is k...

  3. The CAO Short-Run Macroeconometric Model of Japanese Economy (2004 version) -Basic Structure, Multipliers, and Economic Policy Analyses- (in Japanese)

    OpenAIRE

    Keiko Murata; Tatsuo Saito

    2005-01-01

    This paper describes the basic structure and multipliers of the revised version of the CAO Short-Run Macroeconometric Model of the Japanese Economy, which was firstly released in 1998 (Hori et al. [1998]).The model is basically a demand-oriented, traditional Keynesian-type model with IS-LM-BP framework; however, it adopts recent developments in econometrics, such as co-integration, and error-correction to ensure a long-run equilibrium.

  4. Electrophysiological effects of Ca antagonists, tetrodotoxin, [Ca]o and [Na]o on myocardium of hibernating chipmunks: possible involvement of Na-Ca exchange mechanism.

    OpenAIRE

    Kondo, N

    1987-01-01

    The electrophysiological performance of myocardium of hibernating chipmunks was investigated in the presence of Ca antagonists and tetrodotoxin, and the effects of high [Ca]o and low [Na]o were examined. The action potential of the preparations was characterized by the low amplitude of the plateau phase (APp). Ca antagonists, nifedipine (10(-6) M) and nitrendipine (2 X 10(-6) M), did not significantly inhibit this APp or the contraction. These nifedipine-insensitive electromechanical response...

  5. Evaluation of Heterogeneous Options: Effects of MgO versus UO2 Matrix Selection for Minor Actinide Targets in a Sodium Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    M. Pope; S. Bays; R. Ferrer

    2008-03-01

    The primary focus of this work was to compare MgO with UO2 as target matrix material options for burning minor actinides in a transmutation target within a sodium fast reactor. This analysis compared the transmutation performance of target assemblies having UO2 matrix to those having specifically MgO inert matrix.

  6. Study on initial current leakage spots in CoFeB-capped MgO tunnel barrier by conductive atomic force microscopy

    Science.gov (United States)

    Sato, Soshi; Honjo, Hiroaki; Ikeda, Shoji; Ohno, Hideo; Endoh, Tetsuo; Niwa, Masaaki

    2016-04-01

    Although a microscopic study on a MgO tunnel barrier by atomic force microscopy has been required to study the reliability of magnetic tunnel junctions, the deterioration of bare MgO due to the adsorption of H2O and CO2 has been a problem. For an accurate evaluation of the initial current leakage spots distributed in a MgO tunnel barrier, a CoFeB-capped MgO tunnel barrier structure is proposed for evaluation by means of conductive atomic force microscopy. The CoFeB capping layer thickness was optimized to be 2.0 nm to prevent H2O and CO2 adsorption on the MgO and to minimize the series resistance due to the capping layer. The initial current leakage spot density of the MgO tunnel barrier with the optimized CoFeB capping layer exponentially increased as the thickness of the MgO tunnel barrier decreased from 1.6 to 0.8 nm, and was 157 spots/µm2 at the MgO thickness of 1.2 nm and the bias voltage of 0.5 V.

  7. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system

    International Nuclear Information System (INIS)

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. The electrical resistance of CaO coatings produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li that contained 0.5-85 wt% dissolved Ca was measured as a function of time at temperatures between 250 and 600 C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420 C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was ∼106 Ω at 400 C. Thermal cycling between 300 and 700 C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at ≥360 C. (orig.)

  8. A density functional theory study of the adsorption of Hg and HgCl2 on a CaO(001) surface

    Institute of Scientific and Technical Information of China (English)

    GUO Xin; ZHENG Chuguang; LU Nanxia

    2007-01-01

    The adsorption of mercury and mercury chloride on a CaO(001) surface was investigated by the density functional theory (DFT) by using Ca9O9 cluster embedded in an electrostatic field represented by 178 point charges at the crystal CaO lattice positions.For the mercury molecular axis normal to the surface,the mercury can only coordinate to the O2- anion and has a very weak binding energy of 19.649 kJ/mol.When the mercury chloride molecular axis is vertical to the surface,the Cl atom coordinates to the Ca2+ cation and has a binding energy of 23.699 kJ/mol.When the mercury chloride molecular axis is parallel to the surface,the Hg atom coordinates to the O2- anion and has a binding energy of 87.829 kJ/mol,which means that the parallel geometry is more stable than the vertical one.The present calculations show that CaO injection could substantially reduce gaseous mercury chloride,but have no apparent effect on the mercury,which is compatible with the available experimental results.This research will provide valuable information for optimizing and selecting a sorbent for the trace element in flue gas.

  9. Effect of CaO doping on corrosion resistance of Cu/(NiFe2O4-10NiO) cermet inert anode for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The CaO-doped Cu/(NiFe2O4-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process,and their corrosion resistance to Na3AlF6-K3AlF6-AI2O3 melt was studied.The results show that the relative density of 5Cu/(NiFe2O4-10NiO) cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added.During the electrolysis,the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO atceramic grain boundary,which accelerates the penetration of electrolyte.Thus,the corrosion resistance to melts ofCu/(NiFe2O4-10NiO) cermet inert anode is reduced.To improve the corrosion resistance of the cermet inert anode,the content of CaO doped should be decreased and the technology of cleaning the ceramic grain boundary should be applied.

  10. CaO insulator coatings and self-healing of defects on V-Cr-Ti alloys in liquid lithium system

    International Nuclear Information System (INIS)

    Electrically insulating and corrosion-resistant coatings are required at the liquid metal/structural interface in fusion first-wall/blanket applications. Electrical resistance of CaO coatings that were produced on V-5%Cr-5%Ti by exposure of the alloy to liquid Li containing 0.5-85 wt.% dissolved Ca was measured as a function of time at temperatures between 250 and 600 degrees C. The solute element, Ca in liquid Li, reacted with the alloy substrate at 400-420 degrees C to produce a CaO coating. Resistance of the coating layer measured in-situ in liquid Li was ∼106 Ω at 400 degrees C. Thermal cycling between 300 and 700 degrees C changed the coating layer resistance, which followed insulator behavior. These results suggest that thin homogeneous coatings can be produced on variously shaped surfaces by controlling the exposure time, temperature, and composition of the liquid metal. The technique can be applied to various shapes (e.g., inside/outside of tubes, complex geometrical shapes) because the coating is formed by liquid-phase reaction. Examination of the specimens after cooling to room temperature revealed no spallation, but homogeneous crazing cracks were present in the CaO coating. Additional tests to investigate the in-situ self-healing behavior of the cracks indicated that rapid healing occurred at ≥360 degrees C

  11. Use of CaO as an activator for producing a price-competitive non-cement structural binder using ground granulated blast furnace slag

    International Nuclear Information System (INIS)

    The use of calcium oxide (CaO) demonstrates a superior potential for the activation of ground granulated blast furnace slag (GGBFS), and it produces a higher mechanical strength than calcium hydroxide [Ca(OH)2]. The mechanical strength differences between CaO- and Ca(OH)2-activated GGBFS binders are explored using isothermal calorimetry, powder X-ray diffraction, thermogravimetric and differential thermal analysis (TGA and DTA) as well as compressive strength testing. Calcium silicate hydrate (C–S–H), Ca(OH)2 and a hydrotalcite-like phase are found as reaction products in all samples. The TGA and DTA results indicate that the use of CaO produces more C–S–H, although this is not likely to be the primary cause of higher strength development in the CaO-activated GGBFS. Rather, other factors such as porosity may govern the strength at a higher order of magnitude. Significant reduction of Ca(OH)2 occurs only with the use of Ca(OH)2, followed by the formation of carbonate (CaCO3), indicating carbonation. -- Highlights: •CaO showed a better potential for the activation of GGBFS than Ca(OH)2. •Strength test, XRD, TGA/DTA and isothermal calorimetry are used. •C-S-H, Ca(OH)2, and a hydrotalcite-like phase are found in all samples. •The use of Ca(OH)2 causes some degree of carbonation

  12. Epitaxial growth of MgO and Fe/MgO/Fe magnetic tunnel junctions on (100)-Si by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Epitaxial growth of MgO barrier on Si is of technological importance due to the symmetry filtering effect of the MgO barrier in conjunction with bcc-ferromagnets. We study the epitaxial growth of MgO on (100)-Si by molecular beam epitaxy. MgO matches Si with 4:3 cell ratio, which renders Fe to be 45 deg. rotated relative to Si, in sharp contrast to the direct epitaxial growth of Fe on Si. The compressive strains from Si lead to the formation of small angle grain boundaries in MgO below 5 nm, and also affect the transport characteristics of Fe/MgO/Fe magnetic tunnel junctions formed on top

  13. Effects of MgO addition on phase evolution and flux pinning of Bi-2212/Ag tapes fabricated by electrophoretic deposition and partial-melting processing

    International Nuclear Information System (INIS)

    MgO or SrSO4 particulates were introduced into Bi-2212/Ag tapes during the fabrication process with the intention of producing flux pinning centres. It was found that (i) MgO or SrSO4 normal particles added to Bi-2212 superconductor do not react chemically with or corrupt the Bi-2212 phase, but MgO may alter the phase evolution during the partial melting and the solidification of Bi-2212 and reduce the second-phase inclusions, (ii) MgO addition may enhance the flux pinning potential in a certain region of temperature and magnetic field (the contributions of MgO addition to the flux pinning potential are still not clear) and (iii) SrSO4 addition appears to have no effect on the properties of finished samples. (author)

  14. The mass balance calculation of hydrothermal alteration in Sarcheshmeh porphyry copper deposit

    Directory of Open Access Journals (Sweden)

    Mohammad Maanijou

    2013-10-01

    Full Text Available Sarcheshmeh porphyry copper deposit is located 65 km southwest of Rafsanjan in Kerman province. The Sarcheshmeh deposit belongs to the southeastern part of Urumieh-Dokhtar magmatic assemblage (i.e., Dehaj-Sarduyeh zone. Intrusion of Sarcheshmeh granodiorite stock in faulted and thrusted early-Tertiary volcano-sedimentary deposits, led to mineralization in Miocene. In this research, the mass changes and element mobilities during hydrothermal process of potassic alteration were studied relative to fresh rock from the deeper parts of the plutonic body, phyllic relative to potassic, argillic relative to phyllic and propylitic alteration relative to fresh andesites surrounding the deposit. In the potassic zone, enrichment in Fe2O3 and K2O is so clear, because of increasing Fe coming from biotite alteration and presence of K-feldspar, respectively. Copper and molybdenum enrichments resulted from presence of chalcopyrite, bornite and molybdenite mineralization in this zone. Enrichment of SiO2 and depletion of CaO, MgO, Na2O and K2O in the phyllic zone resulted from leaching of sodium, calcium and magnesium from the aluminosilicate rocks and alteration of K-feldspar to sericite and quartz. In the argillic zone, Al2O3, CaO, MgO, Na2O and MnO have also been enriched in which increasing Al2O3 may be from kaolinite and illite formation. Also, enrichment in SiO2, Al2O3 and CaO in propylitic alteration zone can be attributed to the formation of chlorite, epidote and calcite as indicative minerals of this zone.

  15. Mapping the geographic distribution of canopy species communities in lowland Amazon rainforest with CAO-AToMS (Invited)

    Science.gov (United States)

    Feret, J.; Asner, G. P.

    2013-12-01

    Mapping regional canopy diversity will greatly advance our understanding as well as the conservation of tropical rainforests. Changes in species composition across space and time are particularly important to understand the influence of climate, human activity and environmental factors on these ecosystems, but to date such monitoring is extremely challenging and is facing a scale gap between small-scale, highly detailed field studies and large-scale, low-resolution satellite observations. Advances were recently made in the field of spectroscopic imagery for the estimation of canopy alpha-diversity, and an original approach based on the segmentation of the spectral space proved its ability to estimate Shannon diversity index with unprecedented accuracy. We adapted this method in order to estimate spectral dissimilarity across landscape as a proxy for changes in species composition. We applied this approach and mapped species composition over four sites located in lowland rainforest of Peruvian Amazon. This study was based on spectroscopic imagery acquired using the Carnegie Airborne Observatory (CAO) Airborne Taxonomic Mapping System (AToMS), operating a unique sensor combining the fine spectral and spatial resolution required for such task. We obtained accurate estimation of Bray-Curtis distance between pairs of plots, which is the most commonly used metric to estimate dissimilarity in species composition (n=497 pairs, r=0.63). The maps of species composition were then compared to topo-hydrographic properties. Our results indicated a strong shift in species composition and community diversity between floodplain and terra firme terrain conditions as well as a significantly higher diversity of species communities within Amazonian floodplains. These results pave the way for global mapping of tropical canopy diversity at fine geographic resolution.

  16. Caos determinístico em um modelo simplificado de cadeia produtiva Deterministic chaos in simplified supply chain model

    Directory of Open Access Journals (Sweden)

    Júlio César Bastos de Figueiredo

    2013-06-01

    Full Text Available Este trabalho tem por objetivo apresentar um modelo teórico simplificado de cadeia produtiva onde as relações entre o número de competidores, os tempos de resposta para ajustes da produção e a intensidade da resposta das empresas levam intrinsecamente ao surgimento de oscilações caóticas na oferta e na demanda. No modelo proposto, desenvolvido com o uso da metodologia de dinâmica de sistemas, as flutuações irregulares na demanda e nos preços estão intimamente relacionadas com a própria estrutura da cadeia, ou seja, com suas regras, políticas e capacidades produtivas. São feitas considerações sobre a importância do estudo de caos aplicado à economia e são discutidas técnicas para caracterização de comportamento caótico em séries econômicas.The purpose of this study was to present a simplified supply chain model where the relations between the number of competitors, the delay in production adjustments, and the intensity response of each company lead, intrinsically, to the emergence of chaotic oscillations in supply and demand. In the considered model, developed with the use of the System Dynamics methodology, the irregular fluctuations in demand and prices are closely related to the supply chain structure, that is, its rules, policies and capabilities. Discussions about the importance of the study of chaos applied to the economy are developed and specific techniques for characterization of chaotic behavior in economic time series are presented.

  17. Assembly of FePt L10 nanoparticles grown on MgO(110) with self-organized groove structure

    International Nuclear Information System (INIS)

    We have fabricated an FePt nanoparticle assembly on a MgO(110) with a self-organized structure. Prior to FePt deposition, the MgO(110) substrate was annealed at 1273 K in air to develop self-organized grooves running along the [110] direction with average periodicity of 14.5 nm. Subsequently a very thin FePt layer with nominal thickness of 1.5 nm was sputtered onto the MgO substrate at 973 K, resulting in FePt L10 nanoparticles with 2-4 nm in diameter aligned along the grooves. Each FePt nanoparticle was a L10 single crystal with its c-axis tilting 45 deg. or -45 deg. from the substrate normal that corresponds to MgO[100] or [010]. The magnetic properties of the FePt nanoparticle assembly well reflected such c-axis distribution, and their switching behavior almost followed the Stoner-Wohlfarth model

  18. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    Science.gov (United States)

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  19. Methylglyoxal (MGO) inhibits proliferation and induces cell death of human glioblastoma multiforme T98G and U87MG cells.

    Science.gov (United States)

    Paul-Samojedny, Monika; Łasut, Barbara; Pudełko, Adam; Fila-Daniłow, Anna; Kowalczyk, Małgorzata; Suchanek-Raif, Renata; Zieliński, Michał; Borkowska, Paulina; Kowalski, Jan

    2016-05-01

    Glioblastoma multiforme (GBM) is the most malignant and invasive human brain tumor and it is characterized by a poor prognosis and short survival time. Current treatment strategies for GBM using surgery, chemotherapy and/or radiotherapy are ineffective. Thus new therapeutic strategies to target GBM are urgently needed. The effect of methylglyoxal (MGO) on the cell cycle, cell death and proliferation of human GBM cells was investigated. The T98G and U87MG cell lines were cultured in modified EMEM supplemented with 10% fetal bovine serum and maintained at 37°C in a humidified atmosphere of 5% CO2 in air. Cells were exposed to methylglyoxal (0.025mM) per 72h. The influence of MGO on T98G and U87MG cell cycle, proliferation and apoptosis was evaluated as well. Cell cycle phase distribution, proliferation, apoptosis were analyzed by flow cytometry. MGO causes changes in cell cycle and induces accumulation of G1/G0-phase cells and reduced fraction of cells in S and G2/M phases. We have also observed inhibition of cell proliferation and induction of apoptosis in cancer cells. We have also revealed that MGO induces senescence of U87MG but not T98G cells, but further studies are necessary in order to clarify and check mechanism of action of methylglyoxal and it Is a positive phenomenon for the treatment of GBM. PMID:27133062

  20. Tailoring the porosity and shrinkage of extruded MgO support tubes for oxygen separation membranes by thermoplastic feedstock development

    DEFF Research Database (Denmark)

    Kothanda Ramachandran, Dhavanesan; Kaiser, Andreas; Glasscock, Julie;

    optimized with respect to flow behavior, co-sintering and final layer properties. Crucial parameters, such as similar flow resistance and linear shrinkage for both materials are necessary to achieve asymmetric structure successfully. Porosity above 30% and final grain size for the MgO support is...

  1. Influence of MgO and Hybrid Fiber on the Bonding Strength between Reactive Powder Concrete and Old Concrete

    Directory of Open Access Journals (Sweden)

    Mo Jinchuan

    2016-01-01

    Full Text Available The reactive powder concrete (RPC was used as concrete repair material in this paper. The influence of steel fiber, steel fiber + MgO, and steel fiber + MgO + polypropylene fiber (PPF on the mechanical properties of RPC repair materials and the splitting tensile strength between RPC and old concrete was studied. Influences of steel fiber, MgO, and PPF on the splitting tensile strength were further examined by using scanning electronic microscopy (SEM and drying shrinkage test. Results indicated that the compressive and flexural strength was improved with the increasing of steel fiber volume fraction. However, the bonding strength showed a trend from rise to decline with the increasing of steel fiber volume fraction. Although MgO caused mechanical performance degradation of RPC, it improved bonding strength between RPC and existing concrete. The influence of PPF on the mechanical properties of RPC was not obvious, whereas it further improved bonding strength by significantly reducing the early age shrinkage of RPC. Finally, the relationship of drying shrinkage and splitting tensile strength was studied, and the equation between the splitting tensile strength relative index and logarithm of drying shrinkage was obtained by function fitting.

  2. Self-healing of drying shrinkage cracks in cement-based materials incorporating reactive MgO

    Science.gov (United States)

    Qureshi, T. S.; Al-Tabbaa, A.

    2016-08-01

    Excessive drying shrinkage is one of the major issues of concern for longevity and reduced strength performance of concrete structures. It can cause the formation of cracks in the concrete. This research aims to improve the autogenous self-healing capacity of traditional Portland cement (PC) systems, adding expansive minerals such as reactive magnesium oxide (MgO) in terms of drying shrinkage crack healing. Two different reactive grades (high ‘N50’and moderately high ‘92–200’) of MgO were added with PC. Cracks were induced in the samples with restraining end prisms through natural drying shrinkage over 28 days after casting. Samples were then cured under water for 28 and 56 days, and self-healing capacity was investigated in terms of mechanical strength recovery, crack sealing efficiency and improvement in durability. Finally, microstructures of the healing materials were investigated using FT-IR, XRD, and SEM-EDX. Overall N50 mixes show higher expansion and drying shrinkage compared to 92–200 mixes. Autogenous self-healing performance of the MgO containing samples were much higher compared to control (only PC) mixes. Cracks up to 500 μm were sealed in most MgO containing samples after 28 days. In the microstructural investigations, highly expansive Mg-rich hydro-carbonate bridges were found along with traditional calcium-based, self-healing compounds (calcite, portlandite, calcium silicate hydrates and ettringite).

  3. Elasticity of MgO to 11 GPa with an independent absolute pressure scale: Implications for pressure calibration

    Energy Technology Data Exchange (ETDEWEB)

    Li, B.; Woody, K; Kung, J

    2006-01-01

    P and S wave velocities and unit cell parameters (density) of MgO are measured simultaneously up to 11 GPa using combined ultrasonic interferometry and in situ X-ray diffraction techniques. The elastic bulk and shear moduli as well as their pressure derivatives are obtained by fitting the measured velocity and density data to the third-order finite strain equations, yielding K0S = 163.5(11) GPa, K'0S = 4.20(10), G0 = 129.8(6) GPa, and G'0 = 2.42(6), independent of pressure. These properties are subsequently used in a Birch-Murnaghan equation of state to determine the sample pressures at the observed strains. Comparison of the 300K isothermal compression of MgO indicates that current pressure scales from recent studies are in better than 1.5% agreement. We find that pressures derived from secondary pressure standards (NaCl, ruby fluorescence) at 300K are lower than those from current MgO scales by 5-8% ({approx}6% on average) in the entire pressure range of the current experiment. If this is taken into account, discrepancy in previous static compression studies on MgO at 300K can be reconciled, and a better agreement with the present study can be achieved.

  4. Charge modulation of magnetization in X-doped MgO nanotube clusters (X=C, N)

    Science.gov (United States)

    Wang, Su-Fang; Chen, Li-Yong; Zhang, Tao; Xie, You

    2016-02-01

    First-principles calculations based on density functional theory are performed to study the magnetic and electronic properties of X-doped 8×7 MgO nanotube clusters (X=C, N). The N dopant easily occupies the O-site at the edge of MgO nanotube, embracing neutral or charged defect state, and induces notable magnetization in N-doped MgO tubular cluster. More important, this p-electron magnetization can be significantly modulated as the charged state of the defect changes. Regarding C doping, impurity atom readily substitute the Mg atom located at the edge of MgO nanotube to form neutral defect, and net magnetization is found to be zero. The calculated electron densities of states show that the O-site N doping at the edge greatly narrows or even destroys band-gap, while it enlarges somewhat for the Mg-site C doping at the edge. The results are likely to stimulate a promising class of materials for various applications ranging from spintronics to magneto-optics.

  5. Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

    Science.gov (United States)

    Fuente, Silvia A.; Ferullo, Ricardo M.; Domancich, Nicolás F.; Castellani, Norberto J.

    2011-01-01

    The adsorption of nitric oxide (NO) on Au n (n = 1-3) particles deposited on anionic (O 2-) sites of MgO has been studied using the DFT (Density Functional Theory) approach. The regular O 2- sites of MgO(100) and the sites in edge and corner topological defects with high symmetry of MgO were considered. The adhesion energy of Au n to MgO is larger for Au 2 and Au 3 due to higher polarization effects. On the other hand, the interaction strength of NO with supported Au n particles depends mainly on the electronic configuration (open or closed shell) of the particle; the Au particles with odd number of atoms show larger NO binding energies. A comparison was performed with the reactivity of free Au n particles. From this, it is possible to conclude that the support enhances the NO-Au n bonding strength for the monomer, weakens this interaction in the case of the dimer, and does not have an effect in the trimers. Besides, the NO-Au n bonding is essentially insensitive to the coordination of the anionic site where the Au n particle is linked. A large red-shift of the N-O stretching frequency was obtained, particularly for the Au particles with odd number of atoms, due to a negative charge transfer from Au to NO.

  6. Adsorption of NO on Au atoms and dimers supported on MgO(1 0 0): DFT studies

    Science.gov (United States)

    Fuente, Silvia A.; Belelli, Patricia G.; Ferullo, Ricardo M.; Castellani, Norberto J.

    2008-05-01

    The adsorption of NO on single gold atoms and Au 2 dimers deposited on regular O 2- sites and neutral oxygen vacancies (F s sites) of the MgO(1 0 0) surface have been studied by means of DFT calculations. For Au 1/MgO the adsorption of NO is stronger when the Au atom is supported on an anionic site than when it is on a F s site, with adsorption binding energies of 1.1 and 0.5 eV, respectively. In the first case the spin density is mainly concentrated on the metal atom and protruding from the surface. In such a way, an active site against radicals such as NO is generated. On the F s site, the presence of the vacancy delocalizes the spin into the substrate, weakening its coupling with NO. For Au 2/MgO, as this system has a closed-shell configuration, the NO molecules bonds weakly with Au 2. Regarding the N-O stretching frequencies, a very strong shift of ˜340-400 cm -1 to lower frequencies is observed for Au 1/MgO in comparison with free NO.

  7. Size-dependent structure of CdSe nanoclusters formed after ion implantation in MgO

    NARCIS (Netherlands)

    van Huis, MA; van Veen, A; Schut, H; Eijt, SWH; Kooi, BJ; De Hosson, JTM

    2005-01-01

    The band gap as well as the optical and structural properties of semiconductor CdSe nanoclusters change as a function of the nanocluster size. Embedded CdSe nanoclusters in MgO were created by means of sequential Cd and Se ion implantation followed by thermal annealing. Changes during annealing were

  8. Electric field effect on a double MgO CoFeB-based free layer

    Science.gov (United States)

    Huang, Jiancheng; Sim, Cheow Hin; Naik, Vinayak Bharat; Tran, Michael; Lim, Sze Ter; Huang, Aihong; Yap, Qi Jia; Han, Guchang

    2016-03-01

    We study the electric field (EF) effect on MgO/CoFeB/Ta/CoFeB/MgO free layers by varying the thickness of the top MgO layer. The two CoFeB/MgO interfaces oppose the change in magnetic anisotropy from each other and this can be understood by considering the voltage drop as well as the efficiency of the anisotropy modulation from both interfaces. These results are proven by monitoring both coercivity and anisotropy field as a function of the applied EF. From the fit to the model, we show that the bottom CoFeB/MgO interface has a higher EF efficiency than the top interface.

  9. Continuous electropolishing of Hastelloy substrates for ion-beam assisted deposition of MgO

    Energy Technology Data Exchange (ETDEWEB)

    Kreiskott, Sascha; Arendt, Paul N; Bronisz, Lawrence E; Foltyn, Steve R; Matias, Vladimir [Superconductivity Technology Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2003-05-01

    We demonstrate the applicability of continuous electropolishing for the preparation of metal tapes for ion-beam assisted deposition of MgO for the fabrication of in-plane textured template layers. These templates are used for the fabrication of second generation high temperature superconducting wires utilizing YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} coatings on metallic substrates. Surface roughness values below 1 nm and local slopes of less than 1 deg. could be achieved with the electropolishing process. Mean surface roughness values are lower with the use of electropolishing and slopes of surface roughness inclines are significantly reduced compared to the best results of mechanical polishing (3.5 nm and 5 deg., respectively). The cost-effective process of electropolishing shows great promise for the fabrication of second generation high temperature superconducting wire.

  10. Continuous electropolishing of Hastelloy substrates for ion-beam assisted deposition of MgO

    International Nuclear Information System (INIS)

    We demonstrate the applicability of continuous electropolishing for the preparation of metal tapes for ion-beam assisted deposition of MgO for the fabrication of in-plane textured template layers. These templates are used for the fabrication of second generation high temperature superconducting wires utilizing YBa2Cu3O7-δ coatings on metallic substrates. Surface roughness values below 1 nm and local slopes of less than 1 deg. could be achieved with the electropolishing process. Mean surface roughness values are lower with the use of electropolishing and slopes of surface roughness inclines are significantly reduced compared to the best results of mechanical polishing (3.5 nm and 5 deg., respectively). The cost-effective process of electropolishing shows great promise for the fabrication of second generation high temperature superconducting wire

  11. Electronic and Chemical Properties of a Surface-Terminated Screw Dislocation in MgO

    Energy Technology Data Exchange (ETDEWEB)

    Mckenna, Keith P.

    2013-12-18

    Dislocations represent an important and ubiquitous class of topological defect found at the surfaces of metal oxide materials. They are thought to influence processes as diverse as crystal growth, corrosion, charge trapping, luminescence, molecular adsorption and catalytic activity, however, their electronic and chemical properties remain poorly understood. Here, through a detailed first principles investigation into the properties of a surface terminated screw dislocation in MgO we provide atomistic insight into these issues. We show that surface dislocations can exhibit intriguing electron trapping properties which are important for understanding the chemical and electronic characteristics of oxide surfaces. The results presented in this article taken together with recent experimental reports show that surface dislocations can be equally as important as more commonly considered surface defects, such as steps, kinks and vacanies, but are now just beginning to be understood.

  12. Optical, scintillation and dosimeter properties of MgO translucent ceramic doped with Cr3+

    Science.gov (United States)

    Kato, Takumi; Okada, Go; Yanagida, Takayuki

    2016-04-01

    We have investigated the photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimeter properties of MgO translucent ceramic doped with Cr3+ ion (0.001, 0.01 and 0.1%). The ceramic samples were synthesized by a Spark Plasma Sintering (SPS) technique. The broad and sharp emission peaks appeared around 600-850 nm in all the samples. The PL decay time constants of all the samples were a few ms which were on the typical order of Cr3+ doped phosphors. As with the PL, the peak resulted from Cr3+ ion was detected in the scintillation spectra. The TSL glow curves showed the main peak around 140 °C. The TSL response was confirmed to be linear to the irradiation dose over the dose range from 0.1 to 1000 mGy.

  13. On the low-lying states of MgO. II

    Science.gov (United States)

    Bauschlicher, C. W., Jr.; Lengsfield, B. H., III; Silver, D. M.; Yarkony, D. R.

    1981-01-01

    Using a double zeta plus polarization basis set of Slater orbitals, full valence MCSCF (FVMCSCF) calculations were performed for the low-lying states of MgO. For each state the FVMCSCF calculations were used to identify the important configurations which are then used in the MCSCF calculation and subsequently as references in a single and double excitation CI calculation. This approach is found to treat all states equivalently, with the maximum error in the computed transition energies and equilibrium bond lengths of 800/cm and approximately 0.03 A, respectively. The b 3 Sigma + state which has yet to be characterized experimentally is predicted to have a transition energy of approximately 8300/cm and a bond length of 1.79 A. A spectroscopic analysis of the potential curves indicates that their shapes are in quite reasonable agreement with the range of experimental results.

  14. High performance NbN nanowire superconducting single photon detectors fabricated on MgO substrates

    CERN Document Server

    Marsili, F; Fiore, A; Gaggero, A; Mattioli, F; Leoni, R; Benkahoul, M; Lévy, F

    2007-01-01

    We demonstrate high-performance nanowire superconducting single photon detectors (SSPDs) on ultrathin NbN films grown at a temperature compatible with monolithic integration. NbN films ranging from 150nm to 3nm in thickness were deposited by dc magnetron sputtering on MgO substrates at 400C. The superconducting properties of NbN films were optimized studying the effects of deposition parameters on film properties. SSPDs were fabricated on high quality NbN films of different thickness (7 to 3nm) deposited under optimal conditions. Electrical and optical characterizations were performed on the SSPDs. The highest QE value measured at 4.2K is 20% at 1300nm.

  15. Shock Response and Phase Transitions of MgO at Planetary Impact Conditions

    Science.gov (United States)

    Root, Seth; Shulenburger, Luke; Lemke, Raymond W.; Dolan, Daniel H.; Mattsson, Thomas R.; Desjarlais, Michael P.

    2015-11-01

    The moon-forming impact and the subsequent evolution of the proto-Earth is strongly dependent on the properties of materials at the extreme conditions generated by this violent collision. We examine the high pressure behavior of MgO, one of the dominant constituents in Earth's mantle, using high-precision, plate impact shock compression experiments performed on Sandia National Laboratories' Z Machine and extensive quantum calculations using density functional theory (DFT) and quantum Monte Carlo (QMC) methods. The combined data span from ambient conditions to 1.2 TPa and 42 000 K, showing solid-solid and solid-liquid phase boundaries. Furthermore our results indicate that under impact the solid and liquid phases coexist for more than 100 GPa, pushing complete melting to pressures in excess of 600 GPa. The high pressure required for complete shock melting has implications for a broad range of planetary collision events.

  16. Adsorption of 2-propanol on MgO surface: A combined experimental and theoretical study

    Science.gov (United States)

    Fuente, Silvia A.; Ferretti, Cristián A.; Domancich, Nicolás F.; Díez, Verónica K.; Apesteguía, Carlos R.; Di Cosimo, J. Isabel; Ferullo, Ricardo M.; Castellani, Norberto J.

    2015-02-01

    The adsorption of 2-propanol (or isopropanol) on MgO was studied using infrared (IR) spectroscopy and density functional theory (DFT) simulations. The analysis of IR spectra indicates that the molecule can adsorb either molecularly or dissociatively. DFT calculations show that the adsorption mode depends on the active site of the catalyst. While on perfect terrace it adsorbs non-dissociatively, on edge and on threefold coordinated O anion (O-corner sites) the adsorption occurs dissociatively by breaking the Osbnd H bond without activation barrier giving 2-propoxide and a surface hydroxyl group. Calculations also suggest that vacant oxygen centers on terrace, edge and corner are also possible sites for non-dissociative adsorption. On Mg ions located at corners the adsorption is strong but non-dissociative, while on a Mg vacancy at the same position the molecule easily dissociates. Frequency modes are also calculated and compared in detail with experimental IR spectra.

  17. The compression study of MgO up to 3Mbar

    Science.gov (United States)

    Sakai, T.; Nishitani, N.; Ohtani, E.; Hirao, N.

    2011-12-01

    Periclase (MgO) is a most fundamental oxide in the terrestrial planets. It is also widely used as a pressure standard material for the high pressure experiment. Moreover, recently Super Earths which has a few times of Earth's mass were found in the extrasolar system. Theoretical study implied that MgSiO3 decompose to MgO and SiO2 in such huge planet's interior (Umemoto et al. 2006). Thus, the compression behavior of MgO at multi-megabar pressure is important to understand the Super Earth's interior. Here we report the compression study of MgO up to 3Mbar. Periclase powder (Wako Pure Chemical Industries, Ltd.) and platinum black (Wako Pure Chemical Industries, Ltd.) were used as the starting material. We used a symmetric-type diamond anvil cell for high pressure generation. The experimental pressure was determined by the Vinet equation of state of platinum as reported by Matsui et al. (2009). The sample was annealed by a double-sided laser-heating method using a fiber laser at the BL10XU beamline, Japanese SPring-8 synchrotron facility, in order to minimize the deviatoric stress in the sample. Experimental pressures were measured after laser annealing. A monochromatic incident X-ray beam with a wavelength of 0.41297(7) Å and 0.41298(8) Å at BL10XU was collimated to a diameter less than 10 μm (Ohishi et al., 2008). X-ray diffraction spectra were collected on an imaging plate (IP) with an exposure time of 5 min. The two-dimensional X-ray diffraction image was integrated as a function of 2θ to give a conventional one-dimensional X-ray diffraction pattern. The diffraction of cerium oxide (CeO2) was used to determine the wavelength and the distance between the sample and the IP. Periclase was successfully compressed up to 308 GPa. We estimated the uniaxial stress of platinum at 308 GPa. The uniaxial stress t is described as t = -3M1/(M0αS) (Singh and Takemura, 2001). Here, M0 and M1 are the intercept and slope of the gamma plot, respectively. The coefficient α is

  18. Two-color laser desorption of nanostructured MgO thin films

    International Nuclear Information System (INIS)

    Neutral magnesium atom emission from nanostructured MgO thin films is induced using two-color nanosecond laser excitation. We find that combined vis/UV excitation, for single-color pulse energies below the desorption threshold, induces neutral Mg-atom emission with hyperthermal kinetic energies in the range of 0.1-0.2 eV. The observed metal atom emission is consistent with a mechanism involving rapid electron transfer to three-coordinated Mg surface sites. The two-color Mg-atom signal is significant only for parallel laser polarizations and temporally overlapped laser pulses indicating that intermediate excited states are short-lived compared to the 5 ns laser pulse duration.

  19. Caos, fluidos y flujos

    Directory of Open Access Journals (Sweden)

    Luis Fernando Herrera Díaz

    2011-02-01

    Full Text Available During the last 30 years, the world of science has been revolutionized with the birth of a new paradigm: this form of seeing the world is known as The Chaos Theory. "In their short life it has already touched all the branches of knowledge, including Engineering" says Mora (1998.1t is so that many of the will known engineers like Aris in the ñeld of the chemical reactors, Froment in heterogeneous catalysis, Coppens who investigates the phenomena's of diffusionreaction in Zeolites, Julio Ottino in the mixing offluids, have begun to improve old outlines through thís theory. The present article seeks for to show the main concepts, in which the theory of chaos is based, through simple examples, showing mainly its relationships with chemical engineering, such as flow and mixing offluids.

  20. Smelting reduction of MgO in molten slag by liquid ferrosilicon

    Directory of Open Access Journals (Sweden)

    Tang, Qifeng

    2016-06-01

    Full Text Available The smelting reduction of magnesium oxide was researched in this paper. The effect of molten slag composition and reduction temperature on percent reduction of magnesium oxide were discussed, and kinetics of smelting reduction of magnesium oxide in molten slag was studied. The results showed that the reduction extent of magnesium oxide increased by increasing either one of the following factors: the initial mass ratio of Al2O3/SiO2, the addition of CaF2, the initial molar ratio of Si/2MgO, and reaction temperature. The overall smelting reduction was controlled by mass transfer in slag with an apparent activation energy 586 kJ mol-1.En este trabajo se estudia la reducción de óxido de magnesio. La influencia de la composición de las escorias y de la temperatura de reducción sobre el porcentaje de reducción de óxido de magnesio han sido discutidas, y asimismo se ha estudiado la cinética de la reducción del óxido de magnesio en escorias fundidas. Los resultados muestran que la reducción se incrementa al aumentar alguno de los siguientes factores: la proporción de Al2O3/SiO2, la adición de CaF2, la proporción molar de Si/2MgO y la temperatura de reacción. En general la reducción fue controlada por la transferencia de masa en la escoria con una energía aparente de 586 kJ mol-1.

  1. Adsorption and dissociation of hydrogen on MgO surface: A first-principles study

    International Nuclear Information System (INIS)

    Periodic density functional theory (DFT) has been used to investigate the adsorption and dissociation of hydrogen on MgO surface. Weak molecular adsorptions were observed and the bridge site with the vertical mode was the most favorable molecular adsorption site. The reaction barrier along with dissociation of the hydrogen molecule on the MgO(0 0 1) surface has also been studied. Our results show the most favorable dissociation channel needs activation energy of around 2.2 eV at the bridge site which is in agreement with the previous results (2.34-2.94 eV). The minimum energy pathway for surface diffusion of atomic H indicates the existence of small classical barriers with a value of about 0.37 eV. And our calculations show that H atom can diffuse from the surface sites to subsurface and further into the bulk sites. The most stable absorption configurations are the interstitial octahedral sites in diffusion movements. The largest barrier in these processes is up to 1.52 eV in the diffusion step of surface to subsurface. Once atomic H penetrates the subsurface layers, the corresponding diffusion barriers decrease to 1.02 eV (from subsurface-1 (SB1) to subsurface-2 (SB2) site) and 1.2 eV (from SB2 to subsurface-3 (SB3) site), respectively. Our calculations indicate that dissociation of molecular hydrogen is strongly inhibited on the magnesium oxide surface during the hydrogenation on magnesium films.

  2. Sonocatalyzed decolorization of synthetic textile wastewater using sonochemically synthesized MgO nanostructures.

    Science.gov (United States)

    Darvishi Cheshmeh Soltani, Reza; Safari, Mahdi; Mashayekhi, Masumeh

    2016-05-01

    The present study focused on the synthesis of nanostructured MgO via sonochemical method and its application as sonocatalyst for the decolorization of Basic Red 46 (BR46) dye under ultrasonic irradiation. The sonocatalyst was characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray microanalysis (EDX). In the following, the sonocatalytic removal of the dye under different operational conditions was evaluated kinetically on the basis of pseudo first-order kinetic model. The reaction rate of sonocatalyzed decolorization using MgO nanostructures (12.7 × 10(-3) min(-1)) was more efficient than that of ultrasound alone (2.0 × 10(-3) min(-1)). The increased sonocatalyst dosage showed better sonocatalytic activity but the application of excessive dosage should be avoided. The presence of periodate ions substantially increased the decolorization rate from 14.76 × 10(-3) to 33.4 × 10(-3) min(-1). Although the application of aeration favored the decolorization rate (17.8 × 10(-3) min(-1)), the addition of hydrogen peroxide resulted in a considerable decrease in the decolorization rate (9.5 × 10(-3) min(-1)) due to its scavenging effects at specific concentrations. Unlike alcoholic compounds, the addition of phenol had an insignificant scavenging effect on the sonocatalysis. A mineralization rate of 7.4 × 10(-3) min(-1) was obtained within 120 min. The intermediate byproducts were also detected using GC-MS analysis. PMID:26615797

  3. Ex Situ and Operando Studies on the Role of Copper in Cu-Promoted SiO2-MgO Catalysts for the Lebedev Ethanol-to-Butadiene Process

    NARCIS (Netherlands)

    Angelici, Carlo; Meirer, Florian; van der Eerden, Ad M. J.; Schaink, Herrick L.; Goryachev, Andrey; Hofmann, Jan P.; Hensen, Emiel J. M.; Weckhuysen, Bert M.; Bruijnincx, Pieter C. A.

    2015-01-01

    Dehydrogenation promoters greatly enhance the performance of SiO2-MgO catalysts in the Lebedev process. Here, the effect of preparation method and order of addition of Cu on the structure and performance of Cu-promoted SiO2-MgO materials is detailed. Addition of Cu to MgO via incipient wetness impre

  4. Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    Science.gov (United States)

    Belmeguenai, M.; Tuzcuoglu, H.; Gabor, M. S.; Petrisor, T.; Tiusan, C.; Zighem, F.; Chérif, S. M.; Moch, P.

    2014-01-01

    10 nm and 50 nm Co2FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (Ta), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing Ta, while the uniaxial anisotropy field is nearly unaffected by Ta within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with Ta. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10-3 and 1.3×10-3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively).

  5. Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    International Nuclear Information System (INIS)

    10 nm and 50 nm Co2FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (Ta), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing Ta, while the uniaxial anisotropy field is nearly unaffected by Ta within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with Ta. Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10−3 and 1.3×10−3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

  6. Ferromagnetism in IV main group element (C and transition metal (Mn doped MgO: A density functional perspective

    Directory of Open Access Journals (Sweden)

    Vinit Sharma

    2011-09-01

    Full Text Available The formation of magnetic moment due to the dopants with p-orbital (d-orbital is named d0 (d − magnetism, where the ion without (with partially filled d states is found to be responsible for the observed magnetic properties. To study the origin of magnetism at a fundamental electronic level in such materials, as a representative case, we theoretically investigate ferromagnetism in MgO doped with transition metal (Mn and non-metal (C. The generalized gradient approximation based first-principles calculations are used to investigate substitutional doping of metal (Mn and non-metal (C, both with and without the presence of neighboring oxygen vacancy sites. Furthermore, the case of co-doping of (Mn, C in MgO system is also investigated. It is observed that the oxygen vacancies do not play a role in tuning the ferromagnetism in presence of Mn dopants, but have a significant influence on total magnetism of the C doped system. In fact, we find that in MgO the d0 magnetism through C doping is curtailed by pairing of the substitutional dopant with naturally occurring O vacancies. On the other hand, in case of (Mn, C co-doped MgO the strong hybridization between the C (2p and the Mn(3d states suggests that co-doping is a promising approach to enhance the ferromagnetic coupling between the nearest-neighboring dopant and host atoms. Therefore, (Mn,C co-doped MgO is expected to be a ferromagnetic semiconductor with long ranged ferromagnetism and high Curie temperature.

  7. Evaluation of Grain Growth of Corn and Sorghum under K2O Application and Irrigation According

    Directory of Open Access Journals (Sweden)

    Sayed Alireza Valadabadi

    2009-08-01

    Full Text Available In this experiment, interactive effects of different potassium application and water restrict on graingrowth in Iran. The experimental unit had designed by achieved treatment in factorial on the basis completelyrandomized block design with three replicates. Certain factors including potassium and non-potassiumapplications (0 and 200 kg/ha, certain field crops (corn and sorghum and w ater supply were studied. In thisstudy crops water supply was determined by indicated irrigation conditions by keeping leaf Relative WaterContent (RW C > 95% (non-drought stress condition or irrigation conditions and drought condition by RWC= 60-70%. We noticed, however K fertilizer significantly increased the grain growth rate of plants and althoughthe non-drought stress treatment significantly increased grain growth rate. Whereas K application persist lessdamaging of drought stress result and it enabled plant to significantly grow its grain under the droughtconditions. Our finding may give applicable advice to commercial farmers and agricultural researches formanagement and concern on fertilizer strategy and carefully estim ate soil potassium supply w ithin dry or semidryareas as most challengeable issues of environmental safety.

  8. Evaluation of Grain Growth of Corn and Sorghum under K2O Application and Irrigation According

    OpenAIRE

    Sayed Alireza Valadabadi

    2009-01-01

    In this experiment, interactive effects of different potassium application and water restrict on graingrowth in Iran. The experimental unit had designed by achieved treatment in factorial on the basis completelyrandomized block design with three replicates. Certain factors including potassium and non-potassiumapplications (0 and 200 kg/ha), certain field crops (corn and sorghum) and w ater supply were studied. In thisstudy crops water supply was determined by indicated irrigation conditions b...

  9. Polyethylene Nanocomposites for the Next Generation of Ultralow-Transmission-Loss HVDC Cables: Insulation Containing Moisture-Resistant MgO Nanoparticles.

    Science.gov (United States)

    Pourrahimi, Amir Masoud; Pallon, Love K H; Liu, Dongming; Hoang, Tuan Anh; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

    2016-06-15

    The use of MgO nanoparticles in polyethylene for cable insulation has attracted considerable interest, although in humid media the surface regions of the nanoparticles undergo a conversion to a hydroxide phase. A facile method to obtain MgO nanoparticles with a large surface area and remarkable inertness to humidity is presented. The method involves (a) low temperature (400 °C) thermal decomposition of Mg(OH)2, (b) a silicone oxide coating to conceal the nanoparticles and prevent interparticle sintering upon exposure to high temperatures, and (c) heat treatment at 1000 °C. The formation of the hydroxide phase on these silicone oxide-coated MgO nanoparticles after extended exposure to humid air was assessed by thermogravimetry, infrared spectroscopy, and X-ray diffraction. The nanoparticles showed essentially no sign of any hydroxide phase compared to particles prepared by the conventional single-step thermal decomposition of Mg(OH)2. The moisture-resistant MgO nanoparticles showed improved dispersion and interfacial adhesion in the LDPE matrix with smaller nanosized particle clusters compared with conventionally prepared MgO. The addition of 1 wt % moisture-resistant MgO nanoparticles was sufficient to decrease the conductivity of polyethylene 30 times. The reduction in conductivity is discussed in terms of defect concentration on the surface of the moisture-resistant MgO nanoparticles at the polymer/nanoparticle interface. PMID:27203860

  10. Evidence for boron diffusion into sub-stoichiometric MgO (001) barriers in CoFeB/MgO-based magnetic tunnel junctions

    Science.gov (United States)

    Harnchana, V.; Hindmarch, A. T.; Sarahan, M. C.; Marrows, C. H.; Brown, A. P.; Brydson, R. M. D.

    2013-04-01

    Evidence of boron diffusion into the MgO barrier of a CoFeB/MgO based magnetic tunnel junction has been identified using analytical scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy. Structures were deposited by DC/RF-magnetron sputtering, where defective, sub-stoichiometric MgO barriers degrading device performance have been previously mitigated against by deposition of thin Mg layers prior to MgO deposition. We show that despite the protection offered by the Mg layer, disorder in the MgO barrier is still evident by STEM analysis and is a consequence of the oxidation of the Co40Fe40B20 surface during MgO deposition. Evidence of boron diffusion from CoFeB into the MgO barrier in the as-deposited and annealed structure is also presented, which in the as-deposited case we suggest results from the defective structures at the barrier interfaces. Annealing at 375 °C results in the presence of B in the trigonal coordination of [BO3]3- in the MgO barrier and partial crystallization of the top electrode (we presume there is also some boron diffusion into the Ta capping layer). The bottom electrode, however, fails to crystallize and much of the boron is retained in this thicker electrode. A higher annealing temperature or lower initial boron content is required to crystallize the bottom electrode.

  11. Atomistic processes of Ni and Pd atoms on MgO(001) surfaces with surface-functional hydroxyl groups: ab-initio calculations

    International Nuclear Information System (INIS)

    By using ab-initio calculations based on the density functional theory, we systematically studied the adsorption and the diffusion properties of Ni and Pd (XM) atoms on hydroxylated MgO(001) [MgOhdr(001)] surfaces. The energetics of adsorption, binding, and diffusion are presented and compared with those of XM atoms on clean MgO(001). The calculated energetics showed considerably enhanced adsorption of XM on MgOhdr(001) compared to that on MgO(001). The stronger binding of XM and OH on MgO(001) indicated the favorable formation of XMOH complexes instead of XM dimers on the surface. In the case of surface diffusion, XMOH on MgO(001) was observed to diffuse via a hopping process over the surface hollow sites. The diffusion of XMOH on MgO(001) was slightly faster than that of XM atoms. Compared to the surface diffusion of PtOH on MgO(001), the surface diffusion energy barriers were in the following order, PtOH (0.89 eV) > NiOH (0.71 eV) > PdOH (0.43 eV). Therefore, the surface dynamics of Ni, Pd, and Pt on MgOhdr(001) driven thermally at temperatures relevant to the catalytic activities of metal clusters are expected to be different. The electronic structures and the charge states of XMOH on MgO(001) were analyzed further and compared with those of XM on MgO(001).

  12. Nano SiO2 and MgO Improve the Properties of Porous β-TCP Scaffolds via Advanced Manufacturing Technology

    OpenAIRE

    Chengde Gao; Pingpin Wei; Pei Feng; Tao Xiao; Cijun Shuai; Shuping Peng

    2015-01-01

    Nano SiO2 and MgO particles were incorporated into β-tricalcium phosphate (β-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical β-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped β-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the ph...

  13. Evidence for boron diffusion into sub-stoichiometric MgO (001) barriers in CoFeB/MgO-based magnetic tunnel junctions.

    OpenAIRE

    Harnchana, V.; Hindmarch, A. T.; Sarahan, M.C.; Marrows, C. H.; Brown, A.P.; Brydson, R. M. D.

    2013-01-01

    Evidence of boron diffusion into the MgO barrier of a CoFeB/MgO based magnetic tunnel junction has been identified using analytical scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy. Structures were deposited by DC/RF-magnetron sputtering, where defective, sub-stoichiometric MgO barriers degrading device performance have been previously mitigated against by deposition of thin Mg layers prior to MgO deposition. We show that despite the protection offered by ...

  14. Penggunaan Arang Cangkang Kelapa Sawit dan MgO untuk Bahan Baku Pembuatan Keramik Berpori yang Digunakan sebagai Filter Gas Buang Kenderaan Berbahan Bakar Bensin

    OpenAIRE

    Hasibuan, Erwinsyah

    2015-01-01

    The fabrication of cordierite ceramic has been done by using the basic material of MgO and palm shell ash. The mixture of the raw material of ceramic (MgO, clay) is in mass percentage. The ingredients are arranged in the packages of the MgO and palm shell using the ratio of 0 : 70, 5 : 65, 10 : 60, 15 : 55, 20 : 50. Then 30% sample mass of clay is added to each sample. Each of the sample mixture is stirred in an adequate water by mixer. After the stirring is homogeneous, it is poured into the...

  15. Effects of Al2O3 and/or CaO on properties of yttria stabilized zirconia electrolyte doped with multi-elements

    International Nuclear Information System (INIS)

    Yttria stabilized zirconia (YSZ) has a high oxide ion conductivity at high temperatures. Some rare earth elements (e.g., Yb, Sc, Dy) with similar cation radii to Zr4+ can dissolve into ZrO2, increasing its vacancy concentration and crystal lattice distortion, and therefore enhancing its conductivity and lowering the activation energy. It is expected this material could be used as intermediate temperature electrolyte. In the present work, YSZ electrolyte materials doped by multi-elements (Sc2O3 or Dy2O3 and Yb2O3) were prepared by high temperature solid-state method. The high temperature conductivity was improved obviously, reaching 0.18 S/cm at 1000 deg. C, but the density and mechanical properties of sintered materials were not sufficiently high. It is found that sinterability and mechanical properties could be improved by inclusion of a small amount of Al2O3 and/or CaO into the multi-elements doped YSZ materials and our results proved it. The results showed density and bending strength of sintered bodies were enhanced by Al2O3 addition by 4.6% and 30%, respectively, while the conductivity did not degrade remarkably. But the degradation in bending strength and conductivity resulting from the CaO addition happened due to the second phase formed at the grain boundary. XRD patterns showed that all samples had cubic fluorite structure and crystalline lattice parameter was increased. SEM photographs obviously revealed the grain growth for the samples with CaO inclusion

  16. THE INFLUENCE OF CaO AND P2O5 OF BONE ASH UPON THE REACTIVITY AND THE BURNABILITY OF CEMENT RAW MIXTURES

    Directory of Open Access Journals (Sweden)

    TOMÁŠ IFKA

    2012-03-01

    Full Text Available The influence of CaO and P2O5 upon the reactivity of cement raw meal was investigated in this paper. Ash of bone meal containing Ca3(PO42 - 3CaO·P2O5 was used as the source of P2O5. Two series of samples with different content of the ash of bone meal were prepared. In the first series, the ash of bone was added into cement raw meal. The second series of samples were prepared by considering ash as one of CaO sources. Therefore, the total content of CaO in cement raw meal was kept constant, while the amount of P2O5 increased. These different series of samples were investigated by analyzing free lime content in the clinkers. The XRD analysis and Electron Micro Probe Analyzer analysis of the clinkers were also carried out. Two parameters were used to characterize the reactivity of cement raw meal: content of free lime and Burnability Index (BI calculated from free lime content in both series of samples burnt at 1350 ºC, 1400 ºC, 1450 ºC and 1500 ºC. According to the first parameter, P2O5 content that drastically makes worse the reactivity of cement raw meal was found at 1.11 wt.% in the first series, while this limit has reached 1.52 wt.% in the second one. According to the BI, the limit of P2O5 was found at 1.42 wt. % in the first series and 1, 61 wt.% in the second one. Furthermore, EPMA has demonstrated the presence of P2O5 in both calcium silicate phases forming thus solid solutions.

  17. Simultaneous retrieval of aerosols and ocean properties: A classic inverse modeling approach. I. Analytic Jacobians from the linearized CAO-DISORT model

    International Nuclear Information System (INIS)

    In this paper and the sequel, we investigate the application of classic inverse methods based on iterative least-squares cost-function minimization to the simultaneous retrieval of aerosol and ocean properties from visible and near infrared spectral radiance measurements such as those from the SeaWiFS and MODIS instruments. Radiance measurements at the satellite are simulated directly using an accurate coupled atmosphere-ocean-discrete-ordinate radiative transfer (CAO-DISORT) code as the main component of the forward model. For this kind of cost-function inverse problem, we require the forward model to generate weighting functions (radiance partial derivatives) with respect to the aerosol and marine properties to be retrieved, and to other model parameters which are sources of error in the retrievals. In this paper, we report on the linearization of the CAO-DISORT model. This linearization provides a complete analytic differentiation of the coupled-media radiative transfer theory, and it allows the model to generate analytic weighting functions for any atmospheric or marine parameter. For high solar zenith angles, we give an implementation of the pseudo-spherical (P-S) approach to solar beam attenuation in the atmosphere in the linearized model. We summarize a number of performance enhancements such as the use of an exact single-scattering calculation to improve accuracy. We derive inherent optical property inputs for the linearized CAO-DISORT code for a simple 2-parameter bio-optical model for the marine environment coupled to a 2-parameter bimodal atmospheric aerosol medium

  18. Study of the charge kinetics of MgO (1 1 0) subjected to high energy electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Boughariou, A., E-mail: aicha_boughariou@yahoo.fr [LaMaCoP, Université de Sfax pour le sud, Faculté des Sciences, 3038 Sfax Tunisie (Tunisia); Kallel, A. [LaMaCoP, Université de Sfax pour le sud, Faculté des Sciences, 3038 Sfax Tunisie (Tunisia); Blaise, G. [LPS, Université Paris-Sud XI, Batiment 510, Orsay 91405 (France)

    2014-09-15

    Highlights: • Variation of the logarithm of SEE yield with the injected dose in MgO (1 1 0) at high energy. • Critical energy E{sub C} of MgO (1 1 0). • Formation of an electrostatic mirror. • Breakdown phenomenon (current density effect). - Abstract: This article presents a study performed with a dedicated scanning electron microscope (SEM) on the electrical property evolution of magnesium oxide (1 1 0) single crystal during 15 and 30 keV irradiation. First, the charging behavior is studied during the charge injection process at low current density J{sub 0}, by measuring the logarithm of the secondary electron emission yield (lnσ). Next, we have investigated the dependence on the current density of the charge-trapping phenomena in MgO (1 1 0). The results shown that beyond the crossover energy E{sub 2}, the observed effects varies depending on whether the energy of the primary electrons is lower or higher than an energy called critical energy E{sub c} = 20 keV (in the case of MgO (1 1 0)). When irradiating the material at E{sub 0} < E{sub c} and at low J{sub 0}, self regulated regime is obtained, if J{sub 0} is sufficiently intense an aging regime is reached. This latter regime is characterized by a positive surface charge, when a negative charge was expected. At E{sub 0} > E{sub c}, and for low J{sub 0}, the detailed monitoring of the charge kinetic of MgO (1 1 0) at high primary energy E{sub 0} = 30 keV, permit to show that the combined effect of the increased negative surface potential during irradiation and extractor field below the surface of MgO fact that lnσ undergoes a strong slope failure at the beginning of the injection and stabilizes at a value much less than zero leading to the formation of an electrostatic mirror. At high J{sub 0}, the consequences of the charge accumulation are violent and a breakdown phenomenon is observed.

  19. Study of the charge kinetics of MgO (1 1 0) subjected to high energy electron irradiation

    International Nuclear Information System (INIS)

    Highlights: • Variation of the logarithm of SEE yield with the injected dose in MgO (1 1 0) at high energy. • Critical energy EC of MgO (1 1 0). • Formation of an electrostatic mirror. • Breakdown phenomenon (current density effect). - Abstract: This article presents a study performed with a dedicated scanning electron microscope (SEM) on the electrical property evolution of magnesium oxide (1 1 0) single crystal during 15 and 30 keV irradiation. First, the charging behavior is studied during the charge injection process at low current density J0, by measuring the logarithm of the secondary electron emission yield (lnσ). Next, we have investigated the dependence on the current density of the charge-trapping phenomena in MgO (1 1 0). The results shown that beyond the crossover energy E2, the observed effects varies depending on whether the energy of the primary electrons is lower or higher than an energy called critical energy Ec = 20 keV (in the case of MgO (1 1 0)). When irradiating the material at E0 < Ec and at low J0, self regulated regime is obtained, if J0 is sufficiently intense an aging regime is reached. This latter regime is characterized by a positive surface charge, when a negative charge was expected. At E0 > Ec, and for low J0, the detailed monitoring of the charge kinetic of MgO (1 1 0) at high primary energy E0 = 30 keV, permit to show that the combined effect of the increased negative surface potential during irradiation and extractor field below the surface of MgO fact that lnσ undergoes a strong slope failure at the beginning of the injection and stabilizes at a value much less than zero leading to the formation of an electrostatic mirror. At high J0, the consequences of the charge accumulation are violent and a breakdown phenomenon is observed

  20. Análisis, construcción, simulación y sincronización de circuitos electrónicos prototipos de Caos

    OpenAIRE

    Bordel Sánchez, Borja

    2014-01-01

    El proyecto tiene como objetivo el estudio de siete Sistemas Dinámicos, yendo de los que son paradigma de Caos a los más complejos, y sus posibles aplicaciones en comunicaciones privadas, bioingeniería y comunicaciones ópticas. El conjunto de sistemas seleccionados incluye algunos ejemplos paradigmáticos de Dinámicas Caóticas, así como nuevas propuestas, tanto de do sistemas básicos como de un sistema que tiene soluciones más complejas, nunca antes estudiados. Se logrará, de esta manera, rea...