Electron microscopy characterization of mechanically alloyed and hot consolidates Cu-Cr<sub>3sub>C>2sub> particles

Directory of Open Access Journals (Sweden)

López, M.

2005-08-01

Full Text Available Mechanically alloyed copper-ceramic composites have been obtained with the purpose of studying their use as copper-based material for electrical equipment. For high-temperature applications, dispersion-strengthened copper alloys are attractive due to their excellent combination of thermal and electrical conductivity, mechanical strength retention and microstructural stability. In this work, powder mixtures of pure copper with 2 vol % Cr<sub>3sub>C>2sub>, milled during 4, 6, 10, 12 and 15 h in a high-energy planetary balls mill under argon atmosphere, were consolidated by hot isostatic pressing, applying a pressure of 100 MPa at 1073 K for two hours, to obtain materials with a fine microstructure. The Cu-Cr<sub>3sub>C>2sub> alloys were studied by scanning electron microscopy (SEM, electron microprobe (EPMA and transmission electron microscopy (TEM. Mechanical properties and electrical conductivity were also studied. The average tensile strength and electrical conductivity were found to be 500 MPa and 50 % IACS, respectively. The Cr<sub>3sub>C>2sub> ceramics show good stability during hot consolidation. Contributing to a further strengthening of the alloy during the hot consolidation, uniformly-distributed Fe-carbide particles of nanometric size precipitated in the copper matrix. Fe-Cr oxycarbides formed in the interphase between Cr<sub>3sub>C>2sub> particles and the copper matrix cause the low ductility of Cu-Cr<sub>3sub>C>2sub> alloys. Said particles are attributed to impurities/contamination generated from the milling process.

Se obtuvieron aleaciones compuestas de Cu-Cr<sub>3sub>C>2sub>, aleadas mecánicamente, para estudiar futuras aplicaciones en componentes eléctricos. A altas temperaturas, las aleaciones de base cobre reforzadas por dispersión, son atractivas por su excelente conductividad térmica y eléctrica, propiedades mecánicas y estabilidad microstructural. En este estudio

Effect of synthesis methods on the Ca{sub 3}Co{sub 4}O{sub 9} thermoelectric ceramic performances

Energy Technology Data Exchange (ETDEWEB)

Sotelo, A.; Rasekh, Sh.; Torres, M.A. [Instituto de Ciencia de Materiales de Aragón, CSIC—Universidad de Zaragoza, M" a de Luna, 3, 50018-Zaragoza (Spain); Bosque, P. [Centro Universitario de la Defensa de Zaragoza. Academia General Militar. Ctra. de Huesca s/n. 50090, Zaragoza (Spain); Madre, M.A., E-mail: amadre@unizar.es [Instituto de Ciencia de Materiales de Aragón, CSIC—Universidad de Zaragoza, M" a de Luna, 3, 50018-Zaragoza (Spain); Diez, J.C. [Instituto de Ciencia de Materiales de Aragón, CSIC—Universidad de Zaragoza, M" a de Luna, 3, 50018-Zaragoza (Spain)

2015-01-15

Three different synthesis methods producing nanometric grain sizes, coprecipitation with ammonium carbonate, oxalic acid, and by attrition milling have been studied to produce Ca{sub 3}Co{sub 4}O{sub 9} ceramics and compared with the classical solid state route. These three processes have produced high reactive precursors and all the organic material and CaCO{sub 3}·have been decomposed in a single thermal treatment. Coprecipitation leads to pure Ca{sub 3}Co{sub 4}O{sub 9} phase, while attrition milling and classical solid state produce small amounts of Ca{sub 3}Co{sub 2}O{sub 6} secondary phase. Power factor values are similar for all three samples, being slightly lower for the ones produced by attrition milling. These values are much higher than the obtained in samples prepared by the classical solid state method, used as reference. The maximum power factor values determined at 800 °C (∼0.43 mW/K{sup 2} m) are slightly higher than the best reported values obtained in textured ones which also show much higher density values. - Graphical abstract: Impressive raise of PF in Ca{sub 3}Co{sub 4}O{sub 9} thermoelectric materials obtained from nanometric grains. - Highlights: • Ca{sub 3}Co{sub 4}O{sub 9} has been produced by four different methods. • Precursors particle sizes influences on the final performances. • Coprecipitation methods produce single Ca{sub 3}Co{sub 4}O{sub 9} phase. • Power factor reaches values comparable to high density textured materials.

Study on the dielectric properties of Al2O3/TiO2 sub-nanometric laminates: effect of the bottom electrode and the total thickness

Science.gov (United States)

Ben Elbahri, M.; Kahouli, A.; Mercey, B.; Lebedev, O.; Donner, W.; Lüders, U.

2018-02-01

Dielectrics based on amorphous sub-nanometric laminates of TiO2 and Al2O3 are subject to elevated dielectric losses and leakage currents, in large parts due to the extremely thin individual layer thickness chosen for the creation of the Maxwell-Wagner relaxation and therefore the high apparent dielectric constants. The optimization of performances of the laminate itself being strongly limited by this contradiction concerning its internal structure, we will show in this study that modifications of the dielectric stack of capacitors based on these sub-nanometric laminates can positively influence the dielectric losses and the leakage, as for example the nature of the electrodes, the introduction of thick insulating layers at the laminate/electrode interfaces and the modification of the total laminate thickness. The optimization of the dielectric stack leads to the demonstration of a capacitor with an apparent dielectric constant of 90, combined with low dielectric loss (tan δ) of 7 · 10-2 and with leakage currents smaller than 1  ×  10-6 A cm-2 at 10 MV m-1.

Synthesis, characterization and comparison of Li{sub 1,05}M{sub 0,02}Mn{sub 1,98}O{sub 4} (M = Al{sup 3+} or + Ga{sup 3+}) obtained by calcination in muffle and microwave; Sintese, caracterizacao e comparacao dos Li{sub 1,05}Mn{sub 1,98}M{sub 0,02}O{sub 4} (M= Al{sup 3+} ou GA{sup 3+}) obtidos por calcinacao em mufla e microondas

Energy Technology Data Exchange (ETDEWEB)

Santana, L.K.; Canobre, S.C.; Amaral, F.A., E-mail: fabioamaral@yahoo.com.br [Universidade Federal de Uberlandia (UFU), MG (Brazil). Instituto de Quimica. Laboratorio de Armazenamento de Energia e Tratamento de Efluentes

2014-07-01

Due to the economic and environmental importance of using LiMn{sub 2}O{sub 4} as cathode batteries, the goal of this work was to synthesize LiMn{sub 2}O{sub 4} doped and undoped, comparing methods of calcination kiln and microwave. The precursors were obtained by Pechini method. The resulting samples were structurally characterized by XRD, morphology by SEM and area by B.E.T. XRD results were compared to card JCPDS 35-0782 regarding the pure LiMn{sub 2}O{sub 4}. The DRX results indicate that the calcination furnace was more efficient for obtaining doped oxides. However, the use of microwave was effective for rapid attainment of non-doped spinel close to those found for the pure spinel structural features. The surface area values confirm the existence of clusters and particles with nanometric features. Oxides synthesized in both procedures showed small, organized and highly crystalline particles, demonstrating the efficiency of the methodology and Pechini methods of calcination compared. (author)

Mechanical properties of nanometre volumes of material

International Nuclear Information System (INIS)

Pethica, J.B.; Coliver, W.

1989-01-01

A new, differential method for determining the stiffness of a sub-micronindentation contact area is presented. This allows measurement of elastic modulus as well as plastic hardness, continuously during a single indentation, and without the need for discrete unloading cycles. Some of the new experiments that become possible with this technique, especially at the nanometre scale, are described. The authors show quantitatively that electropolished tungsten reproducibly exhibits the ideal theoretical lattice strength at small indentation loads

Low-temperature preparation of La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} sinterable nanopowders by the polymeric organic complex solution method

Energy Technology Data Exchange (ETDEWEB)

Perez-Falcon, J.M.; Moure, A.; Tartaj, J. [Electroceramics Department, Instituto de Ceramica y Vidrio (CSIC), Kelsen 5, 28049 Madrid (Spain)

2011-02-15

In this work, powders of La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} were prepared by the auto-combustion of ethylene glycol-metal nitrate polymerised gel precursor. This method (polymeric organic complex solution) allows decreasing the processing temperature and simplifies the whole procedure. A single phase material is obtained at 300 C lower than that needed by conventional solid state reaction (SSR). The reduced particle size and low agglomeration increases the reactivity of powders and therefore, the sintering temperature is also reduced in 200 C with respect to the conventional SSR method. As a consequence of that, the microstructures are controlled maintaining the grain size in an almost nanometric range. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Influence of ZnO and TiO{sub 2} particle sizes in the mechanical and dielectric properties of vulcanized rubber

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, Neudys; Custal, Maria del Angels; Rodriguez, Daniel [Sicame Company, Barcelona (Spain); Riba, Jordi-Roger [Departament d' Enginyeria Eletrica, Universitat Politecnica de Catalunya, Terrasssa (Spain); Armelin, Elaine, E-mail: elaine.armelin@upc.edu [Universitat Politecnica de Catalunya, Barcelona (Spain)

2017-07-15

The novelty of the present study relies on the straightforward sonication of ZnO and TiO{sub 2} and incorporation to a complex formulation of latex, with other several organic-inorganic additives that influences the cross-linking reactions. The new elastomer with particles carefully sonicated exhibit improved electrical and mechanical properties. Strong interaction among the nanoparticles and the polymer amorphous phase has been proved by means of FTIR, SEM and XRD analyses. The synergistic effect of hybrid fillers with nanometric dimensions can be used to design high-performance natural rubber nanocomposites with enhanced electrical resistance and good cross-linking degree. (author)

Tuning of normal and inverse magnetocaloric effect in Sm{sub 0.35}Pr{sub 0.15}Sr{sub 0.5}MnO{sub 3} phase separated manganites

Energy Technology Data Exchange (ETDEWEB)

Giri, S.K. [Department of Physics, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India); Dasgupta, Papri; Poddar, A. [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, West Bengal (India); Nath, T.K., E-mail: tnath@phy.iitkgp.ernet.in [Department of Physics, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India)

2015-05-15

Graphical abstract: ΔS{sub M} vs. T plots of nano (left) and bulk (right) samples at different magnetic fields. - Highlights: • Bulk to nano show first order FM → PM phase transition at low magnetic field. • Bulk sample exhibits normal and inverse MCE around T{sub C} and after T{sub g}, respectively. • The value of ΔS{sub M} at T{sub C} is almost three times larger than at T{sub g}. • The value of ΔS{sub M} also decreases with reduction of particles sizes. • The bulk sample also exhibits a large RCP of 43.5 J/kg for a magnetic field of 1 T. - Abstract: Magnetic and magnetocaloric properties of Sm{sub 0.35}Pr{sub 0.15}Sr{sub 0.5}MnO{sub 3} polycrystalline manganite (bulk and nanometric samples) are investigated in detail. It has been observed that all the particle sizes (bulk to nano) show first order ferromagnetic → paramagnetic phase transition at low magnetic field. Ferromagnetic transition temperature also decreases with decreasing the particle size. This suggests that ferromagnetism is weakened and the first order magnetic phase transition is softened. We have investigated the magnetocaloric effect (MCE) of both bulk and nanometric samples around their spin glass-like transition temperature, T{sub g} and Curie temperature, T{sub C}. It has been found that bulk sample exhibits both normal (i.e., negative ΔS{sub M}) and inverse (i.e., positive ΔS{sub M}) MCE around T{sub C} and after T{sub g}, respectively. The value of ΔS{sub M} (+3.17 J kg{sup −1} K{sup −1}) at T{sub C} is almost three times larger than at T{sub g} (ΔS{sub M} = −0.52 J kg{sup −1} K{sup −1}) for a magnetic field change of 7 T. The bulk sample also exhibits a large relative cooling power (RCP) of 43.5 J/kg for a magnetic field of 1 T. The corresponding adiabatic temperature change of bulk sample is observed to be ∼1.5 K for a magnetic field change of 3 T. The value of ΔS{sub M} also decreases with reduction of particles sizes. The temperature width of ΔS{sub M

Crystal structure of superparamagnetic Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} nanoparticles synthesized by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Escamilla-Pérez, A.M., E-mail: angel.mep@gmail.com [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Cortés-Hernández, D.A., E-mail: dora.cortes@cinvestav.edu.mx [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Almanza-Robles, J.M. [Cinvestav-Unidad Saltillo, Industria Metalúrgica No. 1062, Parque Industrial Saltillo-Ramos Arizpe, C.P. 25900, Ramos Arizpe, Coahuila (Mexico); Mantovani, D.; Chevallier, P. [Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering and University Hospital Research Center, Laval University, Quebec City, QC (Canada)

2015-01-15

Powders of magnetic iron oxide nanoparticles (Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}) were prepared by a sol–gel method using ethylene glycol and nitrates of Fe, Ca and Mg as starting materials. Those powders were heat treated at different temperatures (573, 673, 773 and 873 K). In order to evaluate the effect of the heat treatment temperature on the nanoferrites properties, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used. It was found that the reaction products exhibit nanometric sizes and superparamagnetic behavior. It is also demonstrated that, as the heat treatment temperature increases, the particle size and the saturation magnetization of the nanoferrites are increased. - Highlights: • Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4} superparamagnetic nanoparticles were successfully synthesized. • Particle average sizes of Ca–Mg ferrites were within the range of 8–25 nm. • The nanoferrite treated at 873 K showed a stoichiometry close to Mg{sub 0.2}Ca{sub 0.8}Fe{sub 2}O{sub 4}. • The heat treatment temperature has a strong effect on the crystal structure. • These nanoparticles are potential materials for magnetic hyperthermia.

Nanometric onion-like hollow spheres in laser synthesized boron nitride ultrafine powder

Energy Technology Data Exchange (ETDEWEB)

Boulanger, L; Willaime, F [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees; Cauchetier, M [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche sur l` Etat Condense, les Atomes et les Molecules

1994-12-31

TEM observations of ultra-fine B Cl{sub 3}-N H{sub 3} powders elaborated by an innovative method, laser pyrolysis, are presented. The resulting microstructures in the as received state and after thermal treatments show small nanometric scale configurations close to the ones met with carbon, such as an hollowed configuration of onions but at a much smaller scale than with carbon. 3 figs., 3 refs.

Influence of ZnO nano-particles addition on thermal analysis, microstructure evolution and tensile behavior of Sn–5.0 wt% Sb–0.5 wt% Cu lead-free solder alloy

Energy Technology Data Exchange (ETDEWEB)

Fouda, A.N., E-mail: alynabieh@yahoo.com [Physics Department, Faculty of Science, Suez-Canal University, 41522 Ismailia (Egypt); Eid, E.A., E-mail: dr_eid_hti@yahoo.com [Basic Science Department, Higher Technological Institute, 44629 10th of Ramadan City (Egypt)

2015-04-24

Sn–5 wt%Sb–0.5 wt%Cu (plain SSC505) and Sn–5 wt%Sb–0.5 wt%Cu–0.5 wt% ZnO (SSC-ZnO) composite solder alloys have been studied. The variation in thermal behavior, microstructure and tensile characteristics associated with mixing of 0.5 wt% ZnO nano-metric particles to plain SSC505 solder were investigated. A slight increment in the melting temperature [ΔT{sub m}=0.89 °C] was recorded using differential scanning calorimetry (DSC) after addition of ZnO. X-Ray diffraction (XRD) analysis confirmed the existence of β-Sn, SbSn and Cu{sub 6}Sn{sub 5} intermetallic compounds (IMCs) beside some of ZnO planes in SSC-ZnO composite solder. Field emission scanning electronic microscope (FE-SEM) investigation of SSC-ZnO composite solder revealed a homogenous uniform distribution, size refinement of IMCs and β-Sn grains. Addition of ZnO nano-metric particles into the plain SSC505 enhanced the yield stress σ{sub YS} by ~12% and improved the ultimate tensile strength σ{sub UTS} by ~13%. In addition, adding ZnO nano-metric particles was found to be effective for reducing ductility by ~43% of the plain solder due to the refinement of β-Sn grains within SSC-ZnO composite solder. - Highlights: • Melting point of SSC505-ZnO composite solder is slightly increased by 0.89 {sup ο}C compared with the plain SSC505 solder. • XRD and EDX analysis reflect the presence of SbSn, Cu{sub 6}Sn{sub 5} IMCs. • EF-SEM images of SSC-ZnO composite solder revealed homogenous uniform distribution of β-Sn grains and fine IMC particles. • A detectable improvement in the Young modulus, ultimate tensile strength and yield strength were observed after addition of 0.5 wt% ZnO nano-metric particles.

Growth behavior of LiMn{sub 2}O{sub 4} particles formed by solid-state reactions in air and water vapor

Energy Technology Data Exchange (ETDEWEB)

Kozawa, Takahiro, E-mail: t-kozawa@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Yanagisawa, Kazumichi [Research Laboratory of Hydrothermal Chemistry, Faculty of Science, Kochi University, 2–5-1 Akebono-cho, Kochi 780-8520 (Japan); Murakami, Takeshi; Naito, Makio [Joining and Welding Research Institute, Osaka University, 11–1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

2016-11-15

Morphology control of particles formed during conventional solid-state reactions without any additives is a challenging task. Here, we propose a new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles based on water vapor-induced growth of particles during solid-state reactions. We have investigated the synthesis and microstructural evolution of LiMn{sub 2}O{sub 4} particles in air and water vapor atmospheres as model reactions; LiMn{sub 2}O{sub 4} is used as a low-cost cathode material for lithium-ion batteries. By using spherical MnCO{sub 3} precursor impregnated with LiOH, LiMn{sub 2}O{sub 4} spheres with a hollow structure were obtained in air, while angulated particles with micrometer sizes were formed in water vapor. The pore structure of the particles synthesized in water vapor was found to be affected at temperatures below 700 °C. We also show that the solid-state reaction in water vapor is a simple and valuable method for the large-scale production of particles, where the shape, size, and microstructure can be controlled. - Graphical abstract: This study has demonstrated a new strategy towards achieving morphology control without the use of additives during conventional solid-state reactions by exploiting water vapor-induced particle growth. - Highlights: • A new strategy to control the morphology of LiMn{sub 2}O{sub 4} particles is proposed. • Water vapor-induced particle growth is exploited in solid-state reactions. • The microstructural evolution of LiMn{sub 2}O{sub 4} particles is investigated. • The shape, size and microstructure can be controlled by solid-state reactions.

Engineering a new class of thermal spray nano-based microstructures from agglomerated nanostructured particles, suspensions and solutions: an invited review

Science.gov (United States)

Fauchais, P.; Montavon, G.; Lima, R. S.; Marple, B. R.

2011-03-01

From the pioneering works of McPherson in 1973 who identified nanometre-sized features in thermal spray conventional alumina coatings (using sprayed particles in the tens of micrometres size range) to the most recent and most advanced work aimed at manufacturing nanostructured coatings from nanometre-sized feedstock particles, the thermal spray community has been involved with nanometre-sized features and feedstock for more than 30 years. Both the development of feedstock (especially through cryo-milling, and processes able to manufacture coatings structured at the sub-micrometre or nanometre sizes, such as micrometre-sized agglomerates made of nanometre-sized particles for feedstock) and the emergence of thermal spray processes such as suspension and liquid precursor thermal spray techniques have been driven by the need to manufacture coatings with enhanced properties. These techniques result in two different types of coatings: on the one hand, those with a so-called bimodal structure having nanometre-sized zones embedded within micrometre ones, for which the spray process is similar to that of conventional coatings and on the other hand, sub-micrometre or nanostructured coatings achieved by suspension or solution spraying. Compared with suspension spraying, solution precursor spraying uses molecularly mixed precursors as liquids, avoiding a separate processing route for the preparation of powders and enabling the synthesis of a wide range of oxide powders and coatings. Such coatings are intended for use in various applications ranging from improved thermal barrier layers and wear-resistant surfaces to thin solid electrolytes for solid oxide fuel cell systems, among other numerous applications. Meanwhile these processes are more complex to operate since they are more sensitive to parameter variations compared with conventional thermal spray processes. Progress in this area has resulted from the unique combination of modelling activities, the evolution of

Nanometric holograms based on a topological insulator material.

Science.gov (United States)

Yue, Zengji; Xue, Gaolei; Liu, Juan; Wang, Yongtian; Gu, Min

2017-05-18

Holography has extremely extensive applications in conventional optical instruments spanning optical microscopy and imaging, three-dimensional displays and metrology. To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale. However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices. Here, we break this limit and achieve 60 nm holograms using a topological insulator material. We discover that nanometric topological insulator thin films act as an intrinsic optical resonant cavity due to the unequal refractive indices in their metallic surfaces and bulk. The resonant cavity leads to enhancement of phase shifts and thus the holographic imaging. Our work paves a way towards integrating holography with flat electronic devices for optical imaging, data storage and information security.

Improvement microstructural and damage characterization of ceramic composites Y{sub 2}O{sub 3} – V{sub 2}O{sub 5} with MgO nano particles

Energy Technology Data Exchange (ETDEWEB)

Issa, T. T., E-mail: alazbrh@yahoo.com; Hasan, J. M.; Abdullah, E. T. [University of Baghdad, College of Science, Physics Department, Jaderiha, Baghdad (Iraq); Shokr, F. S. [King Abdul Aziz Universit, Faculty of Science& Art, Physics Department, Rabigh, KSA (Saudi Arabia)

2016-04-21

Compacted samples of Y{sub 2}O{sub 3}-V{sub 2}O{sub 5} – MgO Nano – particles wt. % sintered at different sintering temperature (700, 900, 1100, 1300) ) C° for 2 hours under static air were investigated by x-ray diffraction and differential thermal analysis(DTA), to identify the phase present .Microstructure examination achieved by scanning electron microscopy .Sintered density and porosity were measured for all sintered samples .Compression was tested too and the Brake down voltage and dielectric strength were measure for all sintered samples .The clear improvement were noticed in both microstructure and damage characterization respectively after existing the MgO Nano-particles, by increasing in about 30% in sintered density and 25% for the compressive strength .The improvement also noticed on both brake down voltage and dielectric strength.

Accelerator and Technical Sector Seminar: Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution

CERN Multimedia

2011-01-01

Thursday 24 November 2010 Accelerator and Technical Sector Seminar at 14:15  -  BE Auditorium, bldg. 6 (Meyrin) – please note unusual place Mechanical stabilization and positioning of CLIC quadrupoles with sub-nanometre resolution Stef Janssens /EN-MME Abstract: To reach the required luminosity at the CLIC interaction point, about 4000 quadrupoles are needed to obtain a vertical beam size of 1 nm at the interaction point. The mechanical jitter of the quadrupole magnets will result in an emittance growth. An active vibration isolation system is required to reduce vibrations from the ground and from external forces to about 1.5 nm integrated root mean square (r.m.s.) vertical displacement at 1 Hz. A short overview of vibration damping and isolation strategies will be presented as well as a comparison of existing systems. The unprecedented resolution requirements and the instruments enabling these measurements will be discussed. The vibration sources from which the magnets need to...

Short range investigation of sub-micron zirconia particles

Energy Technology Data Exchange (ETDEWEB)

Caracoche, M C; Martinez, J A [Departamento de Fisica, IFLP, Facultad de Ciencias Exactas, CICPBA, Universidad Nacional de La Plata (Argentina); Rivas, P C [IFLP-CONICET, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata (Argentina); Bondioli, F; Cannillo, V [Dipartimento di Ingegniria dei Materiali e dell' Ambiente, Facolta di Ingegneria, Universita di Modena e Reggio Emilia (Italy); Ferrari, A M, E-mail: cristina@fisica.unlp.edu.a [Dipartimento di Scienza a Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia (Italy)

2009-05-01

The Perturbed Angular Correlations technique was used to determine the configurations around Zirconium ions and their thermal behavior in non-aggregated sub-micron zirconia spherical particles. Three residues containing- Zr surroundings were determined for the non-crystalline starting particles, which were identified under the assumption of a certain chemical reactions sequence during synthesis. While the one made up mainly by hydroxyl groups was common to both samples, the two involving mainly organic residues were particle size dependent. Upon crystallization, both samples stabilized in the t'- and t- tetragonal forms and the Xc-cubic form but their amounts and temperatures of appearance were different. On heating, the structure of the smaller particles became gradually monoclinic achieving total degradation upon the subsequent cooling to RT.

Engineering a new class of thermal spray nano-based microstructures from agglomerated nanostructured particles, suspensions and solutions: an invited review

International Nuclear Information System (INIS)

Fauchais, P; Montavon, G; Lima, R S; Marple, B R

2011-01-01

From the pioneering works of McPherson in 1973 who identified nanometre-sized features in thermal spray conventional alumina coatings (using sprayed particles in the tens of micrometres size range) to the most recent and most advanced work aimed at manufacturing nanostructured coatings from nanometre-sized feedstock particles, the thermal spray community has been involved with nanometre-sized features and feedstock for more than 30 years. Both the development of feedstock (especially through cryo-milling, and processes able to manufacture coatings structured at the sub-micrometre or nanometre sizes, such as micrometre-sized agglomerates made of nanometre-sized particles for feedstock) and the emergence of thermal spray processes such as suspension and liquid precursor thermal spray techniques have been driven by the need to manufacture coatings with enhanced properties. These techniques result in two different types of coatings: on the one hand, those with a so-called bimodal structure having nanometre-sized zones embedded within micrometre ones, for which the spray process is similar to that of conventional coatings and on the other hand, sub-micrometre or nanostructured coatings achieved by suspension or solution spraying. Compared with suspension spraying, solution precursor spraying uses molecularly mixed precursors as liquids, avoiding a separate processing route for the preparation of powders and enabling the synthesis of a wide range of oxide powders and coatings. Such coatings are intended for use in various applications ranging from improved thermal barrier layers and wear-resistant surfaces to thin solid electrolytes for solid oxide fuel cell systems, among other numerous applications. Meanwhile these processes are more complex to operate since they are more sensitive to parameter variations compared with conventional thermal spray processes. Progress in this area has resulted from the unique combination of modelling activities, the evolution of

Reduction under hydrogen of ferrite MFe{sub 2}O{sub 4} (M: Fe, Co, Ni) nanoparticles obtained by hydrolysis in polyol medium: A novel route to elaborate CoFe{sub 2}, Fe and Ni{sub 3}Fe nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ballot, N.; Schoenstein, F.; Mercone, S.; Chauveau, T.; Brinza, O. [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France); Jouini, N., E-mail: jouini@univ-paris13.fr [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France)

2012-09-25

Highlights: Black-Right-Pointing-Pointer Spinels nano-particles MFe{sub 2}O{sub 4} (M: Co, Fe or Ni) are obtained by hydrolysis in polyol medium. Black-Right-Pointing-Pointer Gentle reduction under hydrogen flow of spinel nano-particles yields metal and alloy nanoparticles. Black-Right-Pointing-Pointer TEM and X-ray analysis show that CoFe{sub 2}, Fe and Ni{sub 3}Fe nano-particles are monocrystalline particles with size less than 160 nm. Black-Right-Pointing-Pointer Iron with size of 150 nm presents ferromagnetic behavior. Black-Right-Pointing-Pointer CoFe{sub 2} alloy with size of 55 nm could be considered as a superparamagnetic material. - Abstract: A novel method to process metal and various alloy particles of nanometric size is described. The first step consists in the elaboration of MFe{sub 2}O{sub 4} (M: Fe, Ni or Co) spinel nanoparticles in polyol medium via hydrolysis and the second one in gently reducing these latter under hydrogen at 300 Degree-Sign C. X-ray diffraction analysis shows that pure Fe and CoFe{sub 2} alloy are well obtained by reducing Fe{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4}, respectively. This is not the case when we try to reduce NiFe{sub 2}O{sub 4}. A mixture of Fe and Ni{sub 3}Fe is observed. TEM analysis reveals that the size of metal particles stays within the range of a few tenths of nm up to 150 nm, while the precursors (MFe{sub 2}O{sub 4}) never exceed 5 nm. Our results show that the formation of metal particles occurs via two main steps: (i) reduction of the spinel oxide nanoparticles into metal ones and (ii) aggregation of the latter, leading to larger metal nanoparticles. Magnetic measurements indicate that the as-obtained metallic materials have good magnetic properties mainly affected by the sizes of the nanoparticles and the purity of the reduced phases.

Structural, morphological and luminescence properties of nanocrystalline up-converting Y{sub 1.89}Yb{sub 0.1}Er{sub 0.01}O{sub 3} phosphor particles synthesized through aerosol route

Energy Technology Data Exchange (ETDEWEB)

Lojpur, V.; Mancic, L. [Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, K. Mihailova 35/IV, 11000 Belgrade (Serbia); Rabanal, M.E. [University Carlos III of Madrid, Avd. Universidad 30, 28911 Leganes, Madrid (Spain); Dramicanin, M.D. [Vinca Institute of Nuclear Science, University of Belgrade, P.O. Box 522, Belgrade (Serbia); Tan, Z.; Hashishin, T.; Ohara, S. [JWRI, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Milosevic, O., E-mail: olivera.milosevic@itn.sanu.ac.rs [Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, K. Mihailova 35/IV, 11000 Belgrade (Serbia)

2013-12-15

Highlights: •The Y{sub 1.89}Yb{sub 0.1}Er{sub 0.01}O{sub 3} phosphor particles are synthesized via aerosol route. •We report influence of process parameters on the particle structure and morphology. •Spherical, submicronic size and nano-crystalline particle morphology are confirmed. •The particles show improved luminescence properties and decay time. •Synthesized powders exhibit the temperature dependant up-conversion emission. -- Abstract: Nanocrystalline up-converting Y{sub 2}O{sub 3}:Yb{sup 3+}, Er{sup 3+} phosphor particles were processed in a dispersed system-aerosol, generated ultrasonically at 1.3 MHz from common nitrate precursor solution having fixed ytterbium-to-erbium concentration ratio. The appropriate process parameters: residence time 21 s, carrier gas (air) flow rate 1.6 dm{sup 3}/min, synthesis temperature 900 °C, led to the formation of un-agglomerated spherical nanostructured secondary particles, having mean particle size of approx 450 nm, composed of primary nanoscaled (20 nm) subunits. In order to reach targeting phase crystallinity, the as-prepared particles were additionally annealed at 1100 °C in air for 12, 24 and 48 h, respectively. Particle structure, morphology and purity were analyzed by X-ray powder diffraction (XRPD), scanning electron microscopy (FESEM/SEM), analytical and high resolution transmission electron microscopy (TEM/HRTEM) in combination with energy dispersive X-ray analysis and Fourier Transform Infrared Spectroscopy (FTIR). All samples crystallized in a cubic bixbyte-structure, space group Ia-3. The crystallite size changed with annealing time from 30 nm in as-prepared sample to 135 nm in sample annealed for 48 h, respectively. Emission spectra were assigned to the following trivalent erbium f–f electronic transitions: {sup 2}H{sub 9/2} → {sup 4}I{sub 15/2} (blue: 407–420 nm), ({sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}) → {sup 4}I{sub 15/2} (green: 510–590 nm), and {sup 4}F{sub 9/2} → {sup 4}I{sub 15

Reactivity in the removal of SO{sub 2} and NO{sub x} on Co/Mg/Al mixed oxides derived from hydrotalcites

Energy Technology Data Exchange (ETDEWEB)

Palomares, A.E. [Department of Chemical and Nuclear Engineering, Universidad Politecnica Valencia, Avda. de los Naranjos s/n, 46022 Valencia (Spain); Lopez-Nieto, J.M.; Corma, A. [Instituto de Tecnologia Quimica, UPV-CSIC, Universidad Politecnica de Valencia, Avenida de los Naranjos s/n., 46022 Valencia (Spain); Lazaro, F.J.; Lopez, A. [Instituto Ciencia de Materiales de Aragon (CSIC- Universidad de Zaragoza), 50015 Zaragoza (Spain)

1999-04-05

Metal containing hydrotalcites, where metal oxides present redox properties and hydrotalcite shows a basic character, appear to be new important environmental catalysts for the removal of SO{sub x} and NO{sub x}. Redox and basic properties of a mixed Co/Mg/Al oxide derived from hydrotalcites are tuned in order to achieve the optimal catalytic behavior required. This sample has been characterized showing that cobalt is present in two forms, as isolated and well dispersed paramagnetic ions, and as very small Co-containing particles (in the nanometric range), with an internal antiferromagnetic ordering at low temperature. The redox properties of cobalt allow the reduction of NO with propane at high temperatures and in presence of oxygen. The reduced cobalt species are proposed as the active sites. Nevertheless, for the removal of SO{sub 2} and contrary to the case of Cu/Mg/Al samples, the addition of an oxidant as cerium oxide on Co/Mg/Al is necessary in order to oxidize SO{sub 2} to SO{sub 3}. In this case, similar results than those obtained with previously reported catalyst, i.e. cerium or copper-cerium hydrotalcite, are obtained. These results indicate that this catalyst could be an adequate material for the simultaneous removal of SO{sub 2} and NO{sub x} in a FCC unit

Synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} magnetic nanoparticles by thermal decomposition method for medical diagnosis applications

Energy Technology Data Exchange (ETDEWEB)

Sánchez, Javier, E-mail: h_javiersanchez@hotmail.com [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Reyes-Rodríguez, Pamela Yajaira; Jasso-Terán, Rosario Argentina [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico); Bartolo-Pérez, Pascual [CINVESTAV-IPN, Unidad Mérida, Departamento de Física Aplicada, A. P. 73 Cordemex, 97310 Mérida, Yuc., México (Mexico); De-León-Prado, Laura Elena [CINVESTAV-IPN, Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial Saltillo – Ramos Arizpe, Ramos Arizpe, Coahuila CP 25900, México (Mexico)

2017-04-01

In this work, the synthesis of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanosized particles by thermal decomposition method, using tetraethylene glycol (TEG) as a reaction medium, has been performed. The crystalline structure of the inverse spinel obtained in all the cases was identified by X-ray diffraction (XRD). Vibration sample magnetometry (VSM) was used to evaluate the magnetic properties of ferrites and to demonstrate their superparamagnetic behavior and the increase of magnetization values due to the Mn{sup 2+} ions incorporation into the FeGa{sub 2}O{sub 4} structure. Transmission electron microscopy, energy dispersive spectroscopy (TEM-EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the obtained magnetic nanoparticles (MNPs). These MNPs showed a near spherical morphology, an average particle size of 5.6±1.5 nm and a TEG coating layer on their surface. In all the cases MNPs showed no response when submitted to an alternating magnetic field (AMF, 10.2 kA/m, 354 kHz) using magnetic induction tests. These results suggest that the synthesized nanoparticles can be potential candidates for their use in biomedical areas. - Highlights: • Superparamagnetic NPs of Mn{sub x}Ga{sub 1−x}Fe{sub 2}O{sub 4} were synthesized by thermal decomposition. • Saturation magnetization of MnGaFe{sub 2}O{sub 4} increases as Mn ions are increased. • Nanoparticles have a nanometric size of 5.6 nm and show no heating ability.

SAP-like ultrafine-grained Al composites dispersion strengthened with nanometric AlN

International Nuclear Information System (INIS)

Balog, M.; Krizik, P.; Yan, M.; Simancik, F.; Schaffer, G.B.; Qian, M.

2013-01-01

This paper reports the development of novel Sinter-Aluminum-Pulver (SAP)-like Al–AlN nanocomposites via replacing the native Al 2 O 3 thin films on fine Al powder with a large volume fraction of in situ formed nanometric AlN dispersoids. Fine gas-atomized Al powder (d 50 =1.3 µm) compacts were first partially nitrided at 590 °C in flowing nitrogen, controlled by a small addition of Sn (0.3–0.4 wt%), and subsequently consolidated by hot direct extrusion. The resulting Al–AlN composites consisted of submicrometric Al grains reinforced with nanometric AlN dispersoids together with some nanometric Al 2 O 3 dispersoids. An Al–13 vol% AlN nanocomposite fabricated this way achieved exceptional ultimate tensile strength of 227 MPa, yield strength of 195 MPa and Young's modulus of 66 GPa at 300 °C, superior to typical SAP materials and coarse grained Al–AlN composites. In addition, the Al–13 vol% AlN nanocomposite exhibited good thermal stability up to 500 °C. The strengthening mechanism is discussed

Optimization of Ru{sub x}Se{sub y} electrocatalyst loading for oxygen reduction in a PEMFC

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Huerta, R.G. [Instituto Politecnico Nacional, Laboratorio de Electroquimica y Corrosion ESIQIE, UPALP, 07738 Mexico, D.F., Mexico (Mexico); Guzman-Guzman, A.; Solorza-Feria, O. [Depto. Quimica, Centro de Investigacion y de Estudios Avanzados del IPN, A. Postal 14-740, 07360 Mexico D.F., Mexico (Mexico)

2010-11-15

The synthesis, characterization and optimization of Ru{sub x}Se{sub y} catalyst loading as a cathode electrode for a single polymer electrolyte membrane fuel cell, PEMFC were investigated. Ru{sub x}Se{sub y} catalyst was synthesized via a decarbonylation of Ru{sub 3}(CO){sub 12} and elemental selenium in 1,6-hexanediol under refluxing conditions for 2 h. The powder electrocatalyst was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and examined for the oxygen reduction reaction (ORR) in 0.5M H{sub 2}SO{sub 4} by rotating disk electrode (RDE) and in membrane-electrode assemblies, MEAs for a single PEMFC. Results indicate the formation of agglomerates of crystalline particles with nanometric size embedded in an amorphous phase. The catalyst exhibited high current density and lower overpotential for the ORR compared to that of Ru{sub x} cluster catalyst. Dispersed Ru{sub x}Se{sub y} catalyst loading on Vulcan carbon was optimized as a cathode electrode by performance testing in a single H{sub 2}-O{sub 2} fuel cell. (author)

Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

Directory of Open Access Journals (Sweden)

Matus K.

2016-06-01

Full Text Available The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.

Polycrystalline Nd{sub 2}Fe{sub 14}B/α-Fe nanocomposite flakes with a sub-micro/nanometre thickness prepared by surfactant-assisted high-energy ball milling

Energy Technology Data Exchange (ETDEWEB)

Tang, Xin, E-mail: tangshincn@gmail.com [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Chen, Xi [Mechanical and Electrical Engineering College, Xinxiang University, No. 192, Jinsui Road, Xinxiang, Henan 453003 (China); Chen, Renjie; Yan, Aru [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2015-09-25

Highlights: • Nd{sub 2}Fe{sub 14}B/α-Fe flakes are formed by peeling along preferential planes. • (0 0 l) planes are found to be preferential cleavage planes. • Magnetic properties degrade with increasing ball milling time. • Anisotropic nanocomposite magnets are fabricated. - Abstract: A surfactant-assisted high-energy ball milling technique was employed to synthesize Nd{sub 2}Fe{sub 14}B/α-Fe nanoparticles and nanoflakes from melt-spun nanocrystalline powders. The microstructure evolution in ball milling process was investigated. In the beginning stage (0–4 h) of ball milling, raw powders were crushed into micrometre-sized particles. While flakes were mainly formed by reducing thickness of particles via peeling layer by layer along preferential planes in the late stage (8–16 h). The selected area electron diffraction and high-resolution transmission electron microscopy images show that preferential cleavage planes are basal planes. With ball milling proceeding, more and more defects were induced by ball milling. As a result, the coercivity and remanence decreased to 1.6 kOe and 3.2 kGs, respectively. After 16 h ball milling, the exchange decoupling occurred due to severe amorphorization. A weakly-textured nanocomposite magnet was fabricated after 12 h ball milling and the anisotropy in magnetic properties can be further improved by employing settling down process to select particle size and aligning particles in external field.

Resistance of Type 5 chemical protective clothing against nanometric airborne particles: Behavior of seams and zipper.

Science.gov (United States)

Vinches, Ludwig; Hallé, Stéphane

2017-12-01

In the field of dermal protection, the use of chemical protective clothing (CPC) (including coveralls) are considered as the last barrier against airborne engineered nanomaterials (ENM). In the majority of cases, Type 5 CPC, used against solid particles (ISO 13982-1), perform well against ENM. But in a recent study, a penetration level (PL) of up to 8.5% of polydisperse sodium chloride airborne nanoparticles has been measured. Moreover, in all the previous studies, tests were performed on a sample of protective clothing material without seams or zippers. Thus, the potential for permeation through a zipper or seams has not yet been determined, even though these areas would be privileged entry points for airborne ENM. This work was designed to evaluate the PL of airborne ENM through coveralls and specifically the PL through the seams on different parts of the CPC and the zipper. Eight current models of CPC (Type 5) were selected. The samples were taken from places with and without seams and with a zipper. In some cases, a cover strip can be added to the zipper to enhance its sealing. Polydisperse nanoparticles were generated by nebulization of a sodium chloride solution. A penetration cell was developed to expose the sample to airborne nanometric particles. The NaCl particle concentration in number was measured with an ultrafine particle counter and the PL was defined as the downstream concentration divided by the upstream concentration. The results obtained show that the PL increased significantly in the presence of seams and could reach up to 90% depending on the seam's design. Moreover, this study classifies the different types of seams by their resistance against airborne ENM. As for the penetration of airborne NaCl particles through the zipper, the PL was greatly attenuated by the presence of a cover strip, but only for certain models of coveralls. Finally, the values of the pressure drop were directly linked to the type of seam. All of these conclusions provide

Evaluation of H{sub 2}O{sub 2}-generation during oxygen reduction at electrodeposited Pt particles on mask scratched electrodes

Energy Technology Data Exchange (ETDEWEB)

Kishi, Akira; Inoue, Mitsuhiro; Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp

2013-08-15

In this study, the Pt particle deposition was systematically performed by our proposed mask scratch and subsequent Pt electrodeposition in order to investigate the H{sub 2}O{sub 2}-byproduct generation efficiency during O{sub 2} reduction. By peeling a part of polymer layer coated on a glassy carbon substrate using an atomic force microscope cantilever, scratched areas are regularly made. The Pt particles are deposited only on the above-mentioned scratched areas, indicating that the controlled Pt deposition has been achieved. The background cyclic voltammetry of the prepared electrodes showed that the deposited nanoparticles are certainly composed of Pt. Moreover, the electrochemical surface area of the deposited Pt (Pt-ESA) linearly increases with the increasing scratched area, revealing that the Pt-ESAs can be controlled by the mask scratch-based Pt electrodeposition method. It should be noted that an increase in the Pt-ESA not only increases the O{sub 2} reduction currents, but also enhances the H{sub 2}O{sub 2} generation efficiency.

Low field magnetoresistance effects in fine particles of La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3 perovskites

CERN Document Server

Rivas, J; Fondado, A; Rivadulla, F; López-Quintela, M A

2000-01-01

In this work magnetic and magnetotransport experimental data in well-characterized small particles of La sub 0 sub . sub 6 sub 7 Ca sub 0 sub . sub 3 sub 3 MnO sub 3 are presented. Grain size reduction leads to a larger resistivity and a decrease in metal-insulator transition temperature. Intrinsic colossal magnetoresistance (CMR) is destroyed while intergranular one is promoted to larger values. This low field MR can be explained taking into account magnetization data through spin-polarized tunneling model, which ensures an acceptable first-order fit between both magnitudes. Finally, low-temperature resistivity upturn present in small particle size samples can be understood in terms of an electrostatic barrier between grains.

Particles on surfaces of laser ablated Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films

Energy Technology Data Exchange (ETDEWEB)

Zheng, X.Y.; Zhu, S. [Tennessee Univ., Knoxville, TN (United States); Lowndes, D.H.; Warmack, R.J. [Oak Ridge National Lab., TN (United States)

1993-09-01

Pulsed laser deposition of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films grown at heater temperature of 720 and 800 C on SrTiO{sub 3} and MgO substrates with thickness ranging from a nominal 5 unit cells to 200 nm were studied by STM and SEM. Size and density of particles present in the films were found to depend on film thickness, growth temperature and substrate. STM images indicate a correlation between film growth mode and particle density: the onset of big particles comes after the growth mode changes from layer-like to island growth.

Preparation of Cr{sub 2}O{sub 3} nanoparticles for superthermites by the detonation of an explosive nanocomposite material

Energy Technology Data Exchange (ETDEWEB)

Comet, Marc, E-mail: marc.comet@isl.eu; Pichot, Vincent; Siegert, Benny; Fousson, Eric [NS3E, UMR 3208 ISL/CNRS, French-German Research Institute of Saint-Louis (ISL) (France); Mory, Julien; Moitrier, Florence [French-German Research Institute of Saint-Louis (ISL) (France); Spitzer, Denis [NS3E, UMR 3208 ISL/CNRS, French-German Research Institute of Saint-Louis (ISL) (France)

2011-05-15

This article reports on the preparation of chromium(III) oxide nanoparticles by detonation. For this purpose, a high explosive-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-has been solidified from a solution infiltrated into the macro- and mesoporosity of Cr{sub 2}O{sub 3} powder obtained by the combustion of ammonium dichromate. The resulting Cr{sub 2}O{sub 3}/RDX nanocomposite material was embedded in a cylindrical charge of pure explosive and detonated in order to fragment the metallic oxide into nanoparticles. The resulting soot contains Cr{sub 2}O{sub 3} nanoparticles, nanodiamonds, amorphous carbon species and inorganic particles resulting from the erosion by the blast of the detonation tank wall. The purification process consists in (i) removing the carbonaceous species by an oxidative treatment at 500 Degree-Sign C and (ii) dissolving the mineral particles by a chemical treatment with hydrofluoric acid. Contrary to what could be expected, the Cr{sub 2}O{sub 3} particles formed during the detonation are twice larger than those of initial Cr{sub 2}O{sub 3}. The detonation causes the fragmentation of the porous oxide and the melting of resulting particles. Nanometric droplets of molten Cr{sub 2}O{sub 3} are ejected and quenched by the water in which the charge is fired. Despite their larger size, the Cr{sub 2}O{sub 3} nanoparticles prepared by detonation were found to be less aggregated than those of the initial oxide used as precursor. Finally, the Cr{sub 2}O{sub 3} synthesized by detonation was used to prepare a superthermite with aluminium nanoparticles. This material possesses a lower sensitivity and a more regular combustion compared to the one made of initial Cr{sub 2}O{sub 3}.

Synthesis and characterization of nanosized Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} ferrites by both sol-gel and thermal decomposition methods

Energy Technology Data Exchange (ETDEWEB)

De-León-Prado, Laura Elena, E-mail: laura.elena.prado@gmail.com [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Cortés-Hernández, Dora Alicia; Almanza-Robles, José Manuel; Escobedo-Bocardo, José Concepción; Sánchez, Javier; Reyes-Rdz, Pamela Yajaira; Jasso-Terán, Rosario Argentina [Cinvestav-Unidad Saltillo, Av. Industria Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, Ramos Arizpe, Coahuila, México (Mexico); Hurtado-López, Gilberto Francisco [Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo #140, CP 25294, Saltillo, Coahuila, México (Mexico)

2017-04-01

This work reports the synthesis of Mg{sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} (x=0–1) nanoparticles by both sol-gel and thermal decomposition methods. In order to determine the effect of synthesis conditions on the crystal structure and magnetic properties of the ferrites, the synthesis was carried out varying some parameters, including composition. By both methods it was possible to obtain ferrites having a single crystalline phase with cubic inverse spinel structure and a behavior near to that of superparamagnetic materials. Saturation magnetization values were higher for materials synthesized by sol-gel. Furthermore, in both cases particles have a spherical-like morphology and nanometric sizes (11–15 nm). Therefore, these materials can be used as thermoseeds for the treatment of cancer by magnetic hyperthermia. - Highlights: • Mg–Mn ferrites were synthesized by sol-gel and thermal decomposition methods. • Materials showed a single cubic inverse spinel crystalline structure. • Ferrites have a soft ferrimagnetic behavior close to superparamagnetic materials.

Highly dispersed spherical Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12} nanocrystals via topotactic crystallization of aggregation-free gel particles from an effective inverse miniemulsion sol–gel approach

Energy Technology Data Exchange (ETDEWEB)

Wang, Aijun; Zeng, Yanwei, E-mail: zengyw-njut@126.com, E-mail: stephen-zeng@njtech.edu.cn, E-mail: stephen-zeng@163.com; Han, Longxiang; Ding, Chuan; Cao, Liangliang; Li, Rongjie [Nanjing Tech University, State Key Laboratory of Materials-Oriented Chemical Engineering, College of Materials Science and Engineering (China)

2015-09-15

Aggregation-free spherical lanthanum-doped bismuth titanate (Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12}, BLT) gel particles with an average size of about 150 nm were successfully obtained from an inverse miniemulsion sol–gel process, with Span-80 acting as surfactant, n-butanol as co-surfactant, cyclohexane as continuous phase, and submicro-droplets of aqueous solution containing Bi{sup 3+}, La{sup 3+} and Ti{sup 4+} ions as dispersed phase, and then topotactically transformed into highly dispersed spherical BLT nanocrystals after an in situ crystallization at 600 °C for 8 h. It has been found that the BLT gel particles can be obtained via a moderate sol–gel reaction inside the miniemulsion droplets at 65 °C, but their morphology and aggregation degree are strongly affected by the relative amounts of Span-80 and n-butanol. The perfect spherical BLT gel particles with no aggregation can be achieved only under the condition of 3 wt% n-butanol relative to the mass of cyclohexane, with excessive amount of n-butanol leading to the formation of ill-gelled particles with irregular shapes, while insufficient addition of n-butanol resulting in terrible aggregation of gel particles. To understand the formation of aggregation-free spherical BLT gel particles, a tentative mechanism is proposed and discussed, which reveals that a well-coordinated oil–water interfacial film made up of Span-80 and n-butanol molecules and the appropriately enhanced evaporation of water from such interfaces should be responsible for the formation of aggregation-free spherical BLT gel particles. Graphical Abstract: Aggregation-free spherical BLT (Bi{sub 3.25}La{sub 0.75}Ti{sub 3}O{sub 12}) gel particles can be prepared from an effective inverse miniemulsion sol–gel process, and subsequently topotactically transformed into spherical BLT nanocrystals through an in situ crystallization.

Solar photocatalytic activity of TiO{sub 2} modified with WO{sub 3} on the degradation of an organophosphorus pesticide

Energy Technology Data Exchange (ETDEWEB)

Ramos-Delgado, N.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Gracia-Pinilla, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas, Av. Universidad, Cd. Universitaria, San Nicolás de los Garza, N.L. (Mexico); Universidad Autónoma de Nuevo León, Centro de Investigación e Innovación en Desarrollo de Ingeniería y Tecnología, PIIT Km 6, Carretera al Aeropuerto, Apodaca, N.L. (Mexico); Maya-Treviño, L.; Hinojosa-Reyes, L.; Guzman-Mar, J.L. [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico); Hernández-Ramírez, A., E-mail: aracely.hernandezrm@uanl.edu.mx [Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, San Nicolás de los Garza, N.L. (Mexico)

2013-12-15

Highlights: • TiO{sub 2} and WO{sub 3}/TiO{sub 2} (2 and 5%) were tested in the photocatalytic malathion degradation. • The use of solar radiation in the photocatalytic degradation process was evaluated. • Modified catalyst showed greater photocatalytic activity than pure TiO{sub 2}. • The mineralization rate was improved when WO{sub 3} content on TiO{sub 2} was 2%. -- Abstract: In this study, the solar photocatalytic activity (SPA) of WO{sub 3}/TiO{sub 2} photocatalysts synthesized by the sol–gel method with two different percentages of WO{sub 3} (2 and 5%wt) was evaluated using malathion as a model contaminant. For comparative purpose bare TiO{sub 2} was also prepared by sol–gel process. The powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance UV–vis spectroscopy (DRUV–vis), specific surface area by the BET method (SSA{sub BET}), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy with a high annular angle dark field detector (STEM-HAADF). The XRD, Raman, HRTEM and STEM-HAADF analyses indicated that WO{sub 3} was present as a monoclinic crystalline phase with nanometric cluster sizes (1.1 ± 0.1 nm for 2% WO{sub 3}/TiO{sub 2} and 1.35 ± 0.3 nm for 5% WO{sub 3}/TiO{sub 2}) and uniformly dispersed on the surface of TiO{sub 2}. The particle size of the materials was 19.4 ± 3.3 nm and 25.6 ± 3 nm for 2% and 5% WO{sub 3}/TiO{sub 2}, respectively. The SPA was evaluated on the degradation of commercial malathion pesticide using natural solar light. The 2% WO{sub 3}/TiO{sub 2} photocatalyst exhibited the best photocatalytic activity achieving 76% of total organic carbon (TOC) abatement after 300 min compared to the 5% WO{sub 3}/TiO{sub 2} and bare TiO{sub 2} photocatalysts, which achieved 28 and 47% mineralization, respectively. Finally, experiments were performed to assess 2% WO{sub 3}/TiO{sub 2} catalyst activity on

Influence of nanometric silicon carbide on phenolic resin composites ...

Indian Academy of Sciences (India)

Abstract. This paper presents a preliminary study on obtaining and characterization of phenolic resin-based com- posites modified with nanometric silicon carbide. The nanocomposites were prepared by incorporating nanometric silicon carbide (nSiC) into phenolic resin at 0.5, 1 and 2 wt% contents using ultrasonication to ...

Influence of nanometric silicon carbide on phenolic resin composites

Indian Academy of Sciences (India)

The results highlight the positive effect of the nanometric silicon carbide addition in phenolic resin on mechanical, thermo-mechanical and tribological performance, improving their strength, stiffness and abrasive properties. The best results were obtained for 1 wt% nSiC, proving that this value is the optimum nanometric ...

On the mechanisms of titanium particle reactions in O{sub 2}/N{sub 2} and O{sub 2}/Ar atmospheres

Energy Technology Data Exchange (ETDEWEB)

Andrzejak, Timothy A.; Shafirovich, Evgeny; Varma, Arvind [School of Chemical Engineering, Purdue University, West Lafayette, IN (United States)

2009-02-15

Combustion of titanium particles in air may potentially be used for the in situ synthesis of nanoscale TiO{sub 2} particles, which can photocatalytically degrade chemical and biological air pollutants. The knowledge of Ti particle reactions in O{sub 2}-containing atmospheres is required to develop this method. In the present work, large ({proportional_to}3 mm) single Ti particles were heated by a laser in O{sub 2}/N{sub 2} and O{sub 2}/Ar environments. High-speed digital video recording, thermocouple measurements and quenching at different stages of the process were used for diagnostics. Analysis of the obtained temperature-time curves and quenched particles does not show a significant influence of nitrogen on the oxidation of solid Ti. In all experiments, noticeable surface oxidation started at temperatures between {proportional_to}850 and {proportional_to}950 C, leading to a sharp temperature rise at {proportional_to}1400 C. During prolonged heating at the Ti melting point (1670 C), a liquid TiO{sub 2} bead formed and, after an induction period, ejected fragments. It was shown that this phenomenon may result from an excess of oxygen in the liquid bead. Fragment ejection in O{sub 2}/N{sub 2} atmospheres was more intense than in O{sub 2}/Ar, indicating that N{sub 2} accelerates the oxidation of liquid Ti. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Theoretical and experimental studies of single event effect induced by atmospheric muons on nano-metric technologies

International Nuclear Information System (INIS)

Li Cavoli, P.

2016-01-01

This study concerns the domain of the microelectronics. It consists in the study of the impact of the 3D morphology of the energy deposit on the Single Event Effect (SEE) modeling, induced by atmospheric muons. Over a first phase, the approach has consisted in the modeling of the energy deposit induced by protons in nano-metric volumes. For that purpose the use of the Monte Carlo code GEANT4 has allowed us to simulate and stock in a database the tracks characteristics of the energy deposit induced by protons. Once the approach validated for the protons, simulations of the energy deposit induced by muons have been realized. A CCD camera has been used in order to measure the radiative atmospheric environment and to constrain the modeling of the energy deposit induced by muons. This study highlights and quantify the contribution of the radial distribution of the energy deposit induced by protons in nano-metric volumes for the SEE prediction. On the other hand, the study shows that the contribution of the radial distribution of the energy deposit induced by muons in nano-metric volumes has a negligible impact on the SEE modeling. It will be interesting to realize measurements of the energy deposit induced by muons in nano-metric technologies under particle accelerator. This will allow to bring experimental data still nonexistent necessary to the development of new physical models more accurate on the modeling of the energy deposit induced by muons. (author)

Photon event distribution sampling: an image formation technique for scanning microscopes that permits tracking of sub-diffraction particles with high spatial and temporal resolutions.

Science.gov (United States)

Larkin, J D; Publicover, N G; Sutko, J L

2011-01-01

In photon event distribution sampling, an image formation technique for scanning microscopes, the maximum likelihood position of origin of each detected photon is acquired as a data set rather than binning photons in pixels. Subsequently, an intensity-related probability density function describing the uncertainty associated with the photon position measurement is applied to each position and individual photon intensity distributions are summed to form an image. Compared to pixel-based images, photon event distribution sampling images exhibit increased signal-to-noise and comparable spatial resolution. Photon event distribution sampling is superior to pixel-based image formation in recognizing the presence of structured (non-random) photon distributions at low photon counts and permits use of non-raster scanning patterns. A photon event distribution sampling based method for localizing single particles derived from a multi-variate normal distribution is more precise than statistical (Gaussian) fitting to pixel-based images. Using the multi-variate normal distribution method, non-raster scanning and a typical confocal microscope, localizations with 8 nm precision were achieved at 10 ms sampling rates with acquisition of ~200 photons per frame. Single nanometre precision was obtained with a greater number of photons per frame. In summary, photon event distribution sampling provides an efficient way to form images when low numbers of photons are involved and permits particle tracking with confocal point-scanning microscopes with nanometre precision deep within specimens. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

Extruded Al-Al{sub 2}O{sub 3} composites formed in situ during consolidation of ultrafine Al powders: Effect of the powder surface area

Energy Technology Data Exchange (ETDEWEB)

Balog, Martin, E-mail: martin.balog@savba.sk [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Bratislava (Slovakia); Simancik, Frantisek [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Bratislava (Slovakia); Walcher, Martin; Rajner, Walter [NMD - New Materials Development GmbH, St. Pantaleon (Austria); Poletti, Cecilia [Institute of Materials Science and Welding, Graz University of Technology, Kopernikusgasse 24/I, A8010 Graz (Austria)

2011-11-25

Highlights: {yields} 25 gas atomised Al 99.5% powders with particle size <10 {mu}m were hot extruded. {yields} The strength of compacts was closely related to powder surface area. {yields} Grain boundary strengthening was enhanced by the presence of in situ Al{sub 2}O{sub 3} dispersoids. {yields} Compacts showed good thermal stability due to grain pinning of Al{sub 2}O{sub 3} dispersoids. - Abstract: Twenty-five samples of commercially available, gas-atomised Al (99.5%) powders with particle sizes <10 {mu}m were hot extruded into Al-Al{sub 2}O{sub 3} composites formed in situ during extrusion. The effect of particle size, surface area, oxygen content and atomisation atmosphere of the powder on the microstructure and mechanical properties of the extruded compacts were studied by Brunauer, Emmett, Teller (BET) analysis, hot gas extraction, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. Thermal stability of the compacts and the individual strengthening mechanisms operating in the compacts were discussed. It was found that the properties of the compacts stemmed from the extraordinary grain boundary strengthening effect of the ultrafine-grained compacts due to their microstructures. The efficiency of the grain boundary strengthening was significantly enhanced by the presence of nano-metric Al{sub 2}O{sub 3} dispersoids introduced in situ. The strength of the compacts was closely related to the surface area of the powder particles. In addition, the entrapped gasses and chemically bonded humidity had a negative effect on the mechanical properties of the compacts.

Experimental equivalent cluster-size distributions in nano-metric volumes of liquid water

International Nuclear Information System (INIS)

Grosswendt, B.; De Nardo, L.; Colautti, P.; Pszona, S.; Conte, V.; Tornielli, G.

2004-01-01

Ionisation cluster-size distributions in nano-metric volumes of liquid water were determined for alpha particles at 4.6 and 5.4 MeV by measuring cluster-size frequencies in small gaseous volumes of nitrogen or propane at low gas pressure as well as by applying a suitable scaling procedure. This scaling procedure was based on the mean free ionisation lengths of alpha particles in water and in the gases measured. For validation, the measurements of cluster sizes in gaseous volumes and the cluster-size formation in volumes of liquid water of equivalent size were simulated by Monte Carlo methods. The experimental water-equivalent cluster-size distributions in nitrogen and propane are compared with those in liquid water and show that cluster-size formation by alpha particles in nitrogen or propane can directly be related to those in liquid water. (authors)

Control of the Shell Thickness of TiO{sub 2} SiO{sub 2} Particles and Its Surface Functionalization

Energy Technology Data Exchange (ETDEWEB)

Ahn, Junho; Jung, Sung Ho; Lee, Ji Ha; Kwon, Kiyoung; Jung, Jong Hwa [Gyeongsang National Univ., Jinju (Korea, Republic of)

2013-11-15

TiO{sub 2} SiO{sub 2} yolk/core shell particles were obtained by a sol-gel polymerization. The shell thickness of TiO{sub 2} SiO{sub 2} can successfully be controlled by sol-gel reaction times. The anatase structure of TiO{sub 2} SiO{sub 2} was more stable than that of TiO{sub 2} particles calcinated at higher temperature. Moreover, acrylate-functionalized TiO{sub 2} SiO{sub 2} particles were also successfully synthesized using the TiO{sub 2} SiO{sub 2} particles as building blocks by copolymerization of trimethoxysilyl groups of MPA with the existing hydroxyl groups on the surface of TiO{sub 2} SiO{sub 2} particles. Furthermore, TEM, EDX, and FTIR studies confirmed that MPA had been successfully grafted to the surface of TiO{sub 2} SiO{sub 2} particles. Finally, we believe that the present results showing the development of surface functionalized particles can be very useful in the fields of various functional applications, and could be extended to more sophisticated hybrid materials.The fabrication of functional hollow particles is of great scientific and technological interest for purposes of applications ranging from drug delivery, coatings, photonic devices, and nanoscale reaction vessels. Various methods, including approaches such as spray drying, emulsion templating techniques, and self-assembly processes, have been described for the preparation of hollow spheres out of latex, metal, and inorganic materials.

Simulation of YBa{sub 2}Cu{sub 3}O{sub 7}/MgO surface growth

Energy Technology Data Exchange (ETDEWEB)

Mohammadizadeh, M.R. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran); Computational Physical Sciences Research Laboratory, Department of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran); Safari, N.; Kia, M.; Savaloni, H. [Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, North Karegar Ave., P.O. Box 14395-547, Tehran (Iran)

2006-09-15

For surface growth simulation of YBa{sub 2}Cu{sub 3}O{sub 7} 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 YBa{sub 2}Cu{sub 3}O{sub 7} 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.)

Synthesis, microstructure and magnetic properties of Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core

Energy Technology Data Exchange (ETDEWEB)

Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

2015-11-15

Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core have been synthesized via a modified stöber method combined with following high temperature sintering process. Most of conductive Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by insulating SiO{sub 2} using the modified stöber method. The Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles exhibited good soft magnetic properties with low coercivity and high saturation magnetization. The reaction 4Al+3SiO{sub 2}=2α-Al{sub 2}O{sub 3}+3Si took place during the sintering process. As a result the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite core displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher electrical resistivity and lower core loss than the pure Fe{sub 3}Si{sub 0.7}Al{sub 0.3} core. The method of introducing insulating layers surrounding magnetic particles provides a promising route to develop new and high compact soft magnetic materials with good magnetic and electric properties. - Graphical abstract: In Fe{sub 3}Si/Al{sub 2}O{sub 3} composite, Fe{sub 3}Si phases are separated by Al{sub 2}O{sub 3} layers and the eddy currents are confined in Fe{sub 3}Si phases, thus increasing resistivity and reducing core loss. - Highlights: • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores were prepared. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by nano-sized SiO{sub 2} clusters. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores showed good soft magnetic properties. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than Fe{sub 3}Si{sub 0.7}Al{sub 0.3} cores.

Evaluation of Microflow Digital Imaging Particle Analysis for Sub-Visible Particles Formulated with an Opaque Vaccine Adjuvant.

Directory of Open Access Journals (Sweden)

Grant E Frahm

Full Text Available Microflow digital imaging (MDI has become a widely accepted method for assessing sub-visible particles in pharmaceutical formulations however, to date; no data have been presented on the utility of this methodology when formulations include opaque vaccine adjuvants. This study evaluates the ability of MDI to assess sub-visible particles under these conditions. A Fluid Imaging Technologies Inc. FlowCAM® instrument was used to assess a number of sub-visible particle types in solution with increasing concentrations of AddaVax™, a nanoscale squalene-based adjuvant. With the objective (10X used and the limitations of the sensor resolution, the instrument was incapable of distinguishing between sub-visible particles and AddaVax™ droplets at particle sizes less than 5 μm. The instrument was capable of imaging all particle types assessed (polystyrene beads, borosilicate glass, cellulose, polyethylene protein aggregate mimics, and lysozyme protein aggregates at sizes greater than 5 μm in concentrations of AddaVax™ up to 50% (vol:vol. Reduced edge gradients and a decrease in measured particle sizes were noted as adjuvant concentrations increased. No significant changes in particle counts were observed for polystyrene particle standards and lysozyme protein aggregates, however significant reductions in particle counts were observed for borosilicate (80% of original and cellulose (92% of original particles. This reduction in particle counts may be due to the opaque adjuvant masking translucent particles present in borosilicate and cellulose samples. Although the results suggest that the utility of MDI for assessing sub-visible particles in high concentrations of adjuvant may be highly dependent on particle morphology, we believe that further investigation of this methodology to assess sub-visible particles in challenging formulations is warranted.

Surface modification of submicronic TiO{sub 2} particles prepared by ultrasonic spray pyrolysis for visible light absorption

Energy Technology Data Exchange (ETDEWEB)

Dugandzic, Ivan M. [Institute of Technical Sciences of SASA (Serbia); Jovanovic, Dragana J. [University of Belgrade, Vinca Institute of Nuclear Sciences (Serbia); Mancic, Lidija T. [Institute of Technical Sciences of SASA (Serbia); Zheng, Nan; Ahrenkiel, Scott P. [South Dakota School of Mines and Technology (United States); Milosevic, Olivera B. [Institute of Technical Sciences of SASA (Serbia); Saponjic, Zoran V.; Nedeljkovic, Jovan M., E-mail: jovned@vinca.rs [University of Belgrade, Vinca Institute of Nuclear Sciences (Serbia)

2012-10-15

Spherical, submicronic TiO{sub 2} assemblage with high specific surface area and controllable phase composition was prepared in the process of ultrasonic spray drying/pyrolysis in a wide temperature range (150-800 Degree-Sign C) by using as a precursor aqueous colloidal solution consisting of TiO{sub 2} nanoparticles (4.5 nm). Submicronic, soft and grained spherical TiO{sub 2} particles (d = 370-500 nm) comprising clustered nanocrystals (<10 nm) were obtained at low processing temperature, while particle densification, intensive growth of the clustered primary units and anatase-to-rutile transformation ({approx}30 wt%) were observed at the higher temperatures. Detailed structural and morphological characterisation were performed by X-ray powder diffraction, scanning and field emission electron microscopy, transmission electron microscopy, and laser particle size analysis. Moreover, the surface modification of TiO{sub 2} particles through the formation of charge-transfer (CT) complex was achieved with different ligands: ascorbic acid, dopamine, catechol, 2,3-dihydroxynaphthalene, and anthrarobin. Optical properties of the surface-modified TiO{sub 2} particles were studied by using diffuse reflection spectroscopy. The binding structure between the surface titanium atoms and different ligands was determined by using Fourier transform infrared spectroscopy. The formation of CT complexes induced significant red shift of optical absorption in comparison to unmodified TiO{sub 2} particles.

Spectral evolution of Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate induced by temperature

Energy Technology Data Exchange (ETDEWEB)

Kim, K-Y.; Durand, A. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Heintz, J-M.; Veillere, A. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Bordeaux INP, ICMCB, UPR 9048, F-33600 Pessac (France); Jubera, V., E-mail: veronique.jubera@u-bordeaux.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

2016-03-15

A Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate powder was synthetized using a polymerizable complex route. It gave rise to nanometric particles that crystallized in the fluorine structure, corresponding to the Y{sub 3}NbO{sub 7} phase. The thermal evolution of this powder was followed up to 1600 °C, using X-ray diffraction and optical characterizations. The fluorine structure was maintained in the whole temperature range. However, spectral evolution of the samples calcined above 900 °C showed a more complex situation. Emission spectra of powders heat treated at different temperatures showed an evolution of the emission lines that can be attributed first to a better crystallization of the niobate phase and second to its partial decomposition in favor of the formation of YNbO{sub 4} and Y{sub 2}O{sub 3}. Although the Y{sub 3}NbO{sub 7} phase appeared stable up to 1650 °C, from X-ray diffraction analysis, spectral analysis showed that the local environment of the doping element is modified from 1100 °C. - Graphical abstract: Spectral evolution of Eu{sup 3+} doped Y{sub 3}NbO{sub 7} niobate induced by temperature.

Effect of ZrB{sub 2} particles on the microstructure and mechanical properties of hybrid (ZrB{sub 2} + Al{sub 3}Zr)/AA5052 insitu composites

Energy Technology Data Exchange (ETDEWEB)

Gautam, Gaurav, E-mail: gauravgautamm1988@gmail.com; Mohan, Anita, E-mail: amohan.app@iitbhu.ac.in

2015-11-15

Present study outlines the effect of ZrB{sub 2} particles variation on the morphology and mechanical properties of (ZrB{sub 2}+Al{sub 3}Zr)/AA5052Al alloy composites. Composites with varying amount of ZrB{sub 2} particles have been produced by direct melt reaction (DMR) technique. These composites have been characterized by X-ray diffractometer (XRD) and energy-dispersive spectroscopy (EDS) to confirm the presence of ZrB{sub 2} and Al{sub 3}Zr particles. Optical microscopy (OM) and scanning-electron microscopy (SEM) have been used to understand the morphology. To see the effect of ZrB{sub 2} variation on mechanical properties, hardness and tensile properties have been evaluated. The XRD and EDS results confirm the successful formation of ZrB{sub 2} particles in matrix of AA5052Al alloy. SEM and TEM studies exhibit that ZrB{sub 2} particles are mostly in hexagonal and some rectangular shape while Al{sub 3}Zr particles are in polyhedron and rectangular shapes. Most of ZrB{sub 2} particles are within a size range of 10–190 nm. Interface region is free of any impurity. OM studies show grain refinement of AA5052Al alloy matrix with formation of second phase ZrB{sub 2} particles. Tensile results indicate that the UTS and YS improve up to 3 vol.% of ZrB{sub 2} but beyond this composition a decreasing trend is observed. The strength coefficient increases with increase in ZrB{sub 2} particles up to 3 vol.% in the Al{sub 3}Zr/Al alloy composites, whereas strain hardening decreases. While beyond 3 vol.% ZrB{sub 2} particles in the Al{sub 3}Zr/Al alloy composite, opposite trend is observed in strength coefficient and strain hardening. Percentage elongation also improves with 1vol.% ZrB{sub 2}, but further addition of ZrB{sub 2} shows an adverse effect. However, a continuous increasing trend has been observed in bulk hardness. Fracture studies show facets of Al{sub 3}Zr particles and dimples of matrix, but with inclusion of ZrB{sub 2} dimple size decreases. Increase in ZrB{sub

Investigations of mussel-inspired polydopamine deposition on WC and Al{sub 2}O{sub 3} particles: The influence of particle size and material

Energy Technology Data Exchange (ETDEWEB)

Mondin, Giovanni, E-mail: giovanni.mondin@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Haft, Marcel, E-mail: m.haft@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Wisser, Florian M., E-mail: florian.wisser@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Leifert, Annika, E-mail: annika.leifert@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Mohamed-Noriega, Nasser, E-mail: nasser.mohamed-noriega@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Dörfler, Susanne, E-mail: susanne.doerfler@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Hampel, Silke, E-mail: s.hampel@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Grothe, Julia, E-mail: stefan.kaskel@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Kaskel, Stefan, E-mail: julia.grothe@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany)

2014-12-15

Polydopamine, formed by oxidation of dopamine, is a bioinspired polymer developed for multifunctional coatings by Lee et al. in 2007 by drawing inspiration from the adhesive proteins found in mussels. Due to their high versatility and substrate-independence, polydopamine coatings are gaining considerable attention in a plethora of research fields, particularly in the coating of particles, but systematic investigations of the polydopamine coating process are lacking in the literature. In this study, we explore by TEM and thermogravimetric analysis the polydopamine coating process on alumina microparticles, tungsten carbide microparticles and tungsten carbide nanoparticles. By choosing two substrates with similar size but different material (Al{sub 2}O{sub 3} and WC), as well as two substrates of the same material but different size (WC micro- and nanoparticles) we investigate the effects of both substrate material and substrate size, in order to gain some insights into the polydopamine particle coating process. As opposed to what is generally assumed in the literature, we found that the polydopamine coating thicknesses on particles, as well as the thickness growing trend, depend on the particles size and material. In particular, after 24 h of polymerization time the polydopamine coatings reached a thickness of 65 ± 10 nm in the case of Al{sub 2}O{sub 3} microparticles, 18 ± 4 nm in the case of WC microparticles and 33 ± 6 nm in the case of WC nanoparticles. - Highlights: • The coating of different particles with polydopamine was systematically investigated. • Al{sub 2}O{sub 3} microparticles and WC microparticles and nanoparticles were investigated. • The thickness of the polydopamine coating depends on the particle size. • The thickness of the polydopamine coating depends on the particle material.

On the thermal stability of ultrafine-grained Al stabilized by in-situ amorphous Al{sub 2}O{sub 3} network

Energy Technology Data Exchange (ETDEWEB)

Balog, Martin, E-mail: martin.balog@savba.sk [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 83102 Bratislava (Slovakia); Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Hu, Tao [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Krizik, Peter [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 83102 Bratislava (Slovakia); Castro Riglos, Maria Victoria [Centro Atómico Bariloche, Av. Bustillo 9.500 (8400) Bariloche, Río Negro (Argentina); Saller, Brandon D.; Yang, Hanry; Schoenung, Julie M.; Lavernia, Enrique J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)

2015-11-11

Bulk Al materials with average grain sizes of 0.47 and 2.4 µm, were fabricated by quasi-isostatic forging consolidation of two types of Al powders with average particle sizes of 1.3 and 8.9 μm, respectively. By utilizing the native amorphous Al{sub 2}O{sub 3} (am-Al{sub 2}O{sub 3}) film on the Al powders surfaces, a continuous, ∼7 nm thick, am-Al{sub 2}O{sub 3} network was formed in situ in the Al specimens. Systematic investigation of the changes to the am-Al{sub 2}O{sub 3} network embedded in the Al matrix upon heating and annealing up to 600 °C was performed by transmission electron microscopy (TEM). At the same time, the stability of the Al grain structure was studied by transmission Kikuchi diffraction (TKD), electron back-scatter diffraction (EBSD), and TEM. The am-Al{sub 2}O{sub 3} network remained stable after annealing at 400 °C for 24 h. In-situ TEM studies revealed that at temperatures ≥450 °C, phase transformation of the am-Al{sub 2}O{sub 3} network to crystalline γ-Al{sub 2}O{sub 3} particles occurred. After annealing at 600 °C for 24 h the transformation was completed, whereby only nanometric γ-Al{sub 2}O{sub 3} particles with an average size of 28 nm resided on the high angle grain boundaries of Al. Due to the pinning effect of γ-Al{sub 2}O{sub 3}, the Al grain and subgrain structures remained unchanged during annealing up to 600 °C for 24 h. The effect of the am-Al{sub 2}O{sub 3}→γ-Al{sub 2}O{sub 3} transformation on the mechanical properties of ultrafine- and fine-grained Al is discussed from the standpoint of the underlying mechanisms.

Experimental Investigation on Cutting Characteristics in Nanometric Plunge-Cutting of BK7 and Fused Silica Glasses.

Science.gov (United States)

An, Qinglong; Ming, Weiwei; Chen, Ming

2015-03-27

Ductile cutting are most widely used in fabricating high-quality optical glass components to achieve crack-free surfaces. For ultra-precision machining of brittle glass materials, critical undeformed chip thickness (CUCT) commonly plays a pivotal role in determining the transition point from ductile cutting to brittle cutting. In this research, cutting characteristics in nanometric cutting of BK7 and fused silica glasses, including machined surface morphology, surface roughness, cutting force and specific cutting energy, were investigated with nanometric plunge-cutting experiments. The same cutting speed of 300 mm/min was used in the experiments with single-crystal diamond tool. CUCT was determined according to the mentioned cutting characteristics. The results revealed that 320 nm was found as the CUCT in BK7 cutting and 50 nm was determined as the size effect of undeformed chip thickness. A high-quality machined surface could be obtained with the undeformed chip thickness between 50 and 320 nm at ductile cutting stage. Moreover, no CUCT was identified in fused silica cutting with the current cutting conditions, and brittle-fracture mechanism was confirmed as the predominant chip-separation mode throughout the nanometric cutting operation.

Lower Saccharide Nanometric Materials and Methods

Energy Technology Data Exchange (ETDEWEB)

Schilling, Christopher H.; Tomasik, Piotr; Sikora, Marek

2004-07-13

A ceramic composition having at least one nanometric ceramic powder, at least one lower saccharide, and water. The composition is useful in many industrial applications, including preparation of stronger and substantially defect free green and sintered ceramic bodies.

Next Generation Qualification: Nanometrics T120PH Seismometer Evaluation

Energy Technology Data Exchange (ETDEWEB)

Merchant, Bion J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Slad, George William [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-10-01

Sandia National Laboratories has tested and evaluated three seismometers, the Trillium 120PH, manufactured by Nanometrics. These seismometers measure broadband ground velocity using a UVW configuration with feedback control in a mechanically levelled borehole package. The purpose of the seismometer evaluation was to determine a measured sensitivity, response, self- noise, dynamic range, and self-calibration ability. The Nanometrics Trillium 120PH seismometers are being evaluated for the U.S. Air Force as part of their Next Generation Qualification effort.

Sol–gel hybrid membranes loaded with meso/macroporous SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} materials with high proton conductivity

Energy Technology Data Exchange (ETDEWEB)

Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Mosa, Jadra, E-mail: jmosa@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Aparicio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi [Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain)

2015-01-15

In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m{sup 2}/g (TiO{sub 2}–P{sub 2}O{sub 5}) and 300 m{sup 2}/g (SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5}). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion{sup ®} at higher temperatures (120 °C) (2·10{sup −2} S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure.

Core–shell structured FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite cores with tunable insulating layer thicknesses

Energy Technology Data Exchange (ETDEWEB)

Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang, E-mail: ligq-wust@mail.wust.edu.cn [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

2015-11-15

Graphical abstract: - Highlights: • FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores were prepared. • SiO{sub 2} surrounding FeSiAl were replaced by Al{sub 2}O{sub 3} during sintering process. • Fe{sub 3}Si particles were separated by Al{sub 2}O{sub 3} with tunable thickness in composite cores. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than FeSiAl core. • The insulating layer between ferromagnetic particles can reduce core loss. - Abstract: FeSiAl/SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses have been synthesized via a modified Stöber method combined with following high temperature sintering process. Most of the conductive FeSiAl particles could be coated by insulating SiO{sub 2} using the modified Stöber method. During the sintering process, the reaction 4Al + 3SiO{sub 2} ≣ 2α-Al{sub 2}O{sub 3} + 3Si took place and the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher resistivity and lower core loss than the raw FeSiAl core. Based on this, several types of FeSiAl/SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores with tunable insulating layer thicknesses were selectively prepared by simply varying TEOS contents. The thickness of Al{sub 2}O{sub 3} insulating layer and resistivity of Fe{sub 3}Si/Al{sub 2}O{sub 3} composite cores increased with increasing the TEOS contents, while the permeability and core loss changed in the opposite direction.

Synthesis of Ce(III)-doped Fe{sub 3}O{sub 4} magnetic particles for efficient removal of antimony from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Qi, Zenglu; Joshi, Tista Prasai [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Ruiping, E-mail: liuruiping@rcees.ac.cn [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Huijuan [University of Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Qu, Jiuhui [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2017-05-05

Highlights: • Doping of Ce into Fe{sub 3}O{sub 4} was achieved based on a facile solvothermal method. • After doping, the removal capacity was increased by 5 times for “Sb(V)” and 2 times for “Sb(III)”. • Decreasing pH improved adsorption of Sb(V) but decreased adsorption of Sb(III). • Antimony sorption mechanisms on Ce-doped Fe{sub 3}O{sub 4} were illustrated. - Abstract: Aqueous antimony (Sb) pollution from human activity is of great concern in drinking water due to its adverse health effect. Magnetic Fe{sub 3}O{sub 4} particles, with high separation ability from solution, have been considered as a low-cost Sb adsorbent for contaminants. However, the limited adsorption capacity has restricted its practical application. In this study, a solvothermal approach was developed for doping Ce(III) into Fe{sub 3}O{sub 4}, thereby increasing the adsorption efficacy for both Sb(III) and Sb(V). In contrast to un-doped Fe{sub 3}O{sub 4}, the adsorption capacity towards Sb(III) and Sb(V) in Ce-doped materials increased from 111.4 to 224.2 mg/g and from 37.2 to 188.1 mg/g at neutral pH, respectively. Based on the combined results of XPS, XRD, and FTIR, it confirmed that Ce atom successfully doped into the Fe{sub 3}O{sub 4} structure, resulting in the decreased particle size, increased the surface area, and isoelectric point. Furthermore, the vibrating sample magnetometer (VSM) results showed that the Ce doping process had some side effects on the primitive magnetic property, but remaining the high separation potential during water treatment. According to the high removal efficiency and magnetic property, the Ce-doped Fe{sub 3}O{sub 4} of great simplicity should be a promising adsorbent for aqueous Sb removal.

Morphological and structural characterization of the Zn{sub 0,9}Mn{sub 0,1}O powder synthesized by combustion reaction and Pechini; Caracterizacao estrutural e morfologica de pos de Zn{sub 0,9}Mn{sub 0,1}O sintetizados por reacao de combustao e metodo Pechini

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, M A; Torquato, R; Simoes, A N; Costa, A C.F.M.; Gama, L [Universidade Federal de Campina Grande (DEMA/UFCG), PB (Brazil). Dept. de Engenharia dos Materiais; Kiminami, R H.G.A. [Universidade Federal de Sao Carlos (DEMA/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

2009-07-01

Zinc oxide, due to the piezoelectric and electro-optical characteristics, is used in application such as, chemical sensor, varistor, transparent conductive thin film and DMS. The aim of this work is to evaluate and compare structural and morphological characteristics of nanometric powders of Zn{sub 0,9}Mn{sub 0,1}O prepared by chemical synthesis of combustion reaction and Pechini method. The powders were characterized by XRD, SEM and BET. The XRD data shown to both studied method the presence of ZnO phase with hexagonal structure and without second phase. The powder prepared by combustion reaction presented 9% of reduction in crystallinity and 42% of increase in surface area in comparison with the powder prepared by Pechini method. The morphological analysis of the powder showed that both method produce powders with soft agglomerates constituted by nano size particles. (author)

Bactericidal effect of blue LED light irradiated TiO{sub 2}/Fe{sub 3}O{sub 4} particles on fish pathogen in seawater

Energy Technology Data Exchange (ETDEWEB)

Cheng, T.C. [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Taiwan (China); Yao, K.S. [Department of Horticulture, National Taitung Junior College, Taiwan (China); Yeh, N. [Mingdao University, Taiwan (China); Chang, C.I. [Aquaculture Division, Fisheries Research Institute, Council of Agriculture, Taiwan (China); Hsu, H.C. [Department of Life Science, Mingdao University, Taiwan (China); Gonzalez, F. [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Taiwan (China); Chang, C.Y., E-mail: cyc1136@yahoo.com.tw [Center of General Education, National Taitung Junior College, Taiwan (China)

2011-05-31

This study uses blue LED light ({lambda}{sub max} = 475 nm) activated TiO{sub 2}/Fe{sub 3}O{sub 4} particles to evaluate the particles' photocatalytic activity efficiency and bactericidal effects in seawater of variable salinities. Different TiO{sub 2} to Fe{sub 3}O{sub 4} mole ratios have been synthesized using sol-gel method. The synthesized particles contain mainly anatase TiO{sub 2}, Fe{sub 3}O{sub 4} and FeTiO{sub 3}. The study has identified TiO{sub 2}/Fe{sub 3}O{sub 4}'s bactericidal effect to marine fish pathogen (Photobacterium damselae subsp. piscicida BCRC17065) in seawater. The SEM photo reveals the surface destruction in bacteria incubated with blue LED irradiated TiO{sub 2}/Fe{sub 3}O{sub 4}. The result of this study indicates that 1) TiO{sub 2}/Fe{sub 3}O{sub 4} acquires photocatalytic activities in both the freshwater and the seawater via blue LED irradiation, 2) higher photocatalytic activities appear in solutions of higher TiO{sub 2}/Fe{sub 3}O{sub 4} mole ratio, and 3) photocatalytic activity decreases as salinity increases. These results suggest that the energy saving blue LED light is a feasible light source to activate TiO{sub 2}/Fe{sub 3}O{sub 4} photocatalytic activities in both freshwater and seawater.

Amperometric glucose sensor based on the Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode obtained from a thin Ni{sub 3}Al foil

Energy Technology Data Exchange (ETDEWEB)

Jarosz, Magdalena, E-mail: jarosz@chemia.uj.edu.pl [Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30060 Krakow (Poland); Socha, Robert P. [Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30239 Krakow (Poland); Jóźwik, Paweł [Faculty of Advanced Technology and Chemistry, Military University of Technology, Kaliskiego 2, 00908 Warsaw (Poland); Sulka, Grzegorz D. [Department of Physical Chemistry and Electrochemistry, Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30060 Krakow (Poland)

2017-06-30

Highlights: • Chemical etching of Ni{sub 3}Al alloy in an acidic mixture was performed. • Electrochemical activity of samples was achieved by their oxidation in NaOH. • Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode showed electrochemical activity towards glucose. • Synthesized material is characterized by high sensitivity and short response time. - Abstract: In this report, we present a facile and relatively fast method to roughen the surface of Ni{sub 3}Al–based intermetallic foil, and test it as an amperometric non-enzymatic glucose sensor. The alloy samples underwent chemical etching in a H{sub 3}PO{sub 4}:CH{sub 3}COOH (HAc):HNO{sub 3}:H{sub 2}O (24:1:1:7 in volume) solution in order to achieve a high surface area with more electroactive sites. The Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrode was fabricated using potential cycling technique in a highly concentrated alkaline solution. The electrodes were tested electrochemically for oxidation of glucose. We have demonstrated that Ni(OH){sub 2}/Al(OH){sub 4}{sup −} electrodes exhibit high sensitivity towards glucose detection (796 μAmM{sup -1}cm{sup -2}) and short response time (3 s) upon successive addition of glucose. Moreover, as for a non-nanometric material, prepared electrodes show a relatively good linear correlation between current density and glucose concentration (0.025–0.45 mM) and limit of detection (47.6 μM). For more in-depth characterization of presented material, electrodes were examined using scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

Shape and catalytic mechanism of RuO{sub 2} particles at CO oxidation reaction conditions. First-principles based multi-scale modeling

Energy Technology Data Exchange (ETDEWEB)

Reuter, Karsten [TU Muenchen (Germany). Lehrstuhl fuer Theoretische Chemie

2016-11-01

For model catalyst studies on low-index single-crystal surfaces close agreement between detailed measurements and quantitative microkinetic modeling can increasingly be achieved. However, for 'real' catalyst particles, such structure-morphology-activity relationships are only scarcely established. This is prototypically reflected by the situation for RuO{sub 2}, as a most active catalyst for CO oxidation. Here, existing first-principles kinetic modeling is restricted to just one facet, namely the RuO{sub 2}(110) surface, which is not able to fully account for activity data obtained from polycrystalline RuO{sub 2} powder catalysts. The overarching objective of this project was correspondingly to close this gap and demonstrate that similarly close agreement as for individual single-crystal model catalysts can also be achieved for catalyst particles. Specifically, we addressed experiments where an intact RuO{sub 2} bulk structure is conserved, and establish the atomic-scale structure and reactivity of other RuO{sub 2} low-index facets under the gas-phase conditions characteristic for catalytic CO oxidation.

Four different animated sub-particles as the origins of the life and creator of different angular momentums of elementary particles

Science.gov (United States)

Gholibeigian, Hassan; Gholibeigian, Zeinab

2015-04-01

Understanding the internal structure of the proton is crucial challenge for QCD, and one important aspect of this is to understand how the spin of the nucleon is build-up from the angular momentum of its quarks and gluons. In this way, what's the origin of differences between angular momentums of fundamental particles? It may be from their substructures. It seems there are four sub-particles of mater, plant, animal and human in substructure of each fundamental particle (string) as the origins of life and cause of differences between spins of those elementary particles. Material's sub-particle always is on and active. When the environmental conditions became ready for creation of each field of the plant, animal and human, sub-particles of their elementary particles became on and active and then, those elementary particles participated in processes of creation in their own field. God, as the main source of information, has been communicated with their sub-particles and transfers a package (bit) of information and laws (plus standard ethics for human sub-particles) to each of them for process and selection (mutation) of the next step of motion and interaction of their fundamental particles with each other in each Plank's time. This is causality for particles' motion in quantum area.

Preparation and self-sterilizing properties of Ag@TiO{sub 2}–styrene–acrylic complex coatings

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xiang-dong; Chen, Feng; Yang, Jin-tao, E-mail: yangjt@zjut.edu.cn; Yan, Xiao-hui; Zhong, Ming-qiang, E-mail: zhongmingqiang@hotmail.com

2013-04-01

In this study, we report a simple and cost-effective method for self-sterilized complex coatings obtained by Ag@TiO{sub 2} particle incorporation into styrene–acrylic latex. The Ag@TiO{sub 2} particles were prepared via a coupling agent modification process. The composite latices characterized by transmission electron microscopy (TEM) study were highly homogeneous at the nanometric scale, and the Ag@TiO{sub 2} particles were well dispersed and exhibited an intimate contact between both the organic and inorganic components. The Ag@TiO{sub 2} nanoparticles significantly enhanced the absorption in the visible region and engendered a good heat-insulating effect of the complex coatings. Moreover, the Ag@TiO{sub 2} nanoparticle incorporation into this polymer matrix renders self-sterilized nanocomposite materials upon light excitation, which are tested against Escherichia coli and Staphylococcus aureus. The complex coatings display an impressive performance in the killing of all micro-organisms with a maximum for a Ag@TiO{sub 2} loading concentration of 2–5 wt.%. The weathering endurance of the complex coating was also measured. - Highlights: ► We prepared Ag@TiO{sub 2}–styrene–acrylic complex latex in one pot. ► Good antibacterial performances of complex coatings were observed. ► The complex coating was resistant to weathering after 48 h. ► The complex coating exhibits good heat-insulating effect.

Influence of defects on sub-Å optical linewidths in Eu{sup 3+}: Y{sub 2}O{sub 3} particles

Energy Technology Data Exchange (ETDEWEB)

Oliveira Lima, Karmel de [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Rocha Gonçalves, Rogéria [Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, CEP 14040-901 Ribeirão Preto, São Paulo, Brasil (Brazil); Giaume, Domitille [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Ferrier, Alban, E-mail: alban.ferrier@chimie-paristech.fr [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Goldner, Philippe, E-mail: philippe.goldner@chimie-paristech.fr [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France)

2015-12-15

Rare earth doped nanocrystals have been recently suggested as useful materials for applications in quantum information processing. To reach optical properties closer to bulk crystals ones, it is still necessary to reduce the defects that can arise in nanoscale structures. Here, we probe the defects level by monitoring the inhomogeneous broadening of the {sup 7}F{sub 0}→{sup 5}D{sub 0} transition in particles of 0.3% at% Eu{sup 3+}:Y{sub 2}O{sub 3}. We find that lines as narrow as 14 GHz (0.015 nm), a value comparable to single crystals, can be obtained in 150 nm particles calcinated at 1200 °C. The additional broadening observed for particles calcinated at lower temperature is attributed to defects inside crystallites and not to surface effects. A linear correlation is also observed between optical and Raman linewidths, suggesting that both processes are sensitive to the same defects. {sup 5}D{sub 0} excited state lifetimes are well described by a model based on an effective refractive index and we conclude that the defects causing the inhomogeneous broadening have no effect on the excited state population.

Layer structured Na{sub 2}Ni(MoO{sub 4}){sub 2} particles as a visible-light-driven photocatalyst for degradation of methylene blue

Energy Technology Data Exchange (ETDEWEB)

Lu, Yuting; Chen, Luyang; Huang, Yanlin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Chen, Cuili; Kim, Sun Il [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-03-15

Highlights: • Na{sub 2}Ni(MoO{sub 4}){sub 2} nanoparticles were developed by Pechini method. • The nanoparticles show high absorption in UV–vis wavelength region. • Na{sub 2}Ni(MoO{sub 4}){sub 2} has high activity in the MB dye degradation under visible light. • Hexagonal layers with heavily distorted NiO{sub 6} were superiority for photocatalysis. - Abstract: A new visible-light-driven photocatalyst of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle was prepared by the modified Pechini method. The crystal structure was measured by X-ray diffraction (XRD) and the structural refinement. The sample was investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectrum measurements. The average size of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle is about 180 nm. Na{sub 2}Ni(MoO{sub 4}){sub 2} particle have an efficient optical absorption in the UV–visible light wavelength region with a direct allowed electronic transition of 2.06 eV. The effective photodegradation of methylene blue (MB) dye was demonstrated, which benefits from the special crystal structure of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle. This crystal lattice has two infinite chains formed by (Ni,Na)O{sub 6} and MoO{sub 4} polyhedra standing in lines alone with the inner wall of the hexagonal tunnels. This results in the efficient optical absorption and provides more chances for electron–hole separations, which can further react with dye molecules to oxidize the dye pollutant into non-toxic products.

Positively charged TiO{sub 2} particles in non-polar system for electrophoretic display

Energy Technology Data Exchange (ETDEWEB)

Chang, Young Seon

2005-02-15

Electrophoretic display uses a technique called electrophoresis to represent images and letters electronically with electronic ink. Although it has good characteristics such as wide viewing angle, high contrast ratio and extremely low power consumption, there are still several issues to be resolved to improve its performances. Higher mobility and stability of the ink particles are the most important issues among them. In this study, TiO{sub 2} particles coated with acrylamide were found to be effective ink particles that satisfy higher mobility and stability. The TiO{sub 2} particles coated with 5∼40% acrylamide were prepared by dispersion polymerization using monomers of methyl methacrylate (MMA) and acrylamide. The TiO{sub 2} particles coated with acrylamide were dispersed in isopar-G with sorbitan esters such as span 20, span 80 and span 85. The size of the TiO{sub 2} particles were changed from 200±150 nm to 350∼500 nm by the coating process. The morphology of coated particles was observed using a transmission electron microscope (TEM) and thermogravimetric analysis (TGA). From the TGA results, the weight fraction of TiO{sub 2} and polymer in coated particle were calculated. From the zeta potential measurement, it was shown that as acrylamide concentration was increased from 5% to 30%, zeta potential of the coated TiO{sub 2} particles was increased from 50mV to about 230mV. The zeta potential of the coated TiO{sub 2} particles with 40% acrylamide was decreased to 50mV. As a stabilizer, span 85 was the most effective surfactant to improve stability of the TiO{sub 2} particles coated with acrylamide among used surfactants in this study. Span 85 showed best stability in the storage test with TiO{sub 2} particles coated with 10% acrylamide. The mobility of TiO{sub 2} particles coated with acrylamide with span 85 in dye solution (Oil Blue-N dissolved in isopar-G) were measured by ITO cell test. The mobility of TiO{sub 2} particles coated with 10∼30

Controllable synthesis of magnetic Fe{sub 3}O{sub 4} particles with different morphology by one-step hydrothermal route

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhongtao; Du, Yi, E-mail: duyi1964@126.com; Li, Zhongfu; Yang, Kai; Lv, Xingjie

2017-03-15

Well-defined Fe{sub 3}O{sub 4} particles were successfully fabricated by a facile triethanolamine (TEA)-assisted method under mild hydrothermal conditions. Hydrated ferric salt was employed as the single iron precursor. TEA was used as the complexing agent and/or alkaline source. The crystalline phases of the as-obtained samples were characterized by X-ray diffraction (XRD). Furthermore, the morphology as well as the compositions of the samples were investigated by scanning electron microscopy (SEM) equipped with an energy dispersion spectroscopy (EDS). The results indicated that the products were Fe{sub 3}O{sub 4} crystal phase, and the morphology and powder size of the particles were varied with adding different amount of NaOAc and keeping the content of TEA unchanged. On the basis of these results, the possible formation mechanism of Fe{sub 3}O{sub 4} was discussed. It was observed that TEA and NaOAc affected the growth rate of crystal planes and nucleation. Besides, the magnetic property tested by a vibrating sample magnetometer (VSM) showed that the products exhibited a ferromagnetic behavior and possessed the excellent saturation magnetization (Ms) at room temperature. - Highlights: • Fe{sub 3}O{sub 4} particles were obtained by employing TEA as single alkali source. • Morphology and size of Fe{sub 3}O{sub 4} particles varied by adjusting the TEA/NaOAc ratio. • Magnetic properties of products were influenced by particle size and morphology.

Some sub-structures of many-particle correlation in nuclei

Energy Technology Data Exchange (ETDEWEB)

Chang, C; Chao, W; Li, K

1977-01-01

The coherent structures of two phonons were proposed as the sub-structure ..cap alpha..' of four-particle clusters for the light nuclei. In the same way the sub-structure ..beta../sup +/ of four-hole clusters can also be given. Based on this the sub-structures between particle clusters and hole clusters in /sup 16/O and /sup 18/O were chosen as examples for investigation. It is found that there is a very strong repulsive force between them. Therefore the loose structure between particle cluster and hole cluster is of the lowest energy state. In this way, the deformations of these states were explained from the microscopic structures. Moreover, these structures can coherently strengthen the E2 transition. Further in order to study the particle correlation in the medium nuclei, the L-S coupling coherent structure is extended to the pseudo L-S coupling coherent structure and the expressions are given in the j-j coupling representation. Some preliminary analyses are made for the nuclei around /sup 56/Ni by using these structures.

Spectroscopy of peaks at microwave range for nanostructure SrFe{sub 12}O{sub 19} and NiFe{sub 2}O{sub 4} ferrite particles

Energy Technology Data Exchange (ETDEWEB)

Ariaee, Sina, E-mail: sina.ariaee@tabrizu.ac.ir; Mehdipour, Mostafa, E-mail: Mostafa_mehdipour67@yahoo.com; Moradnia, Mina, E-mail: mina.moradnia86@gmail.com

2017-05-01

In this paper, (SrFe{sub 12}O{sub 19} and NiFe{sub 2}O{sub 4}) nanostructure ferrite particles were synthesized via the co-precipitation of chloride salts utilizing the sodium hydroxide solution. The resulting precursors were heat-treated at 1100 °C for 4 h. After cooling in the furnace, the ferrite powders were pressed at 0.1 MPa and then sintered at 1200 °C for 4 h. The spectroscopy and characterization of peaks at the microwave range (X-band) for the nanostructure ferrite particles were investigated by the ferromagnetic resonance/transmit-line theories and Reflection Loss (RL) plots. The extracted data from these theoretical and experimental results showed that the natural ferromagnetic resonance can be lead to the narrow peaks and the width of the peaks can be related to the periodic effects. Two kinds of peaks were seen for NiFe{sub 2}O{sub 4} at X-band (8–12 GHz); the narrow peak at (9.8 GHz) was remaining unchanged and consistent while the wide one was shifted from 11 GHz to 8.5 GHz by decreasing the thickness of the samples. These phenomena were also happened for SrFe{sub 12}O{sub 19} samples. The natural resonance was not happened due to the hard magnetic properties of these nano structure particles. - Highlights: • SrFe{sub 12}O{sub 19} and NiFe{sub 2}O{sub 4} nanostructure ferrite particles were synthesized via the co-precipitation of chloride salts. • Two kinds of peaks were seen for NiFe{sub 2}O{sub 4} at X-band (8–12 GHz); these phenomena were also happened for SrFe{sub 12}O{sub 19} samples. • The narrow peaks were remained unchanged and consistent while the wide ones were shifted by decreasing the thickness of the samples. • Characterization procedure was conducted utilizing the ferromagnetic resonance/transmit-line theories and Reflection Loss (RL) plots. • It was concluded that the natural ferromagnetic resonance can be lead to the narrow peaks while the wide ones can be related to the periodic effects.

ZnO/TiO{sub 2} particles and their solar cell application

Energy Technology Data Exchange (ETDEWEB)

Kerli, S., E-mail: suleymankerli@ksu.edu.tr [Department of EnergySystemsEngineering, Faculty of Elbistan Technology, Kahramanmaras SutcuImamUniversity, Kahramanmaras (Turkey); Akgül, Ö., E-mail: omeraakgul@gmail.com [Kahramanmaras Sutcu Imam University, Dept. of Physics, 46100 K.Maras-Turkey (Turkey); Alver, Ü., E-mail: ualver@ktu.edu.tr [Karadeniz Technical University, Dept. of Metallurgical and Materials Eng. 61080, Trabzon-Turkey (Turkey)

2016-03-25

ZnO/TiO{sub 2} particles were investigated for dye-sensitized solar cells (DSSC). Nano-structured ZnO particles were produced by the hydrothermal method. TiO{sub 2} (P25) nanoparticles, was bought from the company of Degussa. Crystal structures and morphological properties of particles were examined by XRD and SEM. As an application, dye sensitized solar cells were fabricated from nano-structured produced metal oxide particles. The working electrodes of the DSSCs were obtained by mixture of ZnO and TiO{sub 2} powders. I-V characteristics of the cells were measured by using a solar simulator and the efficiency of the solar cells were obtained by using I-V graphs. ZnO cells sensitized with Ruthenium 535-bisTBA (N719) dyes yield higher efficiencies than corresponding TiO{sub 2} cells. By increasing TiO{sub 2} amount in the mixture of ZnO/TiO{sub 2}, it was observed that efficiencies of cells are getting lower.

Particle size effect on magnetic and transport properties of La/sub 0.7/Ca/sub 0.3/MnO/sub 3/ nanoparticles

International Nuclear Information System (INIS)

Qaseem, S.; Mumtaz, A.; Hasanain, S.K.; Maaz, K.

2010-01-01

La/sub 0.7/Ca/sub 0.3/MnO/sub 3/ nanoparticles have been synthesized by modified citrate route with particle sizes of 20, 26 and 32 +- 3 nm respectively. The structural characterization has been performed by XRD and TEM analyses while magnetic characterization has been performed by vibrating sample magnetometer (VSM). This work presents the study of size effects on magnetic and electrical properties of Ca-doped CMR nanoparticles (La/sub 0.7/Ca/sub 0.3.MnO/sub 3/). Different particle sizes have been prepared by a wet chemical route. Magnetic characterization reveals that magnetization increases with the increase in the particle size and the magnetic transition temperature for larger particles is the same as in the bulk (258K). The ferromagnetic and resistive transitions are however broad compared to the case of bulk presumably due to the role of the surface. The metal-insulator transition temperature is found to be at 158K while the resistivity shows anomalous low temperature behavior with an upturn at low temperatures presu due to coulomb blockade effects. Furthermore, the field dependence of the resistivity displays nonmonotonic behavior and is explained in terms of the field assisted tunneling between grains. (author)

Effect of synthesis conditions on the nanopowder properties of Ce{sub 0.9}Zr{sub 0.1}O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zimicz, M.G.; Fabregas, I.O.; Lamas, D.G. [CINSO (Centro de Investigaciones en Solidos) CONICET-CITEFA J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Larrondo, S.A., E-mail: susana@di.fcen.uba.ar [Laboratorio de Procesos Cataliticos, Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Pabellon de Industrias, Ciudad Universitaria, 1428 Buenos Aires (Argentina)

2011-06-15

Graphical abstract: . The synthesis of nanocrystalline Ce{sub 0.9}Zr{sub 0.1}O{sub 2} powders via the gel-combustion method, using different fuels, and following either stoichiometric or non-stoichiometric pH-controlled routes is investigated. Research highlights: {yields} All samples exhibited the fluorite-type crystal structure, nanometric average crystallite size and negligible carbon content. {yields} Synthesis conditions strongly affect the average crystallite size, the degree of agglomeration, the specific surface area and the pore volume. {yields} Our results indicate that, by controlling the synthesis conditions it is possible to obtain solids with custom-made morphological properties. -- Abstract: In this work, the synthesis of nanocrystalline Ce{sub 0.9}Zr{sub 0.1}O{sub 2} powders via the gel-combustion method, using different fuels, and following either stoichiometric or non-stoichiometric pH-controlled routes is investigated. The objective is to evaluate the effect of synthesis conditions on the textural and morphological properties, and the crystal structure of the synthesized materials. The solids were characterized by nitrogen physisorption, Scanning Electron Microscopy (SEM), X-ray powder diffraction (XPD), and Carbon-Hydrogen-Nitrogen Elemental Analysis (CHN). All the powders exhibited nanometric crystallite size, fluorite-type structure and negligible carbon content. Synthesis conditions strongly affect the average crystallite size, the degree of agglomeration, the specific surface area and the pore volume. Our results indicate that, by controlling the synthesis conditions it is possible to obtain solids with custom-made morphological properties.

Production and characterization of submicron hematite (α−Fe{sub 2}O{sub 3}) particles by ultrasonic spray pyrolysis method

Energy Technology Data Exchange (ETDEWEB)

Kırcı, Burak; Ebin, Burçak; Gürmen, Sebahattin [Department of Metallurgical and Materials Engineering, Istanbul Technical University Istanbul (Turkey)

2013-12-16

The ultrasonic spray pyrolysis (USP) method has been used to prepare submicron hematite (α−Fe{sub 2}O{sub 3}) particles using two different industrial pickling solutions of iron chloride (41 g/L FeCl{sub 2} and 54 g/L FeCl{sub 3}) Particles were obtained by thermal decomposition of generated aerosols from precursor solutions using 1.7 MHz ultrasonic atomizer. Reaction temperature was set up at 800 °C and aerosol droplets were carried into the heated zone by 0.7 L/min air flow rate. X-Ray Diffraction (XRD) studies were used to determine the crystal structure and crystallite size of the particles. Results indicate that patterns correspond to hematite phase with rhombohedral crystal structure (space group: R3c). The crystallite sizes of particles prepared from FeCl{sub 2} and FeCl{sub 3} solutions that were calculated from Scherrer equation are 59 and 33 nm, respectively. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) investigations give detailed information about particle size, morphology and composition. SEM micrographs show that hematite nanoparticles aggregate and formed spherical secondary particles in submicron range.

Effect of ball milling and dynamic compaction on magnetic properties of Al{sub 2}O{sub 3}/Co(P) composite particles

Energy Technology Data Exchange (ETDEWEB)

Denisova, E. A. [Kirensky Institute of Physics SB RAS, Krasnoyarsk (Russian Federation); Krasnoyarsk Institute of Railways Transport, Krasnoyarsk (Russian Federation); Kuzovnikova, L. A. [Krasnoyarsk Institute of Railways Transport, Krasnoyarsk (Russian Federation); Iskhakov, R. S., E-mail: rauf@iph.krasn.ru; Eremin, E. V. [Kirensky Institute of Physics SB RAS, Krasnoyarsk (Russian Federation); Bukaemskiy, A. A. [Institut fur Sicherheitsforschung und Reaktortechnik, D-52425 Juelich (Germany); Nemtsev, I. V. [Krasnoyarsk Scientific Center SB RAS, Krasnoyarsk (Russian Federation)

2014-05-07

The evolution of the magnetic properties of composite Al{sub 2}O{sub 3}/Co(P) particles during ball milling and dynamic compaction is investigated. To prepare starting composite particles, the Al{sub 2}O{sub 3} granules were coated with a Co{sub 95}P{sub 5} shell by electroless plating. The magnetic and structural properties of the composite particles are characterized by scanning electron microscopy, X-ray diffraction, and the use of the Physical Property Measurement System. The use of composite core-shell particles as starting powder for mechanoactivation allows to decrease treatment duration to 1 h and to produce a more homogeneous bulk sample than in the case of the mixture of Co and Al{sub 2}O{sub 3} powders. The magnetic properties of the milled composite particles are correlated with changes in the microstructure. Reduction in grain size of Co during milling leads to an increase of the volume fraction of superparamagnetic particles and to a decrease of the saturation magnetization. The local magnetic anisotropy field depends on the amount of hcp-Co phase in sample. The anisotropy field value decreases from 8.4 kOe to 3.8 kOe with an increase in milling duration up to 75 min. The regimes of dynamic compaction were selected so that the magnetic characteristics—saturation magnetization and coercive field—remained unchanged.

Particle size distribution of UO sub 2 aerosols

Energy Technology Data Exchange (ETDEWEB)

Raghunath, B. (Radiation Safety Systems Div., BARC, Bombay (India)); Ramachandran, R.; Majumdar, S. (Radiometallurgy Div., BARC, Bombay (India))

1991-12-01

The Anderson cascade impactor has been used to determine the activity mean aerodynamic diameter and the particle size distribution of UO{sub 2} powders dispersed in the form of stable aerosols in an air medium. The UO{sub 2} powders obtained by the calcination of ammonium uranyl carbonate (AUC) and ammonium diuranate (ADU) precipitates have been used. (orig./MM).

Effects of calcination temperature on phase formation and particle size of Zn{sub 2}Nb{sub 34}O{sub 87} powder synthesized by solid-state reaction

Energy Technology Data Exchange (ETDEWEB)

Amonpattaratkit, Penphitcha, E-mail: p.amonpattaratkit@gmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Ananta, Supon, E-mail: suponananta@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2013-05-15

The solid-state mixed oxide method via a rapid vibro-milling technique was explored for the preparation of single-phase Zn{sub 2}Nb{sub 34}O{sub 87} nanopowders. Phase formation of zinc niobate was investigated as a function of calcination temperature by using a combination of thermogravimetric/differential thermal analyzer (TG/DTA) and X-ray diffraction (XRD) techniques. Morphology, particle size and chemical composition of the powders were determined by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) technique. The obtained results clearly revealed the influences of calcination temperature on phase formation and particle size of Zn{sub 2}Nb{sub 34}O{sub 87} nanopowder. - Highlights: ► Single phase Zn{sub 2}Nb{sub 34}O{sub 87} was firstly prepared by solid-state mixed oxide method via a rapid vibro-milling technique. ► The influences of calcination temperature on phase formation and particle size were investigated. ► Zn{sub 2}Nb{sub 34}O{sub 87} powders were characterized by TG–DTA, XRD, SEM and EDX.

Study on CO{sub 2} absorption enhancement by adding active carbon particles into MEA solution

Energy Technology Data Exchange (ETDEWEB)

Qian, Juan; Sun, Rui; Ma, Lian; Sun, Shaozeng [Harbin Institute of Technology, Harbin (China). School of Energy Science and Engineering

2013-07-01

The chemical absorption of CO{sub 2} is generally recognized as the most efficient post-combustion technology of CO{sub 2} separation at present. A study on CO{sub 2} absorption enhancement by adding small particles of active carbon into MEA solution is investigated within a self-designed glass stirring tank. Experiments of different particle loadings and different particle sizes have been conducted. When active carbon particle concentration is fewer, compared to the absorption rate of CO{sub 2} gas absorbed by MEA aqueous solution, the role of active carbon adsorption CO{sub 2} gas is negligible. The enhancement efficiency of CO{sub 2} absorption could be improved by 10% to the upmost in this liquid-particle system.

Kinetics of gas to particle conversion in the NH/sub 3/-Chl system

Energy Technology Data Exchange (ETDEWEB)

Luria, M; Cohen, B

1980-01-01

Particle formation in the reaction of NH/sub 3/ and Chl under 1 atm of N/sub 2/ and at 25/sup 0/C was studied in a flow reactor. The critical concentration below which NO particle can be formed was found to be 3.5 x 10/sup +14/ molecule/CM/sup 3/ for (NH/sub 3/)=(HCl). Above this concentration, gas-particle conversion percentage increases rapidly to approach 100%.

Crack fronts and damage in glass at the nanometre scale

International Nuclear Information System (INIS)

Marliere, Christian; Prades, Silke; Celarie, Fabrice; Dalmas, Davy; Bonamy, Daniel; Guillot, Claude; Bouchaud, Elisabeth

2003-01-01

We have studied the low-speed fracture regime for different glassy materials with variable but controlled length scales of heterogeneity in a carefully controlled surrounding atmosphere. By using optical and atomic force microscopy techniques, we tracked, in real-time, the crack tip propagation at the nanometre scale over a wide velocity range (10 -3 -10 -12 m s -1 and below). The influence of the heterogeneities on this velocity is presented and discussed. Our experiments reveal also - for the first time - that the crack progresses through nucleation, growth and coalescence of nanometric damage cavities within the amorphous phase. This may explain the large fluctuations observed in the crack tip velocities for the smallest values. This behaviour is very similar to that involved, at the micrometric scale, in ductile fracture. The only difference is very probably due to the related length scales (nanometric instead of micrometric). The consequences of such a nano-ductile fracture mode observed at a temperature far below the glass transition temperature, T g , in glass is also discussed

XPS, TEM and SAD investigations of nanosized Co{sub x}B{sub y}H{sub z} particles obtained by two different borohydride methods

Energy Technology Data Exchange (ETDEWEB)

Krastev, V. [Bulgarian Acad. of Sci., Sofia (Bulgaria). Inst. of General and Inorg. Chem.; Stoycheva, M. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Lefterova, E. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Dragieva, I. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria); Stoynov, Z. [Central Laboratory of Electrochemical Power Sources, Bulgarian Academy of Sciences, Sofia 1113 (Bulgaria)

1996-07-01

The nanosized Co{sub x}B{sub y}H{sub z} particles synthesised by the ``tea`` and ``antigravity`` methods using a borohydride reduction process have been subjected to structure and composition studies by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and selected area diffraction (SAD). The amounts of the elements Co, B, O{sub 2}, H{sub 2} and C as mean volume values, and surface values for the as-prepared particles, as well as after Ar{sup +} etching to a depth of about 15 nm and 30 nm from the initial particle surface, are determined. About 1.5 atoms of cobalt per atom of boron correspond to samples obtained by the ``antigravity`` method. The binding energy (BE) of 1s electrons of boron atoms has only one value. These particles are angular and are in the typical nanocrystalline state. In the case of samples prepared by the ``tea`` method, two atoms of cobalt per atom of boron are found. The presence of two kinds of BE (B{sup I} and B{sup II}) of 1s electrons of boron atoms in the particles obtained by the ``tea`` method is observed and almost equal amounts of these two states are established in the spectrum. The particles` shape and structure are typical of the amorphous state. The fact that there is one peak when the ``antigravity`` method is applied, in contrast to the two peaks with the ``tea`` method indicates the presence of a metal amorphous state in the latter case. (orig.)

Fabrication of BaTiO{sub 3}/Ni composite particles and their electro-magneto responsive properties

Energy Technology Data Exchange (ETDEWEB)

Lu, Yaping [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Gao, Lingxiang, E-mail: gaolx@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Wang, Lijuan [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Xie, Zunyuan, E-mail: zyxie123@snnu.edu.cn [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China); Gao, Meixiang [Yulin Vocational and Technical College, Yulin 719000 (China); Zhang, Weiqiang [Key Laboratory of Applied Surface and Colloid Chemistry (Shaanxi Normal University), Ministry of Education, Xi’an 710119 (China); School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an 710119 (China)

2017-07-15

Graphical abstract: The spherical BaTiO{sub 3}/Ni particles with excellent structure were made by one-step method through fixing the metal Ni(0) reduced by a specific reducing agent (N{sub 2}H{sub 4}·H{sub 2}O) on the surface of the BaTiO{sub 3} particles with grain diameter of ∼500 nm. BaTiO{sub 3}/Ni particle has double responses of electric and magnetic field simultaneously. Consequentially, coating magnetic metal on BT particle is proposed an effective method to prepare novel electro-magneto responsive particles and one basis of electro-magneto responsive elastomers. - Highlights: • The BaTiO{sub 3}/Ni composite particles were fabricated. • The content of Ni(0) in nickel sheath is 70.2%. • The BaTiO{sub 3}/Ni particles have double responses of electric and magnetic field. - Abstract: BaTiO{sub 3} (BT)/Ni composite particles were made by one-step method through agglomerating the metal Ni(0) nanoparticles reduced by a specific reducing agent (N{sub 2}H{sub 4}·H{sub 2}O) on the surface of BT sphere with diameter of ∼500 nm. The BT/Ni composite particles were characterized by the means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). In BT/Ni particles, pure BT spherical particle was coated with Ni nanoparticles agglomerated on its surface. The average thickness of the Ni sheath was ∼30 nm and the content of Ni(0) and Ni (II) in the sheath were 70.2% and 29.8%, respectively. The responsive effects of BT/Ni particles filled in hydrogel elastomer were investigated by the viscoelastic properties. The results indicate that the BT/Ni particles exhibit electro and magneto coordinated responsive properties (E = 1 kV/mm, H = 0.1 T/mm), which is superior to BT particles with individual electro response.

Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis

DEFF Research Database (Denmark)

Antfolk, M.; Muller, Peter Barkholt; Augustsson, P.

2014-01-01

Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis-based microfl......Handling of sub-micrometer bioparticles such as bacteria are becoming increasingly important in the biomedical field and in environmental and food analysis. As a result, there is an increased need for less labor-intensive and time-consuming handling methods. Here, an acoustophoresis......-based microfluidic chip that uses ultrasound to focus sub-micrometer particles and bacteria, is presented. The ability to focus sub-micrometer bioparticles in a standing one-dimensional acoustic wave is generally limited by the acoustic-streaming-induced drag force, which becomes increasingly significant the smaller...... particles as small as 0.5 μm in diameter in microchannels of square or rectangular cross sections, is demonstrated. Numerical analysis was used to determine generic transverse particle trajectories in the channels, which revealed spiral-shaped trajectories of the sub-micrometer particles towards the center...

Study of uranium oxide milling in order to obtain nanostructured UC{sub x} target

Energy Technology Data Exchange (ETDEWEB)

Guillot, Julien, E-mail: guillotjulien@ipno.in2p3.fr [Institut de Physique Nucléaire CNRS/IN2P3 UMR 8608 – Université Paris Sud, F-91406 ORSAY Cedex (France); Tusseau-Nenez, Sandrine; Roussière, Brigitte; Barré-Boscher, Nicole [Institut de Physique Nucléaire CNRS/IN2P3 UMR 8608 – Université Paris Sud, F-91406 ORSAY Cedex (France); Brisset, François [ICMMO UMR 8182 CNRS – Université Paris Sud, F-91405 Orsay Cedex (France); Mhamed, Maher Cheikh; Lau, Christophe [Institut de Physique Nucléaire CNRS/IN2P3 UMR 8608 – Université Paris Sud, F-91406 ORSAY Cedex (France); Nowak, Sophie [ITODYS, Université Paris Diderot, Sorbonne Paris Cité, CNRS UMR-7086, F-75013 Paris (France); IPSL CNRS UMR 7583 Universités Paris Est Créteil et Paris Diderot, F-94010 Créteil Cedex (France)

2016-05-01

A R&D program is developed at the ALTO facility to provide new beams of exotic neutron-rich nuclei, as intense as possible. In the framework of European projects, it has been shown that the use of refractory targets with nanometric structure allows us to obtain beams of nuclei unreachable until now. The first parameter to be controlled in the processing to obtain targets with a homogeneous nanostructure is the grinding of uranium dioxide, down to 100 nm grain size. In this study, dry and wet grinding routes are studied and the powders are analyzed in terms of phase stabilization, specific surface area and grain morphology. It appears that the grinding, as well dry as wet, leads to the decrease of the particle size. The oxidation of UO{sub 2} is observed whatever the grinding. However, the dry grinding is the most efficient and leads to the oxidation of UO{sub 2} into U{sub 4}O{sub 9} and U{sub 3}O{sub 7} whose quantities increase with the grinding time while crystallite sizes decrease.

Crystal Orientation Effect on the Subsurface Deformation of Monocrystalline Germanium in Nanometric Cutting.

Science.gov (United States)

Lai, Min; Zhang, Xiaodong; Fang, Fengzhou

2017-12-01

Molecular dynamics simulations of nanometric cutting on monocrystalline germanium are conducted to investigate the subsurface deformation during and after nanometric cutting. The continuous random network model of amorphous germanium is established by molecular dynamics simulation, and its characteristic parameters are extracted to compare with those of the machined deformed layer. The coordination number distribution and radial distribution function (RDF) show that the machined surface presents the similar amorphous state. The anisotropic subsurface deformation is studied by nanometric cutting on the (010), (101), and (111) crystal planes of germanium, respectively. The deformed structures are prone to extend along the 110 slip system, which leads to the difference in the shape and thickness of the deformed layer on various directions and crystal planes. On machined surface, the greater thickness of subsurface deformed layer induces the greater surface recovery height. In order to get the critical thickness limit of deformed layer on machined surface of germanium, the optimized cutting direction on each crystal plane is suggested according to the relevance of the nanometric cutting to the nanoindentation.

Lattice strain estimation for CoAl{sub 2}O{sub 4} nano particles using Williamson-Hall analysis

Energy Technology Data Exchange (ETDEWEB)

Aly, Kamal A., E-mail: kamalaly2001@gmail.com [Physics Department, Faculty of Science & Arts, Khulais, University of Jeddah, Jiddah (Saudi Arabia); Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut (Egypt); Khalil, N.M. [Chemistry Department, Faculty of Science & Arts, Khulais, University of Jeddah, Jiddah (Saudi Arabia); Refractories, Ceramics and Building Materials Department, National Research Centre, 12311 Cairo (Egypt); Algamal, Yousif [Chemistry Department, Faculty of Science & Arts, Khulais, University of Jeddah, Jiddah (Saudi Arabia); Saleem, Qaid M.A. [Chemistry Department, Faculty of Science & Arts, Khulais, University of Jeddah, Jiddah (Saudi Arabia); Chemistry Department, Faculty of Education, Aden University, Sabwa (Yemen)

2016-08-15

CoAl{sub 2}O{sub 4} nanoparticles were prepared via coprecipitation technique through mixing 1:1 M ratio of cobalt nitrate and aluminium nitrate solutions at pH 10. CoAl{sub 2}O{sub 4} crystalline phase was confirmed by X-ray diffraction. Scanning electron microscopy (SEM) result reveals that the particles of CoAl{sub 2}O{sub 4} fired at 900 °C were relatively small (21 nm) and uniform. Increased temperature to 1200 °C gives rise to blocky particles and changes in the powders shape, that because of agglomeration came from the calcination of CoAl{sub 2}O{sub 4}. Furthermore, the particle size increase with increasing the calcinated temperature. The crystalline sizes were evaluated by using X-ray peak broadening analysis suggested by Williamson-Hall (W-H) analysis. It was successfully applied for lattice strain and to calculate mechanical stress and energy density values using different three models namely uniform deformation model (UDM), uniform deformation stress model (UDSM) and uniform deformation energy density model (UDEDM). Also, the root mean square strain was determined. These models gave a different strain values which suggested an isotropic nature of the nanoparticles. Besides, the obtained results W-H analysis are in good agreement with that deduced from SEM analysis and Scherrer's formula. - Highlights: • CoAl{sub 2}O{sub 4} nanoparticles were prepared via coprecipitation technique. • CoAl{sub 2}O{sub 4} nanoparticles were characterized by SEM and XRD. • the lattice size and strain were investigated according to W-H analysis. • The latic size were investigated by W-H analysis, SEM and Sherrar's method. • The root mean square strain was determined.

The effect of sintering time on synthesis of in situ submicron {alpha}-Al{sub 2}O{sub 3} particles by the exothermic reactions of CuO particles in molten pure Al

Energy Technology Data Exchange (ETDEWEB)

Dikici, Burak, E-mail: burakdikici@yyu.edu.tr [Yuzuncu Yil University, Department of Mechanical Engineering, 65080 Van (Turkey); Gavgali, Mehmet [Ataturk University, Department of Mechanical Engineering, 25240 Erzurum (Turkey)

2013-02-25

Highlights: Black-Right-Pointing-Pointer Al-Cu/Al{sub 2}O{sub 3} composites were prepared successfully by means of hot pressing method. Black-Right-Pointing-Pointer Sintering time of the Al-CuO system effect the reaction rate and formation of Al{sub 2}O{sub 3}. Black-Right-Pointing-Pointer Increase in sintering time accelerates formation of submicron in situ {alpha}-Al{sub 2}O{sub 3} phase. Black-Right-Pointing-Pointer Hardness of the sintered composite for 30 min at 1000 Degree-Sign C increased from 60 to 174 HV. - Abstract: In this study, in situ {alpha}-Al{sub 2}O{sub 3} reinforcing particles have been successfully synthesised in an Al-Cu matrix alloy by means of the conventional Hot Pressing (HP) method. The effect of sintering time on the forming of the {alpha}-Al{sub 2}O{sub 3} phase at 1000 Degree-Sign C was investigated using Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and a Scanning Electron Microscope (SEM). The sintered composites contained thermodynamically stable {alpha}-Al{sub 2}O{sub 3} particles and {theta}-Al{sub 2}Cu eutectic phases, which were embedded in the Al-Cu matrix. The in situ {alpha}-Al{sub 2}O{sub 3} particles were generally spherical and their mean size was observed to be less than 0.5 {mu}m. The results showed that sintering time influences not only the reaction rate of copper and the formation of Al{sub 2}O{sub 3}. Also, an increase in the sintering time accelerates the formation of submicron in situ {alpha}-Al{sub 2}O{sub 3} particles and decreases the quantity of {theta}-Al{sub 2}Cu intermetallic phase in the liquid aluminium. Additionally, sintering of composite for 30 min at 1000 Degree-Sign C increased the hardness from 60 to 174 HV.

Particle morphology and magnetic properties of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} powder calcined conventionally and by microwave heating

Energy Technology Data Exchange (ETDEWEB)

Kanagesan, S., E-mail: kanagu1980@gmail.com [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Hashim, M. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Jesurani, S. [Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625601, Tamil Nadu (India); Kalaivani, T. [Center for material science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Ismail, I.; Shafie, M.S.E. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia)

2012-12-05

Highlights: Black-Right-Pointing-Pointer Synthesis of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} by sol-gel technique. Black-Right-Pointing-Pointer Crystallization temperature is reduced to 900 Degree-Sign C due to the addition of D-Fructose. Black-Right-Pointing-Pointer Results of conventional and microwave calcined samples are reported. - Abstract: Barium strontium hexaferrite (Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}-BSF) has been prepared by sol-gel process involving use of D-Fructose as a fuel. The prepared precursor was calcined in two different calcinations techniques conventional and microwave furnace. X-ray powder diffraction studies confirmed the formation of single phase Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}. HR-SEM results show the morphology of the particles is hexagonal structures in platelet form. The average particle size of conventionally calcined BSF powder is 100-250 nm and that of microwave calcined powder is 30-100 nm. The broad hysteresis loop reveals that powder is well crystallized and exhibits hard magnetic properties.

Synthesis of (Ga <sub>1–xsub> Zn <sub>x> )(N <sub>1–xsub> O <sub>x> ) with Enhanced Visible-Light Absorption and Reduced Defects by Suppressing Zn Volatilization

Energy Technology Data Exchange (ETDEWEB)

Chen, Dennis P.; Skrabalak, Sara E.

2016-04-18

(Ga<sub>1–xsub>)(N>1–xsub> O <sub>x>) (GZNO) particles with enhanced optical absorption were synthesized by topotactic transformation of Zn²⁺/Ga³⁺ layered double hydroxides. This outcome was achieved by suppressing Zn volatilization during nitridation by maintaining a low partial pressure of O<sub>2sub> (p<sub>O2sub>). Zn-rich (x > 1/3) variants of GZNO were achieved and compared to those prepared by conventional ammonoylsis conditions. The optical absorption and structural properties of these samples were compared to those prepared in the absence of O<sub>2sub> by diffuse-reflectance spectroscopy and powder X-ray diffraction methods. Notably, suppression of Zn volatilization leads to smaller-band-gap materials (2.30 eV for x = 0.42 versus 2.71 eV for x = 0.21) and reduced structural defects. This synthetic route and set of characterizations provide useful structure–property studies of GZNO and potentially other oxynitrides of interest as photocatalysts.

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y{sub 2}O{sub 3} particles

Energy Technology Data Exchange (ETDEWEB)

Genc, Aziz, E-mail: agenc@itu.edu.t [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey); Luetfi Ovecoglu, M. [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey)

2010-10-15

Research highlights: {yields} Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. {yields} Reinforcement of the selected Ni-W powders with WC and Y{sub 2}O{sub 3} particles and further MA together for 12 h. {yields} There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. {yields} Sintering of the developed composites and the characterization investigations of the sintered samples. {yields} Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y{sub 2}O{sub 3} particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 {sup o}C for 1 h under Ar and H{sub 2} gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

Assembly and luminescence properties of lanthanide-polyoxometalates/polyethyleneimine/SiO{sub 2} particles with core–shell structure

Energy Technology Data Exchange (ETDEWEB)

Wang, Jun, E-mail: junwang924@yahoo.com.cn; Fan, Shaohua; Zhao, Weiqian; Zhang, Hongyan

2013-01-01

In this paper, two lanthanide-polyoxometalate (LnW{sub 10}) complexes were bonded on the surface of the polyethyleneimine (PEI)-modified silica nanoparticles with different sizes, resulting in the formation of LnW{sub 10}/PEI/SiO{sub 2} particles. The hybrid core–shell particles were characterized by infrared, luminescent spectra, scanning electronic microscope, and transmission electronic microscope. The particles obtained exhibit the fine spherical core–shell structure and the excellent luminescence properties. The luminescence spectra studies revealed that the formation of LnW{sub 10}/PEI/SiO{sub 2} particles and the size of particle have an influence on the luminescence properties of lanthanide ions. - Highlights: ► SiO{sub 2}/polyethyleneimine (PEI) shows the chemisorption for Ln-polyoxometalates (LnW{sub 10}). ► The core-shell LnW{sub 10}/PEI/SiO{sub 2} nanoparticles with different sizes were fabricated. ► The hybrid particles exhibit the excellent luminescence properties. ► The sizes of particles affect the luminescence properties of lanthanide ions.

Linear nanometric tunnel junction sensors with exchange pinned sensing layer

International Nuclear Information System (INIS)

Leitao, D. C.; Silva, A. V.; Cardoso, S.; Ferreira, R.; Paz, E.; Deepack, F. L.; Freitas, P. P.

2014-01-01

Highly sensitive nanosensors with high spatial resolution provide the necessary features for high accuracy imaging of isolated magnetic nanoparticles. In this work, we report the fabrication and characterization of MgO-barrier magnetic tunnel junction nanosensors, with two exchange-pinned electrodes. The perpendicular magnetization configuration for field sensing is set using a two-step annealing process, where the second annealing temperature was optimized to yield patterned sensors responses with improved linearity. The optimized circular nanosensors show sensitivities up to 0.1%/Oe, larger than previously reported for nanometric sensors and comparable to micrometric spin-valves. Our strategy avoids the use of external permanent biasing or demagnetizing fields (large for smaller structures) to achieve a linear response, enabling the control of the linear operation range using only the stack and thus providing a small footprint device

Linear nanometric tunnel junction sensors with exchange pinned sensing layer

Energy Technology Data Exchange (ETDEWEB)

Leitao, D. C., E-mail: dleitao@inesc-mn.pt; Silva, A. V.; Cardoso, S. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); Instituto Superior Técnico (IST), Universidade de Lisboa, Av. Rovisco Pais, 1000-029 Lisboa (Portugal); Ferreira, R.; Paz, E.; Deepack, F. L. [INL, Av. Mestre Jose Veiga, 4715-31 Braga (Portugal); Freitas, P. P. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisboa (Portugal); INL, Av. Mestre Jose Veiga, 4715-31 Braga (Portugal)

2014-05-07

Highly sensitive nanosensors with high spatial resolution provide the necessary features for high accuracy imaging of isolated magnetic nanoparticles. In this work, we report the fabrication and characterization of MgO-barrier magnetic tunnel junction nanosensors, with two exchange-pinned electrodes. The perpendicular magnetization configuration for field sensing is set using a two-step annealing process, where the second annealing temperature was optimized to yield patterned sensors responses with improved linearity. The optimized circular nanosensors show sensitivities up to 0.1%/Oe, larger than previously reported for nanometric sensors and comparable to micrometric spin-valves. Our strategy avoids the use of external permanent biasing or demagnetizing fields (large for smaller structures) to achieve a linear response, enabling the control of the linear operation range using only the stack and thus providing a small footprint device.

Fabrication and Characterization of Surrogate TRISO Particles Using 800μm ZrO<sub>2sub> Kernels

Energy Technology Data Exchange (ETDEWEB)

Jolly, Brian C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Helmreich, Grant [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cooley, Kevin M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dyer, John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-07-01

In support of fully ceramic microencapsulated (FCM) fuel development, coating development work is ongoing at Oak Ridge National Laboratory (ORNL) to produce tri-structural isotropic (TRISO) coated fuel particles with both UN kernels and surrogate (uranium-free) kernels. The nitride kernels are used to increase fissile density in these SiC-matrix fuel pellets with details described elsewhere. The surrogate TRISO particles are necessary for separate effects testing and for utilization in the consolidation process development. This report focuses on the fabrication and characterization of surrogate TRISO particles which use 800μm in diameter ZrO<sub>2sub> microspheres as the kernel.

Thickness Measurement of V2O5 Nanometric Thin Films Using a Portable XRF

Directory of Open Access Journals (Sweden)

Fabio Lopes

2016-01-01

Full Text Available Nanometric thin films have always been chiefly used for decoration; however they are now being widely used as the basis of high technology. Among the various physical qualities that characterize them, the thickness strongly influences their properties. Thus, a new procedure is hereby proposed and developed for determining the thickness of V2O5 nanometric thin films deposited on the glass surface using Portable X-Ray Fluorescence (PXRF equipment and the attenuation of the radiation intensity Kα of calcium present in the glass. It is shown through the present paper that the radiation intensity of calcium Kα rays is proportional to film thickness in nanometric films of vanadium deposited on the glass surface.

Hygroscopic growth of sub-micrometer and one-micrometer aerosol particles measured during ACE-Asia

Directory of Open Access Journals (Sweden)

A. Massling

2007-06-01

Full Text Available Hygroscopic properties of aerosol particles in the sub-micrometer and one-micrometer size ranges were measured during the ACE-Asia study (Aerosol Characterization Experiment-Asia in spring 2001. The measurements took place off the coasts of Japan, Korea, and China. All instruments contributing to this study were deployed in a container on the forward deck of the NOAA Research Vessel Ronald H. Brown. Air masses with primarily marine influence and air masses from the Asian continent affected by both anthropogenic sources and by the transport of desert dust aerosol were encountered during the cruise.

Results showed very different hygroscopic behavior in the sub-micrometer size range compared to the one-micrometer size range. In general, for all continentally influenced air masses, the one-micrometer particle population was characterized by two different particle groups – a nearly hydrophobic fraction with growth factors around 1.0 representative of dust particles and a sea salt fraction with hygroscopic growth factors around 2.0. The number fraction of dust particles was generally about 60% independent of long-range air mass origin.

For sub-micrometer particles, a dominant, more hygroscopic particle fraction with growth factors between 1.5 and 1.9 (depending on dry particle size consistent with ammonium sulfate or non-neutralized sulfates as major component was always found. In marine air masses and for larger sizes within the sub-micrometer range (Dp=250 and 350 nm, a sea salt fraction with growth factors between 2.0 and 2.1 was also observed. For all other air masses, the more hygroscopic particle fraction in the sub-micrometer size range was mostly accompanied by a less hygroscopic particle fraction with growth factors between 1.20 and 1.55 depending on both the continental sources and the dry particle size. Number fractions of this particle group varied between 4 and 39% depending on dry particle size and air mass

The effect of diameter ratio between transducers and reactor in sonication-assisted synthesis of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Manaf, A., E-mail: azwar@ui.ac.id; Fahmi, Agam Aidil [Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Yustanti, Erlina [Department of Physics, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Department of Metallurgy, Faculty of Engineering, University of Sultan AgengTirtayasa Jl. Jenderal Sudirman KM 03 Cilegon-Banten 65134 (Indonesia)

2016-04-19

This paper describes the particle size characterization of mechanically alloyed Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} prepared with the aid of a high-power ultrasonic destruction. Analytical-grade BaCO{sub 3}, TiO{sub 2} and SrCO{sub 3} with a purity greater than 99 wt.% were used as precursors for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. The mechanically powders were respectively sintered at 1200 °C for 3 hours to form crystalline powders. This work is aimed at studying the effect of diameter ratio between reactor and transducer of a high power sonicator on the Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles formation. The presence of a single phase of the two materials was confirmed by X-Ray Diffraction (XRD). The concentration of the particles in demineralized water was 3.0 g / 100 mL which become the object of 3 hours ultrasonic destruction subjected to the application of transducer in which the ratio between the diameter of the reactor and the transducer (D/d) was fixed at 1.4, 1.6 and 1.8 respectively. It was found that the mean particle size before the ultrasonic destruction was 538 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 480 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. With D/d of 1.8, the mean particle size of the two materials was found to decrease drastically to 38 nm and 24 nm, respectively. These mean particle sizes were respectively comparable with that of the crystallite size of the particles derived using the Whole Powder Pattern Modelling (WPPM) from which the mean crystallite size of 22 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 14 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} were obtained. It is then confirmed single nanocrystallite Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} particles were already achieved. We can conclude that the ultrasonic destruction to mechanically milled crystalline particles would be one

Microstructure and mechanical properties of ZrO{sub 2} particle dispersion strengthened 16MnV steel

Energy Technology Data Exchange (ETDEWEB)

Wang, B.A. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Wang, N. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); CNOOC Research Institute of Oil and Petrochemicals (CRI), Beijing 100000 (China); Yang, Y.J.; Zhong, H. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang, X.Y.; Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

2017-04-24

The dispersion strengthened 16MnV steels with 0.5 wt% and 1.2 wt% ZrO{sub 2} particles were prepared using medium frequency induction melting furnace. The ZrO{sub 2} particles mixed with iron powder were added into the 16MnV steel through cored-wire injection process. Optical metallographic microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to observe and analyze the microstructure, fracture morphology, dislocation configuration and strengthening mechanism of ZrO{sub 2} particle dispersion strengthened 16MnV steel under as-cast, normalizing and quenching states. Results showed that the strength of 16MnV steel under various states increased significantly after the addition of dispersed ZrO{sub 2} particles. Analysis indicates that the dislocation cell formed by high density dislocation around ZrO{sub 2} particles and attractive interaction between those particles are the main strengthening mechanism of dispersion strengthened 16MnV steel. The tensile test results showed that remarkable strengthening effect of ZrO{sub 2} particle on 16MnV steel has been observed. As the addition of 1.2 wt% ZrO{sub 2}, the improvement of strength in ZrO{sub 2}/16MnV is approximately 37.69% for as-casting, 24.2% after normalization and 29.96% after quenching, respectively. The normalized ZrO{sub 2}/16MnV with 1.2 wt% ZrO{sub 2} has the highest strength of 1453 MPa.

Antibacterial performance of nano polypropylene filter media containing nano-TiO{sub 2} and clay particles

Energy Technology Data Exchange (ETDEWEB)

Shafiee, Sara; Zarrebini, Mohammad; Naghashzargar, Elham, E-mail: e.naghashzargar@tx.iut.ac.ir; Semnani, Dariush, E-mail: d-semnani@cc.iut.ac.ir [Isfahan University of Technology, Department of Textile Engineering (Iran, Islamic Republic of)

2015-10-15

Disinfection and elimination of pathogenic microorganisms from liquid can be achieved by filtration process using antibacterial filter media. The advent of nanotechnology has facilitated the introduction of membranes consisting of nano-fiber in filtration operations. The melt electro-spun fibers due to their extremely small diameters are used in the production of this particular filtration medium. In this work, antibacterial polypropylene filter medium containing clay particles and nano-TiO{sub 2} were made using melt electro-spun technology. Antibacterial performance of polypropylene nano-filters was evaluated using E. coli bacteria. Additionally, filtration efficiency of the samples in terms fiber diameter, filter porosity, and fiber distribution using image processing technique was determined. Air permeability and dust aerosol tests were conducted to establish the suitability of the samples as a filter medium. It was concluded that as far as antibacterial property is concerned, nano-fibers filter media containing clay particles are preferential to similar media containing TiO{sub 2} nanoparticles.

Synthesis of magnetic Fe sub 3 O sub 4 particles covered with a modifiable phospholipid coat

CERN Document Server

Cuyper, M D; Lueken, H; Hodenius, M

2003-01-01

This work reports the synthesis of iron oxide cores by coprecipitation of Fe sup 2 sup + and Fe sup 3 sup + ions with NaHCO sub 3 or NH sub 3. Depending on the experimental conditions, particles of two different sizes (13 or 130 nm diameter) were produced. X-ray diffractometry revealed Fe sub 3 O sub 4 (magnetite) to be the main constituent. The smaller particles, which, in contrast to the larger ones, are superparamagnetic, were stabilized with a phospholipid bilayer consisting of a 9:1 molar ratio of dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol, thereby creating so-called magnetoliposomes. In a subsequent step, poly(ethylene glycol)-(PEG-) derivatized dipalmitoylphosphatidylethanolamine was introduced into the lipid envelope by incubating the magnetoliposomes with pre-formed sonicated vesicles containing the PEGylated lipid. The mechanism by which lipid transfer occurred was determined from the kinetic profiles. The relevance of these observations to a wide range of biomedical applicat...

Effect of Fe{sub 2}O{sub 3} in Fe{sub 2}O{sub 3}/AP composite particles on thermal decomposition of AP and on burning rate of the composite propellant

Energy Technology Data Exchange (ETDEWEB)

Ma, Zhenye [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing, 210094 (China); Nanjing University of Technology, Nanjing (China); Li, Fengsheng; Bai, Huaping [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing, 210094 (China)

2006-12-15

A technique of composite processing of Fe{sub 2}O{sub 3} and ammonium perchlorate (AP) was employed in making the propellant. The effects of composite processing of Fe{sub 2}O{sub 3} on catalytic activity, on the thermal decomposition of AP, and on the burning rate of the composite propellant were investigated in this paper. Fe{sub 2}O{sub 3}/AP composite particles were prepared by a novel solvent-nonsolvent method. The results show that AP is successfully coated on the surface of Fe{sub 2}O{sub 3}. Composite processing of Fe{sub 2}O{sub 3} and AP can improve the catalytic activity of Fe{sub 2}O{sub 3}. Fe{sub 2}O{sub 3} exhibits better catalytic effect with increasing Fe{sub 2}O{sub 3} content. The larger interface between Fe{sub 2}O{sub 3} and AP and lower density of composite propellant (with the added Fe{sub 2}O{sub 3}/AP composite particles) are responsible for the enhancement of the catalytic activity of Fe{sub 2}O{sub 3}. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Magnetic relaxation phenomena and inter-particle interactions in nanosized gamma-Fe sub 2 O sub 3 systems

CERN Document Server

Predoi, D; Tronc, E; Nogues, M; Russo, U; Principi, G; Filoti, G

2003-01-01

Samples of gamma-Fe sub 2 O sub 3 nano-particles with a mean size of 4.0(3) nm and with different hydration and surfactant degrees were prepared by sol-gel methods. Morphology and structural data were obtained by transmission electron microscopy and x-ray diffraction, whereas the surface effects and hyperfine interactions were analysed mainly by Moessbauer spectroscopy. The relative number of surface iron positions was found to be proportional to the amount of OH sup - and SO sub 4 sup 2 sup - groups on the particle surface, which in turn is strictly dependent on the preparation conditions. Strong relaxation processes versus temperature were evidenced in the analysed systems. New criteria for the evaluation of the blocking temperature via Moessbauer measurements are proposed. The results are in good agreement with blocking temperatures obtained by magnetic measurements. Moreover, it was shown that the inter-particle magnetic interactions decrease with the number of iron surface states.

Superparamagnetism and spin-glass like state for the MnFe{sub 2}O{sub 4} nano-particles synthesized by the thermal decomposition method

Energy Technology Data Exchange (ETDEWEB)

Gao Ruorui [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Zhang Yue, E-mail: yue-zhang@mail.hust.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Department of Electric Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Yu Wei [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Xiong Rui [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); Shi Jing [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); International Center for Material Physics, Shen Yang 110015 (China)

2012-08-15

MnFe{sub 2}O{sub 4} nano-particles with an average size of about 7 nm were synthesized by the thermal decomposition method. Based on the magnetic hysteresis loops measured at different temperatures the temperature-dependent saturation magnetization (M{sub S}) and coercivity (H{sub C}) are determined. It is shown that above 20 K the temperature-dependence of the M{sub S} and H{sub C} indicates the magnetic behaviors in the single-domain nano-particles, while below 20 K, the change of the M{sub S} and H{sub C} indicates the freezing of the spin-glass like state on the surfaces. By measuring the magnetization-temperature (M-T) curves under the zero-field-cooling (ZFC) and field-cooling procedures at different applied fields, superparamagnetism behavior is also studied. Even though in the ZFC M-T curves peaks can be observed below 160 K, superparamagnetism does not appear until the temperature goes above 300 K, which is related with the strong inter-particle interaction. - Highlights: Black-Right-Pointing-Pointer MnFe{sub 2}O{sub 4} nano-particles with size of 7 nm were prepared. Black-Right-Pointing-Pointer The surface spin-glass like state is frozen below 20 K. Black-Right-Pointing-Pointer The peaks in ZFC magnetization-temperature curves are observed below 160 K. Black-Right-Pointing-Pointer The inter-particle interaction inhibits the superparamagnetism at room temperature.

Corrosion behaviour of nanometre sized cerium oxide and titanium oxide incorporated aluminium in NaCl solution

International Nuclear Information System (INIS)

Ashraf, P. Muhamed; Edwin, Leela

2013-01-01

Highlights: ► Corrosion resistant aluminium incorporated with nano oxides of cerium and titanium. ► 0.2% nano CeO 2 and 0.05% nano TiO 2 showed increased corrosion resistance. ► Nano TiO 2 concentration influenced the optimum performance of the material. ► Comparison of Micro and nano CeO 2 and TiO 2 aluminium showed the latter is best. - Abstract: The study highlights the development of an aluminium matrix composite by incorporating mixture of nanometre sized cerium oxide and titanium oxide in pure aluminium and its corrosion resistance in marine environment. The mixed nanometre sized oxides incorporated aluminium exhibited improved microstructure and excellent corrosion resistance. Corrosion resistance depends on the concentration of nanometre sized titanium oxide. Electrochemical characteristics improved several folds in nanometre sized mixed oxides incorporated aluminium than micrometre sized oxides incorporated aluminium.

Enhanced thermoelectric properties in p-type Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} alloy by combining incorporation and doping using multi-scale CuAlO{sub 2} particles

Energy Technology Data Exchange (ETDEWEB)

Song, Zijun; Liu, Yuan; Zhou, Zhenxing; Lu, Xiaofang; Wang, Lianjun [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); Zhang, Qihao [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Jiang, Wan [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai (China); Institute of Functional Materials, Donghua University, Shanghai (China); School of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen (China); Chen, Lidong [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai (China)

2017-01-15

Multi-scale CuAlO{sub 2} particles are introduced into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix to synergistically optimize the electrical conductivity, Seebeck coefficient, and the lattice thermal conductivity. Cu element originating from fine CuAlO{sub 2} grains diffuses into the Bi{sub 0.4}Sb{sub 1.6}Te{sub 3} matrix and tunes the carrier concentration while the coarse CuAlO{sub 2} particles survive as the second phase within the matrix. The power factor is improved at the whole temperatures range due to the low-energy electron filtering effect on Seebeck coefficient and enhanced electrical transport property by mild Cu doping. Meanwhile, the remaining CuAlO{sub 2} inclusions give rise to more boundaries and newly built interfaces scattering of heat-carrying phonons, resulting in the reduced lattice thermal conductivity. Consequently, the maximum ZT is found to be enhanced by 150% arising from the multi-scale microstructure regulation when the CuAlO{sub 2} content reaches 0.6 vol.%. Not only that, but the ZT curves get flat in the whole temperature range after introducing the multi-scale CuAlO{sub 2} particles, which leads to a remarkable increase in the average ZT. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sources of sub-micrometre particles near a major international airport

Science.gov (United States)

Masiol, Mauro; Harrison, Roy M.; Vu, Tuan V.; Beddows, David C. S.

2017-10-01

The international airport of Heathrow is a major source of nitrogen oxides, but its contribution to the levels of sub-micrometre particles is unknown and is the objective of this study. Two sampling campaigns were carried out during warm and cold seasons at a site close to the airfield (1.2 km). Size spectra were largely dominated by ultrafine particles: nucleation particles ( strategies are applied successfully.

Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

Energy Technology Data Exchange (ETDEWEB)

Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul Gabriel; McKenzie, Bonnie Beth; Bufford, Daniel Charles; Hall, Aaron Christopher.

2014-09-01

The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and

Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes

Energy Technology Data Exchange (ETDEWEB)

Dalmora, Adilson C. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Institute for Environmental Assessment and Water Studies (IDÆA), Spanish National Research Council (CSIC), C/Jordi Girona 18-26, 08034 Barcelona (Spain); Ramos, Claudete G.; Oliveira, Marcos L.S. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Teixeira, Elba C. [Fundação Estadual de Proteção Ambiental Henrique Luis Roessler, Porto Alegre, RS (Brazil); Kautzmann, Rubens M.; Taffarel, Silvio R. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração. Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Brum, Irineu A.S. de [Universidade Federal do Rio Grande do Sul, Escola de Engenharia, Departamento de Metalurgia, Centro de Tecnologia, Av. Bento Gonçalves, 9500. Bairro Agronomia. CEP: 91501-970 Porto Alegre, RS (Brazil); and others

2016-01-01

Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during “stonemeal” soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO{sub 2}, Al{sub 2}O{sub 3}, and Fe{sub 2}O{sub 3,} with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle

Magnetic fluid with high dispersion and heating performance using nano-sized Fe{sub 3}O{sub 4} platelets

Energy Technology Data Exchange (ETDEWEB)

Kishimoto, Mikio, E-mail: kishimoto.mikio.gb@u.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Miyamoto, Ryoichi; Oda, Tatsuya [Department of Surgery, Division of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Yanagihara, Hideto [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Ohkohchi, Nobuhiro [Department of Surgery, Division of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kita, Eiji [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

2016-01-15

Magnetic fluid with high dispersion and heating performance was developed using 30 to 50 nm platelet Fe{sub 3}O{sub 4} particles. This fluid was prepared by mechanical dispersion in ethyl alcohol with a silane coupling agent, bonding with polyethylene glycol (PEG), and removal of aggregates formed by precipitation. The peak diameter of the resulting Fe{sub 3}O{sub 4} particles, measured by dynamic light scattering, was approximately 150 nm. The fluid exhibited a 300 W/g specific loss power (measured at 114 kHz by a 50.9 kA/m magnetic field). Distribution of the Fe{sub 3}O{sub 4} particles in tissues was observed by intravenously administrating the fluid in mice. The Fe{sub 3}O{sub 4} particles passed through the lungs, and were uniformly distributed throughout the liver and spleen. High dispersion and high heating performance were simultaneously achieved in the magnetic fluid using platelet Fe{sub 3}O{sub 4} particles surface modified with PEG. - Highlights: • Magnetic fluid with high dispersion and heating performance using Fe{sub 3}O{sub 4} particles. • Fluid prepared by mechanical dispersion, bonding with polyethylene glycol. • TEM observation and measurements of particle size distribution and specific loss power of fluid. • Observation of distribution of particles in mice tissues intravenously administrated fluid.

Monodisperse and core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho, and Tm) spherical particles: A facile synthesis and luminescent properties

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhenhe, E-mail: xuzh056@163.com [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Feng, Bin [China National Aviation Fuel Group Corporation, Planning and Development Department, Beijing 100088 (China); Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China); Sun, Yaguang, E-mail: yaguangsun@yahoo.com.cn [College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 100142 (China)

2012-12-15

The core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles were realized by coating the Lu{sub 2}O{sub 3}:Ln{sup 3+} phosphors onto the surface of non-aggregated, monodisperse and spherical SiO{sub 2} particles by the Pechini sol-gel method. The as-synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photolumiminescence (PL), and low-voltage cathodoluminescence (CL). The results indicate that the 800 Degree-Sign C annealed sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores, in spherical shape with a narrow size distribution. The as-obtained particles show strong light emission with different colors corresponding to different Ln{sup 3+} ions under ultraviolet-visible light excitation and low-voltage electron beams excitation, which have potential applications in fluorescent lamps and field emission displays. - Graphical Abstract: Representative SEM and TEM images of the core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Eu{sup 3+} particles; CIE chromaticity diagram showing the emission colors for SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+}; Multicolor emissions of SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles. Highlights: Black-Right-Pointing-Pointer The core-shell particles were realized by coating the phosphors onto the surface of SiO{sub 2} particles. Black-Right-Pointing-Pointer The sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores. Black-Right-Pointing-Pointer The particles show different light emission colors corresponding to Ln{sup 3+} ions. Black-Right-Pointing-Pointer They have potential applications in fluorescent lamps and field emission displays.

Parameters affecting the production of Al-Al/sub 2/O/sub 3/ metal matrix particulate composite, (MMPC)

International Nuclear Information System (INIS)

Zaid, A.I.O.; Jaber, F.

2003-01-01

Aluminum-ceramic composites were made by powder metallurgy up to early 80's. Since then several attempts Metal have been made to produce these composites by liquid metallurgy method. Different techniques have been reported to produce these composites by this method and many difficulties have been encountered in wetting the particles by the molten metal due to the difference in densities which caused non uniform distribution of the particles in the matrix resulting in poor mechanical strength. In this paper, the production of aluminum-aluminum oxide (Al-Al/sub 2/O/sub 3/) metal matrix composite by different techniques is investigated. These include injection, centrifugal vortex, compocasting and a newly suggested method, modified vortex technique. The effect of the process parameters are investigated and discussed and the optimum process conditions were determined. It was found that preheating of the alumina powder for one hour at 1050 deg. before introducing it to the aluminum melt is vital to be accepted by the melt. Incorporation of the alumina particles by injecting them below the surface of the melt resulted in better wettability of the particles but no more than 10% volume fraction was achieved. Similarly, in the centrifuged casting technique, the same volume fraction of the Al/sub 2/O/sub 3/ particles was obtained and in both techniques existence of porosity was observed. The vortex technique, when its parameters were optimized resulted in higher volume fraction, as 25% of alumina particles was achieved with better particle distribution than those obtained by the injection and centrifuged casting methods. Comparison among the different techniques is made based on volume fraction, particle distribution, soundness and micro segregation. A new method, based on modifying the vortex technique is given and discussed. The mechanical strength and hardness of Al-Al/sub 2/O/sub 3/ MMPC produced by this method were determined. It was found that an increase of 100% in

Y{sub 2}BaCuO{sub 5} particle distribution in YBa{sub 2}Cu{sub 3}O{sub 7-y} grains of melt growth processed YBCO oxides; Y{sub 2}BaCuO{sub 5}-Partikelverteilung in YBa{sub 2}Cu{sub 3}O{sub 7-y}-Koernern durch das Melt-Growth-Verfahren verarbeiteter YBCO-Oxide

Energy Technology Data Exchange (ETDEWEB)

Kim, Chan-Joong; Park, Soon-Dong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of). Neutron Science Div.; Park, Hai-Woong [Korea Univ. of Technology and Education, Chungnam (Korea, Republic of). College of Energy, Materials and Chemical Engineering

2013-02-01

Y{sub 2}BaCuO{sub 5} (Y211) particle distribution within YBa{sub 2}Cu{sub 3}O{sub 7-y} (Y123) grains of YBCO samples melt growth (MG) processed was examined. To understand the processing variables on the Y211 distribution, a cooling rate (R{sub C}=1 K/h to R{sub C}=20 K/h) through a peritectic temperature (T{sub p} = 1010 C), a precursor powder size and composition were changed. Two different Y211 distributions (a linear x-like track and planar butterfly-like pattern) were observed, depending on the processing variables. The linear x-like Y211 tracks were observed in the Y123 samples prepared using a stoichiometric Y123 precursor, whereas the planar butterfly-like Y211 patterns were observed in the Y{sub 1.8}Ba{sub 2.4}Cu{sub 3.4}O{sub 7-d} (Y1.8) samples prepared using an Y211-excess composition precursor. The track and planar Y211 patterns were clearer at lower R{sub C} (slower growth rate of Y123 grains) and for the smaller Y211 particles. In contrast, the random Y211 distribution was dominant at the higher R{sub C} and for the larger Y211 particles. The Y211 distribution patterns in the Y123 grains were explained in terms of the interfacial energy difference among growing Y123 fronts. (orig.)

Magnetic properties of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite nanoparticles synthesized by starch-assisted sol–gel autocombustion method and its ball milling

Energy Technology Data Exchange (ETDEWEB)

Yadav, Raghvendra Singh, E-mail: yadav@fch.vutbr.cz [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Havlica, Jaromir [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic); Hnatko, Miroslav; Šajgalík, Pavol [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 36 Bratislava (Slovakia); Alexander, Cigáň [Institute of Measurement Science, Slovak Academy of Sciences, Dúbravská cesta 9, SK-841 04 Bratislava (Slovakia); Palou, Martin; Bartoníčková, Eva; Boháč, Martin; Frajkorová, Františka; Masilko, Jiri; Zmrzlý, Martin; Kalina, Lukas; Hajdúchová, Miroslava; Enev, Vojtěch [Materials Research Centre, Brno University of Technology, Purkyňova 464/118, 61200 Brno (Czech Republic)

2015-03-15

In this article, Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.0 and 0.5) spinel ferrite nanoparticles were achieved at 800 °C by starch-assisted sol–gel autocombustion method. To further reduce the particle size, these synthesized ferrite nanoparticles were ball-milled for 2 h. X-ray diffraction patterns demonstrated single phase formation of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.0 and 0.5) spinel ferrite nanoparticles. FE-SEM analysis indicated the nanosized spherical particles formation with spherical morphology. The change in Raman modes and relative intensity were observed due to ball milling and consequently decrease of particle size and cationic redistribution. An X-ray Photoelectron Spectroscopy (XPS) result indicated that Co{sup 2+}, Zn{sup 2+} and Fe{sup 3+} exist in octahedral and tetrahedral sites. The cationic redistribution of Zn{sup 2+} and consequently Fe{sup 3+} occurred between octahedral and tetrahedral sites after ball-milling. The change in saturation magnetization (M{sub s}) and coercivity (H{sub c}) with decrease of nanocrystalline size and distribution of cations in spinel ferrite were observed. - Highlights: • Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite nanoparticles. • Starch-assisted sol–gel auto-combustion method. • Effect of ball-milling on particle size and cation distribution. • Magnetic property dependent on cations and particle size.

Axion-like particle searches with sub-THz photons

CERN Document Server

Capparelli, L.; Ferretti, J.; Giazotto, F.; Polosa, A.D.; Spagnolo, P.

2016-01-01

We propose a variation, based on very low energy and extremely intense photon sources, on the well established technique of Light-Shining-through-Wall (LSW) experiments for axion-like particle searches. With radiation sources at 30 GHz, we compute that present laboratory exclusion limits on axion-like particles might be improved by at least four orders of magnitude, for masses m_a <~ 0.01~meV. This could motivate research and development programs on dedicated single-photon sub-THz detectors.

Oleate-based hydrothermal preparation of CoFe{sub 2}O{sub 4} nanoparticles, and their magnetic properties with respect to particle size and surface coating

Energy Technology Data Exchange (ETDEWEB)

Repko, Anton, E-mail: anton@a-repko.sk [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 128 43 Prague 2 (Czech Republic); Vejpravová, Jana, E-mail: vejpravo@fzu.cz [Department of Magnetic Nanosystems, Institute of Physics AS CR, v.v.i., Na Slovance 2, 182 21 Prague 8 (Czech Republic); Vacková, Taťana [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Zákutná, Dominika [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 128 43 Prague 2 (Czech Republic); Nižňanský, Daniel, E-mail: daniel.niznansky@natur.cuni.cz [Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 128 43 Prague 2 (Czech Republic)

2015-09-15

We present a facile and high-yield synthesis of cobalt ferrite nanoparticles by hydrothermal hydrolysis of Co–Fe oleate in the presence of pentanol/octanol/toluene and water at 180 or 220 °C. The particle size (6–10 nm) was controlled by the composition of the organic solvent and temperature. Magnetic properties were then investigated with respect to the particle size and surface modification with citric acid or titanium dioxide (leading to hydrophilic particles). The as-prepared hydrophobic nanoparticles (coated by oleic acid) had a minimum inter-particle distance of 2.5 nm. Their apparent blocking temperature (estimated as a maximum of the zero-field-cooled magnetization) was 180 K, 280 K and 330 K for the particles with size of 6, 9 and 10.5 nm, respectively. Replacement of oleic acid on the surface by citric acid decreased inter-particle distance to less than 1 nm, and increased blocking temperature by ca. 10 K. On the other hand, coating with titanium dioxide, supported by nitrilotri(methylphosphonic acid), caused increase of the particle spacing, and lowering of the blocking temperature by ca. 20 K. The CoFe{sub 2}O{sub 4}@TiO{sub 2} nanoparticles were sufficiently stable in water, methanol and ethanol. The particles were also investigated by Mössbauer spectroscopy and alternating-current (AC) susceptibility measurements, and their analysis with Vögel–Fulcher and power law. Effect of different particle coating and dipolar interactions on the magnetic properties is discussed. - Highlights: • CoFe{sub 2}O{sub 4} nanoparticles were prepared by facile hydrothermal method from Co–Fe oleate. • Blocking temperature (T{sub B}) is 180–330 K for 6–10.5 nm oleate-coated particles. • The apparent T{sub B} changes with oleic acid, citrate or TiO{sub 2} coating.

Inhomogeneous and anisotropic particles in optical traps: Physical behaviour and applications

Science.gov (United States)

Simpson, S. H.

2014-10-01

Beyond the ubiquitous colloidal sphere, optical tweezers are capable of trapping myriad exotic particles with wildly varying geometries and compositions. This simple fact opens up numerous opportunities for micro-manipulation, directed assembly and characterization of novel nanostructures. Furthermore, the mechanical properties of optical tweezers are transformed by their contents. For example, traps capable of measuring, or applying, femto-Newton scale forces with nanometric spatial resolution can be designed. Analogous, if not superior, angular sensitivity can be achieved, enabling the creation of exquisitely sensitive torque wrenches. These capacities, and others, lead to a multitude of novel applications in the meso- and nanosciences. In this article we review experimental and theoretical work on the relationship between particle geometry, composition and trap properties. A range of associated metrological techniques are discussed.

Influence of Ca amount on the synthesis of Nd{sub 2}Fe{sub 14}B particles in reduction–diffusion process

Energy Technology Data Exchange (ETDEWEB)

Chen, Chun-Qiang [Powder and Ceramics Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of); Department of Advanced Materials, University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Kim, Dongsoo, E-mail: dskim@kims.re.kr [Powder and Ceramics Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of); Choi, Chuljin [Powder and Ceramics Division, Korea Institute of Materials Science, Changwon, Gyeongnam 642-831 (Korea, Republic of)

2014-04-15

Nd{sub 2}Fe{sub 14}B alloy particles with high coercivity of more than 10 kOe were successfully synthesized by adjusting the amount of Calcium (Ca) in reduction–diffusion (R–D) process. Calcium oxide (CaO) and unreacted Ca remained after R–D process in particles prepared by heat treatment in Hydrogen (H{sub 2}) atmosphere at previous step. In the ratio of 0.4 of Ca to powders (Ca/powders, wt%), residual Ca was not detected from X-ray diffraction pattern. On the other hand, Ca appeared above the ratio of 1.0 and below the ratio of 0.2, amount of Ca was not enough to reduce Nd oxide. Moreover, excess Ca affected magnetic property of final products obtained after washing, because residual Ca gave rise to evolution of H{sub 2} gas during disintegration with water and it led to the formation of Nd{sub 2}Fe{sub 14}BH{sub x} (x=1–5). Finally, Nd{sub 2}Fe{sub 14}B magnetic particles were synthesized after washing in de-ionized water with a mean size of 2 μm and their maximum energy product showed 15.5 MGOe. - Highlights: • We employ spray drying for the preparation of precursor powders. • Critical amount of Ca for the reduction of Nd-oxides is revealed quantitatively. • The formation of Nd{sub 2}Fe{sub 14}BH{sub x} (x=1–5) occur in the Ca to powder ratio above 2.0. • Final products after washing and drying show more than 10 MGOe of (BH){sub max}. • We propose the optimum amount of Ca in reduction–diffusion process.

Influence of mineralizer agents on the growth of crystalline CeO{sub 2} nanospheres by the microwave-hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Deus, R.C. [Universidade Estadual Paulista-Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333 Bairro Portal das Colinas, CEP 12516-410 Guaratingueta-SP (Brazil); Cilense, M.; Foschini, C.R. [Universidade Estadual Paulista-Unesp - Instituto de Quimica - Laboratorio Interdisciplinar em Ceramica (LIEC), Rua Professor Francisco Degni s/n, CEP 14800-90 Araraquara, SP (Brazil); Ramirez, M.A. [Universidade Estadual Paulista-Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333 Bairro Portal das Colinas, CEP 12516-410 Guaratingueta-SP (Brazil); Longo, E. [Universidade Estadual Paulista-Unesp - Instituto de Quimica - Laboratorio Interdisciplinar em Ceramica (LIEC), Rua Professor Francisco Degni s/n, CEP 14800-90 Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Estadual Paulista-Unesp - Faculdade de Engenharia de Guaratingueta, Av. Dr. Ariberto Pereira da Cunha, 333 Bairro Portal das Colinas, CEP 12516-410 Guaratingueta-SP (Brazil); Universidade Federal de Itajuba-Unifei - Campus Itabira, Rua Sao Paulo, 377 Bairro Amazonas, CEP 35900-37 Itabira, MG (Brazil)

2013-02-15

Cystalline ceria (CeO{sub 2}) nanoparticles have been synthesized by a simple and fast microwave-assisted hydrothermal (MAH) under NaOH, KOH, and NH{sub 4}OH mineralizers added to a cerium ammonium nitrate aqueous solution. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transformed-IR and Raman spectroscopies. Rietveld refinement reveals a cubic structure with a space group Fm3m while infrared data showed few traces of nitrates. Field emission scanning microcopy (FEG-SEM) revealed a homogeneous size distribution of nanometric CeO{sub 2} nanoparticles. The MAH process in KOH and NaOH showed most effective to dehydrate the adsorbed water and decrease the hydrogen bonding effect leaving a weakly agglomerated powder of hydrated ceria. TEM micrographs of CeO{sub 2} synthesized under MAH conditions reveal particles well-dispersed and homogeneously distributed. The MAH enabled cerium oxide to be synthesized at 100 Degree-Sign C for 8 min.

Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

Directory of Open Access Journals (Sweden)

E. Asmi

2010-05-01

Full Text Available The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

Size-resolved fluxes of sub-100-nm particles over forests

DEFF Research Database (Denmark)

Pryor, Sara; Barthelmie, Rebecca Jane; Spaulding, A.M.

2009-01-01

Dry deposition of atmospheric particles is critically dependent on particle size and plays a key role in dictating the mass and number distributions of atmospheric particles. However, modeling dry deposition is constrained by a lack of understanding of controlling dependencies and accurate size......-resolved observations. We present size-resolved particle number fluxes for sub-100-nm particle diameters (Dp) over a deciduous forest derived using eddy covariance applied to data from a fast mobility particle sizer. The size-resolved particle number fluxes in 18 diameters between 8 and 100 nm were collected during...... leaf-on and are statistically robust. Particle deposition velocities normalized by friction velocity (v d +) are approximately four times smaller than comparable values for coniferous forests reported elsewhere. Comparison of the data with output from a new one-dimensional mechanistic particle...

Femosecond dynamics of quasi-particles in YBa sub 2 Cu sub 3 O sub 7 minus. delta. superconductor films

Energy Technology Data Exchange (ETDEWEB)

Han, S.G.; Vardeny, Z.V.; Symko, O.G. (Utah Univ., Salt Lake City, UT (United States). Dept. of Physics); Koren, G. (Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Physics)

1991-03-01

This paper reports on the transient electronic response of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} epitaxially grown HT{sub c} superconductor thin films in the femtosecond time domain, using transient photoinduced reflectivity ({Delta}R) with 60 fsec time resolution. For temperatures T {gt} T{sub c} only a bolometric signal was observed with {Delta}R {gt} O. For T {lt} T{sub c} {Delta}R {lt} O with a temperature dependent rise time of order 300 fsec followed by a relaxation (of order 3 psec) into a state with {Delta} are explained in terms of quasi-particle (QP) electronic response giving {Delta}R {lt} O. Thus the femtosecond rise time is interpreted as avalanche multiplication of QP across the gap 2{Delta} and the subsequent picosecond relaxation as QP recombination. The QP optical response is explained within the two fluid model.

Investigations of percutaneous uptake of ultrafine TiO{sub 2} particles at the high energy ion nanoprobe LIPSION

Energy Technology Data Exchange (ETDEWEB)

Menzel, F. E-mail: fmenzel@physik.uni-leipzig.de; Reinert, T.; Vogt, J.; Butz, T

2004-06-01

Micronised TiO{sub 2} particles with a diameter of about 15 nm are used in sunscreens as physical UV filter. Due to the small particle size it may be supposed that TiO{sub 2} particles can pass through the uppermost horny skin layer (stratum corneum) via intercellular channels and penetrate into deeper vital skin layers. Accumulations of TiO{sub 2} particles in the skin can decrease the threshold for allergies of the immune system or cause allergic reactions directly. Spatially resolved ion beam analysis (PIXE, RBS, STIM and secondary electron imaging) was carried out on freeze-dried cross-sections of biopsies of pig skin, on which four different formulations containing TiO{sub 2} particles were applied. The investigations were carried out at the high energy ion nanoprobe LIPSION in Leipzig with a 2.25 MeV proton beam, which was focused to a diameter of 1 {mu}m. The analysis concentrated on the penetration depth and on pathways of the TiO{sub 2} particles into the skin. In these measurements a penetration of TiO{sub 2} particles through the s. corneum into the underlying stratum granulosum via intercellular space was found. Hair follicles do not seem to be important penetration pathways because no TiO{sub 2} was detected inside. The TiO{sub 2} particle concentration in the stratum spinosum was below the minimum detection limit of about 1 particle/{mu}m{sup 2}. These findings show the importance of coating the TiO{sub 2} particles in order to prevent damage of RNA and DNA of skin cells by photocatalytic reactions of the penetrated particles caused by absorption of UV light.

Generation and evolution of nanoscale AlP and Al{sub 13}Fe{sub 4} particles in Al-Fe-P system

Energy Technology Data Exchange (ETDEWEB)

Qiao, Huan; Gao, Tong; Zhu, Xiangzhen; Wu, Yuying; Qian, Zhao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

2015-02-15

Highlights: • Diffusion and gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al{sub 13}Fe{sub 4} clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al{sub 13}Fe{sub 4} nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated.

Progress Towards a Benchtop Energetics Capability (BRIEFING CHARTS)

National Research Council Canada - National Science Library

Fajardo, Mario E; Lewis, William K

2006-01-01

The incorporation of nanometric (sub-micron size) metal fuel and oxidizer particles into energetic materials is a promising approach to increasing significantly the systems-level performance of munitions...

Evolution of metastable state molecules N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

Energy Technology Data Exchange (ETDEWEB)

Gao Liang; Sun Jizhong; Feng Chunlei; Bai Jing; Ding Hongbin [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China)

2012-01-15

A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density can achieve a value in the order of 10{sup 9} cm{sup -3}. The N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density at such a value could be easily detected by laser-based experimental methods.

Viability Study of a Safe Method for Health to Prepare Cement Pastes with Simultaneous Nanometric Functional Additions

Directory of Open Access Journals (Sweden)

M. A. de la Rubia

2018-01-01

Full Text Available The use of a mixing method based on a novel dry dispersion procedure that enables a proper mixing of simultaneous nanometric functional additions while avoiding the health risks derived from the exposure to nanoparticles is reported and compared with a common manual mixing in this work. Such a dry dispersion method allows a greater workability by avoiding problems associated with the dispersion of the particles. The two mixing methods have been used to prepare Portland cement CEM I 52.5R pastes with additions of nano-ZnO with bactericide properties and micro- or nanopozzolanic SiO2. The hydration process performed by both mixing methods is compared in order to determine the efficiency of using the method. The hydration analysis of these cement pastes is carried out at different ages (from one to twenty-eight days by means of differential thermal analysis and thermogravimetry (DTA-TG, X-ray diffraction (XRD, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy (FTIR analyses. Regardless of composition, all the mixtures of cement pastes obtained by the novel dispersion method showed a higher retardation of cement hydration at intermediate ages which did not occur at higher ages. In agreement with the resulting hydration behaviour, the use of this new dispersion method makes it possible to prepare homogeneous cement pastes with simultaneous functional nanoparticles which are physically supported on the larger particles of cement, avoiding exposure to the nanoparticles and therefore minimizing health risks. Manual mixing of cement-based materials with simultaneous nanometric functional nanoparticles on a large scale would make it difficult to obtain a homogenous material together with the health risks derived from the handling of nanoparticles.

Efficient perovskite light-emitting diodes featuring nanometre-sized crystallites

Science.gov (United States)

Xiao, Zhengguo; Kerner, Ross A.; Zhao, Lianfeng; Tran, Nhu L.; Lee, Kyung Min; Koh, Tae-Wook; Scholes, Gregory D.; Rand, Barry P.

2017-01-01

Organic-inorganic hybrid perovskite materials are emerging as highly attractive semiconductors for use in optoelectronics. In addition to their use in photovoltaics, perovskites are promising for realizing light-emitting diodes (LEDs) due to their high colour purity, low non-radiative recombination rates and tunable bandgap. Here, we report highly efficient perovskite LEDs enabled through the formation of self-assembled, nanometre-sized crystallites. Large-group ammonium halides added to the perovskite precursor solution act as a surfactant that dramatically constrains the growth of 3D perovskite grains during film forming, producing crystallites with dimensions as small as 10 nm and film roughness of less than 1 nm. Coating these nanometre-sized perovskite grains with longer-chain organic cations yields highly efficient emitters, resulting in LEDs that operate with external quantum efficiencies of 10.4% for the methylammonium lead iodide system and 9.3% for the methylammonium lead bromide system, with significantly improved shelf and operational stability.

Improvement of (La{sub 0.74}Bi{sub 0.10}Sr{sub 0.16})MnO{sub 3}-Bi{sub 1.4}Er{sub 0.6}O{sub 3} composite cathodes for intermediate-temperature solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Li, Junliang; Wang, Shaorong; Sun, Xiufu; Liu, Renzhu; Ye, Xiaofeng; Wen, Zhaoyin [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

2008-12-01

Porous composite cathodes including (La{sub 0.74}Bi{sub 0.10}Sr{sub 0.16})MnO{sub 3-{delta}} (LBSM) and Bi{sub 1.4}Er{sub 0.6}O{sub 3} (ESB) were fabricated and characterized using AC impedance spectroscopy. In our earlier work, the growth and aggregation of ESB particles were found in LBSM-ESB composite cathodes. In this study, therefore, two approaches were used to restrain the growth and aggregation of ESB particles. First, the sintering temperature of the composite cathode was reduced by introducing a sintering function layer, which caused a 22% reduction in the initial polarization resistance (R), but the cathode polarization resistance decreased at a rate of 2.15 x 10{sup -4} {omega} cm{sup 2} h{sup -1} at 700 C during a period of 100 h. Second, nano-sized Gd-doped ceria powder (CGO) was added to the composite cathode system. Stability improvement was achieved at 10 vol% CGO, and the degradation rate at 700 C was 4.01 x 10{sup -5} {omega} cm{sup 2} h{sup -1} during a period of 100 h. (author)

Structural and Mössbauer studies of nanocrystalline Mn{sup 4+}-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} particles prepared by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Widatallah, H. M., E-mail: hishammw@squ.edu.om; Al-Mabsali, F. N.; Al-Hajri, F. S. [Sultan Qaboos University, Physics Department, College of Science (Oman); Khalifa, N. O. [University of Khartoum, Physics Department, Faculty of Science (Sudan); Gismelseed, A. M.; Al-Rawas, A. D.; Elzain, M.; Yousif, A. [Sultan Qaboos University, Physics Department, College of Science (Oman)

2016-12-15

The structure and magnetic properties of spinel-related Mn{sup 4+}-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} nanocrystalline particles of the composition Li{sub 0.5}Fe{sub 2.25}Mn{sub 0.1875}O{sub 4}, prepared by milling a pristine sample for different times, were investigated. The average crystallite and particle size, respectively, decreased form ∼40 nm to ∼10 nm and ∼2.5 μm to ∼10 nm with increasing milling time from 0 h to 70 h. Rietveld refinement of the XRD data of the non-milled sample show the Mn{sup 4+} dopant ions to substitute for Fe{sup 3+} at the octahedral B-sites of the spinel-related structure. The Mössbauer spectra of the milled ferrites indicate that more particles turn superparamagnetic with increasing milling time. The Mössbauer data collected at 78 K suggest that while in the non-milled sample the Mn{sup 4+} ions substitute for Fe{sup 3+} at the octahedral B-sites, this is reversed as milling proceeds with doped Mn{sup 4+} ions, balancing Fe{sup 3+} vacancies and possibly Li{sup +} ions progressively migrate to the tetrahedral A-sites. This is supported by the slight increase observed in the magnetization of the milled samples relative to that of the non-milled one. The magnetic data suggest that in addition to the increasing superparamagentic component of the milled particles, thermal spin reversal and/or spin canting effects are possible at the surface layers of the nanoparticles.

Fluoride adsorption from aqueous solution by magnetic core-shell Fe{sub 3}O{sub 4}@alginate-La particles fabricated via electro-coextrusion

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yahui [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China); Lin, Xiaoyan, E-mail: lxy20100205@163.com [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, Sichuan (China); Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China); Zhou, Quisheng [A State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Xuegang [Engineering Research Center of Biomass Materials, Ministry of Education, Mianyang 621010, Sichuan (China)

2016-12-15

Graphical abstract: The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. - Highlights: • Magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were prepared by electro-coextrusion. • The maximum adsorption capacity for fluoride at 298.15 K was 45.230 mg/g. • The adsorbent has a good saturation magnetization value. • The adsorbent has a great potential in removing the fluoride. - Abstract: The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. Main factors affecting the removal of fluoride, including pH, adsorbent dosage, initial concentration, temperature and contact time were investigated. The adsorption isotherm and adsorption kinetics were studied to understand the adsorption process in detail. The experimental data were fitted well by the non-linear Freundlich isotherm and linear pseudo-second-order model, the maximum fluoride adsorption capacity was 45.230 mg/g at pH 4, 298.15 K. Thermodynamic parameters indicated that the fluoride adsorption process was feasible and spontaneous. The presence of other anions like Cl{sup −}, SO{sub 4}{sup 2−}, HCO{sub 3}{sup −} and PO{sub 4}{sup 3−} had almost no effect on the fluoride adsorption. The adsorbent can be easily separated from the solution by a magnet. The magnetic core-shell Fe{sub 3}O{sub 4}@Alg-La particles before and after fluoride adsorption were studied by SEM, FTIR, EDX and XPS, which indicated that the adsorption mechanism may be related to electrostatic attraction and Lewis acid-base interaction.

Fluidized bed combustion of single coal char particles at high CO{sub 2} concentration

Energy Technology Data Exchange (ETDEWEB)

Scala, F.; Chirone, R. [CNR, Naples (Italy)

2010-12-15

Combustion of single coal char particles was studied at 850{sup o}C in a lab-scale fluidized bed at high CO{sub 2} concentration, typical of oxyfiring conditions. The burning rate of the particles was followed as a function of time by continuously measuring the outlet CO and O{sub 2} concentrations. Some preliminary evaluations on the significance of homogeneous CO oxidation in the reactor and of carbon gasification by CO{sub 2} in the char were also carried out. Results showed that the carbon burning rate increases with oxygen concentration and char particle size. The particle temperature is approximately equal to that of the bed up to an oxygen concentration of 2%, but it is considerably higher for larger oxygen concentrations. Both CO{sub 2} gasification of char and homogeneous CO oxidation are not negligible. The gasification reaction rate is slow and it is likely to be controlled by intrinsic kinetics. During purely gasification conditions the extent of carbon loss due to particle attrition by abrasion (estimated from the carbon mass balance) appears to be much more important than under combustion conditions.

Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

Energy Technology Data Exchange (ETDEWEB)

Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

2011-06-15

Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

The role of low-volatility organic compounds in initial particle growth in the atmosphere

CERN Document Server

Tröstl, Jasmin; Gordon, Hamish; Heinritzi, Martin; Yan, Chao; Molteni, Ugo; Ahlm, Lars; Frege, Carla; Bianchi, Federico; Wagner, Robert; Simon, Mario; Lehtipalo, Katrianne; Williamson, Christina; Craven, Jill S; Duplissy, Jonathan; Adamov, Alexey; Almeida, Joao; Bernhammer, Anne-Kathrin; Breitenlechner, Martin; Brilke, Sophia; Dias, Antònio; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Fuchs, Claudia; Guida, Roberto; Gysel, Martin; Hansel, Armin; Hoyle, Christopher R; Jokinen, Tuija; Junninen, Heikki; Kangasluoma, Juha; Keskinen, Helmi; Kim, Jaeseok; Krapf, Manuel; Kürten, Andreas; Laaksonen, Ari; Lawler, Michael; Leiminger, Markus; Mathot, Serge; Möhler, Ottmar; Nieminen, Tuomo; Onnela, Antti; Petäjä, Tuukka; Piel, Felix M; Miettinen, Pasi; Rissanen, Matti P; Rondo, Linda; Sarnela, Nina; Schobesberger, Siegfried; Sengupta, Kamalika; Sipilä, Mikko; Smith, James; Steiner, Gerhard; Tomè, Antònio; Virtanen, Annele; Wagner, Andrea C; Weingartner, Ernest; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Carslaw, Kenneth S; Curtius, Joachim; Dommen, Josef; Kirkby, Jasper; Kulmala, Markku; Riipinen, Ilona; Worsnop, Douglas R; Donahue, Neil M; Baltensperger, Urs

2016-01-01

About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer. Although recent studies predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon, and the presence of a possible Kelv...

Particle size, spin wave and surface effects on magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Aslibeiki, B., E-mail: b.aslibeiki@tabrizu.ac.ir [Department of Physics, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Varvaro, G.; Peddis, D. [Istituto di Struttura della Materia, National Research Council, Monterotondo Scalo, Roma 00015 (Italy); Kameli, P. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2017-01-15

Magnesium ferrite, MgFe{sub 2}O{sub 4}, nanoparticles with a mean diameter varying from ∼6 to ∼17 nm were successfully synthesized using a simple thermal decomposition method at different annealing temperatures ranging in between 400 and 600 °C. Pure spinel ferrite nanoparticles were obtained at temperatures lower than 500 °C, while the presence of hematite (α-Fe{sub 2}O{sub 3}) impurities was observed at higher temperatures. Single-phase samples show a superparamagnetic behavior at 300 K, the saturation magnetization (M{sub s}) becoming larger with the increase of particles size. The temperature dependence of M{sub s} was explained in terms of surface spin-canting as well as spin wave excitations in the core. Using a modified Bloch law, [M{sub s}(T)=M{sub s}(0)(1−βT{sup α})], we observed a size dependent behavior of the Bloch constant β and the exponent α, whose values increase and decrease, respectively, as the particle size reduces. - Highlights: • MgFe{sub 2}O{sub 4} nanoparticles were synthesized using a thermal decomposition method. • Pure ferrite nanoparticles were obtained at temperatures lower than 500 °C. • Samples show a superparamagnetic behavior at room temperatures. • Spin wave excitations were studied using a modified Bloch law.

A method for measuring particle number emissions from vehicles driving on the road.

Science.gov (United States)

Shi, J P; Harrison, R M; Evans, D E; Alam, A; Barnes, C; Carter, G

2002-01-01

Earlier research has demonstrated that the conditions of dilution of engine exhaust gases profoundly influence the size distribution and total number of particles emitted. Since real world dilution conditions are variable and therefore difficult to simulate, this research has sought to develop and validate a method for measuring particle number emissions from vehicles driving past on a road. This has been achieved successfully using carbon dioxide as a tracer of exhaust gas dilution. By subsequent adjustment of data to a constant dilution factor, it is possible to compare emissions from different vehicles using different technologies and fuels based upon real world emission data. Whilst further optimisation of the technique, especially in terms of matching the instrument response times is desirable, the measurements offer useful insights into emissions from gasoline and diesel vehicles, and the substantial proportion of particles emitted in the 3-7 nanometre size range.

Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

Energy Technology Data Exchange (ETDEWEB)

Uzu, G. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: gaelle.uzu@ensat.fr; Sobanska, S. [LASIR UMR 8516, Universite des Sciences et Technologies de Lille, Batiment C5, 59655 Villeneuve d' Ascq Cedex (France)], E-mail: Sophie.Sobanska@univ-lille1.fr; Aliouane, Y. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France); Pradere, P. [Chemical Metal Treatment Company, STCM, 30-32 chemin de Fondeyre, 31200 Toulouse (France)], E-mail: p.pradere@stc-metaux.com; Dumat, C. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: camille.dumat@ensat.fr

2009-04-15

Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 {+-} 20 mg Pb kg{sup -1}) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO{sub 4}, PbSO{sub 4}.PbO, {alpha}-PbO and Pb{sup 0}. Morphology investigations revealed that PM{sub 2.5} (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 {mu}m or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl{sub 2} extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size.

Particle size effect on microwave absorbing of La{sub 0.67}Ba{sub 0.33}Mn{sub 0.94}Ti{sub 0.06}O{sub 3} powders prepared by mechanical alloying with the assistance of ultrasonic irradiation

Energy Technology Data Exchange (ETDEWEB)

Saptari, Sitti Ahmiatri, E-mail: siti-ahmiatri@yahoo.co.id [Faculty of Science and Technology, State Islamic University, Jakarta (Indonesia); Manaf, Azwar; Kurniawan, Budhy [Departement of Physics, University of Indonesia, Depok (Indonesia)

2016-03-11

Doped manganites have attracted substantial interest due to their unique chemical and physics properties, which makes it possible to be used for microwave absorbing materials. In this paper we report synthesizes and characterization of La{sub 0.67}Ba{sub 0.33}Mn{sub 0.94}Ti{sub 0.06}O{sub 3} powders prepared by mechanical alloying with the assistance of a high power ultrasonic treatment. After solid state reaction, the presence of single phase was confirmed by X-ray Diffraction (XRD). Refinement results showed that samples are single phase with monoclinic structure. It was found that powder materials derived from mechanical alloying results in large variation in the particle size. A significant improvement was obtained upon subjecting the mechanically milled powder materials to an ultrasonication treatment for a relatively short period of time. As determined by particle size analyzer (PSA), the mean particle size gradually decreased from the original size of 5.02 µm to 0.36 µm. Magnetic properties were characterized by VSM, and hysteresis loops results showed that samples are soft magnetic. It was found that when the mean particle size decreases, saturation was increases and coersitivity was decreases. Microwave absorption properties were investigated in the frequency range of 8-12 GHz using vector network analyzer. An optimal reflection loss of 24.44 dB is reached at 11.4 GHz.

Nano ZrO{sub 2} particles in nanocrystalline Fe–14Cr–1.5Zr alloy powders

Energy Technology Data Exchange (ETDEWEB)

Xu, W.Z.; Li, L.L.; Saber, M.; Koch, C.C.; Zhu, Y.T., E-mail: ytzhu@ncsu.edu; Scattergood, R.O.

2014-09-15

Here we report on the formation of nano ZrO{sub 2} particles in Fe–14Cr–1.5Zr alloy powders synthesized by mechanical alloying. The nano ZrO{sub 2} particles were found uniformly dispersed in the ferritic matrix powders with an average size of about 3.7 nm, which rendered the alloy powders so stable that it retained nanocrystalline structure after annealing at 900 °C for 1 h. The ZrO{sub 2} nanoparticles have a tetragonal crystal structure and the following orientation relationship with the matrix: (0 0 2){sub ZrO2}//(0 0 2){sub Matrix} and [0 1 0]{sub ZrO2}//[1 2 0]{sub Matrix}. The size and dispersion of the ZrO{sub 2} particles are comparable to those of Y–Ti–O enriched oxides reported in irradiation-resistant ODS alloys. This suggests a potential application of the new alloy powders for nuclear energy applications.

Hydroxide precursors to produce nanometric YCrO{sub 3}: Characterization and conductivity analysis

Energy Technology Data Exchange (ETDEWEB)

Durán, A., E-mail: dural@cnyn.unam.mx [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800, Ensenada, B.C. (Mexico); Meza F, C. [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800, Ensenada, B.C. (Mexico); Arizaga, Gregorio Guadalupe Carbajal, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

2012-06-15

Highlights: ► Y/Cr mixed hydroxide was precipitated with gaseous ammonia. ► The hydroxide treated at 1373 K formed YCrO{sub 3} crystals with 20 nm diameter. ► Electrical properties were different than those found in other methods of synthesis. ► E{sub act} suggests small-polarons as conduction mechanisms. -- Abstract: A precursor to produce perovskite-type YCrO{sub 3} was precipitated by bubbling gaseous ammonia into an yttrium/chromium salts solution. X-ray diffraction showed that the as-prepared powders were amorphous. Thermal treatment between 1273 and 1373 K, leads to formation of polycrystalline YCrO{sub 3} with crystal sizes around 20 nm. High resolution X-ray photoelectron spectra showed uniform chemical environment for yttrium and chromium in the amorphous hydroxide and crystalline YCrO{sub 3}. Shifts between Y 3d{sub 5/2} and Cr 2p{sub 3/2} binding energy suggest redistribution or charge transfer between yttrium and chromium ions in the YCrO{sub 3} structure. The electrical properties of YCrO{sub 3}, whose precursors were precipitated with gaseous ammonia are different than those prepared by combustion synthesis. Electrical conductivity presents a sudden increase at ∼473 K, which is associated to the grain size and morphology of the crystallites. The redistribution of charge between Y(III) and Cr(III) is thermally activated by the hopping of small-polarons, which are characterized by the Arrhenius law as the conductive mechanism.

Achieving swift equilibration of a Brownian particle using flow-fields

Science.gov (United States)

Patra, Ayoti; Jarzynski, Christopher

Can a system be driven to a targeted equilibrium state on a timescale that is much shorter than its natural equilibration time? In a recent experiment, the swift equilibration of an overdamped Brownian particle was achieved by use of an appropriately designed, time-dependent optical trap potential. Motivated by these results, we develop a general theoretical approach for guiding an ensemble of Brownian particles to track the instantaneous equilibrium distribution of a desired potential U (q , t) . In our approach, we use flow-fields associated with the parametric evolution of the targeted equilibrium state to construct an auxiliary potential U (q , t) , such that dynamics under the composite potential U (t) + U (t) achieves the desired evolution. Our results establish a close connection between the swift equilibration of Brownian particles, quantum shortcuts to adiabaticity, and the dissipationless driving of a classical, Hamiltonian system.

Engineering a Biocompatible Scaffold with Either Micrometre or Nanometre Scale Surface Topography for Promoting Protein Adsorption and Cellular Response

Directory of Open Access Journals (Sweden)

Xuan Le

2013-01-01

Full Text Available Surface topographical features on biomaterials, both at the submicrometre and nanometre scales, are known to influence the physicochemical interactions between biological processes involving proteins and cells. The nanometre-structured surface features tend to resemble the extracellular matrix, the natural environment in which cells live, communicate, and work together. It is believed that by engineering a well-defined nanometre scale surface topography, it should be possible to induce appropriate surface signals that can be used to manipulate cell function in a similar manner to the extracellular matrix. Therefore, there is a need to investigate, understand, and ultimately have the ability to produce tailor-made nanometre scale surface topographies with suitable surface chemistry to promote favourable biological interactions similar to those of the extracellular matrix. Recent advances in nanoscience and nanotechnology have produced many new nanomaterials and numerous manufacturing techniques that have the potential to significantly improve several fields such as biological sensing, cell culture technology, surgical implants, and medical devices. For these fields to progress, there is a definite need to develop a detailed understanding of the interaction between biological systems and fabricated surface structures at both the micrometre and nanometre scales.

Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO{sub 2} particles

Energy Technology Data Exchange (ETDEWEB)

Cui, Chaopeng; Gao, Yimin; Zhou, Yucheng [Xi' an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi' an, Shaanxi Province (China); Wei, Shizhong [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China); Henan University of Science and Technology, Engineering Research Center of Tribology and Materials Protection, Ministry of Education, Luoyang (China); Zhang, Guoshang; Zhu, Xiangwei; Guo, Songliang [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China)

2016-03-15

The nano-sized ZrO{sub 2}-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO{sub 2} particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO{sub 2} particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO{sub 2} particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

Fabrication of magnetic and fluorescent chitin and dibutyrylchitin sub-micron particles by oil-in-water emulsification.

Science.gov (United States)

Blanco-Fernandez, Barbara; Chakravarty, Shatadru; Nkansah, Michael K; Shapiro, Erik M

2016-11-01

Chitin is a carbohydrate polymer with unique pharmacological and immunological properties, however, because of its unwieldy chemistry, the synthesis of discreet sized sub-micron particles has not been well reported. This work describes a facile and flexible method to fabricate biocompatible chitin and dibutyrylchitin sub-micron particles. This technique is based on an oil-in-water emulsification/evaporation method and involves the hydrophobization of chitin by the addition of labile butyryl groups onto chitin, disrupting intermolecular hydrogen bonds and enabling solubility in the organic solvent used as the oil phase during fabrication. The subsequent removal of butyryl groups post-fabrication through alkaline saponification regenerates native chitin while keeping particles morphology intact. Examples of encapsulation of hydrophobic dyes and nanocrystals are demonstrated, specifically using iron oxide nanocrystals and coumarin 6. The prepared particles had diameters between 300-400nm for dibutyrylchitin and 500-600nm for chitin and were highly cytocompatible. Moreover, they were able to encapsulate high amounts of iron oxide nanocrystals and were able to label mammalian cells. We describe a technique to prepare sub-micron particles of highly acetylated chitin (>90%) and dibutyrylchitin and demonstrate their utility as carriers for imaging. Chitin is a polysaccharide capable of stimulating the immune system, a property that depends on the acetamide groups, but its insolubility limits its use. No method for sub-micron particle preparation with highly acetylated chitins have been published. The only approach for the preparation of sub-micron particles uses low acetylation chitins. Dibutyrylchitin, a soluble chitin derivative, was used to prepare particles by oil in water emulsification. Butyryl groups were then removed, forming chitin particles. These particles could be suitable for encapsulation of hydrophobic payloads for drug delivery and cell imaging, as well as

Synthesis and characterization particles of Ba{sub 0,50}Sr{sub 0,50}Co{sub 0,80}Fe{sub 0,20}O{sub 3} obtained by the citrate-EDTA technique; Sintese e caracterizacao de particulados de Ba{sub 0,50}Sr{sub 0,50}Co{sub 0,80}Fe{sub 0,20}O{sub 3} obtidos pela tecnica dos citratos-EDTA

Energy Technology Data Exchange (ETDEWEB)

Bonturim, E; Vargas, R A; Andreoli, M; Seo, E S.M., [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

2010-07-01

The Ba{sub (1-x)}Sr{sub (x)}Co{sub (1-y)}Fe{sub (y)}O{sub (3)} (BSCF) has been studied as a cathode material for Intermediate Temperature Solid Oxide Fuel Cell, due to its better ion and electron conduction. This work aims to study the synthesis of the compound obtained from the citrate-EDTA technique. Thermogravimetric analysis indicated the formation of the compound above 800 deg C. The materials calcined at temperatures of 700, 800 and 900 deg C for 5 h showed cubic pseudo-perovskite structure, according to the literature. By analysis of X-ray fluorescence were obtained powders with nominal chemical composition in the temperature range studied. The micrographs obtained by SEM and particle size distribution analysis showed the formation of particle with diameters below 1 micron. (author)

Anisotropy of Single-Crystal Silicon in Nanometric Cutting.

Science.gov (United States)

Wang, Zhiguo; Chen, Jiaxuan; Wang, Guilian; Bai, Qingshun; Liang, Yingchun

2017-12-01

The anisotropy exhibited by single-crystal silicon in nanometric cutting is very significant. In order to profoundly understand the effect of crystal anisotropy on cutting behaviors, a large-scale molecular dynamics model was conducted to simulate the nanometric cutting of single-crystal silicon in the (100)[0-10], (100)[0-1-1], (110)[-110], (110)[00-1], (111)[-101], and (111)[-12-1] crystal directions in this study. The simulation results show the variations of different degrees in chip, subsurface damage, cutting force, and friction coefficient with changes in crystal plane and crystal direction. Shear deformation is the formation mechanism of subsurface damage, and the direction and complexity it forms are the primary causes that result in the anisotropy of subsurface damage. Structurally, chips could be classified into completely amorphous ones and incompletely amorphous ones containing a few crystallites. The formation mechanism of the former is high-pressure phase transformation, while the latter is obtained under the combined action of high-pressure phase transformation and cleavage. Based on an analysis of the material removal mode, it can be found that compared with the other crystal direction on the same crystal plane, the (100)[0-10], (110)[-110], and (111)[-101] directions are more suitable for ductile cutting.

Statistical evaluation of potential damage to the Al(OH){sub 3} layer on nTiO{sub 2} particles in the presence of swimming pool and seawater

Energy Technology Data Exchange (ETDEWEB)

Virkutyte, Jurate [Pegasus Technical Services, Inc (United States); Al-Abed, Souhail R., E-mail: al-abed.souhail@epa.gov [U.S. Environmental Protection Agency, National Risk Management Research Laboratory (United States)

2012-03-15

Nanosized TiO{sub 2} particles (nTiO{sub 2}) are usually coated with an Al(OH){sub 3} layer when used in sunscreen to shield against the harmful effects of free radicals that are generated when these particles are exposed to UV radiation. Therefore, it is vital to insure the structural stability of these particles in the environment where the protective layer may be damaged and adverse health and environmental effects can occur. This study utilized X-ray analysis (SEM-EDS) to provide a qualitative and semi-quantitative assessment of the chemical and physical characteristics of Al(OH){sub 3}-coated original and damaged nTiO{sub 2} particles (used in sunscreen lotion formulations) in the presence of both swimming pool and seawater. Also, by utilizing statistical tools, a distribution of Al/Ti (%) on the particle surface was determined and evaluated. It was found that 45 min of treatment with swimming pool and seawater significantly induced the redistribution of Al/Ti (%), which changed the surface characteristics of particles and, therefore, may have induced undesired photo-activity and the consequent formation of free radicals.

The oldest magnetic record in our solar system identified using nanometric imaging and numerical modeling.

Science.gov (United States)

Shah, Jay; Williams, Wyn; Almeida, Trevor P; Nagy, Lesleis; Muxworthy, Adrian R; Kovács, András; Valdez-Grijalva, Miguel A; Fabian, Karl; Russell, Sara S; Genge, Matthew J; Dunin-Borkowski, Rafal E

2018-03-21

Recordings of magnetic fields, thought to be crucial to our solar system's rapid accretion, are potentially retained in unaltered nanometric low-Ni kamacite (~ metallic Fe) grains encased within dusty olivine crystals, found in the chondrules of unequilibrated chondrites. However, most of these kamacite grains are magnetically non-uniform, so their ability to retain four-billion-year-old magnetic recordings cannot be estimated by previous theories, which assume only uniform magnetization. Here, we demonstrate that non-uniformly magnetized nanometric kamacite grains are stable over solar system timescales and likely the primary carrier of remanence in dusty olivine. By performing in-situ temperature-dependent nanometric magnetic measurements using off-axis electron holography, we demonstrate the thermal stability of multi-vortex kamacite grains from the chondritic Bishunpur meteorite. Combined with numerical micromagnetic modeling, we determine the stability of the magnetization of these grains. Our study shows that dusty olivine kamacite grains are capable of retaining magnetic recordings from the accreting solar system.

In vivo behaviors of Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3) cement in rabbit model

Energy Technology Data Exchange (ETDEWEB)

Lin, Qing, E-mail: lnqing@yahoo.com [School of Material Engineering, Jinling Institute of Technology, Nanjing 211169 (China); Zhang, Xiaojuan [School of Material Engineering, Jinling Institute of Technology, Nanjing 211169 (China); Lu, Chunhua; Lan, Xianghui [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China); Hou, Guihua [Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051 (China); Xu, Zhongzi [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009 (China)

2016-01-01

In vivo behaviors of Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3, TCS) cement were investigated in the rabbit femoral defects using the poly(methyl methacrylate) (PMMA) as control. The deposited apatite and CaCO{sub 3} layers round TCS paste surfaces were completely used to construct the new bone tissue. TCS paste could stimulate the formation of new bone tissue in marrow tissue. The osteostimulation was mainly attributed to the proliferation and differentiation effects of Ca and Si ions released from TCS paste on the osteoprogenitor cells. However, Calcium–Silicate–Hydrate (C–S–H) gel in TCS paste was harder to degradate than Ca(OH){sub 2}. TCS paste kept the original shape during implantation, and could not provide the pores or spaces for further formation of bone tissue. Osteolytic defects induced by wear particles from TCS paste surface could not be completely avoided, because of the interfacial strain and the extensive micromotion between TCS paste surface and new bone tissue. Overall, our results indicated that Ca(OH){sub 2} activated nano SiO{sub 2} cement was bioactivity and osteostimulation. The further improvements of Ca(OH){sub 2} activated nano SiO{sub 2} cement should be done by achieving a balance between biological properties and mechanical performances. - Highlights: • Ca(OH){sub 2} activated nano SiO{sub 2} (n{sub Ca}/n{sub Si} = 3, TCS) cement was in vivo bioactivity. • Deposited apatite and CaCO{sub 3} particles round TCS paste were utilized to restructure new bone tissue. • TCS paste was able to induce osteogenesis in marrow tissue. • Wear particle could induced osteolytic defect between TCS paste and bone tissue.

Characterisation of sub-micron particle number concentrations and formation events in the western Bushveld Igneous Complex, South Africa

Directory of Open Access Journals (Sweden)

A. Hirsikko

2012-05-01

Full Text Available South Africa holds significant mineral resources, with a substantial fraction of these reserves occurring and being processed in a large geological structure termed the Bushveld Igneous Complex (BIC. The area is also highly populated by informal, semi-formal and formal residential developments. However, knowledge of air quality and research related to the atmosphere is still very limited in the area. In order to investigate the characteristics and processes affecting sub-micron particle number concentrations and formation events, air ion and aerosol particle size distributions and number concentrations, together with meteorological parameters, trace gases and particulate matter (PM were measured for over two years at Marikana in the heart of the western BIC. The observations showed that trace gas (i.e. SO<sub>2sub>, NO<sub>x>, CO and black carbon concentrations were relatively high, but in general within the limits of local air quality standards. The area was characterised by very high condensation sink due to background aerosol particles, PM<sub>10sub> and O<sub>3sub> concentration. The results indicated that high amounts of Aitken and accumulation mode particles originated from domestic burning for heating and cooking in the morning and evening, while during daytime SO<sub>2sub>-based nucleation followed by the growth by condensation of vapours from industrial, residential and natural sources was the most probable source for large number concentrations of nucleation and Aitken mode particles. Nucleation event day frequency was extremely high, i.e. 86% of the analysed days, which to the knowledge of the authors is the highest frequency ever reported. The air mass back trajectory and wind direction analyses showed that the secondary particle formation was influenced both by local and regional pollution and vapour sources. Therefore, our observation of the annual cycle and magnitude of the particle formation and growth rates during

Ground truth of (sub-)micrometre cometary dust - Results of MIDAS onboard Rosetta

Science.gov (United States)

Mannel, Thurid; Bentley, Mark; Schmied, Roland; Torkar, Klaus; Jeszenszky, Harald; Romsted, Jens; Levasseur-Regourd, A.; Weber, Iris; Jessberger, Elmar K.; Ehrenfreund, Pascale; Köberl, Christian; Havnes, Ove

2016-10-01

The investigation of comet 67P by Rosetta has allowed the comprehensive characterisation of pristine cometary dust particles ejected from the nucleus. Flying alongside the comet at distances as small as a few kilometres, and with a relative velocity of only centimetres per second, the Rosetta payload sampled almost unaltered dust. A key instrument to study this dust was MIDAS (the Micro-Imaging Dust Analysis System), a dedicated atomic force microscope that scanned the surfaces of hundreds of (sub-)micrometre sized particles in 3D with resolutions down to nanometres. This offers the unique opportunity to explore the morphology of smallest cometary dust and expand our current knowledge about cometary material.Here we give an overview of dust collected and analysed by MIDAS and highlight its most important features. These include the ubiquitous agglomerate nature of the dust, which is found at all size scales from the largest (>10 µm) through to the smallest (MIDAS resemble primitive interplanetary dust which is a strong argument for a common cometary origin.

Generation of MoS{sub 2} quantum dots by laser ablation of MoS{sub 2} particles in suspension and their photocatalytic activity for H{sub 2} generation

Energy Technology Data Exchange (ETDEWEB)

Baldoví, Herme G.; Latorre-Sánchez, Marcos; Esteve-Adell, Iván [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain); Khan, Anish; Asiri, Abdullah M. [King Abdulaziz University, Center of Excellence for Advanced Materials Research (Saudi Arabia); Kosa, Samia A. [King Abdulaziz University, Chemistry Department, Faculty of Science (Saudi Arabia); Garcia, Hermenegildo, E-mail: hgarcia@qim.upv.es [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain)

2016-08-15

MoS{sub 2} quantum dots (QDs) have been obtained in colloidal suspensions by 532 nm laser ablation (7 ns fwhp/pulse, 50 mJ/pulse) of commercial MoS{sub 2} particles in acetonitrile. High-resolution transmission electron microscopy images show a lateral size distribution from 5 to 20 nm, but a more homogeneous particle size of 20 nm can be obtained by silica gel chromatography purification in acetonitrile. MoS{sub 2} QDs obtained by laser ablation are constituted by 3–6 MoS{sub 2} layers (1.8–4 nm thickness) and exhibit photoluminescence whose λ{sub PL} varies from 430 to 530 nm depending on the excitation wavelength. As predicted by theory, the confinement effect and the larger periphery in MoS{sub 2} QDs increasing the bandgap and having catalytically active edges are reflected in an enhancement of the photocatalytic activity for H{sub 2} generation upon UV–Vis irradiation using CH{sub 3}OH as sacrificial electron donor due to the increase in the reduction potential of conduction band electrons and the electron transfer kinetics.

COOH-functionalisation of silica particles

Energy Technology Data Exchange (ETDEWEB)

Majewski, Peter, E-mail: peter.majewski@unisa.edu.au [School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, University of South Australia, Adelaide (Australia); Albrecht, Trent [Ian Wark Research Institute, University of South Australia, Adelaide (Australia); Weber, Siegfried [Department of Biotechnology, University of Applied Sciences, Mannheim (Germany)

2011-09-01

In this study COOH-functionalised silica is synthesised using phosphonateN-(phosphonomethyl)iminodiacetic acid (PMIDA) in an aqueous solution. The presence of PMIDA on the silica particles was verified using Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy and titration. Experimentally, surface concentrations of COOH functional groups of up to about 3 mmol/g{sub silica} were achieved, whereas theoretical calculation of the maximum COOH functional group concentration gave about 1 mmol/g{sub silica}. The discrepancy may be caused by PMIDA multilayer formation on the particle.

Secondary phase formation in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films and YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}/SrTiO{sub 3} superlattices

Energy Technology Data Exchange (ETDEWEB)

Johnson, C.N.L.

1996-06-01

Studies of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) thin films and YBCO/STO superlattices has been performed. The dc magnetron sputtered YBCO single layer investigation concerned the dependence of the secondary phase formation and superconducting transport properties on sputtering target and ambient gas composition. YBCO/STO superlattices, grown by dc and rf magnetron sputtering, respectively, were analyzed with respect to microstructure and formation of secondary phases. The main characterization techniques used in this study have been x-ray diffraction to identify phases and to obtain orientational relationships, scanning electron microscopy to study surface morphology, transmission electron microscopy for microstructural characterization, and energy-dispersive x-ray spectroscopy for chemical characterization. With the aim to reduce or avoid the formation of copper-rich surface particles and still maintain satisfactory superconducting transport properties, YBCO films were deposited using copper-poor or yttrium-rich sputtering targets in an Ar:O{sub 2} or Ar:O{sub 2}:N{sub 2}O sputtering gas mixture. It was found that the use of yttrium-rich targets and N{sub 2}O in the sputtering gas is a reliable way to achieve smooth films without surface particles and with satisfactory superconducting properties, while the use of copper-poor targets and N{sub 2}O deteriorates those properties. Based on the previous results, YBCO/STO superlattices were grown using yttrium-rich YBCO targets and stoichiometric STO targets, respectively, in a Ar:O{sub 2}:N{sub 2}O sputtering gas mixture. The superlattices were found to have sharp interfaces and no indications of interface reactions were detected. 61 refs, 18 figs, 3 tabs

Synthesis, characterization and hemolysis studies of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} ferrites synthesized by sol-gel for hyperthermia treatment applications

Energy Technology Data Exchange (ETDEWEB)

Jasso-Terán, Rosario Argentina, E-mail: arg.jasso@gmail.com; Cortés-Hernández, Dora Alicia; Sánchez-Fuentes, Héctor Javier; Reyes-Rodríguez, Pamela Yajaira; León-Prado, Laura Elena de; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel

2017-04-01

The synthesis of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} nanoparticles, x=0, 0.25, 0.50, 0.75 and 1.0, was performed by sol-gel method followed by a heat treatment at 400 °C for 30 min. These ferrites showed nanometric sizes and nearly superparamagnetic behavior. The Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} and CaFe{sub 2}O{sub 4} ferrites presented a size within the range of 12–14 nm and appropriate heating ability for hyperthermia applications. Hemolysis testing demonstrated that Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} ferrite was not cytotoxic when using 10 mg of ferrite/mL of solution. According to the results obtained, Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} is a potential material for cancer treatment by magnetic hyperthermia therapy. - Highlights: • The synthesis of Zn{sub (1−x)}Ca{sub x}Fe{sub 2}O{sub 4} ferrites was performed by sol-gel method. • CaFe{sub 2}O{sub 4} and Zn{sub 0.50}Ca{sub 0.}50Fe{sub 2}O{sub 4} ferrites showed heating ability. • The Zn{sub 0.50}Ca{sub 0.50}Fe{sub 2}O{sub 4} ferrite demonstrated to be no hemolytic.

Preparation, microstructure and magnetic properties of Sm(Co,Hf){sub 7}/Co nanocomposite particles by polyol method

Energy Technology Data Exchange (ETDEWEB)

Bu, Shao-Jing; Duan, Xiu-Li; Han, Xu-Hao; Sun, Ji-Bing, E-mail: hbgdsjb@126.com; Chi, Xiang; Cui, Chun-Xiang

2017-02-01

Hard/soft Sm-Co/Co nanocomposite particles were prepared by reducing CoCl{sub 2}·6H{sub 2}O in the solution containing ball-milled Sm(Co, Hf){sub 7} particles by a simple polyol method with ethylene glycol as the solvent. Phase composition, microstructure and magnetic properties of the particles were analyzed by XRD, TEM (HRTEM) and VSM, respectively. It has been found that Sm-Co/Co core/shell structure is formed in which the Co shell is 3–5 nm in thickness and mainly exists in hcp-Co phase. At the same time, fcc-Co tends to nucleate and grow independently between Sm-Co particles. The formation mechanism of Sm-Co/Co composite particles is discussed and corresponding model is established. Sm-Co/Co composite particles perform obvious remanence enhancement effects especially after being heated at 450 °C for 15 min.

Hierarchically structured carbon-coated SnO{sub 2}-Fe{sub 3}O{sub 4} microparticles with enhanced lithium storage performance

Energy Technology Data Exchange (ETDEWEB)

Chai, Xiaohan; Shi, Chunsheng [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin, 300072 (China); Liu, Enzuo [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin, 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Li, Jiajun [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin, 300072 (China); Zhao, Naiqin [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin, 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin, 300072 (China); He, Chunnian, E-mail: cnhe08@tju.edu.cn [School of Materials Science and Engineering and Tianjin Key Laboratory of Composites and Functional Materials, Tianjin University, Tianjin, 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072 (China); Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin, 300072 (China)

2016-01-15

Graphical abstract: Hierarchically structured SnO{sub 2}-Fe{sub 3}O{sub 4}@C microparticles for lithium-ion battery anode are developed by a facile and scalable strategy. - Highlights: • Hierarchically structured SnO{sub 2}-Fe{sub 3}O{sub 4}@C micrometer-sized particles were synthesized. • The SnO{sub 2}-Fe{sub 3}O{sub 4}@C micrometer-sized particles deliver high reversible lithium storage capacity. • The wrapped carbon layer can buffer the volume expansion of SnO{sub 2}-Fe{sub 3}O{sub 4}. - Abstract: A facile and scalable strategy was developed to fabricate SnO{sub 2}-Fe{sub 3}O{sub 4}@C micrometer-sized particles as a good lithium-ion battery anode. The obtained materials were constructed by aggregated nanoclusters (100–200 nm) consisting of SnO{sub 2}-Fe{sub 3}O{sub 4}@C nanospheres (20 ∼ 30 nm), in which SnO{sub 2} and Fe{sub 3}O{sub 4} nanoparticles (5 ∼ 8 nm) were homogeneously embedded in a percolating carbonaceous network with an average thickness of about 3 nm. SnO{sub 2}-Fe{sub 3}O{sub 4}@C microparticles were synthesized by a one-pot hydrothermal process followed by annealing under Ar and subsequent chemical vapor transformation (CVT) under vacuum. The peculiar strategy allows to obtain hierarchical structure of micrometer-sized particles including nanospheres, nanoclusters and micro-scale particles, and the combination of SnO{sub 2} and Fe{sub 3}O{sub 4} could promote the synergistic effects to enhance the reversible capacity as well as the structural stability. Meanwhile, the carbon layer, homogeneously covering the nanoparticles does not only accommodate the volume change of active materials to maintain the structural integrity but also forms a conductive network throughout the whole micro-sized structure during charge/discharge processes. As a result, the electrode of SnO{sub 2}-Fe{sub 3}O{sub 4}@C microparticles exhibits good rate performance (1056 mAh g{sup −1} at 0.1 C, 734 mAh g{sup −1} at 0.2 C, 449 mAh g{sup −1} at 0.5 C, 212

Elimination of particle effects in SF/sub 6/ insulated transmission systems. First quarterly report

Energy Technology Data Exchange (ETDEWEB)

Dale, S.J.

1979-01-01

The purpose of this program is to develop methods and equipment to eliminate the adverse effect of particle contamination in SF/sub 6/-insulated transmission (CGIT) systems, so that the excellent dielectric properties of SF/sub 6/ can be fully exploited. Presently, CGIT systems are operated at about 10% of the dielectric strength capability of the SF/sub 6/ gas. The program includes theoretical and experimental evaluation of concepts, optimization and verification studies in CGIT systems, and reliability analysis, documentation of designs and economic analysis. Progress is now being made on evaluating alternative conductor and sheath designs to minimize the effect of particles. Materials for solid insulation is being investigated for the same purpose; the effort is presently concentrated on obtaining reliable quantitative measurement techniques of electrostatic properties. Computer calculation of particle trap configurations are being made to determine the optimum trap configurations. A novel particle trapping technique is being using adhesive materials. Manufacture and field control technique studies has commenced with a study of mechanical vibration techniques. An experimental test chamber consisting of a 9 m (30 foot) long 145 kV bus has been designed. This system will be used in testing of particle control concepts and in migration and optimization studies.

Practical Considerations for Detection and Characterization of Sub-Micron Particles in Protein Solutions by Nanoparticle Tracking Analysis.

Science.gov (United States)

Gruia, Flaviu; Parupudi, Arun; Polozova, Alla

2015-01-01

Nanoparticle Tracking Analysis (NTA) is an emerging analytical technique developed for detection, sizing, and counting of sub-micron particles in liquid media. Its feasibility for use in biopharmaceutical development was evaluated with particle standards and recombinant protein solutions. Measurements of aqueous suspensions of NIST-traceable polystyrene particle standards showed accurate particle concentration detection between 2 × 10(7) and 5 × 10(9) particles/mL. Sizing was accurate for particle standards up to 200 nm. Smaller than nominal value sizes were detected by NTA for the 300-900 nm particles. Measurements of protein solutions showed that NTA performance is solution-specific. Reduced sensitivity, especially in opalescent solutions, was observed. Measurements in such solutions may require sample dilution; however, common sample manipulations, such as dilution and filtration, may result in particle formation. Dilution and filtration case studies are presented to further illustrate such behavior. To benchmark general performance, NTA was compared against asymmetric flow field flow fractionation coupled with multi-angle light scattering (aF4-MALS) and dynamic light scattering, which are other techniques for sub-micron particles. Data shows that all three methods have limitations and may not work equally well under certain conditions. Nevertheless, the ability of NTA to directly detect and count sub-micron particles is a feature not matched by aF4-MALS or dynamic light scattering. Thorough characterization of particulate matter present in protein therapeutics is limited by the lack of analytical methods for particles in the sub-micron size range. Emerging techniques are being developed to bridge this analytical gap. In this study, Nanoparticle Tracking Analysis is evaluated as a potential tool for biologics development. Our results indicate that method performance is molecule-specific and may not work as well under all solution conditions, especially when

Effects of nano-SiO{sub 2} particles on surface tracking characteristics of silicone rubber composites

Energy Technology Data Exchange (ETDEWEB)

Liu, Yong, E-mail: tjuliuyong@tju.edu.cn; Li, Zhonglei; Du, Boxue [Key Laboratory of Smart Grid of Ministry of Education (Tianjin University), School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072 (China)

2014-09-08

Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO{sub 2} particles at weight ratios from 0.1 to 1.0 wt. % exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO{sub 2} particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO{sub 2} particles, however, (above 0.3 wt. %) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistance to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO{sub 2} particles, especially at an optimal weight ratio (0.1 to 0.3 wt. %), may have significant potential applications as outdoor insulators for power systems.

Improvement of tribological properties of magnetic tape by silica coating onto the Co-{gamma}-Fe{sub 2}O{sub 3} fine particles; Kobaruto hichakugata {gamma}-Fe{sub 2}O{sub 3} jisei biryushi no shisshiki shirika hyomen shori ni yoru jikitepu no suberi tokusei no kaizen

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Kazuyuki; Iwasaki, Keisuke; Tanaka, Yasuyuki; Morii, Hiroko [Toda Kogyo Corporation, Hiroshima (Japan). R and D Center

1999-01-10

In order to improve the tribological properties of magnetic tape with Co-{gamma}-Fe{sub 2}O{sub 3} fine particles against a magnetic head, the silica coating onto the surface of Co-{gamma}-Fe{sub 2}O{sub 3} particles in aqueous slurry is investigated experimentally, and the kinetic friction coefficient of magnetic tapes prepared using the coated particles is measured. By this silica coating, the amount of myristic acid absorbed on the Co-{gamma}-Fe{sub 2}O{sub 3} particles tends to decrease and the kinetic friction coefficient of the magnetic tapes can be reduced from 0.4 to 0.2 because of the increase of the effective amount of myristic acid working as the lubricant when the magnetic tape is moving. Since the magnetic properties and the dispersibility of Co-{gamma}-Fe{sub 2}O{sub 3} pigment in the magnetic lacquer are not degraded by the silica coating, this coating method is expected to result in magnetic recording media with both good magnetic and low friction properties. (author)

Effects of the virtual particle number on the S matrix of the (phi4)/sub 1+1/ model

International Nuclear Information System (INIS)

Kroeger, H.; Girard, R.; Dufour, G.

1987-01-01

We present results of the S matrix in the (phi 4 )/sub 1 + 1/ model obtained by a nonperturbative calculation using a momentum-space discretization technique. First, we calculate the two-body S matrix in the strong-coupling regime (up to λ/sub eff/ = 3), with the restriction of taking into account only two-body virtual particle states. We find agreement with standard perturbation theory obtained by summing up the corresponding graphs to infinite order. We also estimate the effect of mass renormalization. Second, we investigate the effect of including higher virtual particle numbers in two-particle scattering in the cases λ/sub eff/ = (1/6) and λ/sub eff/ = 1. In both cases we find convergence of the S matrix with respect to increasing the virtual-particle-number cutoff

Prospects of particle physics

International Nuclear Information System (INIS)

Meyer-Berkhout, U.

1986-01-01

Remarkable progress has been achieved in the last two decades in the field of particle physics. From the insight gained by the many experimental data, physicists derive a framework picture of matter on the sub-nuclear level, consisting of fundamental components which interact with each other in a defined and quantitatively detectable manner. The data now available allowed a quantum field theory of strong interactions to be set up for the first time, and a unified theory of electromagnetic and weak interaction. Particle physicists today take particular interest in the problem of whether the strong interaction might fit into an extended unified theory. Such a grand unified theory would have a far-reaching impact on the conceptual models both of the cosmic and sub-nuclear dimensions, and possibly lead to observable effects in domains of energy and mass which will be opened up for experiments by the new accelerator generation underway. Current activities throughout the world for constructing or projecting the new high-energy particle accelerators are outlined in the article, together with the prospects expected by particle physicists, and a look back on the history and achievements of this field of science. (orig.) [de

Electron sub-cycling in particle simulation of plasma

International Nuclear Information System (INIS)

Adam, J.C.; Serveniere, A.G.; Langdon, A.B.

1982-01-01

A straightforward modification which reduces by half the computational cost of standard particle-in-cell algorithms for simulation of plasmas is described. The saving is obtained by integrating only the electrons through a number of time steps (sub-cycle) in order to resolve their evolution, while integrating the much slower ions only once per cycle, i.e., to match the time step of each species to their characteristic frequencies. A dispersion relation is derived which describes the numerical instabilities expected by sampling frequency arguments. Simulations support the broad features of the analytical results, viz., the maximum growth rate and domain of the instability, and its stabilization by the addition of weak damping. An implicit sub-cycling algorithm is suggested which may provide further saving while avoiding a limitation of implicit algorithms described elsewhere

Spontaneous growth of whiskers from an interlayer of Mo sub 2 C beneath a diamond particle deposited in a combustion-flame

Energy Technology Data Exchange (ETDEWEB)

Okada, Katsuyuki; Komatsu, Shojiro; Ishigaki, Takamasa; Matsumoto, Seiichiro; Moriyoshi, Yusuke (National Inst. for Research in Inorganic Materials, Tsukuba, Ibaraki (Japan))

1992-02-01

When diamond particles deposited on a molybdenum substrate in a C{sub 2}H{sub -}O{sub 2} combustion-flame were kept for one year in the ambient atmosphere at room temperature, spontaneous whisker growth from an interlayer of Mo{sub 2}C beneath the diamond particles took place. The whiskers were clarified by electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM) in a polycrystal composed of MoO{sub 2}, MoOC, and Mo{sub 2}C. The growth mechanism of them is discussed from two different points of view as follows: One is that the oxidation of an interlayer of Mo{sub 2}C beneath a diamond particle effectively reduces the surface free energy between the interlayer and diamond particle; consequently, the whisker can grow by using a screw dislocation. The other is that the internal stress existing between a diamond particle and an Mo{sub 2}C interlayer provides a very reactive zone where the growth of whisker takes place through the oxidation of Mo{sub 2}C. (orig.).

Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe{sub 3}O{sub 4} particles

Energy Technology Data Exchange (ETDEWEB)

Calvo, S. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Arias, N.P. [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Departamento de Ingenieria Electrica, Electronica y Computacion, Facultad de Ingenieria y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Giraldo, O., E-mail: ohggiraldo@hotmail.com [Laboratorio de Materiales Nanoestructurados y Funcionales, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Rosales-Rivera, A.; Moscoso, O. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia)

2012-08-15

Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe{sup 2+} and Fe{sup 3+}in NaOH or NH{sub 4}OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 Degree-Sign C and 800 Degree-Sign C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

Preparation of spherical and cubic Fe{sub 55}Co{sub 45} microstructures for studying the role of particle morphology in magnetorheological suspensions

Energy Technology Data Exchange (ETDEWEB)

Arief, Injamamul; Mukhopadhyay, P.K., E-mail: pkm@bose.res.in

2014-06-01

Cubic and spherical Fe{sub 55}Co{sub 45} alloyed microstructures were synthesized by borohydride reduction from aqueous solutions of metallic precursors, using stabilizers and polymer. Monosodium citrate, sodium acetate and PEG 6000 were utilized as electrostatic stabilizers and polymeric surface modifier. Suitable reaction conditions were maintained for synthesis of predominantly larger particles (0.7 µm to 1.2 µm), that facilitates use in magnetorheological fluids. Surface morphological studies by scanning electron microscopy revealed well shaped cubic and spherical geometry for the citrate and polymer-stabilized Fe{sub 55}Co{sub 45} alloys, while the alloy compositions remained nearly the same for both. X-ray diffractions of the as-prepared and annealed samples under various temperatures showed high degree of crystallinity with increasing temperatures. Studies of D.C. magnetization of the systems reveal that the particles have a core–shell structure, with inner magnetic core having a diameter around 30 nm with a log-normal distribution. Magnetorheological studies were performed with 8 vol% suspensions of as-synthesized particles dispersed in silicone oil (viscosity 30 mPa s at 25 °C) under different magnetic fields. Detailed studies of the magnetorheological properties were studied on these systems for practical use.

Optically induced second-harmonic generation in CdI sub 2 -Cu layered nanocrystals

CERN Document Server

Voolless, F; Hydaradjan, W

2003-01-01

A large enhancement (up to 0.40 pm V sup - sup 1) of the second-order optical susceptibility was observed in CdI sub 2 -Cu single-layered nanocrystals for the Nd:YAG fundamental laser beam lambda = 1.06 mu m. The Cu impurity content and nanolayer thickness of the cleaved layers (about several nanometres) play a crucial role in the observed effect. The temperature dependence of the optical second-harmonic generation (SHG) together with its correlation with Raman spectra of low-frequency modes indicate a key role for the UV-induced anharmonic electron-phonon interactions in the observed effect. The maximal output UV-induced SHG was achieved for a Cu content of about 0.5% and at liquid helium temperatures.

Structural, magnetic and optical characterization of Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} nano particles prepared by co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Kannan, Y.B., E-mail: ybkans@gmail.com [Department of Physics, Arumugam Pillai Seethai Ammal College, Tiruppattur 630211 (India); Saravanan, R. [Research Centre & PG Department of Physics, The Madura College, Madurai 625011 (India); Srinivasan, N. [Research Centre & PG Department of Physics, Thiagarajar College, Madurai 625009 (India); Praveena, K. [School of Physics, Univeristy of Hyderabad, Hyderabad 500046 (India); Sadhana, K. [Material Research Center, Indian Institute of Science, Bangalore 560012 (India)

2016-12-01

Bond strength values, between tetrahedral sites and octahedral sites atoms in the unit cell, are evaluated using maximum entropy method (MEM) for the Ni{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} nano ferrite particles, prepared by co-precipitation method and sintered at 900 °C. The spinel structure is confirmed from the XRD analysis done using the Rietveld method. Substitution of zinc ion causes increase in lattice parameter value. Thermal behavior, morphology, magnetic properties and optical band gap energy values of the sample are determined by using thermogravimetric analysis and differential thermal analysis, scanning electron microscope, vibrating sample magnetometer and UV–VIS–NIR techniques respectively. Low value of saturation magnetization is attributed to the disorder in cation distribution.

Oxidation of nickel particles in an environmental TEM

DEFF Research Database (Denmark)

Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

nanometres in size. These domains impinge and cover the particles surface. As the temperature increases under O2, the NiO film grows and creates irregular structures composed of many crystallites. The reaction kinetics are inferred by EELS using different techniques analyzing changes in shapes of the Ni L2...... temperature, providing new insights into oxidation/corrosion processes....

The Formation of Lithiated Ti-Doped {alpha}-Fe{sub 2}O{sub 3} Nanocrystalline Particles by Mechanical Milling of Ti-Doped Lithium Spinel Ferrite

Energy Technology Data Exchange (ETDEWEB)

Widatallah, H. M., E-mail: hisham@ictp.trieste.it [Khartoum University, Department of Physics (Sudan); Gismelseed, A. M.; Bouziane, K. [Sultan Qaboos University, Department of Physics (Oman); Berry, F. J. [Open University, Department of Chemistry (United Kingdom); Al Rawas, A. D.; Al-Omari, I. A.; Yousif, A. A.; Elzain, M. E. [Sultan Qaboos University, Department of Physics (Oman)

2004-12-15

The milling of spinel-related Ti-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} for different times is studied with XRD, Moessbauer spectroscopy and magnetic measurements. Milling converts the material to Li-Ti-doped {alpha}-Fe{sub 2}O{sub 3} nanocrystalline particles via an intermediate {gamma}-LiFeO{sub 2}-related phase. The role played by the dopant Ti-ion in the process is emphasized.

Fabrication of Al-based composites reinforced with in situ devitrified Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles by hot pressing consolidation

Energy Technology Data Exchange (ETDEWEB)

Yang, Qing, E-mail: buaayq00@gmail.com; Zhang, Yitan; Zhang, Haiping; Zheng, Ruixiao; Xiao, Wenlong; Ma, Chaoli, E-mail: machaoli@buaa.edu.cn

2015-11-05

In this study, Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles reinforced Al-based composites were prepared by hot pressing sintering and subsequent hot extrusion. The glassy powders were produced by gas atomization and then employed to mechanical milling. After hot pressing sintering, the nano-scale intermetallic compounds precipitated from metallic glass matrix due to higher temperature than super-cooled liquid region. The mechanical properties of 2024 alloy were improved by addition of glassy particles. The ultimate compressive stress increased from 482 MPa for 2024 alloy to 545 MPa, 627 MPa and 735 MPa for composites with 20 w.t.% 40 w.t.% and 60 w.t.% glassy powders addition, respectively, together with considerable fracture strain ranging between 2.9% and 13.6%. And the mechanical properties could be predicted by using the Rule of Mixture, which predicts the mechanical properties of the bulks from the volume weighed average of the constituent properties. - Highlights: • The composites are fabricate by hot pressing and extrusion. • The single phase of amorphous alloy is obtained by sieving. • The nano-scale compounds precipitates from glassy matrix. • The compressive strength reaches to the value of 735 MPa. • The strength can fit well with rule of mixture.

Fabrication and electromagnetic properties of flake ferrite particles based on diatomite

Energy Technology Data Exchange (ETDEWEB)

Zhang Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang Wenqiang, E-mail: zwqzwqzwqzwq@126.com [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Cai Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

2011-09-15

Hexagonal ferrite BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} coated surfaces of diatomite flakes of low density were synthesized by a sol-gel method. The phase structures, morphologies, particle size and chemical compositions of the composites were characterized by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The results show that hexagonal ferrite coated diatomite flakes can be achieved, and that the coating consisted of BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. The vibranting sample magnetometer results reveal that the flake ferrite particles have static magnetic properties. The complex permeability and permittivity of the composites were measured in the frequency range of 1-18 GHz. The microwave absorption properties of these ferrite particles are discussed. The results indicate that the flake ferrites have the potential to be used as a lightweight broad band microwave absorber. - Highlights: > We synthesize the flake ferrite particles using diatomite as a template. > Flake ferrite particles' coating layers are constituted by BaZn{sub 1.1}Co{sub 0.9}Fe{sub 16}O{sub 27} nanoparticles. > Flake ferrite particles have good static magnetic properties. > Flake ferrites are a kind lightweight broad band microwave absorber.

Compressive strain-dependent bending strength property of Al{sub 2}O{sub 3}-ZrO{sub 2} (1.5 mol% Y{sub 2}O{sub 3}) composites performance by HIP

Energy Technology Data Exchange (ETDEWEB)

Reyes-Rojas, A. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico)], E-mail: armando_reyesmx@yahoo.com.mx; Esparza-Ponce, H. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico); De la Torre, S.D. [Centro de Investigacion e Innovacion Tecnologica (CIITEC)-IPN, D.F. Mexico (Mexico); Torres-Moye, E. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico)

2009-04-15

Nanometric powders and sintered ceramics of Al{sub 2}O{sub 3}-ZrO{sub 2} (1.5 mol% Y{sub 2}O{sub 3}) prepared by hot isostatic pressing HIP have been studied. A detailed crystallographic study has been performed through X-ray diffraction, Williamson-Hall method, Rietveld method and high-resolution electron microscopy HREM analysis. The crystallographic structure data, such as domain size, lattice parameters, wt% phase, and micro-strain direction have been obtained using Rietveld refinement and Williamson-Hall methods. The results revealed that the compressive strain ({epsilon}) increased from 0.56 to 1.18 (10{sup -3}) as the t-ZrO{sub 2} content increased too. The HREM interface study conducted along the [0 0 0 1]Al{sub 2}O{sub 3}||[0 0 1]ZrO{sub 2} zone axis revealed a micro-strain lattice distortion accumulated at the grain boundary due to the ZrO{sub 2} martensitic phase transformation on cooling, t-ZrO{sub 2} grains coalescence and to the grain growth of {alpha}-Al{sub 2}O{sub 3} which cause elongated tetragonal crystals. Micro-strain lattice distortion is adjusted by the shear displacements of the planes (1 1 0) and (11-bar0) along [1-bar10] and [1-bar1-bar0] crystallographic directions, respectively; these planes are arrested by the (101-bar0) alumina plane. In this case, semi-coherent interfaces were observed along the grain boundary. It is verified that the bending strength increased in connection with the strain accumulation and amount of tetragonal structure.

Magnetic resonance and antiresonance in microwave transmission through nanocomposites with Fe{sub 3}Ni{sub 2} and FeNi{sub 3} particles

Energy Technology Data Exchange (ETDEWEB)

Rinkevich, A.B. [M.N. Miheev Institute of Metal Physics Ural Branch of RAS, 18 S.Kovalevskaya St, Ekaterinburg 620990 (Russian Federation); Samoylovich, M.I. [OAO TsNITI “TEKHNOMASH”, 4 Ivana Franko St, Moscow 121108 (Russian Federation); Nemytova, O.V., E-mail: mif-83@mail.ru [M.N. Miheev Institute of Metal Physics Ural Branch of RAS, 18 S.Kovalevskaya St, Ekaterinburg 620990 (Russian Federation); Kuznetsov, E.A. [Nizhny Tagil branch of the Ekaterinburg state social-pedagogical university, 57 Krasnogvardeyskaya St, Nizhny Tagil 622031 (Russian Federation)

2017-06-15

Investigation of magnetic properties and microwave resonance phenomena in nanocomposites based on opal matrices containing the particles of intermetallide of Fe{sub 3}Ni{sub 2} and FeNi{sub 3} is carried out. The interactions which lead to the resonance changes of transmission and reflection coefficients are determined. Electromagnetic properties are measured in the millimeter frequency range. Special attention is paid to comparison between static and dynamic magnetic properties of nanocomposites. Frequency dependences of magnitude of lines of resonance features are obtained. Spectra of resonance and antiresonance are studied. The conditions when the magnetic antiresonance is observed are clarified. The X-ray phase analysis of the nanocomposites is performed and their structure is studied.

Energy-loss straggling study of proton and alpha-particle beams incident onto ZrO{sub 2} and Al{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Behar, M.; Fadanelli, R.C. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970 (Brazil); Abril, I. [Departamento de Fisica Aplicada, Universitat d' Alacant, 03080 Alacant (Spain); Garcia-Molina, R. [Departamento de Fisica, Centro de Investigacion en Optica y Nanofisica, Universidad de Murcia, 30100 Murcia (Spain); Nagamine, L.C.C. [Instituto de Fisica, Universidade de Sao Paulo, C.P.66318, 05315-970 Sao Paulo (Brazil)

2011-10-15

The energy-loss straggling of zirconia (ZrO{sub 2}) and alumina (Al{sub 2}O{sub 3}) has been experimentally determined for proton and alpha-particle beams mainly by means of the Rutherford backscattering technique and in some few cases using the transmission method. The incident energies of the projectiles covers a wide range, from 200 keV up to 2000 keV for H{sup +} and from 200 keV up to 4000 keV for He{sup +} in zirconia films. In the case of alumina films the studied energy range was 100 keV - 3000 keV for H{sup +} and 100 keV - 6000 keV for He{sup +}. Our experimental results compare very well with theoretical calculations based on the dielectric formalism and a suitable description of the electronic excitation spectrum of ZrO{sub 2} and Al{sub 2}O{sub 3} films through their energy-loss function. (authors)

Sub-doppler spectroscopy based on the transit relaxation of atomic particles in a thin gas cell

International Nuclear Information System (INIS)

Azad, Izmailov

2011-01-01

This paper is the review of methods, achievements, and possibilities of the recently elaborated high-resolution laser spectroscopy based on sub-doppler absorption, fluorescence and polarization resonances (on centers of quantum transitions), which arise because of the specific optical selection of comparatively slow-speed atoms or molecules in a thin cell with a rarefied gas. It is considered two following mechanisms of such velocity selection of atomic particles connected with their flight durations between walls of the thin cell : 1) optical pumping of sublevels of the ground atomic term and 2) optical excitation of long-lived metastable quantum levels. Theoretical bases of elaborated spectroscopy methods are presented. In case of the optical pumping mechanism, experimental technique and results on the record of sub-doppler spectral structure of Cs and Rb atoms and on the frequency stabilization of diode lasers by given methods are described. Perspectives of further development and applications of this new direction of the high-resolution spectroscopy are discussed

Sub-doppler spectroscopy based on the transit relaxation of atomic particles in a thin gas cell

International Nuclear Information System (INIS)

Izmailov, Azad

2010-01-01

This paper is the review of methods, achievements and possibilities of the recently elaborated high-resolution laser spectroscopy based on sub-doppler absorption, fluorescence and polarization resonances, which arise because of the specific optical selection of comparatively slow-speed atoms in a thin cell with rarefied gas. It was considered two following mechanisms of such a velocity selection of atomic particles connected with their flight durations between walls of the thin cell : 1) optical pumping of sublevels of the ground atomic term and 2) optical excitation of long-lived quantum levels. Theoretical bases of elaborated spectroscopy methods are presented. In case of the optical pumping mechanism, experimental technique and results on the record of sub-doppler spectral structure of Cs and Rb atoms and on the frequency stabilization of diode lasers by given methods are described. Perspectives of further development and applications of this new direction of the high-resolution spectroscopy are discussed

Synthesis of SrCo {sub x} Ti {sub x} Fe{sub (12-2{sub x})}O{sub 19} through sol-gel auto-ignition and its characterisation

Energy Technology Data Exchange (ETDEWEB)

Thompson, Simon [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom); Shirtcliffe, Neil J. [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom)]. E-mail: neil.shirtcliffe@ntu.ac.uk; O' Keefe, Eoin S. [QinetiQ, Farnborough, Hampshire (United Kingdom); Appleton, Steve [QinetiQ, Farnborough, Hampshire (United Kingdom); Perry, Carole C. [Chemistry and Physics, Nottingham Trent University, Clifton Lane, Clifton, Nottingham, NG11 8NS (United Kingdom)]. E-mail: carole.perry@ntu.ac.uk

2005-04-15

Cobalt-titanium-doped strontium hexaferrites SrCo {sub x} Ti {sub x} Fe{sub (12-2{sub x})}O{sub 19} were synthesised via a sol-gel route using two different complexing agents (ethylene glycol and citric acid). Both routes led to quite pure undoped Sr ferrites, but the citric acid route formed purer doped materials. All synthesised materials consisted of particles smaller than 1 {mu}m, which is the size of a single magnetic domain, and various doping levels were achieved with the final elemental composition being within the bounds of experimental error. The materials synthesised using citric acid were compared with materials synthesised by a solid-state route using ferromagnetic resonance measurements and they were identical within experimental error. Citrate auto-ignition synthesis is more rapid and less prone to contamination than the standard solid-state method and doping levels can be easily varied between runs.

Effect of nano-TiO{sub 2} particles size on the corrosion resistance of alkyd coating

Energy Technology Data Exchange (ETDEWEB)

Deyab, M.A., E-mail: hamadadeiab@yahoo.com; Keera, S.T.

2014-08-01

The coating system containing various sizes (∼10, 50, 100, 150 nm) of nano-TiO{sub 2} were prepared and investigated for corrosion protection of carbon steel in 1.0 M H{sub 2}SO{sub 4} using polarization, EIS and transmission electron microscopy (TEM) techniques. It was found that nano-TiO{sub 2} particles improved the corrosion resistance of alkyd coatings. The corrosion resistance occurs via physical adhesion on the metal surface. O{sub 2} and H{sub 2}O permeability of coating decreased with decrease in the nano-TiO{sub 2} size. The inhibition efficiency was found to increase with decreasing the size of nano-TiO{sub 2} and with decreasing the temperature. - Highlights: • Nano-TiO{sub 2} coating were prepared and used for corrosion protection of C-steel. • Nano-TiO{sub 2} particles in coating are effective to improve the corrosion resistance. • Nano-TiO{sub 2} coating inhibit both anodic and cathodic reactions. • Corrosion inhibition efficiency increases with decrease in the size of nano-TiO{sub 2}. • O{sub 2} and H{sub 2}O permeability of coating decreased with decrease in the nano-TiO{sub 2} size.

Transparent La{sub 2−x}Gd{sub x}Zr{sub 2}O{sub 7} ceramics obtained by combustion method and vacuum sintering

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhengjuan [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhou, Guohong, E-mail: sic_zhough@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Qin, Xianpeng; Yang, Yan [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Guangjun [SCHOTT Glass Technologies (Suzhou) Co. Ltd., Suzhou 215009 (China); Menke, Yvonne [Schott AG, Corporate Research and Technology Development, Hattenbergstrasse 10, 55122 Mainz (Germany); Wang, Shiwei, E-mail: swwang51@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2014-02-05

Highlights: • Combustion method and vacuum sintering were used to fabricate La{sub 2-x}Gd{sub x}Zr{sub 2}O{sub 7}. • The lattice parameters decreased with the increase of Gd{sup 3+} concent(x). • The absorption edge of the transmittance curves shifted to UV region from 0.4-2.0. • All the ceramics have high n (2.08), making them candidate for optical lens. • With the increase of x, the effective atomic number and density increased. -- Abstract: Transparent La{sub 2−x}Gd{sub x}Zr{sub 2}O{sub 7} (x = 0–2.0) ceramics were prepared via vacuum sintering from nanometric powders synthesized by a simple combustion method. The changes of phase composition, morphology and in-line transmittance of the resulting ceramics with Gd{sup 3+} content’s variation were investigated. With the increase of Gd{sup 3+} content, the samples keep the pyrochlore structure, but the X-ray diffraction peaks of the powders and ceramics shift to higher angle as the lattice parameters become smaller. All the ceramics are transparent with high in-line transmittance and high refractive index (2.08 @ 632.8 nm, x = 0.4–1.6). These results indicate that La{sub 2−x}Gd{sub x}Zr{sub 2}O{sub 7} ceramics might be used as optical lens. Moreover, with the increase of Gd{sup 3+} content, the effective atomic number and density of the ceramics increase, therefore making them promising host candidates for scintillators.

Structure and phase transition of BiFeO{sub 3} cubic micro-particles prepared by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Zhou, Jian-Ping, E-mail: zhoujp@snnu.edu.cn [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Yang, Ruo-Lin; Xiao, Rui-Juan; Chen, Xiao-Ming [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062 (China); Deng, Chao-Yong [Department of Electronic Science, Guizhou University, Guizhou Guiyang 550025 (China)

2012-11-15

Graphical abstract: Bismuth ferrite (BiFeO{sub 3}) cubic micro-particles with smooth surfaces were synthesized. BiFeO{sub 3} has a hexagonal perovskite structure with a space group R3c below 370 °C and rhombohedral perovskite structure with a space group R3m below 755 °C, undergoes a phase transition in the temperature range of 755–817 °C to a cubic structure, then decompose to liquid and Fe{sub 2}O{sub 3} above 939 °C. Highlights: ► BiFeO{sub 3} micro-particles with smooth surface were synthesized by hydrothermal method. ► BiFeO{sub 3} enjoys hexagonal structure with well element ratio and chemical valence. ► BiFeO{sub 3} transition from rhombohedral phase to cubic phase lasts 60 °C. -- Abstract: Single-phase bismuth ferrite (BiFeO{sub 3}) powders were synthesized with a hydrothermal method by controlling the experimental conditions carefully. The powder structure, morphology and composition were characterized by using X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscope, Raman measurement and X-ray photoelectron spectroscopy. The particles change from irregular agglomerations to regular cubes with increasing KOH concentration. The large BiFeO{sub 3} cubic particles enjoy much smooth surfaces with well-matched element ratio (Bi:Fe:O = 1:1:3) and chemical valence (Bi{sup 3+}, Fe{sup 3+} and O{sup 2−}). The high temperature XRD and differential scanning calorimetry show that BiFeO{sub 3} powders have a hexagonal perovskite structure with a space group R3c below 370 °C and a rhombohedral structure with a space group R3m below 755 °C. BiFeO{sub 3} undergoes a phase transition in the temperature range of 755–817 °C from rhombohedral structure to a cubic phase, then decomposes to liquid and Fe{sub 2}O{sub 3} above 939 °C.

Effect of different sulphur precursors on morphology and band-gap on the formation of Cu{sub 2}ZnSnS{sub 4} (CZTS) particles with microwave irradiation

Energy Technology Data Exchange (ETDEWEB)

Patro, Bharati; Vijaylakshmi, S., E-mail: vlakshmi@iitb.ac.in [Centre for Research in Nanotechnology and Sciences, Indian Institute of Technology Bombay (India); Sharma, Pratibha [Department of Energy Sciences and Engineering, Indian Institute of Technology Bombay (India)

2016-05-23

Cu{sub 2}ZnSnS{sub 4} (CZTS) is a promising semiconductor material for ecological cost effective thin film Photovoltaic (PV) devices. As it contains earth abundant and non-toxic elements, it has the advantages over commercially available CIGS and CdTe thin film PV devices. In the present work, the pure phase Cu{sub 2}ZnSnS{sub 4} particles were successfully synthesised with microwave irradiation. The morphology and phase study was carried out for the samples prepared with two different sulphur precursors viz. thiourea and thioacetamide (TAA). CZTS particles with thiourea as sulphur precursor are more crystalline than CZTS particles with TAA. The band gap of 1.654 eV and 1.713 eV were calculated for the samples prepared with thiourea and TAA respectively.

Morphological and magnetic properties of the hydrothermally prepared α-Fe{sub 2}O{sub 3} nanorods

Energy Technology Data Exchange (ETDEWEB)

Hadia, N.M.A., E-mail: nomery_abass@science.sohag.edu.eg [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo, 33006 Oviedo (Spain); Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); García-Granda, Santiago; García, José R. [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, Universidad de Oviedo, 33006 Oviedo (Spain); Martínez-Blanco, D. [Servicios Científico-Técnicos, Universidad de Oviedo, 33006 Oviedo (Spain); Mohamed, S.H. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt)

2014-10-15

α-Fe{sub 2}O{sub 3} nanorods were synthesized via hydrothermal method. X-ray powder diffraction revealed the formation of rhombohedral α-Fe{sub 2}O{sub 3} single crystal phase with fiber texture. Scanning and transmission electron micrographs analyses showed that the rhombohedral α-Fe{sub 2}O{sub 3} has nanorods in shape with diameters of 40–85 nm and lengths of 150–45,000 nm. Isothermal magnetization vs. applied magnetic field curves measured at room and liquid nitrogen temperatures displayed a variation on magnetic ordering: from weak ferromagnetism at room temperature to not hysteretic behavior at liquid nitrogen temperature that is well described by a Langevin function. Moreover, the zero field cooling-field cooling curves under applied magnetic field of 100 Oe confirms the decreasing of Morin temperature transition due to nanometric size of the samples. - Highlights: • The structural and magnetic properties of α-Fe{sub 2}O{sub 3} nanorods are examined. • Rietveld and Harris texture indicated the [001] is preferentially oriented. • The magnetic characterization evidenced the presence of hematite α-Fe{sub 2}O{sub 3}.

Effect of ZrO{sub 2} particle on the performance of micro-arc oxidation coatings on Ti6Al4V

Energy Technology Data Exchange (ETDEWEB)

Li, Hong; Sun, Yezi; Zhang, Jin, E-mail: zhangjin@ustb.edu.cn

2015-07-01

Highlights: • An anti-oxidation TiO{sub 2}/ZrO{sub 2} composite coating on Ti6Al4V alloy was prepared using micro-arc oxidation technology by adding ZrO{sub 2} particles in single phosphoric acid solution. • The composite coating displays excellent anti-oxidation characteristic at 700 °C in the air. • The concentration of ZrO{sub 2} particles not only influences the roughness and thickness of the coating, but the morphologies, phase composition, oxidation resistance and wear resistance. - Abstract: This paper investigates the effect of ZrO{sub 2} particle on the oxidation resistance and wear properties of coatings on a Ti6Al4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations micron ZrO{sub 2} particles were added in phosphate electrolyte and dispersed by magnetic stirring apparatus. The composition of coating was characterized using X-ray diffraction and energy dispersive spectrum, and the morphology was examined using SEM. The high temperature oxidation resistance of the coating sample at 700 °C was investigated. Sliding wear behaviour was tested by a wear tester. The results showed that the coating consisted of ZrTiO{sub 4}, ZrO{sub 2}, TiO{sub 2}. With ZrO{sub 2} particle addition, the ceramic coating's forming time reduced by the current dynamic curve. It was shown that the addition of ZrO{sub 2} particles (3 g/L, 6 g/L) expressed an excellent oxidation resistance at 700 °C and wear resistance.

Sharpening m{sub T2} cusps. The mass determination of semi-invisibly decaying particles from a resonance

Energy Technology Data Exchange (ETDEWEB)

Harland-Lang, Lucian A. [Durham Univ. (United Kingdom). Dept. of Physics; Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Kom, Chun-Hay [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences; Sakurai, Kazuki [King' s College London (United Kingdom). Theoretical Particle Physics and Cosmology Group; Tonini, Marco [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2013-12-15

We revisit mass determination techniques for the minimum symmetric event topology, namely X pair production followed by X{yields}lN, where X and N are unknown particles with the masses to be measured, and N is an invisible particle. We consider separate scenarios, with different initial constraints on the invisible particle momenta, and present a systematic method to identify the kinematically allowed mass regions in the (m{sub N},m{sub X}) plane. These allowed regions exhibit a cusp structure at the true mass point, which is equivalent to the one observed in the m{sub T2} endpoints in certain cases. By considering the boundary of the allowed mass region we systematically define kinematical variables which can be used in measuring the unknown masses, and find a new expression for the m{sub T2} variable as well as its inverse. We explicitly apply our method to the case that X is pair produced from a resonance, and as a case study, we consider the process pp {yields} A {yields} {chi}{sup +}{sub 1}{chi}{sup -}{sub 1}, followed by {chi}{sup {+-}}{sub 1} {yields} l{nu}, in the minimal supersymmetric standard model and show that our method provides a precise measurement of the chargino and sneutrino masses, m{sub X} and m{sub N}, at 14 TeV LHC with 300 fb{sup -1} luminosity.

Nucleation and Nanometric Inhomogeneity in Niobiogermanate Glass: In-Situ Inelastic Light Scattering and TEM Studies

International Nuclear Information System (INIS)

Takahashi, Y; Ihara, R; Fujiwara, T; Osada, M; Masai, H

2011-01-01

We performed in-situ inelastic light scattering measurement in KNbGeO 5 glass with a high nucleation ability during heating in order to elucidate nanocrystallization dynamics. The results of the in-situ measurement and TEM observation revealed that nanometric heterogeneous region (∼1-2 nm) consisting of the Nb-richer phase develops, i.e., K 3 Nb 7 O 19 , at the temperature, in which glassy-supercooled-liquid (SCL) phase-transition occurs, i.e., precursive stage of nanocrystallization. This strongly suggests that evolution of the nanometric Nb-richer phase in the SCL phase corresponds to nucleation in the KNbGeO 5 glass.

Electrodeposition of Fe{sub 3}O{sub 4} layer from solution of Fe{sub 2}(SO{sub 4}){sub 3} with addition ethylene glycol

Energy Technology Data Exchange (ETDEWEB)

Dahlan, Dahyunir, E-mail: dahyunir@yahoo.com; Asrar, Allan [Department of Physics, Andalas University, Limau Manih Padang 25163, West Sumatera (Indonesia)

2016-03-11

The electrodeposition of Fe{sub 3}O{sub 4} layer from the solution Fe{sub 2}(SO{sub 4}){sub 3} with the addition of ethylene glycol on Indium Tin Oxide (ITO) substrate has been performed. The electrodeposition was carried out using a voltage of 5 volts for 120 seconds, with and without the addition of 2% wt ethylene glycol. Significant effects of temperature on the resulting the samples is observed when they are heated at 400 °C. Structural characterization using X-ray diffraction (XRD) shows that all samples produce a layer of Fe{sub 3}O{sub 4} with particle size less than 50 nanometers. The addition of ethylene glycol and the heating of the sample causes a shrinkage in particle size. The scanning electron microscopy (SEM) characterization shows that Fe{sub 3}O{sub 4} layer resulting from the process of electrodeposition of Fe{sub 2}(SO{sub 4}){sub 3} without ethylene glycol, independent of whether the sample is heated or not, is uneven and buildup. Layer produced by the addition of ethylene glycol without heating produces spherical particles. On contrary, when the layer is heated the spherical particles transform to irregularly-shaped particles with smaller size.

Measurements of double differential charged particle emission cross sections and development of a wide range charged particles spectrometer for ten`s MeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Nauchi, Yasushi; Baba, Mamoru; Kiyosumi, Takehide [Tohoku Univ., Sendai (Japan). Faculty of Engineering] [and others

1997-03-01

We measured (n,xp), (n,xd) cross sections of C and Al for En=64.3 MeV neutrons at the {sup 7}Li(p,n) neutron sources facility at TIARA (Takasaki Establishment, JAERI) by using a conventional SSD-NaI telescope placed in the air. They show characteristic energy and angular dependence in high energy regions. In order to extend the measurements to low energy protons and {alpha} particles, a new spectrometer consisting of low pressure gas counters and BaF{sub 2} scintillators is now under development. A low threshold for low energy {alpha} particles will be achieved by using the gas counters. The particle identification over a wide energy range will be achieved by combining the {Delta}E-E method for low energy particles with the pulse shape discrimination (PSD) method of BaF{sub 2} for high energy particles. (author)

Centrality dependence of low-p{sub T} and high-p{sub T} particle production in proton–lead collisions with ATLAS

Energy Technology Data Exchange (ETDEWEB)

Shulga, Evgeny

2016-12-15

Measurements of the centrality dependence of low-p{sub T} and high-p{sub T} particle production in proton-lead collisions at the LHC can provide unique insight into the dynamics of soft and hard scattering processes and the initial state of ultra-relativistic nuclear collisions. Recent results have shown that both soft and hard processes may be significantly influenced by event-to-event fluctuations (variations) in the structure of the proton. In this proceedings, the latest measurements of the centrality dependence of charged particle, and Z boson production with the ATLAS detector at the LHC are used to explore these questions. In particular, the sensitivity of the charged particle pseudorapidity distribution in proton–lead collisions to the choice of centrality variable is discussed. Separately, to address recent measurements of the correlation between the initial-state hard scattering kinematics in dijet events and forward transverse energy in proton-proton collisions will be presented.

Analysis of PM{sub 2.5} particles in atmospheric dust of the MZVM; Analisis de particulas PM{sub 2.5} en polvo atmosferico de la ZMVM

Energy Technology Data Exchange (ETDEWEB)

Aldape U, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2003-01-15

The objectives and scopes of this report are: to determine the places more representative for the installation of four stations of monitoring of small particles to 2.5 micrometers (PM{sub 2.5} ) guided to protect the population's health in the regions indicated by the General Address of Environmental Administration of the Air (DGGM) of the Government of the Federal District (GDF). To select the places to collect PM{sub 2.5} in each one of the regions under study placing each place inside a contiguous cell of 2 x 2 km. To determine the concentration of PM{sub 2.5} in the selected places. To determine the temporary and space behavior of the fine particles in each one of the regions designated in this study. To determine the elementary concentration of some samples of PM{sub 2.5} in the four regions. The execution of this project will contribute to that the installation of the net of monitoring of particles of PM{sub 2.5} is carried out with scientific foundation. (Author)

Dielectric relaxation of glass particles with conductive nano-coatings

Energy Technology Data Exchange (ETDEWEB)

Hussain, Shahid [Applied Technologies Department, QinetiQ Limited, Cody Technology Park, Farnborough, Hampshire, GU14 0LX (United Kingdom)

2009-03-21

This research focuses on the dielectric properties of particles consisting of glass cores with nanometre conductive coatings. The effects of the core glass particle shape (sphere, flake and fibre) and size are investigated for different coating characteristics over the frequency range 0.5-18 GHz. Experimental results for the coated glass particle combinations show the existence of a dielectric loss peak. This feature is associated with interfacial relaxation between the insulating core glass particle and the nanoscale conductive coating. The relaxation mechanism provides enhanced loss that is not observed in conventional solid metal particle composites. The results are fitted to a model, which shows that the relaxation frequency increases with increasing coating conductivity and thickness, with additional parameters identified for further particle optimizations.

What holds paper together: Nanometre scale exploration of bonding between paper fibres

Science.gov (United States)

Schmied, Franz J.; Teichert, Christian; Kappel, Lisbeth; Hirn, Ulrich; Bauer, Wolfgang; Schennach, Robert

2013-01-01

Paper, a man-made material that has been used for hundreds of years, is a network of natural cellulosic fibres. To a large extent, it is the strength of bonding between these individual fibres that controls the strength of paper. Using atomic force microscopy, we explore here the mechanical properties of individual fibre-fibre bonds on the nanometre scale. A single fibre-fibre bond is loaded with a calibrated cantilever statically and dynamically until the bond breaks. Besides the calculation of the total energy input, time dependent processes such as creep and relaxation are studied. Through the nanometre scale investigation of the formerly bonded area, we show that fibrils or fibril bundles play a crucial role in fibre-fibre bonding because they act as bridging elements. With this knowledge, new fabrication routes can be deduced to increase the strength of an ancient product that is in fact an overlooked high-tech material. PMID:23969946

Synergistic effects of F and Fe in co-doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yufei, E-mail: zhang.yu.fei@stu.xjtu.edu.cn; Shen, Huiyuan; Liu, Yanhua, E-mail: yhliu@mail.xjtu.edu.cn [Xi’an Jiaotong University, Department of Building Environment and Services Engineering, School of Human Settlements and Civil Engineering (China)

2016-03-15

TiO{sub 2} photocatalysts co-doped with F and Fe were synthesized by a sol–gel method. Synergistic effects of F and Fe in the co-doped TiO{sub 2} were verified by NH{sub 3} decomposition, X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet–visible (UV–Vis) absorption spectroscopy, and was analyzed by the simulation based on the density functional theory (DFT). The results from NH{sub 3} decomposition confirmed that the cooperation of F and Fe broadened the optical response of TiO{sub 2} to visible light region and also enhanced the photocatalytic activity of TiO{sub 2} under ultraviolet light. XRD patterns, SEM and HRTEM images showed that the co-doped samples were nanometric anatase with an average particle size of 25 nm. Co-doping with F and Fe inhibited the grain growth of TiO{sub 2} from anatase to rutile and resulted in a larger lattice defect. XPS analysis exhibited that the doped F and Fe atoms were into the TiO{sub 2} lattice. UV–Vis absorption spectra showed that its optical absorption edge was moved up to approximately 617 nm and its ultraviolet absorption was also enhanced. The DFT results indicated that the cooperation of Fe 3d and O 2p orbits narrowed the band gap of TiO{sub 2} and F 2p orbit widened the upper valence bands. The synergistic electron density around F and Fe in co-doped TiO{sub 2} was capable to enhance the photo-chemical stability of TiO{sub 2}.

Achieving sub-millimetre precision with a solid-state full-field heterodyning range imaging camera

Science.gov (United States)

Dorrington, A. A.; Cree, M. J.; Payne, A. D.; Conroy, R. M.; Carnegie, D. A.

2007-09-01

We have developed a full-field solid-state range imaging system capable of capturing range and intensity data simultaneously for every pixel in a scene with sub-millimetre range precision. The system is based on indirect time-of-flight measurements by heterodyning intensity-modulated illumination with a gain modulation intensified digital video camera. Sub-millimetre precision to beyond 5 m and 2 mm precision out to 12 m has been achieved. In this paper, we describe the new sub-millimetre class range imaging system in detail, and review the important aspects that have been instrumental in achieving high precision ranging. We also present the results of performance characterization experiments and a method of resolving the range ambiguity problem associated with homodyne and heterodyne ranging systems.

Adsorption of NO{sub 2} on carbon aerosols particles at the low ppb-level

Energy Technology Data Exchange (ETDEWEB)

Kalberer, M.; Ammann, M.; Baltensperger, U.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-09-01

The adsorption of NO{sub 2} at the low ppb-level (3-40 ppb) on carbon aerosol particles was investigated. A sticking coefficient of about 2.10{sup -4} was found, similar to that in previous studies using radioactively labeled {sup 13}NO{sub 2}. (author) 2 figs., 2 refs.

Three-month performance evaluation of the Nanometrics, Inc., Libra Satellite Seismograph System in the northern California Seismic Network

Science.gov (United States)

Oppenheimer, David H.

2000-01-01

In 1999 the Northern California Seismic Network (NCSN) purchased a Libra satellite seismograph system from Nanometrics, Inc to assess whether this technology was a cost-effective and robust replacement for their analog microwave system. The system was purchased subject to it meeting the requirements, criteria and tests described in Appendix A. In early 2000, Nanometrics began delivery of various components of the system, such as the hub and remote satellite dish and mounting hardware, and the NCSN installed and assembled most equipment in advance of the arrival of Nanometrics engineers to facilitate the configuration of the system. The hub was installed in its permanent location, but for logistical reasons the "remote" satellite hardware was initially configured at the NCSN for testing. During the first week of April Nanometrics engineers came to Menlo Park to configure the system and train NCSN staff. The two dishes were aligned with the satellite, and the system was fully operational in 2 days with little problem. Nanometrics engineers spent the remaining 3 days providing hands-on training to NCSN staff in hardware/software operation, configuration, and maintenance. During the second week of April 2000, NCSN staff moved the entire remote system of digitizers, dish assembly, and mounting hardware to Mammoth Lakes, California. The system was reinstalled at the Mammoth Lakes water treatment plant and communications successfully reestablished with the hub via the satellite on 14 April 2000. The system has been in continuous operation since then. This report reviews the performance of the Libra system for the three-month period 20 April 2000 through 20 July 2000. The purpose of the report is to assess whether the system passed the acceptance tests described in Appendix A. We examine all data gaps reported by NCSN "gap list" software and discuss their cause.

Structure and physical properties of the LaBiFe{sub 2}O{sub 6} Perovskite produced by the modified Pechini method

Energy Technology Data Exchange (ETDEWEB)

Palacio, Johny Andrés Jaramillo; Bello, Elixir William Barrera; Landínez-Téllez, David A.; Roa-Rojas, Jairo, E-mail: jroar@unal.edu.com [Grupo de Física de Nuevos Materiales, Universidad Nacional de Colombia, Bogotá DC (Colombia); Cagigas, Julián Andrés Munévar [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut (Switzerland); Arnache, Oscar [Grupo de Estado Sólido, Universidad de Antioquia, Medellín (Colombia)

2017-10-15

In this paper the synthesis of the LaBiFe{sub 2}O{sub 6} material by the modified Pechini method is reported. Structural, morphologic, magnetic and optic experimental studies were performed. Rietveld refinement of x-ray diffraction patterns revealed that LaBiFe{sub 2}O{sub 6} crystallizes in an orthorhombic perovskite structure (space group Pnma, ⧣ 62). Scanning electron microscopy images showed the nanometric feature of grains. X-ray dispersive spectroscopy permitted to infer the obtaining of the LaBiFe{sub 2}O{sub 6} expected stoichiometry. Results of magnetic susceptibility as a function of temperature and field magnetization evidenced mixed ferromagnetism and superparamagnetism behavior at T=300 K. Mössbauer spectroscopy supported the superparamagnetic and ferromagnetic responses as a result of the nanogranular morphology and anisotropy effects. Spectrum of diffuse reflectance suggest that this material behaves as a semiconductor with energy gap E{sub g} =2.13 eV. (author)

Photocatalytic degradation of methylene blue dye using Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles prepared by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Ahmed, M.A., E-mail: abdelhay71@hotmail.com [Chemistry Department, Faculty of Science, Ain-Shams University (Egypt); El-Katori, Emad E.; Gharni, Zarha H. [Chemistry Department, Faculty of Science, King Khaled University (Saudi Arabia)

2013-03-15

Graphical abstract: Photocatalytic degradation of methylene blue dye was successfully carried over Fe{sub 2}O{sub 3}/TiO{sub 2} nanorods embedded various proportion of Fe{sub 2}O{sub 3} (0–20) wt.%. Highlights: ► Fe{sub 2}O{sub 3}/TiO{sub 2} nano mixed oxide samples were successfully synthesized by sol–gel method. ► Manipulation of particle size and structure were achieved by micelle template approach. ► Both adsorption and photocatalytic reactivity are the main reasons for exceptional decolorization of methylene blue dye. ► A new mechanism for electronic transition between TiO{sub 2} and Fe{sub 2}O{sub 3} was proposed. -- Abstract: The photocatalytic degradation of methylene blue dye was successfully carried under UV irradiation over Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles embedded various composition of Fe{sub 2}O{sub 3} (0–20) wt.% synthesized by sol–gel process. Structural and textural features of the mixed oxide samples were investigated by X-ray diffraction [XRD], Fourier transformer infra-red [FTIR], Energy dispersive X-ray [EDX], Field emission electron microscope [FESEM] and transmission electron microscope [TEM]. However, the optical features were estimated using UV–Vis spectrophotometer. The results reveal that the incorporation of various Fe{sub 2}O{sub 3} up to 7% is associated by remarkable increase in surface area, reduction of particle size, stabilization of anatase phase, shifting the photoexcitation response of the sample to visible region and exceptional degradation of methylene blue dye. On the other hand, increasing Fe{sub 2}O{sub 3} contents up to 20 wt.% is associated by anatase–rutile transformation, increasing in particle size and remarkable decrease in surface area which are prime factors in reducing the degradation process. The experimental results indicate that Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles having both the advantages of photodegradation–adsorption process which considered a promising new

Y{sub 2}O{sub 3}: Eu{sup 3+}, Tb{sup 3+} spherical particles based anti-reflection and wavelength conversion bi-functional films: Synthesis and application to solar cells

Energy Technology Data Exchange (ETDEWEB)

Miao, Hui [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Ji, Ruonan [School of Physics, Northwest University, Xi’an 710069 (China); Hu, Xiaoyun, E-mail: hxy3275@nwu.edu.cn [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Han, Linzi; Hao, Yuanyuan; Sun, Qian [School of Physics, Northwest University, Xi’an 710069 (China); Zhang, Dekai [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); Fan, Jun [School of Chemical Engineering, Northwest University, Xi’an 710069 (China); Bai, Jintao [School of Physics, Northwest University, Xi’an 710069 (China); National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Northwest University, Xi’an 710069 (China); and others

2015-04-25

Highlights: • Eu{sup 3+} and Tb{sup 3+} co-doped Y{sub 2}O{sub 3} particles were successfully prepared. The as prepared particles can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. • Y{sub 2}O{sub 3} is not only a good photoluminescence host material, but also it has high corrosion resistivity, thermal stability, and transparency from violet to infrared light. Cooperated with SiO{sub 2} sols, it could realize a better anti-reflection property. • As a proof-of-concept application, the as prepared bi-functional films could effectively improve the photoelectric conversion efficiency by 0.23% compared to pure SiO{sub 2} AR coating film and 0.55% compared to glass. - Abstract: In this study, Eu{sup 3+} and Tb{sup 3+} co-doped Y{sub 2}O{sub 3} particles were prepared via the simple, cost-effective urea homogeneous precipitation method without additives. The chosen particles were added in the SiO{sub 2} sols to get anti-reflection (AR) and wavelength conversion bi-functional films. Careful investigations were carried out to find the optimum preparation conditions and proper morphology. SEM images showed that the particle sizes reduced as metal ion/urea ratio decreased. Additionally, the extracted particles turned from sphere to lamellar type when the deionized water, which was used as solvent, reduced to a certain extent. The mechanisms of the morphology formation and diversification were proposed as well. The as prepared materials can convert UV region photos to visible photons between 460 nm and 640 nm, which just matched the spectral response of most solar cells. The spherical sample showed better luminescence performance than the one with lamellar morphology. In addition, the optical transmittance spectra indicated that the films adding spherical particles had better anti-reflective performance, and the best adding amount was 0.08 g. Finally, As a proof-of-concept application

First results of the CERN Resonant Weakly Interacting sub-eV Particle Search (CROWS)

CERN Document Server

Betz, M; Gasior, M; Thumm, M; Rieger, S W

2013-01-01

The CERN Resonant Weakly Interacting sub-eV Particle Search probes the existence of weakly interacting sub-eV particles like axions or hidden sector photons. It is based on the principle of an optical light shining through the wall experiment, adapted to microwaves. Critical aspects of the experiment are electromagnetic shielding, design and operation of low loss cavity resonators, and the detection of weak sinusoidal microwave signals. Lower bounds are set on the coupling constant g=4.5 x 10$^{-8}$ GeV$^{-1}$ for axionlike particles with a mass of m$_a$=7.2 $\\mu$eV. For hidden sector photons, lower bounds are set for the coupling constant $\\chi$=4.1 x 10$^{^-9}$ at a mass of m$\\gamma$=10.8 $\\mu$eV. For the latter we are probing a previously unexplored region in the parameter space.

The TiCl{sub 3} catalyst in NaAlH{sub 4} for hydrogen storage induces grain refinement and impacts on hydrogen vacancy formation

Energy Technology Data Exchange (ETDEWEB)

Singh, S.; Eijt, S.W.H. [Fundamental Aspects of Materials and Energy, Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Delft (Netherlands); Huot, J. [Universite du Quebec a Trois Rivieres, Quebec (Canada); Kockelmann, W.A. [ISIS, Rutherford Appleton Laboratory, Chilton, Oxfordshire (United Kingdom); Wagemaker, M. [Fundamental Aspects of Materials and Energy, Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Delft (Netherlands); Mulder, F.M. [Fundamental Aspects of Materials and Energy, Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Delft (Netherlands)], E-mail: f.m.mulder@tudelft.nl

2007-09-15

TiCl{sub 3} acts as an efficient catalyst for NaAlH{sub 4} (sodium alanate), altering its hydrogen sorption kinetics and reversibility considerably. In order to clarify its role, we performed in situ neutron diffraction experiments on protonated catalysed and uncatalysed NaAlH{sub 4}. The phase transformations were monitored in the first two reaction steps during hydrogen release and in the second step during reloading. Our study for the first time provides clear indications that both Ti{sub x}Al{sub 1-x} and NaCl formed act as grain refiner for Al and NaH, respectively, preventing particle growth. Particle sizes generally stay small upon desorption and reloading of TiCl{sub 3} catalysed NaAlH{sub 4}, while significant particle growth is observed for uncatalysed NaAlH{sub 4}. The small crystallite sizes and observed hydrogen vacancy formation greatly facilitate the mass transfer during loading and unloading. This study underlines the importance of grain refining for achieving reversibility and faster kinetics of the hydrogen sorption processes, with a crucial double role played by the catalyst.

Interparticle interactions of FePt core and Fe{sub 3}O{sub 4} shell in FePt/Fe{sub 3}O{sub 4} magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Akbari, Hossein, E-mail: Akbari.ph@iauardabil.ac.ir [Department of Physics, Ardabil Branch, Islamic Azad University, Ardabil (Iran, Islamic Republic of); Zeynali, Hossein [Department of Physics, Kashan Branch, Islamic Azad University, Kashan (Iran, Islamic Republic of); Bakhshayeshi, Ali [Department of Physics, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

2016-02-22

Monodisperse FePt nanoparticles were successfully synthesized using simple wet chemical method. Fe{sub 3}O{sub 4} was used as a magnetic shell around each FePt nanoparticles. In FePt/Fe{sub 3}O{sub 4} core/shell system, core thickness is 2 nm and shell thickness varies from zero to 2.5 nm. A theoretical model presented to calculate the shell thickness dependence of Coercivity. Presented model is compared with the results from Stoner–Wohlfarth model to interpret the shell thickness dependence of Coercivity in FePt/Fe{sub 3}O{sub 4} core/shell nanoparticles. There is a difference between the results from Stoner–Wohlfarth model and experimental data when the shell thickness increases. In the presented model, the effects of interparticle exchange and random magneto crystalline anisotropy are added to the previous models of magnetization reversal for core/shell nanostructures in order to achieve a better agreement with experimental data. For magnetic shells in FePt/Fe{sub 3}O{sub 4} core/shell, effective coupling between particles increases with increasing shell thickness which leads to Coercivity destruction for stronger couplings. According to the boundary conditions, in the harder regions with higher exchange stiffness, there is small variation in magnetization and so the magnetization modes become more localized. We discussed both localized and non-localized magnetization modes. For non-zero shell thickness, non-localized modes propagate in the soft phase which effects the quality of particle exchange interactions. - Highlights: • Monodisperse FePt nanoparticles were successfully synthesized using simple wet chemical method. • Fe{sub 3}O{sub 4} was used as a magnetic shell around each FePt nanoparticles. • A theoretical model presented to calculate the shell thickness dependence of Coercivity. • Magnetic shells increase effective coupling between particles with increasing shell thickness. • Magnetization modes are more localized in the regions with

Size-dependent properties of YBa sub 2 Cu sub 3 O sub 6 sub + sub x nanopowder

CERN Document Server

Paturi, P; Huhtinen, H; Huhtala, V P; Laiho, R

2003-01-01

YBa sub 2 Cu sub 3 O sub 6 sub + sub x nanopowder, prepared by the citrate sol-gel method, is segregated by sedimentation in ethanol into three size groups with average particle heights of 0.7, 1.6 and 2.3 nm. The structural properties and composition of the powders, investigated by x-ray diffraction, atomic force microscopy, Auger electron spectroscopy and EPR-spectroscopy, show no clear differences, except the size. According to investigations by magnetometry and by non-resonant microwave absorption the as-prepared powder contains weak links which, however, disappear during the segregation. The magnetic susceptibility of the samples decreases with the decreasing particle size, in agreement with the susceptibility values calculated from the London equations for cylindrical particles smaller than the London penetration depth. In all three size groups the critical temperature of superconductivity is 92 K.

Influence of different fuel agents on the combustion synthesis of the nanostructured Li{sub 1.05}Mn{sub 2}O{sub 4} oxide

Energy Technology Data Exchange (ETDEWEB)

Amaral, Fabio A.; Guerra, R.F.; Santana, L.K.; Canobre, S.C., E-mail: fabioamaral@iqufu.ufu.br [Universidade Federal de Uberlandia (LAETE/UFU), MG (Brazil). Inst. de Quimica. Lab. de Armazenamento de Energia e Tratamento de Efluentes

2014-08-15

In this work nanostructured Li{sub 1.05}Mn{sub 2}O{sub 4} oxide was obtained by Solution Combustion Synthesis (SCS) using three different fuel agents in order to obtain a unique phase with a crystalline cubic structure belonging to the F{sub d3m} spatial group. The phase of interest could be obtained, following the order: glycine (at 600 °C for 2 h) ‹ urea (at 750 °C for 2 h) ‹ maleic anhydride (at 750 °C for 4 h), with crystallite size in the range from 4.6 to 9.7 nm (nanometric character) and the unit cell parameter of the calcined samples at 750 °C for 2 h were similar to the JCPDS 35-0782 with cubic structure (a = 8.247 Å). Charge and discharge tests from the samples obtained by glycine fuel (at 750 °C for 4 h) presented the highest experimental specific capacities of 115 mA h g{sup -1} and 92% of retention after 10 cycles. (author)

Particle shape inhomogeneity and plasmon-band broadening of solar-control LaB{sub 6} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Machida, Keisuke; Adachi, Kenji, E-mail: kenji-adachi@ni.smm.co.jp [Ichikawa Research Laboratories, Sumitomo Metal Mining Co., Ltd., Ichikawa 272-8588 (Japan)

2015-07-07

An ensemble inhomogeneity of non-spherical LaB{sub 6} nanoparticles dispersion has been analyzed with Mie theory to account for the observed broad plasmon band. LaB{sub 6} particle shape has been characterized using small-angle X-ray scattering (SAXS) and electron tomography (ET). SAXS scattering intensity is found to vary exponentially with exponent −3.10, indicating the particle shape of disk toward sphere. ET analysis disclosed dually grouped distribution of nanoparticle dispersion; one is large-sized at small aspect ratio and the other is small-sized with scattered high aspect ratio, reflecting the dual fragmentation modes during the milling process. Mie extinction calculations have been integrated for 100 000 particles of varying aspect ratio, which were produced randomly by using the Box-Muller method. The Mie integration method has produced a broad and smooth absorption band expanded towards low energy, in remarkable agreement with experimental profiles by assuming a SAXS- and ET-derived shape distribution, i.e., a majority of disks with a little incorporation of rods and spheres for the ensemble. The analysis envisages a high potential of LaB{sub 6} with further-increased visible transparency and plasmon peak upon controlled particle-shape and its distribution.

Effect of annealing on particle size, microstructure and gas sensing properties of Mn substituted CoFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kumar, E. Ranjith, E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India); Kamzin, A.S. [Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Janani, K. [Department of Physics, Kongunadu Arts and Science College, Coimbatore, Tamil Nadu (India)

2016-11-01

Microstructure, morphological and gas sensor studies of Mn substituted cobalt ferrite nanoparticles synthesized by a simple evaporation method and auto- combustion method. The influence of heat treatment on phase and particle size of spinel ferrite nanoparticles were determined by X-ray diffraction and Mossbauer spectroscopy. The XRD study reveals that the lattice constant and crystallite size of the samples increases with the increase of annealing temperature. Last one was confirmed by Mossbauer data. The lowest size of particles of MnCoFe{sub 2}O{sub 4} (~3 nm) is obtained by auto combustion method. The spherical shaped nanoparticles are recorded by TEM. Furthermore, conductance response of Mn–Co ferrite nanomaterial was measured by exposing the material to reducing gas like liquefied petroleum gas (LPG) which showed a sensor response of ~0.19 at an optimum operating temperature of 250 °C. - Highlights: • ~3 nm sized particles were prepared by auto combustion method. • Mossbauer study was analyzed for different annealed samples. • The size of the particles increased with increasing annealing temperature.

High Temperature Falling Particle Receiver (2012 - 2016) - Final DOE Report

Energy Technology Data Exchange (ETDEWEB)

Ho, Clifford K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-04-15

The objective of this work was to advance falling particle receiver designs for concentrating solar power applications that will enable higher temperatures (>700 °C) and greater power-cycle efficiencies (≥50% thermal-to-electric). Modeling, design, and testing of components in Phases 1 and 2 led to the successful on-sun demonstration in Phase 3 of the world’s first continuously recirculating high-temperature 1 MW<sub>t> falling particle receiver that achieved >700 °C particle outlet temperatures at mass flow rates ranging from 1 – 7 kg/s.

Testable flipped SU(5)xU(1){sub X} models

Energy Technology Data Exchange (ETDEWEB)

Jiang Jing [Institute of Theoretical Science, University of Oregon, Eugene, OR 97403 (United States); Li Tianjun [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States) and Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080 (China) and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)]. E-mail: tjli@physics.rutgers.edu; Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States); Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)

2007-06-11

The little hierarchy between the GUT scale and the string scale may give us some hints that can be tested at the LHC. To achieve string-scale gauge coupling unification, we introduce additional vector-like particles. We require that these vector-like particles be standard, form complete GUT multiplets, and have masses around the TeV scale or close to the string scale. Interestingly, only the flipped SU(5)xU(1){sub X} models can work elegantly. We consider all possible sets of vector-like particles with masses around the TeV scale. And we introduce vector-like particles with masses close to the string scale which can mimic the string-scale threshold corrections. We emphasize that all of these vector-like particles can be obtained in the interesting flipped SU(5)xU(1){sub X} string models from the four-dimensional free fermionic string construction. Assuming the low-energy supersymmetry, high-scale supersymmetry, and split supersymmetry, we show that the string-scale gauge coupling unification can indeed be achieved in the flipped SU(5)xU(1){sub X} models. These models can be tested at the LHC by observing simple sets of vector-like particles at the TeV scale. Moreover, we discuss a simple flipped SU(5)xU(1){sub X} model with string-scale gauge coupling unification and high-scale supersymmetry by introducing only one pair of the vector-like particles at the TeV scale, and we predict the corresponding Higgs boson masses. Also, we briefly comment on the string-scale gauge coupling unification in the model with low-energy supersymmetry by introducing only one pair of the vector-like particles at the intermediate scale. And we briefly comment on the mixings among the SM fermions and the corresponding extra vector-like particles.

Synthesis of Li{sub 2}MnO{sub 3}-stabilized LiCoO{sub 2} cathode material by spray-drying method and its high-voltage performance

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhiguo; Wang, Zhixing, E-mail: zxwang.csu@hotmail.com; Guo, Huajun; Peng, Wenjie; Li, Xinhai

2015-03-25

Highlights: • Li{sub 2}MnO{sub 3} is introduced to stabilize the structure of LiCoO{sub 2} at high voltages. • xLi{sub 2}MnO{sub 3}·(1−x)LiCoO{sub 2} with fine particles prepared by a simple spray-drying method. • The modified sample exhibits enhanced high-voltage electrochemical performance. • Possible kinetic behaviors of the electrode surface are discussed. - Abstract: xLi{sub 2}MnO{sub 3}⋅(1 − x)LiCoO{sub 2} (x = 0, 0.02, 0.05, 0.1) as a cathode material for lithium ion batteries has been prepared by a spray-drying assisted solid-state method. The effects of Li{sub 2}MnO{sub 3} content on crystal structure, morphology, and high-voltage electrochemical performance of LiCoO{sub 2} have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and galvanostatic charge–discharge test. XRD results reveal that all samples have a well-ordered layered structure. SEM and EDS analyses confirm that homogeneous powders with a primary particle size of about 2 μm are observed and the elementals distribute uniformly in the particles. Electrochemical tests demonstrate that the modified samples exhibit obviously enhanced cycling stability in the voltage ranges of 3.0–4.5 V and 3.0–4.6 V, although they deliver somewhat lower discharge capacity. Specifically, 0.02Li{sub 2}MnO{sub 3}⋅0.98LiCoO{sub 2} delivers the initial discharge capacity of 189.0, 216.8 mA h g{sup −1} at 0.1 C in the voltage range of 3.0–4.5 V and 3.0–4.6 V, respectively, and excellent cycling behaviors at 1 C are achieved.

Atomistic aspects of ductile responses of cubic silicon carbide during nanometric cutting.

Science.gov (United States)

Goel, Saurav; Luo, Xichun; Reuben, Robert L; Rashid, Waleed Bin

2011-11-11

Cubic silicon carbide (SiC) is an extremely hard and brittle material having unique blend of material properties which makes it suitable candidate for microelectromechanical systems and nanoelectromechanical systems applications. Although, SiC can be machined in ductile regime at nanoscale through single-point diamond turning process, the root cause of the ductile response of SiC has not been understood yet which impedes significant exploitation of this ceramic material. In this paper, molecular dynamics simulation has been carried out to investigate the atomistic aspects of ductile response of SiC during nanometric cutting process. Simulation results show that cubic SiC undergoes sp3-sp2 order-disorder transition resulting in the formation of SiC-graphene-like substance with a growth rate dependent on the cutting conditions. The disorder transition of SiC causes the ductile response during its nanometric cutting operations. It was further found out that the continuous abrasive action between the diamond tool and SiC causes simultaneous sp3-sp2 order-disorder transition of diamond tool which results in graphitization of diamond and consequent tool wear.

Influence of clay particles on Al{sub 2}O{sub 3} and TiO{sub 2} nanoparticles transport and retention through limestone porous media: measurements and mechanisms

Energy Technology Data Exchange (ETDEWEB)

Bayat, Ali Esfandyari, E-mail: ali.esfandiari.bayat@gmail.com; Junin, Radzuan [Universiti Teknologi Malaysia, Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering (Malaysia); Mohsin, Rahmat [Universiti Teknologi Malaysia, UTM-MPRC Institute for Oil and Gas, N29A, Lengkuk Suria (Malaysia); Hokmabadi, Mehrdad [Universiti Teknologi Malaysia, Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering (Malaysia); Shamshirband, Shahaboddin [University of Malaya, Department of Computer System and Information Technology, Faculty of Computer System and Information Technology (Malaysia)

2015-05-15

Utilization of nanoparticles (NPs) for a broad range of applications has caused considerable quantities of these materials to be released into the environment. Issues of how and where the NPs are distributed into the subsurface aquatic environments are questions for those in environmental engineering. This study investigated the influence of three abundant clay minerals namely kaolinite, montmorillonite, and illite in the subsurface natural aquatic systems on the transport and retention of aluminum oxide (Al{sub 2}O{sub 3}, 40 nm) and titanium dioxide (TiO{sub 2}, 10–30 nm) NPs through saturated limestone porous media. The clay concentrations in porous media were set at 2 and 4 vol% of the holder capacity. Breakthrough curves in the columns outlets were measured using a UV–Vis spectrophotometer. It was found that the maximum NPs recoveries were obtained when there was no clay particle in the porous medium. On the other hand, increase in concentration of clay particles has resulted in the NPs recoveries being significantly declined. Due to fibrous structure of illite, it was found to be more effective for NPs retention in comparison to montmorillonite and kaolinite. Overall, the position of clay particles in the porous media pores and their morphologies were found to be two main reasons for increase of NPs retention in porous media.

Decoupling and tuning competing effects of different types of defects on flux creep in irradiated YBa<sub>2sub>Cu>3sub>O>7-δsub> coated conductors

Energy Technology Data Exchange (ETDEWEB)

Eley, S.; Leroux, M.; Rupich, M. W.; Miller, D. J.; Sheng, H.; Niraula, P. M.; Kayani, A.; Welp, U.; Kwok, W. -K.; Civale, L.

2016-11-15

YBa<sub>2sub>Cu>3sub>O>7-δsub> coated conductors (CCs) have achieved high critical current densities (J <sub>c>) that can be further increased through the introduction of additional defects using particle irradiation. However, these gains are accompanied by increases in the flux creep rate, a manifestation of competition between the different types of defects. Here, we study this competition to better understand how to design pinning landscapes that simultaneously increase J c and reduce creep. CCs grown by metal organic deposition show non-monotonic changes in the temperature-dependent creep rate, S(T). Notably, in low fields, there is a conspicuous dip to low S as the temperature (T) increases from ~20 to ~65 K. Oxygen-, proton-, and Au-irradiation substantially increase S in this temperature range. Focusing on an oxygen-irradiated CC, we investigate the contribution of different types of irradiation-induced defects to the flux creep rate. Specifically, we study S(T) as we tune the relative density of point defects to larger defects by annealing both an as-grown and an irradiated CC in O<sub>2sub> at temperatures T <sub>A> = 250 °C–600 °C. We observe a steady decrease in S(T > 20 K) with increasing T <sub>A>, unveiling the role of pre-existing nanoparticle precipitates in creating the dip in S(T) and point defects and clusters in increasing S at intermediate temperatures.

Synthesis of sub-10 nm VO{sub 2} nanoparticles films with plasma-treated glass slides by aqueous sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Lan, Shi-Di [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan (China); Huang, Chi-Hsien [Department of Materials Engineering, Ming Chi University of Technology, 84 Gungjuan Road, Taishan Dist., New Taipei City 24301, Taiwan (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China)

2015-12-01

Highlights: • Sub-10 nm VO{sub 2} nanoparticles (VNPs) are synthesized on a plasma-treated glass. • Glass slides generate negative charges sites after plasma treatment to attract VO{sub 2}{sup +}. • Doping tungsten with 1 wt% in VNPs did not change particle size significantly. • The particle size of VNP can be tuned by the density of negative charge sites. • Sub-10 nm structured VO{sub 2} particle films exhibited high visible transmittance. - Abstract: This paper describes an aqueous sol–gel synthesis of thermochromic thin films consisted of vanadium dioxide nanoparticles (VNPs) on glass slides. The glass slides were treated by argon/oxygen plasma to generate dispersedly negative charge sites on the surface to attract VO{sub 2}{sup +} from a sol–gel solution. After heat treatment in a low-pressure carbon monoxide/carbon dioxide (CO/CO{sub 2}) atmosphere, the VNPs could be generated in sub-10 nm of particle size on the surface. Various levels of doping were achieved by adding small quantities of a water-soluble tungsten compound to the sol; however, the particle size increased slightly with the tungsten doping levels. The change in electrical conductivity with temperature for VNP films were measured and compared to VO{sub 2} crystalline films. VNP films exhibited the lower transition temperature of the semiconductor to metal phase change; at a doping level of 4 wt% the transition temperature was measured at 32.2 ± 1.2 and 24.1 ± 1.2 °C for the VO{sub 2} and VNP films, respectively. The VNP films showed excellent visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal–insulator phase transition (MIT). The current method is a landmark in the development of nanostructured material toward applications in energy-saving smart windows.

Size-dependent photodegradation of CdS particles deposited onto TiO{sub 2} mesoporous films by SILAR method

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Rasin; Will, Geoffrey; Bell, John; Wang Hongxia, E-mail: hx.wang@qut.edu.au [Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering (Australia)

2012-09-15

The particle size, size distribution and photostability of CdS nanoparticles incorporated onto mesoporous TiO{sub 2} films by a successive ionic layer adsorption and reaction (SILAR) method were investigated by Raman spectroscopy, UV-Visible spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). High-resolution TEM indicated that the synthesized CdS particles were hexagonal phase and the particle sizes were less than 5 nm for up to nine SILAR deposition cycles. Quantum size effect was found with the CdS-sensitized TiO{sub 2} films prepared with up to nine SILAR cycles. The band gap of CdS nanoparticles decreased from 2.65 to 2.37 eV with the increase of the SILAR cycles from 1 to 11. The investigation of the stability of the CdS/TiO{sub 2} films in air under illumination (440.6 {mu}W/cm{sup 2}) showed that the photodegradation rate was up to 85 % per day for the sample prepared with three SILAR cycles. XPS analysis indicated that the photodegradation was due to the oxidation of CdS, leading to the transformation from sulphide to sulphate (CdSO{sub 4}). Furthermore, the degradation rate was strongly dependent upon the particle size of CdS. Smaller particles showed faster degradation rate. The size-dependent photo-induced oxidization was rationalized with the variation of size-dependent distribution of surface atoms of CdS particles. Molecular dynamics-based theoretical calculation has indicated that the surface sulphide anion of a large CdS particle such as CdS made with 11 cycles (CdS Multiplication-Sign 11, average particle size = 5.6 nm) accounts for 9.6 % of the material whereas this value is increased to 19.2 % for (CdS Multiplication-Sign 3)-based smaller particles (average particle size = 2.7 nm). The photostability of CdS nanoparticles was significantly enhanced when coated with ZnS particles deposited with four SILAR cycles. The growth mechanism of ZnS upon CdS nanoparticles was discussed.

Hepatitis B in sub-Saharan Africa: strategies to achieve the 2030 elimination targets.

Science.gov (United States)

Spearman, C Wendy; Afihene, Mary; Ally, Reidwaan; Apica, Betty; Awuku, Yaw; Cunha, Lina; Dusheiko, Geoffrey; Gogela, Neliswa; Kassianides, Chris; Kew, Michael; Lam, Philip; Lesi, Olufunmilayo; Lohouès-Kouacou, Marie-Jeanne; Mbaye, Papa Saliou; Musabeyezu, Emmanuel; Musau, Betty; Ojo, Olusegun; Rwegasha, John; Scholz, Barbara; Shewaye, Abate B; Tzeuton, Christian; Sonderup, Mark W

2017-12-01

The WHO global health sector strategy on viral hepatitis, created in May, 2016, aims to achieve a 90% reduction in new cases of chronic hepatitis B and C and a 65% reduction in mortality due to hepatitis B and C by 2030. Hepatitis B virus (HBV) is endemic in sub-Saharan Africa, and despite the introduction of universal hepatitis B vaccination and effective antiviral therapy, the estimated overall seroprevalence of hepatitis B surface antigen remains high at 6·1% (95% uncertainty interval 4·6-8·5). In this Series paper, we have reviewed the literature to examine the epidemiology, burden of liver disease, and elimination strategies of hepatitis B in sub-Saharan Africa. This paper reflects a supranational perspective of sub-Saharan Africa, and recommends several priority elimination strategies that address the need both to prevent new infections and to diagnose and treat chronic infections. The key to achieving these elimination goals in sub-Saharan Africa is the effective prevention of new infections via universal implementation of the HBV birth-dose vaccine, full vaccine coverage, access to affordable diagnostics to identify HBV-infected individuals, and to enable linkage to care and antiviral therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of MnCuFe{sub 2}O{sub 4} content on magnetic and dielectric properties of poly (O-Phenylenediamine)/MnCuFe{sub 2}O{sub 4} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Kannapiran, Nagarajan [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Chitra, Palanisamy [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

2016-03-01

Poly o-phenylenediamine (PoPD)/MnCuFe{sub 2}O{sub 4} nanocomposites with three different ratios of MnCuFe{sub 2}O{sub 4} (10%, 20%, 30% w/w) were synthesized by in-situ oxidative chemical polymerization method ammonium persulphate used as oxidant, while MnCuFe{sub 2}O{sub 4} nanoparticles was prepared by auto-combustion method. The structure, morphology and magnetic properties of synthesized PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites were characterized by FT-IR, UV–visible absorption spectra, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Vibrating sample magnetometer (VSM). FTIR spectra and XRD were confirmed the formation of the PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites. The morphology of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites is visualized through SEM and TEM. The spherical morphology of the PoPD was confirmed using SEM analysis. Dielectric properties of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites at different temperatures have been performed in the frequency range of 50 Hz–5 MHz. The optical absorption experiments of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites reveal that the direct transition with an energy band gap is around 2 eV. - Highlights: • Green synthesis of PoPD (the polymerization carried out only in aqueous medium) by in-situ chemical polymerization method. • For the first time, PoPD incorporated with MnCuFe{sub 2}O{sub 4} with lesser particle size. • The auto combustion reaction, support to achieve less particle size. • Ferrite content affects the magnetic properties of the nanocomposites.

Synthesis of MSnO{sub 3} (M = Ba, Sr) nanoparticles by reverse micelle method and particle size distribution analysis by whole powder pattern modeling

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Jahangeer; Blakely, Colin K.; Bruno, Shaun R. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Poltavets, Viktor V., E-mail: poltavets@chemistry.msu.edu [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States)

2012-09-15

Highlights: ► BaSnO{sub 3} and SrSnO{sub 3} nanoparticles synthesized using the reverse micelle method. ► Particle size and size distribution studied by whole powder pattern modeling. ► Nanoparticles are of optimal size for investigation in dye-sensitized solar cells. -- Abstract: Light-to-electricity conversion efficiency in dye-sensitized solar cells critically depends not only on the dye molecule, semiconducting material and redox shuttle selection but also on the particle size and particle size distribution of the semiconducting photoanode. In this study, nanocrystalline BaSnO{sub 3} and SrSnO{sub 3} particles have been synthesized using the microemulsion method. Particle size distribution was studied by whole powder pattern modeling which confirmed narrow particle size distribution with an average size of 18.4 ± 8.3 nm for SrSnO{sub 3} and 15.8 ± 4.2 nm for BaSnO{sub 3}. These values are in close agreement with results of transmission electron microscopy. The prepared materials have optimal microstructure for successive investigation in dye-sensitized solar cells.

Multiwall carbon nanotubes decorated with FeCr{sub 2}O{sub 4}, a new selective electrochemical sensor for amoxicillin determination

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali Asghar, E-mail: Ensafi@cc.iut.ac.ir; Allafchian, Ali Reza; Rezaei, Behzad [Isfahan University of Technology, Department of Chemistry (Iran, Islamic Republic of)

2012-11-15

FeCr{sub 2}O{sub 4} nanoparticles were synthesized and then multiwall carbon nanotubes (MWCNTs) were decorated with FeCr{sub 2}O{sub 4} nanoparticles. The new nanoparticles were characterized with different techniques such as vibrating sample magnetometer, Fourier transform infrared spectroscopy, scanning surface microscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. The results of the study confirm that the particles are pure FeCr{sub 2}O{sub 4}-MWCNTs with a cubic structure. No diffraction peaks of other impurities such as FeO or Cr{sub 2}O{sub 3} were observed. The diffractive peaks of FeCr{sub 2}O{sub 4}-MWCNTs are broadened, implying that the crystalline size of FeCr{sub 2}O{sub 4}-MWCNTs particles is quite small. The mean particle size of FeCr{sub 2}O{sub 4}-MWCNTs calculated by Scherrer equation is about 25 nm, whereas the existence of particles with less than 30 nm size at FeCr{sub 2}O{sub 4}-MWCNTs is clearly reflected in 2D and 3D AFM images. The TEM image confirms that the spaghetti-like FeCr{sub 2}O{sub 4}-MWCNTs formed a porous structure. The synthesized FeCr{sub 2}O{sub 4}-MWCNTs nanoparticles could be used as a new electrocatalysis for voltammetric determination of amoxicillin (AMC). Under the optimized conditions at pH 7.5 and in differential pulse voltammetry, the oxidation peak current of AMC at the surface of the mediator has two linear dynamic ranges including 0.1-10.0 and 10.0-70.0 {mu}mol L{sup -1}. The detection limit of 0.05 {mu}mol L{sup -1} was achieved. The influence of potential interfering compounds on the selectivity was studied. Finally, the modified electrode showed good sensitivity, selectivity, and stability for the determination of AMC in real samples.

X-ray tomography studies on porosity and particle size distribution in cast in-situ Al-Cu-TiB{sub 2} semi-solid forged composites

Energy Technology Data Exchange (ETDEWEB)

Mathew, James; Mandal, Animesh [School of Minerals, Metallurgical and Materials Engineering, Indian Institute of Technology, Bhubaneswar (India); Warnett, Jason; Williams, Mark A. [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Chakraborty, Madhusudan [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Srirangam, Prakash, E-mail: p.srirangam@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom)

2016-08-15

X-ray computed tomography (XCT) was used to characterise the internal microstructure and clustering behaviour of TiB{sub 2} particles in in-situ processed Al-Cu metal matrix composites prepared by casting method. Forging was used in semi-solid state to reduce the porosity and to uniformly disperse TiB{sub 2} particles in the composite. Quantification of porosity and clustering of TiB{sub 2} particles was evaluated for different forging reductions (30% and 50% reductions) and compared with an as-cast sample using XCT. Results show that the porosity content was decreased by about 40% due to semi-solid forging as compared to the as-cast condition. Further, XCT results show that the 30% forging reduction resulted in greater uniformity in distribution of TiB{sub 2} particles within the composite compared to as-cast and the 50% forge reduction in semi-solid state. These results show that the application of forging in semi-solid state enhances particle distribution and reduces porosity formation in cast in-situ Al-Cu-TiB{sub 2} metal matrix composites. - Highlights: •XCT was used to visualise 3D internal structure of Al-Cu-TiB{sub 2} MMCs. •Al-Cu-TiB{sub 2} MMC was prepared by casting using flux assisted synthesis method. •TiB{sub 2} particles and porosity size distribution were evaluated. •Results show that forging in semi-solid condition decreases the porosity content and improve the particle dispersion in MMCs.

Preparation of transparent fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coating with improved self-cleaning performance and anti-aging property

Energy Technology Data Exchange (ETDEWEB)

Zhou, Jianping, E-mail: zf161162@163.com; Tan, Zhongyuan; Liu, Zhilei; Jing, Mengmeng; Liu, Wenjie; Fu, Wanli

2017-02-28

achieved for the composite coatings containing 1.5 wt% of TiO{sub 2}-SiO{sub 2} colloidal particles. The results of the anti-soiling experiments indicated that the fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings exhibited a prominent self-cleaning performance, while the accelerated aging experiments revealed that the fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings were highly stable toward UV irradiation when compared to the TiO{sub 2}-filled fluorocarbon coatings. These findings indicated that the fluorocarbon/TiO{sub 2}-SiO{sub 2} composite coatings could be a very attractive solution for many practical areas, especially for outdoor applications.

Ion beam characterisation of nanometre structures

International Nuclear Information System (INIS)

Persson, Leif.

1995-08-01

Ion beam analysis methods have been applied to the study of technologically important issues in III-V nanometre structure science. In the first application, the incorporation of hydrogen in GaAs during electron cyclotron resonance etching was studied using the 1 H( 15 N,αγ) 12 C reaction analysis method. The major part of the work was carried out using mass and energy dispersive Recoil Spectrometry (RS). RS was used to study reactions of thin metal films InP reactions. The metals investigated include Cr, Ti, Ni, Pd and Pt and the reactions as a function of temperature were studied to elucidate suitable compounds for contacts and metallization. Using 127 I in the 0.5A to 0.7A MeV region as the projectile, the depth profiles for the different elements were obtained. Complementary measurements with X-ray diffraction to obtain chemical phase information as well as scanning electron microscopy to study the surface morphology were also carried out. 59 refs, 15 figs

Temperature dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1}

Energy Technology Data Exchange (ETDEWEB)

Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Hernando, A.; Aragon, A.; Marin, P. [Instituto de Magnetismo Aplicado, IMA, P.O. Box 155, 28230 Madrid (Spain)

2012-09-25

Highlights: Black-Right-Pointing-Pointer An anomalous thermal dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles under 25 {mu}m powder particle, increasing Hc as temperature increases. Black-Right-Pointing-Pointer It is proposed that Cu rich regions at inter-grain boundaries could act as exchange decoupling regions contributing to the thermal increase of coercivity. Black-Right-Pointing-Pointer This anomalous thermal dependence points out that tailoring microstructure and size, by controlling the cooling rate of more adequate multiphase systems, could be a promising procedure to develop soft or hard magnets, avoiding Rare Earths metals that is nowadays an important target for the engineering of magnetic materials. - Abstract: In this work, the dependence of the coercive field of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} gas atomized powder with the temperature for different particle sizes has been studied, observing an anomalous behavior in the under 25 powder particle size fraction. This unusual behavior is related with the microstructure of the powder, and is attributed to the presence of a multiphase magnetic system, with non-magnetic regions decoupling the ferromagnetic domains.

Room Temperature Radiolytic Synthesized Cu@CuAlO<sub>2sub>-Al>2sub>O>3sub> Nanoparticles

Directory of Open Access Journals (Sweden)

Nayereh Soltani

2012-09-01

Full Text Available Colloidal Cu@CuAlO<sub>2sub>-Al>2sub>O>3sub> bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a ⁶⁰Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO<sub>2sub>-Al>2sub>O>3sub> nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM, energy dispersive X-ray spectrometry (EDX, and X-ray diffraction (XRD showed that Cu@CuAlO<sub>2sub>-Al>2sub>O>3sub> nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

Synthesis and characterization of MoS{sub 2} cocatalysts for H{sub 2}-generation; Darstellung und Charakterisierung von MoS{sub 2} Cokatalysatoren fuer die H{sub 2}-Entwicklung

Energy Technology Data Exchange (ETDEWEB)

Djamil, John

2015-10-05

} nanoparticles as a function of milling time but with the same chemical composition. In doing so, the MoS{sub 2} stacking was reduced more rapidly than the slab length, yielding in increasing aspects ratios and thus affecting the particle shape. All nanosized cocatalysts exceeded bulk MoS{sub 2} in light driven hydrogen generation. The enhancement of H{sub 2} generation on MoS{sub 2} was achieved by addition of carbon, improving the electron conductivity and suppressing recombination processes. The positive influence of MoS{sub 2} edge sites on H{sub 2} generation was proofed by structural properties of the cocatalysts. Additionally, the importance of the particle shape on photocatalytic properties was demonstrated. Photocatalytic investigations on novel transition metal sulfides and -oxides for H{sub 2} evolution yielded in a rash of promising materials.

Communication of Information with Sub-particles (Sub-strings) from Fifth Dimension of the Universe (Information) as the ``Fundamental Symmetry'' in the Nature

Science.gov (United States)

Gholibeigian, Hassan; Gholibeigian, Ghasem; Amirshahkarami, Abdolazim; Gholibeigian, Kazem

2016-10-01

Fundamental particles (strings) getting processed information from their four animated sub-particles (sub-strings) for their motion [Gholibeigian, APS, 2015, abstract #L1.027]. It seems that the source of information which particles and dark mater/energy are floating in it and whispering to its communication for getting order may be ``fifth dimension'' of the nature in addition of space-time dimensions. In other words, space-time can be the universe's hardware and information's dimension can be dynamic software of the universe which has always become up to date. Communication of information which has a vital role in creation and evolution of the universe, may be as the ``fundamental symmetry'' in the nature, which sparked to B.B. (Convection Bang). Communication of information leads other symmetries and supersymmetry as well as other phenomena in Universe. Before Planck time, from 0 ->10-44 second, and its correspondence space needed communication of information for preparing the B.B. So, this fifth dimension has appeared for leading the processes before and after Planck time. AmirKabir University of Technology, Tehran, Iran.

Exchange coupling behavior in bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Leite, G.C.P. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Chagas, E.F., E-mail: efchagas@fisica.ufmt.br [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Pereira, R.; Prado, R.J. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Terezo, A.J. [Departamento de Quimica, Universidade Federal do Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Alzamora, M.; Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150 Urca, Rio de Janeiro (Brazil)

2012-09-15

In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe{sub 2}O{sub 4} and ferrimagnetic oxide/ferromagnetic metal CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite. The latter compound is a good system to study hard ferrimagnet/soft ferromagnet exchange coupled. Two steps were followed to synthesize the bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite: (i) first, preparation of CoFe{sub 2}O{sub 4} nanoparticles using a simple hydrothermal method, and (ii) second, reduction reaction of cobalt ferrite nanoparticles using activated charcoal in inert atmosphere and high temperature. The phase structures, particle sizes, morphology, and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles were investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) with applied field up to 3.0 kOe at room temperature and 50 K. The mean diameter of CoFe{sub 2}O{sub 4} particles is about 16 nm. Mossbauer spectra revealed two sites for Fe{sup 3+}. One site is related to Fe in an octahedral coordination and the other one to the Fe{sup 3+} in a tetrahedral coordination, as expected for a spinel crystal structure of CoFe{sub 2}O{sub 4}. TEM measurements of nanocomposite showed the formation of a thin shell of CoFe{sub 2} on the cobalt ferrite and indicate that the nanoparticles increase to about 100 nm. The magnetization of the nanocomposite showed a hysteresis loop that is characteristic of exchange coupled systems. A maximum energy product (BH){sub max} of 1.22 MGOe was achieved at room temperature for CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposites, which is about 115% higher than the value obtained for CoFe{sub 2}O{sub 4} precursor. The exchange coupling interaction and the enhancement of product (BH){sub max} in nanocomposite CoFe{sub 2}O{sub 4}/CoFe{sub 2} are discussed. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

Superparamagnetic behavior of nanosized Co{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} synthesized by a flow rate controlled chemical coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Dey, S. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Dey, S.K. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Department of Physics, NITMAS, 24 Pargana(s) 743368 (India); Majumder, S. [Department of Physics, Jadavpur University, Kolkata 700032 (India); Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Poddar, A.; Dasgupta, P.; Banerjee, S. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Kumar, S., E-mail: kumars@phys.jdvu.ac.in [Department of Physics, Jadavpur University, Kolkata 700032 (India)

2014-09-01

We have studied the structural, microstructural and magnetic properties of nanosized (∼20 nm) Co{sub 0.2}Zn{sub 0.8}Fe{sub 2}O{sub 4} synthesized by a flow rate controlled coprecipitation method. The phase purity and crystallinity of the sample have been confirmed by powder X-ray diffraction and high resolution transmission electron microscopic studies. According to the results of dc magnetic measurements the sample exhibits superparamagnetic behavior above 70 K due to its nanometric size. This has been corroborated by Mössbauer spectroscopic study at 300 K. The infield Mössbauer spectroscopic study indicates that the sample behaves ferrimagnetically at 10 K and it possesses equilibrium cation distribution. The saturation magnetization of the sample (M{sub SAT}∼32 emu g{sup −1} at 300 K) is substantially lower than its bulk counterpart (M{sub SAT}=80 emu g{sup −1}) but higher than those having same composition synthesized by the conventional coprecipitation method. This has been attributed to finite size and spin canting effects as well as good crystalline character and bulk like equilibrium cation distribution of the sample. We have shown that the flow rate controlled coprecipitation method can produce nanosized ferrites with very good crystalline order and equilibrium cation distribution but they exhibit reduction of magnetization, magnetic order and ordering temperature compared to their bulk counterparts due to spin canting effect and finite size effect.

Thermoelectric properties of In{sub 0.2}Co{sub 4}Sb{sub 12} skutterudites with embedded PbTe or ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chubilleau, C.; Lenoir, B.; Candolfi, C.; Masschelein, P. [Université de Lorraine, CNRS, UMR 7198, Institut Jean Lamour, Parc de Saurupt, 54011 Nancy (France); Dauscher, A., E-mail: anne.dauscher@univ-lorraine.fr [Université de Lorraine, CNRS, UMR 7198, Institut Jean Lamour, Parc de Saurupt, 54011 Nancy (France); Guilmeau, E. [Laboratoire CRISMAT, UMR 6508, 6 boulevard Maréchal Juin, 14050 Caen Cedex (France); Godart, C. [ICMPE-CMTR, CNRS-UMR 7182, 2-8 rue H. Dunant, 94320 Thiais (France)

2014-03-15

Highlights: • Fabrication of nanostructured skutterudites ZnO or PbTe/In{sub 0.2}Co{sub 4}Sb{sub 12.} • Thermal conductivity modeling accounts for experimental results. • Greater lattice thermal conductivity decrease in In{sub 0.2}Co{sub 4}Sb{sub 12} than in CoSb{sub 3}. • A max ZT of 1.05 is obtained at 700 K in a 2 wt% ZnO-containing sample. -- Abstract: Transport properties of the skutterudite compound In{sub 0.2}Co{sub 4}Sb{sub 12} containing ZnO or PbTe nano-sized particles (2–12 wt%) were investigated by means of electrical resistivity, thermopower and thermal conductivity between 5 and 800 K. The composite powders were prepared by freeze-drying the nanoparticles with micron-sized In{sub 0.2}Co{sub 4}Sb{sub 12} powders. Densification was achieved by spark plasma sintering. All composites were characterized by X-ray powder diffraction and scanning electron microscopy. All the transport coefficients show similar temperature dependences suggesting little influence of the nature, semiconducting or insulating, of the nanoparticles. Both the electrical and the thermal conductivities decrease with increasing the PbTe or ZnO content. The impact of ZnO and PbTe on the thermal conductivity was modelled based on the Debye model taking into account a relaxation time constant reflecting phonon scattering by spherical nanoparticles. A maximum dimensionless figure of merit ZT of 1.05 at 700 K was achieved in a sample containing 2 wt% ZnO, a value quite similar to that of the reference In{sub 0.2}Co{sub 4}Sb{sub 12} compound.

The importance of SO{sub 2} and SO{sub 3} for sulphation of gaseous KCl - An experimental investigation in a biomass fired CFB boiler

Energy Technology Data Exchange (ETDEWEB)

Kassman, Haakan [Vattenfall Power Consultant AB, Nykoeping (Sweden); Chalmers University of Technology, Department of Energy and Environment, Division of Energy Technology, Gothenburg (Sweden); Baefver, Linda [Technical Research Institute of Sweden, Energy Technology, Boraas (Sweden); Aamand, Lars-Erik [Chalmers University of Technology, Department of Energy and Environment, Division of Energy Technology, Gothenburg (Sweden)

2010-09-15

This paper is based on results obtained during co-combustion of wood pellets and straw in a 12 MW circulating fluidised bed (CFB) boiler. Elemental sulphur (S) and ammonium sulphate ((NH{sub 4}){sub 2}SO{sub 4}) were used as additives to convert the alkali chlorides (mainly KCl) to less corrosive alkali sulphates. Their performance was then evaluated using several measurement tools including, IACM (on-line measurements of gaseous alkali chlorides), a low-pressure impactor (particle size distribution and chemical composition of extracted fly ash particles), and deposit probes (chemical composition in deposits collected). The importance of the presence of either SO{sub 2} or SO{sub 3} for gas phase sulphation of KCl is also discussed. Ammonium sulphate performed significantly better than elemental sulphur. A more efficient sulphation of gaseous KCl was achieved with (NH{sub 4}){sub 2}SO{sub 4} even when the S/Cl molar ratio was less than half compared to sulphur. Thus the presence of gaseous SO{sub 3} is of greater importance than that of SO{sub 2} for the sulphation of gaseous KCl. (author)

Synthesis and characterization of nanometric zinc oxide for a stationary phase in liquid chromatography

International Nuclear Information System (INIS)

Gordillo-Delgado, F; Soto-Barrera, C C; Plazas-Saldaña, J

2017-01-01

The increasing demand for equipment to remove organic compounds in industry and research activity has led to evaluate nanometric zinc oxide (ZnO). In this work, we present the ZnO nanoparticles synthesis for reusing of discarded columns, as a low-cost alternative. The compound was obtained by sol-gel technique using zinc chloride and sodium hydroxide as precursors and a drying temperature of 169°C. An X-ray diffractometer was used to estimate the average particle size at 20.3±0.2nm; the adsorption capacity was 0.0144L/g and the chemical resistance was tested with HCl and NaOH. The ZnO nanopowder was packed with 100psi pressure in an empty C-18 column cavity. The column packing resolution was evaluated using a high performance liquid chromatographer (HPLC-Thermo Scientific Dionex UltiMate 3000); using a caffeine standard, the following parameters were established: solvent flow: 1.2mL/min, average column temperature: 40°C, running time: 10 minutes, mobile phase acetonitrile-water composition (9:1). These results validate the potential of ZnO nanopowder as a column packing material in HPLC technique. (paper)

Synthesis and characterization of nanometric zinc oxide for a stationary phase in liquid chromatography

Science.gov (United States)

Gordillo-Delgado, F.; Soto-Barrera, C. C.; Plazas-Saldaña, J.

2017-01-01

The increasing demand for equipment to remove organic compounds in industry and research activity has led to evaluate nanometric zinc oxide (ZnO). In this work, we present the ZnO nanoparticles synthesis for reusing of discarded columns, as a low-cost alternative. The compound was obtained by sol-gel technique using zinc chloride and sodium hydroxide as precursors and a drying temperature of 169°C. An X-ray diffractometer was used to estimate the average particle size at 20.3±0.2nm the adsorption capacity was 0.0144L/g and the chemical resistance was tested with HCl and NaOH. The ZnO nanopowder was packed with 100psi pressure in an empty C-18 column cavity. The column packing resolution was evaluated using a high performance liquid chromatographer (HPLC-Thermo Scientific Dionex UltiMate 3000); using a caffeine standard, the following parameters were established: solvent flow: 1.2mL/min, average column temperature: 40°C, running time: 10 minutes, mobile phase acetonitrile-water composition (9:1). These results validate the potential of ZnO nanopowder as a column packing material in HPLC technique.

Harmonic decomposition of two particle angular correlations in Pb-Pb collisions at {radical}(s{sub NN})=2.76 TeV

Energy Technology Data Exchange (ETDEWEB)

Aamodt, K. [Department of Physics and Technology, University of Bergen, Bergen (Norway); Abelev, B. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Abrahantes Quintana, A. [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Havana (Cuba); Adamova, D. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez u Prahy (Czech Republic); Adare, A.M., E-mail: andrew.adare@yale.edu [Yale University, New Haven, CT (United States); Aggarwal, M.M. [Physics Department, Panjab University, Chandigarh (India); Aglieri Rinella, G. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Agocs, A.G. [KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest (Hungary); Agostinelli, A. [Dipartimento di Fisica dell' Universita and Sezione INFN, Bologna (Italy); Aguilar Salazar, S. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); Ahammed, Z. [Variable Energy Cyclotron Centre, Kolkata (India); Ahmad, N.; Ahmad Masoodi, A. [Department of Physics Aligarh Muslim University, Aligarh (India); Ahn, S.U. [Gangneung-Wonju National University, Gangneung (Korea, Republic of); Akindinov, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Aleksandrov, D. [Russian Research Centre Kurchatov Institute, Moscow (Russian Federation); Alessandro, B. [Sezione INFN, Turin (Italy); Alfaro Molina, R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Mexico City (Mexico); and others

2012-02-28

Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb-Pb collisions at {radical}(s{sub NN})=2.76 TeV for transverse momenta 0.25sub T}{sup t,a}<15 GeV/c, where p{sub T}{sup t}>p{sub T}{sup a}. The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |{eta}|<1.0. Distributions in relative azimuth {Delta}{phi}{identical_to}{phi}{sup t}-{phi}{sup a} are analyzed for |{Delta}{eta}|{identical_to}|{eta}{sup t}-{eta}{sup a}|>0.8, and are referred to as 'long-range correlations'. Fourier components V{sub n{Delta}}{identical_to} Left-Pointing-Angle-Bracket cos(n{Delta}{phi}) Right-Pointing-Angle-Bracket are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a}) is fully described in terms of single-particle anisotropies v{sub n}(p{sub T}) as V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a})=v{sub n}(p{sub T}{sup t})v{sub n}(p{sub T}{sup a}). This expectation is tested for 1 Less-Than-Or-Slanted-Equal-To n Less-Than-Or-Slanted-Equal-To 5 by applying a global fit of all V{sub n{Delta}}(p{sub T}{sup t},p{sub T}{sup a}) to obtain the best values v{sub n}{l_brace}GF{r_brace}(p{sub T}). It is found that for 2 Less-Than-Or-Slanted-Equal-To n Less-Than-Or-Slanted-Equal-To 5, the fit agrees well with data up to p{sub T}{sup a}{approx}3-4 GeV/c, with a trend of increasing deviation as p{sub T}{sup t} and p{sub T}{sup a} are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25sub T}<15 GeV/c range using a single v{sub n}(p{sub T}) curve; such a description is however

Microplastic deformation of TiB/sub 2/ particles during vibrocrushing and pressing in high pressure chambers

Energy Technology Data Exchange (ETDEWEB)

Ordan' yan, S.S.; Kravchik, A.E.; Ponomarenko, V.A.; Chunov, V.D. (Leningradskij Tekhnologicheskij Inst. (USSR))

1984-04-01

The character of plastic strain in titanium diboride particles is described. It is shown that during titanium diboride vibrocrushing unlike that of carbide there is practically no microplastic deformation that is observed only when TiB/sub 2/ particles are squeezed in high-pressure chambers at pressures not less than 3GPa.

The CERN Resonant Weakly Interacting Sub-eV Particle Search (CROWS)

CERN Document Server

Betz, Michael; Gasior, Marek; Thumm, Manfred

The subject of this thesis is the design, implementation and first results of the ``CERN Resonant WISP Search'' (CROWS) experiment, which probes the existence of Weakly Interacting Sub-eV Particles (WISPs) using microwave techniques. Axion Like Particles and Hidden Sector Photons are two well motivated members of the WISP family. Their existence could reveal the composition of cold dark matter in the universe and explain a large number of astrophysical phenomena. Particularly, the discovery of an axion would solve a long standing issue in the standard model, known as the ``strong CP problem''. Despite their strong theoretical motivation, the hypothetical particles have not been observed in any experiment so far. One way to probe the existence of WISPs is to exploit their interaction with photons in a ``light shining through the wall'' experiment. A laser beam is guided through a strong magnetic field in the ``emitting region'' of the experiment. This provides photons, which can convert into hypothetical Axi...

Removal of fine particles in wet flue gas desulfurization system by heterogeneous condensation

Energy Technology Data Exchange (ETDEWEB)

Yang, L.J.; Bao, J.J.; Yan, J.P.; Liu, J.H.; Song, S.J.; Fan, F.X. [Southeast University, Nanjing (China). School of Energy & Environment

2010-01-01

A novel process to remove fine particles with high efficiency by heterogeneous condensation in a wet flue gas desulfurization (WFGD) system is presented. A supersaturated vapor phase, necessary for condensational growth of fine particles, was achieved in the SO{sub 2} absorption zone and at the top of the wet FGD scrubber by adding steam in the gas inlet and above the scrubbing liquid inlet of the scrubber, respectively. The condensational grown droplets were then removed by the scrubbing liquid and a high-efficiency demister. The results show that the effectiveness of the WFGD system for removal of fine particles is related to the SO{sub 2} absorbent employed. When using CaCO{sub 3} and NH{sub 3} {center_dot} H{sub 2}O to remove SO{sub 2} from flue gas, the fine particle removal efficiencies are lower than those for Na2CO{sub 3} and water, and the morphology and elemental composition of fine particles are changed. This effect can be attributed to the formation of aerosol particles in the limestone and ammonia-based FGD processes. The performance of the WFGD system for removal of fine particles can be significantly improved for both steam addition cases, for which the removal efficiency increases with increasing amount of added steam. A high liquid to gas ratio is beneficial for efficient removal of fine particles by heterogeneous condensation of water vapor.

Investigation of phases developed in Bi/sub 4/Ti/sub 3/O/sub 12/ system by thermal and analytical techniques

International Nuclear Information System (INIS)

Naz, S.; Shazad, S.; Qureshi, A.H.; Waqas, H.; Hussain, N.; Ahmed, N.; Saeed, K.; Ali, L.

2012-01-01

Bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/) powders were prepared by conventional mixed oxide method using oxide mixture i.e. bismuth oxide (Bi/sub 2/O/sub 3/) and titanium oxide (TiO/sub 3). The mixed powders were ball milled for different times (8, 16, and 24 hours). The phase formation was investigated by X-ray diffraction (XRD) and the results revealed that milled powder mainly consisted of Bi/sub 2/O/sub 3/ and TiO/sub 2 /phases and a small amount corresponded to Bi/sub 4/Ti/sub 3/O/sub 12/. However, after calcination at 700 deg. C, Bi/sub 4/Ti/sub 3/O/sub 12/ phase was mainly observed. Thermal decomposition (Differential Scanning Calorimetry (DSC)-Thermal Gravimetric Analysis (TGA)-Differential Thermometric Analysis (DTA)) and XRD results showed that the formation of desired phase Bi/sub 4/Ti/sub 3/O/sub 12/ was only possible above 600 deg. C. Single phase Bi/sub 4/Ti/sub 3/O/sub 12/ ceramic was obtained with the orthorhombic structure in three pellets by sintering at 800 deg. C. XRD patterns of sintered pellets are shown. Maximum density (8.61 g/cm/sup 3/) was achieved in the sample milled for 24 hours due to reduction in particle size which ultimately enhanced the diffusion process during sintering. (Orig./A.B.)

Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

International Nuclear Information System (INIS)

Uzu, G.; Sobanska, S.; Aliouane, Y.; Pradere, P.; Dumat, C.

2009-01-01

Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 ± 20 mg Pb kg -1 ) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO 4 , PbSO 4 .PbO, α-PbO and Pb 0 . Morphology investigations revealed that PM 2.5 (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 μm or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl 2 extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size

Comparative study of nano-sized particles CoFe{sub 2}O{sub 4} effects on superconducting properties of Y-123 and Y-358

Energy Technology Data Exchange (ETDEWEB)

Slimani, Y.; Hannachi, E.; Ben Salem, M.K.; Hamrita, A. [Laboratory of Physics of Materials-Structures and Properties, Department of Physics, Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna (Tunisia); Varilci, A. [Faculty of Arts and Sciences, Department of Physics, Abant Izzet Baysal University, 14280 Bolu (Turkey); Dachraoui, W. [CINaM-CNRS, Luminy Campus, 13288 Marseille (France); Ben Salem, M., E-mail: salemwiem2005@yahoo.fr [Laboratory of Physics of Materials-Structures and Properties, Department of Physics, Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna (Tunisia); Ben Azzouz, F. [Laboratory of Physics of Materials-Structures and Properties, Department of Physics, Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna (Tunisia); College of Sciences-Girls, Department of Physics, University of Dammam (Saudi Arabia)

2014-10-01

The effects of nano-sized CoFe{sub 2}O{sub 4} particles (10 nm) addition on the structural and the normal state resistivity of YBa{sub 2}Cu{sub 3}O{sub 7} (noted Y-123) and Y{sub 3}Ba{sub 5}Cu{sub 8}O{sub 18} (noted Y-358) polycrystalline were systematically studied. Samples were synthesized in oxygen atmosphere using a standard solid state reaction technique by adding CoFe{sub 2}O{sub 4} up to 2 wt%. Phases, microstructure and superconductivity have been systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical measurements ρ(T). XRD results reveal that the lattice parameters change for both Y-123 and Y-358 phases. SEM observations reveal that the grain size is reduced with increasing the content of CoFe{sub 2}O{sub 4}. The measurements for the resistivity dependence of temperature show that the depression in superconducting temperature is more pronounced for CoFe{sub 2}O{sub 4} addition in Y-358 compound than in Y-123 one. These results may be attributed to the existence of much more disorder due to a greater number of Cu sites to be substituted by Fe and Co in Y-358 compared to Y-123.

Metal-insulator-metal diodes with sub-nanometre surface roughness for energy-harvesting applications

KAUST Repository

Khan, A.A.; Jayaswal, Gaurav; Gahaffar, F.A.; Shamim, Atif

2017-01-01

For ambient radio-frequency (RF) energy harvesting, the available power levels are quite low, and it is highly desirable that the rectifying diodes do not consume any power at all. Contrary to semiconducting diodes, a tunnelling diode – also known as a metal-insulator-metal (MIM) diode – can provide zero-bias rectification, provided the two metals have different work functions. This could result in a complete passive rectenna system. Despite great potential, MIM diodes have not been investigated much in the GHz-frequency regime due to challenging nano-fabrication requirements. In this work, we investigate zero-bias MIM diodes for RF energy-harvesting applications. We studied the surface roughness issue for the bottom metal of the MIM diode for various deposition techniques such as sputtering, atomic layer deposition (ALD) and electron-beam (e-beam) evaporation for crystalline metals as well as for an amorphous alloy, namely ZrCuAlNi. A surface roughness of sub-1nm has been achieved for both the crystalline metals as well as the amorphous alloy, which is vital for the reliable operation of the MIM diode. An MIM diode comprising of a Ti-ZnO-Pt combination yields a zero-bias responsivity of 0.25V−1 and a dynamic resistance of 1200Ω. Complete RF characterisation has been performed by integrating the MIM diode with a coplanar waveguide transmission line. The input impedance varies from 100Ω to 50Ω in the frequency range of between 2GHz and 10GHz, which can be easily matched to typical antenna impedances in this frequency range. Finally, a rectified DC voltage of 4.7mV is obtained for an incoming RF power of 0.4W at zero bias. These preliminary results of zero-bias rectification indicate that complete, passive rectennas (a rectifier and antenna combination) are feasible with further optimisation of MIM devices.

Metal-insulator-metal diodes with sub-nanometre surface roughness for energy-harvesting applications

KAUST Repository

Khan, A.A.

2017-07-27

For ambient radio-frequency (RF) energy harvesting, the available power levels are quite low, and it is highly desirable that the rectifying diodes do not consume any power at all. Contrary to semiconducting diodes, a tunnelling diode – also known as a metal-insulator-metal (MIM) diode – can provide zero-bias rectification, provided the two metals have different work functions. This could result in a complete passive rectenna system. Despite great potential, MIM diodes have not been investigated much in the GHz-frequency regime due to challenging nano-fabrication requirements. In this work, we investigate zero-bias MIM diodes for RF energy-harvesting applications. We studied the surface roughness issue for the bottom metal of the MIM diode for various deposition techniques such as sputtering, atomic layer deposition (ALD) and electron-beam (e-beam) evaporation for crystalline metals as well as for an amorphous alloy, namely ZrCuAlNi. A surface roughness of sub-1nm has been achieved for both the crystalline metals as well as the amorphous alloy, which is vital for the reliable operation of the MIM diode. An MIM diode comprising of a Ti-ZnO-Pt combination yields a zero-bias responsivity of 0.25V−1 and a dynamic resistance of 1200Ω. Complete RF characterisation has been performed by integrating the MIM diode with a coplanar waveguide transmission line. The input impedance varies from 100Ω to 50Ω in the frequency range of between 2GHz and 10GHz, which can be easily matched to typical antenna impedances in this frequency range. Finally, a rectified DC voltage of 4.7mV is obtained for an incoming RF power of 0.4W at zero bias. These preliminary results of zero-bias rectification indicate that complete, passive rectennas (a rectifier and antenna combination) are feasible with further optimisation of MIM devices.

ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

Energy Technology Data Exchange (ETDEWEB)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China)

2016-09-15

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Effects of nanometric inclusions on the microstructural characteristics and strengthening of a friction-stir processed aluminum–magnesium alloy

Energy Technology Data Exchange (ETDEWEB)

Khodabakhshi, F., E-mail: farzadkhodabakhshi83@gmail.com [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Boulevard, Shiraz (Iran, Islamic Republic of); Simchi, A., E-mail: simchi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Kokabi, A.H. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Švec, P. [Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava (Slovakia); Simančík, F. [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, Bratislava (Slovakia); Gerlich, A.P. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON (Canada)

2015-08-26

An aluminum–magnesium alloy was friction-stir processed in the presence of TiO{sub 2} nanoparticles which were pre-placed in a groove on the surface to produce a composite. Field emission-scanning and transmission electron microscopy studies show that solid state chemical reactions occur between the Al–Mg matrix and the ceramic particles upon the severe plastic deformation process. The microstructure of the aluminum alloy consists of a coarse grain structure, large complex (Fe,Mn,Cr){sub 3}SiAl{sub 12} particles, and small Mg{sub 2}Si precipitates. After friction stir processing, a deformed grain structure containing rod-like Al–Fe–Mn–Si precipitates is attained, along with cuboidal (~100 nm) Cr{sub 2} precipitates and spherical (~100 and 5 nm) Mg{sub 2}Si particles. In the presence of TiO{sub 2} nanoparticles, magnesium oxide (MgO) and titanium aluminide (Al{sub 3}Ti) nanophases are formed. It is shown that these microstructural modifications lead to a significant enhancement in the hardness and tensile strength of the aluminum alloy. The relationship between the microstructural evolution and mechanical properties and the role of hard inclusions are presented and discussed. An analysis based on strengthening models indicates that the yield strength of the nanocomposite is mainly controlled by dislocations and grain boundaries rather than the nano-scale inclusions.

Liquid CO<sub>2sub>/Coal Slurry for Feeding Low Rank Coal to Gasifiers

Energy Technology Data Exchange (ETDEWEB)

Marasigan, Jose [Electric Power Research Institute, Inc., Palo Alto, CA (United States); Goldstein, Harvey [Electric Power Research Institute, Inc., Palo Alto, CA (United States); Dooher, John [Electric Power Research Institute, Inc., Palo Alto, CA (United States)

2013-09-30

This study investigates the practicality of using a liquid CO<sub>2sub>/coal slurry preparation and feed system for the E-Gas™ gasifier in an integrated gasification combined cycle (IGCC) electric power generation plant configuration. Liquid CO<sub>2sub> has several property differences from water that make it attractive for the coal slurries used in coal gasification-based power plants. First, the viscosity of liquid CO<sub>2sub> is much lower than water. This means it should take less energy to pump liquid CO<sub>2sub> through a pipe compared to water. This also means that a higher solids concentration can be fed to the gasifier, which should decrease the heat requirement needed to vaporize the slurry. Second, the heat of vaporization of liquid CO<sub>2sub> is about 80% lower than water. This means that less heat from the gasification reactions is needed to vaporize the slurry. This should result in less oxygen needed to achieve a given gasifier temperature. And third, the surface tension of liquid CO<sub>2sub> is about 2 orders of magnitude lower than water, which should result in finer atomization of the liquid CO<sub>2sub> slurry, faster reaction times between the oxygen and coal particles, and better carbon conversion at the same gasifier temperature. EPRI and others have recognized the potential that liquid CO<sub>2sub> has in improving the performance of an IGCC plant and have previously conducted systemslevel analyses to evaluate this concept. These past studies have shown that a significant increase in IGCC performance can be achieved with liquid CO<sub>2sub> over water with certain gasifiers. Although these previous analyses had produced some positive results, they were still based on various assumptions for liquid CO<sub>2sub>/coal slurry properties.

Perovskite-type La{sub 2}Ti{sub 2}O{sub 7} mesoporous photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Onozuka, K.; Kawakami, Y.; Imai, H.; Yokoi, T.; Tatsumi, T. [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Kondo, J.N., E-mail: jnomura@res.titech.ac.jp [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

2012-08-15

Crystalline particles of mesoporous La{sub 2}Ti{sub 2}O{sub 7}, a perovskite-type material, were prepared by hydrothermal synthesis at 210 Degree-Sign C in the presence of structure directing agent. Crystallization and simultaneous sintering occurred in the time course of the hydrothermal treatment, resulting in the improvement in crystallinity with a sacrifice of the decrease in surface area. The photocatalytic property was evaluated by hydrogen evolution from water with methanol sacrificial agent. The increase and the decrease of the material in crystallinity and surface area were responsible for the photocatalytic activity: the activity was improved by crystallization but the concurrent decrease in surface area (increase in size) of crystalline particles was disadvantageous. - Graphical abstract: A homogeneous mixture of La and Ti oxide with amorphous inorganic network was hydrothermally crystallized at low temperatures to a perovskite-type La{sub 2}Ti{sub 2}O{sub 7}. The small La{sub 2}Ti{sub 2}O{sub 7} particles with high crystallinity showed a potential as a photocatalyst for H{sub 2} evolution. Highlights: Black-Right-Pointing-Pointer Crystalline mesopourous La{sub 2}Ti{sub 2}O{sub 7} was prepared. Black-Right-Pointing-Pointer Hydrothermal treatment encouraged low temperature crystallization. Black-Right-Pointing-Pointer Small crystalline domain was advantageous to a photocatalytic reaction.

Nanoscale mechanochemical wear of phosphate laser glass against a CeO{sub 2} particle in humid air

Energy Technology Data Exchange (ETDEWEB)

Yu, Jiaxin, E-mail: yujiaxin@swust.edu.cn [Key Laboratory of Testing Technology for Manufacturing Process, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010 (China); He, Hongtu; Zhang, Yafeng [Key Laboratory of Testing Technology for Manufacturing Process, Ministry of Education, Southwest University of Science and Technology, Mianyang 621010 (China); Hu, Hailong [Analysis and Testing Center, Southwest University of Science and Technology, Mianyang 621010 (China)

2017-01-15

Highlights: • Friction components of phosphate glass/CeO{sub 2} pair in humid air were quantified to understand the friction mechanism. • Severe nanoscale wear was directly observed by AFM topography on both phosphate glass and CeO{sub 2} particle in humid air. • The wearless behaviors of phosphate glass in vacuum were confirmed by the AFM phase image. • Capillary water bridge induced corrosion plays an important role in the mechanochemical wear of phosphate glass in air. - Abstract: Using an atomic force microscope, the friction and wear of phosphate laser glass against a CeO{sub 2} particle were quantitatively studied both in humid air and in vacuum, to reveal the water molecules induced mechanochemical wear mechanism of phosphate laser glass. The friction coefficient of the glass/CeO{sub 2} pair in air was found to be 5–7 times higher than that in vacuum due to the formation of a capillary water bridge at the friction interface, with a contribution of the capillary-related friction to the total friction coefficient as high as 65–79%. The capillary water bridge further induced a serious material removal of glass and CeO{sub 2} particle surfaces, while supplying both a local liquid water environment to corrode the glass surface and a high shearing force to assist the stretching of the Ce−O−P bond, accelerating the reaction between water and the glass/CeO{sub 2} pair. In vacuum, however, no discernable wear phenomena were observed, but the phase images captured by AFM tapping mode suggested the occurrence of potential strain hardening in the friction area of the glass surface.

Ion beam characterisation of nanometre structures

Energy Technology Data Exchange (ETDEWEB)

Persson, Leif

1995-08-01

Ion beam analysis methods have been applied to the study of technologically important issues in III-V nanometre structure science. In the first application, the incorporation of hydrogen in GaAs during electron cyclotron resonance etching was studied using the {sup 1}H({sup 15}N,{alpha}{gamma}){sup 12}C reaction analysis method. The major part of the work was carried out using mass and energy dispersive Recoil Spectrometry (RS). RS was used to study reactions of thin metal films InP reactions. The metals investigated include Cr, Ti, Ni, Pd and Pt and the reactions as a function of temperature were studied to elucidate suitable compounds for contacts and metallization. Using {sup 127}I in the 0.5A to 0.7A MeV region as the projectile, the depth profiles for the different elements were obtained. Complementary measurements with X-ray diffraction to obtain chemical phase information as well as scanning electron microscopy to study the surface morphology were also carried out. 59 refs, 15 figs.

Composition and sources of particles in Mannerheimintie during exceedance days of PM{sub 10} limit value in 2010; Hiukkasten koostumus ja laehteet Mannerheimintiellae PM{sub 10}-raja-arvon ylityspaeivinae 2010

Energy Technology Data Exchange (ETDEWEB)

Kupiainen, K.; Niemi, J.; Ritola, R.; Stojiljkovic, A.

2012-02-15

The purpose of the work was to determine sources of respirable particles (PM{sub 10}) in the center of Helsinki, at the measurement station in Mannerheimintie traffic site, in 2010 during the days when the daily average concentration of PM{sub 10} exceeded 50 mug/m3. By the end of the year (2010) the number of this kind of days was 24. The allowed number of exceedance days per year is 35, so the limit value was not exceeded in 2010. Similar work has been carried out in 2008 and 2009 and this report also summarizes results from all three years. HSY is responsible for monitoring the air quality in the Helsinki metropolitan area. The PM{sub 10} monitoring data in combination with electron microscopy based single particle compositional analysis and receptor modeling was used to evaluate dust source contributions on the exceedance days at HSY's air quality monitoring station in Mannerheimintie. According to the study the most significant source of PM{sub 10} particles in Mannerheimintie in 2010 was the dust sources related to traction control (winter-sanding and -salting of streets, pavement wear by studded tyres). Results from 2008 and 2009 show similar tendency. Also dust from construction sites contribute to airborne particle concentrations, timing of this source varies depending on the year. In 2010 particles from construction sites contributed to the exceedances that took place in late spring and early summer. Long-range transboundary air pollution also caused high concentrations of particles and contributed to some of the exceedances in 2008-2010. In late July and early August in 2010, long-range transboundary particles from the forest fires in Russia caused high particle concentrations in Helsinki metropolitan area and elsewhere in Southern Finland. Based on the results, the most significant means to reduce the airborne concentrations and to prevent the exceedance of the limit value are those that aim at mitigating street dust. In Helsinki, the means to

Assessment of Sub-Micron Particles by Exploiting Charge Differences with Dielectrophoresis

Directory of Open Access Journals (Sweden)

Maria F. Romero-Creel

2017-08-01

Full Text Available The analysis, separation, and enrichment of submicron particles are critical steps in many applications, ranging from bio-sensing to disease diagnostics. Microfluidic electrokinetic techniques, such as dielectrophoresis (DEP have proved to be excellent platforms for assessment of submicron particles. DEP is the motion of polarizable particles under the presence of a non-uniform electric field. In this work, the polarization and dielectrophoretic behavior of polystyrene particles with diameters ranging for 100 nm to 1 μm were studied employing microchannels for insulator based DEP (iDEP and low frequency (<1000 Hz AC and DC electric potentials. In particular, the effects of particle surface charge, in terms of magnitude and type of functionalization, were examined. It was found that the magnitude of particle surface charge has a significant impact on the polarization and dielectrophoretic response of the particles, allowing for successful particle assessment. Traditionally, charge differences are exploited employing electrophoretic techniques and particle separation is achieved by differential migration. The present study demonstrates that differences in the particle’s surface charge can also be exploited by means of iDEP; and that distinct types of nanoparticles can be identified by their polarization and dielectrophoretic behavior. These findings open the possibility for iDEP to be employed as a technique for the analysis of submicron biological particles, where subtle differences in surface charge could allow for rapid particle identification and separation.

One-component solution system to prepare nanometric anatase TiO2

International Nuclear Information System (INIS)

Trung, Tran; Ha, Chang-Sik

2004-01-01

A novel one-pot synthesis route was proposed to prepare nanometric anatase TiO 2 using trichloroethylene as reaction medium, which may have great advantage over multicomponent solution systems when TiO 2 is used as a reinforcing filler for polymers dissolved in trichloroethylene. The anatase TiO 2 nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy and small-angle X-ray scattering (SAXS). It was found that the diameters of TiO 2 nanoparticles are in the range from 5 to 13 nm

In situ laser measurements of CO and CH{sub 4} close to the surface of a burning single fuel particle

Energy Technology Data Exchange (ETDEWEB)

Lackner, M.; Totschnig, G.; Winter, F.; Maiorov, M.A.; Garbuzov, D.Z.; Connolly, J.C. [Vienna University of Technolgy, Vienna (Austria). Inst. of Chemical Engineering

2002-07-01

The combustion behaviour of three different fuels, bituminous coal, beech wood and fir wood, was investigated by monitoring the concentrations of CO, CH{sub 4}, CO{sub 2} and O{sub 2} during devolatilization and char combustion. Single fuel particles (4-6 mm diameter, 55 mm in length) were positioned in the freeboard of a laboratory-scale fluidized bed combustor. The superficial velocity was 0.3 m s{sup -1}. Tunable diode laser absorption spectroscopy was used to investigate in situ the concentration histories of the evolving species CO and CH{sub 4}. An InGaAsSb/AlGaAsSb diode laser was frequency tuned around 2.3/{mu}m at 300 Hz and traversed the reactor directly above the particle. This enabled the accurate measurement of species concentrations close to the surface of a burning particle. The influence of the oxygen partial pressure (5, 10, 15, 21 kPa), the bed temperature (700, 800, 900{sup o}C), the distance of the laser beam from the particle (4, 10, 21, 31 mm) and hence the residence time (12, 30, 60, 90 ms), the particle size (4, 6 {mu}m diameter) and the fuel type were investigated by independently changing these governing parameters. Conventional methods were deployed to determine CO, CO{sub 2} and O{sub 2} in the exhaust gas. The evolving CO could be tracked down to 12 ms after its generation. Biomass was found to produce four times as much CO as coal. The CO/CO{sub 2} ratio was found to be about five times higher for beech wood (a typical hardwood) than for fir wood (a typical softwood). The comparison of the in situ results with conventionally measured concentrations showed that the CO is normally underestimated during devolatilization and overestimated during char combustion. The discrepancy was attributed to more efficient degradation mechanisms for CO during devolatilization.

Path representation of su-hat (2){sub k} states I: Operators and particles for k=1,2

Energy Technology Data Exchange (ETDEWEB)

Lamy-Poirier, Joel, E-mail: jlamypoirier@perimeterinstitute.c [Departement de physique, de genie physique et d' optique, Universite Laval, Quebec, G1K 7P4 (Canada); Mathieu, Pierre, E-mail: pmathieu@phy.ulaval.c [Departement de physique, de genie physique et d' optique, Universite Laval, Quebec, G1K 7P4 (Canada)

2011-04-11

This is the first of two articles devoted to the analysis of the path description of the states in su-hat (2){sub k} WZW models, a representation well suited for constructive derivations of the fermionic characters. In this first article, the cases k=1,2 are treated in detail, emphasizing a different description in each case (operators vs particles). For k=1, we first prove, as a side result, the equivalence of two known path representations for the finitized su-hat (2){sub 1} states by displaying an explicit bijection. An immediate offshoot is the gain of a new and simple weighting for the (Kyoto) path representation that generalizes to level k. The bijection also suggests two operator constructions for the su-hat (2){sub 1} paths, a local and a nonlocal one, both interrelated. These are formal operators that map a path to another path, so that any path can be obtained by successive applications of these operators on a simple reference (ground-state) path. The nonlocal operator description is the starting point for a direct and elementary derivation of the su-hat (2){sub 1} spinon character. The second part presents an extensive study of the su-hat (2){sub 2} paths from their particle point of view, where the particles are defined as the path building blocks. The resulting generating functions appear to provide new (at least superficially) fermionic forms of the characters. In particular, a nice relationship between the sum of the j=0,1 characters at k=2 and the two ones at k=1 is unraveled.

A database of microwave and sub-millimetre ice particle single scattering properties

Science.gov (United States)

Ekelund, Robin; Eriksson, Patrick

2016-04-01

Ice crystal particles are today a large contributing factor as to why cold-type clouds such as cirrus remain a large uncertainty in global climate models and measurements. The reason for this is the complex and varied morphology in which ice particles appear, as compared to liquid droplets with an in general spheroidal shape, thus making the description of electromagnetic properties of ice particles more complicated. Single scattering properties of frozen hydrometers have traditionally been approximated by representing the particles as spheres using Mie theory. While such practices may work well in radio applications, where the size parameter of the particles is generally low, comparisons with measurements and simulations show that this assumption is insufficient when observing tropospheric cloud ice in the microwave or sub-millimetre regions. In order to assist the radiative transfer and remote sensing communities, a database of single scattering properties of semi-realistic particles is being produced. The data is being produced using DDA (Discrete Dipole Approximation) code which can treat arbitrarily shaped particles, and Tmatrix code for simpler shapes when found sufficiently accurate. The aim has been to mainly cover frequencies used by the upcoming ICI (Ice Cloud Imager) mission with launch in 2022. Examples of particles to be included are columns, plates, bullet rosettes, sector snowflakes and aggregates. The idea is to treat particles with good average optical properties with respect to the multitude of particles and aggregate types appearing in nature. The database will initially only cover macroscopically isotropic orientation, but will eventually also include horizontally aligned particles. Databases of DDA particles do already exist with varying accessibility. The goal of this database is to complement existing data. Regarding the distribution of the data, the plan is that the database shall be available in conjunction with the ARTS (Atmospheric

Tribological Properties of Nanometric Atomic Layer Depositions Applied on AISI 420 Stainless Steel

Directory of Open Access Journals (Sweden)

E. Marin

2013-09-01

Full Text Available Atomic Layer Deposition ( ALD is a modern technique that Allows to deposit nanometric, conformal coatings on almost any kind of substrates, from plastics to ceramic, metals or even composites. ALD coatings are not dependent on the morphology of the substrate and are only regulated by the composition of the precursors, the chamber temperature and the number of cycles. In this work, mono- and bi -layer nanometric, protective low-temperature ALD Coatings, based on Al2O3 and TiO2 were applied on AISI 420 Stainless Steel in orderto enhance its relatively low corrosion resistance in chloride containing environments. Tribological testing were also performed on the ALD coated AISI 420 in order to evaluate the wear and scratch resistance of these nanometric layers and thus evaluate their durability. Scratch tests were performed using a standard Rockwell C indenter, under a variable load condition, in order to evaluate the critical loading condition for each coating. Wear testing were performed using a stainless steel counterpart, in ball-on-discconfiguration, in order to measure the friction coefficient and wear to confront the resistance. All scratch tests scars and wear tracks were then observed by means of Scanning Electron Microscopy (SEM in order to understand the wear mechanisms that occurred on the sample surfaces. Corrosion testing, performed under immersion in 0.2 M NaCl solutions, clearly showed that the ALD coatings have a strong effect in protecting the Stainless Steel Substrate against corrosion, reducing the corrosion current density by two orders of magnitude.Tribological The preliminary results showed that ALD depositions obtained at low Temperatures have a brittle behavior caused by the amorphous nature of their structure, and thus undergo delamination phenomena during Scratch Testing at relatively low applied loads. During ball-on-disc testing, the coatings were removed from the substrate, in particular for monolayer ALD configurations

PROPRIEDADES E AVALIAÇÃO CATALÍTICA DA ZEÓLITA X NANOMÉTRICA CONTENDO CÁTIONS METILAMÔNIO

Directory of Open Access Journals (Sweden)

João G. P. Vicente

2016-07-01

Full Text Available The reduction of zeolite particle is one of the main features currently searched; it is due to the catalytic gains that these materials come in some reactions. In this work two faujasite zeolites of type X were evaluated, a micrometer and nanometric. Zeolites in sodium form were exchanged ionically with methylammonium cations. These materials were evaluated as catalysts in the Knoevenagel condensation reaction. Steric impediments restricted the ion exchange in the micrometer zeolite and have become more predominant due to the increase in the volume of cations. In nanometric sample such impediments were less evident due to the reduction of the particles provide greater accessibility to exchangers cations to inaccessible sodium in micrometer zeolite. The best catalytic performances were achieved with zeolites containing the monomethylammonium cation. The increased of the accessibility and diffusion of the reactants and products through the pores of the nanometric zeolite provided the best butyraldehyde conversions independent the exchanger cation

Synthesis and characterization of α-alumina col-gel nanometric: elaboration of biomaterials nanostructured for biomedical applications

International Nuclear Information System (INIS)

Passoni, L.S.; Feit, G.; Camargo, N.H.A.

2010-01-01

The production of nanostructured biomaterials are research themes for these present new characteristics of biocompatibility and bioactivity. The sol-gel process allows obtaining α-alumina nanometric with purity 99.99%. The use of nanoparticles of Al 2 O 3 -α, SiO 2 and TiO 2 are being employed as a second stage in the development of nanocomposites biomaterials. The presence of the second phase within a ceramic matrix leads to obtaining nanomaterials with micropores in micro and nanostructures interconnected, what contributes within the processes of osseous integration, osseous induction. The goal of this work focused on synthesis and characterization of an α- alumina by sol-gel process. Characterization studies were conducted using the various techniques: X-ray diffraction, scanning electron microscopy, exploratory differential scanning calorimetry and infrared spectrometry by Fourier transforms. The preliminary results showed the attainment the nanometric α-alumina powder. (author)

Status of a study of stabilization and fine positioning of CLIC quadrupoles to the nanometre level

CERN Document Server

Artoos, K; Esposito, M; Fernandez Carmona, P; Guinchard, M; Hauviller, C; Janssens, S; Kuzmin, A; Leuxe, R; Moron Ballester, R

2011-01-01

Mechanical stability to the nanometre and below is required for the Compact Linear Collider (CLIC) quadrupoles to frequencies as low as 1 Hz. An active stabilization and positioning system based on very stiff piezo electric actuators and inertial reference masses is under study for the Main Beam Quadrupoles (MBQ). The stiff support was selected for robustness against direct forces and for the option of incrementally repositioning the magnet with nanometre resolution. The technical feasibility was demonstrated by a representative test mass being stabilized and repositioned to the required level in the vertical and lateral direction. Technical issues were identified and the development programme of the support, sensors, and controller was continued to increase the performance, integrate the system in the overall controller, adapt to the accelerator environment, and reduce costs. The improvements are implemented in models, test benches, and design of the first stabilized prototype CLIC magnet. The characterizati...

Effect of calcination temperature on the H{sub 2}O{sub 2} decomposition activity of nano-crystalline Co{sub 3}O{sub 4} prepared by combustion method

Energy Technology Data Exchange (ETDEWEB)

Makhlouf, M.Th. [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Abu-Zied, B.M., E-mail: babuzied@aun.edu.eg [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Mansoure, T.H. [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt)

2013-06-01

Cobalt oxide nano-particles were prepared by combustion method using urea as a combustion fuel. The effects of calcination temperature, 350–1000 °C, on the physicochemical, surface and catalytic properties of the prepared Co{sub 3}O{sub 4} nano-particles were studied. The products were characterized by thermal analyses (TGA and DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Textural features of the obtained catalysts were investigated using nitrogen adsorption at −196 °C. X-ray diffraction confirmed that the resulting oxide was pure single-crystalline Co{sub 3}O{sub 4} nano-particles. Transmission electron microscopy indicating that, the crystallite size of Co{sub 3}O{sub 4} nano-crystals was in the range of 8–34 nm. The catalytic activities of prepared nano-crystalline Co{sub 3}O{sub 4} catalysts were tested for H{sub 2}O{sub 2} decomposition at 35–50 °C temperature range. Experimental results revealed that, the catalytic decomposition of H{sub 2}O{sub 2} decreases with increasing the calcination temperature. This was correlated with the observed particle size increase accompanying the calcination temperature rise.

Enhanced field emission characteristics of boron doped diamond films grown by microwave plasma assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Koinkar, Pankaj M. [Center for International Cooperation in Engineering Education (CICEE), University of Tokushima, 2-1 Minami-josanjima-cho, Tokushima 770-8506 (Japan); Patil, Sandip S. [Center for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411007 (India); Kim, Tae-Gyu [Department of Nano System and Process Engineering, Pusan National University, 50 Cheonghak-ri, Samrangjin-eup, Miryang, Gyeongnam, Pusan 627-706 (Korea, Republic of); Yonekura, Daisuke [Department of Mechanical Engineering, University of Tokushima, 2-1 Minami-josanjima-cho, Tokushima 770-8506 (Japan); More, Mahendra A., E-mail: mam@physics.unipune.ac.in [Center for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411007 (India); Joag, Dilip S. [Center for Advanced Studies in Materials Science and Condensed Matter Physics, Department of Physics, University of Pune, Pune 411007 (India); Murakami, Ri-ichi, E-mail: murakami@me.tokushima-u.ac.jp [Department of Mechanical Engineering, University of Tokushima, 2-1 Minami-josanjima-cho, Tokushima 770-8506 (Japan)

2011-01-01

Boron doped diamond films were synthesized on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) technique. The effect of B{sub 2}O{sub 3} concentration varied from 1000 to 5000 ppm on the field emission characteristics was examined. The surface morphology and quality of films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. The surface morphology obtained by SEM showed variation from facetted microcrystal covered with nanometric grains to cauliflower of nanocrystalline diamond (NCD) particles with increasing B{sub 2}O{sub 3} concentration. The Raman spectra confirm the formation of NCD films. The field emission properties of NCD films were observed to improve upon increasing boron concentration. The values of the onset field and threshold field are observed to be as low as 0.36 and 0.08 V/{mu}m, respectively. The field emission current stability investigated at the preset value of {approx}1 {mu}A is observed to be good, in each case. The enhanced field emission properties are attributed to the better electrical conductivity coupled with the nanometric features of the diamond films.

Chemical synthesis of Fe/Fe{sub 3}O{sub 4} core-shell composites with enhanced soft magnetic performances

Energy Technology Data Exchange (ETDEWEB)

Yang, Bai, E-mail: byang@buaa.edu.cn [Key Laboratory of Aerospace Advanced Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Xiaopan [Key Laboratory of Aerospace Advanced Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Yang, Xueying [Hi-tech Industry Standardization Institute, Hubei Standardization and Quality Institution, Wuhan 430061 (China); Yu, Ronghai [Key Laboratory of Aerospace Advanced Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2017-04-15

The large-grain Fe/Fe{sub 3}O{sub 4} composite particles with average size of about 1.2 µm have been fabricated by a facile one-step solvothermal method. The formation of high-purity Fe{sub 3}O{sub 4} as the shells (90.14 wt%) and α-Fe as the cores (9.86 wt%) in the Fe/Fe{sub 3}O{sub 4} composites leads to their high saturation magnetization of 119.6 A m{sup 2} Kg{sup -1}. Very low coercivity of 30 Oe is obtained in the composites due to their uniform cubic-shaped morphologies. Compared with Fe-based nanosized particles, these micron-sized magnetic Fe/Fe{sub 3}O{sub 4} composites exhibit high air stability and good compactibility with high compressed density of 5.9 g cm{sup -3}. The fully compacted sample shows good soft magnetic properties including high magnetic induction B{sub 1.2k} {sub (H=1200} {sub A/m)} of 540 mT and good frequency-dependent magnetic properties with operating frequency up to 50 MHz superior to those of the most traditional soft magnetic ferrites, which promotes their potential applications in high-frequency and high-power magnetic devices. - Highlights: • Micron-sized Fe/Fe{sub 3}O{sub 4} composites are prepared by a one-step solvothermal method. • High saturation magnetization and low coercivity are obtained in the composites. • Good air stability and high bulk density occurs in the composites. • High magnetic induction and good frequency-dependent properties are achieved.

Quantum gravity phenomenology. Achievements and challenges

Energy Technology Data Exchange (ETDEWEB)

Liberati, S. [International School for Advanced Study (SISSA), Trieste (Italy); INFN, Sezione di Trieste (Italy); Maccione, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2011-05-15

Motivated by scenarios of quantum gravity, Planck-suppressed deviations from Lorentz invariance are expected at observable energies. Ultra-High-Energy Cosmic Rays, the most energetic particles ever observed in nature, yielded in the last two years strong constraints on deviations suppressed by O(E{sup 2}/M{sup 2}{sub Pl}) and also, for the first time, on space-time foam, stringy inspired models of quantum gravity. We review the most important achievements and discuss future outlooks. (orig.)

Effect of temperature on structural, morphological and magnetic properties of Cd{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Prabhakar Vattikuti, S.V., E-mail: vsvprabu@gmail.com [School of Mechanical Engineering, Yeungnam University, Gyeongsan, Gyeongsangbuk-do 712-749, Republic of Korea, (Korea, Republic of); Byon, Chan [School of Mechanical Engineering, Yeungnam University, Gyeongsan, Gyeongsangbuk-do 712-749, Republic of Korea, (Korea, Republic of); Shim, Jaesool, E-mail: jshim@ynu.ac.kr [School of Mechanical Engineering, Yeungnam University, Gyeongsan, Gyeongsangbuk-do 712-749, Republic of Korea, (Korea, Republic of); Reddy, Ch. Venkata, E-mail: cvrphy@gmail.com [School of Mechanical Engineering, Yeungnam University, Gyeongsan, Gyeongsangbuk-do 712-749, Republic of Korea, (Korea, Republic of)

2015-11-01

Cadmium-substituted cobalt ferrite (Cd{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4}) nanoparticles were synthesized using a chemical synthesis method and synthesized particles were calcinated at 300 °C and 600 °C respectively. The samples were characterized in order to understand the temperature effect on structural, morphological, thermal, and magnetic properties. X-ray diffraction data confirm the formation of single-phase cubic structure and the average grain sizes were evaluated. The microstructural features were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and compositional analysis carried out by energy dispersive spectroscopy (EDS). A vibrating sample magnetometer (VSM) was used to investigate the magnetic properties. The hysteresis curves of Cd{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4} nanoparticles show enhancement of the coercivity with the increasing calcinated temperature. This enhancement is attributed to the transition from a multi-domain to a single-domain nature. The high and low frequency absorption bands of Cd{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4} were investigated using FT-IR analysis. - Highlights: • Cd{sub 0.7}Co{sub 0.3}Fe{sub 2}O{sub 4} nano particles are prepared by the chemical synthesis method. • X-ray diffraction data confirms the single phase cubic spinel structure. • The estimated particle sizes from the XRD are approximately 25 and 35 nm. • The coercivity and magnetization values increase with increasing the particle size. • FT-IR spectra indicate the fundamental vibrations of host lattices.

Can reduced size of metals induce hydrogen absorption: ZrAl{sub 2} case

Energy Technology Data Exchange (ETDEWEB)

Jacob, I., E-mail: izi@bgu.ac.il [Department of Nuclear Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Deledda, S. [Physics Department, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Bereznitsky, M. [Department of Nuclear Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Yeheskel, O. [Nuclear Research Center - Negev, P.O. Box 9001, Beer Sheva 84190 (Israel); Filipek, S.M. [Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw (Poland); Mogilyanski, D.; Kimmel, G. [Institute for Applied Research, P.O. Box 653, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel); Hauback, B.C. [Physics Department, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway)

2011-09-15

Research highlights: > 15 nm particles of ZrAl{sub 2} and Zr(Al{sub 0.5}Co{sub 0.5}){sub 2} are obtained by attrition and cryomilling. > ZrAl{sub 2} nanoparticles remain inert to hydrogen absorption up to pressure of {approx}2 GPa. > Zr(Al{sub 0.5}Co{sub 0.5}){sub 2} nanoparticles exhibit reduced hydrogen absorption as compared to the corresponding bulk compounds. - Abstract: The hydrogen absorption ability of the non-absorbing Al-rich ZrAl{sub 2} compound was examined after reducing its particles-size to the nanometer regime. The hydrogen abstinence of bulk ZrAl{sub 2} has been previously related to its excessive elastic shear stiffening. The particle size of ZrAl{sub 2} was reduced by attrition milling and cryomilling. The minimal average particle size was estimated from powder X-ray diffraction analysis to be in the range of 10-20 nm. The hydrogen absorption of the milled compounds was measured in different hydrogenation systems at hydrogen pressures between {approx}6 MPa and {approx}2 GPa. In all the cases the hydrogen absorption was negligible. In addition, there was a reduction of the hydrogen absorption capacity of nanosized Zr(Al{sub 0.5}Co{sub 0.5}){sub 2} as compared to the corresponding bulk compound at the same conditions. We suggest, in view of our and other results, that no significant improvement of the thermodynamics (unlike the kinetics) of the hydrogen absorption can be achieved via the nanoparticle avenue.

Evidence of magnetic dipolar interaction in micrometric powders of the Fe{sub 50}Mn{sub 10}Al{sub 40} system: Melted alloys

Energy Technology Data Exchange (ETDEWEB)

Perez Alcazar, G.A., E-mail: gpgeperez@gmail.com [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Zamora, L.E. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Tabares, J.A.; Piamba, J.F. [Departamento de Fisica, Universidad del Valle, A. A. 25360, Cali (Colombia); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, Apdo. 155, 28230 Las Rozas, Madrid (Spain); Greneche, J.M. [LUNAM, Universite du Maine, Institut des Molecules et Materiaux du Mans, UMR CNRS 6283, 72085 Le Mans Cedex 9 (France); Martinez, A. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Las Rozas (Spain); Romero, J.J. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain); Marco, J.F. [Instituto de Quimica Fisica Rocasolano, CSIC, C/Serrano 119, 28006 Madrid (Spain)

2013-02-15

Powders of melted disordered Fe{sub 50}Mn{sub 10}Al{sub 40} alloy were separated at different mean particle sizes as well as magnetically and structurally characterized. All the samples are BCC and show the same nanostructure. Particles larger than 250 {mu}m showed a lamellar shape compared to smaller particles, which exhibited a more regular form. All the samples are ferromagnetic at room temperature and showed reentrant spin-glass (RSG) and superparamagnetic (SP)-like behaviors between 30 and 60 K and 265 and > 280 K, respectively, as a function of frequency and particle size. The freezing temperature increases with increasing particle size while the blocking one decreases with particle size. The origin of these magnetic phenomena relies in the internal disordered character of samples and the competitive interaction of Fe and Mn atoms. The increase of their critical freezing temperature with increasing mean particle size is due to the increase of the magnetic dipolar interaction between the magnetic moment of each particle with the field produced by the other magnetic moments of their surrounding particles. - Highlights: Black-Right-Pointing-Pointer The effect of particle size in microsized powders of Fe{sub 50}Mn{sub 10}Al{sub 40} melted disordered alloy is studied. Black-Right-Pointing-Pointer Dipolar magnetic interaction between particles exists and this changes with the particle size. Black-Right-Pointing-Pointer For all the particle sizes the reentrant spin- glass and the superparamagnetic-like phases exist. Black-Right-Pointing-Pointer RSG and SP critical temperatures increase with increasing the dipolar magnetic interaction (the mean particle size).

Status of PACMAN Project at CERN

CERN Document Server

Catalan-Lasheras, Nuria; Modena , Michele

2015-01-01

Though the Large Hadron Collider (LHC) at CERN is just at the start of a program expected to run for 20 additional years, CERN is studying the next generation of colliders, like the Compact Linear Collider (CLIC). This project proposes an electron-positron collider with a length close to 50 km and with a centre of mass energy of 3 TeV at the collision point. One of the main challenges is the sub-micrometric size of the beams, down to a few nanometres at the interaction point. As a consequence, the accelerator will require unprecedented nanometric tolerances of beam alignment. A series of several thousands components will have to be assembled, aligned at the micrometre level and most critically, stabilized actively at the nanometre level. PACMAN, a study on Particle Accelerator Components Metrology and Alignment to the Nanometre scale, is a Marie Curie Program supported by the European Commission (FP7 Program), creating a network of 16 Academic and Industrial Partners. The project is hosted at CERN and it offe...

Communication of Information with Sub-particles (Sub-strings) from Fifth Dimension of the Universe (Information) as the "Fundamental Symmetry" in the Nature

Science.gov (United States)

Gholibeigian, Hassan; Gholibeigian, Ghsem; Amirshahkarami, Abdolazim; Gholibeigian, Kazem

2016-11-01

All fundamental particles (strings) getting information from their four animated sub-particles (sub-strings) after processing by them for motion. It seems that the source of information which particles and dark mater/energy are floating in it and whispering to its communication may be "fifth dimension" of the nature after space-time dimensions. In other words, the space-time can be the universe's hardware and information's dimension can be dynamic software of the universe which has always become up to date. Communication of information has a vital role in creation and evolution of the universe, may be as the "fundamental symmetry" in the nature, which began before the spark to B.B. (Convection Bang), and leads other symmetries and supersymmetry as well as other phenomena. Duration of the before Planck time, from 0 ->10-44 second, and its correspondence space which its result was generation of the very hot and energetic point for the B.B. / C.B. needed to communication of information. It seems that this fifth dimension has appeared for leading the processes before and after Planck time. How this dimension of the nature appeared and has always become up to date? AmirKabir University of Technology, Tehran, Iran.

High-temperature mechanical properties and fracture mechanisms of Al–Si piston alloy reinforced with in situ TiB{sub 2} particles

Energy Technology Data Exchange (ETDEWEB)

Han, Gang [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Weizheng, E-mail: zhangwz@bit.edu.cn [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Guohua; Feng, Zengjian; Wang, Yanjun [Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602 (China)

2015-05-01

In order to assess the high-temperature performance of aluminum–silicon alloy reinforced with titanium diboride particles as potential piston material, the tensile behaviors and fracture mechanisms of in situ 4 wt% TiB{sub 2}/Al–Si composite were investigated in the temperature range 25–350 °C. The tensile results revealed that the composite exhibited higher modulus than the matrix alloy at all testing temperatures, but both the matrix alloy and the composite presented similar strength levels above 200 °C. The ductility of the composite was found to be lower than that of the unreinforced matrix alloy at 25 and 200 °C, but no obvious distinction was observed at 350 °C. The effects of temperature and the presence of TiB{sub 2} particles on tensile properties of the composite had been evaluated. Fractographic morphology studies were done using scanning electron microscope, which indicated that the fracture of the composite altered from brittle to ductile mode with temperature increasing. At 25 and 200 °C, fracture was dominated by cracked silicon particles and separated TiB{sub 2} particles, while decohesion at particle–matrix interface was prevalent at 350 °C. Analysis of the fracture surfaces also showed that regions of clustered TiB{sub 2} particles were found to be the locations prone to damage in the composite at both room and high temperatures.

Functional nanometers for hydrogen storage produced by ball milling

Energy Technology Data Exchange (ETDEWEB)

Czujko, T. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering]|[Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies; Varin, R.A. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering; Wronski, Z.S. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre, Hydrogen Fuel Cells and Transportation; Zaranski, Z. [Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies

2008-07-01

It is becoming increasingly important to switch to cleaner alternative energy carriers such as hydrogen, as environmental concerns over greenhouse gas emissions from the burning of fossil fuel increase. Specifically, there is a need for efficient on-board hydrogen storage technologies for vehicular applications. This paper discussed three different methods of hydrogen desorption temperature reduction and desorption kinetics of nanostructured hydrides. The first method was based on substantial hydride particle size refinement. The second method utilized catalytic effects of nanometric n-alumina (Al{sub 2}O{sub 3}), n-yttrium oxide powder (Y{sub 2}O{sub 3}) and n-nickel (Ni) additives. The third method was based on a composite of nanohydride mixtures. The composite approach was applied to the magnesium hydride (MgH{sub 2}) plus sodium tetrahydridoborate (NaBH{sub 4}) and lithium aluminum hydride (LiAlH{sub 4}) systems. The paper presented the effects of nanostructuring and nanocatalytic additives on Mg hydride desorption properties as well as a composite behaviour of nanostructured complex hydrides. It was concluded that milling of commercial MgH{sub 2} with the nano-oxide additives had a limited effect on improving the hydrogen storage properties. The addition of specialty Inco nanometric Ni reduced the hydrogen desorption temperature considerably. 28 refs., 1 tab., 9 figs.

Contribution of road traffic to ambient fine particle concentrations (PM{sub 10}) in Switzerland

Energy Technology Data Exchange (ETDEWEB)

Hueglin, Ch.; Devos, W.; Gehrig, R.; Hofer, P.; Kobler, J. [Swiss Federal Laboratoires for Materials Testing and Research, EMPA, Dubendorf (Switzerland); Stahel, W.A. [Seminar for Statistics, ETH Zurich (Switzerland); Baltensperger, U. [Paul Scherrer Institute, Villigen PSI (Switzerland); Monn, Ch. [Institute for Hygiene and Applied Physiology, ETH Zurich (Switzerland)

2000-07-01

A multivariate receptor model was applied to estimate the contribution of road traffic to ambient levels of fine particles (PM{sub 10}) at different locations in Switzerland. At two roadside sites with heavy local traffic, the road traffic was found to account for 46% and 64% of PM{sub 10}. At an urban background site, the estimated average road traffic contribution was 34%, whereas a slightly higher value was obtained at a suburban site (36%). This results are in good agreement with the findings of a recent study, where a conceptually different approach (dispersion modelling) was applied. (authors)

Sub-surface microstructure of single and polycrystalline tungsten after high flux plasma exposure studied by TEM

Energy Technology Data Exchange (ETDEWEB)

Dubinko, A., E-mail: adubinko@sckcen.be [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Terentyev, D. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Bakaeva, A. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Hernández-Mayoral, M. [Division of Materials, CIEMAT, 28040 Madrid (Spain); De Temmerman, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul-lez-Durance Cedex (France); Buzi, L. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany); Noterdaeme, J.-M. [Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Unterberg, B. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany)

2017-01-30

Highlights: • Plasma exposure induces dislocation-dominated microstructure as indicated by TEM. • Plasma exposure increases surface dislocation density by an order of magnitude in the polycrystalline tungsten. • Intensive dislocation-grain boundary interaction observed in polycrystalline tungsten. • Dislocation loops are observed in both polycrystalline and single crystal tungsten. - Abstract: We have performed high flux plasma exposure of tungsten and subsequent microstructural characterization using transmission electron microscopy (TEM) techniques. The aim was to reveal the nanometric features in the sub-surface region as well as to compare the microstructural evolution in tungsten single crystal and ITER-relevant specification. In both types of samples, TEM examination revealed the formation of a dense dislocation network and dislocation tangles. The estimated dislocation density in the sub-surface region was of the order of 10{sup 14} m{sup −2} and it gradually decreased with a depth position of the examined sample. Besides individual dislocation lines, networks and tangles, the interstitial dislocation loops have been observed in all examined samples only after the exposure. Contrary to that, examination of the pristine single crystal W and backside of the plasma-exposed samples did not reveal the presence of dislocation loops and tangles. This clearly proves that high flux plasma exposure induces severe plastic deformation in the sub-surface region irrespective of the presence of initial dislocations and sub-grains, and the formation of dislocation tangles, networks and interstitial loops is a co-product of thermal stress and intensive plasma particles uptake.

First-principles quantum molecular calculations of structural and mechanical properties of TiN/SiN{sub x} heterostructures, and the achievable hardness of the nc-TiN/SiN{sub x} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Ivashchenko, V.I., E-mail: ivash@ipms.kiev.ua [Institute of Problems of Material Science, National Academy of Science of Ukraine, Krzhyzhanosky Str. 3, 03142 Kyiv (Ukraine); Veprek, S., E-mail: stan.veprek@lrz.tum.de [Department of Chemistry, Technical University Munich, Lichtenbergstrasse 4, D-85747 Garching (Germany); Argon, A.S. [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Turchi, P.E.A. [Lawrence Livermore National Laboratory (L-352), P.O. Box 808, Livermore, CA 94551 (United States); Gorb, L. [Badger Technical Services, LLC, Vicksburg, MS 39180 (United States); U.S. Army ERDC, Vicksburg, MS 39180 (United States); Hill, F. [U.S. Army ERDC, Vicksburg, MS 39180 (United States); Leszczynski, J. [Department of Chemistry and Biochemistry, Interdisciplinary Center for Nanotoxicity, Jackson State University, Jackson, MS 39217 (United States)

2015-03-02

TiN/SiN{sub x} heterostructures with one monolayer of the interfacial SiN{sub x} have been investigated in the framework of first-principles molecular dynamics calculations in the temperature range of 0 to 1400 K with subsequent static relaxation. The atomic configurations, thermal stability and stress–strain relations have been calculated. Among the heterostructures studied, only the TiN(111)/SiN/TiN(111) and TiN(111)/Si{sub 2}N{sub 3}/TiN(111) ones are thermally stable. Upon tensile load, decohesion occurs between the Ti−N bonds adjacent to the SiN{sub x} interfacial layer for TiN(001)/SiN/TiN(001) and TiN(111)/Si{sub 2}N{sub 3}/TiN(111) heterostructures, and inside the TiN slab for TiN(001)/Si{sub 3}N{sub 4}/TiN(001) and TiN(110)/SiN/TiN(110) ones. Upon shear, failure occurs in TiN near the interfaces in all the heterostructures, except for the TiN(001)/Si{sub 3}N{sub 4}/TiN(001) one, for which the plastic flow occurs inside the TiN slab. Based on these results we estimate the maximum achievable hardness of nc-TiN/Si{sub 3}N{sub 4} nanocomposites free of impurities to be about 170 GPa. - Highlights: • Interface stability in TiN/SiN{sub x} heterostructures at T ≤ 1400 K is studied by quantum molecular dynamics. • Ideal decohesion and shear strengths of the heterostructures have been calculated. • Achievable hardness of nc-TiN/Si{sub 3}N{sub 4}-like nanocomposites of about 170 GPa is calculated. • Experimentally achieved lower hardness is limited by flaws, such as oxygen impurities.

Evaluation of luminescent properties and detection of Eu{sup 2}+ in nano structured particles of Gd{sub 2}-x Eu{sub x}O{sub 3} system (x= 0.05, 0.10 and 0.30); Evaluacion de las propiedades luminiscentes y deteccion de Eu{sup 2}+ en particulas nanoestructuradas del sistema Gd{sub 2}-xEu{sub x} O{sub 3} (x= 0.05, 0.10 y 0.30)

Energy Technology Data Exchange (ETDEWEB)

Barroso, J.; Mena, I.; Gomez, L. S.; Milosevic, O.; Rabanal, M. E.

2012-11-01

Spray Pyrolysis (SP) is performed at 700 degree centigrade in dry air atmosphere using common nitrate aqueous solutions (0,1M) as precursor in order to obtain nano structured particles with the composition Gd{sub 2}-xEu{sub x}O{sub 3} (x= 0.05, 0.10 and 0.30). In this work, three samples with different atomic europium concentration (1, 2 and 6%) were studied. After, the obtained particles were subjected to different thermal treatments with varying temperatures between 800 and 1000 degree centigrade/12 h in dry air atmosphere. The obtained particles were characterized by XRD, SEM techniques, laser dispersion and steady state fluorescence spectroscopy. The existence of two cubic phases with different symmetry cubic phases (Ia-3, Fm-3m) was identified within the as-prepared samples. Moreover, the presence of Gd{sub 2}O{sub 3} monoclinic phase (C{sub 2}/m) which disappears during the thermal treatments was proved. In all thermally treated samples, it was observed the stabilization of an only Ia-3 phase. Fluorescence emission measurements in all studied samples the presence of Eu{sup 2}+ ({lambda}= 430nm), whose intensity increases as long as the content of the monoclinic phase decreases of the Eu{sup 3}+ percentage. (Author) 35 refs.

Monodispersed MnO nanoparticles with epitaxial Mn{sub 3}O{sub 4} shells

Energy Technology Data Exchange (ETDEWEB)

Berkowitz, A E; Rodriguez, G F [Department of Physics, University of California, San Diego La Jolla, CA 92093 (United States); Hong, J I; Fullerton, E E [Center for Magnetic Recording Research, University of California-San Diego La Jolla, CA 92093 (United States); An, K; Hyeon, T [National Creative Research Initiative Center for Oxide Nanocrystalline Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Agarwal, N; Smith, D J [School of Materials and Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2008-07-07

We report the microstructural and magnetic properties of monodispersed nanoparticles (NPs) of antiferromagnetic MnO (T{sub N} = 118 K), with epitaxial ferrimagnetic Mn{sub 3}O{sub 4} (T{sub C} = 43 K) shells. Above T{sub C}, an unusually large magnetization is present, produced by the uncompensated spins (UCSs) on the surface of the MnO particles. These spins impart a net anisotropy to the MnO particles that is approximately three orders of magnitude larger than the bulk value. As a result, an anomalously high blocking temperature is exhibited by the MnO particles, and finite coercivity and exchange bias are present above T{sub C}. When field cooled below T{sub C}, a strong exchange bias was established in the Mn{sub 3}O{sub 4} shells as a result of high net anisotropy of the MnO particles. A large coercivity was also observed. Models of several aspects of the behaviour of this unusual system emphasized the essential role of the UCSs on the surfaces of the MnO NPs.

Characterization and thermal behavior of PrMO{sub 3} (M = Co or Ni) ceramic materials obtained from gelatin

Energy Technology Data Exchange (ETDEWEB)

Aquino, F.M., E-mail: flavyma@hotmail.com [Federal University of Rio Grande of Norte, Laboratory of Catalysis and Refining – NUPRAR, Av. Senador Salgado Filho, 3000, CEP 59078-970, Natal-RN (Brazil); Melo, D.M.A. [Federal University of Rio Grande of Norte, Laboratory of Catalysis and Refining – NUPRAR, Av. Senador Salgado Filho, 3000, CEP 59078-970, Natal-RN (Brazil); Pimentel, P.M. [Universidade Federal Rural do Semi-Árido, Campus Angicos, CEP 59515-000, Angicos-RN (Brazil); Braga, R.M.; Melo, M.A.F.; Martinelli, A.E.; Costa, A.F. [Federal University of Rio Grande of Norte, Laboratory of Catalysis and Refining – NUPRAR, Av. Senador Salgado Filho, 3000, CEP 59078-970, Natal-RN (Brazil)

2012-09-15

Graphical abstract: The micrograph in figure shows sample calcined at temperature 900 °C. The sample exhibits morphology with considerable porosity and the formation of agglomerated nanometric particles. Gelatin provides the system with a large amount of organic matter, which is then removed during calcinations, favoring the appearance of pores in the material. Highlights: ► Oxides with PrNiO{sub 3} and PrCoO{sub 3} were prepared by new method synthesis. ► The gelatin, through its carboxylate groups and amine, is an efficient director. ► The obtained materials have magnetic properties and application in catalysis. ► The decomposition kinetic study of bonding groups of gelatin with metallic ions that takes part in the synthesis of PrMO{sub 3}. -- Abstract: Metal oxides with perovskite-type structure have attracted considerable interest in recent years due to their magnetic and electrical properties, as well as their catalytic activity. In this study, oxides with PrNiO{sub 3} and PrCoO{sub 3} composition were prepared by using gelatin powder as a precursor agent for its use as a catalyst. The powders obtained were calcined at 700 °C and 900 °C and characterized using the X-ray diffraction, thermal analysis (thermogravimetry and differential thermal analysis), infrared spectroscopy, temperature programed reduction and scanning electron microscopy techniques. Thermogravimetric data using the non-isothermal kinetic models of Flynn and Wall and “Model-free Kinetics” were used to determine the activation energy to study the decomposition kinetics of the ligand groups with system's metallic ions that takes part in the synthesis of PrMO{sub 3} (M = Ni or Co).

Contribution to the study of second phases particles dispersion in polycrystalline uranium dioxide

International Nuclear Information System (INIS)

Peres, V.

1994-06-01

To reduce fission gas release of irradiated polycrystalline uranium dioxide, the dispersion of intragranular nanometric particles of second phase necessary to pin gas bubbles may complete the advantage of a large-grained fuel microstructure. Moreover, intergranular glass films may improve high temperatures mechanical properties of UO 2 . In this study, mixtures of additives composed of ''corindon'' structure oxides that enhance the fuel grain growth and composed of different oxides with variable solid solubilities in the UO 2 matrix were achieved. Additives with a negligible solubility inhibit grain boundaries motion except those, such as silica, that involve a liquid phase at the sintering temperature. Rare earth oxides that form stable solid solutions with UO 2 cannot lead to precipitation, but have no effect on the fuel grain growth doped with ''corindon'' type oxides. A chromium oxide excess allows the creation of a fuel microstructure described by large grains and intragranular spherical Cr 2 O 3 inclusions observed by scanning electron microscopy. Values for the bulk lattice diffusion coefficient of Cr 3+ cations in UO 2 can be deduced from the experimental growth of those dispersed particles by an Ostwald ripening mechanism. The formation of small precipitated metal particles inside the uranium dioxide matrix induced by the internal reduction of a solid solution has not been performed. However, direct reduction of insoluble chromium oxide particles is easy and produces metallic intragranular precipitates. (author). 119 refs., 112 figs., 33 tabs., 5 annexes

Non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} on dehydrogenation high-energy ball milled MgH{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Zhang, Tiebang, E-mail: tiebangzhang@nwpu.edu.cn; Hou, Xiaojiang; Hu, Rui; Kou, Hongchao; Li, Jinshan

2016-11-01

MgH{sub 2}-M (M = TiF{sub 3} or Nb{sub 2}O{sub 5} or both of them) composites prepared by high-energy ball milling are used in this work to illustrate the dehydrogenation behavior of MgH{sub 2} with the addition of catalysts. The phase compositions, microstructures, particle morphologies and distributions of MgH{sub 2} with catalysts have been evaluated. The non-isothermal synergetic catalytic-dehydrogenation effect of TiF{sub 3} and Nb{sub 2}O{sub 5} evaluated by differential scanning calorimetry gives the evidences that the addition of catalysts is an effective strategy to destabilize MgH{sub 2} and reduce hydrogen desorption temperatures and activation energies. Depending on additives, the desorption peak temperatures of catalyzed MgH{sub 2} reduce from 417 °C to 341 °C for TiF{sub 3} and from 417 °C to 336 °C for Nb{sub 2}O{sub 5}, respectively. The desorption peak temperature reaches as low as 310 °C for MgH{sub 2} catalyzed by TiF{sub 3} coupling with Nb{sub 2}O{sub 5}. The non-isothermal synergetic catalytic effect of TiF{sub 3} and Nb{sub 2}O{sub 5} is mainly attributed to electronic exchange reactions with hydrogen molecules, which improve the recombination of hydrogen atoms during dehydrogenation process of MgH{sub 2}. - Highlights: • Catalytic surface for MgH{sub 2} is achieved by high-energy ball milling. • Non-isothermal dehydrogenation behavior of MgH{sub 2} with TiF{sub 3} and/or Nb{sub 2}O{sub 5} is illustrated. • Dehydrogenation activation energies of synergetic catalyzed MgH{sub 2} are obtained. • Synergetic catalytic-dehydrogenation mechanism of TiF{sub 3} and Nb{sub 2}O{sub 5} is proposed.

Dynamics of polynucleotide transport through nanometre-scale pores

CERN Document Server

Meller, A

2003-01-01

The transport of biopolymers through large membrane channels is a ubiquitous process in biology. It is central to processes such as gene transfer by transduction and RNA transport through nuclear pore complexes. The transport of polymers through nanoscopic channels is also of interest to physicists and chemists studying the effects of steric, hydrodynamic, and electrostatic interactions between polymers and confining walls. Single-channel ion current measurements have been recently used to study the transport of biopolymers, and in particular single-stranded DNA and RNA molecules, through nanometre-size channels. Under the influence of an electric field, the negatively charged polynucleotides can be captured and drawn through the channel in a process termed 'translocation'. During translocation, the ion current flowing through the channel is mostly blocked, indicating the presence of the polymer inside the channel. The current blockades were found to be sensitive to the properties of the biopolymers such as t...

Process R&D for Particle Size Control of Molybdenum Oxide

Energy Technology Data Exchange (ETDEWEB)

Sen, Sujat [Argonne National Lab. (ANL), Argonne, IL (United States); Dzwiniel, Trevor [Argonne National Lab. (ANL), Argonne, IL (United States); Pupek, Krzysztof [Argonne National Lab. (ANL), Argonne, IL (United States); Krumdick, Gregory [Argonne National Lab. (ANL), Argonne, IL (United States); Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-12-01

The primary goal of this study was to produce MoO<sub>3sub> powder with a particle size range of 50 to 200 μm for use in targets for production of the medical isotope ⁹⁹Mo. Molybdenum metal powder is commercially produced by thermal reduction of oxides in a hydrogen atmosphere. The most common source material is MoO<sub>3sub>, which is derived by the thermal decomposition of ammonium heptamolybdate (AHM). However, the particle size of the currently produced MoO<sub>3sub> is too small, resulting in Mo powder that is too fine to properly sinter and press into the desired target. In this study, effects of heating rate, heating temperature, gas type, gas flow rate, and isothermal heating were investigated for the decomposition of AHM. The main conclusions were as follows: lower heating rate (2-10°C/min) minimizes breakdown of aggregates, recrystallized samples with millimeter-sized aggregates are resistant to various heat treatments, extended isothermal heating at >600°C leads to significant sintering, and inert gas and high gas flow rate (up to 2000 ml/min) did not significantly affect particle size distribution or composition. In addition, attempts to recover AHM from an aqueous solution by several methods (spray drying, precipitation, and low temperature crystallization) failed to achieve the desired particle size range of 50 to 200 μm. Further studies are planned.

Integration of gas phase condensed nanoparticles in YBa{sub 2}Cu{sub 3}O{sub 7-δ} multilayers; Integration von gasphasenkondensierten Nanopartikeln in YBa{sub 2}Cu{sub 3}O{sub 7-δ}-Multilagen

Energy Technology Data Exchange (ETDEWEB)

Sparing, Maria

2012-07-01

The control and targeted variation of nanoparticles properties is a central challenge in research on particle induced defects in YBa{sub 2}Cu{sub 3}O{sub 7-δ}. Using a combined Sputter-PLD system with inert gas condensation particle size and density integrated into the YBCO multilayers were varied independently. The cooling process influences the electrical properties of the multilayers. The effect of HfO2 and FePt nanoparticles on the structural and electrical properties was studied.

Ultrafast Relaxation Dynamics of the Optical Nonlinearity in Nanometric Gold Particles

International Nuclear Information System (INIS)

Puech, K.; Blau, W.J.

2001-01-01

Measurements of the resonantly enhanced, third-order nonlinear optical properties of gold nanostructures exhibiting reduced charge-carrier mobility in three dimensions were performed with a number of ultrafast nonlinear optical techniques. The size of the particles investigated was varied between 5 and 40 nm. The magnitude of the nonlinear susceptibility is of the order of 5.10 -16 m 2 V -2 at resonance and an order of magnitude lower off-resonance. The response time of the nonlinearity is found to be extremely fast and could not be resolved in the experiments undertaken here. The only statement that can be made in this regard is that the phase relaxation time is of the order of or less than 20 fs while the energy relaxation time is of the order of or less than 75 fs

Effect of MWCNT on prepared cathode material (Li{sub 2}Mn{sub (x)}Fe{sub (1-x)}SiO{sub 4}) for energy storage applications

Energy Technology Data Exchange (ETDEWEB)

Agnihotri, Shruti, E-mail: cecm.appsc.sa@gmail.com; Rattan, Sangeeta; Sharma, A. L., E-mail: alsharmaiitkgp@gmail.com [Centre for Physical Sciences, Central University of Punjab, Bathinda-151001 (India)

2016-05-06

The electrode material Li{sub 2}MnFeSiO{sub 4} was successfully synthesized by standard sol–gel method and further modified with multiwalled carbon nano tube (MWCNT) to achieve better electrochemical properties. Our strategy helps us to improve the performance and storage capacity as compared with the bared material. This novel composite structure constructs an efficient cation (Li{sup +}) and electron channel which significantly enhance the Li{sup +} ion diffusion coefficient and reduced charge transfer resistance. Hence leads to high conductivity and specific capacity. Characterization technique like Field emission scanning electron microscopy (FESEM) has been used to confirm its morphology, structure and particle size which comes out to be of the order of ∼20 to 30 nm. Lesser particle size reveals better electrochemical properties. Electrical conductivity (∼10{sup −5} Scm{sup −1}) of MWCNT doped oxide cathode materials was recorded using ac impedance spectroscopy technique which reflects tenfold increment when compared with pure oxide cathode materials. Cyclic voltametery analysis has been done to calculate specific capacity and potential window of materials with and without CNTs. The results obtained from different techniques are well correlated and suitable for energy storage applications.

Size dependent electrical and magnetic properties of ZnFe{sub 2}O{sub 4} nanoparticles synthesized by the combustion method: Comparison between aspartic acid and glycine as fuels

Energy Technology Data Exchange (ETDEWEB)

Shanmugavani, A. [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Kalai Selvan, R., E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Layek, Samar [Department of Physics, Indian institute of Technology, Kanpur 208016 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi- 630 004, Tamil Nadu (India)

2014-03-15

Using two different fuels such as aspartic acid and glycine, the spinel zinc ferrite nanoparticles were synthesized by the combustion method at different pH values. The thermochemical calculations for both the fuel assisted materials and its adiabatic flame temperature were calculated. The X-ray diffraction (XRD) pattern revealed the formation of single phase ZnFe{sub 2}O{sub 4} with high crystallinity. The characteristic functional groups of Fe3O and Zn3O were identified through FTIR analysis. Uniform size distribution of spherical particle in the average size range of 35–100 nm was inferred from SEM images. The room temperature DC conductivities of ZnFe{sub 2}O{sub 4} particles prepared by using aspartic and glycine are in the order of 10{sup −7} and 10{sup −8} respectively. The dielectric spectral analysis inferred that the obtained dielectric constant is high at low frequency and decreases with increase in frequency. This dielectric behavior is in accordance with the Maxwell–Wagner interfacial polarization. VSM and Mössbauer analysis revealed that the prepared material exhibits paramagnetic behavior and Fe{sup 3+} state of iron content in ZnFe{sub 2}O{sub 4} at room temperature. - Highlights: • For the first time aspartic acid is used as a fuel to synthesize ZnFe{sub 2}O{sub 4} nanoparticles. • Theoretical adiabatic flame temperature for the formation of ZnFe{sub 2}O{sub 4} is calculated. • Individual spherical shape particles are achieved by combustion synthesis. • Enhanced room temperature conductivity for aspartic acid assisted particles are revealed. • Size dependent electrical and magnetic properties are demonstrated.

Structural, dielectric and gas sensing behavior of Mn substituted spinel MFe{sub 2}O{sub 4} (M=Zn, Cu, Ni, and Co) ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India); Siva Prasada Reddy, P.; Sarala Devi, G. [Inorganic and Physical Chemistry Division, Indian Institute Chemical Technology, Hyderabad 500607 (India); Sathiyaraj, S. [Department of Chemistry, Dr. NGP Institute of Technology, Coimbatore 641048, Tamil Nadu (India)

2016-01-15

Spinel ferrite (MnZnFe{sub 2}O{sub 4}, MnCuFe{sub 2}O{sub 4}, MnNiFe{sub 2}O{sub 4} and MnCoFe{sub 2}O{sub 4}) nanoparticles have been prepared by evaporation method. The annealing temperature plays an important role on changing particle size of the spinel ferrite nanoparticles was found out by X-ray diffraction and transmission electron microscopy. The role of manganese substitution in the spinel ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also creates a vital change in dielectric properties have been measured in the frequency range of 100 kHz to 5 MHz. These spinel ferrites are decomposed to α-Fe{sub 2}O{sub 3} after annealing above 550 °C in air. Through the characterization of the prepared powder, the effect of annealing temperature, chemical composition and preparation technique on the microstructure, particle size and dielectric properties of the Mn substituted spinel ferrite nanoparticles are discussed. Furthermore, Conductance response of Mn substituted MFe{sub 2}O{sub 4} ferrite nanoparticles were measured by exposing the materials to reducing gas like liquefied petroleum gas (LPG). - Highlights: • The egg white support to achieve sample with shorter reaction time. • Manganese plays a significant role in sensor response. • Nature of the ferrites was affected with increasing annealing temperature.

Synthesis and characterization of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} nanoparticle ferrofluids for thermo-electric conversion

Energy Technology Data Exchange (ETDEWEB)

Sansom, C.L., E-mail: c.l.sansom@cranfield.ac.uk [Cranfield University, Cranfield MK43 0AL (United Kingdom); Jones, P.; Dorey, R.A.; Beck, C.; Stanhope-Bosumpim, A. [Cranfield University, Cranfield MK43 0AL (United Kingdom); Peterson, J. [Peterson Dynamics Ltd., 9 Nant y Gamar Road, Craig y Don LL30 1YE (United Kingdom)

2013-06-15

Ferrofluids containing nanoparticles of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} (MZ5) and Fe{sub 3}O{sub 4} (magnetite) have been examined as potential thermal transport media and energy harvesting materials. The ferrofluids were synthesized by chemical co-precipitation and characterized by EDX to determine composition and by TEM to determine particle size and agglomeration. A range of particle coatings and carrier fluids were used to complete the fluid preparation. Commercially available ferrofluids were tested in custom built rigs to demonstrate both thermal pumping (for waste heat removal applications) and power induction (for power conversion and energy harvesting applications). The results indicate that simple ferrofluids possess the necessary properties to remove waste heat, either into thermal storage or for conversion to electrical power. - Highlights: ► The synthesis of nanoparticle ferrofluids based on Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} is reported. ► The thermal properties of the ferrofluids creates a novel pump with no moving parts. ► Thermal energy harvesting for conversion into electrical power is demonstrated.

Particle and NO{sub x} Emissions from a HVO-Fueled Diesel Engine

Energy Technology Data Exchange (ETDEWEB)

Happonen, M.

2012-10-15

Concerns about oil price, the strengthening climate change and traffic related health effects are all reasons which have promoted the research of renewable fuels. One renewable fuel candidate is diesel consisting of hydrotreated vegetable oils (HVO). The fuel is essentially paraffinic, has high cetane number (>80) and contains practically no oxygen, aromatics or sulphur. Furthermore, HVO fuel can be produced from various feedstocks including palm, soybean and rapeseed oils as well as animal fats. HVO has also been observed to reduce all regulated engine exhaust emissions compared to conventional diesel fuel. In this thesis, the effect of HVO fuel on engine exhaust emissions has been studied further. The thesis is roughly divided into two parts. The first part explores the emission reductions associated with the fuel and studies techniques which could be applied to achieve further emission reductions. One of the studied techniques was adjusting engine settings to better suit HVO fuel. The settings chosen for adjustments were injection pressure, injection timing, the amount of EGR and the timing of inlet valve closing (with constant inlet air mass flow, i.e. Miller timing). The engine adjustments were also successfully targeted to reduce either NO{sub x} or particulate emissions or both. The other applied emission reduction technique was the addition of oxygenate to HVO fuel. The chosen oxygenate was di-n-pentyl ether (DNPE), and tested fuel blend included 20 wt-% DNPE and 80 wt-% HVO. Thus, the oxygen content of the resulting blend was 2 wt-%. Reductions of over 25 % were observed in particulate emissions with the blend compared to pure HVO while NOx emissions altered under 5 %. On the second part of this thesis, the effect of the studied fuels on chosen surface properties of exhaust particles were studied using tandem differential mobility analyzer (TDMA) techniques and transmission electron microscopy (TEM). The studied surface properties were oxidizability and

Investigation of Al{sub 2}O{sub 3} barrier film properties made by atomic layer deposition onto fluorescent tris-(8-hydroxyquinoline) aluminium molecular films

Energy Technology Data Exchange (ETDEWEB)

Maindron, Tony; Aventurier, Bernard [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Ghazouani, Ahlem; Jullien, Tony [LETI/DTSI/SDEP/Laboratoire Dépôt Equipe 2, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Rochat, Névine [LETI/DTSI/Service de Caractérisation des Matériaux et Composants, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Simon, Jean-Yves; Viasnoff, Emilie [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

2013-12-02

Al{sub 2}O{sub 3} films have been deposited at 85 °C by atomic layer deposition onto single 100 nm thick tris-(8-hydroxyquinoline) aluminium (AlQ{sub 3}) films made onto silicon wafers. It has been found that a thick ALD-deposited Al{sub 2}O{sub 3} layer (> 11 nm) greatly prevents the photo-oxidation of AlQ{sub 3} films when exposed to continuous UV irradiation (350 mW/cm{sup 2}). Thin Al{sub 2}O{sub 3} thicknesses (< 11 nm) on the contrary yield lower barrier performances. Defects in the Al{sub 2}O{sub 3} layer have been easily observed as non-fluorescent AlQ{sub 3} singularities, or black spots, under UV light on the system Si/AlQ{sub 3}/Al{sub 2}O{sub 3} stored into laboratory conditions (22 °C/50% Relative Humidity (RH)) for long time scale (∼ 2000 h). Accelerated aging conditions in a climatic chamber (85 °C/85% RH) also allow faster visualization of the same defects (168 h). The black spot density grows upon time and the black spot density occurrence rates have been calculated to be 0.024 h{sup −1}·cm{sup −2} and 0.243 h{sup −1}·cm{sup −2} respectively for the two testing conditions. A detailed investigation of these defects did show that they cannot be ascribed to the presence of a detectable particle. In that sense they are presumably the consequence of the existence of nanometre-scaled defects which cannot be detected onto fresh samples. Interestingly, an additional overcoating of ebeam-deposited SiO{sub 2} onto the Si/AlQ{sub 3}/Al{sub 2}O{sub 3} sample helps to decrease drastically the black spot density occurrence rates down to 0.004 h{sup −1}·cm{sup −2} and 0.04 h{sup −1}·cm{sup −2} respectively for 22 °C/50% RH and 85 °C/85% RH testing conditions. These observations highlight the moisture sensitivity of low temperature ALD-deposited Al{sub 2}O{sub 3} films and confirm the general idea that a single Al{sub 2}O{sub 3} ALD film performs as an ultra-high barrier but needs to be overprotected from water condensation by an

Contact mechanics at nanometric scale using nanoindentation technique for brittle and ductile materials.

Science.gov (United States)

Roa, J J; Rayon, E; Morales, M; Segarra, M

2012-06-01

In the last years, Nanoindentation or Instrumented Indentation Technique has become a powerful tool to study the mechanical properties at micro/nanometric scale (commonly known as hardness, elastic modulus and the stress-strain curve). In this review, the different contact mechanisms (elastic and elasto-plastic) are discussed, the recent patents for each mechanism (elastic and elasto-plastic) are summarized in detail, and the basic equations employed to know the mechanical behaviour for brittle and ductile materials are described.

Sintering effect on structural, magnetic and optical properties of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ferrite nano particles

Energy Technology Data Exchange (ETDEWEB)

Kannan, Y.B., E-mail: ybkans@gmail.com [Department of Physics, Arumugam Pillai Seethai Ammal College, Tiruppattur 630211 (India); Saravanan, R. [PG & Research Department of Physics, The Madura College, Madurai 625011 (India); Srinivasan, N. [PG & Research Department of Physics, Thiagarajar College, Madurai 625009 (India); Ismail, I. [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

2017-02-01

Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano ferrite particles have been prepared by mechanical alloying via high energy ball milling and sintered at different temperatures from 700 °C to 1000 °C. Spinel structure is confirmed from the analysis of XRD data. Rietveld refinement method is employed to refine the XRD powder data and the structural parameters are calculated from the refinement. Small amount of hematite phase is found in all samples. The SEM, EDAX and XRF analysis reveals respectively the morphology, stoichiometric composition and purity of the powder samples. Using Maximum Entropy Method (MEM) the values of the bond strength between various sites interactions in ferrites are evaluated and compared with theoretical predictions of strengthening/weakening of various sites interactions from the values of interionic distances and interionic bond angles. Ferromagnetic nature of the samples is confirmed from the vibrating sample magnetometer study. The obtained low saturation magnetization values are attributed to presence of second phase. The optical band gap energy of the samples was determined by using UV–VIS techniques. - Highlights: • Raw XRD data were refined using Rietveld refinement method using JANA 2006 software. • Fraction of zinc ions occupies at B site. • Bond strength between the atoms at A-site and B-site is studied by employing maximum entropy method (MEM). • From the MEM result, numerical values of the bond strength between various interactions (A–B, A–A, B–B) have been evaluated. • Various sites interactions results are compared with that of hitherto existing theoretical predictions.

Synthesis of basalt fiber@Zn{sub 1-x}Mg{sub x}O core/shell nanostructures for selective photoreduction of CO{sub 2} to CO

Energy Technology Data Exchange (ETDEWEB)

Kwak, Byeong Sub; Kim, Kang Min [Department of Chemistry, College of Science, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of); Park, Sun-Min, E-mail: psm@kicet.re.kr [Korea Institute of Ceramic Engineering and Technology (KICET), Jinju, Gyeongnam 52851 (Korea, Republic of); Kang, Misook, E-mail: mskang@ynu.ac.kr [Department of Chemistry, College of Science, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of)

2017-06-15

Highlights: • ZnO and Zn{sub 1-x}Mg{sub x}O crystals were grown onto the BFs. • The core@shell structured BF@Zn{sub 1-x}Mg{sub x}O particles significantly increased the adsorption of CO{sub 2} gas. • The BF@ZnO or BF@Zn{sub 1-x}Mg{sub x}O particles selectively reduce the carbon dioxide to carbon monoxide. - Abstract: This study focused on the development of a catalyst for converting carbon dioxide, the main cause of global warming, into a beneficial energy source. Core@shell structured particles, BF@ZnO and BF@Zn{sub 1-x}Mg{sub x}O, are synthesized in order to selectively obtain CO gas from the photoreduction of CO{sub 2}. A modified sol-gel process is used to synthesize the core@shell structures with a three-dimensional microstructure, which are subsequently characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDAX), ultraviolet (UV)–vis absorption, photoluminescence (PL), and photocurrent density analysis. The CO{sub 2} adsorption abilities of the core@shell particles are estimated through CO{sub 2}-temperature programmed desorption (TPD). The core@shell structured BF@Zn{sub 1-x}Mg{sub x}O particles including the Mg ingredient significantly increased the adsorption of CO{sub 2} gas at the microfiber/nanoparticle interface. Both the BF@ZnO and BF@Zn{sub 1-x}Mg{sub x}O particles selectively reduce the carbon dioxide to carbon monoxide, with almost no other reduced products being observed. These results are attributed to the effective adsorption of CO{sub 2} gas and inhibited recombination of the photogenerated electron–hole pairs. BF@Zn{sub 0.75}Mg{sub 0.25}O exhibited superior photocatalytic behavior and selectively produced 5.0 μmolg{sub cat}{sup −1} L{sup −1} of CO gas after 8 h of reaction.

Preparation of ultrafine iron particles by chemical vapor deposition of Fe(CO) sub 5. Fe(CO) sub 5 wo gebryo to suru kiso kagaku hanno ni yoru tetsuchobiryushi no seisei

Energy Technology Data Exchange (ETDEWEB)

Sawada, Y; Kageyama, Y. (Mitsubishi Petrochemical Co. Ltd., Tokyo (Japan)): Iwata, M. (Nagoya University, Nagoya (Japan). Faculty of Engineering)

1991-11-10

An ultrafine iron particle preparing process was developed, which wses gaseous phase pyrolysis in magnetic field of iron pentacarbonyl, Fe(CO){sub 5}, based on the fact that Fe(CO){sub 5} has peculiar characters that its boiling point is as low as 103{degree}C, and starts decomposing in a low temperature zone of 100{degree}C or lower. Vaporizing and introducing into a reactor an fe(CO){sub 5}, andPyrolyzing it at 200-600{degree}C while being diluted with nitrogen and applied with a magnetic field produced uitrafine iron particles of a necklace-like chain comprisinh primary particles having diameter of 15 to 25 nm with 10 to 40 of them linked in a straight chain. It was found that the specific surface area is 30-50 m{sup 2}/g, with the diameter converted from the specific surface area being relatively close to the average diameter obtained from TEM photograph, and that the particle has few pores. Magnetically the iron powder has a coercivity of 123-131 KA/m and a specific saturation magnetization of 120-140 Am{sup 2}/kg, and is expected to be applied as a high density magnetic recording medium. 5 refs.,8 figs., 3 tabs.

Heterogeneous photo-Fenton degradation of acid red B over Fe{sub 2}O{sub 3} supported on activated carbon fiber

Energy Technology Data Exchange (ETDEWEB)

Lan, Huachun [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,China (China); Wang, Aiming [Department of Municipal and Environmental Engineering, School of Civil Engineering, Beijing Jiaotong University,China (China); Liu, Ruiping, E-mail: liuruiping@rcees.ac.cn [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,China (China); Liu, Huijuan; Qu, Jiuhui [Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,China (China)

2015-03-21

Highlights: • Fe{sub 2}O{sub 3} with small particle size was highly dispersed on activated carbon fiber. • Fe{sub 2}O{sub 3}/ACF exhibited higher photo-Fenton activity toward ARB degradation. • Fe{sub 2}O{sub 3}/ACF has an excellent long-term stability without obvious deactivation. - Abstract: Fe{sub 2}O{sub 3} supported on activated carbon fiber (Fe{sub 2}O{sub 3}/ACF) was prepared via an impregnation method and characterized by X-ray diffraction, scanning electron microscopy and BET analysis. The results indicated that Fe{sub 2}O{sub 3} with small particle size was highly dispersed on the surface of the ACF and the introduction of Fe{sub 2}O{sub 3} did not change the ACF pore structure. Fe{sub 2}O{sub 3}/ACF exhibited a higher Fenton efficiency for the degradation of acid red B (ARB), especially under simulated solar irradiation. Complete decoloration of the ARB solution and 43% removal of TOC could be achieved within 200 min under optimal conditions. It was verified that more ·OH radicals were generated in the photo-assisted Fenton process and involved as active species in ARB degradation. FTIR analysis indicated that the degradation of ARB was initiated through the cleavage of −N=N−, followed by hydroxylation and opening of phenyl rings to form aliphatic acids, and further oxidation of aliphatic acids would produce CO{sub 2} and H{sub 2}O. Moreover, Fe{sub 2}O{sub 3}/ACF maintained its activity after being reused 4 times and the release of iron from the catalyst was found to be insignificant during the Fenton and photo-Fenton processes, indicating that Fe{sub 2}O{sub 3}/ACF had good long-term stability.

Investigation of nano-SiC{sub p} effect on microstructure and mechanical properties of Al/TiH{sub 2} foam precursor produced via ARB process

Energy Technology Data Exchange (ETDEWEB)

Hosseini, S.M., E-mail: sm.hosseini@ma.iut.ac.ir; Habibolahzadeh, A.

2015-07-15

In this study, a new type of hybrid composite which can be potentially used as a foam precursor was achieved by 0.75 TiH{sub 2} and 0.75 nano-SiC{sub p} addition (wt%) between 5 pure Al strips, followed by 6 accumulative roll bonding (ARB) cycles at room temperature. The effect of nano-SiC particles addition on the resulting microstructures as well as the corresponding mechanical properties of the products was investigated. Al/0.75 wt% TiH{sub 2} sheets were also fabricated by the ARB process to compare with the hybrid nanocomposite specimens. Scanning electron microscopy (SEM) and related EDS color images revealed that applying 6 ARB cycles led to fairly homogeneous distribution of the TiH{sub 2} and nano-SiC{sub p} and elimination of porosity between the particles and matrix. It was also found that the tensile strength of the Al/TiH{sub 2}/nano-SiC hybrid composite was about 1.27 times higher than that of the Al/TiH{sub 2} precursor. SEM observation of fractured surfaces showed that the failure mechanism of the composite and nanocomposite was shear ductile rupture.

Composition and sources of particles in Mannerheimintie during exceedance days of PM{sub 10} limit value in 2009; Hiukkasten koostumus ja laehteet Mannerheimintiellae PM{sub 10}-raja-arvon ylityspaeivinae 2009

Energy Technology Data Exchange (ETDEWEB)

Kupiainen, K.; Stojiljkovic, A.; Ritola, R. (Nordic Envicon Oy, Helsinki (Finland))

2011-06-15

The purpose of the work was to determine sources of thoracic particles (PM{sub 10}) in the center of Helsinki, in Mannerheimintie, in 2009 during the days when the daily average concentration of PM{sub 10} exceeded 50 mug/m3. Work was commissioned by the Helsinki City Public Works department, the Helsinki Environment Centre and the Helsinki Region Environmental Services Authority HSY (formerly YTV). By the end of the year there were altogether 30 exceedance days. The allowed number of exceedance days per year is 35, so the limit value was not exceeded in 2009. HSY is responsible for monitoring the air quality in the Helsinki metropolitan area. The PM{sub 10} monitoring data in combination with electron microscopy based single particle compositional analysis and receptor modeling was used to evaluate dust source contributions on the exceedance days at HSY's air quality monitoring station in Mannerheimintie. Dust sources related to traction control (winter maintenance and pavement wear by studded tyres) contributed most to the PM{sub 10} concentrations in Mannerheimintie. On 12 exceeding days this group accounted for more than 50 % of PM{sub 10} particles, on 3 days the group alone was sufficient to cause the exceedance. On 3 of the exceedance days long-range transboundary air pollution or traffic exhaust emissions were on the same level with the traction control sources. On 11 days the most significant impact came from construction sites. (orig.)

Performance comparison of scintillators for alpha particle detectors

Energy Technology Data Exchange (ETDEWEB)

Morishita, Yuki [Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi 461-8673 (Japan); Japan Atomic Energy Agency, Muramatsu 4-33, Tokai-mura, Ibaraki 319-1194 (Japan); Yamamoto, Seiichi [Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi 461-8673 (Japan); Izaki, Kenji [Japan Atomic Energy Agency, Muramatsu 4-33, Tokai-mura, Ibaraki 319-1194 (Japan); Kaneko, Junichi H.; Toui, Kohei; Tsubota, Youichi; Higuchi, Mikio [Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)

2014-11-11

Scintillation detectors for alpha particles are often used in nuclear fuel facilities. Alpha particle detectors have also become important in the research field of radionuclide therapy using alpha emitters. ZnS(Ag) is the most often used scintillator for alpha particle detectors because its light output is high. However, the energy resolution of ZnS(Ag)-based scintillation detectors is poor because they are not transparent. A new ceramic sample, namely the cerium doped Gd{sub 2}Si{sub 2}O{sub 7} (GPS) scintillator, has been tested as alpha particle detector and its performances have been compared to that one of three different scintillating materials: ZnS(Ag), GAGG and a standard plastic scintillator. The different scintillating materials have been coupled to two different photodetectors, namely a photomultiplier tube (PMT) and a Silicon Photo-multiplier (Si-PM): the performances of each detection system have been compared. Promising results as far as the energy resolution performances (10% with PMT and 14% with Si-PM) have been obtained in the case of GPS and GAGG samples. Considering the quantum efficiencies of the photodetectors under test and their relation to the emission wavelength of the different scintillators, the best results were achieved coupling the GPS with the PMT and the GAGG with the Si-PM.

Solid-state synthesis of Li{sub 4}Ti{sub 5}O{sub 12} for high power lithium ion battery applications

Energy Technology Data Exchange (ETDEWEB)

Han, Seung-Woo [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ryu, Ji Heon [Graduate School of Knowledge-Based Technology and Energy, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Jeong, Joayoung [Cell Precedence Development Group, Samsung SDI, Yongin 446-577 (Korea, Republic of); Yoon, Dang-Hyok, E-mail: dhyoon@ynu.ac.kr [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of)

2013-09-05

Highlights: •High energy milling using 0.30 and 0.45 mm beads for Li{sub 4}Ti{sub 5}O{sub 12} synthesis. •Synthesis of 162 nm-sized pure Li{sub 4}Ti{sub 5}O{sub 12} by solid-state reaction. •Spray drying using fine starting materials to confer paste tackiness. •High capacity of 174 mAh/g and adequate rate properties for high power LIBs applications. -- Abstract: Li{sub 4}Ti{sub 5}O{sub 12} was synthesized by a solid-state reaction between Li{sub 2}CO{sub 3} and anatase TiO{sub 2} for applications to high power lithium ion batteries. The starting materials underwent 6 h of high energy milling using ZrO{sub 2} beads with two different sizes, 0.30 and 0.45 mm. The smaller ZrO{sub 2} beads resulted in finer starting materials. Spray drying was also performed on the 0.30 mm beads-treated particles to enhance the screen printability of a paste containing this powder. The finer starting materials showed a pure 162 nm-sized Li{sub 4}Ti{sub 5}O{sub 12} due to the decreased diffusion length for a solid-state reaction, whereas the 0.45 mm beads-treated starting materials resulted in a 242 nm-sized Li{sub 4}Ti{sub 5}O{sub 12} phase containing 2 wt.% of rutile TiO{sub 2} that had transformed from the anatase phase during heat treatment at 800 °C for 3 h. The finer Li{sub 4}Ti{sub 5}O{sub 12} showed higher charge capacity and better charge/discharge rates than the coarser particles, which highlights the importance of the primary particle size on the electrochemical properties of Li{sub 4}Ti{sub 5}O{sub 12} for high power applications. The fine Li{sub 4}Ti{sub 5}O{sub 12} particles had a discharge capacity of 174 mAh/g at 0.1 C and capacity retention of 80% at 10.0 C.

Studies on femtosecond fluorescence dynamics of photosystem II Particle complex at low temperature

CERN Document Server

Liu Xiao; He, Jun Fang; Cai, Xia; Peng Jun Fang; Kuang Ting Yun

2004-01-01

In order to understanding the diversity of energy transfer in PS II at different temperatures, PS II particle complex purified from spinach was investigated with femtosecond time-resolved fluorescence spectroscopy in the case of excitation 507 nm at 83 K, 160 K, 273 K. The data were analyzed by Gauss analysis and fluorescence decay time- fitting. Some results were achieved. (1) Increase of the temperature results in a broadening of the fluorescence emission spectra due to the temperature-dependent expressions for nonradiative transitions between two electronic states. (2) There are at least several characteristic Chl molecules exist in PS II particle complex, i.e. Chl b/sub 639//sup 640/, Chl b/sub 640//sup 645/, Chl a/sub 660//sup 663/, Chl a/sub 667//sup 668/, Chl a/sub 673//sup 676/, Chl a/sub 680 //sup 681/, Chl a/sub 680/681//sup 682/, Chl a/sub 684,685//sup 668 /689/, Chl a/sub 688//sup 698/, (Chl a/b/sub a//sup e/: a represents the peak of absorption, e represents the peak of emission). (3) Though the ...

Formation of the ZnFe{sub 2}O{sub 4} phase in an electric arc furnace off-gas treatment system

Energy Technology Data Exchange (ETDEWEB)

Suetens, T., E-mail: thomas.suetens@mtm.kuleuven.be; Guo, M., E-mail: muxing.guo@mtm.kuleuven.be; Van Acker, K., E-mail: karel.vanacker@lrd.kuleuven.be; Blanpain, B., E-mail: bart.blanpain@mtm.kuleuven.be

2015-04-28

Highlights: • EAF dust was characterized with particle size analysis, XRF, and EPMA. • Slag particles showed no sign of reaction with Zn vapor. • Fe{sub 2}O{sub 3} particles showed different degrees of reaction based on their size. • The thermodynamic stability of Zn vapor in EAF off-gas ducts was reevaluated. • In presence of Fe{sub 2}O{sub 3}, Zn vapor reacts to form ZnFe{sub 2}O{sub 4} and ZnO. - Abstract: To better understand the phenomena of ZnFe{sub 2}O{sub 4} spinel formation in electric arc furnace dust, the dust was characterized with particle size analysis, X-ray fluorescence (XRF), electron backscatter diffraction (EBSD), and electron probe micro-analysis (EPMA). Different ZnFe{sub 2}O{sub 4} formation reaction extents were observed for iron oxide particles with different particle sizes. ZnO particles were present as both individual particles and aggregated on the surface of larger particles. Also, the slag particles found in the off-gas were shown not to react with the zinc vapor. After confirming the presence of a ZnFe{sub 2}O{sub 4} formation reaction, the thermodynamic feasibility of in-process separation – a new electric arc furnace dust treatment technology – was reevaluated. The large air intake and the presence of iron oxide particles in the off-gas were included into the thermodynamic calculations. The formation of the stable ZnFe{sub 2}O{sub 4} spinel phase was shown to be thermodynamically favorable in current electric arc furnace off-gas ducts conditions even before reaching the post combustion chamber.

Electrochemical activity of Li{sub 2}FeTiO{sub 4} and Li{sub 2}MnTiO{sub 4} as potential active materials for Li ion batteries: A comparison with Li{sub 2}NiTiO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Kuezma, Mirjana; Dominko, Robert; Bele, Marjan; Jamnik, Janko [National Institute of Chemistry, Ljubljana (Slovenia); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana (Slovenia); Makovec, Darko [Jozef Stefan Institute, Ljubljana (Slovenia); Gaberscek, Miran [National Institute of Chemistry, Ljubljana (Slovenia); Faculty of Chemistry and Chemical Technology, University of Ljubljana (Slovenia)

2009-04-01

We demonstrate, for the first time, a considerable electrochemical activity of two members of lithium transition element titanates: Li{sub 2}FeTiO{sub 4} and Li{sub 2}MnTiO{sub 4}. Both materials consist of 10-20 nm particles embedded in a conductive carbon coating. We show that not the coating but the small particle size is decisive for materials' activity. Li{sub 2}FeTiO{sub 4} shows a stable reversible capacity of up to 123 mA hg{sup -1} at C/20 and 60 C which is 83% of the theoretical value for exchange of 1 electron (148 mA hg{sup -1}). Li{sub 2}MnTiO{sub 4} could only be prepared in a nanosized form that contained about 30% of impurities. The capacity of the whole material (including impurities) is comparable to that of Li{sub 2}FeTiO{sub 4} but the cycling stability is much poorer. In contrast to the Fe and Mn analogues, the third member of the titanate family, Li{sub 2}NiTiO{sub 4}, shows a good electrochemistry even when the particle size is much larger (about 100 nm). During initial cycles at C/10 and 60 C, exchange of more than 1 electron per compound formula has been observed. The cycling stability at high temperatures, however, is poor. (author)

Effects of aging on PuO{sub 2} . xH{sub 2}O particle size in alkaline solution

Energy Technology Data Exchange (ETDEWEB)

Delegard, C.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

2013-08-01

Between 1944 and 1989, 54.5 metric tons of the United States' weapons-grade plutonium and an additional 12.9 metric tons of fuels-grade plutonium were produced in and separated from irradiated uranium metal fuel at the Hanford Site. Acidic high-activity wastes containing around 600 kg of plutonium were made alkaline and discharged to underground storage tanks from separations, isolation, and recycle processes to yield average plutonium concentration of about 0.003 g/L (or {proportional_to} 0.0002 wt. %) in the {proportional_to} 200 million liter tank waste volume. The plutonium is largely associated with low-solubility metal hydroxide/oxide sludges where its low concentration and intimate mixture with neutron-absorbing elements (e.g., iron) are credited in nuclear criticality safety. However, concerns have been expressed that plutonium, in the form of hydrated plutonium oxide, PuO{sub 2} . xH{sub 2}O, could undergo sufficient crystal growth through dissolution and reprecipitation in the alkaline tank waste to potentially become separable from neutron absorbing constituents by settling or sedimentation. Thermodynamic considerations and laboratory studies of systems chemically analogous to tank waste show that the plutonium, precipitated in the alkaline tank waste by neutralization from acid solution, probably entered as 2-5-nm PuO{sub 2} . xH{sub 2}O, crystallite particles that, because of the low concentration of the neutral Pu(IV) dissolved species and opposition from radiolytic processes, grow from that point at exceedingly slow rates. (orig.)

Seasonal variation of aliphatic amines in marine sub-micrometer particles at the Cape Verde islands

Directory of Open Access Journals (Sweden)

H. Herrmann

2009-12-01

Full Text Available Monomethylamine (MA, dimethylamine (DMA and diethylamine (DEA were detected at non-negligible concentrations in sub-micrometer particles at the Cap Verde Atmospheric Observatory (CVAO located on the island of São Vicente in Cape Verde during algal blooms in 2007. The concentrations of these amines in five stage impactor samples ranged from 0–30 pg m⁻³ for MA, 130–360 pg m⁻³ for DMA and 5–110 pg m⁻³ for DEA during the spring bloom in May 2007 and 2–520 pg m⁻³ for MA, 100–1400 pg m⁻³ for DMA and 90–760 pg m⁻³ for DEA during an unexpected winter algal bloom in December 2007. Anomalously high Saharan dust deposition and intensive ocean layer deepening were found at the Atmospheric Observatory and the associated Ocean Observatory during algal bloom periods. The highest amine concentrations in fine particles (impactor stage 2, 0.14–0.42 μm indicate that amines are likely taken up from the gas phase into the acidic sub-micrometer particles. The contribution of amines to the organic carbon (OC content ranged from 0.2–2.5% C in the winter months, indicating the importance of this class of compounds to the carbon cycle in the marine environment. Furthermore, aliphatic amines originating from marine biological sources likely contribute significantly to the nitrogen content in the marine atmosphere. The average contribution of the amines to the detected nitrogen species in sub-micrometer particles can be non-negligible, especially in the winter months (0.1% N–1.5% N in the sum of nitrate, ammonium and amines. This indicates that these smaller aliphatic amines can be important for the carbon and the nitrogen cycles in the remote marine environment.

Tribomechanical behavior of B{sub 4}C{sub p} reinforced Al 359 composites

Energy Technology Data Exchange (ETDEWEB)

Ramasamy, Deivasigamani; Rathanasamy, Rajasekar [Kongu Engineering College, Tamil Nadu (India). Dept. of Mechanical Engineering; Subramanian, Mohan Kumar; Kaliyannan, Gobinath Velu [PAAVAI Engineering College, Tamil Nadu (India). Dept. of Mechatronics Engineering; Palaniappan, Sathish Kumar [Indian Institute of Technology, Kharagpur, West Bengal (India); Durairaj, Jayanth

2017-03-01

n the present investigation, the influence of B{sub 4}C{sub p} particles on the mechanical and tribological behavior of Al 359 composites has been studied. B{sub 4}C{sub p} particle reinforced Al 359 composite samples were prepared by stir casting process. Hardness, tensile strength and wear behavior of the composites were studied and compared with a control specimen. Hardness of B{sub 4}C{sub p} particles reinforced Al 359 matrix increases compared to base matrix due to the presence of the ceramic phase. Coefficient of friction considerably increases with up to 20 wt.-% addition of B{sub 4}C{sub p} in base matrix. Specimens were subjected to wear tests under different load conditions and the following five different wear mechanisms such as wear groove, abrasion, delamination, oxidation and plastic deformation were evaluated. The abrasion results prove the increase in wear resistance of B{sub 4}C{sub p} reinforced composites compared to a control specimen.

Hydrothermal degradation of tetragonal ZrO{sub 2} ceramic components used in dental applications; Efeito da degradacao em meio aquoso de componentes ceramicos a base de ZrO{sub 2} tetragonal para uso odontologico

Energy Technology Data Exchange (ETDEWEB)

Mukaeda, L.E.; Robin, A.; Taguchi, S.P. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Santos, C. [ProtMat Materiais Avancados, Guaratingueta, SP (Brazil)

2009-07-01

With the evolution of the dental restoration techniques, a considerable growth in the demand of ceramic products occurred. These materials present good strength associated to reliability. In this work, micrometric and nanometric scale tetragonal ZrO{sub 2} blocks were sintered at 1500 deg C-2h and 1350 deg C-2h, respectively, ground and polished. Ceramics with relative density higher than 98% were obtained. The specimens were immersed in hot water (150 deg C), for times ranging from 10h to 30h. The mass variation of the samples was measured and the crystalline phases present before and after the degradation tests were identified by X-ray diffractometry, in order to evaluate the capacity of these ceramics in resisting to aqueous medium exposure. Materials with nanometric structure present higher resistance to degradation than those with micrometric scale, and this interferes in structural stability after the test, and reduces the martensitic transformation. (author)

Features of pseudogap and superconductivity states of YBa sub 2 Cu sub 3 O sub 7 sub - sub x

CERN Document Server

Misochko, O V; Dekorsy, T; Helm, M

2002-01-01

The relaxation dynamics of the lattice and low-energy quasi-particles of the YBa sub 2 Cu sub 3 O sub 7 sub - sub x superconductor is studied through the light reflection method within the wide temperature range. It is shown that for T > T sub c there exist two areas of temperature with qualitatively and quantitatively different excitation dynamics and the transition between these areas is of the hysteresis character. It is established also, that the character of the change in the relaxation dynamics of the charge carriers in the superconducting state indicates the anisotropic gap with zeroes on the Fermi surface

Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates prepared with a coordination-complex method

Energy Technology Data Exchange (ETDEWEB)

Guo, Rui [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China); You, Junhua [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); Liu, Xuanwen, E-mail: lxw@mail.neuq.edu.cn [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China)

2017-02-28

Highlights: • The crystallization mechanism relies on Ho{sup 3+} and Cu{sup 2+} diffusion. • The Ho{sub 2}Cu{sub 2}O{sub 5} particles are refined by the coordination complex method under N{sub 2} environment. • The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon is enhanced. - Abstract: Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc){sub 2}(OAc)(H{sub 2}O){sub 3}]·8H{sub 2}O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N{sub 2} environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho{sub 2}Cu{sub 2}O{sub 5} formed through the diffusion of CuO into Ho{sub 2}O{sub 3} particles. Cu{sup 2+} diffused faster than Ho{sup 3+} during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N{sub 2} atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho{sub 2}Cu{sub 2}O{sub 5} particles. The final Ho{sub 2}Cu{sub 2}O{sub 5} particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N{sub 2} played important roles in determining the morphology of the resulting Ho{sub 2}Cu{sub 2}O{sub 5}. The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.