Elastic, electronic properties and intra-atomic bonding in orthorhombic and tetragonal polymorphs of BaZn2As2 from first-principles calculations

International Nuclear Information System (INIS)

Shein, I.R.; Ivanovskii, A.L.

2014-01-01

Highlights: • α and β polymorphs of BaZn 2 As 2 as a parent phase of the new DMSs are examined. • Structural, elastic, electronic properties are evaluated from first principles. • Inter-atomic bonding picture is discussed. -- Abstract: Very recently, on the example of hole- and spin-doped BaZn 2 As 2 , quite an unexpected area of potential applications of 122-like phases was proposed as a promising platform for searching the new diluted magnetic semiconductors (DMSs) (2013; K. Zhao, et al, Nature Commun. 4:1442). Herein, by means of the first-principles calculations, we have examined in detail the basic structural, elastic, electronic properties and the peculiarities of the inter-atomic bonding in α and β polymorphs of 122-like BaZn 2 As 2 – a parent phase of the new DMSs. Our characterization of these materials covers the optimized structural parameters, the main elastic parameters (elastic constants, bulk, shear, and Young’s moduli, Poisson’s ratio, anisotropy indexes, and Pugh’s criterion), as well as electronic bands and densities of electronic states

Desorption of organic molecules with fast incident atomic and polyatomic ions

International Nuclear Information System (INIS)

Hunt, J.E.; Salehpour, M.; Fishel, D.L.

1989-01-01

In 1974, Macfarlane and coworkers introduced a new mass spectrometric technique based on desorption-ionization of sample molecules from solid targets by the impact of fast heavy ions (fission fragments) from 252 Cf. The process of ion-induced desorption of molecular ions from surfaces is not yet fully understood, although a large amount of experimental data related to the mechanism has been published. This paper concerns the use of fast incident polyatomic ions to induce desorption of secondary molecular ions of valine and chlorophyll from surfaces. Polyatomic ions are unique in that they are a collection of temporally and spatially correlated atoms. The main finding in this study is that incident polyatomic ions produce drastic enhancements in the secondary ion yields over atomic ions. Also, two types of nonlinear effects in desorption have been observed and will be discussed

Changes of disease incidence among atomic-bomb survivors 1956-78

International Nuclear Information System (INIS)

Hamada, Tadao; Matsushita, Hiroshi.

1978-01-01

Statistical observation was made concerning changes with time of incidences of various diseases in autopsy cases since 1956 when Atomic Bomb Hospital was established, and the following results were obtained. The incidence of lung cancer tended to increase in men and women of both groups (an exposed group and a non-exposed group). A marked decrease of the incidence of leukemia was recognized in men and women of both groups, and a decrease of that of malignant lymphoma was recognized in men. The incidence of liver cirrhosis and hepatic cancer tended to decrease in men and women of both groups. The incidence of colon cancer tended to increase in both groups, but that of stomach cancer decreased recently in men and women of both groups. Incidences of digestive organ diseases, cardiovascular diseases, cerebrovascular disorder, and respiratory organ diseases tended to increase in both groups, but urinary tract diseases, infectious diseases, and blood diseases tended to decrease in both groups, which suggested an increase of older persons' diseases due to aging of the exposed. Incidences of various diseases in the exposed changed almost in parallel with those in the non-exposed, and a difference in incidences of various diseases tended to be shortened. (Tsunoda, M.)

Crystal structure and thermoelectric properties of clathrate, Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}: Small cage volume and large disorder of the guest atom

Energy Technology Data Exchange (ETDEWEB)

Roudebush, John H., E-mail: jhr@princeton.edu [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Orellana, Mike [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Bux, Sabah [Thermal Energy Conversion Technologies Group, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Yi Tanghong; Kauzlarich, Susan M. [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States)

2012-08-15

Samples with the type-I clathrate composition Ba{sub 8}Ni{sub x}Si{sub 46-x} have been synthesized and their structure and thermoelectric properties characterized. Microprobe analysis indicates the Ni incorporation to be 2.62{<=}x{<=}3.53. The x=3.5 phase crystallizes in the type-I clathrate structure (space group: Pm-3n) with a lattice parameter of 10.2813(3) A. The refined composition was Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}, with small vacancies, 0.4 and 0.5 atoms per formula unit, at the 2a and 6c sites, respectively. The position of the Ba2 atom in the large cage was modeled using a 4-fold split position (24j site), displaced 0.18 A from the cage center (6d site). The volume of the large cage is calculated to be 146 A{sup 3}, smaller than other clathrates with similar cation displacement. The sample shows n-type behavior with a maximum of -50 {mu}V/K at 823 K above which the Seebeck coefficient decreases, suggesting mixed carriers. Lattice thermal conductivity, {kappa}{sub l}, is 55 mW/K above 600 K. - Graphical abstract: Seebeck coefficient and resistivity of the type-I clathrate Ba{sub 8}Ni{sub 3.5}Si{sub 41.0}. Structure show's large displacement of the Ba cation in the large cage (6c site). Highlights: Black-Right-Pointing-Pointer Crystal structure of the Ba{sub 8}Ni{sub 3.5}Si{sub 41.0} reported. Black-Right-Pointing-Pointer Vacancies at the 2a and 6c sites. Black-Right-Pointing-Pointer Large disorder of Ba guest atom, 0.18 A from cage center. Black-Right-Pointing-Pointer Structure is compared to Ba{sub 8}Si{sub 46} and other type-I clathrates. Black-Right-Pointing-Pointer Max Seebeck of -50.7 {mu}V/C at 798.4 K, thermal conductivity {approx}55 mW/K.

Simulation of iron impurity in BaTiO3 crystals

International Nuclear Information System (INIS)

Stashans, Arvids; Castillo, Darwin

2009-01-01

Iron-doped barium titanate (BaTiO 3 ) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO 3 crystal has been discussed too.

Syntheses, crystal structure, and electronic properties of the five ABaMQ{sub 4} compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Mesbah, Adel [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); ICSM, UMR 5257 CEA / CNRS / UM / ENSCM, Site de Marcoule-Bâtiment 426, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Prakash, Jai [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Rocca, Dario; Lebègue, Sébastien [Laboratoire de Cristallographie, Résonance Magnétique, et Modélisations CRM2 (UMR UHP-CNRS 7036), Faculté des Sciences et Techniques, Université de Lorraine, BP 70239, Boulevard des Aiguillettes, 54506 Vandoeuvre-lès-Nancy Cedex (France); Beard, Jessica C.; Lewis, Benjamin A. [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States); Ibers, James A., E-mail: ibers@chem.northwestern.edu [Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113 (United States)

2016-01-15

Five new compounds belonging to the ABaMQ{sub 4} family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} are isostructural and have the TlEuPS{sub 4} structure type. They crystallize in space group D{sup 16}{sub 2h} – Pnma of the orthorhombic system. Their structure consists isolated MQ{sub 4} tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eV (RbBaPS{sub 4}), 3.4 eV (CsBaPS{sub 4}), 2.3 eV (CsBaVS{sub 4}), and 1.6 eV (RbBaVSe{sub 4}). - Graphical abstract: General view of the ABaMQ{sub 4} structure down the a axis. - Highlights: • Five new ABaMQ{sub 4} compounds were synthesized by solid-state chemistry at 1123 K. • RbBaPS{sub 4}, CsBaPS{sub 4}, CsBaVS{sub 4}, RbBaVSe{sub 4}, and CsBaVSe{sub 4} have the TlEuPS{sub 4} structure type. • The compounds are semiconductors with calculated band gaps ranging from 1.6 to 3.4 eV.

Cancer incidence in atomic bomb survivors. Part IV: Comparison of cancer incidence and mortality

International Nuclear Information System (INIS)

Ron, E.; Preston, D.L.; Mabuchi, Kiyohiko; Thompson, D.E.; Soda, Midori

1994-01-01

This report compares cancer incidence and mortality among atomic bomb survivors in the Radiation Effects Research Foundation Life Span Study (LSS) cohort. Because the incidence data are derived from the Hiroshima and Nagasaki tumor registries, case ascertainment is limited to the time (1958-1987) and geographic restrictions (Hiroshima and Nagasaki) of the registries, whereas mortality data are available from 1950-1987 anywhere in Japan. With these conditions, there were 9,014 first primary incident cancer cases identified among LSS cohort members compared with 7,308 deaths for which cancer was listed as the underlying cause of death on death certificates. When deaths were limited to those occurring between 1958-1987 in Hiroshima or Nagasaki, there were 3,155 more incident cancer cases overall, and 1,262 more cancers of the digestive system. For cancers of the oral cavity and pharynx, skin, breast, female and male genital organs, urinary system and thyroid, the incidence series was at least twice as large as the comparable mortality series. Although the incidence and mortality data are dissimilar in many ways, the overall conclusions regarding which solid cancers provide evidence of a significant dose response generally confirm the mortality findings. When either incidence or mortality data are evaluated, significant excess risks are observed for all solid cancers, stomach, colon, liver (when it is defined as primary liver cancer or liver cancer not otherwise specified on the death certificate), lung, breast, ovary and urinary bladder. No significant radiation effect is seen for cancers of the pharynx, rectum, gallbladder, pancreas, nose, larynx, uterus, prostate or kidney in either series. There is evidence of a significant excess of nonmelanoma skin cancer in the incidence data, but not in the mortality series. 19 refs., 2 figs., 10 tabs

Unravelling Local Atomic Order of the Anionic Sublattice in M(Al1-x Gax )4 with M=Sr and Ba by Using NMR Spectroscopy and Quantum Mechanical Modelling.

Science.gov (United States)

Pecher, Oliver; Mausolf, Bernhard; Peters, Volker; Lamberts, Kevin; Korthaus, Alexander; Haarmann, Frank

2016-12-05

The quasibinary section of the intermetallic phases MAl 4 and MGa 4 with M=Sr and Ba have been characterised by means of X-ray diffraction (XRD) studies and differential thermal analysis. The binary phases show complete miscibility and form solid solutions M(Al 1-x Ga x ) 4 with M=Sr and Ba. These structures crystallise in the BaAl 4 structure type with four- and five-bonded Al and/or Ga atoms (denoted as Al(4b), Al(5b), Ga(4b), and Ga(5b), respectively) that form a polyanionic Al/Ga sublattice. Solid state 27 Al NMR spectroscopic analysis and quantum mechanical (QM) calculations were applied to study the bonding of the Al centres and the influence of Al/Ga substitution, especially in the regimes with low degrees of substitution. M(Al 1-x Ga x ) 4 with M=Sr and Ba and 0.925≤x≤0.975 can be described as a matrix of the binary majority compound in which a low amount of the Ga atoms has been substituted by Al atoms. In good agreement with the QM calculations, 27 Al NMR investigations and single crystal XRD studies prove a preferred occupancy of Al(4b) for these substitution regimes. Furthermore, two different local Al environments were found, namely isolated Al(4b1) atoms and Al(4b2), due to the formation of Al(4b)-Al(4b) pairs besides isolated Al(4b) atoms within the polyanionic sublattice. QM calculations of the electric field gradient (EFG) using superlattice structures under periodic boundary conditions are in good agreement with the NMR spectroscopic results. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stellar Laboratories: 3. New Ba 5, Ba 6, and Ba 7 Oscillator Strengths and the Barium Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

Science.gov (United States)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, Jeffrey Walter

2014-01-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. Reliable Ba 5-7 oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods. We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results. For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g=7.5. The Ba abundance is 3.5 +/- 0.5 × 10(exp-4) (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 +/- 0.5 × 10(exp-6) (about 265 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely.

Simulation of iron impurity in BaTiO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids, E-mail: arvids@utpl.edu.e [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Castillo, Darwin [Grupo de Fisicoquimica de Materiales, Instituto de Quimica Aplicada, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)

2009-05-01

Iron-doped barium titanate (BaTiO{sub 3}) has been simulated taking into account cubic and tetragonal crystallographic lattices of the crystal. A quantum-chemical method based on the Hartree-Fock formalism has been used throughout the study. The calculated equilibrium structures of Fe-doped crystals reveal the defect-inward displacements of the Ti and O atoms whereas the shifts for the Ba atoms are encountered to be away with respect to the Fe impurity. According to the analysis of electron density population and electron band structure it is found that some unusual chemical bonding might take place between the Fe atom and its six adjacent O atoms. The role of Fe impurity in the ferroelectric polarization of the tetragonal BaTiO{sub 3} crystal has been discussed too.

Extended analysis of six-times ionized barium (Ba VII)

International Nuclear Information System (INIS)

Sharma, M.K.; Tauheed, A.; Rahimullah, K.

2013-01-01

The seventh spectrum of barium (Ba VII) has been investigated using experimental recordings made on a 3-m normal incidence vacuum spectrograph in Canada in the wavelength region 300–2000 Å. The data below 350 Å was supplemented from the spectrograms recorded on a 10.7-m grazing incidence spectrograph of NIST laboratory USA. The sources used to excite the spectra in both the cases were triggered spark. Previously reported levels of 5s 2 5p 2 , 5s5p 3 , 5s 2 5p5d and 5s 2 5p6s in Ba VII have been confirmed except the 1 P 1 level of 5s 2 5p5d. The analysis has been extended considerably to include new configurations 5s 2 5p6d and 5s 2 5p7s in odd parity configuration and doubly excited configurations 5s 2 5p6p, 5s 2 5p4f, 5s 2 5p5f, 5p 4 , 5s5p 2 5d and 5s5p 2 6s in even parity configuration. The 3 F 4 level of 5s 2 5p5d configuration has now been established through the identification of transitions from 5s 2 5p6p. In all, one hundred twenty-two levels have been established in this spectrum out of which ninety-two are new. A configuration interaction Hartree–Fock calculation supports the analysis. -- Highlights: ► The spectrum of Ba was recorded on a 3-m spectrograph with triggered spark source. ► Atomic transitions for Ba VII were identified to established new energy levels. ► CI calculations with relativistic corrections were made for theoretical predictions. ► Weighted oscillator strength (gf) and transition probabilities (gA) were calculated

Accurate projected augmented wave datasets for BaFe2As2

International Nuclear Information System (INIS)

Cao Chao; Wu Yuing; Hamdan, Rashid; Wang, Yunpeng; Cheng Haiping

2010-01-01

By carefully choosing parameters and including more semi-core orbitals as valence electrons, we have constructed a high-quality projected augmented wave dataset that yields results comparable to existing full-potential linearized augmented plane-wave calculations. The dataset was then applied to BaFe 2 As 2 to study the effects of different levels of structure optimization, as well as different choices of exchange-correlation functionals. It was found that the local density approximation exchange-correlation functional fails to find the correct spin-density-wave anti-ferromagnetic (SDW-AFM) ground state under full optimization, while the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional obtains the correct state but significantly overestimates the magnetism. The electronic structure of the SDW-AFM state is not very sensitive to structure optimizations with the PBE exchange-correlation functional because the positions of the As atoms are preserved under optimizations. We further investigated the Ba atom diffusion process on the BaFe 2 As 2 surface using the nudged elastic bands method. The Ba atom was found to be stable above the center of the squares formed by the surface As atoms, and a diffusion barrier of 1.2 eV was found. Our simulated scanning tunneling microscopy image suggests an ordered surface Ba atom structure, in agreement with Massee et al (2009 Phys. Rev. B 80 140507; van Heumen E et al 2010 arXiv:1009.3493v1).

Nitrogen induced ferromagnetism in Cobalt doped BaTiO3

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Chandrima Mitra

2012-09-01

Full Text Available The electronic structure and magnetism of Cobalt doped BaTiO3 (BaTi1−xCoxO3 is investigated. Substitutional Nitrogen on an Oxygen site is found to play an important role in inducing net magnetic moments in the system. The presence of a Nitrogen atom as nearest neighbour to a Cobalt atom is crucial in producing spin splitting of both the Nitrogen and Cobalt states thereby introducing a net local magnetic moment. The introduction of Nitrogen is further found to enhance ferromagnetic interactions between Cobalt atoms.

Incidence of leukemia in survivors of the atomic bomb in Hiroshima and Nagasaki, Japan

Energy Technology Data Exchange (ETDEWEB)

Folley, J H; Borges, W; Yamawaki, Takuso

1959-01-01

This document contains two reports. The aim of the first investigation was to obtain information concerning all individuals in Hiroshima and Nagasaki having onset of symptoms of leukemia or dying of the disease since the atomic explosion in 1945. Results show that: (1) There is a significant increase in the incidence of leukemia in the exposed populations of Hiroshima and Nagasaki as compared with the non-exposed populations of the two cities; (2) there is a significant increase in the incidence of leukemia within the exposed population of Hiroshima and Nagasaki in subjects exposed at distances less than 2000 meters from the hypocenter; and (3) The concept that radiation from the atomic bomb explosions in Hiroshima and Nagasaki is a leukemogenic agent in man is supported. In the second report, 10 patients were used to study the early hematologic and preclinical phases of leukemia in atomic bomb survivors. Findings are presented. 23 references, 13 figures, 15 tables.

Atomic Center interactions in BaO; Al2O3; B2O3 glasses containing silver

International Nuclear Information System (INIS)

Pontuschka, W.M.; Piccini, A.

1979-01-01

The EPR study of borate glasses, with 30% of BaO and 5% mole of silver, X-irradiated at 77 0 K, showed Ag 0 and Ag ++ centers. In addition were detected the boron electron center (BEC) and the boron hole center. The silver centers and BEC were studied in detail and the spin Hamiltonian parameters are given. The different Al 2 O 3 concentrations exerted only little influence on the tabulated constants. The Ag + 2 center was not observed, indicating that the collisions between Ag atoms are not very frequent in these glasses, even during the process of thermal bleaching. The hfs of the boron electron center suffered severe variation as one compared the spectra of base glasses and those containing silver. This is an evidence of the action of silver as a glass modifier like the alkali atoms [pt

Ultrafast atomic layer-by-layer oxygen vacancy-exchange diffusion in double-perovskite LnBaCo2O5.5+δ thin films.

Science.gov (United States)

Bao, Shanyong; Ma, Chunrui; Chen, Garry; Xu, Xing; Enriquez, Erik; Chen, Chonglin; Zhang, Yamei; Bettis, Jerry L; Whangbo, Myung-Hwan; Dong, Chuang; Zhang, Qingyu

2014-04-22

Surface exchange and oxygen vacancy diffusion dynamics were studied in double-perovskites LnBaCo2O5.5+δ (LnBCO) single-crystalline thin films (Ln = Er, Pr; -0.5 atoms in the LnBCO thin films is taking the layer by layer oxygen-vacancy-exchange mechanism. The first principles density functional theory calculations indicate that hydrogen atoms are present in LnBCO as bound to oxygen forming O-H bonds. This unprecedented oscillation phenomenon provides the first direct experimental evidence of the layer by layer oxygen vacancy exchange diffusion mechanism.

The trapping of potassium atoms by a polycrystalline tungsten surface as a function of energy and angle of incidence. ch. 1

International Nuclear Information System (INIS)

Hurkmans, A.; Overbosch, E.G.; Olander, D.R.; Los, J.

1976-01-01

The trapping probability of potassium atoms on a polycrystalline tungsten surface has been measured as a function of the angle of incidence and as a function of the energy of the incoming atoms. Below an energy of 1 eV the trapping was complete; above 20 eV only reflection occurred. The trapping probability increased with increasing angle of incidence. The measurements are compared with a simple model of the fraction of atoms initially trapped. The model, a one-dimensional cube model including a Boltzmann distribution of the velocities of oscillating surface atoms, partially explains the data. The trapping probability as a function of incoming energy is well described for normal incidence, justifying the inclusion of thermal motion of the surface atoms in the model. The angular dependence can be explained in a qualitative way, although there is a substantial discrepancy for large angles of incidence, showing the presence of surface structure. (Auth.)

High field-effect mobility at the (Sr,Ba)SnO{sub 3}/BaSnO{sub 3} interface

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, Kohei, E-mail: kfujiwara@imr.tohoku.ac.jp; Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2016-08-15

A perovskite oxide, BaSnO{sub 3}, has been classified as one of transparent conducting materials with high electron mobility, and its application for field-effect transistors has been the focus of recent research. Here we report transistor operation in BaSnO{sub 3}-based heterostructures with atomically smooth surfaces, fabricated on SrTiO{sub 3} substrates by the (Sr,Ba)SnO{sub 3} buffer technique. Indeed, modulation of band profiles at the channel interfaces with the insertion of wide bandgap (Sr,Ba)SnO{sub 3} as a barrier layer results in a significant improvement of field-effect mobility, implying effective carrier doping at the regulated heterointerface. These results provide an important step towards realization of high-performance BaSnO{sub 3}-based field-effect transistors.

Water adsorption induced in-plane domain switching on BaTiO{sub 3} surface

Energy Technology Data Exchange (ETDEWEB)

Li, X.; Bai, Y.; Su, Y. J., E-mail: yjsu@ustb.edu.cn [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Wang, B. C. [Corrosion and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Multiscale Materials Modelling group, Department of Materials and Engineering, Royal Institute of Technology, SE-10044 Stockholm (Sweden)

2015-09-07

In this study, the influences of the adsorption of water molecules on the changes in the atomic and electric structures of BaTiO{sub 3} surface were investigated using ab initio calculation. Water molecules are molecularly and dissociatively adsorbed on the BaTiO{sub 3} surface, which makes electrons transfer from water molecules to the BaTiO{sub 3} surface. The redistribution of electrons in the BaTiO{sub 3} surface layers weakens the Ba-O interactions and strengthens the Ti-O interactions, so that the Ti atom shifts in TiO{sub 2} plane, i.e., an in-plane domain switching. The adsorption of water molecules on BaTiO{sub 3} surfaces also results in a reduction in the surface rumpling.

Laserspectroscopic studies of collective properties of neutron deficient Ba nuclei

International Nuclear Information System (INIS)

Bekk, K.; Andl, A.; Goering, S.; Hanser, A.; Nowicki, G.; Rebel, H.; Schatz, G.

1979-01-01

Isotope shifts and hyperfine structure of the BaI resonance-line (lambda=553.6 nm) have been measured by dye laser induced resonance fluorescence on an atomic beam for sup(135m,129g,129m,126) Ba thus extending previous high resolution measurements of neutron deficient Ba nuclides (N - isomers sup(135m) Ba and sup(135m) Ba show a decreased staggering. Conspicuously the isomer shift of the g 7/2 + isomer sup(129m) Ba proves to be negative. The nuclear structure information is discussed in the context of gamma-spectroscopic studies of transitional nuclei with 50 [de

First-principles study of the (001) surface of cubic Ba0.5Sr0.5TiO3

International Nuclear Information System (INIS)

Wang, Yuan Xu

2008-01-01

We have theoretically investigated basic properties of the (001) surface of cubic Ba 0.5 Sr 0.5 TiO 3 (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO 2 -terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO 2 -terminated surface is much larger than that of the Ti 2 O 4 -terminated one. The surface state appears in the band structure of the Ti 2 O 4 -terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO 2 -terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Image processing for grazing incidence fast atom diffraction

Energy Technology Data Exchange (ETDEWEB)

Debiossac, Maxime; Roncin, Philippe, E-mail: philippe.roncin@u-psud.fr

2016-09-01

Grazing incidence fast atom diffraction (GIFAD, or FAD) has developed as a surface sensitive technique. Compared with thermal energies helium diffraction (TEAS or HAS), GIFAD is less sensitive to thermal decoherence but also more demanding in terms of surface coherence, the mean distance between defects. Such high quality surfaces can be obtained from freshly cleaved crystals or in a molecular beam epitaxy (MBE) chamber where a GIFAD setup has been installed allowing in situ operation. Based on recent publications by Atkinson et al. (2014) and Debiossac et al. (2014), the paper describes in detail the basic steps needed to measure the relative intensities of the diffraction spots. Care is taken to outline the underlying physical assumptions.

Thyroid cancer incidence among atomic bomb survivors, 1958-79

International Nuclear Information System (INIS)

Akiba, Suminori; Ezaki, Haruo; Ron, E.; Ishimaru, Toranosuke; Shimizu, Yukiko; Kato, Hiroo; Lubin, J.; Asano, Masahide.

1992-06-01

One hundred and twelve cases of thyroid cancer diagnosed during the period 1958-79 among the extended Life Span Study cohort in Hiroshima and Nagasaki were studied. There was a statistically significant association between thyroid cancer incidence and exposure to atomic bomb radiation. The adjusted excess relative risk (ERR) per gray was 1.1 (95% confidence interval=0.3-2.5) and the adjusted absolute risk per 10 4 PYGy was 0.59 (95% confidence interval=0.2-1.7). Based on a comparison of the deviances obtained from relative and absolute risk models, a simple linear relative risk model appeared to fit the data better than an absolute risk model; however, it would not be appropriate to conclude that the data conform strictly to a relative risk pattern. The incidence of thyroid cancer among the members of the Adult Health Study (AHS) population, who have received biennial medical examinations at the Atomic Bomb Casualty Commission and its successor the Radiation Effects Research Foundation, since 1958, was 70% higher than that among the rest of the extended LSS cohort after adjustments for city, sex, log age, calendar year, and Dosimetry System 1986 dose. There was no significant difference between the slope of the dose-response curve for AHS and non-AHS participants, although the estimated ERRs at 1 Gy for the AHS and non-AHS population were 1.6 and 0.3, respectively. The elevated risk appeared to be confined to women, and there was an increasing risk with decreasing attained age and age at exposure. (J.P.N.)

The incidence of skin cancer in Nagasaki atomic bomb survivors, 1955 - 1984

International Nuclear Information System (INIS)

Sadamori, Naoki; Mine, Mariko; Hori, Makoto; Yoshida, Hikotaro; Ichimaru, Michito; Honda, Takeo; Yoshida, Katsuro; Fujiwara, Naoko; Sadamori, Michiko.

1988-01-01

Of 20,348 persons included in the extended Life Span Study in Nagasaki, 59 persons were registered as having skin tumors during the years 1955 - 1984. Included in this study were 40 patients with histologically proven skin cancer. Thirty five patients were considered to be exposed to ≥ one cGy. There was statistically significant correlation between the incidence of skin cancer and exposure doses in both men and women (p < 0.01). Overall, the incidence of skin cancer was significantly correlated as well with the distance from the hypocenter; however, this was not significant when restricted to either men or women. Because the incidence of skin cancer has definitively increased since 1955 among A-bomb survivors, follow-up of A-bomb survivors is warranted with respect to atomic bomb-related skin cancer. (Namekawa, K.)

Surface reconstruction switching induced by tensile stress of DB steps: From Ba/Si(0 0 1)- 2 × 3 to Ba/Si(0 0 1)-4° off- 3 × 2

Science.gov (United States)

Kim, Hidong; Lkhagvasuren, Altaibaatar; Zhang, Rui; Seo, Jae M.

2018-05-01

The alkaline-earth metal adsorption on Si(0 0 1) has attracted much interest for finding a proper template in the growth of high- κ and crystalline films. Up to now on the flat Si(0 0 1) surface with double domains and single-layer steps, the adsorbed Ba atoms are known to induce the 2 × 3 structure through removing two Si dimers and adding a Ba atom per unit cell in each domain. In the present investigation, the Si(0 0 1)-4° off surface with DB steps and single domains has been employed as a substrate and the reconstruction at the initial stage of Ba adsorption has been investigated by scanning tunneling microscopy and synchrotron photoemission spectroscopy. On this vicinal and single domain terrace, a novel 3 × 2 structure rotated by 90° from the 2 × 3 structure has been found. Such a 3 × 2 structure turns out to be formed by adding a Ba atom and a Si dimer per unit cell. This results from the fact that the adsorbed Ba2+ ions with a larger ionic radius relieve tensile stress on the original Si dimers exerted by the rebonded atoms at the DB step.

Study of mortality and cancer incidence among the offspring of atomic bomb survivors. 1946-1990

International Nuclear Information System (INIS)

Yoshimoto, Yasuhiko; Mabuchi, Kiyohiko; Soda, Midori.

1996-01-01

The mortality and cancer incidence among offspring of atomic bomb survivors whose exposure dose was estimated in DS86 (Dose System 1986) were studied as one of means to evaluate the genetic influence of atomic bomb radiation. Big malformation incidence and mortality of subjects with the malformation were also studied. Death and its cause were traced from the city register and certificate of death of 67,586 offspring born in 1946-1984. Cancer was confirmed by certificate of death until 1957 and by cancer registration after 1958. Big malformation and the mortality were traced from clinical diagnostic records at birth or at necropsy, of 9-month examination after birth and of certificate of death. Comparisons were made in general and the offspring's age-related mortalities and in mortality or cancer incidence in relation to the radiation doses the parents had been exposed to. The comparisons showed no statistically significant relationships in those examined parameters. (K.H.)

Extended analysis of four-times ionized barium: (Ba V)

International Nuclear Information System (INIS)

Sharma, M.K.; Rahimullah, K.; Tauheed, A.

2014-01-01

The fifth spectrum of barium (Ba V) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph at the Antigonish laboratory (Canada) in the wavelength region 300–2080 Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration 5s 2 5p 3 6p in even parity configuration and, 5s 2 5p 3 6d and 5s 2 5p 3 7s in odd parity configuration. Previously reported levels of the ground configuration and three lowest excited configurations 5s5p 5 , 5s 2 5p 3 5d and 5s 2 5p 3 6s in Ba V have been confirmed and all the J≥4 unknown levels of 5s 2 5p 3 5d configuration have now been established through the identification of transitions from the levels of 5s 2 5p 3 6p configuration. All the levels of 5s 2 5p 3 6p configuration and thirty seven out of forty eight levels of the 5s 2 5p 3 6d and 5s 2 5p 3 7s configurations have now been established. A configuration interaction Hartree–Fock calculation supports the analysis. -- Highlights: • The spectrum of Ba was recorded on a 3-m spectrograph with triggered spark source. • CI calculations with relativistic corrections were made for theoretical predictions. • Atomic transitions for Ba V were identified to established new energy levels. • Weighted oscillator strength (gf) and transition probabilities (gA) were calculated

Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

Science.gov (United States)

Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

2014-06-01

Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: Reliable Ba v-vii oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods: We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g = 7.5. The Ba abundance is 3.5 ± 0.5 × 10-4 (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 ± 0.5 × 10-6 (about 265 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for

Crystal structure of a new natural (Ba, Nb) silicate

International Nuclear Information System (INIS)

Yamnova, N.A.; Pushcharovskii, D.Yu.; Voloshin, A.V.

1990-01-01

The structure of a new mineral Ba 3 (Ti 1.2 Nb 4.8 ) Si 4 O 25.4 is determined (166 reflections, method of least squares in anisotropic approximation, R = 0.040). The crystallographic parameters are: a = 9.03(1), c = 7.868(6) angstrom, Z = 1, space group P anti 62m. Like the previously investigated synthetic analogs Ba 3 Si 4 Nb 6 O 26 , Ba 3 Si 4 Ti 6 O 23 , and Ba 3 Si 4 Ta 6 O 26 , the structure contains a mixed framework of octahedral columns of triangular section, bound to the diortho groups [Si 2 O 7 ], of which the cavities contain the Ba atoms

O vacancy formation in (Pr/Gd)BaCo2O5.5 and the role of antisite defects

KAUST Repository

Omotayo Akande, Salawu

2017-04-20

In search for materials for intermediate temperature solid oxide fuel cells, (Pr/Gd)BaCo2O5.5 is investigated by first principles calculations. Antisite defects are considered as they may modify the electronic and O diffusion properties but are rarely studied in double perovskite oxides. Octahedrally coordinated Co atoms are shown to realize intermediate and high spin states for PrBaCo2O5.5 and GdBaCo2O5.5, respectively, while pyramidally coordinated Co atoms always have high spin. It turns out that O vacancy formation is significantly easier in PrBaCo2O5.5 than in GdBaCo2O5.5, the difference in formation energy being hardly modified by antisite defects. While pyramidally coordinated Co atoms are not affected, we show that the presence of antisite defects causes parts of the octahedrally coordinated Co atoms to switch from intermediate to high spin.

Study of radiation damage in BaTiO3, using Molecular-dynamics simulations

International Nuclear Information System (INIS)

Gonzalez, E.; Abreu, Y.; Cruz, C. M.; Pinnera, I.; Leyva, A.

2015-01-01

Molecular-dynamics (MD) simulations were used to calculate atomic displacement probability curves along main crystallographic directions in BaTiO 3 perovskite. A primary knock-on atom (PKA) with a energy range between 10 to 300 eV in principal crystallographic directions at 300 K was introduced. For each sublattice, the simulation was repeated from different initial conditions to estimate the variation in the defect formation process. The formation of Frenkel pairs vary considerably with crystallographic direction and sublattice. Major quantity oxygen defects were found for all the simulated crystallographic directions. Threshold displacement energies are calculated for each atomic specie in the BaTiO 3 material. Also simulations with SRIM code, modeling + Mn implantation in a BaTiO 3 target, at 250 keV were made. (Author)

Effects of radiation on the incidence of prostate cancer among Nagasaki atomic bomb survivors.

Science.gov (United States)

Kondo, Hisayoshi; Soda, Midori; Mine, Mariko; Yokota, Kenichi

2013-10-01

Atomic bomb survivors have been reported to have an increased risk of some cancers, especially leukemia. However, the risk of prostate cancer in atomic bomb survivors is not known to have been examined previously. This study examined the association between atomic bomb radiation and the incidence of prostate cancer among male Nagasaki atomic bomb survivors. The subjects were classified by distance from the hypocenter into a proximal group (bomb survivors who were alive in 1996. The Cox proportional hazard model was used to estimate the risk of prostate cancer development, with adjustment for age at atomic bomb explosion, attained age, smoking status, and alcohol consumption. Compared with the distal group, the proximal group had significant increased risks of total, localized, and high-grade prostate cancer (relative risk and 95% confidence interval: 1.51 [1.21-1.89]; 1.80 [1.26-2.57]; and 1.88 [1.20-2.94], respectively). This report is the first known to reveal a significant relationship between atomic bomb radiation and prostate cancer. © 2013 Japanese Cancer Association.

Atomic spin resonance in a rubidium beam obliquely incident to a transmission magnetic grating

International Nuclear Information System (INIS)

Hatakeyama, A; Goto, K

2016-01-01

We studied atomic spin resonance induced by atomic motion in a spatially periodic magnetostatic field. A rubidium atomic beam, with a velocity of about 400 m s −1 , was obliquely incident to a transmission magnetic grating that produced a spatially periodic magnetic field. The magnetic grating was formed by a magnetic thin film on a polyimide substrate that had multiple slits at 150 μm intervals. The atoms experienced field oscillation, depending on their velocity and the field period when passing through the grating, and underwent magnetic resonance. Resonance spectra obtained with a perpendicular magnetization film were in clear contrast to ones obtained with an in-plane magnetization film. The former exhibited resonance peaks at odd multiples of the frequency, determined by the velocity over the period, while the latter had dips at the same frequencies. (paper)

First-principles study of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuan Xu [Computational Materials Science Center, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

2008-06-15

We have theoretically investigated basic properties of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO{sub 2}-terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO{sub 2}-terminated surface is much larger than that of the Ti{sub 2}O{sub 4}-terminated one. The surface state appears in the band structure of the Ti{sub 2}O{sub 4}-terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO{sub 2}-terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Alignment creation in atomic ensembles by elastic electron scattering; the case of 138Ba(...6s6p 1P1) atoms

International Nuclear Information System (INIS)

Trajmar, S.; Kanik, I.; LeClair, L.R.; Khakoo, M.A.; Bray, I.; Fursa, D.; Csanak, G.

1998-01-01

We describe some of our results from a joint experimental and theoretical program concerning elastic electron scattering by 138 Ba(...6s6p 1 P 1 ) atoms. From the experimental results, we derived various scattering parameters and magnetic sublevel specific differential elastic scattering cross sections at impact energy (E 0 ) of 20.0 eV and at scattering angles (θ) of 10deg, 15deg, and 20deg. The same parameters and cross sections were calculated by the convergent close coupling (CCC) approximation and compared to the experimental results. An excellent agreement, found for the two sets of data, gave us confidence in the CCC method and allowed us to extend the angular and energy ranges for the purpose of generating integral elastic scattering cross sections needed for the deduction of the alignment creation cross sections. (J.P.N.)

Crystal structure and chemical bonding analysis of BaPtCd{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Gulo, Fakhili [Department of Chemical Education, Sriwijaya University, Inderalaya 30662, South Sumatra (Indonesia); Koehler, Juergen [Max Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

2015-03-15

The new ternary intermetallic phase, BaPtCd{sub 2}, was synthesized by solid-state reaction from direct combination of the elements in a stoichiometric mixture. The reaction was done at 850 C for 15 h, followed by an equilibration at 600 C for 4 d. The crystal structure was determined by X-ray diffraction method on a single crystal. BaPtCd{sub 2} is isotypic to MgCuAl{sub 2} and crystallizes in the orthorhombic space group Cmcm [a = 4.467(2), b = 11.143(4), c = 8.240(3) Aa, V = 410.2(3) Aa{sup 3}, and Z = 4]. Barium atoms are linked together forming zigzag chains. Cadmium atoms are bonded to each other forming six-membered rings of platinum centered boat and anti-boat conformations. BaPtCd{sub 2} contains 16 electrons per formula unit and belongs to the electron poorest compounds with MgCuAl{sub 2} type structure. Calculations based on the linear muffin-tin orbitals method in the atomic spheres approximation show that significant bonding states in BaPtCd{sub 2} are unoccupied. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Rattling of Ba-atoms in Ba8ZnxGe43-5x/8([]3-3x/8)

International Nuclear Information System (INIS)

Melnychenko, N.; Grytsiv, A.; Rotter, M.; Rogl, P.; Devishvili, A.

2006-01-01

Full text: In order to improve the figure of merit of thermoelectric materials, one of the key parameters to be minimized is the lattice thermal conductivity. It is thus essential for the design of new thermoelectric materials to understand the lattice dynamics, especially the scattering mechanism of low energy phonons. The present paper describes formation, phase relations at subsolidus temperatures as well as at 800 o C, crystal chemistry and physical properties of a series of ternary clathrates as part of the solid solution, Ba 8 Zn x (Ge 43-5x/8[]3-3x/8 ), deriving from binary Ba 8 Ge 43 []3 with a solubility limit of 8 Zn per formula unit at 800 o C. Structural investigations in all cases confirm cubic primitive symmetry with a lattice parameter a ∼ 1.1 nm consistent with the space group type Pm-3n. Studies of transport coefficients evidence electrons as the majority charge carriers in the systems. Thermal conductivity exhibits a pronounced low temperature maximum, dominated by the lattice contribution, while at higher temperatures the electronic part gains weight. Inelastic neutron scattering experiments are used to study the phonon spectrum for Ba 8 Zn 8 Ge 38 . (author)

AEMnSb2 (AE=Sr, Ba): a new class of Dirac materials

International Nuclear Information System (INIS)

Farhan, M Arshad; Lee, Geunsik; Shim, Ji Hoon

2014-01-01

The Dirac fermions of Sb square net in AEMnSb 2 (AE=Sr, Ba) are investigated by using first-principles calculation. BaMnSb 2 contains Sb square net layers with a coincident stacking of Ba atoms, exhibiting Dirac fermion behavior. On the other hand, SrMnSb 2 has a staggered stacking of Sr atoms with distorted zig-zag chains of Sb atoms. Application of hydrostatic pressure on the latter induces a structural change from a staggered to a coincident arrangement of AE ions accompanying a transition from insulator to a metal containing Dirac fermions. The structural investigations show that the stacking type of cation and orthorhombic distortion of Sb layers are the main factors to decide the crystal symmetry of the material. We propose that the Dirac fermions can be obtained by controlling the size of cation and the volume of AEMnSb 2 compounds. (fast track communication)

Cation-Poor Complex Metallic Alloys in Ba(Eu)-Au-Al(Ga) Systems: Identifying the Keys that Control Structural Arrangements and Atom Distributions at the Atomic Level.

Science.gov (United States)

Smetana, Volodymyr; Steinberg, Simon; Mudryk, Yaroslav; Pecharsky, Vitalij; Miller, Gordon J; Mudring, Anja-Verena

2015-11-02

Four complex intermetallic compounds BaAu(6±x)Ga(6±y) (x = 1, y = 0.9) (I), BaAu(6±x)Al(6±y) (x = 0.9, y = 0.6) (II), EuAu6.2Ga5.8 (III), and EuAu6.1Al5.9 (IV) have been synthesized, and their structures and homogeneity ranges have been determined by single crystal and powder X-ray diffraction. Whereas I and II originate from the NaZn13-type structure (cF104-112, Fm3̅c), III (tP52, P4/nbm) is derived from the tetragonal Ce2Ni17Si9-type, and IV (oP104, Pbcm) crystallizes in a new orthorhombic structure type. Both I and II feature formally anionic networks with completely mixed site occupation by Au and triel (Tr = Al, Ga) atoms, while a successive decrease of local symmetry from the parental structures of I and II to III and, ultimately, to IV correlates with increasing separation of Au and Tr on individual crystallographic sites. Density functional theory-based calculations were employed to determine the crystallographic site preferences of Au and the respective triel element to elucidate reasons for the atom distribution ("coloring scheme"). Chemical bonding analyses for two different "EuAu6Tr6" models reveal maximization of the number of heteroatomic Au-Tr bonds as the driving force for atom organization. The Fermi levels fall in broad pseudogaps for both models allowing some electronic flexibility. Spin-polarized band structure calculations on the "EuAu6Tr6" models hint to singlet ground states for europium and long-range magnetic coupling for both EuAu6.2Ga5.8 (III) and EuAu6.1Al5.9 (IV). This is substantiated by experimental evidence because both compounds show nearly identical magnetic behavior with ferromagnetic transitions at TC = 6 K and net magnetic moments of 7.35 μB/f.u. at 2 K. The effective moments of 8.3 μB/f.u., determined from Curie-Weiss fits, point to divalent oxidation states for europium in both III and IV.

Cancer incidence in the population of Nagasaki city 30 years after atomic bombing

International Nuclear Information System (INIS)

Okuyama, Shinichi; Mishina, Hitoshi

1988-01-01

In order to attest the evolutionary hypothesis of non-epithelial-epithelial tumor shift (Okuyama and Mishina 1986), the published cancer incidence data for the population of Nagasaki City during the period of 1973-1977 was studied along with appropriate control populations of Fukuoka City, and Miyagi and Osaka prefectures. Significant increments of non-epithelial tumors including leukemias, and epithelial tumors such as cervical cancers and choriocarcinomas were observed. An inference was made to the post-atomic bomb radiation carcinogenesis that different organ systems responded to that irradiation with different oncogenic patterns: Neoplasms of the pre-vertebral organs (non-epithelial organ systems) were the first to react and tapered long (curve type I); Tumors of the vertebral but pre-mammalian (those of the digestive tract, respiratory and thyroid) could have formed two separate peaks, one for the early and high dosage and the other for the late and low dosage (II); With breast cancer or the mammalian symbol tumor, there was a single peak reflecting the cohort of reproductives (III). The evolutionary and phylogenetic progression could have taken place from I through III. Thus, cancer incidence analysis may be helpful in deciphering the atomic bomb radiation carcinogenesis. (author)

Redetermination of clinobarylite, BaBe2Si2O7

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Adrien J. Di Domizio

2012-10-01

Full Text Available Clinobarylite, ideally BaBe2Si2O7 (chemical name barium diberyllium disilicate, is a sorosilicate mineral and dimorphic with barylite. It belongs to a group of compounds characterized by the general formula BaM2+2Si2O7, with M2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobarylite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia. The structure of clinobarylite can be considered as a framework of BeO4 and SiO4 tetrahedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO4 tetrahedra share corners, forming chains parallel to the c axis, which are interlinked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations (site symmetry m.. are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si—Obr (bridging O atom, at site symmetry m.. bond length, the Si—Onbr (non-bridging O atoms bond lengths, and the Si—O—Si angle within the Si2O7 unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004. N. Jb. Miner. Mh. pp. 373–384].

Redetermination of clinobaryl-ite, BaBe(2)Si(2)O(7).

Science.gov (United States)

Domizio, Adrien J Di; Downs, Robert T; Yang, Hexiong

2012-10-01

Clinobaryl-ite, ideally BaBe(2)Si(2)O(7) (chemical name barium diberyllium disilicate), is a sorosilicate mineral and dimorphic with baryl-ite. It belongs to a group of compounds characterized by the general formula BaM(2+) (2)Si(2)O(7), with M(2+) = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobaryl-ite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia). The structure of clinobaryl-ite can be considered as a framework of BeO(4) and SiO(4) tetra-hedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO(4) tetra-hedra share corners, forming chains parallel to the c axis, which are inter-linked by the Si(2)O(7) units oriented parallel to the a axis. The Ba(2+) cations (site symmetry m..) are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si-O(br) (bridging O atom, at site symmetry m..) bond length, the Si-O(nbr) (non-bridging O atoms) bond lengths, and the Si-O-Si angle within the Si(2)O(7) unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004 ▶). N. Jb. Miner. Mh. pp. 373-384].

Hexagonal perovskites with cationic vacancies. 21. Structure of Ba/sub 4/Nb/sub 2/WvacantO/sub 12/ and Ba/sub 3/LaNb/sub 3/vacantO/sub 12/

Energy Technology Data Exchange (ETDEWEB)

Rother, H J; Kemmler-Sack, S; Treiber, U; Cyris, W R [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-07-01

Compounds of type Ba/sub 4/M/sub 2/sup(V)WvacantO/sub 12/ and Ba/sub 3/LaM/sub 3/sup(V)vacantO/sub 12/ with Msup(V) = Nb, Ta belong to the group of rhombohedral 12 L stacking polytypes (space group R-3m, sequence (hhcc)/sub 3/). The structure determinations on powder patterns for the Nb compounds gave a refined, intensity related R' value of 6.3% (Ba/sub 4/Nb/sub 2/WvacantO/sub 12/) and 6.6% (Ba/sub 3/LaNb/sub 3/vacantO/sub 12/). The octahedral net consists of blocks of three face connected octahedra with a central void (M/sub 2/vacantO/sub 12/ unit), which are linked to each other through single corner sharing octahedra. In both compounds the M atoms in the M/sub 2/vacantO/sub 12/ groups are displaced in the direction of the central void. The A atoms move in the same direction but the dislocation for A in the hexagonal packed sheets (neighbouring the vacancies) is stronger than in the cubic packed AO/sub 3/ sheets. The results of the vibrational spectroscopic investigations are reported for Ba/sub 4/Nb/sub 2/WvacantO/sub 12/, Ba/sub 4/Ta/sub 2/WvacantO/sub 12/, Ba/sub 3/LaNb/sub 3/vacantO/sub 12/ and Ba/sub 4/CeW/sub 2/vacantO/sub 12/; they are discussed in connection with the factor group analysis.

Incident angle dependence of reactions between graphene and hydrogen atom by molecular dynamics simulation

International Nuclear Information System (INIS)

Saito, Seiki; Nakamura, Hiroaki; Ito, Atsushi

2010-01-01

Incident angle dependence of reactions between graphene and hydrogen atoms are obtained qualitatively by classical molecular dynamics simulation under the NVE condition with modified Brenner reactive empirical bond order (REBO) potential. Chemical reaction depends on two parameters, i.e., polar angle θ and azimuthal angle φ of the incident hydrogen. From the simulation results, it is found that the reaction rates strongly depend on polar angle θ. Reflection rate becomes larger with increasing θ, and the θ dependence of adsorption rate is also found. The θ dependence is caused by three dimensional structure of the small potential barrier which covers adsorption sites. φ dependence of penetration rate is also found for large θ. (author)

BaSi2 formation mechanism in thermally evaporated films and its application to reducing oxygen impurity concentration

Science.gov (United States)

Hara, Kosuke O.; Yamamoto, Chiaya; Yamanaka, Junji; Arimoto, Keisuke; Nakagawa, Kiyokazu; Usami, Noritaka

2018-04-01

Thermal evaporation is a simple and rapid method to fabricate semiconducting BaSi2 films. In this study, to elucidate the BaSi2 formation mechanism, the microstructure of a BaSi2 epitaxial film fabricated by thermal evaporation has been investigated by transmission electron microscopy. The BaSi2 film is found to consist of three layers with different microstructural characteristics, which is well explained by assuming two stages of film deposition. In the first stage, BaSi2 forms through the diffusion of Ba atoms from the deposited Ba-rich film to the Si substrate while in the second stage, the mutual diffusion of Ba and Si atoms in the film leads to BaSi2 formation. On the basis of the BaSi2 formation mechanism, two issues are addressed. One is the as-yet unclarified reason for epitaxial growth. It is found important to quickly form BaSi2 in the first stage for the epitaxial growth of upper layers. The other issue is the high oxygen concentration in BaSi2 films around the BaSi2-Si interface. Two routes of oxygen incorporation, i.e., oxidation of the Si substrate surface and initially deposited Ba-rich layer by the residual gas, are identified. On the basis of this knowledge, oxygen concentration is decreased by reducing the holding time of the substrate at high temperatures and by premelting of the source. In addition, X-ray diffraction results show that the decrease in oxygen concentration can lead to an increased proportion of a-axis-oriented grains.

Negative atomic halogens incident on argon and molecular nitrogen: electron detachment studies

International Nuclear Information System (INIS)

Jalbert, G; Medina, A; Magalhaes, S D; Wolff, W; Barros, A L F de; Carrilho, P; Rocha, A B; Faria, N V de Castro

2007-01-01

During the last years we have measured total detachment cross sections of atomic and cluster anions colliding with gases in the velocity range of 0.2 to 1.8 a.u. In particular, we measured negative atomic halogens incident on argon and molecular nitrogen. These last data are for the first time analyzed using the simple semi-classical model that we have developed. For that purpose, the values of elastic plus inelastic cross sections for impact of free electrons on Ar and N 2 , the latter showing a shape resonance, convoluted with the anion's outermost electron momentum distribution yielded the overall shape of the anion cross sections. Inclusion of a velocity independent additive term, interpreted as an effective area of the collision region, led to accurate absolute cross section values. The high affinity of the halogens and the existence of a not well described resonance in the e-N 2 collision, are characteristics that may be used to delimit the scope and validity of the model

Non-observation of 12C cluster decay of 114Ba

International Nuclear Information System (INIS)

Guglielmetti, A.; Bonetti, R.; Poli, G.; Collatz, R.; Hu, Z.; Kirchner, R.; Roeckl, E.; Gunn, N.; Price, P.B.; Weaver, B.A.; Westphal, A.; California Univ., Berkeley, CA; Szerypo, J.

1997-10-01

By means of the on-line mass separator at Gesellschaft fuer Schwerionenforschung, Darmstadt, we produced 114 Ba through the 58 Ni( 58 Ni,2n) reaction, separated it as a 114 Ba 19 F + beam, and implanted it into a stopper foil positioned in the center of an array of track detectors, which were used to search for 12 C radioactivity of 114 Ba. A total number of (5.4±1.7).10 4 114 Ba atoms were implanted. No 12 C event was found after a total exposure time of 116 hours, corresponding to a 58 Ni beam dose of 1.3.10 17 . The resulting upper limit of 3.4.10 -5 (84% c. 1.) for the branching ratio for 12 C decay of 114 Ba is considerably lower than the limits obtained in previous experiments, which represents an inconsistency at levels of more than 90%. A semiempirical estimate of 19.3 MeV for the upper limit of the Q-value for 12 C decay of 114 Ba is derived. (orig.)

Isothermal cross-sections of Sr-Al-Ge and Ba-Al-Ge systems at 673 K

International Nuclear Information System (INIS)

Kutsenok, N.L.; Yanson, T.I.

1987-01-01

X-ray and microstructural analyses are used to study phase equilibria in Sr-Al-Ge and Ba-Al-Ge systems. Existence of SrAl 2 Ge 2 , Sr(Al, Ge) 2 Ba(Al, Ge) 2 , Sr 3 Al 2 Ge 2 , Ba 3 Al 2 Ge 2 ternary compounds is confirmed, a new BaGe 4 binary compound and also new ternary compounds of approximate composition Sr 57 Al 30 Ge 13 and Ba 20 Al 40 Ge 40 , which crystal structure is unknown, are detected. Aluminium solubility in SrAl 4 and BaAl 4 binary compounds (0.05 atomic fraction) is determined. Ba(Al, Ge) 2 compound homogeneity region is defined more exactly (aluminium content varies from 0.27 to 0.51 at. fractions)

Atomic and electronic structures of BaHfO3-doped TFA-MOD-derived YBa2Cu3O7−δ thin films

International Nuclear Information System (INIS)

Molina-Luna, Leopoldo; Duerrschnabel, Michael; Turner, Stuart; Martinez, Gerardo T; Van Aert, Sandra; Van Tendeloo, Gustaaf; Erbe, Manuela; Holzapfel, Bernhard

2015-01-01

Tailoring the properties of oxide-based nanocomposites is of great importance for a wide range of materials relevant for energy technology. YBa 2 Cu 3 O 7−δ (YBCO) superconducting thin films containing nanosized BaHfO 3 (BHO) particles yield a significant improvement of the magnetic flux pinning properties and a reduced anisotropy of the critical current density. These films were prepared by chemical solution deposition (CSD) on (100) SrTiO 3 (STO) substrates yielding critical current densities up to 3.6 MA cm −2 at 77 K and self-field. Transport in-field J c measurements demonstrated a high pinning force maximum of around 6 GN/m 3 for a sample annealed at T = 760 °C that has a doping of 12 mol% of BHO. This sample was investigated by scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) yielding strain and spectral maps. Spherical BHO nanoparticles of 15 nm in size were found in the matrix, whereas the particles at the interface were flat. A 2 nm diffusion layer containing Ti was found at the YBCO (BHO)/STO interface. Local lattice deformation mapping at the atomic scale revealed crystal defects induced by the presence of both sorts of BHO nanoparticles, which can act as pinning centers for magnetic flux lines. Two types of local lattice defects were identified and imaged: (i) misfit edge dislocations and (ii) Ba-Cu-Cu-Ba stacking faults (Y-248 intergrowths). The local electronic structure and charge transfer were probed by high energy resolution monochromated electron energy-loss spectroscopy. This technique made it possible to distinguish superconducting from non-superconducting areas in nanocomposite samples with atomic resolution in real space, allowing the identification of local pinning sites on the order of the coherence length of YBCO (∼1.5 nm) and the determination of 0.25 nm dislocation cores. (paper)

An Atomic Gravitational Wave Interferometric Sensor (AGIS)

OpenAIRE

Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet

2008-01-01

We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10 m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with ba...

Surface morphology and in-plane-epitaxy of SmBa2Cu3O7-δ films on SrTiO3 (001) substrates studied by STM and grazing incidence x-ray diffraction

DEFF Research Database (Denmark)

Jiang, Q.D.; Smilgies, D.M.; Feidenhans'l, R.

1996-01-01

The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films as ...... films above h(c2), introduction of screw dislocations leads to spiral growth.......The surface morphology and in-plane epitaxy of thin films of SmBa(2)Cu3O(7-delta) (Sm-BCO) grown on SrTiO3 (001) substrates with various thicknesses have been investigated by scanning tunneling microscopy (STM) and grazing incidence x-ray diffraction (GIXRD). As revealed by GIXRD, SmBCO films...... substrate. Three different types of surface morphology were observed by STM with increasing film thickness h: a) 2D growth for hh(c2). With GIXRD, a density modulation is observed in the films with a thickness below h(c2). For thicker...

Redetermination of clinobaryl­ite, BaBe2Si2O7

Science.gov (United States)

Domizio, Adrien J. Di; Downs, Robert T.; Yang, Hexiong

2012-01-01

Clinobaryl­ite, ideally BaBe2Si2O7 (chemical name barium diberyllium disilicate), is a sorosilicate mineral and dimorphic with baryl­ite. It belongs to a group of compounds characterized by the general formula BaM 2+ 2Si2O7, with M 2+ = Be, Mg, Fe, Mn, Zn, Co, or Cu, among which the Be-, Fe-, and Cu-members have been found in nature. The crystal structure of clinobaryl­ite has been re-examined in this study based on single-crystal X-ray diffraction data collected from a natural sample from the type locality (Khibiny Massif, Kola Peninsula, Russia). The structure of clinobaryl­ite can be considered as a framework of BeO4 and SiO4 tetra­hedra, with one of the O atoms coordinated to two Be and one Si, one coordinated to two Si, and two O atoms coordinated to one Si and one Be atom. The BeO4 tetra­hedra share corners, forming chains parallel to the c axis, which are inter­linked by the Si2O7 units oriented parallel to the a axis. The Ba2+ cations (site symmetry m..) are in the framework channels and are coordinated by eleven O atoms in form of an irregular polyhedron. The Si—Obr (bridging O atom, at site symmetry m..) bond length, the Si—Onbr (non-bridging O atoms) bond lengths, and the Si—O—Si angle within the Si2O7 unit are in marked contrast to the corresponding values determined in the previous study [Krivovichev et al. (2004 ▶). N. Jb. Miner. Mh. pp. 373–384]. PMID:23125568

Identification of the neutron-rich nuclides /sup 147; 148/Ba and half- life determination of the heavy isotopes of Rb, Sr, Y, Cs, Ba and La

CERN Document Server

Amiel, S; Nir-El, Y; Shmid, M

1976-01-01

The neutron nuclides /sup 147; 148/Ba were produced in the thermal neutron induced fission of /sup 235/U. A new surface ionization integrated target ion source operating at temperatures in the region of 1800 degrees C permits the measurement of half-lives of isotopes down to about 0.1 sec due to the very fast release of atoms from the target. Isotopes of Rb, Sr, Cs, and Ba were separated by positive surface ionization and their half-lives measured using beta activity detected by a silicon surface barrier detector with a depletion depth of 300 mu . The isotopes /sup 147/Ba and /sup 148/Ba were identified for the first time and their half-lives were found to be 0.72+or-0.07 sec and 0.47+or-0.20 sec, respectively. (0 refs).

Atomically layer-by-layer diffusion of oxygen/hydrogen in highly epitaxial PrBaCo{sub 2}O{sub 5.5+δ} thin films

Energy Technology Data Exchange (ETDEWEB)

Bao, Shanyong; Xu, Xing; Enriquez, Erik; Mace, Brennan E.; Chen, Garry; Kelliher, Sean P.; Chen, Chonglin, E-mail: cl.chen@utsa.edu [Department of Physics and Astronomy, University of Texas, San Antonio, Texas 78249 (United States); Zhang, Yamei [Department of Physics, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003 (China); Whangbo, Myung-Hwan [North Carolina State University, Raleigh, North Carolina 27695-8204 (United States); Dong, Chuang; Zhang, Qinyu [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education, Dalian University of Technology, Dalian 116024 (China)

2015-12-14

Single-crystalline epitaxial thin films of PrBaCo{sub 2}O{sub 5.5+δ} (PrBCO) were prepared, and their resistance R(t) under a switching flow of oxidizing and reducing gases were measured as a function of the gas flow time t in the temperature range of 200–800 °C. During the oxidation cycle under O{sub 2}, the PrBCO films exhibit fast oscillations in their dR(t)/dt vs. t plots, which reflect the oxidation processes, Co{sup 2+}/Co{sup 3+} → Co{sup 3+} and Co{sup 3+} → Co{sup 3+}/Co{sup 4+}, that the Co atoms of PrBCO undergo. Each oscillation consists of two peaks, with larger and smaller peaks representing the oxygen/hydrogen diffusion through the (BaO)(CoO{sub 2})(PrO)(CoO{sub 2}) layers of PrBCO via the oxygen-vacancy-exchange mechanism. This finding paves a significant avenue for cathode materials operating in low-temperature solid-oxide-fuel-cell devices and for chemical sensors with wide range of operating temperature.

Surface geometry of BaO on W(100): A surface-extended x-ray-absorption fine-structure study

International Nuclear Information System (INIS)

Shih, A.; Hor, C.; Elam, W.; Kirkland, J.; Mueller, D.

1991-01-01

A surface-extended x-ray-absorption fine-structure study of ordered monolayers of coadsorbed barium and oxygen on a single-crystal W(100) surface is described. A (√2 x √2 )R45 degree structure with a stoichiometric barium-to-oxygen ratio, and a (2 √2 x √2 )R45 degree structure with a nearly 1:2 barium-to-oxygen atomic ratio both form on W(100). The surface-extended x-ray-absorption fine-structure results indicate that all the barium and oxygen atoms are nearly coplanar in the (√2 x √2 )R45 degree overlayer. The Ba-to-O distance in this overlayer is 3.20 ±0.05 A and β=82 degree ±5 degree, where β is the angle between the Ba-O internuclear axis and the surface normal. For the (2 √2 x √2 )R45 degree overlayer, there are two types of oxygen sites. Oxygen atoms nearly coplanar with the barium atoms are also present in these films with a Ba-to-O distance of 3.27±0.05 A and β=75±4 degree. Additional oxygen atoms lie outside the barium plane at a distance 2.03±0.05 A and β=23±10 degree from the nearest barium atoms

Structural, electronic and optical characteristics of SrGe{sub 2} and BaGe{sub 2}: A combined experimental and computational study

Energy Technology Data Exchange (ETDEWEB)

Kumar, Mukesh, E-mail: mkgarg79@gmail.com [Environmental Remediation Materials Unit, National Institute for Materials Science, Ibaraki 305-0044 (Japan); Umezawa, Naoto [Environmental Remediation Materials Unit, National Institute for Materials Science, Ibaraki 305-0044 (Japan); Imai, Motoharu [Superconducting Properties Unit, National Institute for Materials Science, Ibaraki 305-0047 (Japan)

2015-05-05

Highlights: • Charge transfer between cation and anion atoms observed first time in digermandies. • Study yields a band gap of ∼1 eV and ∼0.85 eV for SrGe{sub 2} and BaGe{sub 2}, respectively. • Band gap decrease with the application of hydrostatic pressure. • Localized cation d states lead to a large absorption coefficient (>7.5 × 10{sup 4} cm{sup −1}). - Abstract: SrGe{sub 2} and BaGe{sub 2} were characterized for structural, electronic and optical properties by means of diffuse reflectance and first-principles density functional theory. These two germanides crystallize in the BaSi{sub 2}-type structure, in which Ge atoms are arranged in tetrahedral configuration. The calculation indicates a charge transfer from Sr (or Ba) atoms to Ge atoms along with the formation of covalent bonds among Ge atoms in Ge tetrahedral. The computational results confirm that these two germanies are Zintl phase described as Sr{sub 2}Ge{sub 4} (or Ba{sub 2}Ge{sub 4}), which are characterized by positively charged [Sr{sub 2} (or Ba{sub 2})]{sup 2.59+} and negatively charged [Ge{sub 4}]{sup 2.59−} units acting as cation and anion, respectively. These compounds are indirect gap semiconductors with band gap estimated to be E{sub g} = 1.02 eV for BaGe{sub 2} and E{sub g} = 0.89 eV for SrGe{sub 2} which are in good agreement with our experimental measured values (E{sub g} = 0.97 eV for BaGe{sub 2} and E{sub g} = 0.82 eV for SrGe{sub 2}). Our calculations demonstrate that the band gaps are narrowed by application of hydrostatic pressure; the pressure coefficients are estimated to be −10.54 for SrGe{sub 2} and −10.06 meV/GPa for BaGe{sub 2}. Optical properties reveal that these compounds have large absorption coefficient (∼7.5 × 10{sup 4} cm{sup −1} at 1.5 eV) and the estimated high frequency (static) dielectric constant are, ε{sub ∞}(ε{sub 0}) ≈ 12.8(20.97) for BaGe{sub 2} and ε{sub ∞}(ε{sub 0}) ≈ 14.27(22.87) for SrGe{sub 2}.

Surface structures and dielectric response of ultrafine BaTiO3 particles

International Nuclear Information System (INIS)

Jiang, B.; Peng, J.L.; Bursill, L.A.

1998-01-01

Characteristic differences are observed for the dielectric response and microstructures of BaTiO 3 nanoscale fine powders prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. Atomic resolution images of both varieties showed a high density of interesting surface steps and facets. Computer simulated images of surface structure models showed that the outer (100) surface was typically a BaO layer and that at corners and ledges the steps are typically finished with Ba+2 ions; i.e. the surfaces and steps are Ba-rich. Otherwise the surfaces were typically clean and free of amorphous layers. The relationship between the observed surfaces structures and theoretical models for size effects on the dielectric properties is discussed. (authors)

Microwave ionization and excitation of Ba Rydberg atoms

International Nuclear Information System (INIS)

Eichmann, U.; Dexter, J.L.; Xu, E.Y.; Gallagher, T.F.

1989-01-01

We have investigated ionization and excitation of the Ba 6sn s 1 S 0 and 6snd 1,3 D 2 series in strong microwave fields. The observed microwave ionization threshold fields, scaling as 0.28 n -5 , and the state mixing fields cannot be completely explained in terms of a single cycle Landau-Zener model. However, by taking into account multiphoton resonant transitions driven by many cycles of the microwave field we have been able to interpret the data. In particular multi-photon transitions have been found to be responsible for apparent resonance structures and for the unexpectedly low mixing fields. Not surprisingly, doubly excited valence states introduce irregularities into both the microwave ionization and the state mixing field values. (orig.)

Structural, optical and electronic properties of K2Ba(NO3)4 crystal

Science.gov (United States)

Isaenko, L. I.; Korzhneva, K. E.; Goryainov, S. V.; Goloshumova, A. A.; Sheludyakova, L. A.; Bekenev, V. L.; Khyzhun, O. Y.

2018-02-01

Nitrate crystals reveal nonlinear optical properties and could be considered as converters of laser radiation in the short-wave region. The conditions for obtaining and basic properties of K2Ba(NO3)4 double nitrate crystals were investigated. Crystal growth was implemented by slow cooling in the temperature range of 72-49 °C and low rate evaporation. The structural analysis of K2Ba(NO3)4 formation on the basis of two mixed simple nitrate structures is discussed. The main groups of oscillations in K2Ba(NO3)4 crystal were revealed using Raman and IR spectroscopy, and the table of vibrations for this compound was compiled. The electronic structure of K2Ba(NO3)4 was elucidated in the present work from both experimental and theoretical viewpoints. In particular, X-ray photoelectron spectroscopy (XPS) was employed in the present work to measure binding energies of the atoms constituting the titled compound and its XPS valence-band spectrum for both pristine and Ar+ ion-bombarded surfaces. Further, total and partial densities of states of constituent atoms of K2Ba(NO3)4 have been calculated. The calculations reveal that the O 2p states dominate in the total valence-band region of K2Ba(NO3)4 except of its bottom, where K 3p and Ba 5p states are the principal contributors, while the bottom of the conduction band is composed mainly of the unoccupied O 2p states, with somewhat smaller contributions of the N 2p∗ states as well. With respect to the occupation of the valence band by the O 2p states, the present band-structure calculations are confirmed by comparison on a common energy scale of the XPS valence-band spectrum and the X-ray emission O Kα band for the K2Ba(NO3)4 crystal under study. Furthermore, the present calculations indicate that the K2Ba(NO3)4 compound is a direct-gap material.

Carcinogenesis model analysis for breast cancer incidence among atomic bomb survivors and the implications for cancer risk estimate for radiological protection

International Nuclear Information System (INIS)

Kai, Michiaki; Kusama, Tomoko

2000-01-01

Breast cancer incidence is the highest risk due to radiation among atomic bomb survivors. The excess relative risk of the early-onset breast cancer seems to be remarkably high for the youngest age-at-exposure groups. The cancer risk estimate of breast cancer is a current issue in radiological protection. We used a two-stage stochastic model for carcinogenesis to analyze the breast cancer incidence among atomic bomb survivors (Kai, et al. Radiat. Res. 1997). Our purpose is to examine the dependence of radiation risk on age at exposure using the two-stage model and how to transfer it to other populations for radiological protection. We fitted the model assuming that radiation acts as an initiator and that the rate of radiation-induced mutation and background initiation mutation leading to baseline cancer are additive. We took two age-dependence, not attained age but age at exposure, of the spontaneous process into account. First, age-dependence of spontaneous initiation was expressed by a linear model. We also modeled the age-dependence of spontaneous net growth rate of initiated cells by a linear function. As far as radiation-induced initiation is concerned, we took a stepwise function other than a liner function into account. The analysis did not show that the radiation mutation for the youngest age-at-exposure groups below age 10 was higher than for the older groups. Furthermore, the incidence of female breast cancer in Japan is increasing and the birth cohort effect can be observed in atomic bomb survivors. Our model assumed that an acute exposure to atomic radiation can only initiate cancers and do not influence other stages of carcinogenesis, whereas spontaneous initiation and promotion are age-dependent to consider birth cohort effects. When these cohort effects are properly accounted for, the shape of the age-specific incidence curve in Japan is remarkably similar to the age-specific incidence in western populations (shown in figure). Recently Little and

Improvement of BaO:B2O3:Fly ash glasses: Radiation shielding, physical and optical properties

International Nuclear Information System (INIS)

Tuscharoen, S.; Kaewkhao, J.; Limkitjaroenporn, P.; Limsuwan, P.; Chewpraditkul, W.

2012-01-01

Highlights: ► BaO:B 2 O 3 :Fly ash glasses have been improved in radiation Shielding, physical and optical properties. ► The visible light transmission of RHA glass was better than SiO 2 . ► At all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete. -- Abstract: Rice husk ash glass (RHA-glass) of composition xBaO:(80 − x)B 2 O 3 :20RHA where x = 45, 50, 55, 60, 65 and 70 wt.% have been prepared using melt-quenching method and investigated on their optical, physical and gamma-rays shielding properties. The densities of these glass samples were increased with increasing of BaO content, due to higher molecular weight of BaO comparing with B 2 O 3 . The molar volume of these glasses was increased with increasing content of BaO; BaO acts as modifier to increase the loose packing. The visible light transmission of RHA glass was better than SiO 2 glass prepared in same formula and preparing condition. The experimental values of gamma ray shielding properties such as; mass attenuation coefficients, atomic cross sections and effective atomic numbers, were found in good agreement with the theoretical values as calculated from WinXCom. Moreover the glass system at all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete.

Oncohematological diseases in the Vale do Paraíba, State of São Paulo: demographic aspects, prevalences and incidences

Directory of Open Access Journals (Sweden)

Fernando Callera

2011-01-01

Full Text Available BACKGROUND: Based on the necessity of detailed information that supports effective strategies to improve cancer outcomes in the different regions of Brazil, the aims of this study were to report demographic aspects and to calculate the prevalence and incidence rates of oncohematological diseases in the region of Vale do Paraíba. METHODS: This is a multicentric prospective study carried out from October 2009 to March 2010. A total of 500 over 19-year-old patients were enrolled. Data such as type of healthcare insurance, gender, age, ethnic classification, place of residence, schooling, income, body mass index, new cases and the period between the first symptoms and a definite diagnosis were collected. The prevalence and incidence rates were calculated according to an estimated number of 1,319,800 inhabitants. RESULTS: The prevalence and incidence rates per 100,000 inhabitants in the period of six months were, respectively: acute myeloid leukemia 1.5 and 0.7; acute lymphoblastic leukemia 0.5 and 0.1; chronic lymphocytic leukemia 2.4 and 0.4; chronic myeloid leukemia 6.2 and 0.8; Hodgkin's lymphoma 2.9 and 0.9; non-Hodgkin lymphoma 9.8 and 4.3; multiple myeloma 5.7 and 0.7; myelodysplastic syndromes 2.1 and 0.2 and myeloproliferative syndromes 5.1 and 0.3. CONCLUSION: Giving the paucity of data in this field of investigation, our data may be useful for comparisons with those of other regions of Brazil and will assist in the implementation of treatment programs of oncohematological diseases in this region.

Trigermanides AEGe{sub 3} (AE = Ca, Sr, Ba). Chemical bonding and superconductivity

Energy Technology Data Exchange (ETDEWEB)

Castillo, Rodrigo; Schnelle, Walter; Baranov, Alexey I.; Burkhardt, Ulrich; Bobnar, Matej; Cardoso-Gil, Raul; Schwarz, Ulrich; Grin, Yuri [Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany)

2016-08-01

The crystal structures of the trigermanides AEGe{sub 3}(tI32) (AE = Ca, Sr, Ba; space group I4/mmm, for SrGe{sub 3}: a = 7.7873(1), c = 12.0622(3) Aa) comprise Ge{sub 2} dumbbells forming layered Ge substructures which enclose embedded AE atoms. The chemical bonding analysis by application of the electron localizability approach reveals a substantial charge transfer from the AE atoms to the germanium substructure. The bonding within the dumbbells is of the covalent two-center type. A detailed analysis of SrGe{sub 3} reveals that the interaction on the bond-opposite side of the Ge{sub 2} groups is not lone pair-like - as it would be expected from the Zintl-like interpretation of the crystal structure with anionic Ge layers separated by alkaline-earth cations - but multi-center strongly polar between the Ge{sub 2} dumbbells and the adjacent metal atoms. Similar atomic interactions are present in CaGe{sub 3} and BaGe{sub 3}. The variation of the alkaline-earth metal has a merely insignificant influence on the superconducting transition temperatures in the s,p-electron compounds AEGe{sub 3}.

Heavy atom disorder in the high Tsub(c) superconductor Ba2YCu3Osub(7-delta) studied by means of electron microscopy and electron diffraction

International Nuclear Information System (INIS)

Tendeloo, G. van; Okabe, T.; Zandbergen, H.W.; Amelinckx, S.

1987-01-01

It is shown that on rapid cooling of the compound Ba 2 YCu 3 Osub(7-δ) one obtains a highly disordered material in which the perovskite framework is conserved but in which barium and yttrium atoms exhibit a high degree of disorder. This leads to lattice deformations, which can be visualized in the electron microscope. The electron diffraction patterns also reveal the disorder. As-quenched specimens are no longer high Tsub(c) superconductors, but the superconducting properties can be recovered by an adequate heat treatment whereby the vacancies become ordered. (author)

Theoretical and experimental study on solid chemical reaction between BaCO3 and TiO2 in microwave field

International Nuclear Information System (INIS)

Liu Hanxing; Guo, Liling; Zou Long; Cao Minhe; Zhou Jian; Ouyang Shixi

2004-01-01

Solid-state chemical reaction mechanism for the reaction between BaCO 3 and TiO 2 in microwave field was investigated based on X-ray power diffraction (XRD) data and theory of diffusion. The compositions of the resultant after reaction under different conditions were studied by employing XRD. The quantitative analyses based on XRD data showed the reaction in microwave field was quite different from that in the conventional method. A model was proposed to explain the change of the ratio between the reactant BaCO 3 , TiO 2 and the resultant BaTiO 3 for the chemical reaction. The formation kinetic of BaTiO 3 from the BaCO 3 and TiO 2 was calculated by employing this theoretical model. The reaction rate between BaCO 3 and TiO 2 in microwave field was much higher than that in conventional method. The activation energy of the atomic diffusions in this solid chemical reaction is only 58 kJ/mol, which was only about 1/4 of 232 kJ/mol in the conventional value. The result suggests that the microwave field enhance atomic diffusion during the reaction

Quasi-atoms

International Nuclear Information System (INIS)

Armbruster, P.

1976-01-01

The concept of a quasi-atom is discussed, and several experiments are described in which molecular or quasi-atomic transitions have been observed. X-ray spectra are shown for these experiments in which heavy ion projectiles were incident on various targets and the resultant combined system behaved as a quasi-atom. This rapidly developing field has already given new insight into atomic collision phenomena. (P.J.S.)

Mass spectrometric determination of stability of gaseous BaMoO2, Ba2MoO4, Ba2MoO5, Ba2Mo2O8 molecules

International Nuclear Information System (INIS)

Kudin, L.S.; Balduchchi, Dzh.; Dzhil'i, G.; Gvido, M.

1982-01-01

During the mass spectrometric investigation of BaCrO 4 evaporation Cr + , Ba + , BaO + main ions are recorded as well as BaMoO 4 + , BaMoO 3 + , BaMoO 2 + , BaMoO + , BaMoO 4 + , Ba 2 MoO 5 + , BaMo 2 O 8 + ions - the products of ionization of three-component (Ba, Mo, M) molecules, forming as a result of substance chemical interaction with the material of an effusion cell (Mo). Heats of formation of BaMoO 2 , Ba 2 MoO 4 , Ba 2 MoO 5 and Ba 2 Mo 2 O 8 molecules which constituted - 577+-70, -1343+-115, -1464+-70, -2393+-90 k J/mol respectively are determined on the base of the analysis of curves of ionisation efficiency and of reaction heats Ba 2 MoO 5 =BaO+BaMoO 4 , ΔH 0 0 =322+-60 kJ/mol Ba 2 Mo 2 O 8 =2BaMoO 4 , ΔH 0 0 =351+-80 kJ/mol calculated with the use of third low of thermodynamics [ru

Dynamic grazing incidence fast atom diffraction during molecular beam epitaxial growth of GaAs

Energy Technology Data Exchange (ETDEWEB)

Atkinson, P., E-mail: atkinson@insp.jussieu.fr; Eddrief, M. [Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, F-75005 Paris (France); CNRS, UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, F-75005 Paris (France); Etgens, V. H. [CNRS, UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, F-75005 Paris (France); VeDeCom-Université Versailles Saint-Quentin en Yvelines, Versailles (France); Khemliche, H., E-mail: hocine.khemliche@u-psud.fr; Debiossac, M.; Mulier, M.; Lalmi, B.; Roncin, P. [ISMO UMR8214 CNRS-Université Paris-Sud, Orsay F-91400 (France); Momeni, A. [ISMO UMR8214 CNRS-Université Paris-Sud, Orsay F-91400 (France); Univ. Cergy Pontoise, F-95031 Cergy (France)

2014-07-14

A Grazing Incidence Fast Atom Diffraction (GIFAD) system has been mounted on a commercial molecular beam epitaxy chamber and used to monitor GaAs growth in real-time. In contrast to the conventionally used Reflection High Energy Electron Diffraction, all the GIFAD diffraction orders oscillate in phase, with the change in intensity related to diffuse scattering at step edges. We show that the scattered intensity integrated over the Laue circle is a robust method to monitor the periodic change in surface roughness during layer-by-layer growth, with oscillation phase and amplitude independent of incidence angle and crystal orientation. When there is a change in surface reconstruction at the start of growth, GIFAD intensity oscillations show that there is a corresponding delay in the onset of layer-by-layer growth. In addition, changes in the relative intensity of different diffraction orders have been observed during growth showing that GIFAD has the potential to provide insight into the preferential adatom attachment sites on the surface reconstruction during growth.

O vacancy formation in (Pr/Gd)BaCo2O5.5 and the role of antisite defects

KAUST Repository

Omotayo Akande, Salawu; Chroneos, Alexander; Schwingenschlö gl, Udo

2017-01-01

that O vacancy formation is significantly easier in PrBaCo2O5.5 than in GdBaCo2O5.5, the difference in formation energy being hardly modified by antisite defects. While pyramidally coordinated Co atoms are not affected, we show that the presence

Spectral interferences in atomic absorption spectrometry, (5)

International Nuclear Information System (INIS)

Daidoji, Hidehiro

1979-01-01

Spectral interferences were observed in trace element analysis of concentrated solutions by atomic absorption spectrometry. Molecular absorption and emission spectra for strontium chloride and nitrate, barium chloride and nitrate containing 12 mg/ml of metal ion in airacetylene flame were measured in the wavelength range from 200 to 700 nm. The absorption and emission spectra of SrO were centered near 364.6 nm. The absorption spectra of SrOH around 606.0, 671.0 and 682.0 nm were very strong. And, emission spectrum of BaOH in the wavelength range from 480 to 550 nm was stronger. But, the absorption of this band spectrum was very weak. In the wavelength range from 200 to 400 nm, some unknown bands of absorption were observed for strontium and barium. Absorption spectra of SrCl and BaCl were observed in the argon-hydrogen flame. Also, in the carbon tube atomizer, the absorption spectra of SrCl and BaCl were detected clearly in the wavelength range from 185 to 400 nm. (author)

Synthesis and thermoelectric properties of rare earth Yb-doped Ba8−xYbxSi30Ga16 clathrates

International Nuclear Information System (INIS)

Liu, Lihua; Li, Feng; Wei, Yuping; Chen, Ning; Bi, Shanli; Qiu, Hongmei; Cao, Guohui; Li, Yang

2014-01-01

Highlights: • Samples with the chemical formula Ba8− x Yb x Si 30 Ga 16 (x = 0, 0.5, 0.7, 1 and 1.5) were prepared. • Some Yb atoms enter the clathrate lattice to replace Ba, while other Yb atoms are oxidized as Yb 2 O 3 . • The thermal conductivity decreases with Yb-doping. • Thermoelectric figure of merit ZT significantly increased. -- Abstract: The potential thermoelectric and magnetic application of clathrate materials with rare-earth doping is the focus of much of the recent research activity in the synthetic material physics and chemistry. A series of clathrate samples with the chemical formula Ba 8−x Yb x Si 30 Ga 16 (x = 0, 0.5, 0.7, 1 and 1.5) were prepared by combining arc melting, ball milling and spark plasma sintering (SPS) techniques. X-ray diffraction and scanning electronic microscopy combined with energy-dispersive X-ray spectroscopy (EDS) analysis showed the dominant phase to be the type-I clathrate. Whereas, X-ray structural refinement and EDS analysis indicated that some Yb atoms enter the clathrate lattice to replace Ba at 2a sites, while other Yb atoms are oxidized as Yb 2 O 3 precipitated around grain boundaries. The solid solubility of Yb into clathrate lattice yielded x ∼ 0.3. Comparative analysis between Yb-doped and Yb-free clathrates showed that the thermal conductivity decreases with Yb-doping. Consequently, thermoelectric figure of merit ZT significantly increased

Quantum treatment of the capture of an atom by a fast nucleus incident on a molecule

International Nuclear Information System (INIS)

Shakeshaft, R.; Spruch, L.

1980-01-01

The classical double-scattering model of Thomas for the capture of electrons from atoms by fast ions yields a cross section sigma which dominates over the single scattering contribution for sufficiently fast ions. The magnitude of the classical double-scattering sigma differs, however, from its quantum-mechanical (second-Born) analog by an order of magnitude. Further, a ''fast ion'' means an ion of some MeV, and at those energies the cross sections are very low. On the other hand, as noted by Bates, Cook, and Smith, the double-scattering cross section for the capture of atoms from molecules by fast ions dominates over the single-scattering contribution for incident ions of very much lower energy; roughly, one must have the velocity of the incident projectile much larger than a characteristic internal velocity of the particles in the target. It follows that we are in the asymptotic domain not at about 10 MeV but at about 100 eV. For the reaction H + +CH 4 → H 2 + +CH 3 with incident proton energies of 70 to 150 eV, the peak in the angular distribution as determined experimentally is at almost precisely the value predicted by the classical model, but the theoretical total cross section is about 30 times too large. Using a quantum version of the classical model, which involves the same kinematics and therefore preserves the agreement with the angular distribution, we obtain somewhat better agreement with the experimental total cross section, by a factor of about 5. In the center-of-mass frame, for sufficiently high incident energy, the first of the two scatterings involves the scattering of H + by H through an angle of very close to 90 0 , and it follows that the nuclei of the emergent H 2 + ion will almost all be in the singlet state. We have also calculated the cross section for the reaction D + +CH 4 → (HD) + +CH 3

Leukemia incidence in the atomic bomb survivor Life Span Study, 1950 - 87

International Nuclear Information System (INIS)

Preston, D.L.; Mabuchi, K.; Kusumi, S.; Izumi, S.

1992-01-01

The Radiation Effects Research Foundation (RERF) is currently preparing a series of reports on cancer incidence in the Life Span Study (LSS) cohort of atomic bomb survivors for the period from 1950 to 1987. One of these reports will present analyses of the data on the risk of hematopoietic cancers including leukemia, malignant lymphoma, and multiple myeloma. These analyses add an additional 11 years of follow-up to the previous comprehensive analysis of the LSS leukemia data. In this presentation, these data are presented and the methods being used modeling the leukemia risks are outlined. An analysis of the leukemia data pooled over subtypes will be used to illustrate these methods. It is shown that the data suggest a non-linear, concave upward dose response and that the temporal pattern of the radiation-induced excess absolute risks (EARs) depends on age-at-exposure and sex. There is no evidence of city differences in the EAR in this pooled analysis. The results suggest that the EARs for the youngest survivors were initially much higher and have declined more rapidly than those for older survivors. The same general pattern is seen both sexes, but the initial peak incidence is somewhat lower and the rate of decline less rapid for women than for men. (author)

Ordered perovskites with cationic vacancies. 7. Structural investigations on Ba/sub 2/Zrsub(3/4)vacantsub(1/4)SbO/sub 6/

Energy Technology Data Exchange (ETDEWEB)

Treiber, U; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-11-01

The ochre coloured Ba/sub 2/Zrsub(3/4)vacantsub(1/4)SbO/sub 6/ belongs to the group of oxygen perovskites with an ordered distribution of the vacancies. It crystallizes tetragonal (a = 11.68/sub 5/ A; c = 16.60/sub 6/ A) with 16 formula units in the cell: Ba/sub 32/Zr/sub 12/vacant/sub 4/Sb/sub 16/O/sub 96/. For the space group P 4/mmm intensity calculations on powder data gave a refined, intensity related R' value of 4.8%. In the structure the Zr and Ba atoms are ordered (1:1 order); the four cationic vacancies are located in a face centered arrangement in the zirconium sublattice. The Ba atoms are displaced by approximately 0.20 A in direction of the neighbouring vacancy, while the other cations maintain their ideal positions.

Phase equilibria, crystal chemistry, electronic structure and physical properties of Ag-Ba-Ge clathrates

Energy Technology Data Exchange (ETDEWEB)

Zeiringer, I.; Chen Mingxing [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Bednar, I.; Royanian, E.; Bauer, E. [Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Wien (Austria); Podloucky, R.; Grytsiv, A. [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Rogl, P., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Effenberger, H. [Institute of Mineralogy and Crystallography, University of Vienna, A-1090 Wien (Austria)

2011-04-15

In the Ag-Ba-Ge system the clathrate type-{Iota} solid solution, Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y}, extends at 800 deg. C from binary Ba{sub 8}Ge{sub 43{open_square}3} ({open_square} is a vacancy) to Ba{sub 8}Ag{sub 5.3}Ge{sub 40.7}. For the clathrate phase (1 {<=} x {<=} 5.3) the cubic space group Pm3-bar n was established by X-ray powder diffraction and confirmed by X-ray single-crystal analyses of the samples Ba{sub 8}Ag{sub 2.3}Ge{sub 41.9{open_square}1.8} and Ba{sub 8}Ag{sub 4.4}Ge{sub 41.3{open_square}0.3}. Increasing the concentration of Ag causes the lattice parameters of the solid solution to increase linearly from a value of a = 1.0656 (x = 0, y = 3) to a = 1.0842 (x = 4.8, y = 0) nm. Site preference determination using X-ray refinement reveals that Ag atoms preferentially occupy the 6d site randomly mixed with Ge and vacancies, which become filled in the compound Ba{sub 8}Ag{sub 4.8}Ge{sub 41.2} when the Ag content increases. At 600 {sup o}C the phase region of the clathrate solution Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} becomes separated from the Ba-Ge boundary and extends from 6.6 to 9.8 at.% Ag. The compound Ba{sub 6}Ge{sub 25} (clathrate type-{Iota}X) dissolves at 800 {sup o}C a maximum of 1.5 at.% Ag. The homogeneity regions of the two ternary compounds BaAg{sub 2-x}Ge{sub 2+x} (ThCr{sub 2}Si{sub 2}-type, 0.2 {<=} x {<=} 0.7) and Ba(Ag{sub 1-x}Ge{sub x}){sub 2} (AlB{sub 2}-type, 0.65 {<=} x {<=} 0.75) were established at 800 deg. C. Studies of transport properties for the series of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} compounds evidenced that electrons are the predominant charge carriers with the Fermi energy close to a gap. Its position can be fine-tuned by the substitution of Ge by Ag atoms and by mechanical processing of the starting material, Ba{sub 8}Ge{sub 43}. The proximity of the electronic structure at Fermi energy of Ba{sub 8}Ag{sub x}Ge{sub 46-x-y{open_square}y} to a gap is also corroborated by density

First-principles calculations on the four phases of BaTiO3.

Science.gov (United States)

Evarestov, Robert A; Bandura, Andrei V

2012-04-30

The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques. It is concluded that the hybrid PBE0 [J. P. Perdew, K. Burke, M. Ernzerhof, J. Chem. Phys. 1996, 105, 9982.] functional is able to predict correctly the structural stability and phonon properties both for cubic and ferroelectric phases of BaTiO(3). The comparative phonon symmetry analysis in BaTiO(3) four phases has been made basing on the site symmetry and irreducible representation indexes for the first time. Copyright © 2012 Wiley Periodicals, Inc.

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Prakash, Jai [Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 (United States); Mesbah, Adel [Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 (United States); ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Beard, Jessica [Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 (United States); Lebègue, Sébastien [Laboratoire de Cristallographie, Résonance Magnétique et Modélisations (CRM2, UMR CNRS 7036), Institut Jean Barriol, Université de Lorraine, BP 239, Boulevard des Aiguillettes, 54506 Vandoeuvre-lès-Nancy (France); Malliakas, Christos D. [Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 (United States); Ibers, James A., E-mail: ibers@chem.northwestern.edu [Department of Chemistry, Northwestern University, Evanston, IL 60208-3113 (United States)

2015-11-15

The compound Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} has been synthesized by solid-state methods at 1173 K. Its crystal structure features one-dimensional chains of {sup 1}{sub ∞}[Th(Se){sub 3}(Se{sub 2}){sub 2}{sup 6−}] separated by Ba{sup 2+} cations. Each Th atom in these chains is coordinated to two Se–Se single-bonded pairs and four Se atoms to give rise to a pseudooctahedral geometry around Th. The Th–Se distances are consistent with Th{sup 4+} and hence charge balance of Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} is achieved as 3×Ba{sup 2+}, 1×Th{sup 4+}, 3×Se{sup 2−}, and 2×Se{sub 2}{sup 2−}. From optical measurements the band gap of Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} is 1.96(2) eV. DFT calculations indicate that the compound is a semiconductor. - Graphical abstract: Local coordination environment of Th atoms in the Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} structure. - Highlights: • Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} has been synthesized by solid-state methods at 1173 K. • The structure features chains of {sup 1}{sub ∞}[Th(Se){sub 3}(Se{sub 2}){sub 2}{sup 6−}] separated by Ba{sup 2+} cations. • Ba{sub 3}ThSe{sub 3}(Se{sub 2}){sub 2} is a semiconductor with a band gap of 1.96(2) eV.

Characterization of the insulator barrier and the superconducting transition temperature in GdBa2Cu3O7−δ/BaTiO3 bilayers for application in tunnel junctions

International Nuclear Information System (INIS)

Navarro, H.; Sirena, M.; Haberkorn, N.; Yang, Ilkyu; Kim, Jeehoon

2015-01-01

The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO 3 tunnel barrier deposited on a 16 nm thick GdBa 2 Cu 3 O 7−δ thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO 3 barrier thickness between 1.6 and 4 nm. The BaTiO 3 layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa 2 Cu 3 O 7−δ electrode is totally covered by a BaTiO 3 thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO 3 top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO 3 thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa 2 Cu 3 O 7−δ . The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO 3 barrier)

Photoluminescence properties of BaMoO4 amorphous thin films

International Nuclear Information System (INIS)

Marques, Ana Paula Azevedo; Melo, Dulce M.A. de; Longo, Elson; Paskocimas, Carlos A.; Pizani, Paulo S.; Leite, Edson R.

2005-01-01

BaMoO 4 amorphous and crystalline thin films were prepared from polymeric precursors. The BaMoO 4 was deposited onto Si wafers by means of the spinning technique. The structure and optical properties of the resulting films were characterized by FTIR reflectance spectra, X-ray diffraction (XRD), atomic force microscopy (AFM) and optical reflectance. The bond Mo-O present in BaMoO 4 was confirmed by FTIR reflectance spectra. XRD characterization showed that thin films heat-treated at 600 and 200 deg. C presented the scheelite-type crystalline phase and amorphous, respectively. AFM analyses showed a considerable variation in surface morphology by comparing samples heat-treated at 200 and 600 deg. C. The reflectivity spectra showed two bands, positioned at 3.38 and 4.37 eV that were attributed to the excitonic state of Ba 2+ and electronic transitions within MoO 2- 4 , respectively. The optical band gaps of BaMoO 4 were 3.38 and 2.19 eV, for crystalline (600 deg. C/2 h) and amorphous (200 deg. C/8 h) films, respectively. The room-temperature luminescence spectra revealed an intense single-emission band in the visible region. The PL intensity of these materials was increased upon heat-treatment. The excellent optical properties observed for BaMoO 4 amorphous thin films suggested that this material is a highly promising candidate for photoluminescent applications

Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

International Nuclear Information System (INIS)

Wang, S.F.; Li, Q.; Zu, X.T.; Xiang, X.; Liu, W.; Li, S.

2016-01-01

(Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

From Ba3Ta5O14N to LaBa2Ta5O13N2: Decreasing the optical band gap of a photocatalyst

International Nuclear Information System (INIS)

Anke, B.; Bredow, T.; Pilarski, M.; Wark, M.; Lerch, M.

2017-01-01

Yellow LaBa 2 Ta 5 O 13 N 2 was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba 3 Ta 5 O 14 N and mixed-valence Ba 3 Ta V 4 Ta IV O 15 . The electronic structure of LaBa 2 Ta 5 O 13 N 2 was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba 3 Ta 5 O 14 N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba 3 Ta 5 O 14 N revealing significantly higher activity for LaBa 2 Ta 5 O 13 N 2 under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa 2 Ta 5 O 13 N 2 with the results of the Rietveld refinements. Inset: Unit cell of LaBa 2 Ta 5 O 13 N 2 and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa 2 Ta 5 O 13 N 2 . • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H 2 evolution rate compared to prior tested Ba 3 Ta 5 O 14 N.

Interaction of complex atoms with radiation

International Nuclear Information System (INIS)

Amus'ya, M.Ya.

1984-01-01

Different manifestations of multielectron atomic structure under photoionization are discussed. Collectivization of external electron shells essential both in production cross section and in angular distribution as well as in photoelectron polarization are noted. In a wide range of quantum energies (of the order of ionization potential) an incident electron scattering on the atom irradiates quite differently than on the potential. It polarizes atoms mainly dipolarly, and virtually excited atom emits ''bremsstrahlung'' quantum. With energy growth of the incident electron at small momentum transferred to it by the atom the role of the second mechanism turns to be determinant

First-principles study of the alkali earth metal atoms adsorption on graphene

International Nuclear Information System (INIS)

Sun, Minglei; Tang, Wencheng; Ren, Qingqiang; Wang, Sake; JinYu; Du, Yanhui; Zhang, Yajun

2015-01-01

Graphical abstract: - Highlights: • The adsorption of Be and Mg adatoms on graphene is physisorption. • Ca, Sr, and Ba adatoms bond ionically to graphene and the most stable adsorption site for them is hollow site. • The zero band gap semiconductor graphene becomes metallic and magnetic after the adsorption of Ca, Sr, and Ba adatoms. - Abstract: Geometries, electronic structures, and magnetic properties for alkali earth metal atoms absorbed graphene have been studied by first-principle calculations. For Be and Mg atoms, the interactions between the adatom and graphene are weak van der Waals interactions. In comparison, Ca, Sr and Ba atoms adsorption on graphene exhibits strong ionic bonding with graphene. We found that these atoms bond to graphene at the hollow site with a significant binding energy and large electron transfer. It is intriguing that these adatoms may induce important changes in both the electronic and magnetic properties of graphene. Semimetal graphene becomes metallic and magnetic due to n-type doping. Detailed analysis shows that the s orbitals of these adatoms should be responsible for the arising of the magnetic moment. We believe that our results are suitable for experimental exploration and useful for graphene-based nanoelectronic and data storage.

First-principles study of the alkali earth metal atoms adsorption on graphene

Energy Technology Data Exchange (ETDEWEB)

Sun, Minglei [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Tang, Wencheng, E-mail: 101000185@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Ren, Qingqiang [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan (China); Wang, Sake [Department of Physics, Southeast University, Nanjing 210096, Jiangsu (China); JinYu [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, Jiangsu (China); Du, Yanhui [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Zhang, Yajun [Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, Zhejiang (China)

2015-11-30

Graphical abstract: - Highlights: • The adsorption of Be and Mg adatoms on graphene is physisorption. • Ca, Sr, and Ba adatoms bond ionically to graphene and the most stable adsorption site for them is hollow site. • The zero band gap semiconductor graphene becomes metallic and magnetic after the adsorption of Ca, Sr, and Ba adatoms. - Abstract: Geometries, electronic structures, and magnetic properties for alkali earth metal atoms absorbed graphene have been studied by first-principle calculations. For Be and Mg atoms, the interactions between the adatom and graphene are weak van der Waals interactions. In comparison, Ca, Sr and Ba atoms adsorption on graphene exhibits strong ionic bonding with graphene. We found that these atoms bond to graphene at the hollow site with a significant binding energy and large electron transfer. It is intriguing that these adatoms may induce important changes in both the electronic and magnetic properties of graphene. Semimetal graphene becomes metallic and magnetic due to n-type doping. Detailed analysis shows that the s orbitals of these adatoms should be responsible for the arising of the magnetic moment. We believe that our results are suitable for experimental exploration and useful for graphene-based nanoelectronic and data storage.

Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

Energy Technology Data Exchange (ETDEWEB)

Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

2016-12-01

(Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

Refinement of crystal structures of CaHCl, SrHCl, BaHCl, BaHBr, and BaHI

International Nuclear Information System (INIS)

Beck, H.P.; Limmer, A.

1983-01-01

The structures of CaHCl, SrHCl, BaHBr, BaHCl, and BaHI have been refined using single crystal data. The comparison of the parameters with the corresponding data of isotypic fluorohalide compounds gives a valuable insight into the bonding interactions in this structure type. (author)

Refinement of crystal structures of CaHCl, SrHCl, BaHCl, BaHBr, and BaHI

Energy Technology Data Exchange (ETDEWEB)

Beck, H.P.; Limmer, A. (Erlangen-Nuernberg Univ., Erlangen (Germany, F.R.). Inst. fuer Anorganische Chemie)

1983-07-01

The structures of CaHCl, SrHCl, BaHBr, BaHCl, and BaHI have been refined using single crystal data. The comparison of the parameters with the corresponding data of isotypic fluorohalide compounds gives a valuable insight into the bonding interactions in this structure type.

The double-well oscillating potential of oxygen atoms in perovskite system Ba(K)BiO sub 3 : EXAFS - analysis results

CERN Document Server

Menushenkov, A P; Konarev, P V; Meshkov, A A; Benazeth, S; Purans, J

2000-01-01

Temperature-dependent X-ray absorption investigations were made on the Bi L sub 3 -edge in Ba sub 1 sub - sub x K sub x BiO sub 3 with x=0.0, 0.4 and 0.5. For the superconducting samples (x=0.4 and 0.5) it has been found that the local structure differs from the ideal cubic in contrast to the neutron and X-ray diffraction data. The provided analysis of the EXAFS spectra indicates that the oxygen atoms move in double-well potential produced by the existence of two non-equivalent octahedral types of the oxygen environment of bismuth. The vibrations in such a potential lead to modulations of the Bi-O lengths with low frequency which is determined by the soft oxygen octahedron rotation mode frequency. This induces strong electron-phonon interaction and may be the reason for relatively high-temperature transition (T sub c approx 30 K) to the superconducting state.

Composition changes in sputter deposition of Y-Ba-Cu-O films

International Nuclear Information System (INIS)

Hoshi, Y.; Naoe, M.

1989-01-01

The authors discuss the mechanism of the composition change in sputter deposition of Y-BA-Cu-O film from YBa 2 Cu 3 O 7-chi target investigated by means of a rf planar magnetron sputtering apparatus. Film composition changes significantly with not only substrate temperature Ts and sputtering gas pressure, but also substrate position. Lack of Cu and Ba content is significant in the film deposited at the substrate position just above the erosion area of the sputtering target. Suppression of bombardment of the substrate surface by negative ions emitted from the target and substrate is effective in increasing Cu and Ba content in the film. These results indicate not only that the sticking probability of the sputtered particles changes with Ts and incident particle energy, but also that high energy particle bombardment of the substrate surface plays an important role in the change of the film composition

Observation of weakly adsorbed oxygen on Y5Ba6Cu11Oy

International Nuclear Information System (INIS)

Kao, Sendjaja; Ng, K.Y.S.

1992-01-01

In the Y-Ba-Cu-O compound, several investigators have observed superconductivity-like phenomena at higher temperatures, some even reaching zero resistance at 250 K. Huang et al. reported an observation of sharp resistivity drops, at least four orders of magnitude at ca. 230 K, in one annealed sample of Eu 1 Ba 2 Cu 3 O 6+x . But the resistance drop disappeared after thermal cycling, although the correlated magnetic anomalies observed in their magnetic measurements persisted for many thermal cycles. Recently, Chen et al reported that the superconductivity-like transition at a temperature above 200 K in their mixed-phase YBaCuO persisted for 29 thermal cycles. The samples were treated by a low-temperature (50-70C) oxygenation process and enclosed in oxygen environment during electrical and magnetic measurements. They also found that this higher-temperature transition could not survive thermal cycling when the sample was in helium atmosphere. The role oxygen plays in their observations is not clear, but they speculated that weakly bonded oxygen atom/atoms are responsible for the high-temperature phase. This observation of T c > 200 K in oxygen environment is recently confirmed by Schonberger et al. in highly oriented multiphase Y-Ba-Cu-O thin film. Here, the authors observed, for the first time, adsorption of weakly bonded oxygen at low temperature (≤250C) by a Y 5 Ba 6 Cu 11 O y sample, using thermogravimetric analysis. The resulting oxygen enriched phase in the surface layers may be attributed to the observation of a superconductivity-like transition at above 200 K

High resolution imaging of La0.5Ba0.5MnO-LaMnO superlattice

International Nuclear Information System (INIS)

Shapoval, O.; Belenchuk, A.; Verbeeck, J.; Moshnyaga, V.

2013-01-01

Full text: Artificial low dimensional systems of tailored on atomic layer level manganites is a very promising class of materials for future spintronic applications. The high resolution transmission electron microscopy imaging provides a powerful approach to extract structural, chemical and functional information on atomic level in a real space. Recently, we have reported on the Metalorganic Aerosol Deposition synthesis and properties of superlattices (SL) composed from (LaMnO 3 ) n and (La 0.5 Ba 0.5 MnO 3 ) 2n with n=1-2 of perovskite monolayers. The functional properties of digitally synthesized SL are similar to the optimal doped 'bulk' thin film material. The similarities between their properties can be interpreted in frame of the many-body interactions responsible for the properties of the single-layer and bilayer manganites. This work presents the systematic studies of atomically resolved structure of (LaMnO 3 ) n /(La 0.5 Ba 0.5 MnO 3 ) 2n , n=1 by high angle annular dark field scanning transmission electron microscopy (HAADF STEM) and electron energy loss spectroscopy (EELS). The combination of atomic-resolution Z-contrast and EELS represents a powerful method to link the atomic and electronic structure of solids with macroscopic properties. All images were obtained along orientations and low magnification one shows an overview of a whole 40-nm thick structure, whereas magnified high-resolution images demonstrate an epitaxial growth of LBMO/LMO superlattice on SrTiO 3 substrate. The SL-substrate interface is coherent and free of defects, but reveals a high level of La diffusion into SrTiO 3 . EELS together with STEM are used for probing of a local chemical composition as well as a local electronic state of transition metals and oxygen. Small modulations in the La and Ba EELS signals, which are corresponded to the LBMO and LMO layers, can be observed. The observed features at the substrate interface as well as the SL periodicity in EELS profiles are

Phase equilibria in the BaUO3-BaZrO3-BaMoO3 system

International Nuclear Information System (INIS)

Kurosaki, Ken; Yamanaka, Shinsuke; Matsuda, Tetsushi; Uno, Masayoshi; Yamamoto, Kazuya; Namekawa, Takashi

2002-01-01

The phase equilibria in the pseudo-ternary BaUO 3 -BaZrO 3 -BaMoO 3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a Chem Sage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO 3 was scarcely included in the gray oxide phase. (author)

Ba-DOPED ZnO MATERIALS: A DFT SIMULATION TO INVESTIGATE THE DOPING EFFECT ON FERROELECTRICITY

Directory of Open Access Journals (Sweden)

Luis H. da S. Lacerda

2016-04-01

Full Text Available ZnO is a semiconductor material largely employed in the development of several electronic and optical devices due to its unique electronic, optical, piezo-, ferroelectric and structural properties. This study evaluates the properties of Ba-doped wurtzite-ZnO using quantum mechanical simulations based on the Density Functional Theory (DFT allied to hybrid functional B3LYP. The Ba-doping caused increase in lattice parameters and slight distortions at the unit cell angle in a wurtzite structure. In addition, the doping process presented decrease in the band-gap (Eg at low percentages suggesting band-gap engineering. For low doping amounts, the wavelength characteristic was observed in the visible range; whereas, for middle and high doping amounts, the wavelength belongs to the Ultraviolet range. The Ba atoms also influence the ferroelectric property, which is improved linearly with the doping amount, except for doping at 100% or wurtzite-BaO. The ferroelectric results indicate the ZnO:Ba is an strong option to replace perovskite materials in ferroelectric and flash-type memory devices.

Nonresonant absorption of one photon by one atom and resonant absorption of two photons by two atoms

International Nuclear Information System (INIS)

Mizushima, Masataka

1990-01-01

When a radiation field of frequency ω 1 interacts with atoms, etch of which has a transition frequency ω ba =(E b -E a )/h, with ω 1 -ω ba =Δ≠0, nonresonant absorption can take place with probability P 1 inversely proportional to Δ 2 (a pressure broadening). When another radiation field of frequency ω 2 , such that ω 1 +ω 2 =2ω ba, interacts simultaneously with the gas a resonant two-photon absorption can take place in addition to the nonresonant absorption. The probability of this two-photon absorption process, P 2 , is found to be inversely proportional to Δ 4 . If Ω=| | is the Rabi frequency of the transition, it is found that P 2 /(P 1 (Δ)+P 1 (-Δ)) is given by 12 {Ω(-Δ)Ω(-Δ)} 2 / {Δ 2 (Ω(-Δ) 2 + Ω(Δ) 2 )}. (author)

Effects of Ba doping on physical properties of La-Ca-Mn-O thin films

CERN Document Server

Hong, N H; Sakai, J; Iwasaki, H

2003-01-01

Transport and magnetic properties of La-Ba-Ca-Mn-O thin films fabricated by the pulsed laser deposition technique had been investigated systematically to see the effects of substitution of the small atom Ca by Ba which is much bigger. The induced insulator-to-metal (IM) transition was obtained not only in compositions near 0.5 and 0.18 which are boundaries between metallic and insulating phases but also in the heavily doped region. In the region of x > 0.5, the Ba doping causes an anomalous response of the system to the magnetic field and a positive magnetoresistance was observed. Besides, our results concerning the vicinity of 0.5 imply the existence of phase separation. As for x < 0.5, the doping enhances remarkably the paramagnetism-ferromagnetism transition and the IM transition temperatures.

Patterns of remission, continuation and incidence of broadly defined eating disorders during early pregnancy in the Norwegian Mother and Child Cohort Study (MoBa).

Science.gov (United States)

Bulik, Cynthia M; Von Holle, Ann; Hamer, Robert; Knoph Berg, Cecilie; Torgersen, Leila; Magnus, Per; Stoltenberg, Camilla; Siega-Riz, Anna Maria; Sullivan, Patrick; Reichborn-Kjennerud, Ted

2007-08-01

We explored the course of broadly defined eating disorders during pregnancy in the Norwegian Mother and Child Cohort Study (MoBa) at the Norwegian Institute of Public Health. A total of 41,157 pregnant women, enrolled at approximately 18 weeks' gestation, had valid data from the Norwegian Medical Birth Registry. We collected questionnaire-based diagnostic information on broadly defined anorexia nervosa (AN), and bulimia nervosa (BN), and eating disorders not otherwise specified (EDNOS). EDNOS subtypes included binge eating disorder (BED) and recurrent self-induced purging in the absence of binge eating (EDNOS-P). We explored rates of remission, continuation and incidence of BN, BED and EDNOS-P during pregnancy. Prepregnancy prevalence estimates were 0.1% for AN, 0.7% for BN, 3.5% for BED and 0.1% for EDNOS-P. During early pregnancy, estimates were 0.2% (BN), 4.8% (BED) and 0.1% (EDNOS-P). Proportions of individuals remitting during pregnancy were 78% (EDNOS-P), 40% (BN purging), 39% (BED), 34% (BN any type) and 29% (BN non-purging type). Additional individuals with BN achieved partial remission. Incident BN and EDNOS-P during pregnancy were rare. For BED, the incidence rate was 1.1 per 1000 person-weeks, equating to 711 new cases of BED during pregnancy. Incident BED was associated with indices of lower socio-economic status. Pregnancy appears to be a catalyst for remission of some eating disorders but also a vulnerability window for the new onset of broadly defined BED, especially in economically disadvantaged individuals. Vigilance by health-care professionals for continuation and emergence of eating disorders in pregnancy is warranted.

First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com; Wei, Zhan-Long; Xiao, Cheng

2017-04-15

The crystal structure, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} become smaller and Eu–N bond length shortens as Eu concentration increases. The band structure of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eu concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. Under the coupling effect between Eu and Ba, Ba in BaSi{sub 2}O{sub 2}N{sub 2} exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu{sup 2+} doping range. - Graphical abstract: The structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT and its absorption mechanism is analysed. Results show that absorption peak α is from the host lattice absorption. The absorption peaks β, γ and δ are from Eu 4f to Eu 5d and Ba 6s 5d states. The absorption is attributed to the coupling effect of Eu and Ba atom. - Highlights: • The crystal, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT. • The lattice parameters of primitive cells reduces and Eu–N bond length shortens as Eu{sup 2+} increases. • The energy gap from Eu 5d state to Eu 4f state

K$_{-}$ and K$_{-}$ polarizability from kaonic atoms

CERN Document Server

Backenstoss, Gerhard; Bergström, I; Bunaciu, T; Egger, J; Hagelberg, R; Hultberg, S; Koch, H; Lynen, Y; Ritter, H G; Schwitter, A; Tauscher, L

1973-01-01

The K/sup -/ mass was determined from kaonic atomic X-rays from Au and Ba to be 493.691+or-0.040 MeV. An upper limit for the polarizability of the K/sup -/ was found to be 0.020 fm/sup 3/ at 90% confidence. (18 refs).

Defect chemistry of ''BaCuO2''. Pt. 2. Transport properties and nature of defects

International Nuclear Information System (INIS)

Chiodelli, G.; Consiglio Nazionale delle Ricerche, Pavia; Anselmi-Tamburini, U.; Consiglio Nazionale delle Ricerche, Pavia; Arimondi, M.; Consiglio Nazionale delle Ricerche, Pavia; Spinolo, G.; Consiglio Nazionale delle Ricerche, Pavia; Flor, G.; Consiglio Nazionale delle Ricerche, Pavia

1995-01-01

The charge transport properties of ''BaCuO 2 '' with 88:90 (Ba:Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions. The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium. Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites (orig.)

Quasi-2D silicon structures based on ultrathin Me2Si (Me = Mg, Ca, Sr, Ba) films

Science.gov (United States)

Migas, D. B.; Bogorodz, V. O.; Filonov, A. B.; Borisenko, V. E.; Skorodumova, N. V.

2018-04-01

By means of ab initio calculations with hybrid functionals we show a possibility for quasi-2D silicon structures originated from semiconducting Mg2Si, Ca2Si, Sr2Si and Ba2Si silicides to exist. Such a 2D structure is similar to the one of transition metal chalcogenides where silicon atoms form a layer in between of metal atoms aligned in surface layers. These metal surface atoms act as pseudo passivation species stabilizing crystal structure and providing semiconducting properties. Considered 2D Mg2Si, Ca2Si, Sr2Si and Ba2Si have band gaps of 1.14 eV, 0.69 eV, 0.33 eV and 0.19 eV, respectively, while the former one is also characterized by a direct transition with appreciable oscillator strength. Electronic states of the surface atoms are found to suppress an influence of the quantum confinement on the band gaps. Additionally, we report Sr2Si bulk in the cubic structure to have a direct band gap of 0.85 eV as well as sizable oscillator strength of the first direct transition.

Synthesis and first-principle calculations of the structural and electronic properties of Ge-substituted type-VIII Ba{sub 8}Ga{sub 16}Sn{sub 30} clathrate

Energy Technology Data Exchange (ETDEWEB)

Shen, Lanxian [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China); Li, Decong [College of Optoelectronic Engineering, Yunnan Open University, Kunming 650500 (China); Liu, Hongxia; Liu, Zuming [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China); Deng, Shukang, E-mail: skdeng@126.com [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Provincial Renewable Energy Engineering Key Lab, Solar Energy Research Institution, Yunnan Normal University, Kunming 650500 (China)

2016-12-01

In this study, the structural and electronic structural properties of Ba{sub 8}Ga{sub 16}Sn{sub 30−x}Ge{sub x} (0≤x≤30) are determined by the first-principle method on the basis of density functional theory. Consistent with experimental findings, calculated results reveal that Ge atoms preferentially occupy the 2a and 24g sites in these compounds. As the content of Ge in Ge-substituted clathrate is increased, the lattice parameter is decreased, and the structural stability is enhanced. The bandgaps of the compound at 1≤x≤10 are smaller than those of Ba{sub 8}Ga{sub 16}Sn{sub 30}. By contrast, the bandgaps of the compound at x>10 are larger than those of Ba{sub 8}Ga{sub 16}Sn{sub 30}. The substitution of Ge for Sn affects p-type conductivity but not n-type conductivity. As Ge content increases, the whole conduction band moves to the direction of high energy, and the density of states of valence-band top decreases. The calculated potential energy versus displacement of Ba indicates that the vibration energy of this atom increases as cage size decreases. Because Ge substitution also affects clathrate structural symmetry, the distance of Ba atom deviation from the center of the cage initially increases and subsequently decreases as the Ge content increases.

Current trend of malignant neoplasms among atomic bomb survivors

International Nuclear Information System (INIS)

Hamada, Tadao

1984-01-01

A survey was made on 7,589 admitted patients and 1,965 autopsy cases. The overall incidence of malignant neoplasms tended to decrease in the group exposed to atomic bomb within 2 km in autopsy cases and to increase in admitted patients. The incidence of pulmonary cancer tended to increase in both autopsy cases and admitted patients. The incidence of gastric cancer tended to increase up to 1975, and thereafter tended to decrease. The incidence of liver cancer tended to increase in both autopsy cases and admitted patients, which was marked in males. The incidence of leukemia was high in the group exposed to atomic bomb within 2 km in autopsy cases, and in the group within 1 km and the group which entered the city after the explosion in admitted patients. The incidence of malignant lymphoma tended to decrease, and the incidence of carcinoma of the colon tended to gradually increase in both autopsy cases and admitted patients. The incidence of multiple carcinomas tended to increase in both atomic bomb exposed group and non-exposed group, being higher in atomic bomb group than in non-exposed group. The incidence of breast cancer became constant since 1970. The incidence of carcinoma of the thyroid gland tended to decrease, although it was high in the group exposed near the explosion. (Namekawa, K.)

Characterization of the insulator barrier and the superconducting transition temperature in GdBa{sub 2}Cu{sub 3}O{sub 7−δ}/BaTiO{sub 3} bilayers for application in tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Navarro, H., E-mail: henrynavarro@cab.cnea.gov.ar; Sirena, M.; Haberkorn, N. [Instituto Balseiro, Universidad Nacional de Cuyo and CNEA, 8400 Bariloche (Argentina); Centro Atómico Bariloche, Comisión Nacional de Energía Atómica. Av. Bustillo 9500, 8400 San Carlos de Bariloche (Argentina); Yang, Ilkyu [Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); Kim, Jeehoon [Department of Physics, Pohang University of Science and Technology, Pohang (Korea, Republic of); CALDES, Institute for Basic Science, Pohang (Korea, Republic of)

2015-07-28

The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO{sub 3} tunnel barrier deposited on a 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO{sub 3} barrier thickness between 1.6 and 4 nm. The BaTiO{sub 3} layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the applied voltage). The GdBa{sub 2}Cu{sub 3}O{sub 7−δ} electrode is totally covered by a BaTiO{sub 3} thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO{sub 3} top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO{sub 3} thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa{sub 2}Cu{sub 3}O{sub 7−δ}. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO{sub 3} barrier)

Thyroid disorders in atomic bomb survivors

International Nuclear Information System (INIS)

Tanaka, Yoshikiyo; Inoue, Keisuke; Sugihara, Toru; Oshima, Tetuya; Matsueda, Kazuhiro

1984-01-01

There was no difference in blood levels of thyroid stimulating hormones among atomic bomb survivors having normal thyroid function, irrespective of the exposure distance from the explosion. Of 336 atomic bomb survivors admitted to the hospital for health examinations, hyperthyroidism was seen in one patient, hypothyroidism in four, malignant struma in three, and benign tumor in one. The incidence of struma associated with positive antithyroidglobulin antibody tended to be high in atomic bomb survivors living within 1.0 km from the explosion. The overall study in patients visiting the department of internal medicine, in addition to the 336 survivors, revealed that the incidence of thyroid disorders, especially hypothyroidism, was high in survivors directly exposed to atomic bomb. (Namekawa, K.)

Density functional study of NO adsorption on undefected and oxygen defective Au–BaO(1 0 0) surfaces

Energy Technology Data Exchange (ETDEWEB)

Añez, Rafael, E-mail: ranez@ivic.gob.ve [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado, 21827 Caracas (Venezuela, Bolivarian Republic of); Sierraalta, Aníbal; Bastardo, Anelisse [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado, 21827 Caracas (Venezuela, Bolivarian Republic of); Coll, David [Laboratorio de Físico Química Teórica de Materiales, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado, 21827 Caracas (Venezuela, Bolivarian Republic of); Garcia, Belkis [Instituto Universitario de Tecnología de Valencia IUTVAL, Valencia, Edo. Carabobo (Venezuela, Bolivarian Republic of)

2014-07-01

A periodic density functional approach has been used in order to explore the interaction of NO with undoped and Au doped BaO(1 0 0) surface. Due to oxygen vacancies increase the interaction between the doping metal and the surface, F{sub S} and F{sub S}{sup +} vacancies were studied and compared with the results obtained on the undefected doped BaO(1 0 0). Our results indicate that the high basicity of the BaO surface, besides the electron density changes produced by the oxygen vacancies, modify considerably how the Au atom interacts with the surface increasing the ionic character of the interaction. F{sub S} vacancy shows to be a promise center to activate de NO bond on the BaO(1 0 0) surface.

Gastos em saúde e incidência de benefício no município de Senhor do Bonfim (BA em 2003 Publics expenditures and benefit incidence in Senhor do Bonfim, city of the state of Bahia, in 2003

Directory of Open Access Journals (Sweden)

Erika Aragão

2007-08-01

Full Text Available O objetivo deste artigo é analisar a desigualdade no acesso e utilização dos serviços de saúde no município de Senhor do Bonfim (BA. O método utilizado é o "benefit incidence", ou incidência de benefício, que permite identificar quais os grupos sociais que se beneficiam dos gastos do Governo. A incidência de benefício no município de Senhor do Bonfim, para 2003, foi estimada por grupos da população previamente definidos (renda, gênero e cor da pele, com o objetivo de avaliar o grau de iniqüidade dos gastos públicos em saúde. Os gastos públicos foram desagregados por nível de complexidade. Combinando os dados referentes aos subsídios com os resultados da pesquisa domiciliar, observou-se iniqüidade da distribuição dos gastos públicos com saúde em Senhor do Bonfim.The goal of this paper is to analyze inequality in the access and use of services of health in Senhor do Bonfim, city of the state of Bahia. It describes benefit incidence analysis, which allows to identify which social groups benefit governmental subsidies. The benefit incidence in Senhor do Bonfim, Bahia, was estimated, in 2003, for groups of the population previously defined (income, gender and race, with the objective of evaluating the inequity of the public expenditure in health in this city. The public expenses had been fragmented by complexity level. Combining the unit subsidies with the use patterns reported in the household survey reveals a very unequal distribution health spending in Senhor do Bonfim.

Average and local atomic-scale structure in BaZrxTi(1-x)O3 (x = 0. 10, 0.20, 0.40) ceramics by high-energy x-ray diffraction and Raman spectroscopy.

Science.gov (United States)

Buscaglia, Vincenzo; Tripathi, Saurabh; Petkov, Valeri; Dapiaggi, Monica; Deluca, Marco; Gajović, Andreja; Ren, Yang

2014-02-12

High-resolution x-ray diffraction (XRD), Raman spectroscopy and total scattering XRD coupled to atomic pair distribution function (PDF) analysis studies of the atomic-scale structure of archetypal BaZrxTi(1-x)O3 (x = 0.10, 0.20, 0.40) ceramics are presented over a wide temperature range (100-450 K). For x = 0.1 and 0.2 the results reveal, well above the Curie temperature, the presence of Ti-rich polar clusters which are precursors of a long-range ferroelectric order observed below TC. Polar nanoregions (PNRs) and relaxor behaviour are observed over the whole temperature range for x = 0.4. Irrespective of ceramic composition, the polar clusters are due to locally correlated off-centre displacement of Zr/Ti cations compatible with local rhombohedral symmetry. Formation of Zr-rich clusters is indicated by Raman spectroscopy for all compositions. Considering the isovalent substitution of Ti with Zr in BaZrxTi1-xO3, the mechanism of formation and growth of the PNRs is not due to charge ordering and random fields, but rather to a reduction of the local strain promoted by the large difference in ion size between Zr(4+) and Ti(4+). As a result, non-polar or weakly polar Zr-rich clusters and polar Ti-rich clusters are randomly distributed in a paraelectric lattice and the long-range ferroelectric order is disrupted with increasing Zr concentration.

Crystal structures and electronic properties of BaC2 isomers by theoretical study based on DFT

Institute of Scientific and Technical Information of China (English)

2008-01-01

Band structures and electronic properties of two BaC2 isomers were calculated by using density func-tional theory(DFT) properly.The ionic bond features are all typical between cation(Ba) and anion clusters(C2) in both structures of the isomers.However,a much stronger covalent bond exists in anion clusters which can be seen by inspecting the electron distribution contour that has a dull bell like shape between two carbon atoms.The shortest distance between Ba2+ and C22? and the bond length in anion clusters are different in these isomers of BaC2,which are 0.2945 nm and 0.1185 nm for the structure with the I4/mmm space group and 0.2744 and 0.1136 nm with the C2/c type,respectively.Band structures were clarified by combining the DOS to indicate the ionic bonding features more clearly.Population analysis provided further evidence on these ideas.Thermodynamical calculation results reveal that the transition temperature of these two polymorphs of BaC2 locates near 132 K,which is consistent with the recent experimental results.

Composition and phase analysis of nanocrystalline Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) by using general structure analysis system

Energy Technology Data Exchange (ETDEWEB)

Gunanto, Y. E., E-mail: yohanes.gunanto@uph.edu [Departement of Biology Education, Pelita Harapan University, Karawaci, Tangerang, 15811 (Indonesia); Jobiliong, E., E-mail: eric.jobiliong@uph.edu [Departement of Industrial Engineering, Pelita Harapan University, Karawaci, Tangerang, 15811 (Indonesia); Adi, Wisnu Ari, E-mail: dwisnuaa@batan.go.id [Centre for Sci. and Tech. of Adv. Materials, BATAN, Serpong, Tangerang Selatan, 15314 (Indonesia)

2016-03-11

Single phase of nanocrystalline Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) was successfully synthesized by mechanical milling method and thermal process. Stoichiometric quantities of analytical-grade SrCO{sub 3}, BaCO{sub 3}, and Fe{sub 2}O{sub 3}, were mixed and milled using a high-energy milling. The mixture of all precursors was sintered at a temperature of 1000 °C for 10 hours. The refinement of x-ray diffraction trace for all samples confirmed a single phase material with a hexagonal structure. The increase of the amount of strontium content in the barium atoms in the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} system can decrease the lattice parameter which have been successfully substituted into the barium atoms. The calculation result of cationic distribution showed that the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 0.6) and (x = 0.4) samples have nominal composition of Ba{sub 0,61}Sr{sub 0,39}Fe{sub 12}O{sub 19} and Ba{sub 0,37}Sr{sub 0,63}Fe{sub 12}O{sub 19}, respectively. Results of the mean of crystallite size evaluation for respective powder materials showed that the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) samples have the crystallite size of 22 nm, 25 nm and 34 nm, respectively. We concluded that the cationic distribution of barium atoms was successfully substituted by strontium atoms approaching the nominal stoichiometric composition.

Tl, Bi, and Pb doping in Ba4BiPb2TlO12-δ

International Nuclear Information System (INIS)

Sutto, T.E.; Averill, B.A.

1992-01-01

To determine the effects of different 6s metal concentrations on the superconducting nature of Ba 4 BiPb 2 TlO 12-δ , materials produced via four doping schemes were examined: Ba 4 Bi(Pb, Tl) 3 O 12-δ , Ba 4 -(BiPb) 3 TlO 12-δ , Ba 4 (Bi,Tl) 2 Pb 2 O 12-δ , and Ba 4 Bi x Pb 4-2x Tl x O 12-δ . For the parent compound a value of δ = 0.91 was observed, indicating that approximately 1/4 oxygen atom was missing per cubic subsection of the unit cell. For all samples, the symmetry of the parent compound changed from orthorhombic to tetragonal as the system moved away from the ideal composition. This was usually accompanied by the loss of superconductivity, which exhibited a maximum T c of 10.5 K for the parent compound Ba 4 BiPb 2 TlO 12-δ . Also reported are high-temperature magnetic susceptibility results, which are used to determine the effect of metal substitution on the density of states at the Fermi level. For each set of variants on the parent composition, the onset of superconductivity was accompanied by a significant decrease in the size of the Pauli paramagnetic signal. 16 refs., 6 figs

Ground-state hyperfine splitting for Rb, Cs, Fr, Ba+, and Ra+

Science.gov (United States)

Ginges, J. S. M.; Volotka, A. V.; Fritzsche, S.

2017-12-01

We have systematically investigated the ground-state hyperfine structure for alkali-metal atoms 87Rb,133Cs, and 211Fr and alkali-metal-like ions +135Ba and +225Ra, which are of particular interest for parity violation studies. The quantum electrodynamic one-loop radiative corrections have been rigorously evaluated within an extended Furry picture employing core-Hartree and Kohn-Sham atomic potentials. Moreover, the effect of the nuclear magnetization distribution on the hyperfine structure intervals has been studied in detail and its uncertainty has been estimated. Finally, the theoretical description of the hyperfine structure has been completed with full many-body calculations performed in the all-orders correlation potential method.

Two new ternary chalcogenides Ba{sub 2}ZnQ{sub 3} (Q = Se, Te) with chains of ZnQ{sub 4} tetrahedra. Syntheses, crystal structure, and optical and electronic properties

Energy Technology Data Exchange (ETDEWEB)

Prakash, Jai; Beard, Jessica; Malliakas, Christos D.; Ibers, James A. [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Mesbah, Adel [Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Bagnols-sur-Ceze (France); Rocca, Dario; Lebegue, Sebastien [Univ. de Lorraine, Vandoeuvre-les-Nancy (France). Lab. de Cristallographie, Resonance Magnetique et Modelisations (CRM2, UMR CNRS 7036)

2016-08-01

Single crystals of Ba{sub 2}ZnQ{sub 3} (Q = Se, Te) were obtained by solid-state reactions at 1173 K. These isostructural compounds crystallize in the K{sub 2}AgI{sub 3} structure type. The Zn atoms in this structure are coordinated to four Q atoms (2 Q1, 1 Q2, 1 Q3) and these form a distorted tetrahedron around each Zn atom. Each ZnQ{sub 4} tetrahedron shares two corners with neighboring ZnQ{sub 4} tetrahedra resulting in the formation of infinite chains of [ZnQ{sub 4}{sup 4-}] units. The absorption spectrum of a single crystal of Ba{sub 2}ZnTe{sub 3} shows an absorption edge at 2.10(2) eV, consistent with the dark-red color of the crystals. From DFT calculations Ba{sub 2}ZnSe{sub 3} and Ba{sub 2}ZnTe{sub 3} are found to be semiconductors with electronic band gaps of 2.6 and 1.9 eV, respectively.

Vacancy-induced magnetism in BaTiO3(001) thin films based on density functional theory.

Science.gov (United States)

Cao, Dan; Cai, Meng-Qiu; Hu, Wang-Yu; Yu, Ping; Huang, Hai-Tao

2011-03-14

The origin of magnetism induced by vacancies on BaTiO(3)(001) surfaces is investigated systematically by first-principles calculations within density-functional theory. The calculated results show that O vacancy is responsible for the magnetism of the BaO-terminated surface and the magnetism of the TiO(2)-terminated surface is induced by Ti vacancy. For the BaO-terminated surface, the magnetism mainly arises from the unpaired electrons that are localized in the O vacancy basin. In contrast, for the TiO(2)-terminated surface, the magnetism mainly originates from the partially occupied O-2p states of the first nearest neighbor O atoms surrounding the Ti vacancy. These results suggest the possibility of implementing magneto-electric coupling in conventional ferroelectric materials.

Effects of incident cluster size, substrate temperature, and incident energy on bombardment of Ni clusters onto Cu (0 0 1) surface studied using molecular dynamics simulation

International Nuclear Information System (INIS)

Lin, Shiang-Jiun; Wu, Cheng-Da; Fang, Te-Hua; Chen, Guan-Hung

2012-01-01

The bombardment process of a Ni cluster onto a Cu (0 0 1) surface is studied using molecular dynamics (MD) simulations based on the tight-binding second-moment approximation (TB-SMA) many-body potential. The effects of incident cluster size, substrate temperature, and incident energy are evaluated in terms of molecular trajectories, kinetic energy, stress, self-diffusion coefficient, and sputtering yield. The simulation results clearly show that the penetration depth and Cu surface damage increase with increasing incident cluster size for a given incident energy per atom. The self-diffusion coefficient and the penetration depth of a cluster significantly increase with increasing substrate temperature. An incident cluster can be scattered into molecules or atoms that become embedded in the surface after incidence. When the incident energy is increased, the number of volcano-like defects and the penetration depth increase. A high sputtering yield can be obtained by increasing the incident energy at high temperature. The sputtering yield significantly increases with cluster size when the incident energy is above 5 eV/atom.

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

DEFF Research Database (Denmark)

Wu, Wei; Feng, Feng; Yue, Zhao

2014-01-01

must be at least 2 for full conversion of the Ba-precursor to BaF2 to avoid the formation of BaCO3, which is detrimental to the superconducting performance of YBCO films. In this study, a solution with a 2:1 F/Ba mole ratio was developed, and the fluorine content of this solution was approximately only...... 10.3% of that used in the conventional TFA-MOD method. Attenuated total reflectance-Fourier transform-infrared spectra (ATR-FT-IR) revealed that BaCO3 was remarkably suppressed in the as-pyrolyzed film—and eliminated at 700 °C. Thus, YBCO films with a critical current density (Jc) of over 5 MA cm−2...... (77 K, 0 T, 200 nm thickness) could be obtained on lanthanum aluminate single-crystal substrates. In situ FT-IR spectra showed that no obvious fluorinated gaseous by-products were detected in the pyrolysis step, which indicated that all F atoms might remain in the film as fluorides. X-ray diffraction...

<90 day storage training plan for the 103-B, 1701-BA, AND 1714-C buildings

International Nuclear Information System (INIS)

Snider, P.M.

1996-10-01

The 103-B, 1701-BA, and 1714C < 90 Day Storage Area stores characteristic wastes generated in the demolition of the 103-B, 1701-BA, and 1714-C Complex. Wastes (lead-based painted components) are packaged and stored in vendor shipment containers. This is the Environmental Restoration Contractor team training plan for the 103-B, 1701-BA, and 1714-C subgrade demolition < 90 Day Storage of Hazardous Waste. This document is intended to meet the requirements of Washington Administrative Code 173-303-330 and the Hanford Dangerous Waste Permit. Training unrelated to compliance with WAC 173-303-330 is not addressed in this training plan. WAC 173-303-330(1)(d)(2, 5, 6) requires that personnel be familiarized, where applicable, with waste feed cut-off systems, response to ground-water contamination incidents, and shutdown of operations. These are not applicable to 103-B, 1701-BA, and 1714-C Subgrade Demolition < 90 Day Storage, and therefore are not covered in this training plan

Silencing of the rotavirus NSP4 protein decreases the incidence of biliary atresia in murine model.

Directory of Open Access Journals (Sweden)

Jiexiong Feng

Full Text Available Biliary atresia is a common disease in neonates which causes obstructive jaundice and progressive hepatic fibrosis. Our previous studies indicate that rotavirus infection is an initiator in the pathogenesis of experimental biliary atresia (BA through the induction of increased nuclear factor-kappaB and abnormal activation of the osteopontin inflammation pathway. In the setting of rotavirus infection, rotavirus nonstructural protein 4 (NSP4 serves as an important immunogen, viral protein 7 (VP7 is necessary in rotavirus maturity and viral protein 4 (VP4 is a virulence determiner. The purpose of the current study is to clarify the roles of NSP4, VP7 and VP4 in the pathogenesis of experimental BA. Primary cultured extrahepatic biliary epithelia were infected with Rotavirus (mmu18006. Small interfering RNA targeting NSP4, VP7 or VP4 was transfected before rotavirus infection both in vitro and in vivo. We analyzed the incidence of BA, morphological change, morphogenesis of viral particles and viral mRNA and protein expression. The in vitro experiments showed NSP4 silencing decreased the levels of VP7 and VP4, reduced viral particles and decreased cytopathic effect. NSP4-positive cells had strongly positive expression of integrin subunit α2. Silencing of VP7 or VP4 partially decreased epithelial injury. Animal experiments indicated after NSP4 silencing, mouse pups had lower incidence of BA than after VP7 or VP4 silencing. However, 33.3% of VP4-silenced pups (N = 6 suffered BA and 50% of pups (N = 6 suffered biliary injury after VP7 silencing. Hepatic injury was decreased after NSP4 or VP4 silencing. Neither VP4 nor VP7 were detected in the biliary ducts after NSP4. All together, NSP4 silencing down-regulates VP7 and VP4, resulting in decreased incidence of BA.

Data compilation of angular distributions of sputtered atoms

International Nuclear Information System (INIS)

Yamamura, Yasunori; Takiguchi, Takashi; Tawara, Hiro.

1990-01-01

Sputtering on a surface is generally caused by the collision cascade developed near the surface. The process is in principle the same as that causing radiation damage in the bulk of solids. Sputtering has long been regarded as an undesirable dirty effect which destroys the cathodes and grids in gas discharge tubes or ion sources and contaminates plasma and the surrounding walls. However, sputtering is used today for many applications such as sputter ion sources, mass spectrometers and the deposition of thin films. Plasma contamination and the surface erosion of first walls due to sputtering are still the major problems in fusion research. The angular distribution of the particles sputtered from solid surfaces can possibly provide the detailed information on the collision cascade in the interior of targets. This report presents a compilation of the angular distribution of sputtered atoms at normal incidence and oblique incidence in the various combinations of incident ions and target atoms. The angular distribution of sputtered atoms from monatomic solids at normal incidence and oblique incidence, and the compilation of the data on the angular distribution of sputtered atoms are reported. (K.I.)

Classroom: inexpensive models for teaching atomic structure and ...

African Journals Online (AJOL)

Classroom: inexpensive models for teaching atomic structure and compounds at junior secondary school level of education. WHK Hordzi, BA Mensah. Abstract. No Abstract. Global Journal of Educational Research Vol. 2(1&2) 2003: 33-40. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL ...

Reaction of cyanide with cytochrome ba3 from Thermus thermophilus: spectroscopic characterization of the Fe(II)a3-CN.Cu(II)B-CN complex suggests four 14N atoms are coordinated to CuB.

Science.gov (United States)

Surerus, K K; Oertling, W A; Fan, C; Gurbiel, R J; Einarsdóttir, O; Antholine, W E; Dyer, R B; Hoffman, B M; Woodruff, W H; Fee, J A

1992-01-01

Cytochrome ba3 from Thermus thermophilus reacts slowly with excess HCN at pH 7.4 to create a form of the enzyme in which CuA, cytochrome b, and CuB remain oxidized, while cytochrome a3 is reduced by one electron, presumably with the formation of cyanogen. We have examined this form of the enzyme by UV-visible, resonance Raman, EPR, and electron nuclear double resonance spectroscopies in conjunction with permutations of 13C- and 15N-labeled cyanide. The results support a model in which one CN- binds through the carbon atom to ferrous a3, supporting a low-spin (S = 0) configuration on the Fe; bridging by this cyanide to the CuB is weak or absent. Four 14N atoms, presumably donated by histidine residues of the protein, provide a strong equatorial ligand field about CuB; a second CN- is coordinated through the carbon atom to CuB in an axial position. PMID:1314380

Electron and positron atomic elastic scattering cross sections

International Nuclear Information System (INIS)

Stepanek, Jiri

2003-01-01

A method was developed to calculate the total and differential elastic-scattering cross sections for incident electrons and positrons in the energy range from 0.01 eV to 1 MeV for atoms of Z=1-100. For electrons, hydrogen, helium, nitrogen, oxygen, krypton, and xenon, and for positrons, helium, neon, and argon atoms were considered for comparison with experimental data. First, the variationally optimized atomic static potentials were calculated for each atom by solving the Dirac equations for bound electron states. Second, the Dirac equations for a free electron or positron are solved for an atom using the previously calculated static potential accomplished (in the case of electrons) by 'adjusted' Hara's exchange potential for a free-state particle. Additional to the exchange effects, the charge cloud polarization effects are considered applying the correlation-polarization potential of O'Connell and Lane (with correction of Padial and Norcross) for incident electrons, and of Jain for incident positrons. The total, cutoff and differential elastic-scattering cross sections are calculated for incident electrons and positrons with the help of the relativistic partial wave analysis. The solid state effects for scattering in solids are described by means of a muffin-tin model, i.e. the potentials of neighboring atoms are superpositioned in such a way that the resulting potential and its derivative are zero in the middle distance between the atoms. The potential of isolated atom is calculated up to the radius at which the long-range polarization potential becomes a value of -10 -8

Understanding Molecular Ion-Neutral Atom Collisions for the Production of Ultracold Molecular Ions

Science.gov (United States)

2016-06-06

2012): 0. doi: 10.1103/PhysRevLett.109.223002 Kuang Chen, Scott T. Sullivan, Wade G. Rellergert, Eric R. Hudson. Measurement of the Coulomb Logarithm...or fellowships for further studies in science, mathematics, engineering or technology fields: Student Metrics This section only applies to graduating...clouds of Ba+ ions and Ca atoms. Due to the strong Coulomb interaction, the Ba+ ions quickly cool the molecular ion translation motion, while the

New muonic-atom test of vacuum polarization

International Nuclear Information System (INIS)

Dixit, M.S.; Carter, A.L.; Hincks, E.P.; Kessler, D.; Wadden, J.S.; Hargrove, C.K.; McKee, R.J.; Mes, H.; Anderson, H.L.

1975-01-01

In order to check the discrepancy between calculation and experiment in muonic atoms, we have remeasured the 5g-4f transitions in Pb and the 5g-4f and the 4f-3d transitions in Ba. Our new results show no discrepancy and confirm recent theoretical calculations of vacuum polarization to within 0.5%

Spectral analysis of 5s25p2(6p+6d+7s) configurations of Ba VI

International Nuclear Information System (INIS)

Sharma, M.K.; Tauheed, A.; Rahimullah, K.

2014-01-01

The sixth spectrum of barium (Ba VI) has been investigated with the aid of experimental recordings made on a 3-m normal incidence vacuum spectrograph of Antigonish laboratory (Canada) in the wavelength region 300–2080 Å using triggered spark as an excitation source. The spectral analysis has been extended considerably to include new configuration the 5s 2 5p 2 6p in odd parity matrix and the 5s 2 5p 2 6d and 5s 2 5p 2 7s configurations in even parity matrix. Previously reported levels of the ground configuration (5s 2 5p 3 ) and three lowest excited configurations the 5s5p 4 , 5s 2 5p 2 5d and 5s 2 5p 2 6s have been confirmed and the two unknown levels of the 5s 2 5p 2 5d configuration with J=9/2, have now been established through the identification of transitions from the 5s 2 5p 2 6p levels. All twenty one levels of the 5s 2 5p 2 6p configuration and twenty nine levels out of thirty six of the 5s 2 5p 2 6d and 5s 2 5p 2 7s configurations have now been established. Hartree–Fock calculations involving configuration interactions support the analyses. The accuracy of our wavelength measurement is ±0.005 Å for sharp lines. - Highlights: • The spectrum of Ba was recorded on a 3-m spectrograph with triggered spark source. • Atomic transitions for Ba VI were identified to established new energy levels. • CI calculations with relativistic corrections were made for theoretical predictions. • Weighted oscillator strength (gf) and transition probabilities (gA) were calculated

Incidence of female breast cancer among atomic bomb survivors, 1950-1985

International Nuclear Information System (INIS)

Tokunaga, Masayoshi; Land, C.E.; Tokuoka, Shoji; Akiba, Suminori; Nishimori, Issei; Soda, Midori

1994-01-01

An incidence survey among atomic bomb survivors identified 807 breast cancer cases, and 20 second breast cancers. As in earlier surveys of the Life Span Study population, a strongly linear radiation dose response was found, with the highest dose-specific excess relative risk (ERR) among survivors under 20 years old at the time of the bombings. Sixty-eight of the cases were under 10 years old at exposure, strengthening earlier reports of a marked excess risk associated with exposure during infancy and childhood. A much lower, but marginally significant, dose response was seen among women exposed at 40 years and older. It was not possible, however to discriminate statistically between age at exposure and age at observation for risk as the more important determinant of ERR per unit dose. A 13-fold ERR at 1 Sv was found for breast cancer occurring before age 35, compared to a 2-fold excess after age 35, among survivors exposed before age 20. This a posteriori finding, based on 27 exposed, known-dose, early-onset cases, suggests the possible existence of a susceptible genetics subgroup. Further studies, involving family histories of cancer and investigations at the molecular level, are suggested to determine whether such a subgroup exists. 41 refs., 5 figs., 10 tabs

First-order character of the displacive structural transition in BaWO4

International Nuclear Information System (INIS)

Tan Da-Yong; Xiao Wan-Sheng; Zhou Wei; Chen Ming; Xiong Xiao-Lin; Song Mao-Shuang

2012-01-01

Nearly all displacive transitions have been considered to be continuous or second order, and the rigid unit mode (RUM) provides a natural candidate for the soft mode. However, in-situ X-ray diffraction and Raman measurements show clearly the first-order evidences for the scheelite-to-fergusonite displacive transition in BaWO 4 : a 1.6% volume collapse, coexistence of phases, and hysteresis on release of pressure. Such first-order signatures are found to be the same as the soft modes in BaWO 4 , which indicates the scheelite-to-fergusonite displacive phase transition hides a deeper physical mechanism. By the refinement of atomic displacement parameters, we further show that the first-order character of this phase transition stems from a coupling of large compression of soft BaO 8 polyhedrons to the small displacive distortion of rigid WO 4 tetrahedrons. Such a coupling will lead to a deeper physical insight in the phase transition of the common scheelite-structured compounds. (condensed matter: structural, mechanical, and thermal properties)

Synthesis and structure of heptaaqua(nitrilotris(methylenephosphonato))(dibarium)sodium monohydrate [Na(H{sub 2}O){sub 3}(μ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(μ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Somov, N. V., E-mail: somov@phys.unn.ru [Lobachevsky State University of Nizhny Novgorod (Russian Federation); Chausov, F. F., E-mail: xps@ftiudm.ru [Russian Academy of Sciences, Physical–Technical Institute, Ural Branch (Russian Federation); Zakirova, R. M., E-mail: ftt@udsu.ru [Udmurt State University (Russian Federation)

2017-03-15

Crystals of the monohydrate form of heptaaqua(nitrilotris(methylenephosphonato))(dibarium) sodium [Na(H{sub 2}O{sub )3}(µ{sup 6}-NH(CH{sub 2}PO{sub 3}){sub 3})(µ-H{sub 2}O){sub 3}Ba{sub 2}(H{sub 2}O)] · H{sub 2}O are obtained; space group P2{sub 1}/c, Z = 4; a = 13.9117(10) Å, b = 11.54030(10) Å, and c = 24.1784(17) Å, ß = 148.785(18)°. The Na atom is coordinated octahedrally by one oxygen atom of a phosphonate group and five water molecules, including two bridging molecules. Ba atoms occupy two inequivalent crystallographic positions with coordination number eight and nine. The coordination spheres of both Ba atoms include two water molecules. Each ligand is bound to one Na atom and five Ba atoms forming three Ba–O–P–O and five Ba–O–P–C–N–C–P–O chelate cycles. In addition to the coordination bonds, molecules, including the solvate water molecule, are involved in hydrogen bonds in the crystal packing.

High resolution structure of the ba3 cytochrome c oxidase from Thermus thermophilus in a lipidic environment.

Directory of Open Access Journals (Sweden)

Theresa Tiefenbrunn

Full Text Available The fundamental chemistry underpinning aerobic life on Earth involves reduction of dioxygen to water with concomitant proton translocation. This process is catalyzed by members of the heme-copper oxidase (HCO superfamily. Despite the availability of crystal structures for all types of HCO, the mode of action for this enzyme is not understood at the atomic level, namely how vectorial H(+ and e(- transport are coupled. Toward addressing this problem, we report wild type and A120F mutant structures of the ba(3-type cytochrome c oxidase from Thermus thermophilus at 1.8 Å resolution. The enzyme has been crystallized from the lipidic cubic phase, which mimics the biological membrane environment. The structures reveal 20 ordered lipid molecules that occupy binding sites on the protein surface or mediate crystal packing interfaces. The interior of the protein encloses 53 water molecules, including 3 trapped in the designated K-path of proton transfer and 8 in a cluster seen also in A-type enzymes that likely functions in egress of product water and proton translocation. The hydrophobic O(2-uptake channel, connecting the active site to the lipid bilayer, contains a single water molecule nearest the Cu(B atom but otherwise exhibits no residual electron density. The active site contains strong electron density for a pair of bonded atoms bridging the heme Fe(a3 and Cu(B atoms that is best modeled as peroxide. The structure of ba(3-oxidase reveals new information about the positioning of the enzyme within the membrane and the nature of its interactions with lipid molecules. The atomic resolution details provide insight into the mechanisms of electron transfer, oxygen diffusion into the active site, reduction of oxygen to water, and pumping of protons across the membrane. The development of a robust system for production of ba(3-oxidase crystals diffracting to high resolution, together with an established expression system for generating mutants, opens the

Molecular dynamics simulation for the influence of incident angles of energetic carbon atoms on the structure and properties of diamond-like carbon films

International Nuclear Information System (INIS)

Li, Xiaowei; Ke, Peiling; Lee, Kwang-Ryeol; Wang, Aiying

2014-01-01

The influence of incident angles of energetic carbon atoms (0–60°) on the structure and properties of diamond-like carbon (DLC) films was investigated by the molecular dynamics simulation using a Tersoff interatomic potential. The present simulation revealed that as the incident angles increased from 0 to 60°, the surface roughness of DLC films increased and the more porous structure was generated. Along the growth direction of DLC films, the whole system could be divided into four regions including substrate region, transition region, stable region and surface region except the case at the incident angle of 60°. When the incident angle was 45°, the residual stress was significantly reduced by 12% with little deterioration of mechanical behavior. The further structure analysis using both the bond angles and bond length distributions indicated that the compressive stress reduction mainly resulted from the relaxation of highly distorted C–C bond length. - Highlights: • The dependence of films properties on different incident angles was investigated. • The change of incident angles reduced the stress without obvious damage of density. • The stress reduction attributed to the relaxation of highly distorted bond length

Peso do baço como fator prognóstico do tratamento cirúrgico de pacientes portadores de esquistossomose mansônica

Directory of Open Access Journals (Sweden)

Álvaro Antônio Bandeira Ferraz

Full Text Available OBJETIVO: Analisar pré-operatoriamente o peso do baço como fator prognóstico do tratamento cirúrgico de pacientes portadores de esquistossomose mansônica. MÉTODOS: Foram analisados 114 pacientes, portadores de esquistossomose mansônica com antecedentes de hemorragia digestiva, submetidos a tratamento cirúrgico. Os pacientes foram divididos em três grupos: Grupo 1 - baço menor que 500 gramas (17; Grupo 2 - baço entre 500 e 1.000 gramas (58; Grupo 3 - baço acima de 1.000 gramas (39. RESULTADOS: No Grupo 1 a recidiva hemorrágica foi de 17,6%, trombose da veia porta de 5,9% e não houve mortalidade. A incidência de hiperesplenismo pré-operatório foi de 29,4% e o calibre da veia porta foi de 1,1cm. No Grupo 2 a recidiva hemorrágica foi de 15,5%, trombose da veia porta de 10,3% e a mortalidade de quatro pacientes (6,9% (dois pacientes no período pós-operatório e dois no seguimento tardio, hepatocarcinoma e hemorragia digestiva. A incidência de hiperesplenismo foi de 53,4% e o calibre médio da veia porta foi de 1,4cm. No Grupo 3 a recidiva hemorrágica foi de 12,8%, trombose da veia porta de 5,1% e uma mortalidade tardia de dois pacientes (linfoma e infarto agudo do miocárdio. A incidência de hiperesplenismo foi de 76,9% e o calibre da veia porta foi de 1,5cm. CONCLUSÕES: O peso do baço apresenta relação com o hiperesplenismo pré-operatório, calibre da veia porta e permanência hospitalar pós-operatória. Não encontramos relação com a incidência de varizes de fundo gástrico, recidiva de sangramento digestivo, trombose da veia porta, grau de fibrose periportal e dados bioquímicos.

Study of skin cancer incidence in Nagasaki atomic bomb survivors, 1958-85

International Nuclear Information System (INIS)

Sadamori, Naoki; Otake, Masanori; Honda, Takeo.

1993-03-01

The effects of exposure to ionizing radiation on skin cancer incidence in a cohort of atomic bomb (A-bomb) survivors in the Nagasaki Extended Life Span Study (LSS-E85) sample have been investigated. Among 25,942 exposed survivors at risk whose DS86 dose estimates were available, 47 cases of skin cancer including malignant melanoma were confirmed in the Nagasaki Tumor Registry during the period from 1 April 1958 to 31 December 1985. The dose-response relationship of skin cancer based on an additive relative risk model showed linearity without threshold, not a linear-quadratic curve. The excess relative risk (ERR) of 2.2 per gray in the LSS-E85 sample was highly significant (95% confidence limits: 0.5 to 5.0). In addition, the ERR of 3.1 per gray in the Adult Health Study (AHS) sample was also significant (95% confidence limits: 0.6 to 20.3). When dose equivalents based on a relative biological effectiveness of neutrons of 10 were used, the ERR in the former sample decreased to 2.0 per sievert (95% confidence limits: 0.7-4.5), and the risk in the latter group also declined, to 2.7 per sievert (95% confidence limits: 0.6-17.8). The ERRs did not differ significantly between males and females in the LSS-E85 and AHS samples, but a highly significant increase was observed for the ERR of age at exposure and time trend since exposure. The ERR of skin cancer cases including and excluding 4 malignant melanoma cases for the LSS-E85 sample (there were no malignant melanoma cases in the AHS sample) showed almost the same linear dose response. This is the first report to demonstrate a highly significant dose-response relationship between A-bomb exposure and skin cancer incidence. (author)

On stoichiometry and intermixing at the spinel/perovskite interface in CoFe2O4/BaTiO3 thin films.

Science.gov (United States)

Tileli, Vasiliki; Duchamp, Martial; Axelsson, Anna-Karin; Valant, Matjaz; Dunin-Borkowski, Rafal E; Alford, Neil McN

2015-01-07

The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces.

Conduction band edge effective mass of La-doped BaSnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

James Allen, S., E-mail: allen@itst.ucsb.edu; Law, Ka-Ming [Physics Department, University of California, Santa Barbara, California 93106-5100 (United States); Raghavan, Santosh; Schumann, Timo; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

2016-06-20

BaSnO{sub 3} has attracted attention as a promising material for applications requiring wide band gap, high electron mobility semiconductors, and moreover possesses the same perovskite crystal structure as many functional oxides. A key parameter for these applications and for the interpretation of its properties is the conduction band effective mass. We measure the plasma frequency of La-doped BaSnO{sub 3} thin films by glancing incidence, parallel-polarized resonant reflectivity. Using the known optical dielectric constant and measured electron density, the resonant frequency determines the band edge electron mass to be 0.19 ± 0.01. The results allow for testing band structure calculations and transport models.

Atomic scale investigation of planar defects in 0.95Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}–0.05BaTiO{sub 3} thin films on SrTiO{sub 3} (001) substrates

Energy Technology Data Exchange (ETDEWEB)

Jin, Xiao-Wei; Lu, Lu [The School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Mi, Shao-Bo, E-mail: shaobo.mi@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Cheng, Sheng; Liu, Ming [The School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Jia, Chun-Lin [The School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-08-15

Thin films of lead-free piezoelectric 0.95Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}–0.05BaTiO{sub 3} (0.95NBT–0.05BT) are epitaxially grown on single crystalline SrTiO{sub 3} (001) substrates at 800 °C, 850 °C and 900 °C, respectively, by a high-pressure sputtering deposition technique. The microstructure of the thin films is investigated by means of aberration-corrected scanning transmission electron microscopy. Planar defects are observed and the density of the defects increases with the increase of the film-growth temperature. Two types of planar defects in the films are studied at the atomic scale. One consists of groups of edge-sharing TiO{sub 6} octahedra with Bi atoms located between the TiO{sub 6} octahedral groups, and the other exists in the form of Na/Bi(Ba)−O{sub 2}−Na/Bi(Ba) layer parallel to the (010) plane of the films. Based on the structure feature of the planar defects, the propagation of the planar defects related to edge-sharing TiO{sub 6} octahedra within the films and from the film-substrate interface is discussed. Furthermore, the ordering of the planar defects is expected to form new structures. In comparison with the microstructure of 0.95NBT–0.05BT bulk materials, the appearance of the high-density planar defects observed within the films could be considered to be responsible for the difference in the physical properties between the bulk materials and the films. - Highlights: • NBT–BT films have been successfully prepared on SrTiO{sub 3} (001) substrates. • Complex planar defects of zigzag-like and Aurivillius-type have been determined. • The propagation of the planar defects in the films has been characterized. • The intergrowth of planar faults with NBT–BT structure units results in the formation of new structures. • The NBT–BT/SrTiO{sub 3} interface structure has been determined at the atomic scale.

CARNAÚBA: The Coherent X-Ray Nanoprobe Beamline for the Brazilian Synchrotron SIRIUS/LNLS

Science.gov (United States)

Tolentino, Hélio C. N.; Soares, Márcio M.; Perez, Carlos A.; Vicentin, Flávio C.; Abdala, Dalton B.; Galante, Douglas; Teixeira, Verônica de C.; de Araújo, Douglas H. C.; Westfahl, Harry, Jr.

2017-06-01

The CARNAÚBA beamline is the tender-to-hard X-ray (2 - 15 keV) scanning nanoprobe planned for the 4th generation storage ring SIRIUS at the LNLS. CARNAÚBA uses an undulator source with vertical linear polarization in a low-beta straight section and grazing incidence-focusing mirrors to create a nanoprobe at 143 m from the source. The beamline optic is based on KB mirrors and provides high brilliance at an achromatic focal spot down to the diffraction limit diameter of ˜30 nm with a working distance of ˜6 cm. These characteristics are crucial for studying nanometric samples in experiments involving complex stages and environments. The CARNAÚBA beamline aims to perform raster scans using x-ray fluorescence, x-ray absorption spectroscopy, x-ray diffraction and coherent x-ray imaging techniques. Computed tomography will extend these methods to three dimensions.

Perovskite BaBiO3 Transformed Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence.

Science.gov (United States)

Li, Hong; Zhao, Qing; Liu, Bo-Mei; Zhang, Jun-Ying; Li, Zhi-Yong; Guo, Shao-Qiang; Ma, Ju-Ping; Kuroiwa, Yoshihiro; Moriyoshi, Chikako; Zheng, Li-Rong; Sun, Hong-Tao

2018-04-14

Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Here we present the successful synthesis of stoichiometric layered BaBiO2.5 enabled by a non-topotactic phase transformation of perovskite BaBiO3. By analysing the synchrotron X-ray diffraction data using the maximum entropy method/Rietveld technique, we find that Bi forms unusual chemical bondings with four oxygen atoms, featuring one ionic bonding and three covalent bondings that results in an asymmetric coordination geometry. A broad range of photophysical characterizations reveal that this peculiar structure shows near-infrared luminescence differing from conventional Bi-bearing systems. Experimental and theoretical results lead us to propose the excitonic nature of luminescence. Our work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. We envisage that this work could inspire interest for the exploration of a range of materials containing heavier p-block elements, offering prospects for the finding of systems with unusual properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth of GaN single crystals by a Ca- and Ba-added Na flux method

Science.gov (United States)

Ukegawa, H.; Konishi, Y.; Fujimori, T.; Miyoshi, N.; Imade, M.; Yoshimura, M.; Kitaoka, Y.; Sasaki, T.; Mori, Y.

2011-02-01

GaN substrates are desirable for fabricating ultra-violet LEDs and LDs, and high-power and high-frequency transistors. High-quality GaN single crystals can be obtained by using Na flux method, but the growth habit of bulk crystals must be controlled. In this study, we investigated the effects of additives (Ca, Ba) on the growth habit and impurity concentration in the crystals. The aspect ratio (c/a) of the crystals was increased by increasing the amount of additives, showing that the growth habit could be changed from the pyramidal shape to the prism shape. Ba concentration was below the detection limit (1x1015 atoms/cm3).

Influence of the valence states of atoms on conducting properties of PrBa2Cu3O6+x

International Nuclear Information System (INIS)

Romanenko, A.I.; Zakharchuk, N.F.; Naumov, N.G.; Fedorov, V.E.; Paek, U.H.

1997-01-01

Pr 3+ valent state only was discovered in PrBa 2 Cu 3 O 6+x within the oxygen content range 0.4 ≤ x ≤ 0.6. Out of this range, Pr 4+ state appears also. All the samples obtained showed insulating behavior of resistivity r(T). In PrBa 2 Cu 3 O 6+x (0.4 ≤ x ≤ 0.6), the resistivity is Mott variable-range hopping conduction type and is connected with oxygen disorder only. Out of this range, the localization is much stronger; this increase is due to Pr 4+ /Pr 3+ position disorder. Also, the localization decreases after annealing at room temperature is the result of ordering. Thus, the absence of metallic (and therefore superconducting) state in PrBa 2 Cu 3 O 6+x is due to the presence of both Pr 4+ and Pr 4+ /Pr 3+ disorder

Hexagonal perovskites with cationic vacancies. 18. Structure of the rhombohedral 12 L-stacking polytypes Ba/sub 2/La/sub 2/Bsup(II)(W/sub 2/sup(VI)vacantO/sub 12/)

Energy Technology Data Exchange (ETDEWEB)

Rother, H J; Fadini, A; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-04-01

According to the intensity calcualtions for Ba/sub 2/La/sub 2/Zn(W/sub 2/vacantO/sub 12/) the compounds of this type crystallize in the space group R3m-Dsub(3d)/sup 5/ with the sequence (3)(1)equivalent (hhcc)/sub 3/. The refined, intensity related R' value is 5,8%. The octahedral net consists of blocks of three face connected octahedra which are linked to each other by corner sharing BO/sub 6/ octahedra. The cationic vacancies are located in the centers of the groups of three octahedra. The two tungsten atoms in the outer positions are displaces by about 0.13 A from their ideal positions in direction of the central void. The (Ba, La) atoms neighbouring a vacancy (all in hexagonal close packed (Ba, La)O/sub 3/ sheets) are also dislocated in direction of the void, while the (Ba, La) atoms in the cubic packed sheets maintain nearly their ideal positions. The vibrational spectra of the compounds Ba/sub 2/La/sub 2/ Bsup(II)(W/sub 2/vacantO/sub 12/) are discussed. The force constants for the W/sub 2/vacantO/sub 12/ groups (factor group and Ppoint Dsub(3d)) were calculated and compared with the correspoinding values of Re/sub 2/vacantO/sub 12/ and ReWvacantO/sub 12/ units.

Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

International Nuclear Information System (INIS)

Sundar, C.S.; Bharathi, A.; Ching, W.Y.; Jean, Y.C.; Hor, P.H.; Meng, R.L.; Huang, Z.J.; Chu, C.W.

1990-01-01

The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across T c , in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO 2 layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO 2 layers. In the Tl 2 Ba 2 Ca 2 Cu 3 O 10 system, an increase in lifetime is observed below T c , whereas in Tl 2 Ba 2 CaCu 2 O 8 , a decrease in lifetime is seen below T c . In the Tl 2 Ba 2 CuO 6 system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO 2 layer in the superconducting state

Development of BaO-ZnO-B2O3 glasses as a radiation shielding material

Science.gov (United States)

Chanthima, N.; Kaewkhao, J.; Limkitjaroenporn, P.; Tuscharoen, S.; Kothan, S.; Tungjai, M.; Kaewjaeng, S.; Sarachai, S.; Limsuwan, P.

2017-08-01

The effects of the BaO on the optical, physical and radiation shielding properties of the xBaO: 20ZnO: (80-x)B2O3, where x=5, 10, 15, 20 and 25 mol%, were investigated. The glasses were developed by the conventional melt-quenching technique at 1400 °C with high purity chemicals of H3BO3, ZnO, and BaSO4. The optical transparency of the glasses indicated that the glasses samples were high, as observed by visual inspections. The mass attenuation coefficients (μm), the effective atomic numbers (Zeff), and the effective electron densities (Ne) were increased with the increase of BaO concentrations, and the decrease of gamma-ray energy. The developed glass samples were investigated and compared with the shielding concretes and glasses in terms of half value layer (HVL). The overall results demonstrated that the developed glasses had good shielding properties, and highly practical potentials in the environmental friendly radiation shielding materials without an additional of Pb.

Tuning the magnetism of the top-layer FeAs on BaFe2As2 (001): First-principles study

Science.gov (United States)

Zhang, Bing-Jing; Liu, Kai; Lu, Zhong-Yi

2018-04-01

Magnetism may play an important role in inducing the superconductivity in iron-based superconductors. As a prototypical system, the surface of BaFe2As2 provides a good platform for studying related magnetic properties. We have designed systematic first-principles calculations to clarify the surface magnetism of BaFe2As2 (001), which previously has received little attention in comparison with surface structures and electronic states. We find that the surface environment has an important influence on the magnetic properties of the top-layer FeAs. For As-terminated surfaces, the magnetic ground state of the top-layer FeAs is in the staggered dimer antiferromagnetic (AFM) order, distinct from that of the bulk, while for Ba-terminated surfaces the collinear (single-stripe) AFM order is the most stable, the same as that in the bulk. When a certain coverage of Ba or K atoms is deposited onto the As-terminated surface, the calculated energy differences among different AFM orders for the top-layer FeAs on BaFe2As2 (001) can be much reduced, indicating enhanced spin fluctuations. To compare our results with available scanning tunneling microscopy (STM) measurements, we have simulated the STM images of several structural/magnetic terminations. Astonishingly, when the top-layer FeAs is in the staggered dimer AFM order, a stripe pattern appears in the simulated STM image even when the surface Ba atoms adopt a √{2 }×√{2 } structure, while a √{2 }×√{2 } square pattern comes out for the 1 ×1 full As termination. Our results suggest: (i) the magnetic state at the BaFe2As2 (001) surface can be quite different from that in the bulk; (ii) the magnetic properties of the top-layer FeAs can be tuned effectively by surface doping, which may likely induce superconductivity at the surface layer; (iii) both the surface termination and the AFM order in the top-layer FeAs can affect the STM image of BaFe2As2 (001), which needs to be taken into account when identifying the surface

From Ba{sub 3}Ta{sub 5}O{sub 14}N to LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}: Decreasing the optical band gap of a photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Anke, B. [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Bredow, T. [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstr. 4, 53115 Bonn (Germany); Pilarski, M.; Wark, M. [Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); Lerch, M., E-mail: martin.lerch@tu-berlin.de [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany)

2017-02-15

Yellow LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba{sub 3}Ta{sub 5}O{sub 14}N and mixed-valence Ba{sub 3}Ta{sup V}{sub 4}Ta{sup IV}O{sub 15}. The electronic structure of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba{sub 3}Ta{sub 5}O{sub 14}N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba{sub 3}Ta{sub 5}O{sub 14}N revealing significantly higher activity for LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} with the results of the Rietveld refinements. Inset: Unit cell of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}. • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H{sub 2} evolution rate compared to prior tested Ba{sub 3}Ta{sub 5}O{sub 14}N.

Optics with an Atom Laser Beam

International Nuclear Information System (INIS)

Bloch, Immanuel; Koehl, Michael; Greiner, Markus; Haensch, Theodor W.; Esslinger, Tilman

2001-01-01

We report on the atom optical manipulation of an atom laser beam. Reflection, focusing, and its storage in a resonator are demonstrated. Precise and versatile mechanical control over an atom laser beam propagating in an inhomogeneous magnetic field is achieved by optically inducing spin flips between atomic ground states with different magnetic moment. The magnetic force acting on the atoms can thereby be effectively switched on and off. The surface of the atom optical element is determined by the resonance condition for the spin flip in the inhomogeneous magnetic field. More than 98% of the incident atom laser beam is reflected specularly

Grazing incidence collisions of ions and atoms with surfaces: from charge exchange to atomic diffraction; Collisions rasantes d'ions ou d'atomes sur les surfaces: de l'echange de charge a la diffraction atomique

Energy Technology Data Exchange (ETDEWEB)

Rousseau, P

2006-09-15

This thesis reports two studies about the interaction with insulating surfaces of keV ions or atoms under grazing incidence. The first part presents a study of charge exchange processes occurring during the interaction of singly charged ions with the surface of NaCl. In particular, by measuring the scattered charge fraction and the energy loss in coincidence with electron emission, the neutralization mechanism is determined for S{sup +}, C{sup +}, Xe{sup +}, H{sup +}, O{sup +}, Kr{sup +}, N{sup +}, Ar{sup +}, F{sup +}, Ne{sup +} and He{sup +}. These results show the importance of the double electron capture as neutralization process for ions having too much potential energy for resonant capture and not enough for Auger neutralization. We have also studied the ionisation of the projectile and of the surface, and the different Auger-like neutralization processes resulting in electron emission, population of conduction band or excited state. For oxygen scattering, we have measured an higher electron yield in coincidence with scattered negative ion than with scattered atom suggesting the transient formation above the surface of the oxygen doubly negative ion. The second study deals with the fast atom diffraction, a new phenomenon observed for the first time during this work. Due to the large parallel velocity, the surface appears as a corrugated wall where rows interfere. Similarly to the Thermal Atom Scattering the diffraction pattern corresponds to the surface potential and is sensitive to vibrations. We have study the H-NaCl and He-LiF atom-surface potentials in the 20 meV - 1 eV range. This new method offers interesting perspectives for surface characterisation. (author)

Half-metallic ferromagnetism in Fe, Co and Ni doped BaS: First principles calculations

Science.gov (United States)

Maurya, Savita; Sharma, Ramesh; Bhamu, K. C.

2018-04-01

The first principle investigation of structural, electronic, magnetic and optical properties of Ba1-xTMxS (x = 0.25) have been done using FPLAW method within the density functional theory (DFT) using generalized gradient approximation (GGA) for exchange correlation potential using two different functionals which are the PBE-sol and the modified Becke and Johnson local (spin) density approximation (mBJLDA). It was found that mBJLDA functional offer better account for the electronic structure of the Fe, Co and Ni-doped BaS. It was also observed that Fe/Co/Ni d, S p and Ba d states play a major role in determining the electronic properties of this alloy system. Investigation results shows that Ba0.75(Fe/Co/Ni)0.25S is ferromagnetic with magnetic moment of 3.72 µB, 2.73908 µB and 1.74324 µB at Fe, Co and Ni sites respectively. Complex dielectric constant ɛ(ω) and normal incidence reflectivity R(ω) are also been investigate for broad range of photon energies. These results are compared with the some reported existing experimental values.

Epitaxial c-axis oriented BaTiO3 thin films on SrTiO3-buffered Si(001) by atomic layer deposition

International Nuclear Information System (INIS)

Ngo, Thong Q.; McDaniel, Martin D.; Ekerdt, John G.; Posadas, Agham B.; Demkov, Alexander A.; Hu, Chengqing; Yu, Edward T.; Bruley, John

2014-01-01

Atomic layer deposition (ALD) of epitaxial c-axis oriented BaTiO 3 (BTO) on Si(001) using a thin (1.6 nm) buffer layer of SrTiO 3 (STO) grown by molecular beam epitaxy is reported. The ALD growth of crystalline BTO films at 225  °C used barium bis(triisopropylcyclopentadienyl), titanium tetraisopropoxide, and water as co-reactants. X-ray diffraction (XRD) reveals a high degree of crystallinity and c-axis orientation of as-deposited BTO films. Crystallinity is improved after vacuum annealing at 600  °C. Two-dimensional XRD confirms the tetragonal structure and orientation of 7–20-nm thick films. The effect of the annealing process on the BTO structure is discussed. A clean STO/Si interface is found using in-situ X-ray photoelectron spectroscopy and confirmed by cross-sectional scanning transmission electron microscopy. The capacitance-voltage characteristics of 7–20 nm-thick BTO films are examined and show an effective dielectric constant of ∼660 for the heterostructure

The new barium mercuride BaHg6 and ternary indium and gallium derivatives

International Nuclear Information System (INIS)

Wendorff, Marco; Röhr, Caroline

2013-01-01

Highlights: ► The new binary Hg-rich mercuride BaHg 6 crystallizes with a singular structure type. ► Ternary In substituted compounds are isotypic, whereas Ga substituted compounds are only structurally related. ► Structure relation to other Hg-rich alkali and alkaline earth mercurides. ► Discussion of covalent and metallic bonding aspects, as found by structure features and band structure calculations. - Abstract: The new binary barium mercuride BaHg 6 and the derived ternary indium and gallium containing compounds BaIn 1.2 Hg 4.8 and BaGa 0.8 Hg 5.2 were synthesized from melts of the elements, which were slowly cooled from 500 to 200 °C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The binary mercuride BaHg 6 (Pnma, a = 1338.9(3), b = 519.39(13), c = 1042.6(4) pm, Z = 4, R1 = 0.0885) and the isotypic indium substituted compound BaIn 1.2 Hg 4.8 as well as the structurally related gallium mercuride BaGa 0.8 Hg 5.2 (Cmcm, a = 729.77(7), b = 1910.1(2), c = 507.48(5) pm, Z = 4, R1 = 0.0606) crystallize with new structure types. Common features of both structures are planar nets of five- and eight-membered Hg rings, stacked perpendicular to the shortest axes. According to their lengths, the Hg–Hg bonds can be classified into three groups: strong, short ones (I, 285–292 pm), which are only found inside the nets, and longer distances (II), still carrying bond critical points, around 300 pm. Further contacts (III) serve to complete the coordination spheres of Hg/M (320–358 pm). The overall coordination numbers of Hg/M range from 10 to 13. The Ba cations are positioned in the centers of the octagons of the Hg/M nets, thus exhibiting a 5:8:5, i.e. 18, coordination by Hg/M atoms. DFT calculations of the electronic band structure of pure BaHg 6 and ordered models of the indium ( ′ BaInHg 5 ′ ) and the gallium ( ′ BaGaHg 5 ′ ) mercurides were performed using the FP-LAPW method. The calculated Bader charges

Simulations of the azimuthal distribution of low-energy H atoms scattered off Ag(1 1 0) at grazing incidence: DFT many-body versus model pair potentials

CERN Document Server

Cafarelli, P; Benazeth, C; Nieuwjaer, N; Lorente, N

2003-01-01

We compare the azimuthal distribution of H atoms after scattering off Ag(1 1 0) obtained by molecular dynamics with different H-Ag(1 1 0) potential energy surfaces (PES) and experimental results. We use grazing incident H atoms and low energies (up to 4 keV). Density functional theory (DFT) calculations are performed for the static case of an H atom in front of an Ag(1 1 0) surface. The surface is represented by an 8-atom slab, and the H atoms form 1x1 and 2x2 supercells. The generalized gradient approximation is used. Classical trajectories are evaluated on the obtained PES, and the azimuthal distribution of the scattered atoms is calculated. Good agreement with experiment is obtained which gives us some confidence in the correct description of the system at low energies by the static DFT calculations. These results are also compared with pair-potential calculations. The accuracy of trajectories may be important for the correct evaluation of charge transfer, energy loss and straggling during ion-surface coll...

Epitaxial growth and electronic structure of a layered zinc pnictide semiconductor, β-BaZn2As2

International Nuclear Information System (INIS)

Xiao, Zewen; Ran, Fan-Yong; Hiramatsu, Hidenori; Matsuishi, Satoru; Hosono, Hideo; Kamiya, Toshio

2014-01-01

BaZn 2 As 2 is expected for a good p-type semiconductor and has two crystalline phases of an orthorhombic α phase and a higher-symmetry tetragonal β phase. Here, we report that high-quality epitaxial films of the tetragonal β-BaZn 2 As 2 were grown on single-crystal MgO (001) substrates by a reactive solid-phase epitaxy technique. Out-of-plane and in-plane epitaxial relationships between the film and the substrate were BaZn 2 As 2 (00 l)//MgO (001) and BaZn 2 As 2 [200]//MgO [200], respectively. The full-widths at half maximum were 0.082° for a 008 out-of-plane rocking curve and 0.342° for a 200 in-plane rocking curve. A step-and-terrace structure was observed by atomic force microscopy. The band gap of β-BaZn 2 As 2 was evaluated to be around 0.2 eV, which is much smaller than that of a family compound LaZnOAs (1.5 eV). Density functional theory calculation using the Heyd–Scuseria–Ernzerhof hybrid functionals supports the small band gap. - Highlights: • High-quality epitaxial β-BaZn 2 As 2 films were obtained. • The band gap of β-BaZn 2 As 2 was evaluated to around 0.2 eV. • Hybrid Heyd–Scuseria–Ernzerhof calculation supports the small band gap

X-ray photoelectron spectroscopy study of BaWO{sub 4} and Ba{sub 2}CaWO{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Capece, Angela M., E-mail: acapece@pppl.gov [California Institute of Technology, Pasadena, CA (United States); Polk, James E. [Jet Propulsion Laboratory, Pasadena, CA (United States); Shepherd, Joseph E. [California Institute of Technology, Pasadena, CA (United States)

2014-12-15

Highlights: • XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented. • Binding energies of Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than Ba{sub 2}CaWO{sub 6}. • Ca 2p spectrum contains two sets of Ca 2p doublets attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}. - Abstract: XPS reference spectra for Ba{sub 2}CaWO{sub 6} and BaWO{sub 4} are presented, including high resolution spectra of the Ba 3d, W 4f, C 1s, Ca 2p, and O 1s lines. The peak locations and full widths at half maximum are also given. The binding energies of the Ba 3d and W 4f lines are 0.7 eV higher for BaWO{sub 4} than for Ba{sub 2}CaWO{sub 6}. The Ca 2p spectrum contains two sets of Ca 2p doublets that were attributed to Ba{sub 2}CaWO{sub 6} and CaCO{sub 3}.

Engaging the Terminal: Promoting Halogen Bonding Interactions with Uranyl Oxo Atoms.

Science.gov (United States)

Carter, Korey P; Kalaj, Mark; Surbella, Robert G; Ducati, Lucas C; Autschbach, Jochen; Cahill, Christopher L

2017-11-02

Engaging the nominally terminal oxo atoms of the linear uranyl (UO 2 2+ ) cation in non-covalent interactions represents both a significant challenge and opportunity within the field of actinide hybrid materials. An approach has been developed for promoting oxo atom participation in a range of non-covalent interactions, through judicious choice of electron donating equatorial ligands and appropriately polarizable halogen-donor atoms. As such, a family of uranyl hybrid materials was generated based on a combination of 2,5-dihalobenzoic acid and aromatic, chelating N-donor ligands. Delineation of criteria for oxo participation in halogen bonding interactions has been achieved by preparing materials containing 2,5-dichloro- (25diClBA) and 2,5-dibromobenzoic acid (25diBrBA) coupled with 2,2'-bipyridine (bipy) (1 and 2), 1,10-phenanthroline (phen) (3-5), 2,2':6',2''-terpyridine (terpy) (6-8), or 4'-chloro-2,2':6',2''-terpyridine (Cl-terpy) (9-10), which have been characterized through single crystal X-ray diffraction, Raman, Infrared (IR), and luminescence spectroscopy, as well as through density functional calculations of electrostatic potentials. Looking comprehensively, these results are compared with recently published analogues featuring 2,5-diiodobenzoic acid which indicate that although inclusion of a capping ligand in the uranyl first coordination sphere is important, it is the polarizability of the selected halogen atom that ultimately drives halogen bonding interactions with the uranyl oxo atoms. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Numerical solutions of anharmonic vibration of BaO and SrO molecules

Energy Technology Data Exchange (ETDEWEB)

Pramudito, Sidikrubadi; Sanjaya, Nugraha Wanda [Theoretical Physics Division, Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia); Sumaryada, Tony, E-mail: tsumaryada@ipb.ac.id [Theoretical Physics Division, Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia); Computational Biophysics and Molecular Modeling Research Group (CBMoRG), Department of Physics, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga Bogor 16680 (Indonesia)

2016-03-11

The Morse potential is a potential model that is used to describe the anharmonic behavior of molecular vibration between atoms. The BaO and SrO molecules, which are two almost similar diatomic molecules, were investigated in this research. Some of their properties like the value of the dissociation energy, the energy eigenvalues of each energy level, and the profile of the wavefunctions in their correspondence vibrational states were presented in this paper. Calculation of the energy eigenvalues and plotting the wave function’s profiles were performed using Numerov method combined with the shooting method. In general we concluded that the Morse potential solved with numerical methods could accurately produce the vibrational properties and the wavefunction behavior of BaO and SrO molecules from the ground state to the higher states close to the dissociation level.

Electronic structure and transport properties of Ba2Cd2Pn3 (Pn = As and Sb): An efficient materials for energy conversion

International Nuclear Information System (INIS)

Reshak, A.H.

2016-01-01

The full potential method within the recently modified Becke-Johnson potential explore that the Ba 2 Cd 2 Pn 3 (Pn = As and Sb) compounds are narrow band gap semiconductors of about 0.49 and 0.32 eV, which confute the finding of the previous TB-LMTO-ASA calculation that Ba 2 Cd 2 Sb 3 is a poor metal. It has been found that there are subtle difference in band desperations of the two compounds, resulting in significant influence on the electronic and transport properties, taking into account the size and the electro-negativity differences between As and Sb atoms. Calculation show that there exists a strong hybridization between the orbitals which may lead to form covalent bonding which is more favorable for the transport of the carriers than ionic one. The electronic structure, the anisotropy and the inter-atomic interactions are further analyzed by calculating the valence electronic charge density distribution in two crystallographic planes. The semi-classical Boltzmann theory as incorporated in BoltzTraP code was used to calculate the transport properties of Ba 2 Cd 2 As 3 and Ba 2 Cd 2 Sb 3 at different temperatures and chemical potentials to ascertain the influence of temperatures and substituting As by Sb on the transport properties. The carries mobility decreases with increasing the temperature also with increasing the carriers concentration. We have observed that substituting As by Sb lead to increase the carries mobility of Ba 2 Cd 2 Sb 3 along the whole temperature interval and the carries concentration range. It has been found that Ba 2 Cd 2 As 3 exhibit higher carriers concentration, electronic electrical conductivity and Seebeck coefficient than that of Ba 2 Cd 2 Sb 3 along the investigated temperature range. The highest value of Seebeck coefficient occurs at 300 K, which show good agreement with the experimental data. The power factor increases linearly with increasing the temperature and Ba 2 Cd 2 As 3 exhibit a bit higher power factor than that of Ba

FREQUENCY REDISTRIBUTION OF POLARIZED LIGHT IN THE Λ-TYPE MULTI-TERM POLARIZED ATOM

Energy Technology Data Exchange (ETDEWEB)

Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Sainz, R. Manso [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-06-20

We study the effects of Rayleigh and Raman scattering on the formation of polarized spectral lines in a Λ-type multi-term atom. We fully take into account the partial redistribution of frequency and the presence of atomic polarization in the lower states of the atomic model. Problems that can be modeled with this formalism include, for example, the formation of the Ca ii H–K and IR triplet, the analogous system of Ba ii, and the Ly β –H α system of hydrogenic ions.

Polarization reversal in BaTiO{sub 3} nanostructures synthesized by microwave-assisted hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Velasco-Davalos, Ivan; Ambriz-Vargas, Fabian [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Gómez-Yáñez, Carlos [Departamento de Ingeniería en Metalurgia y Materiales, ESIQIE, Instituto Politécnico Nacional, UPALM, Zacatenco, CP 07738 DF, México (Mexico); Thomas, Reji, E-mail: reji.thomas@emt.inrs.ca [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Ruediger, Andreas, E-mail: ruediger@emt.inrs.ca [Centre Énergie, Matériaux et Télécommunications, INRS, 1650 Lionel-Boulet, Varennes, Québec J3X1S2 (Canada)

2016-05-15

Ferroelectric BaTiO{sub 3} nanostructures and thin films were deposited by a microwave assisted hydrothermal process at low temperatures (<250 °C) on metallic Pt/Al{sub 2}O{sub 3}/SiO{sub 2}/Si and Nb:SrTiO{sub 3} (100) substrates. TiO{sub 2} nanoparticles dispersed in the Ba(OH){sub 2} alkaline solution are used as the precursors without any mineralizers. The incorporation of H{sub 2}O{sub 2} into precursor solution served as a strong oxidant and catalyst for the uniform nucleation of BaTiO{sub 3} on the substrate surface. The polycrystalline and epitaxial nature of the films were confirmed by atomic force microscopy and x-ray diffraction studies. We report the ferroelectric behavior of BaTiO{sub 3} films on Nb:SrTiO{sub 3} (100) substrates by piezoresponse force microscopy. - Highlights: • Microwave assisted hydrothermal deposition of highly ordered BaTiO{sub 3} thin films on single crystal substrates. • Fast growth without the needof any mineralizers. • Moderate addition of H{sub 2}O{sub 2} significantly improves the surface coverage. • H{sub 2}O{sub 2} substantially reduces hydrogen incorporation into the film and the associated leakage current. • Out-of-plane polarization reversal demonstrated locally.

Oxygen-vacancy defects on BaTiO3 (001) surface: a quantum chemical study

International Nuclear Information System (INIS)

Duque, Carlos; Stashans, Arvids

2003-01-01

A quantum-chemical study of technologically important BaTiO 3 crystal and oxygen-vacancy defects on its (001) surface is reported in the present work. The computations are made using a quantum-chemical method developed for periodic systems (crystals), which is based on the Hartree-Fock theory. The atomic rearrangement due to the surface creation is obtained for a pure BaTiO 3 by means of the periodic large unit cell (LUC) model and using an automated geometry optimisation procedure. The same technique is employed to study the electronic and structural properties of the material due to the presence of an O vacancy and F centre (two electrons trapped in an oxygen vacancy). The computations are carried out for both cubic and tetragonal lattices

Structure and microstructure of hexagonal Ba3Ti2RuO9 by electron diffraction and microscopy

International Nuclear Information System (INIS)

Maunders, C.; Etheridge, J.; Whitfield, H.J.

2005-01-01

We have used electron microscopy and diffraction to refine the structure and investigate the microstructure of Ba 3 Ti 2 RuO 9 . The parent compound is hexagonal BaTiO 3 with the space group P6 3 /mmc. Using convergent-beam electron diffraction (CBED) combined with electron-sensitive image plates we have found that the space group of Ba 3 Ti 2 RuO 9 is the non-centrosymmetric group P6 3 mc. at room temperature and at ∝ 110 K. This is consistent with the Ru and Ti atoms occupying alternate face-sharing octahedral sites in the h0001i direction. This maintains the c-glide, but breaks the mirror normal to the c axis and consequently removes the centre of symmetry. Using powder X-ray diffraction, we have measured the lattice parameters from polycrystalline samples to be a = 5.7056 ± 0.0005, c = 14.0093 ± 0.0015 Aa at room temperature. Using high-resolution electron microscopy (HREM) we observed highly coherent, low-strain {10 anti 10} grain boundaries intersecting at 60 and 120 . From CBED we deduce that adjacent grains are identical but for the relative phase of the Ti and Ru atom ordering along the c axis. HREM also revealed occasional stacking faults, normal to the c-axis

Electronic structure, Fermi surface topology and spectroscopic optical properties of LaBaCo{sub 2}O{sub 5.5} compound

Energy Technology Data Exchange (ETDEWEB)

Reshak, A.H. [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Al-Douri, Y. [Institute of Nano Electronic Engineering, University Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Khan, Wilayat; Khan, Saleem Ayaz [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic); Azam, Sikander, E-mail: sikander.physicst@gmail.com [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, Pilsen 306 14 (Czech Republic)

2014-08-01

We have investigated the electronic band structure, Fermi surface topology, chemical bonding and optical properties of LaBaCo{sub 2}O{sub 5.5} compound. The first-principle calculations based on density functional theory (DFT) by means of the full-potential linearized augmented plane-wave method were employed. The atomic positions of LaBaCo{sub 2}O{sub 5.5} compound were optimized by minimizing the forces acting on atoms. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel–Vosko GGA (EVGGA) to treat the exchange correlation potential by solving Kohn–Sham equations. Electronic structure and bonding properties are studied throughout the calculation of densities of states, Fermi surfaces and charge densities. Furthermore, the optical properties are investigated via the calculation of the dielectric tensor component in order to characterize the linear optical properties. Optical spectra are analyzed by means of the electronic structure, which provides theoretical understanding of the conduction mechanism of the investigated compound. - Highlights: • DFT-FPLAPW method used for calculating the properties of LaBaCo{sub 2}O{sub 5.5} compound. • This study shows that nature of the compound is metallic. • Crystallographic plane which shows covalent character of O–Co bond. • The optical properties were also calculated and analyzed. • The Fermi surface of LaBaCo{sub 2}O{sub 5.5} is composed of five bands crossing along Γ–Z direction.

Accurate determination of the composition of Y-Ba-Cu-O superconductor by spectrophotometry, gravimetry and flame AAS

International Nuclear Information System (INIS)

Bruneel, E; Verbauwhede, D; Vyver, D Van de; Schaubroeck, J; Hoste, S; Driessche, I Van

2005-01-01

A procedure for the accurate analytical determination of yttrium, barium and copper in an YBa 2 Cu 3 O x superconductor is described. After dissolution of the material the concentration of Y and Cu was spectrophotometrically determined as an Y-Arsenazo III and a Cu-Nitroso-R-salt complex, respectively. Ba was determined either gravimetrically as BaCrO 4 , after precipitation using a K 2 CrO 4 solution or using flame atomic absorption spectroscopy (AAS). An accuracy better than 0.7% and a coefficient of variation better then 1.2% are obtained. It is illustrated that this analytical procedure can be used to determine the composition of a bulk superconducting YBa 2 Cu 3 O x sample. For determination of Ba in thin films we suggest the use of flame AAS, with an accuracy of 0.03% and a coefficient of variation of 1.7%

Impact of anatomical variations of the circle of Willis on the incidence of aneurysms and their recurrence rate following endovascular treatment

International Nuclear Information System (INIS)

Songsaeng, D.; Geibprasert, S.; Willinsky, R.; Tymianski, M.; TerBrugge, K.G.; Krings, T.

2010-01-01

Aim: To analyse the impact of anatomical variations of the parent arteries on the incidence and recurrence rate following coil embolization of aneurysms of the anterior (AcoA), posterior communicating artery (PcoA) and basilar artery (BA) tip. Methods: Two hundred and two (96 AcoA, 67 PcoA, and 29 BA) aneurysms in 200 patients were treated with coil embolization between January 2000 and April 2008. Parent artery variations at each location were classified as: AcoA: A1 aplasia versus hypoplasia versus symmetrical size; PcoA: foetal origin versus medium versus small size, BA: cranial versus caudal versus asymmetrical fusion. The incidence of aneurysms and difference between recurrence rates for each group were recorded on follow-up. Results: AcoA, PcoA, and BA aneurysms were more often associated with embryonically earlier vessel wall dispositions (A1 aplasia, foetal PcoA, asymmetrical fusion). Two of these variations were also associated with aneurysm recurrence following coil embolization: asymmetrical A1 segment (p = 0.01), and asymmetrical BA tip (p = 0.02). Conclusions: AcoA, PcoA, and BA tip aneurysms tend to occur more often in anatomically variant parent artery dispositions, some of which are related to aneurysm recurrence following coil embolization. This may relate to a more fragile vessel disposition as it is not fully matured or to altered haemodynamics secondary to the anatomical variations.

Impact of anatomical variations of the circle of Willis on the incidence of aneurysms and their recurrence rate following endovascular treatment

Energy Technology Data Exchange (ETDEWEB)

Songsaeng, D. [Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto (Canada); Department of Radiology, Siriraj Hospital, Faculty of Medicine, Mahidol University, Bangkok (Thailand); Geibprasert, S.; Willinsky, R. [Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto (Canada); Tymianski, M. [Department of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto (Canada); TerBrugge, K.G. [Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto (Canada); Krings, T., E-mail: timo.krings@uhn.on.c [Division of Neuroradiology, Department of Medical Imaging, University of Toronto, Toronto (Canada)

2010-11-15

Aim: To analyse the impact of anatomical variations of the parent arteries on the incidence and recurrence rate following coil embolization of aneurysms of the anterior (AcoA), posterior communicating artery (PcoA) and basilar artery (BA) tip. Methods: Two hundred and two (96 AcoA, 67 PcoA, and 29 BA) aneurysms in 200 patients were treated with coil embolization between January 2000 and April 2008. Parent artery variations at each location were classified as: AcoA: A1 aplasia versus hypoplasia versus symmetrical size; PcoA: foetal origin versus medium versus small size, BA: cranial versus caudal versus asymmetrical fusion. The incidence of aneurysms and difference between recurrence rates for each group were recorded on follow-up. Results: AcoA, PcoA, and BA aneurysms were more often associated with embryonically earlier vessel wall dispositions (A1 aplasia, foetal PcoA, asymmetrical fusion). Two of these variations were also associated with aneurysm recurrence following coil embolization: asymmetrical A1 segment (p = 0.01), and asymmetrical BA tip (p = 0.02). Conclusions: AcoA, PcoA, and BA tip aneurysms tend to occur more often in anatomically variant parent artery dispositions, some of which are related to aneurysm recurrence following coil embolization. This may relate to a more fragile vessel disposition as it is not fully matured or to altered haemodynamics secondary to the anatomical variations.

Laser induced fluorescence spectroscopy in atomic beams of radioactive nuclides

International Nuclear Information System (INIS)

Rebel, H.; Schatz, G.

1982-01-01

Measurements of the resonant scattering of light from CW tunable dye lasers, by a well collimated atomic beam, enable hyperfine splittings and optical isotope shifts to be determined with high precision and high sensitivity. Recent off-line atomic beam experiments with minute samples, comprising measurements with stable and unstable Ba, Ca and Pb isotopes are reviewed. The experimental methods and the analysis of the data are discussed. Information on the variation of the rms charge radii and on electromagnetic moments of nuclei in long isotopic chains is presented. (orig.) [de

Incidence of hepatotropic viruses in biliary atresia.

Science.gov (United States)

Rauschenfels, Stefan; Krassmann, Miriam; Al-Masri, Ahmed N; Verhagen, Willem; Leonhardt, Johannes; Kuebler, Joachim F; Petersen, Claus

2009-04-01

Biliary atresia (BA) is the most frequent indication for paediatric liver transplantation. We tested the hypothesis of a viral aetiology of this disease by screening liver samples of a large number of BA patients for the common human hepatotropic viruses. Moreover, we correlated our findings to the expression of Mx protein, which has been shown to be significantly up-regulated during viral infections. Seventy-four liver biopsies (taken during Kasai portoenterostomy) were tested by polymerase chain reaction (PCR) for DNA viruses (herpes simplex virus [HSV], Epstein-Barr virus [EBV], varicella zoster virus [VZV], cytomegalovirus [CMV], adenovirus, parvovirus B19 and polyoma BK) and RNA viruses (enteroviruses, rotavirus and reovirus 3). Mx protein expression was assessed by immunohistochemistry. Virus DNA/RNA was found in less than half of the biopsies (8/74 CMV, 1/74 adenovirus; 21/64 reovirus, 1/64 enterovirus). A limited number presented with double infection. Patients that had detectable viral RNA/DNA in their liver biopsies were significantly older than virus-free patients (P = 0.037). The majority (54/59) of the liver biopsies showed expression of Mx proteins in hepatocytes, bile ducts and epithelium. Our data suggest that the known hepatotropic viruses do not play a major role in the aetiology and progression of BA. Their incidence appears to be, rather, a secondary phenomenon. Nonetheless, the inflammatory response in the livers of BA patients mimics that observed during viral infections.

Ba incorporation in benthic foraminifera

NARCIS (Netherlands)

de Nooijer, L.J.; Brombacher, Anieke; Mewes, A.; Langer, Gerald; Nehrke, G.; Bijma, Jelle; Reichart, G.J.

2017-01-01

Barium (Ba) incorporated in the calcite of many foraminiferal species is proportional to the concentration of Ba in seawater. Since the open ocean concentration of Ba closely follows seawater alkalinity, foraminiferal Ba ∕ Ca can be used to reconstruct the latter. Alternatively, Ba ∕ Ca from

Experimental atomic physics

International Nuclear Information System (INIS)

Sellin, I.A.; Elston, S.B.; Forester, J.P.; Liao, K.H.; Pegg, D.J.; Peterson, R.S.; Thoe, R.S.; Hayden, H.C.; Griffin, P.M.

1976-01-01

The atomic structure and collision phenomena of highly stripped ions in the range Z = 6 to 35 were studied. Charge-transfer and multiple-electron-loss cross sections were determined. Absolute x-ray-production cross sections for incident heavy ions were measured. 10 figures, 1 table

Alpha decay of 114Ba

International Nuclear Information System (INIS)

Mazzocchi, C.; Janas, Z.; Batist, L.; Belleguic, V.; Doering, J.; Kapica, M.; Kirchner, R.; Roeckl, E.; Gierlik, M.; Zylicz, J.; Mahmud, H.; Schmidt, K.; Woods, P.J.

2003-01-01

The neutron-deficient isotope 114 Ba was produced in a fusion evaporation reaction at the GSI On-Line Mass Separator. We measured the α-particle energy of 114 Ba, the half-life of its daughter nucleus 110 Xe, and the α-decay branching ratios for 114 Ba, 110 Xe and 106 Te. (orig.)

Effect of local environment on crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba solid solutions

Energy Technology Data Exchange (ETDEWEB)

Terekhin, M.A. [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Makhov, V.N., E-mail: makhov@sci.lebedev.ru [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Lebedev, A.I.; Sluchinskaya, I.A. [Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

2015-10-15

Spectral and kinetic properties of extrinsic crossluminescence (CL) in SrF{sub 2}:Ba (1%) and CaF{sub 2}:Ba (1%) are compared with those of intrinsic CL in BaF{sub 2} and are analyzed taking into account EXAFS data obtained at the Ba L{sub III} edge and results of first-principles calculations. The CL decay time was revealed to be longer in SrF{sub 2}:Ba and CaF{sub 2}:Ba compared to BaF{sub 2}. This fact contradicts the expected acceleration of luminescence decay which could result from an increased overlap of wave functions in solid solutions due to shortening of the Ba-F distance obtained in both EXAFS measurements and first-principles calculations. This discrepancy is explained by the effect of migration and subsequent non-radiative decay of the Ba (5p) core holes in BaF{sub 2} and by decreasing of the probability of optical transitions between Ba (5p) states and the valence band in SrF{sub 2}:Ba and CaF{sub 2}:Ba predicted by first-principles calculations. - Highlights: • The crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba is slower than in BaF{sub 2}. • Ba{sup 2+} ions substitute for host Ca{sup 2+}(Sr{sup 2+}) ions in the on-center positions. • The nearest Ba-F distances in SrF{sub 2}:Ba and CaF{sub 2}:Ba are shorter than in BaF{sub 2}. • EXAFS data and first-principles calculations of the local structure agree well. • First-principles calculations explain slower luminescence decay in solid solutions.

The Role of the International Atomic Energy Agency in a Response to Nuclear and Radiological Incidents and Emergencies

Energy Technology Data Exchange (ETDEWEB)

Buglova, E.; Baciu, F., E-mail: E.Buglova@iaea.org [International Atomic Energy Agency (IAEA), Department of Nuclear Safety and Security, Wagramer Strasse 5, P.O. Box 100, 1400 Vienna (Austria)

2014-10-15

Full text: The role of the International Atomic Energy Agency (IAEA) in a response to nuclear and radiological incidents and emergencies has been defined and further expanded through the IAEA Statute, the Convention on Early Notification of a Nuclear Accident, the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency, the Convention on Physical Protection of Nuclear Material, IAEA safety standards, relevant decisions by Policy Making Organs of the IAEA, inter-agency agreements and other documents such as the IAEA Action Plan on Nuclear Safety. The IAEA Secretariat fulfils its roles through the Agency's Incident and Emergency System (IES) and the Incident and Emergency Centre (IEC). The IEC is the global focal point for international preparedness and response to nuclear and radiological safety or security related incidents, emergencies, threats or events of media interest and for coordination of International assistance. During a response the IEC performs and facilitates for Member States many specific functions which include: prompt notification; official information exchange; assessment of potential consequences; prognosis of emergency progression; provision, facilitation and coordination of International assistance; provision of timely, accurate and easily understandable public information; coordination of inter-agency response at the International level. Through officially designated contact points of Member States the IEC is able to communicate at any time with national authorities to ensure the prompt and successful sharing of information and resources. The IEC routinely performs internal exercising of all aspects of the IAEA response and in cooperation with Member States, the IAEA organizes and facilitates the conduct of large scale international exercises to practice cooperation and coordination. This presentation outlines in detail the specific functions of the IAEA IEC during a response. (author)

Ba 5s photoionization in the region of the second Cooper minimum

International Nuclear Information System (INIS)

Whitfield, S B; Wehlitz, R; Dolmatov, V K

2011-01-01

We investigate the 5s angular distribution parameter and partial photoionization cross section of atomic Ba in the region of the second Cooper minimum covering a photon energy region from 120 to 260 eV. We observe a strong drop in the Ba 5s β value from 2.0, reaching a minimum of 1.57 ± 0.07 at a photon energy of 150 eV. The β value then slowly rises back towards its nominal value of 2.0 at photon energies beyond the minimum. Our measured 5s partial cross section also shows a pronounced dip around 170 eV due to interchannel coupling with the Ba 4d photoelectrons. After combining our measurements with previous experimental values at lower photon energies, we obtain a consistent data set spanning the photon energy range prior to the onset of the partial cross section maximum and through the cross section minimum. We also calculate the 5s partial cross section under several different levels of approximation. We find that the generalized random-phase approximation with exchange calculation models the shape and position of the combined experimental cross section data set rather well after incorporating experimental ionization energies and a shift in the photon energy scale.

High-temperature thermoelectric properties of La-doped BaSnO3 ceramics

International Nuclear Information System (INIS)

Yasukawa, Masahiro; Kono, Toshio; Ueda, Kazushige; Yanagi, Hiroshi; Hosono, Hideo

2010-01-01

To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO 3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba 1-x La x SnO 3 (x = 0.00-0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93-97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x = 0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373-1073 K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x = 0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S 2 σ increased drastically with La doping, and reached a maximum for x = 0.01 with values of 0.8 x 10 -4 W m -1 K -2 at 373 K to 2.8 x 10 -4 W m -1 K -2 at 1073 K.

Structure and stability of BaTiSi₂O₇.

Science.gov (United States)

Viani, Alberto; Palermo, Andrea; Zanardi, Stefano; Demitri, Nicola; Petrícek, Václav; Varini, Federico; Belluso, Elena; Ståhl, Kenny; Gualtieri, Alessandro Francesco

2015-04-01

Due to their optical, photo-luminescence (PL), and afterglow properties, barium titanosilicates are compounds of great interest for functional materials and light-emitting devices. Among them, BaTiSi2O7 (BTS2) is certainly one of the most intriguing; it displays peculiar properties (e.g. PL orange emission) whose exhaustive explanation has been hampered to date by the lack of a structure model. In this work, BTS2 and the related compound BaTiSi4O11 (BTS4) were synthesized through conventional solid-state reaction methods. BTS2 invariably shows complex twinning patterns. Thus, its structure solution and Rietveld structure refinement were attempted using synchrotron powder diffraction. BTS2 was found to be an intergrowth of monoclinic and triclinic crystals. The monoclinic phase has the space group P21/n and unit cell a = 7.9836 (3), b = 10.0084 (4), c = 7.4795 (3) Å, and β = 100.321 (3)°, whereas the triclinic phase has the space group P\\bar 1 and unit cell a = 7.99385 (4), b = 10.01017 (5), c = 7.47514 (3) Å, α = 90.084 (8), β = 100.368 (8) and γ = 89.937 (9)°. These lattices can be seen as a distortion of that of tetragonal synthetic β-BaVSi2O7 with Ti in place of V. The structure models obtained from this study confirm the presence of fivefold coordinated Ti atoms in a distorted pyramidal configuration. The proposed solution supports existing theories for the explanation of the PL orange colour in BTS2.

Complementary resistive switching in BaTiO3/NiO bilayer with opposite switching polarities

Science.gov (United States)

Li, Shuo; Wei, Xianhua; Lei, Yao; Yuan, Xincai; Zeng, Huizhong

2016-12-01

Resistive switching behaviors have been investigated in the Au/BaTiO3/NiO/Pt structure by stacking the two elements with different switching types. The conducting atomic force microscope measurements on BaTiO3 thin films and NiO thin films suggest that with the same active resistive switching region, the switching polarities in the two semiconductors are opposite to each other. It is in agreement with the bipolar hysteresis I-V curves with opposite switching polarities for single-layer devices. The bilayer devices show complementary resistive switching (CRS) without electroforming and unipolar resistive switching (URS) after electroforming. The coexistence of CRS and URS is mainly ascribed to the co-effect of electric field and Joule heating mechanisms, indicating that changeable of resistance in this device is dominated by the redistribution of oxygen vacancies in BaTiO3 and the formation, disruption, restoration of conducting filaments in NiO. CRS in bilayer with opposite switching polarities is effective to solve the sneak current without the introduction of any selector elements or an additional metal electrode.

Activation cross section and isomeric cross-section ratio for the (n,2n) reaction on {sup 132,134}Ba

Energy Technology Data Exchange (ETDEWEB)

Luo, Junhua [Hexi Univ., Zhangye (China). School of Physics and Electromechanical Engineering; Hexi Univ., Zhangye (China). Inst. of New Energy; Wu, Chunlei; Jiang, Li [Chinese Academy of Engineering Physics, Mianyang (China). Inst. of Nuclear Physics and Chemistry; Li, Suyuan [Hexi Univ., Zhangye (China). Inst. of New Energy

2017-07-01

Cross sections of the {sup 132}Ba(n,2n){sup 131m,g}Ba and {sup 134}Ba(n,2n){sup 133m,g}Ba reactions and their isomeric cross section ratios σ{sub m}/σ{sub g} have been measured by means of the activation technique at three neutron energies in the range 13-15 MeV. BaCO{sub 3} samples and Nb monitor foils were activated together to determine the reaction cross section and the incident neutron flux. The quasimonoenergetic neutrons beam were produced via the {sup 3}H(d,n){sup 4}He reaction at the Pd-300 Neutron Generator of the Chinese Academy of Engineering Physics (CAEP). The activities induced in the reaction products were measured using high-resolution γ ray spectroscopy. The pure cross section of the ground-state was derived from the absolute cross section of the metastable state and the residual nuclear decay analysis. Cross sections were also evaluated theoretically using the numerical nuclear model code, TALYS-1.8 with different level density options at neutron energies varying from the reaction threshold to 20 MeV. Results are discussed and compared with the corresponding literature.

Accurate determination of the composition of Y-Ba-Cu-O superconductor by spectrophotometry, gravimetry and flame AAS

Energy Technology Data Exchange (ETDEWEB)

Bruneel, E [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281(S3), 9000 Ghent (Belgium); Verbauwhede, D [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281(S3), 9000 Ghent (Belgium); Vyver, D Van de [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281(S3), 9000 Ghent (Belgium); Schaubroeck, J [Departement Industriele Wetenschappen, Hogeschool Gent, Schoonmeerstraat 52 9000 Ghent (Belgium); Hoste, S [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281(S3), 9000 Ghent (Belgium); Driessche, I Van [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281(S3), 9000 Ghent (Belgium)

2005-06-01

A procedure for the accurate analytical determination of yttrium, barium and copper in an YBa{sub 2}Cu{sub 3}O{sub x} superconductor is described. After dissolution of the material the concentration of Y and Cu was spectrophotometrically determined as an Y-Arsenazo III and a Cu-Nitroso-R-salt complex, respectively. Ba was determined either gravimetrically as BaCrO{sub 4}, after precipitation using a K{sub 2}CrO{sub 4} solution or using flame atomic absorption spectroscopy (AAS). An accuracy better than 0.7% and a coefficient of variation better then 1.2% are obtained. It is illustrated that this analytical procedure can be used to determine the composition of a bulk superconducting YBa{sub 2}Cu{sub 3}O{sub x} sample. For determination of Ba in thin films we suggest the use of flame AAS, with an accuracy of 0.03% and a coefficient of variation of 1.7%.

Studies on strain relaxation of La{sub 0.5}Ba{sub 0.5}MnO{sub 3} film by normal and grazing incidence X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Haiou [Hangzhou Dianzi University, Institute of Materials Physics, Hangzhou (China); Tan, Weishi [Hunan City University, College of Communication and Electronic Engineering, Yiyang (China); Nanjing University of Science and Technology, Key Laboratory of Soft Chemistry and Functional Materials, Department of Applied Physics, Ministry of Education, Nanjing (China); Liu, Hao [Suzhou Institute of Industrial Technology, Department of Electronic and Communication Engineering, Suzhou (China); Cao, Mengxiong; Wang, Xingyu; Ma, Chunlin [Nanjing University of Science and Technology, Key Laboratory of Soft Chemistry and Functional Materials, Department of Applied Physics, Ministry of Education, Nanjing (China); Jia, Quanjie [The Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)

2017-03-15

Perovskite manganite La{sub 0.5}Ba{sub 0.5}MnO{sub 3} (LBMO) films were deposited on (001)-oriented single-crystal SrTiO{sub 3} (STO) substrates by pulsed laser deposition. High-resolution X-ray diffraction and grazing incidence X-ray diffraction techniques were applied to characterize the crystal structure and lattice strain of LBMO films. The in-plane and out-of-plane growth orientations of LBMO films with respect to substrate surface have been studied. The epitaxial orientation relationship LBMO (001) [100] //STO (001) [100] exists at the LBMO/STO interface. The lattice strain of LBMO film begins to relax with the thickness of LBMO film up to 12 nm. When the thickness is further increased up to 43 nm, the film is in fully strain-relaxed state. Jahn-Teller strain plays an important role in LBMO/STO system. The mechanism for strain relaxation is in accordance with that of tetragonal distortion. (orig.)

The incidence of leukemia, lymphoma, and multiple myeloma among atomic bomb survivors: 1950 – 2001

Science.gov (United States)

Hsu, Wan-Ling; Preston, Dale L.; Soda, Midori; Sugiyama, Hiromi; Funamoto, Sachiyo; Kodama, Kazunori; Kimura, Akiro; Kamada, Nanao; Dohy, Hiroo; Tomonaga, Masao; Iwanaga, Masako; Miyazaki, Yasushi; Cullings, Harry M.; Suyama, Akihiko; Ozasa, Kotaro; Shore, Roy E.; Mabuchi, Kiyohiko

2013-01-01

A marked increase in leukemia risks was the first and most striking late effect of radiation exposure seen among the Hiroshima and Nagasaki atomic bomb survivors. This paper presents analyses of radiation effects on leukemia, lymphoma, and multiple myeloma incidence in the Life Span Study cohort of atomic bomb survivors updated 14 years since the last comprehensive report on these malignancies. These analyses make use of tumor- and leukemia-registry-based incidence data on 113,011 cohort members with 3.6 million person-years of follow-up from late 1950 through the end of 2001. In addition to a detailed analysis of the excess risk for all leukemias other than chronic lymphocytic leukemia or adult T-cell leukemia (neither of which appear to be radiation-related), we present results for the major hematopoietic malignancy types: acute lymphoblastic leukemia, chronic lymphocytic leukemia, acute myeloid leukemia, chronic myeloid leukemia, adult T-cell leukemia, Hodgkin and non-Hodgkin lymphoma, and multiple myeloma. Poisson regression methods were used to characterize the shape of the radiation dose response relationship and, to the extent the data allowed, to investigate variation in the excess risks with sex, attained age, exposure age, and time since exposure. In contrast to the previous report that focused on describing excess absolute rates, we considered both excess absolute rate (EAR) and excess relative risk (ERR) models and found that ERR models can often provide equivalent and sometimes more parsimonious descriptions of the excess risk than EAR models. The leukemia results indicated that there was a non-linear dose response for leukemias other than chronic lymphocytic leukemia or adult T-cell leukemia, which varied markedly with time and age at exposure, with much of the evidence for this non-linearity arising from the acute myeloid leukemia risks. Although the leukemia excess risks generally declined with attained age or time since exposure, there was evidence

Epitaxial c-axis oriented BaTiO{sub 3} thin films on SrTiO{sub 3}-buffered Si(001) by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Ngo, Thong Q.; McDaniel, Martin D.; Ekerdt, John G., E-mail: ekerdt@che.utexas.edu [Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Posadas, Agham B.; Demkov, Alexander A. [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Hu, Chengqing; Yu, Edward T. [Department of Electrical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Bruley, John [IBM Research Division, Yorktown Heights, New York 10593 (United States)

2014-02-24

Atomic layer deposition (ALD) of epitaxial c-axis oriented BaTiO{sub 3} (BTO) on Si(001) using a thin (1.6 nm) buffer layer of SrTiO{sub 3} (STO) grown by molecular beam epitaxy is reported. The ALD growth of crystalline BTO films at 225  °C used barium bis(triisopropylcyclopentadienyl), titanium tetraisopropoxide, and water as co-reactants. X-ray diffraction (XRD) reveals a high degree of crystallinity and c-axis orientation of as-deposited BTO films. Crystallinity is improved after vacuum annealing at 600  °C. Two-dimensional XRD confirms the tetragonal structure and orientation of 7–20-nm thick films. The effect of the annealing process on the BTO structure is discussed. A clean STO/Si interface is found using in-situ X-ray photoelectron spectroscopy and confirmed by cross-sectional scanning transmission electron microscopy. The capacitance-voltage characteristics of 7–20 nm-thick BTO films are examined and show an effective dielectric constant of ∼660 for the heterostructure.

Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

Science.gov (United States)

Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

2006-07-01

We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

Directory of Open Access Journals (Sweden)

J. Rogge

2015-07-01

Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

Odd-even parity splittings and octupole correlations in neutron-rich Ba isotopes

Science.gov (United States)

Fu, Y.; Wang, H.; Wang, L.-J.; Yao, J. M.

2018-02-01

The odd-even parity splittings in low-lying parity-doublet states of atomic nuclei with octupole correlations have usually been interpreted as rotational excitations on top of octupole vibration in the language of collective models. In this paper, we report a deep analysis of the odd-even parity splittings in the parity-doublet states of neutron-rich Ba isotopes around neutron number N =88 within a full microscopic framework of beyond-mean-field multireference covariant energy density functional theory. The dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation are taken into account with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We show that the behavior of odd-even parity splittings is governed by the interplay of rotation, quantum tunneling, and shape evolution. Similar to 224Ra, a picture of rotation-induced octupole shape stabilization in the positive-parity states is exhibited in the neutron-rich Ba isotopes.

Effects of guest atomic species on the lattice thermal conductivity of type-I silicon clathrate studied via classical molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Kumagai, Tomohisa, E-mail: kumagai@criepi.denken.or.jp; Nakamura, Kaoru; Yamada, Susumu; Ohnuma, Toshiharu [Materials Science Research Laboratory, Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan)

2016-08-14

The effects of guest atomic species in Si clathrates on the lattice thermal conductivity were studied using classical molecular dynamics calculations. The interaction between a host atom and a guest atom was described by the Morse potential function while that between host atoms was described by the Tersoff potential. The parameters of the potentials were newly determined for this study such that the potential curves obtained from first-principles calculations for the insertion of a guest atom into a Si cage were successfully reproduced. The lattice thermal conductivities were calculated by using the Green-Kubo method. The experimental lattice thermal conductivity of Ba{sub 8}Ga{sub 16}Si{sub 30} can be successfully reproduced using the method. As a result, the lattice thermal conductivities of type-I Si clathrates, M{sub 8}Si{sub 46} (M = Na, Mg, K, Ca Rb, Sr, Cs, or Ba), were obtained. It is found that the lattice thermal conductivities of M{sub 8}Si{sub 46}, where M is IIA elements (i.e., M = Mg, Ca, Sr, or Ba) tend to be lower than those of M{sub 8}Si{sub 46}, where M is IA elements (i.e., M = Na, K, Rb, or Cs). Those of {sup m}M{sub 8}Si{sub 46}, where m was artificially modified atomic weight were also obtained. The obtained lattice thermal conductivity can be regarded as a function of a characteristic frequency, f{sub c}. That indicates minimum values around f{sub c}=2-4 THz, which corresponds to the center of the frequencies of the transverse acoustic phonon modes associated with Si cages.

Impact of anatomical variations of the circle of Willis on the incidence of aneurysms and their recurrence rate following endovascular treatment.

Science.gov (United States)

Songsaeng, D; Geibprasert, S; Willinsky, R; Tymianski, M; TerBrugge, K G; Krings, T

2010-11-01

To analyse the impact of anatomical variations of the parent arteries on the incidence and recurrence rate following coil embolization of aneurysms of the anterior (AcoA), posterior communicating artery (PcoA) and basilar artery (BA) tip. Two hundred and two (96 AcoA, 67 PcoA, and 29 BA) aneurysms in 200 patients were treated with coil embolization between January 2000 and April 2008. Parent artery variations at each location were classified as: AcoA: A1 aplasia versus hypoplasia versus symmetrical size; PcoA: foetal origin versus medium versus small size, BA: cranial versus caudal versus asymmetrical fusion. The incidence of aneurysms and difference between recurrence rates for each group were recorded on follow-up. AcoA, PcoA, and BA aneurysms were more often associated with embryonically earlier vessel wall dispositions (A1 aplasia, foetal PcoA, asymmetrical fusion). Two of these variations were also associated with aneurysm recurrence following coil embolization: asymmetrical A1 segment (p=0.01), and asymmetrical BA tip (p=0.02). AcoA, PcoA, and BA tip aneurysms tend to occur more often in anatomically variant parent artery dispositions, some of which are related to aneurysm recurrence following coil embolization. This may relate to a more fragile vessel disposition as it is not fully matured or to altered haemodynamics secondary to the anatomical variations. Copyright © 2010 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

NO and NO{sub 2} adsorption on subsurface doped MgO (100) and BaO (100) surfaces. A density functional study

Energy Technology Data Exchange (ETDEWEB)

Añez, Rafael, E-mail: ranez@ivic.gob.ve [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas (Venezuela, Bolivarian Republic of); Sierraalta, Aníbal [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas (Venezuela, Bolivarian Republic of); Soto, Lenin J. Díaz [Pontifícia Universidade Católica do Rio de Janeiro, Departamento de Física, 22451-900 Rio de Janeiro, RJ (Brazil); Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT Bloco A sala 412, Rio de Janeiro, RJ 21949-900 (Brazil)

2017-05-15

Highlights: • Subsurface doped BaO(100) and MgO(100) surfaces. • NO and NO{sub 2} adsorption on doped BaO(100) and MgO(100) surfaces. • Surface distortion produced by the doped improves the interaction with the surface. • NO and NO{sub 2} adsorption energies displayed good correlation with the transferred charge. - Abstract: A periodic DFT approach was used to study the energetic, electronic and structural changes produced by the V, Fe and Ni sub layer doped of the MgO (100) and BaO (100) surfaces and the effect of these changes over the adsorption of NO and NO{sub 2}. Results indicate that the higher capacity of donating charge of the transition metal atoms improves the ability of the surfaces to transfer charge to the molecules. The charge transferred goes to NO and NO{sub 2} antibonding orbitals which makes them more reactive hence the interaction becomes stronger. A good lineal correlation between the charge transferred and the calculated adsorption energy was found, that is, as the charge transferred increases the adsorption energy increases. The interaction between the NO or NO{sub 2} molecule on doped surfaces not only depends of the charge transferred, surface structural changes produced by the doping with transition metal atoms increase the adsorption energy specially on the BaO (100) surface where the surface structural changes were more noticeable. Calculated stretching frequency of a NO in a η{sup 1} –N configuration indicates that this is the most stable specie found for the adsorption of NO on terraces of the MgO (100) surface around 77 K and that the sub layer Ni doped BaO (100) surface could be a promising material for the decomposition of NO{sub 2}.

Atomic photoelectron-spectroscopy studies using synchrotron radiation

International Nuclear Information System (INIS)

Kobrin, P.H.

1983-02-01

Photoelectron spectroscopy combined with tunable synchrotron radiation has been used to study the photoionization process in several atomic systems. The time structure of the synchrotron radiation source at the Stanford Synchrotron Radiation Laboratory (SSRL) was used to record time-of-flight (TOF) photoelectron spectra of gaseous Cd, Hg, Ne, Ar, Ba, and Mn. The use of two TOF analyzers made possible the measurement of photoelectron angular distributions as well as branching ratios and partial cross sections

Structural and electrical properties of Barium Titanate (BaTiO3 and Neodymium doped BaTiO3 (Ba0.995Nd0.005TiO3

Directory of Open Access Journals (Sweden)

Tuan Sulong Tuan Amirah

2017-01-01

Full Text Available Barium titanate (BaTiO3 and Neodymium (Nd doped BaTiO3 with composition Ba0.995Nd0.005TiO3 were prepared using conventional solid state reaction method to study the dielectric properties of materials. Pure phase samples were found at final heating temperature of 1400°C for overnight. X-ray diffraction analysis reveals the changes in the lattice parameter and unit cell volume of the pure perovskite tetragonal structure with space group (P4mm. Electrical analysis is carried out to investigate the dielectric properties, conductivity behaviour and dielectric loss of BaTiO3 and Ba0.995Nd0.005TiO3. Ba0.995Nd0.005TiO3 have a broaden dielectric peaks with high permittivity of 8000 and reasonably low loss tan δ which is about 0.004 (1 kHz.

Structure and distribution of the Bacillus thuringiensis Cry4Ba toxin in lipid membranes

International Nuclear Information System (INIS)

Puntheeranurak, Theeraporn; Stroh, Cordula; Zhu Rong; Angsuthanasombat, Chanan; Hinterdorfer, Peter

2005-01-01

Bacillus thuringiensis Cry δ-endotoxins cause death of susceptible insect larvae by forming lytic pores in the midgut epithelial cell membranes. The 65 kDa trypsin activated Cry4Ba toxin was previously shown to be capable of permeabilizing liposomes and forming ionic channels in receptor-free planar lipid bilayers. Here, magnetic ACmode (MACmode) atomic force microscopy (AFM) was used to characterize the lateral distribution and the native molecular structure of the Cry4Ba toxin in the membrane. Liposome fusion and the Langmuir-Blodgett technique were employed for supported lipid bilayer preparations. The toxin preferentially inserted in a self-assembled structure, rather than as a single monomeric molecule. In addition, the spontaneous insertion into receptor-free lipid bilayers lead to formation of characteristic pore-like structures with four-fold symmetry, suggesting that tetramers are the preferred oligomerization state of this toxin

DFT study of the polarization behaviors of various distorted barium titanate crystals: The role of atomic displacements

Science.gov (United States)

Mirseraji, Mojtaba; Shahraki, Mehran Gholipour

2018-06-01

A Local Density Approximation (LDA) was employed to investigate the influence of applied strains on valence charge distributions, atomic displacements, Tisbnd O (3) bond distances and the total polarizations in barium titanate (BaTiO3). Four types of various strains were imposed on perfect tetragonal BaTiO3 along the a, c, ab and abc axial directions. Electromechanical properties of BaTiO3 were evaluated in LDA framework and a good agreement with previous results was achieved. The results show that, in the cases of a, ab strains, the values of polarization are almost constant in negative strains and increased by gradual increasing of the positive strains after a sudden enhancement at about +0.1% strain. In the case of c-strain, axial oxygen and Ti atoms underwent the highest displacements and the polarization linearly increased by applied strain. The case of abc-strain, represent the both types of features. In negative abc-strain show a similar polarization behavior like c-strain case and in positive region, polarization behavior is the same as a- and ab-strain cases. In the abc-strains of -0.3% and +0.1%, an abrupt jump in total polarization curve and a small change, are observed due to abnormal atomic displacements. In the most cases a direct relation between polarization and Tisbnd O (3) bond distance was also beheld. Finally, the effects of valence charge distributions on the atomic displacements and total polarizations are studied. It is found that there is a direct relation between polarization and Valence Charge Asymmetry of 3d -orbitals.

Chalcogenidosilicates: Ba/sub 2/SiTe/sub 4/ and Ba/sub 2/SiSe/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Brinkmann, C; Eisenmann, B; Schaefer, H [Technische Hochschule Darmstadt (Germany, F.R.). Fachbereich Anorganische Chemie und Kernchemie

1985-05-01

The new compounds Ba/sub 2/SiSe/sub 4/ and Ba/sub 2/SiTe/sub 4/ crystallize in the monoclinic system, space group: P2/sub 1//m (No. 11) with the lattice constants Ba/sub 2/SiSe/sub 4/: a = 918.4(5) pm, b = 703.3(3) pm, c = 687.2(3) pm, ..beta.. = 109.2(1)/sup 0/, Ba/sub 2/SiTe/sub 4/: a = 965.0(5) pm, b = 762.6(3) pm, c = 746.6(3) pm, ..beta.. = 108.9(1)/sup 0/. Both compounds are isotypic to the Sr/sub 2/GeS/sub 4/ structure. Ba/sub 2/SiTe/sub 4/ is the first o-telluridosilicate with discrete SiTe/sub 4//sup 4 -/ anions.

Iron phosphate glasses: Bulk properties and atomic scale structure

Energy Technology Data Exchange (ETDEWEB)

Joseph, Kitheri; Stennett, Martin C.; Hyatt, Neil C.; Asuvathraman, R.; Dube, Charu L.; Gandy, Amy S.; Govindan Kutty, K. V.; Jolley, Kenny; Vasudeva Rao, P. R.; Smith, Roger

2017-10-01

Bulk properties such as glass transition temperature, density and thermal expansion of iron phosphate glass compositions, with replacement of Cs by Ba, are investigated as a surrogate for the transmutation of 137Cs to 137Ba, relevant to the immobilisation of Cs in glass. These studies are required to establish the appropriate incorporation rate of 137Cs in iron phosphate glass. Density and glass transition temperature increases with the addition of BaO indicating the shrinkage and reticulation of the iron phosphate glass network. The average thermal expansion coefficient reduces from 19.8 × 10-6 K-1 to 13.4 × 10-6 K-1, when 25 wt. % of Cs2O was replaced by 25 wt. % of BaO in caesium loaded iron phosphate glass. In addition to the above bulk properties, the role of Ba as a network modifier in the structure of iron phosphate glass is examined using various spectroscopic techniques. The FeII content and average coordination number of iron in the glass network was estimated using Mössbauer spectroscopy. The FeII content in the un-doped iron phosphate glass and barium doped iron phosphate glasses was 20, 21 and 22 ± 1% respectively and the average Fe coordination varied from 5.3 ± 0.2 to 5.7 ± 0.2 with increasing Ba content. The atomic scale structure was further probed by Fe K-edge X-ray absorption spectroscopy. The average coordination number provided by extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge structure was in good agreement with that given by the Mössbauer data.

Relativistic calculations of the fine-structure intervals of the ns2np2P terms and the ionization energies of the Ca-, Sr-and Ba- ions

International Nuclear Information System (INIS)

Wijesundera, W.P.; Vosko, S.H.; Parpia, F.A.

1996-01-01

We report new calculations of the energy differences between the ns 1/2 2 np 1/2 and ns 1/2 2 np 3/2 levels of the Ca - , Sr - and Ba - ions; here n 4, 5 and 6 for Ca - , Sr - and Ba - , respectively. The electron affinities of Ca, Ba and Sr have also been calculated. All estimates were obtained by performing a series of multiconfiguration Dirac-Fock calculations for the neutral atoms and their anions. Correlations among valence electrons in both the ground and excited states were included in these calculations. Our estimate of the fine structure of the ground state of Sr - is in good agreement with recent measurements. Our estimates of the electron affinities of Ca, Sr and Ba are in reasonable agreement with experiment. (author)

A new oxytelluride: Perovskite and CsCl intergrowth in Ba{sub 3}Yb{sub 2}O{sub 5}Te

Energy Technology Data Exchange (ETDEWEB)

Whalen, J.B., E-mail: icatchsnook@yahoo.com [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Specialized Crystal Processing, Inc., 400 Capital Circle SE, Suite 18227, Tallahassee, FL 32301-3839 (United States); Besara, T. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Vasquez, R.; Herrera, F. [The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Sun, J. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Ramirez, D. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Specialized Crystal Processing, Inc., 400 Capital Circle SE, Suite 18227, Tallahassee, FL 32301-3839 (United States); Stillwell, R.L. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); and others

2013-07-15

The new oxytelluride Ba{sub 3}Yb{sub 2}O{sub 5}Te was obtained from an alkaline earth flux. Ba{sub 3}Yb{sub 2}O{sub 5}Te crystallizes in the tetragonal space group P4/mmm (#123), with a=4.3615(3) Å and c=11.7596(11) Å, Z=1. The structure combines two distinct building blocks, a Ba{sub 2}Yb{sub 2}O{sub 5} perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5 K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden–Popper phases, where the NaCl-type layer has been replaced by the CsCl-type layer. The two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure. - Graphical abstract: Optical images of Ba{sub 3}Yb{sub 2}O{sub 5}Te in transmission (left) and reflected (right) light, with atomic unit cell overlay. - Highlights: • Single crystal synthesis and characterization of a new phase, Ba{sub 3}Yb{sub 2}O{sub 5}Te. • The structure features the BaTe high pressure polymorph intergrowth. • Magnetic susceptibility measurements show short range 2 dimensional ordering. • Heat capacity measurements show a feature at the magnetic ordering temperature. • Optical reflectivity measurements show a {sup 2}F{sub 7/2}→{sup 2}F{sub 5/2} absorption at 976 nm.

The BaBar Mini

International Nuclear Information System (INIS)

Brown, David N.

2003-01-01

BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

The BaBar mini

International Nuclear Information System (INIS)

Brown, David N.; BaBar Collaboration

2003-01-01

BaBar has recently deployed a new event data format referred to as the Mini. The mini uses efficient packing and aggressive noise suppression to represent the average reconstructed BaBar event in under 7 KBytes. The Mini packs detector information into simple transient data objects, which are then aggregated into roughly 10 composite persistent objects per event. The Mini currently uses Objectivity persistence, and it is being ported to use Root persistence. The Mini contains enough information to support detailed detector studies, while remaining small and fast enough to be used directly in physics analysis. Mini output is customizable, allowing users to both truncate unnecessary content or add content, depending on their needs. The Mini has now replaced three older formats as the primary output of BaBar event reconstruction. A reduced form of the Mini will soon replace the physics analysis format as well, giving BaBar a single, flexible event data format covering all its needs

An interface between the nuclear physics and the atomic physics; how to measure nuclear times observing atomic transitions

International Nuclear Information System (INIS)

Pinho, A.G. de

1985-01-01

Recent observations are related in which processes resulting from the ionization in ion-atom collisions are observed in coincidence with nuclear processes (where the incidence ion nucleus hits the target atom nucleus). The delay introduced by the nuclear reaction contaminates the results of the atomic collision and manifest itself either in the X rays (positrons) emitted in the joined atom system or in the X rays (Auger electrons) emitted by separeted atoms, after the collision. Both effects serve to obtain information on the reaction times (in general much less then 10 -16 sec). Following this line, other experimental possibilities are discussed. (L.C.) [pt

Leukemia incidence among individuals exposed in utero, children of atomic bomb survivors, and their controls; Hiroshima and Nagasaki, 1945-79

International Nuclear Information System (INIS)

Ishimaru, Toranosuke; Ichimaru, Michito; Mikami, Motoko.

1982-03-01

The incidence of leukemia has been analyzed in relation to the fetal dose of individuals exposed in utero, and the parental gonadal dose of individuals born to atomic bomb survivors and controls in the two fixed RERF cohorts. Among 3,636 in utero exposed children and controls, 3 leukemia cases have been identified through 1979. No excess risk of leukemia for in utero exposed children is apparent. For children born to exposed parents and controls, 36 leukemia cases have been identified in the years 1946-79 among 50,689 study subjects where the parental gonadal dose is available. Again, no excess risk of leukemia exists. (author)

Atomic bomb cataracts

International Nuclear Information System (INIS)

Shiraeda, Kanji

1992-01-01

Eye disturbance caused by atomic bomb radiation can be divided into three groups: direct injury immediately after exposure, eye lesions associated with radiation syndrome, and delayed disturbance. The crystalline lens of the eye is the most radiosensitive. Atomic bomb cataract has been investigated in a number of studies. The first section of this chapter discusses radiation cataract in terms of the incidence and characteristics. The second section deals with atomic bomb cataract, which can be diagnosed based on the four criteria: (1) opacity of the crystalline lens, (2) a history of proximal exposure, (3) lack of eye disease complicating cataract, and (4) non-exposure to radiation other than atomic bombing. The prevalence of cataract and severity of opacity are found to correlate with exposure doses and age at the time of exposure. Furthermore, it is found to correlate with distance from the hypocenter, the condition of shielding, epilation, and the presence or absence or degree of radiation syndrome. (N.K.)

Aplastic anemia and related disorders in atomic bomb survivors

International Nuclear Information System (INIS)

Ichimaru, Michito; Tomonaga, Yu; Matsunaga, Masako; Sadamori, Naoki; Ishimaru, Toranosuke.

1978-01-01

Whether the incidence of aplastic anemia significantly increases due to the later effect of atomic-bomb radiation was studied. After the data of aplastic anemia which occurred within 1950 - 1973 were evaluated and the diagnoses of the cases were certified, the incidence of aplastic anemia per 109,000 inhabitants of the cities of Hiroshima and Nagasaki was calculated and compared according to the dose of atomic-bomb radiation. There was no increase in the incidence according to an increase in radiation dose, and there was no fact that aplastic anemia increased in a certain period either. Most of the atomic-bomb survivors who were close to the epicenter and were clinically diagnosed as aplastic anemia had leukemia lesion or myeloid proliferating lesion, and it is likely to be that pathological changes resembling aplastic anemia may appear in a certain phase of myeloid proliferation or as a phenotype of myeloid proliferation. An evaluation was made on cases of aplastic anemia of other groups, but the doses of atomic-bomb radiation which they received were not so much to give effect on the bone marrow except only two cases. (Ueda, J.)

Leukemia in atomic bomb survivors. 1. General observations. Leukemia in survivors of atomic bombing. Cytologic and biochemical studies on the granulocytes in early leukemia among atomic bomb survivors. Leukemogenic effects of ionizing radiation on atomic bomb survivors in Hiroshima City

Energy Technology Data Exchange (ETDEWEB)

Lange, R D; Moloney, W C; Yamawaki, Tokuso; Kastenbaum, M A

1959-01-01

This document contains 4 separate reports on leukemia in survivals of the atomic explosions in Hiroshima and Nagasaki. In the first report, observations on seventy-five established cases of leukemia occurring in people exposed to atomic bomb radiation are presented. These data indicate a great increase in the incidence of leukemia among atomic bomb survivors due to a single massive exposure to ionizing radiation. The leukemogenic effects of radiation are manifested equally in both sexes and at all age levels represented in this series. The striking preponderance of chronic myelogenous leukemia compared to chronic lymphatic leukemia has been noted in exposed individuals but it is pointed out that chronic lymphatic leukemia is comparatively rare among the Japanese. Cases of leukemia are still appearing in atomic bomb survivors. However, since 1950 there has been a steady decline in the number of cases. The second report consists of a review of all cases of leukemia referred to the ABCC from 1948 to April 1952, a total of 75 cases. In the third report, hematological and biochemical findings in separated leukocytes of four cases of preclinical myelogenous leukemia developing in atomic bomb survivors are described. The incidence of leukemia among survivors in Hiroshima is the topic of the fourth report. 38 references, 8 figures, 10 tables.

Electrical properties of (1 0 0)-predominant BaTiO3 films derived from alkoxide solutions of two concentrations

International Nuclear Information System (INIS)

Guo Yiping; Suzuki, Kazuyuki; Nishizawa, Kaori; Miki, Takeshi; Kato, Kazumi

2006-01-01

Lead-free piezoelectric films with thickness larger than 1 μm integrated on silicon substrates have been receiving considerable attention because of environmental concerns and their potential applications in microelectromechanical systems. We demonstrate that, by chemical solution deposition, it is possible to process (1 0 0)-predominant 1 μm BaTiO 3 films on LaNiO 3 /Pt/TiO x /SiO 2 /Si substrates using thinner high-crystallinity columnar BaTiO 3 films as buffer layers. We point out that this kind of buffer layer prepared with a lower concentration solution on the surface of an LaNiO 3 /Pt electrode is effective in enhancing the crystallinity and orientation degree of final BaTiO 3 films prepared with a higher concentration solution. The 1 μm BaTiO 3 films show good dielectric and insulating characteristics against an applied field, and the conduction current shows Schottky emission behavior at modest voltage and space-charge-limited behavior at higher voltage. We also demonstrate that the (1 0 0)-predominant 1 μm BaTiO 3 films have excellent piezoelectric properties: piezoelectric coefficients d 33 higher than 50 pm/V have been determined for the bare films using atomic force microscopy, which are comparable to those of Pb(Zr,Ti)O 3 films. These results indicate that the (1 0 0)-predominant BaTiO 3 films should be promising candidates for microelectromechanical systems applications

Intermediate Phase Study on YBCO Films Coated by Precursor Solutions With F/Ba Atomic Ratio of 2

DEFF Research Database (Denmark)

Wu, W.; Feng, F.; Zhao, Y.

2016-01-01

In the chemical solution deposition process of YBCO superconducting films, fluorine is widely regarded to be of significant importance in avoiding the formation of BaCO3, which hinders the growth of high-quality YBCO films. On the other hand, great efforts have been made to decrease the fluorine......) could be routinely obtained on lanthanum aluminate single-crystal substrates....

Back-contacted BaSi

NARCIS (Netherlands)

Vismara, R.; Isabella, O.; Zeman, M.

2017-01-01

We present the optical investigation of a novel back-contacted architecture for solar cells based on a thin barium (di)silicide (BaSi₂) absorber. First, through the analysis of absorption limits of different semiconducting materials, we show the potential of BaSi₂ for

Titanium magnetic polarization at the Fe/BaTiO3 interfaces: An effect of ferroelectric polarization discontinuity

Science.gov (United States)

Paul, Amitesh; Zheng, Jian-Guo; Aoki, Toshihiro

2017-10-01

The exotic magnetic phenomena and the associated functionalities have attracted extensive scientific interest in fundamental physics and cater to the purpose of the novel material search. In this article, with a combination of the electron energy-loss spectroscopy and the X-ray absorption spectroscopy, we have investigated the interfacial Fe atoms and the induced ferromagnetic moment of Ti atoms in Fe/BaTiO3 (BTO) heterostructures. The samples were grown with two different BTO thicknesses, thus resulting in two different states of distorted oxygen environments or different electrostatic potentials. We demonstrate that in these systems, the electronic and magnetic proximity effects remain coupled as the ferroelectric polar discontinuity is held responsible for an induced transfer of the interface electrons. These electrons migrate from the Fe2+ layers to the Ti(4+)-δ layers with the hybridization via O-2p oxide orbitals into Ti orbitals to screen the ferroelectric polarization. These findings, in charge neutral BaO-TiO2 and FeO layers or nonpolar/nopolar interface, essentially underline the central role of the covalent bonding in defining the spin-electronic properties.

Hexagonal perovskites with cationic vacancies. 17. Structure determination on Ba/sub 9/Nb/sub 6/Wvacant/sub 2/O/sub 27/ - the first stacking polytype of a rhombohedral 27 L-type

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Treiber, U [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-03-01

The hexagonal stacking polytype of rhombohedral 27 L-type, Ba/sub 9/Nb/sub 6/Wvacant/sub 2/O/sub 27/, crystallizes in the space group R3m with the sequence (4)1(3)1 = (hhccchhcc)/sub 3/ and three formula units for the trigonal setting. The refined, intensity, related, R'-value is 9.7%. The octahedral net consists of blocks of three face connected octahedra which are linked to each other alternately through one or two octahedra connected exclusively by common vertices. The cationic vacancies are located in the centers of the groups of three octahedra. With this distribution direct contact between occupied face-sharing octahedra is avoided. The niobium and tungsten atoms are distributed statistically between the remaining octahedral holes. In the blocks of three octahedra they are displaced by approximately 0.29 A from their ideal positions in the direction of the central void. The Ba atoms neighbouring a vacancy (all in hexagonal packed BaO/sub 3/ sheets) are dislocated in the direction of the void, while the cubic packed BaO/sub 3/ sheets maintain nearly regular form.

Facile solution-precipitation assisted synthesis and luminescence property of greenish-yellow emitting Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Ji, Haipeng [School of Materials Science and Technology, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Huang, Zhaohui, E-mail: huang118@cugb.edu.cn [School of Materials Science and Technology, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Xia, Zhiguo, E-mail: xiazg@ustb.edu.cn [The Beijing Municipal Key Laboratory of New Energy Materials and Technologies, School of Materials Sciences and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Xie, Yao [School of Materials Science and Technology, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083 (China); Molokeev, Maxim S. [Laboratory of Crystal Physics, Kirensky Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Department of Physics, Far Eastern State Transport University, Khabarovsk 680021 (Russian Federation); Atuchin, Victor V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Functional Electronics Laboratory, Tomsk State University, Tomsk 634050 (Russian Federation); Laboratory of Semiconductor and Dielectric Materials, Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

2016-03-15

Highlights: • Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor was prepared by the solution-precipitation assisted route. • The phosphors have satisfactory smooth grain surface and particle size. • It shows greenish-yellow color emission (maximum at 540 nm) upon blue light excitation. • Eu{sup 2+} is coordinated with isolated oxygen atoms and those from PO{sub 4} polyhedra. - Abstract: Greenish-yellow emitting microcrystalline Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphor was successfully prepared by a solution-precipitation assisted high temperature reaction method. Phase structure, morphology and/or luminescence properties of the precursor and the as-prepared phosphors were characterized. The phase-pure Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} phosphors were obtained with smooth grain surface and particle size of 2–8 μm. Ca{sub 6}Ba(PO{sub 4}){sub 4}O:Eu{sup 2+} exhibits bright greenish-yellow color emission with its maximum at 540 nm upon UV-blue light excitation. The maximum position of the broad emission band is independent on the calcination temperature. The emission intensity increases with increasing calcination temperature due to improved crystallinity. Besides, the presence of two Eu{sup 2+} emission centers in the Ca{sub 6}Ba(PO{sub 4}){sub 4}O crystal lattice was confirmed and the coordination effects are considered concerning the roles of isolated O atoms and those from the PO{sub 4} tetrahedra.

First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.

Science.gov (United States)

Bandura, Andrei V; Evarestov, Robert A

2012-07-05

The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. Copyright © 2012 Wiley Periodicals, Inc.

Octupole correlations in neutron-rich {sup 143,145}Ba and a type of superdeformed band in {sup 145}Ba

Energy Technology Data Exchange (ETDEWEB)

Zhu, S.J.; Wang, M.G.; Long, G.L.; Zhu, L.Y.; Gan, C.Y.; Yang, L.M.; Sakhaee, M.; Li, M.; Deng, J.K. [Physics Department, Tsinghua University, Beijing 100084, Peoples Republic of (China); Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.; Jones, E.F.; Hwang, J.K.; Zhang, X.Q.; Gore, P.M.; Peker, L.K.; Drafta, G.; Babu, B.R.; Deng, J.K.; Ginter, T.N.; Beyer, C.J.; Kormicki, J.; Ter-Akopian, G.M.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhu, S.J.; Ter-Akopian, G.M.; Daniel, A.V. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Ma, W.C. [Physics Department, Mississippi State University, Mississippi 39762 (United States); Cole, J.D.; Aryaeinejad, R.; Drigert, M.W. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States); Rasmussen, J.O.; Asztalos, S.; Lee, I.Y.; Macchiavelli, A.O.; Chu, S.Y.; Gregorich, K.E.; Mohar, M.F. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russia); Donangelo, R. [Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RG (Brazil); Stoyer, M.A.; Lougheed, R.W.; Moody, K.J.; Wild, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Prussin, S.G. [Nuclear Engineering Department, University of California at Berkeley, Berkeley, California 94720 (United States); Kliman, J. [Institute of Physics, SASc, Dubravskacesta 9, 84228 Bratislava (Slovakia); Griffin, H.C. [University of Michigan, Ann Arbor, Michigan 48104 (United States)

1999-11-01

High spin states in neutron-rich odd-{ital Z} {sup 143,145}Ba nuclei have been investigated from the study of prompt {gamma} rays in the spontaneous fission of {sup 252}Cf by using {gamma}-{gamma}- and {gamma}-{gamma}-{gamma}- coincidence techniques. Alternating parity bands are identified for the first time in {sup 145}Ba and extended in {sup 143}Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in {sup 145}Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in {sup 143}Ba and in {sup 145}Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in {sup 145}Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s={minus}i doublets in {sup 143}Ba. {copyright} {ital 1999} {ital The American Physical Society}

Topotactic reduction as a route to new close-packed anion deficient perovskites: structure and magnetism of 4H-BaMnO(2+x).

Science.gov (United States)

Hadermann, Joke; Abakumov, Artem M; Adkin, Josephine J; Hayward, Michael A

2009-08-05

The anion-deficient perovskite 4H-BaMnO(2+x) has been obtained by a topotactic reduction, with LiH, of the hexagonal perovskite 4H-BaMnO(3-x). The crystal structure of 4H-BaMnO(2+x) was solved using electron diffraction and X-ray powder diffraction and further refined using neutron powder diffraction (S.G. Pnma, a = 10.375(2) A, b = 9.466(2) A, c = 11.276(3) A, at 373 K). The orthorhombic superstructure arises from the ordering of oxygen vacancies within a 4H (chch) stacking of close packed c-type BaO(2.5) and h-type BaO(1.5) layers. The ordering of the oxygen vacancies transforms the Mn(2)O(9) units of face-sharing MnO(6) octahedra into Mn(2)O(7) (two corner-sharing tetrahedra) and Mn(2)O(6) (two edge-sharing tetrahedra) groups. The Mn(2)O(7) and Mn(2)O(6) groups are linked by corner-sharing into a three-dimensional framework. The structures of the BaO(2.5) and BaO(1.5) layers are different from those observed previously in anion-deficient perovskites providing a new type of order pattern of oxygen atoms and vacancies in close packed structures. Magnetization measurements and neutron diffraction data reveal 4H-BaMnO(2+x) adopts an antiferromagnetically ordered state below T(N) approximately 350 K.

Phonon dispersion curves of BCC Ba

International Nuclear Information System (INIS)

Mizuki, J.; Stassis, C.; Zarestky, J.

1985-01-01

Ba, as well as Sr and Ca, is a divalent alkaline earth metal. At room temperature and ambient pressure, the structure of Ba is bcc, whereas that of Sr and Ca is fcc. Under pressure, the bcc phase of Ba transforms to an hcp structure at 55 kbar. Also, at 37 kbar Ba becomes a superconductor with T/sub c/ = 0.06 K. These properties are highly dependent on the position of the d bands relative to the Fermi level. Experimental investigation of the elastic and lattice dynamical properties of these metals has been hindered by difficulties in growing single crystals. However, recently the authors were able to grow several single crystals of bcc Ba of sufficient volume for inelastic neutron scattering experiments. Some of the results are summarized here

Electron diffraction and microscopy study of the structure and microstructure of the hexagonal perovskite Ba3Ti2MnO9

International Nuclear Information System (INIS)

Maunders, C.

2007-01-01

This paper reports a structural and microstructural investigation of the hexagonal perovskite Ba 3 Ti 2 MnO 9 using electron microscopy and diffraction. Convergent-beam electron diffraction (CBED) revealed the structure has the noncentrosymmetric space group P6 3 mc (186) at room temperature and at ∝ 110 K. Compared with the centrosymmetric parent structure BaTiO 3 , with space group P6 3 /mmc, this represents a break in mirror symmetry normal to the c axis. This implies the Ti and Mn atoms are ordered on alternate octahedral sites along the left angle 0001 right angle direction in Ba 3 Ti 2 MnO 9 . Using high-resolution electron microscopy (HREM), we observed occasional 6H/12R interfaces on (0001) planes, however, no antiphase boundaries were observed, as were seen in Ba 3 Ti 2 RuO 9 . Using powder X-ray Rietveld refinement we have measured the lattice parameters from polycrystalline samples to be a=5.6880±0.0005, c=13.9223±0.0015 Aa at room temperature. (orig.)

Hyperfine structure and isotope shift of the neutron-rich barium isotopes 139-146Ba and 148Ba

International Nuclear Information System (INIS)

Wendt, K.; Ahmad, S.A.; Klempt, W.; Neugart, R.; Otten, E.W.

1988-01-01

The hyperfine structure and isotope shift in the 6s 2 S 1/2 -6p 2 P 3/2 line of Ba II (455.4 nm) have been measured by collinear fast-beam laser spectroscopy for the neutron-rich isotopes 139-146 Ba and 148 Ba. Nuclear moments and mean square charge radii of these isotopes have been recalculated. The isotope shift of the isotope 148 Ba (T 1/2 = 0.64 s) could be studied for the first time, yielding δ 2 > 138,148 = 1.245(3) fm 2 . (orig.)

In situ development of self-reinforced cellulose nanocrystals based thermoplastic elastomers by atom transfer radical polymerization.

Science.gov (United States)

Yu, Juan; Wang, Chunpeng; Wang, Jifu; Chu, Fuxiang

2016-05-05

Recently, the utilization of cellulose nanocrystals (CNCs) as a reinforcing material has received a great attention due to its high elastic modulus. In this article, a novel strategy for the synthesis of self-reinforced CNCs based thermoplastic elastomers (CTPEs) is presented. CNCs were first surface functionalized with an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP). Subsequently, SI-ATRP of methyl methacrylate (MMA) and butyl acrylate (BA) was carried out in the presence of sacrificial initiator to form CTPEs in situ. The CTPEs together with the simple blends of CNCs and linear poly(MMA-co-BA) copolymer (P(MMA-co-BA)) were characterized for comparative study. The results indicated that P(MMA-co-BA) was successfully grafted onto the surface of CNCs and the compatibility between CNCs and the polymer matrix in CTPEs was greatly enhanced. Specially, the CTPEs containing 2.15wt% CNCs increased Tg by 19.2°C and tensile strength by 100% as compared to the linear P(MMA-co-BA). Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced spin polarization of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend and low-lying shape resonance regions

International Nuclear Information System (INIS)

Yuan, J.; Zhang, Z.

1993-01-01

Spin polarizations (SP's) of elastic electron scattering from alkaline-earth-metal atoms in Ramsauer-Townsend (RT) and low-lying shape resonance (SR) regions are calculated using a relativistic method. The detailed SP distributions both with scattering angle and with electron energy are presented via the energy- and angle-dependent surfaces of SP parameters. It is shown that the SP effects of the collisions of electrons with Ca, Sr, and Ba atoms in the RT region are significant in a considerable area on the energy-angle plane and that the spin-orbit interaction is well increased around the low-lying p-wave SR states of Be and Mg and the d-wave SR states of Ca, Sr, and Ba

Analytical dependence of effective atomic number on the elemental composition of matter and radiation energy in the range 10-1000 keV

Science.gov (United States)

Eritenko, A. N.; Tsvetiansky, A. L.; Polev, A. A.

2018-01-01

In the present paper, a universal analytical dependence of effective atomic number on the composition of matter and radiation energy is proposed. This enables one to consider the case of a strong difference in the elemental composition with respect to their atomic numbers over a wide energy range. The contribution of photoelectric absorption and incoherent and coherent scattering during the interaction between radiation and matter is considered. For energy values over 40 keV, the contribution of coherent scattering does not exceed approximately 10% that can be neglected at a further consideration. The effective atomic numbers calculated on the basis of the proposed relationships are compared to the results of calculations based on other methods considered by different authors on the basis of experimental and tabulated data on mass and atomic attenuation coefficients. The examination is carried out for both single-element (e.g., 6C, 14Si, 28Cu, 56Ba, and 82Pb) and multi-element materials. Calculations are performed for W1-xCux alloys (x = 0.35; x = 0.4), PbO, ther moluminescent dosimetry compounds (56Ba, 48Cd, 41Sr, 20Ca, 12Mg, and 11Na), and SO4 in a wide energy range. A case with radiation energy between the K- and L1-absorption edges is considered for 82Pb, 74W, 56Ba, 48Cd, and 38Sr. This enables to substantially simplify the calculation of the atomic number and will be useful in technical and scientific fields related to the interaction between X-ray/gamma radiation and matter.

Interface Control of Ferroelectricity in an SrRuO3 /BaTiO3 /SrRuO3 Capacitor and its Critical Thickness.

Science.gov (United States)

Shin, Yeong Jae; Kim, Yoonkoo; Kang, Sung-Jin; Nahm, Ho-Hyun; Murugavel, Pattukkannu; Kim, Jeong Rae; Cho, Myung Rae; Wang, Lingfei; Yang, Sang Mo; Yoon, Jong-Gul; Chung, Jin-Seok; Kim, Miyoung; Zhou, Hua; Chang, Seo Hyoung; Noh, Tae Won

2017-05-01

The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO 3 /BaTiO 3 /SrRuO 3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO 2 -BaO and SrO-TiO 2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO 2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transportation incidents involving Canadian shipments of radioactive material

International Nuclear Information System (INIS)

Jardine, J.M.

1979-06-01

This paper gives a brief statement of the legislation governing the transportation of radioactive materials in Canada, reviews the types of shipments made in Canada in 1977, and surveys the transportation incidents that have been reported to the Atomic Energy Control Board over the period 1947-1978. Some of the more significant incidents are described in detail. A totAl of 135 incidents occurred from 1947 to 1978, during which time there were 644750 shipments of radioactive material in Canada

Syntheses, crystal structures and characterizations of BaZn(SeO3)2 and BaZn(TeO3)Cl2

International Nuclear Information System (INIS)

Jiang Hailong; Feng Meiling; Mao Jianggao

2006-01-01

Two new barium zinc selenite and tellurite, namely, BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 , have been synthesized by the solid state reaction. The structure of BaZn(SeO 3 ) 2 features double chains of [Zn(SeO 3 ) 2 ] 2- anions composed of four- and eight-member rings which are alternatively along a-axis. The double chains of [Zn 2 (TeO 3 ) 2 Cl 3 ] 3- anions in BaZn(TeO 3 )Cl 2 are formed by Zn 3 Te 3 rings in which each tellurite group connects with three ZnO 3 Cl tetrahedra. BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements. -- Graphical abstract: Two new barium zinc selenite and tellurite, namely, BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 , have been synthesized by solid state reaction. The structure of BaZn(SeO 3 ) 2 features 1D double chains of [Zn(SeO 3 ) 2 ] 2- anions composed of four- and eight-member rings which are alternatively along a-axis. The 1D double chains of [Zn 2 (TeO 3 ) 2 Cl 3 ] 3- anions in BaZn(TeO 3 )Cl 2 are formed by Zn 3 Te 3 rings in which each tellurite group connects with one ZnO 3 Cl and two ZnO 2 Cl 2 tetrahedra. BaZn(SeO 3 ) 2 and BaZn(TeO 3 )Cl 2 are wide bandgap semiconductors based on optical diffuse reflectance spectrum measurements

Electron - atom bremsstrahlung

International Nuclear Information System (INIS)

Kim, L.

1986-01-01

Features of bremsstrahlung radiation from neutral atoms and atoms in hot dense plasmas are studied. Predictions for the distributions of electron-atom bremsstrahlung radiation for both the point-Coulomb potential and screened potentials are obtained using a classical numerical method. Results agree with exact quantum-mechanical partial-wave results for low incident electron energies in both the point-Coulomb and screened potentials. In the screened potential, the asymmetry parameter of a spectrum is reduced from the Coulomb values. The difference increases with decreasing energy and begins to oscillate at very low energies. The scaling properties of bremsstrahlung spectra and energy losses were also studied. It was found that the ratio of the radiative energy loss for positrons to that for electrons obeys a simple scaling law, being expressible fairly accurately as a function only of the quantity T 1 /Z 2 . This scaling is exact in the case of the point-Coulomb potential, both for classical bremsstrahlung and for the nonrelativistic dipole Sommerfeld formula. Bremsstrahlung from atoms in hot dense plasmas were also studied describing the atomic potentials by the temperature-and-density dependent Thomas-Fermi mode. Gaunt factors were obtained with the relativistic partial-wave method for atoms in plasmas of various densities and temperatures

Electrical transport across nanometric SrTiO3 and BaTiO3 barriers in conducting/insulator/conducting junctions

Science.gov (United States)

Navarro, H.; Sirena, M.; González Sutter, J.; Troiani, H. E.; del Corro, P. G.; Granell, P.; Golmar, F.; Haberkorn, N.

2018-01-01

We report the electrical transport properties of conducting/insulator/conducting heterostructures by studying current-voltage IV curves at room temperature. The measurements were obtained on tunnel junctions with different areas (900, 400 and 100 μm2) using a conducting atomic force microscope. Trilayers with GdBa2Cu3O7 (GBCO) as the bottom electrode, SrTiO3 or BaTiO3 (thicknesses between 1.6 and 4 nm) as the insulator barrier, and GBCO or Nb as the top electrode were grown by DC sputtering on (100) SrTiO3 substrates For SrTiO3 and BaTiO3 barriers, asymmetric IV curves at positive and negative polarization can be obtained using electrodes with different work function. In addition, hysteretic IV curves are obtained for BaTiO3 barriers, which can be ascribed to a combined effect of the FE reversal switching polarization and an oxygen vacancy migration. For GBCO/BaTiO3/GBCO heterostructures, the IV curves correspond to that expected for asymmetric interfaces, which indicates that the disorder affects differently the properties at the bottom and top interfaces. Our results show the role of the interface disorder on the electrical transport of conducting/insulator/conduction heterostructures, which is relevant for different applications, going from resistive switching memories (at room temperature) to Josephson junctions (at low temperatures).

Atomic interferometry

International Nuclear Information System (INIS)

Baudon, J.; Robert, J.

2004-01-01

Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation λ = h/(mv), where λ is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

Temperature dependence of the dielectric permittivity of CaF{sub 2}, BaF{sub 2} and Al{sub 2}O{sub 3}: application to the prediction of a temperature-dependent van der Waals surface interaction exerted onto a neighbouring Cs(8P{sub 3/2}) atom

Energy Technology Data Exchange (ETDEWEB)

Passerat de Silans, Thierry; Maurin, Isabelle; Chaves de Souza Segundo, Pedro; Saltiel, Solomon; Gorza, Marie-Pascale; Ducloy, Martial; Bloch, Daniel [Laboratoire de Physique des Lasers, UMR 7538 du CNRS et de l' Universite Paris 13, 99 Avenue JB Clement, Villetaneuse (France); De Sousa Meneses, Domingos; Echegut, Patrick [CNRS, UPR 3079 CEMHTI, 1D Avenue de la Recherche Scientifique, F-45071 Orleans Cedex 2 (France)], E-mail: daniel.bloch@univ-paris13.fr

2009-06-24

The temperature behaviour in the range 22-500 deg. C of the dielectric permittivity in the infrared range is investigated for CaF{sub 2}, BaF{sub 2} and Al{sub 2}O{sub 3} through reflectivity measurements. The dielectric permittivity is retrieved by fitting reflectivity spectra with a model taking into account multiphonon contributions. The results extrapolated from the measurements are applied to predict a temperature-dependent atom-surface van der Waals interaction. We specifically consider as the atom of interest Cs(8P{sub 3/2}), the most relevant virtual couplings of which fall in the range of thermal radiation and are located in the vicinity of the reststrahlen band of fluoride materials.

High spin structure in 130,131Ba

International Nuclear Information System (INIS)

Kaur, Navneet; Kumar, A.; Singh, Amandeep; Kumar, S.; Kaur, Rajbir; Singh, Varinderjit; Behera, B.R.; Singh, K.P.; Singh, G.; Mukherjee, G.; Sharma, H.P.; Kumar, Suresh; Kumar Raju, M.; Madhusudhan Rao, P.V.; Muralithar, S.; Singh, R.P.; Kumar, Rakesh; Madhvan, N.; Bhowmik, R.K.

2014-01-01

High spin states of 130,131 Ba have been investigated via fusion evaporation reactions 122 Sn( 13 C,4n) 131 Ba and 122 Sn( 13 C, 5n) 130 Ba at E beam =65 MeV. The level schemes of 130,131 Ba have been extended by placing several new γ transitions. A few interband transitions connecting two negative-parity bands, which are the experimental fingerprints of signature partners, have been established in 130 Ba. Spin and parity of a side band have been assigned in 131 Ba and this dipole band is proposed to have a three-quasiparticle configuration, νh 11/2 x πh 11/2 x πg 7/2 . The observed band structures and nuclear shape evolution as a function of the angular momentum have been discussed in the light of Total-Routhian-Surface calculations. (orig.)

A comparative study of the Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15

Science.gov (United States)

Tellier, J.; Boullay, Ph.; Manier, M.; Mercurio, D.

2004-06-01

The room temperature structures of the four-layer Aurivillius phase ferroelectrics CaBi 4Ti 4O 15 and BaBi 4Ti 4O 15 are determined by means of single crystal X-ray diffraction. Regarding the CaBi 4Ti 4O 15 phase, in agreement with the tolerance factor, a significant deformation of the perovskite blocks is observed. The rotation system of the octahedra is typical from even layer Aurivillius phases and leads to the use of the space group A2 1am. For the BaBi 4Ti 4O 15 phase, only a weak variation with respect to the F2 mm space group can be suggested from single crystal X-ray diffraction. A significant presence of Ba atoms in the [ M2O 2] slabs is confirmed in agreement with the previous works but specific Ba 2+ and Bi 3+ sites have to be considered due to the large difference in bounding requirement of these cations. Possible origins for the ferroelectric relaxor behavior of the Ba-based compound are discussed in view of the presented structural analyses.

Low temperature epitaxy of Ge-Sb-Te films on BaF{sub 2} (111) by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Thelander, E., E-mail: erik.thelander@iom-leipzig.de; Gerlach, J. W.; Ross, U.; Lotnyk, A.; Rauschenbach, B. [Leibniz-Institut für Oberflächenmodifizierung e.V., Leipzig 04318 (Germany)

2014-12-01

Pulsed laser deposition was employed to deposit epitaxial Ge{sub 2}Sb{sub 2}Te{sub 5}-layers on the (111) plane of BaF{sub 2} single crystal substrates. X-ray diffraction measurements show a process temperature window for epitaxial growth between 85 °C and 295 °C. No crystalline growth is observed for lower temperatures, whereas higher temperatures lead to strong desorption of the film constituents. The films are of hexagonal structure with lattice parameters consistent with existing models. X-ray pole figure measurements reveal that the films grow with one single out-of-plane crystal orientation, but rotational twin domains are present. The out-of-plane epitaxial relationship is determined to be Ge{sub 2}Sb{sub 2}Te{sub 5}(0001) || BaF{sub 2}(111), whereas the in-plane relationship is characterized by two directions, i.e., Ge{sub 2}Sb{sub 2}Te{sub 5} [-12-10] || BaF{sub 2}[1-10] and Ge{sub 2}Sb{sub 2}Te{sub 5}[1-210] || BaF{sub 2}[1-10]. Aberration-corrected high-resolution scanning transmission electron microscopy was used to resolve the local atomic structure and confirm the hexagonal structure of the films.

Generation of H-, H2(v double-prime), and H atoms by H2+ and H3+ ions incident upon barium surfaces

International Nuclear Information System (INIS)

Hiskes, J.R.; Karo, A.M.

1989-01-01

The generation of vibrationally excited molecules by electron excitation collisions and the subsequent generation of negative ions by dissociative attachment to these molecules has become a standard model for volume source operation. These processes have been supplemented recently by the demonstration of atom-surface recombination to form vibrationally excited molecules, and enhanced negative ion formation by protons incident upon barium electrodes. In this paper we consider the additional processes of molecular vibrational excitation generated by recombination of molecular ions on the electrode surfaces, and negative ion formation by vibrationally excited molecules rebounding from low work-function electrodes. 10 refs., 4 figs

Effect of Sr substitution on superconductivity in Hg2(Ba1-ySry)2YCu2O8-d (part2): bond valence sum approach of the hole distribution

OpenAIRE

Toulemonde, P.; Odier, P.; Bordet, P.; Floch, S. Le; Suard, E.

2004-01-01

The effects of Sr substitution on superconductivity, and more particulary the changes induced in the hole doping mechanism, were investigated in Hg2(Ba1-ySry)2YCu2O8-d by a "bond valence sum" analysis with Sr content from y = 0.0 to y = 1.0. A comparison with CuBa2YCu2O7-d and Cu2Ba2YCu2O8 systems suggests a possible explanation of the Tc enhancement from 0 K for y = 0.0 to 42 K for y = 1.0. The charge distribution among atoms of the unit cell was determined from the refined structure, for y ...

Passivation of CdZnTe surfaces by oxidation in low energy atomic oxygen

International Nuclear Information System (INIS)

Chen, H.; Chattopadhyay, K.; Chen, K.; Burger, A.; George, M.A.; Gregory, J.C.; Nag, P.K.; Weimer, J.J.; James, R.B.

1999-01-01

A method of surface passivation of Cd 1-x Zn x Te (CZT) x-ray and gamma ray detectors has been established by using microwave-assisted atomic oxygen bombardment. Detector performance is significantly enhanced due to the reduction of surface leakage current. CZT samples were exposed to an atomic oxygen environment at the University of Alabama in Huntsville close-quote s Thermal Atomic Oxygen Facility. This system generates neutral atomic oxygen species with kinetic energies of 0.1 - 0.2 eV. The surface chemical composition and its morphology modification due to atomic oxygen exposure were studied by x-ray photoelectron spectroscopy and atomic force microscopy and the results were correlated with current-voltage measurements and with room temperature spectral responses to 133 Ba and 241 Am radiation. A reduction of leakage current by about a factor of 2 is reported, together with significant improvement in the gamma-ray line resolution. copyright 1999 American Vacuum Society

Desorption of Cs+ ions with fast incident atomic and molecular ions

International Nuclear Information System (INIS)

Salehpour, M.; Hunt, J.E.; Tou, L.C.; Hedin, A.; Sundqvist, B.

1988-01-01

Preliminary results on desorption yield measurements of secondary Cs + ions, desorbed as a result of the impact of C + , O + , CO + , O 2 + , CO 2 + and C 4 H 9 + incident ions, in the energy range of 950 keV--3.5 MeV are presented. Molecular beams are found to give high yields of secondary Cs + as a result of impact of O 2 + compared to O + incident ions, indicate no ''collective'' molecular effects. 23 refs., 1 fig

Thermal analysis of formation of nano-crystalline BaTiO3 using Ba(NO32 and TiO2

Directory of Open Access Journals (Sweden)

Md. Jawed Ansaree

2015-12-01

Full Text Available The reaction of Ba(NO32 with TiO2 was studied by thermogravimetric (TG and differential scanning calorimetric (DSC techniques up to 1000 °C and in nitrogen atmosphere. It was found that the formation of BaTiO3 takes place above 600 °C and that precursor mixing time and heating rate have no effect on the reaction temperature. BaTiO3 powder was prepared by calcination of Ba(NO32 and TiO2 precursor mixture at 800 °C for 8 h. X-ray diffraction analysis of the synthesized BaTiO3 confirmed the formation of tetragonal phase with lattice parameters a = 3.9950±0.0003 Å and c = 4.0318±0.0004 Å. Thermal analysis of the synthesized BaTiO3 powder showed weight loss within temperature range 40–1000 °C of only 0.40%. This small amount of weight loss was connected with some impurity phase, and identified as BaCO3 using Fourier transform infrared (FTIR technique.

Growth and characterization of acentric BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Szymborska-Małek, Katarzyna; Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland)

2015-05-15

Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO{sub 3}){sub 2} are presented. Raman and IR spectra of polycrystalline BaZr(BO{sub 3}){sub 2} are also reported to facilitate assignment of modes. BaHf(BO{sub 3}){sub 2} borate crystallizes in trigonal system, space group R3c, with lattice parameters: a=5.1540(4) Å, c=33.901(3) Å. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO{sub 6} octahedra and BaO{sub 6} distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO{sub 3}){sub 2} is isostructural with BaZr(BO{sub 3}){sub 2} and the deviations from centrosymmetry is small. - Graphical abstract: Arrangement of BO{sub 3} groups in BaHf(BO{sub 3}){sub 2} along the c direction in one unit cell. Dark and light blue denote different borate groups. - Highlights: • BaHf(BO{sub 3}){sub 2} single crystals were grown. • X-ray diffraction showed that this borate crystallizes in the acentric R3c structure. • Raman and IR spectra were measured for BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}, respectively. • Assignment of modes is proposed.

Glassy and Metastable Crystalline BaTi2O5 by Containerless Processing

Science.gov (United States)

Yoda, Shinichi; Kentei Yu, Yu; Kumar, Vijaya; Kameko, Masashi

Many efforts have been devoted to forming bulk glass from the melt of ferroelectric crystalline materials without adding any network-forming oxides such as SiO2 due to the potential for producing transparent glass ceramics with high dielectric constant and enhanced piezoelectric, pyroelectric and electro-optic use. The containerless processing is an attractive synthesis tech-nique as it can prevent melt contamination, minimize heterogeneous nucleation, and allow melt to achieve deep undercooling for forming metastable and glassy materials. We have fabricated a new ferroelectric materiel BaTi2 O5 [1] as bulk glass from melt by us-ing containerless processing and studied the phase relationship between microstructure and ferroelectric properties of BaTi2 O5 [2]. The structures of glassy and metastable crystalline BaTi2 O5 fabricated by the containerless pro-cessing were comprehensively investigated by combined X-ray and neutron diffractions, XANES analyses and computer simulations [3]. The 3-dimensional atomic structure of glassy BaTi2 O5 (g-BaTi2 O5 ), simulated by Reverse Monte Carlo (RMC) modelling on diffraction data, shows that extremely distorted TiO5 polyhedra interconnected with both corner-and edge-shared oxy-gen, formed a higher packing density structure than that of conventional silicate glass linked with only corner-sharing of SiO4 polyhedra. In addition, XANES measurement reveales that five-coordinated TiO5 polyhedra were formable in the crystallized metastable a-and b-BaTi2 O5 phases. The structure of metastable b-BaTi2 O5 was solved by ab initio calculation, and refined by Rietveld refinement as group Pnma with unit lattices a = 10.23784 ˚, b = 3.92715 ˚, c A A = 10.92757 A ˚. Our results show that the glass-forming ability enhanced by containerless pro-cessing, not by `strong glass former', fabricated new bulk oxide glasses with peculiar structures and properties. The intermediate-range structure of g-BaTi2 O5 and the crystalline structure of

Effects of REM and Ba Additions on the Characteristics of the Third Generation Duplex Stainless Steel

International Nuclear Information System (INIS)

Park, Yong Soo; Kim, Soon Tae

2006-01-01

The third generation super duplex stainless steel having excellent corrosion resistance, embrittlement resistance, castability, weldability and hot workability has been developed. REM and Ba added to the alloy, with larger atomic radius than those of Cr, Mo and W, seem to fill vacancies inside the matrix and around the grain boundaries, retarding formation of brittle σ and χ phases. In addition, fine oxides/ oxy-sulfides of REM and Ba (1∼3 μm in diameter) seem to enhance the retardation effects. The alloys have also shown higher strength and ductility resulting from phase and grain refinements caused by those oxides and oxy-sulfides. Accordingly it is judged that the core technology can provide the method for remarkably suppressing formation of intermetallic phases by adding new alloy elements, and improving a applied to sea water and flue gas desulfurization facility

Stopping atoms with diode lasers

International Nuclear Information System (INIS)

Watts, R.N.; Wieman, C.E.

1986-01-01

The use of light pressure to cool and stop neutral atoms has been an area of considerable interest recently. Cooled neutral atoms are needed for a variety of interesting experiments involving neutral atom traps and ultrahigh-resolution spectroscopy. Laser cooling of sodium has previously been demonstrated using elegant but quite elaborate apparatus. These techniques employed stabilized dye lasers and a variety of additional sophisticated hardware. The authors have demonstrated that a frequency chirp technique can be implemented using inexpensive diode lasers and simple electronics. In this technique the atoms in an atomic beam scatter resonant photons from a counterpropagating laser beam. The momentum transfer from the photons slows the atoms. The primary difficulty is that as the atoms slow their Doppler shift changes, and so they are no longer in resonance with the incident photons. In the frequency chirp technique this is solved by rapidly changing the laser frequency so that the atoms remain in resonance. To achieve the necessary frequency sweep with a dye laser one must use an extremely sophisticated high-speed electrooptic modulator. With a diode laser, however, the frequency can be smoothly and rapidly varied over many gigahertz simply by changing the injection current

Atomic physics at high brilliance synchrotron sources: Proceedings

International Nuclear Information System (INIS)

Berry, G.; Cowan, P.; Gemmell, D.

1994-08-01

This report contains papers on the following topics: present status of SPring-8 and the atomic physics undulator beamline; recent photoabsorption measurements in the rare gases and alkalis in the 3 to 15 keV proton energy region; atomic and molecular physics at LURE; experiments on atoms, ions and small molecules using the new generation of synchrotron radiation sources; soft x-ray fluorescence spectroscopy using tunable synchrotron radiation; soft x-ray fluorescence spectroscopy excited by synchrotron radiation: Inelastic and resonant scattering near threshold; outer-shell photoionization of ions; overview of the APS BESSRC beamline development; the advanced light source: Research opportunities in atomic and molecular physics; Photoionization of the Ba + ion by 4d shell excitation; decay dynamics of inner-shell excited atoms and molecules; absorption of atomic Ca, Cr, Mn and Cu; High-resolution photoelectron studies of resonant molecular photoionization; radiative and radiationless resonant raman scattering by synchrotron radiation; auger spectrometry of atoms and molecules; some thoughts of future experiments with the new generation of storage rings; Electron spectroscopy studies of argon K-shell excitation and vacancy cascades; ionization of atoms by high energy photons; ion coincidence spectroscopy on rare gas atoms and small molecules after photoexcitation at energies of several keV; an EBIS for use with synchrotron radiation photoionization of multiply charged ions and PHOBIS; gamma-2e coincidence measurements the wave of the future in inner-shell electron spectroscopy; recoil momentum spectroscopy in ion-atom and photon-atom collisions; a study of compton ionization of helium; future perspectives of photoionization studies at high photon energies; and status report on the advanced photon source. These papers have been cataloged separately elsewhere

First principles study on structural, lattice dynamical and thermal properties of BaCeO3

Science.gov (United States)

Zhang, Qingping; Ding, Jinwen; He, Min

2017-09-01

BaCeO3 exhibits impressive application potentials on solid oxide fuel cell electrolyte, hydrogen separation membrane and photocatalyst, owing to its unique ionic and electronic properties. In this article, the electronic structures, phonon spectra and thermal properties of BaCeO3 in orthorhombic, rhombohedral and cubic phases are investigated based on density functional theory. Comparisons with reported experimental results are also presented. The calculation shows that orthorhombic structure is both energetically and dynamically stable under ground state, which is supported by the experiment. Moreover, charge transfer between cations and anions accompanied with phase transition is observed, which is responsible for the softened phonon modes in rhombohedral and cubic phases. Besides, thermal properties are discussed. Oxygen atoms contribute most to the specific heat. The calculated entropy and specific heat at constant pressure fit well with the experimental ones within the measured temperature range.

Determination of trace elements in Egyptian cane sugar (Deshna Factories) by neutron activation, atomic absorption spectrophotometric and inductively coupled plasma-atomic emission spectrometric analysis

International Nuclear Information System (INIS)

Awadallah, R.M.; Sherif, M.K.; Mohamed, A.E.; Grass, F.

1986-01-01

Multielement instrumental neutron activation (INAA), inductively coupled plasma-atomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses were utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P, Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth, respectively. (author)

Photon mass attenuation coefficients, effective atomic numbers and ...

Indian Academy of Sciences (India)

of atomic number Z was performed using the logarithmic regression analysis of the data measured by the authors and reported earlier. The best-fit coefficients so obtained in the photon ..... This photon build-up is a function of thickness and atomic number of the sample and also the incident photon energy, which combine to ...

The L1-shell ionisation of atoms by relativistic particles

International Nuclear Information System (INIS)

Moiseiwitsch, B.L.; Norrington, P.H.

1979-01-01

An expression for the L 1 -shell ionisation cross sections of atoms by high-energy particles has been derived using the relativistic plane-wave Born approximation. The incident and scattered particles are described by Dirac plane waves while Darwin hydrogenic wavefunctions are used for the atomic electrons. A comparison is made with experimental total cross sections for incident electrons in the energy range 1-2 MeV. The agreement is a considerable improvement on that obtained using the non-relativistic planewave Born approximation. (author)

Synthesis of BaTiO3 nanoparticles from TiO2-coated BaCO3 particles derived using a wet-chemical method

Directory of Open Access Journals (Sweden)

Yuuki Mochizuki

2014-03-01

Full Text Available BaCO3 particles coated with amorphous TiO2 precursor are prepared by a wet chemical method to produce BaTiO3 nanoparticles at low temperatures. Subsequently, we investigate the formation behavior of BaTiO3 particles and the particle growth behavior when the precursor is subjected to heat treatment. The state of the amorphous TiO2 coating on the surface of BaCO3 particles depends on the concentration of NH4HCO3, and the optimum concentration is found to be in the range 0.5–1.0 M. Thermogravimetric curves of the BaCO3 particles coated with the TiO2 precursor, prepared from BaCO3 particles of various sizes, show BaTiO3 formation occurring mainly at 550–650 °C in the case of fine BaCO3 particles. However, as evidenced from the curves, the temperature of formation of BaTiO3 shifts to higher values with an increase in the size of the BaCO3 particles. The average particle size of single phase BaTiO3 at heat-treatment temperature of 650–900 °C is observed to be in the range 60–250 nm.

Spectral analysis of Pr{sup 3+} doped germanate glasses modified by BaO and BaF{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Pisarska, Joanna, E-mail: joanna.pisarska@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9 Street, 40-007 Katowice (Poland); Pisarski, Wojciech A. [University of Silesia, Institute of Chemistry, Szkolna 9 Street, 40-007 Katowice (Poland); Dorosz, Dominik; Dorosz, Jan [Bialystok University of Technology, Faculty of Electrical Engineering, Wiejska 45D Street, 15-351 Bialystok (Poland)

2016-03-15

Luminescence properties of Pr{sup 3+} ions in germanate glasses modified by BaF{sub 2} were investigated. Several luminescence bands originating to transitions from the {sup 3}P{sub 0} state to the lower-lying states of Pr{sup 3+} were registered under 450 nm excitation. The spectral analysis suggests that the positions of luminescence bands and their relative intensities are changed significantly with BaF{sub 2} content. The relative integrated luminescence intensities of {sup 3}P{sub 0}→{sup 3}H{sub 4} transition (blue) to the {sup 3}P{sub 0}→{sup 3}F{sub 2} transition (red) of Pr{sup 3+} ions strongly depend on fluoride modifier BaF{sub 2} in glass composition. The luminescence bands of Pr{sup 3+} ions are shifted to shorter wavelengths with increasing BaF{sub 2} content. - Highlights: • Praseodymium doped lead-free germanate glasses modified by BaF{sub 2} were prepared. • Emission spectra correspond to transitions from {sup 3}P{sub 0} state to lower-lying states of Pr{sup 3+}. • The relative emission band intensities of Pr{sup 3+} depend strongly on BaF{sub 2} content. • Emission bands of Pr{sup 3+} are shifted to shorter wavelengths with increasing BaF{sub 2} content.

La-doped BaTiO3 heterostructures: Compensating the polarization discontinuity

Directory of Open Access Journals (Sweden)

D. P. Kumah

2013-12-01

Full Text Available We demonstrate a route to manipulate the polarization and internal electric field of a complex oxide heterostructure using a layering sequence based on the LaAlO3-SrTiO3 interface. By combining sensitive atomic-level mapping of the structure using direct x-ray phase-retrieval methods with theoretical modeling of the electrostatic charge and polarization, we have devised a novel single-domain polar heterostructure. We find that ionic rearrangement results in strain and free energy minimization, and eliminates the polarization discontinuity leading to a two-fold increase of the spontaneous polarization towards the surface of an ultra-thin single-domain BaTiO3 film.

Optical characteristics of BaGa2S4:Ho3+ and BaGa2Se4:Ho3+ single crystals

International Nuclear Information System (INIS)

Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

2005-01-01

BaGa 2 S 4 , BaGa 2 S 4 :Ho 3+ , BaGa 2 Se 4 , and BaGa 2 Se 4 :Ho 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa 2 S 4 :Ho 3+ and the BaGa 2 Se 4 :Ho 3+ single crystals and were assigned to radiation recombination between split Stark levels of Ho 3+ .

Infectious diseases in atomic bomb survivors

International Nuclear Information System (INIS)

Hamada, Tadao; Ishida, Sadamu; Matsushita, Hiroshi.

1976-01-01

Incidences of various infectious diseases in 986 autopsy cases at Hiroshima Atomic Bomb Hospital and Hiroshima Red Cross Hospital from 1965 to 1975 were compared according to the distance from the explosion place, and the following results were obtained. There was not a significant difference at incidences of most infectious diseases between each exposured group and not-exposured group. Incidence of old tuberculosis focus was a little higher in exposured groups, but incidences of main lesions such as tuberculosis, active tuberculosis, and miliary tuberculosis were lower in exposured groups and effect of exposure was negative. Out of urinary tract infections, the nearer the distance to the explosion place was, the higher incidence of cistitis in female was. Incidence of cystitis of female was higher than that of male in the group exposured near to the explosion place. With respect to stomach cancer, leukemia, malignant lymphoma, and cerebrovascular disorder, the nearer the distance to the explosion place was, the higher incidences of various infectious diseases were. (Tsunoda, M.)

Size-corrected BMD decreases during peak linear growth: implications for fracture incidence during adolescence.

Science.gov (United States)

Faulkner, Robert A; Davison, K Shawn; Bailey, Donald A; Mirwald, Robert L; Baxter-Jones, Adam D G

2006-12-01

Peak adolescent fracture incidence at the distal end of the radius coincides with a decline in size-corrected BMD in both boys and girls. Peak gains in bone area preceded peak gains in BMC in a longitudinal sample of boys and girls, supporting the theory that the dissociation between skeletal expansion and skeletal mineralization results in a period of relative bone weakness. The high incidence of fracture in adolescence may be related to a period of relative skeletal fragility resulting from dissociation between bone expansion and bone mineralization during the growing years. The aim of this study was to examine the relationship between changes in size-corrected BMD (BMDsc) and peak distal radius fracture incidence in boys and girls. Subjects were 41 boys and 46 girls measured annually (DXA; Hologic 2000) over the adolescent growth period and again in young adulthood. Ages of peak height velocity (PHV), peak BMC velocity (PBMCV), and peak bone area (BA) velocity (PBAV) were determined for each child. To control for maturational differences, subjects were aligned on PHV. BMDsc was calculated by first regressing the natural logarithms of BMC and BA. The power coefficient (pc) values from this analysis were used as follows: BMDsc = BMC/BA(pc). BMDsc decreased significantly before the age of PHV and then increased until 4 years after PHV. The peak rates in radial fractures (reported from previous work) in both boys and girls coincided with the age of negative velocity in BMDsc; the age of peak BA velocity (PBAV) preceded the age of peak BMC velocity (PBMCV) by 0.5 years in both boys and girls. There is a clear dissociation between PBMCV and PBAV in boys and girls. BMDsc declines before age of PHV before rebounding after PHV. The timing of these events coincides directly with reported fracture rates of the distal end of the radius. Thus, the results support the theory that there is a period of relative skeletal weakness during the adolescent growth period caused, in

The trapping of K and Na atoms by a clean W(110) surface. Dynamic trajectory calculations. ch.3

International Nuclear Information System (INIS)

Hurkmans, A.; Overbosch, E.G.; Los, J.

1976-01-01

The fraction of K and Na atoms which are initially trapped by a clean W(110) surface has been measured as a function of incident energy (0.5 < approximately Esub(i) < approximately 15 eV) at several angles of incidence. At the same time the desorption energies Qsub(i) of the trapped potassium and sodium atoms were measured: Qsub(i) = 2.05 +- 0.02 eV and Qsub(i) = 2.60 +- 0.04 eV respectively. The measured trapping probabilities can be described well by Trillings 'partially screened spherical cap' model, except fos the small angles of incidence. Dynamic trajectory calculations were performed for a particle scattered from a diatomic molecule to explain the screening and the descrepancy at normal incidence. The calculations give good quantitative agreement with the measured trapping probability at small angles both for potassium and sodium atoms and show that simultaneous interaction with two adjacent surface atoms affects the trapping particularly at small angles of incidence. (Auth.)

Molecular dynamics simulation study of the influence of the lattice atom potential function upon atom ejection processes

International Nuclear Information System (INIS)

Harrison, D.E. Jr.; Webb, R.P.

1982-01-01

A molecular dynamics simulation has been used to investigate the sensitivity of atom ejection processes from a single-crystal target to changes in the atom-atom potential function. Four functions, three constructed from the Gibson potentials with Anderman's attractive well, and a fouth specifically developed for this investigation, were investigated in the Cu/Ar/sup +/ system over a range of ion energies from 1.0 to 10.0 kev with the KSE-B ion-atom potential. Well depths and widths also were varied. The calculations were done at normal incidence on the fcc (111) crystal orientation. Computed values were compared with experimental data where they exist. Sputtering yields, multimer yield ratios, layer yield ratios, and the ejected atom energy distribution vary systematically with the parameters of the atom-atom potential function. Calculations also were done with the modified Moliere function. Yields and other properties fall exactly into the positions predicted from the Born-Mayer function analysis. Simultaneous analysis of the ejected atom energy distribution and the ion energy dependence of the sputtering yield curve provides information about the parameters of both the wall and well portions of the atom-atom potential function

Measurement of effective atomic number of composite materials using scattering of γ-rays

International Nuclear Information System (INIS)

Singh, M.P.; Sandhu, B.S.; Singh, Bhajan

2007-01-01

In the present experiment, to determine the effective atomic number of composite materials, the scattering of 145 keV γ-rays is studied using a high-resolution HPGe semiconductor detector placed at 70 deg. to the incident beam. The experiment is performed on various elements of different atomic number, 6≤Z≤64, for 145 keV incident photons. The intensity ratio of Rayleigh to Compton scattered peaks, corrected for photo-peak efficiency of the γ-detector and absorption of photons in the target and air, is plotted as a function of atomic number and constituted a fit curve. From this fit curve, the respective effective atomic numbers of the composite materials are determined. The agreement of measured values of effective atomic number with the theory is found to be quite satisfactory

Positronium-alkali atom scattering at medium energies

International Nuclear Information System (INIS)

Chakraborty, Ajoy; Basu, Arindam; Sarkar, Nirmal K; Sinha, Prabal K

2004-01-01

We investigate the scattering of orthopositronium (o-Ps) atom off different atomic alkali targets (Na to Cs) at low and medium energies (up to 120 eV). Projectile-elastic and target-elastic close-coupling models have been employed to investigate the systems in addition to the static-exchange model. Elastic, excitation and total cross sections have been reported for all four systems. The magnitude of the alkali excitation cross section increases with increasing atomic number of the target atom while the position of the peak value shifts towards lower incident energies. The magnitudes of the Ps excitation and ionization cross sections increase steadily with atomic number with no change in the peak position. The reported results show regular behaviour with increasing atomic number of the target atom. Scattering parameters for the Ps-Rb and Ps-Cs systems are being reported for the first time

Incorporation of Ba in Al and Fe pollucite

Energy Technology Data Exchange (ETDEWEB)

Vance, Eric R., E-mail: erv@ansto.gov.au [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gregg, Daniel J.; Griffiths, Grant J. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia); Gaugliardo, Paul R. [Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, WA 6009 (Australia); Grant, Charmaine [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001 Kirrawee DC, NSW 2232 (Australia)

2016-09-15

Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs{sub (1−2x)}Ba{sub x}AlSi{sub 2}O{sub 6} aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl{sub 2}Si{sub 2}O{sub 8} phases. The effect of Ba substitution in pollucite-structured CsFeSi{sub 2}O{sub 6} was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe{sup 2+} formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs{sup +} + Fe{sup 3+} ↔ Ba{sup 2+} + Ni{sup 2+} scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi{sub 2}O{sub 6} to be very leach resistant. - Highlights: • Barium can be incorporated into aluminium pollucite. • Positron annihilation lifetime spectroscopy supports a charge vacancy mechanism of incorporation. • Iron pollucite does not appear to incorporate any barium with either vacancy or charge compensation mechanisms. • Leaching data suggest iron pollucite is very leach resistant.

Colorectal cancer incidence among atomic bomb survivors, 1950-80

International Nuclear Information System (INIS)

Nakatsuka, Hirofumi; Shimizu, Yukiko; Yamamoto, Tsutomu

1992-01-01

Colorectal cancer incidence in the Life Span Study (LSS) sample during 1950-80 was investigated. A total of 730 incidence cases of colorectal cancer were confirmed from a variety of sources. Sixty-two percent of the cancers were microscopically verified and 12% were ascertained through death certificate only. The risk of colon cancer increased significantly with intestinal dose, but no definite increase of risk was observed for rectal cancer. Relative risk at 1 Sv and excess risk per 10 4 PY-Sv for colon cancer are 1.80 (90% confidence interval 1.37-2.36) and 0.36 (90% confidence interval 0.06-0.77) respectively. City and sex did not significantly modify the dose-response of colon cancer, but the risk decreased with age at the time of bombings (ATB). The relative risk of colon cancer does not vary substantially over time following exposure. A non-linear dose response did not significantly improve the fit. Further, the anatomic location of the tumors indicate that the cecum and ascending, transverse and descending, and sigmoid colon seem equally sensitive to radiation. No difference in the distribution of tumor histological types could be observed by radiation dose. (author)

Colorectal cancer incidence among atomic bomb survivors, 1950-80

International Nuclear Information System (INIS)

Hirofumi Nakatsuka; Yukiko Shimizu; Tsutomu Yamamoto; Ichiro Sekine; Haruo Ezaki; Eiichi Tahara; Makoto Takahashi; Takatoshi Shimoyama; Nobuo Mochinaga; Masao Tomita; Ryoichi Tsuchiya; Land, Charles E.

1992-10-01

Colerectal cancer incidence in the LSS sample during 1950-80 was investigated. A total of 730 incidence cases of colorectal cancer were confirmed from a variety of sources. Sixty-two percent of the cancers were microscopically verified and 12% were ascertained through death certificate only. The risk of colon cancer increased significantly with intestinal dose, but no definite increase of risk was observed for rectal cancer. Relative risk at 1 Sv and excess risk per 10 4 PY-Sv for colon cancer are 1.80 (90% confidence internal 1.37-2.36) and 0.36 (90% confidence interval 0.06-0.77) respectively. City and sex did not significantly modify the dos-response of colon cancer, but the risk decreased with age at the time of bombings (ATB). The relative risk of colon cancer does not vary substantially over time following exposure. A non-linear dose response did not significantly improve the fit. Further, the anatomic location of the tumors indicate that the cecum and ascending, transverse and descending, and sigmoid colon seem equally sensitive to radiation. No difference in the distribution of tumor histological types could be observed by radiation dose. (author)

On the Debye-Waller factor in atom-surface scattering

International Nuclear Information System (INIS)

Garcia, N.; Maradudin, A.A.; Celli, V.

1982-01-01

A theory for the Debye-Waller factor in atom-surface scattering is presented, to lowest order in the phonon contributions. Multiple-scattering effects as well as the cross-correlated surface atom displacements are included. The theory accounts for experimental data without the necessity of introducing the Armand effect, which is due to the finite size of the incident atom. The work presented here implies that the Kirchhoff approximation fails when the energy of the incident particle is in the energy range of the phonon spectrum. The results of the calculation are presented in the high-temperature limit, and it is observed that the Rayleigh surface phonons contribute three-quarters of the Debye-Waller factor, while the bulk phonons account for the rest. This result is interesting because the calculation of the former contribution is simpler than that of the latter. (author)

Zintl-phases with layer anions: preparation and crystal structures of the isotypic compounds SrSn sub 2 As sub 2 and Sr sub 0. 87 Ba sub 0. 13 Sn sub 2 As sub 2 and a single crystal structure determination of KSnSb. Zintl-Phasen mit Schichtanionen: Darstellung und Kristallstrukturen der isotypen Verbindungen SrSn sub 2 As sub 2 und Sr sub 0,87 Ba sub 0,13 Sn sub 2 As sub 2 sowie eine Einkristallstrukturbestimmung von KSnSb

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, B; Klein, J [Abt. 2 fuer Anorganische Chemie, Technische Hochschule Darmstadt (Germany)

1991-06-01

The metallic reflecting compounds SrSn{sub 2}As{sub 2} and Sr{sub 0.87}Ba{sub 0.13}Sn{sub 2}As{sub 2} were prepared from the melt, they crystallize in the trigonal rhombohedral system (space group R3m, Z = 3) with lattice constants see ''Inhaltsuebersicht''. In the crystal structure of the isotypic compounds threebonded Sn atoms and threebonded As atoms together form puckered layers which are isostructural to grey As. The mean values of the bond lengths Sn -- As are 277.6 pm (SrSn{sub 2}As{sub 2}) and 279.1 pm (Sr{sub 0.87}Ba{sub 0.13}Sn{sub 2}As{sub 2}) resp. Along (001) the alkaline earth atoms occupy the octahedral interstices of As atoms between each second SnAs layer. The single crystal structure determination of KSnSb confirms the results of the X-ray powder analysis, but leads to slightly different values for the bond lengths.

Submillimeter and microwave residual losses in epitaxial films of Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O

International Nuclear Information System (INIS)

Miller, D.; Richards, P.L.; Eom, C.B.; Geballe, T.H.; Etemad, S.; Inam, A.; Venkatesan, T.; Martens, J.S.; Lee, W.Y.

1992-12-01

We have used a novel bolometric technique and a resonant technique to obtain accurate submillimeter and microwave residual loss data for epitaxial thin films of YBa 2 Cu 3 O 7 , Tl 2 Ca 2 Ba 2 Cu 3 O 10 and Tl 2 CaBa 2 Cu 2 O 8 . For all films we obtain good agreement between the submillimeter and microwave data, with the residual losses in both the Y-Ba-Cu-O and Tl-Ca-Ba-Cu-O films scaling approximately as frequency squared below ∼ 1 THz. We are able to fit the losses in the Y-Ba-Cu-O films to a two fluid and a weakly coupled grain model for the a-b planeconductivity, in good agreement with results from a Kramers-Kronig analysis of the loss data

Effect of annealing time on morphological characteristics of Ba(Zr,Ti)O3 thin films

International Nuclear Information System (INIS)

Cavalcante, L.S.; Anicete-Santos, M.; Pontes, F.M.; Souza, I.A.; Santos, L.P.S.; Rosa, I.L.V.; Santos, M.R.M.C.; Santos-Junior, L.S.; Leite, E.R.; Longo, E.

2007-01-01

Ba(Zr 0.50 Ti 0.50 )O 3 thin films were prepared by the polymeric precursor method using the annealing low temperature of 300 o C for 8, 16, 24, 48, 96 and 192h in a furnace tube with oxygen atmosphere. The X-ray diffraction patterns revealed that the film annealed for 192 h presented some crystallographic planes (1bar 0bar 0) (1bar 1bar 0) and (2bar 0bar 0) in its crystalline lattice. Fourier transformed infrared presented the formation of metal-oxygen stretching at around 756cm -1 . The atomic force microscopy analysis presented the growth of granules in the Ba(Zr 0.50 Ti 0.50 )O 3 films annealed from 8 to 96h. The crystalline film annealed for 192h already presents grains in its perovskite structure. It evidenced a reduction in the thickness of the thin films with the increase of the annealing time

Structures and Heats of Formation of Simple Alkaline Earth Metal Compounds II: Fluorides, Chlorides, Oxides, and Hydroxides for Ba, Sr, and Ra.

Science.gov (United States)

Vasiliu, Monica; Hill, J Grant; Peterson, Kirk A; Dixon, David A

2018-01-11

Geometry parameters, vibrational frequencies, heats of formation, bond dissociation energies, cohesive energies, and selected fluoride affinities (difluorides) are predicted for the late alkaline earth (Sr, Ba, and Ra) oxides, fluorides, chlorides, and hydroxides at the coupled cluster theory CCSD(T) level. Additional corrections (scalar relativistic and pseudopotential corrections, vibrational zero-point energies, and atomic spin-orbit effects) were included to accurately calculate the total atomization energies and heats of formation following the Feller-Peterson-Dixon methodology. The calculated values are compared to the experimental data where available. In some cases, especially for Ra compounds, there are no experimental results, or the experimental energetics and geometries are not reliable or have very large error bars. All of the Sr, Ba, and Ra difluorides, dichlorides, and dihydroxides are bent structures with the OMO bond angles decreasing going down the group. The cohesive energies of bulk Be dihalides are predicted to be quite low, while those of Ra are relatively large. The fluoride affinities show that the difluorides are moderately strong Lewis acids and that such trifluorides may form under the appropriate experimental conditions.

Monte Carlo calculation of secondary electron emission from carbon-surface by obliquely incident particles

International Nuclear Information System (INIS)

Ohya, Kaoru; Kawata, Jun; Mori, Ichiro

1990-01-01

Incidence angle dependences of secondary electron emission from a carbon surface by low energy electron and hydrogen atom are calculated using Monte Carlo simulations on the kinetic emission model. The calculation shows very small increase or rather decrease of the secondary electron yield with oblique incidence. It is explained in terms of not only multiple elastic collisions of incident particles with the carbon atoms but also small penetration depth of the particles comparable with the escape depth of secondary electrons. In addition, the two types of secondary electron emission are distinguished by using the secondary electron yield statistics; one is the emission due to trapped particles in the carbon, and the other is that due to backscattered particles. The high-yield component of the statistics on oblique incidence is more suppressed than those on normal incidence. (author)

Charge-state-distributions of foil-excited heavy Rydberg atoms

International Nuclear Information System (INIS)

Faibis, A.; Kanter, E.P.; Koenig, W.; Zabransky, B.J.

1985-01-01

Studies of foil-excited fast (MeV/amu) heavy ions have demonstrated large yields of high Rydberg atoms formed in such beams. Further experiments have suggested a strong target-thickness dependence of the yields of such atoms. These results have been puzzling in view of the supposed short mean free paths of such atoms in solids. In an effort to better understand these results, the authors have measured the yields of Rydberg atoms (napprox.100-200) in foil-excited 32 S ions at an incident energy of 125 MeV

Polarization-induced interference within electromagnetically induced transparency for atoms of double-V linkage

Science.gov (United States)

Sun, Yuan; Liu, Chang; Chen, Ping-Xing; Liu, Liang

2018-02-01

People have been paying attention to the role of atoms' complex internal level structures in the research of electromagnetically induced transparency (EIT) for a long time, where the various degenerate Zeeman levels usually generate complex linkage patterns for the atomic transitions. It turns out, with special choices of the atomic states and the atomic transitions' linkage structure, clear signatures of quantum interference induced by the probe and coupling light's polarizations can emerge from a typical EIT phenomena. We propose to study a four-state system with double-V linkage pattern for the transitions and analyze the polarization-induced interference under the EIT condition. We show that such interference arises naturally under mild conditions on the optical field and atom manipulation techniques. Moreover, we construct a variation form of double-M linkage pattern where the polarization-induced interference enables polarization-dependent cross modulation between incident weak lights that can be effective even at the few-photon level. The theme is to gain more insight into the essential question: how can we build a nontrivial optical medium where incident lights experience polarization-dependent nonlinear optical interactions, valid for a wide range of incidence intensities down to the few-photon level?

Processing of R-Ba-Cu-O superconductors

International Nuclear Information System (INIS)

Wu, H.

1998-01-01

Precipitation processes were developed to introduce second phases as flux pinning centers in Gd-Ba-Cu-O and Nd-Ba-Cu-O superconductors. In Gd-Ba-Cu-O, precipitation is caused by the decrease of the upper solubility limit of Gd 1+x Ba 2-x Cu 3 O 7 solid solution (Gd123ss) in low oxygen partial pressure. Processing of supersaturated Gd 1.2 Ba 1.8 Cu 3 O 7 in low oxygen partial pressure can produce dispersed second phases. Gd211 is formed as a separate phase while extensive Gd124 type stacking fault is formed instead of a separate CuO phase. As a result of the precipitation reaction, the transition temperature and critical current density are increased. In Nd-Ba-Cu-O, precipitation is caused by the decrease of the lower solubility limit of Nd 1+x Ba 2-x Cu 3 O 7 solid solution (Nd123ss) in oxygen. DTA results reveal the relative stability of Nd123ss in different oxygen partial pressures. In 1 bar oxygen partial pressure, Nd123ss with x = 0.1 is the most stable phase. In lower oxygen partial pressures, the most stable composition shifts towards the stoichiometric composition. The relative stability changes faster with decreasing oxygen partial pressure. Therefore, processing in oxygen and air tends to produce broad superconducting transitions but sharp transitions can be achieved in 0.01 bar and 0.001 bar oxygen partial pressures. While the lower solubility limits in 0.01 bar and 0.001 bar oxygen partial pressures remain at x = 0.00, the solubility limits in oxygen and air show a narrowing with decreasing temperature. Because of the narrowing of the solubility range in oxygen, oxygen annealing of Nd123 initially processed in low oxygen partial pressures will result in precipitation of second phases. The equilibrium second phase is BaCuO 2 for temperature above 608 C, and at lower temperatures the equilibrium second phases are Ba 2 CuO 3.3 and Ba 2 Cu 3 O 5+y . However, annealing at low temperature may produce a fine metastable transition phase. A coherent intermediate

Atomic radii for atoms with the 6s shell outermost: The effective atomic radius and the van der Waals radius from 55Cs to 80Hg

Directory of Open Access Journals (Sweden)

Hiroshi Tatewaki

2015-06-01

Full Text Available We consider, for atoms from 55Cs to 80Hg, the effective atomic radius (rear, which is defined as the distance from the nucleus at which the magnitude of the electric field is equal to that in He at one half of the equilibrium bond length of He2. The values of rear are about 50% larger than the mean radius of the outermost occupied orbital of 6s, . The value of rear decreases from 55Cs to 56Ba and undergoes increases and decreases with rising nuclear charge from 57La to 70Y b. In fact rear is understood as comprising two interlaced sequences; one consists of 57La, 58Ce, and 64Gd, which have electronic configuration (4fn−1(5d1(6s2, and the remaining atoms have configuration (4fn(6s2. The sphere defined by rear contains 85%–90% of the 6s electrons. From 71Lu to 80Hg the radius rear also involves two sequences, corresponding to the two configurations 5dn+16s1 and 5dn6s2. The radius rear according to the present methodology is considerably larger than rvdW obtained by other investigators, some of who have found values of rvdW close to .

TRANSITIVITY AND THE BA CONSTRUCTION

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Pei-Jung Kuo

2010-06-01

Full Text Available In this paper, I discuss the legitimacy of positing a Transitivity Projection (= TrP cf. Bowers 1993, 1997, 2001 and 2002 in the BA construction in Mandarin Chinese. BA has been proposed to be a semantically-bleached verb, inserted in the v position (Huang 1997 and Lin 2001. Several pieces of evidence such as manner adverbial placement (cf. Huang, Li and Li 2009 and GEI-insertion (cf. Tang 2001 indicate that there must be a functional projection between the vP and VP to host the BA NP. I propose that a TrP is probably the most apt candidate for the XP. I also argue, in contrast to the proposal by Huang, Li and Li (2009, that the present proposal which employs a TrP captures most of the properties of the BA construction. A comparison with the structure of the BEI construction also shows that the TrP proposal fits into the general picture of current linguistic theory on transitive constructions without extra stipulations.

Polarization-dependent atomic dipole traps behind a circular aperture for neutral-atom quantum computing

International Nuclear Information System (INIS)

Gillen-Christandl, Katharina; Copsey, Bert D.

2011-01-01

The neutral-atom quantum computing community has successfully implemented almost all necessary steps for constructing a neutral-atom quantum computer. We present computational results of a study aimed at solving the remaining problem of creating a quantum memory with individually addressable sites for quantum computing. The basis of this quantum memory is the diffraction pattern formed by laser light incident on a circular aperture. Very close to the aperture, the diffraction pattern has localized bright and dark spots that can serve as red-detuned or blue-detuned atomic dipole traps. These traps are suitable for quantum computing even for moderate laser powers. In particular, for moderate laser intensities (∼100 W/cm 2 ) and comparatively small detunings (∼1000-10 000 linewidths), trap depths of ∼1 mK and trap frequencies of several to tens of kilohertz are achieved. Our results indicate that these dipole traps can be moved by tilting the incident laser beams without significantly changing the trap properties. We also explored the polarization dependence of these dipole traps. We developed a code that calculates the trapping potential energy for any magnetic substate of any hyperfine ground state of any alkali-metal atom for any laser detuning much smaller than the fine-structure splitting for any given electric field distribution. We describe details of our calculations and include a summary of different notations and conventions for the reduced matrix element and how to convert it to SI units. We applied this code to these traps and found a method for bringing two traps together and apart controllably without expelling the atoms from the trap and without significant tunneling probability between the traps. This approach can be scaled up to a two-dimensional array of many pinholes, forming a quantum memory with single-site addressability, in which pairs of atoms can be brought together and apart for two-qubit gates for quantum computing.

Structural evolution of Ba8Ti3Nb4O24 from BaTiO3 using a series of Ba(Ti1−5xNb4x)O3 solid solutions

International Nuclear Information System (INIS)

Barrientos Hernández, F.R.; Lira Hernández, I.A.; Gómez Yáñez, C.; Arenas Flores, A.; Cabrera Sierra, R.; Pérez Labra, M.

2014-01-01

Highlights: • The evolution phase Ba 8 Ti 3 Nb 4 O 24 was obtained through the mechanism Ba(Ti 1-5x Nb 4x )O 3 . • Addition of niobium can accelerate grain growth of BaTiO 3 ceramics. • Ba 8 Ti 3 Nb 4 O 24 presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb 5+ content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba 8 Ti 3 Nb 4 O 24 by adding Nb 2 O 5 to perovskite structure of BaTiO 3 was investigated. The compositions Ba(Ti 1-5x Nb 4x )O 3 ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO 3 , BaCO 3 and Nb 2 O 5 , were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba 8 Ti 3 Nb 4 O 24 from BaTiO 3 was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba 8 Ti 3 Nb 4 O 24 which resonates at microwave frequencies

Structure and physical properties of type-I clathrate solid-solution Ba8PtxGe46-x-y□y (□=vacancy)

International Nuclear Information System (INIS)

Melnychenko-Koblyuk, N.; Grytsiv, A.; Rogl, P.; Rotter, M.; Lackner, R.; Bauer, E.; Fornasari, L.; Marabelli, F.; Giester, G.

2007-01-01

Formation, crystal chemistry, and physical properties were investigated for the solid-solution Ba 8 Pt x Ge 46-x-y □ y (□ is a vacancy) deriving from binary clathrate Ba 8 Ge 43 □ 3 with a solubility limit of ∼3.5 Pt atoms/f.u. at T=800 deg. C. Structural investigations throughout the homogeneity region confirm isotypism with the cubic primitive clathrate type-I structure (space group type Pm3n) and lattice parameters ranging from a=1.0657(2) nm for Ba 8 Ge 43 □ 3 to a=1.0752(2) nm for Ba 8 Pt 3.5 Ge 41.5 □ 1.0 . Phase relations for the region concerning the clathrate solution were derived at subsolidus temperatures as well as at 800 deg. C. Transport properties evidence electrons as the majority charge carriers in the system with a slight dependency on the Pt content. The system is located close to a semiconducting regime with a gap in the electronic density of states of a few thousand K. No low temperature maximum is obvious from thermal conductivity which is dominated by the lattice contribution. Thermal conductivity furthermore documents a high efficiency of phonon scattering on vacancies

Structure of high-Tc superconducting tetragonal Ba2YCu2.856Al0.04O6.76 at 298 and 120 K

International Nuclear Information System (INIS)

Sato, S.

1989-01-01

It was found by chemical analysis that a slight amount of aluminium existed as an impurity in the crystals of the Y-Ba-Cu-O system whose structure was determined by Sato, Nakada, Kohara and Oda. Occupancies of atoms in 1(a) [the Cu(1) site] were 0.856(5) Cu, 0.04 Al and 0.104 vacancy. (orig.)

Complementary resistive switching in BaTiO{sub 3}/NiO bilayer with opposite switching polarities

Energy Technology Data Exchange (ETDEWEB)

Li, Shuo [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Institut d’Electronique de Micro-électronique et de Nanotechnologie (IEMN), CNRS, Université des Sciences et Technologies de Lille, avenue Poincaré, BP 60069, 59652, Villeneuve d’Ascq cedex (France); Wei, Xianhua, E-mail: weixianhua@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Lei, Yao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China); Yuan, Xincai [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zeng, Huizhong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronics Science and Technology of China, Chengdu 610054 (China)

2016-12-15

Graphical abstract: Au/BaTiO{sub 3}/NiO/Pt bilayer device shows complementary resistive switching (CRS) without electroforming which is mainly ascribed to anti-serial stack of two RRAM cells with bipolar behaviors. - Highlights: • Complementary resistive switching (CRS) has been investigated in Au/BaTiO{sub 3}/NiO/Pt by stacking the two elements with different switching types. • The realization of complementary resistive switching (CRS) is mainly ascribed to the anti-serial stack of two RRAM cells with bipolar behaviors. • Complementary resistive switching (CRS) in bilayer is effective to solve the sneak current problem briefly and economically. - Abstract: Resistive switching behaviors have been investigated in the Au/BaTiO{sub 3}/NiO/Pt structure by stacking the two elements with different switching types. The conducting atomic force microscope measurements on BaTiO{sub 3} thin films and NiO thin films suggest that with the same active resistive switching region, the switching polarities in the two semiconductors are opposite to each other. It is in agreement with the bipolar hysteresis I–V curves with opposite switching polarities for single-layer devices. The bilayer devices show complementary resistive switching (CRS) without electroforming and unipolar resistive switching (URS) after electroforming. The coexistence of CRS and URS is mainly ascribed to the co-effect of electric field and Joule heating mechanisms, indicating that changeable of resistance in this device is dominated by the redistribution of oxygen vacancies in BaTiO{sub 3} and the formation, disruption, restoration of conducting filaments in NiO. CRS in bilayer with opposite switching polarities is effective to solve the sneak current without the introduction of any selector elements or an additional metal electrode.

Biological age as a health index for mortality and major age-related disease incidence in Koreans: National Health Insurance Service – Health screening 11-year follow-up study

Directory of Open Access Journals (Sweden)

Kang YG

2018-03-01

Full Text Available Young Gon Kang,1 Eunkyung Suh,2 Jae-woo Lee,3 Dong Wook Kim,4 Kyung Hee Cho,5 Chul-Young Bae1 1Department of R&D, MediAge Research Center, Seongnam, Republic of South Korea; 2Department of Family Medicine, College of Medicine, CHA University, Chaum, Seoul, Republic of South Korea; 3Department of Family Medicine, College of Medicine, Chungbuk National University, Cheongju, Republic of South Korea; 4Department of Policy Research Affairs, National Health Insurance Service Ilsan Hospital, Goyang, Republic of South Korea; 5Department of Family Medicine, National Health Insurance Service Ilsan Hospital, Goyang, Republic of South KoreaPurpose: A comprehensive health index is needed to measure an individual’s overall health and aging status and predict the risk of death and age-related disease incidence, and evaluate the effect of a health management program. The purpose of this study is to demonstrate the validity of estimated biological age (BA in relation to all-cause mortality and age-related disease incidence based on National Sample Cohort database.Patients and methods: This study was based on National Sample Cohort database of the National Health Insurance Service – Eligibility database and the National Health Insurance Service – Medical and Health Examination database of the year 2002 through 2013. BA model was developed based on the National Health Insurance Service – National Sample Cohort (NHIS – NSC database and Cox proportional hazard analysis was done for mortality and major age-related disease incidence.Results: For every 1 year increase of the calculated BA and chronological age difference, the hazard ratio for mortality significantly increased by 1.6% (1.5% in men and 2.0% in women and also for hypertension, diabetes mellitus, heart disease, stroke, and cancer incidence by 2.5%, 4.2%, 1.3%, 1.6%, and 0.4%, respectively (p<0.001.Conclusion: Estimated BA by the developed BA model based on NHIS – NSC database is expected to be

Lung cancer among atomic-bomb survivors

International Nuclear Information System (INIS)

Hamada, Tadao; Akamizu, Hiroshi

1984-01-01

Patho-statistical study of the relationship between lung cancer and the atomic-bomb (A-bomb) was made on 259 lung cancer cases autopsied in Hiroshima Atomic Bomb Hospital between 1956 and 1983. These autopsy cases were divided into 3 groups; those exposed at 2000 m from the hypocenter or those entering the city after the bombing (group B), and non-exposed group. The incidence of lung cancer was high irrespective of sex in the group A, being 1.8 times higher than in the non-exposed group. It tended to increase rapidly since 1975 in women of the group A, and the ratio of women to men was high, as compared with the other groups. In the group B and the non-exposed group, the incidence of lung cancer tended to increase year by year, particularly in men. Grip-sized adenocarcinoma was seen more frequently in the group A than in the other groups. Squamous cell carcinoma and undifferentiated cancer occurred more frequently than adenocarcinoma in older women of the exposed groups. This seemed to be due to the fact that older patients tended to have squamous cell carcinoma or undifferentiated cancer more frequently than adenocarcinoma. The incidence of lung cancer, particularly adenocarcinoma, tended to increase in the exposed groups. There was no great difference in the incidence of organ metastasis between the exposed groups and non-exposed group. Twenty-one of 24 cases of multiple cancer were A-bomb victims, although the incidence of complications was independent of exposure status. (Namekawa, K.)

Spectroscopic and thermal degradation behavior of Mg(II, Ca(II, Ba(II and Sr(II complexes with paracetamol drug

Directory of Open Access Journals (Sweden)

Moamen S. Refat

2017-05-01

Full Text Available Complexes of Mg(II, Ca(II, Ba(II and Sr(II with paracetamol drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR, and 1H NMR spectroscopy and thermal analysis, as well as screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as paracetamol behaves as a neutral bidentate ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the amide group. From the microanalytical data, the stoichiometry of the complexes reacts with Mg(II, Ca(II, Ba(II and Sr(II by molar ratios (2:1 (paracetamol:metal ion. The thermal behavior (TG/DTG of the complexes was studied. The ligand and their metal complexes were screened against both of antibacterial and fungicidal activities.

Skin cancer of Nagasaki atomic bomb survivors, 4

International Nuclear Information System (INIS)

Sadamori, Naoki; Mine, Mariko; Hori, Makoto; Noda, Yoshinori; Fujiwara, Naoko; Takahara, Osamu; Sadamori, Michiko; Nishimoto, Katsutaro; Ota, Hisahiro.

1990-01-01

We previously reported that there was a high correlation between the exposure dose and the incidence of skin cancer in A-bomb survivors using the data of the Nagasaki Life Span Study of Radiation Effects Research Foundation and Nagasaki Tumor Registry. In Report 3 of this series, we clarified that the correlation between the exposure distance and the incidence of skin cancer was statistically significant in 140 cases of skin cancer collected from 31 hospitals in Nagasaki City and adjacent districts on the basis of the data of the total 66,276 A-bomb survivors recorded in the Scientific Data Center of Atomic Bomb Disaster, Nagasaki University School of Medicine, and that the correlation was the same even when the cases were divided by sex. In this report, we examined the chronological change of the incidence of skin cancer in Nagasaki A-bomb survivors, using the data of the Scientific Data Center of Atomic Bomb Disaster. It is likely that the incidence of skin cancer in Nagasaki A-bomb survivors has increased after 1962, especially after 1975 in those exposed within 2.5km from the hypocenter compared to those exposed at 3.0km or more. (author)

Separation of Sr from Ca, Ba and Ra by means of Ca(OH)2 and Ba(Ra)Cl2 or Ba(Ra)SO4 for the determination of radiostrontium

DEFF Research Database (Denmark)

Chen, Q.J.; Hou, Xiaolin; Yu, Y.X.

2002-01-01

be completed. The new separation procedure has been successfully used for the determination of Sr-90 in samples with high Ca content, such as 451 of seawater and 2001 of drinking water. The analytical quality of the results is comparable to that of the traditional method using fuming nitric acid and BaCrO4......A simple procedure is developed to separate Sr from a large amount of Ca, which relies on the insolubility of Ca(OH)(2) in alkaline solution. Calcium is quantitatively separated from Sr and more than 95% of Sr is recovered from a sample with as much as 50 g of Ca and a Ca/Sr mole ratio of 250....... A new procedure for the separation of Sr from Ba and Ra is also investigated, which is based on the difference in solubility of the chlorides of Sr, Ba and Ra in HCl media. In 9.5 mol 1(-1) HCl or 7.5 mol 1(-1) HCl-10% acetone media, >97% of Ba and Ra can be removed by Ba(Ra)Cl-2 precipitation, and >94...

Characterization and dielectric properties of BaTiO3 prepared from Ba(NO3)2-TiO2 mixture

International Nuclear Information System (INIS)

Othman, K.I.; Hassan, A.A.; Ali, M.E.; Abdelal, O.A.; Salah El Dien, F.E.; El-Raghy, S.M.; Abdel-Karim, R.

2012-01-01

BaTiO 3 powder was prepared through a solid-state reaction between the Ba(NO 3 ) 2 and TiO 2 . The thermal analysis and XRD techniques were used to study its formation. A single phase BaTiO 3 was formed after calcination at 600 degree C for 6 hrs. The dielectric properties of the sintered BaTiO 3 were determined in the temperature range from room temperature to 20 degree C at a frequency ranging from 500 Hz to 100 khz. The relative permittivity and the dielectric loss of the sintered pellets at 1 khz, measured at room temperature,were 1805 and 0.419 respectively.

HRTEM analysis on nanocrystalline BaTiO3 and PbTiO3: size effects on ferroelectric phase transition temperature

International Nuclear Information System (INIS)

Bursill, L.A.; Jiang, B.; Peng, J.L.; Zhong, W.L.; Zhang, P.L.

1997-01-01

High-Resolution Transmission Electron Microscopic studies of nanocrystaline particles of BaTiO 3 and PbTiO 3 are reported. There are characteristic differences observed for BaTiO 3 prepared using sol gel (SG) and steric acid gel (SAG) methods. The former exhibit a critical size below which there is no paraelectric/ferroelectric phase transition, whereas BaTiO 3 prepared via the SAG route remained cubic for all conditions. The SAG preparations always showed chemical intergrowth defects whereas the SG preparations were single phase. Atomic resolution images of both varieties showed interesting surface steps and surface relaxations/reconstructions of some facets. Nanocrystalline PbTiO 3 prepared by the SG route remains tetragonal, albeit with decreasing c/a ratio, down to 25nm diameter. HRTEM observations of nanocrystalline PbTiO 3 are also presented. X-ray diffraction, dielectric and Raman scattering measurements also demonstrate pronounced size effects. The relationship between the observed nanostructures and size effects on the physical properties is discussed. 6 refs., 1 tab., 6 figs

Synthesis, crystal structure and electrical properties of A-site cation ordered BaErMn2O5 and BaErMn2O6

International Nuclear Information System (INIS)

Świerczek, Konrad; Klimkowicz, Alicja; Zheng, Kun; Dabrowski, Bogdan

2013-01-01

In this paper, we report on a synthesis procedure, structural and electrical properties of BaErMn 2 O 5 and BaErMn 2 O 6 , A-site double perovskites having layered arrangement of Ba and Er cations. These materials belong to a family of BaLnMn 2 O 5+δ oxides, which up to now were successfully synthesized for Ln=Y and La–Ho lanthanides. Up to our knowledge, this is the first report on the successful synthesis of BaErMn 2 O 5 and BaErMn 2 O 6 , yielding>95 wt% of the considered compounds. Structural characterization of the materials is given at room temperature, together with in situ XRD studies, performed during oxidation of BaErMn 2 O 5 in air, at elevated temperatures up to 500 °C. A complex structural behavior was observed, with oxidation process of BaErMn 2 O 5 occurring at around 300 °C. The oxidized BaErMn 2 O 6 shows a structural phase transition at about 225 °C. Results of structural studies are supported by thermogravimetric measurements of the oxidation process, performed in air, as well as reduction process, preformed in 5 vol% of H 2 in Ar. Additionally, isothermal oxidation/reduction cycles were measured at 500 °C, showing interesting properties of BaErMn 2 O 5+δ , from a point of view of oxygen storage technology. Electrical conductivity of BaErMn 2 O 5 is of the order of 10 −4 S cm −1 at room temperature and shows activated character on temperature with activation energy E a =0.30(1) eV. Positive sign of Seebeck coefficient for this material indicates holes as dominant charge carriers. Oxidized BaErMn 2 O 6 possesses much higher electrical conductivity, almost 0.2 S cm −1 at room temperature. Additional, about 10-fold increase of electrical conductivity, occurring in the vicinity of 225 °C for this material, can be associated with phase transition from charge/orbital-ordered insulator COI(CE) to paramagnetic metal PM phase. The highest conductivity for BaErMn 2 O 6 was measured near 500 °C and is almost equal to 40 S cm −1 , while

Evolution of atomic-scale surface structures during ion bombardment: A fractal simulation

International Nuclear Information System (INIS)

Shaheen, M.A.; Ruzic, D.N.

1993-01-01

Surfaces of interest in microelectronics have been shown to exhibit fractal topographies on the atomic scale. A model utilizing self-similar fractals to simulate surface roughness has been added to the ion bombardment code TRIM. The model has successfully predicted experimental sputtering yields of low energy (less then 1000 eV) Ar on Si and D on C using experimentally determined fractal dimensions. Under ion bombardment the fractal surface structures evolve as the atoms in the collision cascade are displaced or sputtered. These atoms have been tracked and the evolution of the surface in steps of one monolayer of flux has been determined. The Ar--Si system has been studied for incidence energies of 100 and 500 eV, and incidence angles of 0 degree, 30 degree, and 60 degree. As expected, normally incident ion bombardment tends to reduce the roughness of the surface, whereas large angle ion bombardment increases the degree of surface roughness. Of particular interest though, the surfaces are still locally self-similar fractals after ion bombardment and a steady state fractal dimension is reached, except at large angles of incidence

Graphite Furnace Atomic Absorption Elemental Analysis of Ecstasy Tablets

OpenAIRE

French, Holly E.; Went, Michael J.; Gibson, Stuart J.

2013-01-01

Abstract: Six metals (Cu, Mg, Ba, Ni, Cr, Pb) were determined in two separate batches of seized ecstasy\\ud tablets by graphite furnace atomic absorption spectroscopy (GFAAS) following digestion with nitric\\ud acid and hydrogen peroxide. Large intra-batch variations were found as expected for tablets produced\\ud in clandestine laboratories. For example, nickel in batch 1 was present in the range 0.47-13.1 ppm and\\ud in batch 2 in the range 0.35-9.06 ppm. Although batch 1 had significantly high...

Surface properties of Co-doped BaFe{sub 2}As{sub 2} thin films deposited on MgO with Fe buffer layer and CaF{sub 2} substrates

Energy Technology Data Exchange (ETDEWEB)

Sobota, R. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Plecenik, T., E-mail: tomas.plecenik@fmph.uniba.sk [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Gregor, M.; Truchly, M.; Satrapinskyy, L.; Vidis, M.; Secianska, K. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Kurth, F.; Holzapfel, B.; Iida, K. [Institute for Metallic Materials, IFW Dresden, PO Box 270116, D-01171 Dresden (Germany); Kus, P.; Plecenik, A. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia)

2014-09-01

Highlights: • Surfaces of Co-doped Ba-122 films on various substrates were studied. • Substrate influences topography and surface conductivity distribution of the films. • Surface conductivity of Co-doped Ba-122 is highly inhomogeneous. • Point contact spectroscopy results can be affected by the surface differences. - Abstract: Surface properties of Co-doped BaFe{sub 2}As{sub 2} (Ba-122) thin films prepared by pulsed laser deposition on MgO with Fe buffer layer and CaF{sub 2} substrates were inspected by atomic force microscopy, scanning spreading resistance microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, auger electron spectroscopy/microscopy and point contact spectroscopy (PCS). Selected PCS spectra were fitted by extended 1D BTK model. The measurements were done on as-received as well as ion beam etched surfaces. Our results show that the substrate is considerably influencing the surface properties of the films, particularly the topography and surface conductivity distribution, what can affect results obtained by surface-sensitive techniques like PCS.

Revisiting the BaO2/BaO redox cycle for solar thermochemical energy storage.

Science.gov (United States)

Carrillo, A J; Sastre, D; Serrano, D P; Pizarro, P; Coronado, J M

2016-03-21

The barium peroxide-based redox cycle was proposed in the late 1970s as a thermochemical energy storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction-oxidation reactions of the BaO2/BaO system for thermochemical heat storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge-discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar thermochemical heat storage.

Synthesis and characterization of BaTiO3 ferroelectric material

International Nuclear Information System (INIS)

Osman, K.I.

2011-01-01

BaTiO 3 powder was prepared at low temperatures using the solid-state reaction, starting with two different precursors; the BaCO 3 /TiO 2 and the Ba(NO 3 ) 2 /TiO 2 powder mixtures. It was found that, a single phase BaTiO 3 was formed after calcination at 750 degree C for 10 h and at 600 degree C for 6 h for the first and second mixtures, respectively. Thermal and XRD analyses were used to study the formation kinetics of BaTiO 3 . Contracting volume reaction model was found to control both reactions. The SEM of the as milled powder, TMA, TG and thermodynamics analysis have been used to propose a realistic approach describing the reaction mechanism of BaTiO 3 . Characterization and the dielectric properties of the sintered BaTiO 3 were investigated. The relative permittivity and the dielectric loss measured at room temperature and at 1 khz were 2028.5 and 0.043 for BaTiO 3 prepared from BaCO 3 /TiO 2 , while they were 1805.33 and 0.41 for BaTiO 3 prepared from Ba(NO 3 ) 2 /TiO 2 .

Measurement of Apparent Temperature in Post-Detonation Fireballs Using Atomic Emission Spectroscopy

Science.gov (United States)

2011-02-01

thermometric species into burners.3,12 Interestingly, Wilkin- son et al.6 have recently observed Al atomic emission lines in the spectrum of aluminum...candidate thermometric species must produce several strong emission lines in the spectrum that originate from different upper energy levels in order to...allow the populations of the associated states to be determined. Barium nitrate was chosen as a thermometric impurity for the current work since Ba

Electron density distribution in BaPb1−xSbxO3 superconducting oxides studied by double nuclear magnetic resonance methods

International Nuclear Information System (INIS)

Piskunov, Yu. V.; Ogloblichev, V. V.; Arapova, I. Yu.; Sadykov, A. V.; Gerashchenko, A. P.; Verkhovskii, S. V.

2011-01-01

The effect of charge disorder on the formation of an inhomogeneous state of the electron system in the conduction band in BaPb 1−x Sb x O 3 superconducting oxides is investigated experimentally by NMR methods. The NMR spectra of 17 O are measured systematically, and the contributions from 17 O atoms with different cation nearest surroundings are identified. It is found that microscopic regions with an elevated spin density of charge carriers are formed within two coordination spheres near antimony ions. Nuclei of the superconducting phase of the oxide (regions with an elevated antimony concentration) microscopically distributed over the sample are detected in compounds with x = 0.25 and 0.33. Experiments in which a double resonance signal of the spin echo of 17 O- 207 Pb and 17 O- 121 Sb are measured in the metal phase of BaPb 1−x Sb x O 3 oxides are carried out for the first time. The constants of indirect heteronuclear spin-spin 17 O- 207 Pb interaction are determined as functions of the local Knight shift 207 Ks. The estimates of the constants of the indirect interaction between the nuclei of the nearest neighbors (O-Pb and Pb-Pb atoms) and analysis of evolution of the NMR spectra of 17 O upon a change in the antimony concentration are convincing evidence in favor of the development of a microscopically inhomogeneous state of the electron system in the metal phase of BaPb 1−x Sb x O 3 oxides.

Experimental investigation of decay properties of neutron deficient $^{116-118}$Ba isotopes and test of $^{112-115}$Ba beam counts

CERN Multimedia

We propose to study decay of neutron deficient isotopes $^{116-118}$Ba using Double Sided Silicon Strip Detector (DSSSD). To study delayed-proton and $\\alpha$-decay branching ratios of $^{116-118}$Ba are of special interest because of their vicinity to the proton drip line. The nuclear life-times and properties of the proton unstable states of Cs isotopes, populated through decay of $^{116-118}$Ba isotopes will be measured. In addition to that we propose beam development of $^{112-115}$Ba to study exotic decay properties of these neutron deficient nuclei and to search for super-allowed $\\alpha$-decay in future.

Thermoelectric power factor of La0.9M0.1FeO3 (M = Ca and Ba) system: Structural, band gap and electrical transport evaluations

Science.gov (United States)

Karthikeyan, N.; Kumar, R. Ramesh; Jaiganesh, G.; Sivakumar, K.

2018-01-01

The search for thermoelectric materials has been incredibly increased due to the increase in global energy demand. Hence the present work focus on preparation and characterization of thermal transport phenomena of pure and Ba/Ca substituted perovskite LaFeO3 orthoferrite system. The conventional solid state reaction technique is utilized for the preparation of LaFeO3 and La0.9M0.1FeO3 (M = Ca and Ba) compounds. Crystal structure analyses of the prepared samples are analyses using Rietveld refinement process which confirms the orthoferrite crystal structure of all the prepared compounds with induced distortion in position of atoms by the incorporation of substituent atoms. The electronic structure calculations are performed by VASP. As the LaFeO3 compound is a strongly energy correlated system, the Density Functional Theory (DFT) calculations are performed by DFT + U (Hubbard function) method. The computed band gap values are compared with the energy gap values calculated from UV-Vis spectral analysis. Electrical conductivity measurement and Arrhenius behavior for the temperature range of room temperature to 650 K are analyzed and the drift increase in conductivity with respect to temperature is due to the thermally activated mobility of charge carriers. Temperature dependent thermopower analysis is also examined using homemade seebeck coefficient measurement system. The calculation of thermoelectric power factor reveals that the Ba substituted LaFeO3 compound show highest power factor value of 3.73 μW/K2 cm at higher temperature and the superior power factor values observed in the Ba substituted compound determine the material's capability in power generating devices based on thermoelectric effect.

Enhanced 77 K vortex-pinning in Y Ba2Cu3O7−x films with Ba2Y TaO6 and mixed Ba2Y TaO6 + Ba2Y NbO6 nano-columnar inclusions with irreversibility field to 11 T

Directory of Open Access Journals (Sweden)

F. Rizzo

2016-06-01

Full Text Available Pulsed laser deposited thin Y Ba2Cu3O7−x (YBCO films with pinning additions of 5 at. % Ba2Y TaO6 (BYTO were compared to films with 2.5 at. % Ba2Y TaO6 + 2.5 at. % Ba2Y NbO6 (BYNTO additions. Excellent magnetic flux-pinning at 77 K was obtained with remarkably high irreversibility fields greater than 10 T (YBCO-BYTO and 11 T (YBCO-BYNTO, representing the highest ever achieved values in YBCO films.

(Ba+Sr)/Ti ratio dependence of the dielectric properties for (Ba0.5Sr0.5)TiO3 thin films prepared by ion beam sputtering

Science.gov (United States)

Yamamichi, Shintaro; Yabuta, Hisato; Sakuma, Toshiyuki; Miyasaka, Yoichi

1994-03-01

(Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from powder targets with (Ba+Sr)/Ti ratios ranging from 0.80 to 1.50. All of the perovskite (Ba,Sr)TiO3 films were single phase except for the film with a (Ba+Sr)/Ti ratio of 1.41. The dielectric constant values notably depended on the (Ba+Sr)/Ti ratio for films thicker than 70 nm. The highest dielectric constant of 580 was achieved for the 5% (Ba+Sr) rich film. This (Ba+Sr)/Ti ratio dependence was diminished by the thickness dependence for thinner films. The grain sizes for the 9% (Ba+Sr) rich film and for the 6% (Ba+Sr) poor film ranged from 70 to 100 nm and from 30 to 60 nm, respectively. This grain size difference could explain why slightly A-site rich (Ba,Sr)TiO3 films have a larger dielectric constant than A-site poor films.

Structural and thermodynamic characterization of the perovskite-related BA{sub 1+y}UO{sub 3+x} and (BA,SR){sub 1+y}UO{sub 3+x} phases

Energy Technology Data Exchange (ETDEWEB)

Cordfunke, E.H.P. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Booij, A.S. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Smit-Groen, V. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Vlaanderen, P. van [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); IJdo, D.J.W. [Rijksuniversiteit Leiden (Netherlands). Gorlaeus Labs.

1996-11-01

The perovskite-type BaUO{sub 3} structure has been investigated by X-ray and neutron diffraction. The Ba/U ratio, the (Ba, Sr)/U ratio, and the oxygen stoichiometry in Ba{sub 1+y}UO{sub 3+x} were varied, and the integral enthalpies of formation determined by solution calorimetry. In addition, equilibrium oxygen partial pressures were measured using a reversible EMF cell. The chemical defect mechanism is discussed, and it is shown that a continuous series BaUO{sub 3}-Ba{sub 1+y}UO{sub 3+x}-Ba{sub 3}UO{sub 6} exist in which uranium vacancies are gradually filled up with barium ions, whereas uranium is oxidized via the pentavalent to the hexavalent state in Ba{sub 3}UO{sub 6}(=Ba{sub 2}(Ba, U)O{sub 6}). (orig.).

Dynamics of photoexcited Ba+ cations in 4He nanodroplets

International Nuclear Information System (INIS)

2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Leal, Antonio; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Pi, Martí; Zhang, Xiaohang; Drabbels, Marcel; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" >Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo

2016-01-01

We present a joint experimental and theoretical study on the desolvation of Ba + cations in 4 He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba + cations and Ba + He n exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba + He n exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba + . In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba + cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba + cations or exciplexes, even when relaxation pathways to lower lying states are included.

Fluorescent atom coincidence spectroscopy of extremely neutron-deficient barium isotopes

International Nuclear Information System (INIS)

Wells, S.A.; Evans, D.E.; Griffith, J.A.R.; Eastham, D.A.; Groves, J.; Smith, J.R.H.; Tolfree, D.W.L.; Warner, D.D.; Billowes, J.; Grant, I.S.; Walker, P.M.

1988-01-01

Fluorescent atom coincidence spectroscopy (FACS) has been used to measure the nuclear mean square radii and moments of the extremely neutron-deficient isotopes 120-124 Ba. At N=65 an abrupt change in nuclear mean square charge radii is observed which can be understood in terms of the occupation of the spin-orbit partner g 7/2 5/2[413] neutron and g 9/2 9/2[404] proton orbitals and the consequent enhancement of the n-p interaction. (orig.)

The interaction of NO2 with BaO: from cooperative adsorption to Ba(NO3)2 formation

International Nuclear Information System (INIS)

Yi, Cheol-Woo W.; Kwak, Ja Hun H.; Szanyi, Janos

2007-01-01

The effect of water on the morphology of BaO/Al2O3-based NOx storage materials was investigated using Fourier transform infrared spectroscopy, temperature programmed desorption, and time-resolved synchrotron X-ray diffraction techniques. The results of this multi-spectroscopy study reveal that, in the presence of water, surface Ba-nitrates convert to bulk nitrates, and water facilitates the formation of large Ba(NO3)2 particles. The conversion of surface to bulk Ba-nitrates is completely reversible, i.e. after the removal of water from the storage material a significant fraction of the bulk nitrates re-convert to surface nitrates. NO2 exposure of a H2O-containing (wet) BaO/Al2O3 sample results in the formation of nitrites and bulk nitrates exclusively, i.e. no surface nitrates form. After further exposure to NO2, the nitrites completely convert to bulk nitrates. The amount of NOx taken up by the storage material is, however, essentially unaffected by the presence of water, regardless of whether the water was dosed prior to or after NO2 exposure. Based on the results of this study we are now able to explain most of the observations reported in the literature on the effect of water on NOx uptake on similar storage materials

Ab initio hybrid DFT calculations of BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces

Energy Technology Data Exchange (ETDEWEB)

Eglitis, Roberts I., E-mail: rieglitis@gmail.com

2015-12-15

Highlights: • Surface energies for AO{sub 3}-term (111) surfaces are larger than for Ti (Zr)-term surfaces. • A increase of Ti−O (Zr−O) bond covalency near the ABO{sub 3} (111) surface relative to the bulk is observed. • The ABO{sub 3} (111) surface energy is larger than the earlier calculated (001) surface energy. • Band gap for PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces becomes smaller, but for BaTiO{sub 3} (111) larger with respect to the bulk . - Abstract: The results of ab initio calculations for polar BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces using the CRYSTAL code are presented. By means of the hybrid B3LYP approach, the surface relaxation has been calculated for two possible B (B = Ti or Zr) or AO{sub 3} (A = Ba, Pb or Sr) BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface terminations. According to performed B3LYP calculations, all atoms of the first surface layer, for both terminations, relax inwards. The only exception is a small outward relaxation of the PbO{sub 3}-terminated PbTiO{sub 3} (111) surface upper layer Pb atom. B3LYP calculated surface energies for BaO{sub 3}, PbO{sub 3}, SrO{sub 3} and PbO{sub 3}-terminated BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are considerably larger than the surface energies for Ti (Zr)-terminated (111) surfaces. Performed B3LYP calculations indicate a considerable increase of Ti−O (Zr−O) chemical bond covalency near the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface relative to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk. Calculated band gaps at the Γ-point near the PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are reduced, but near BaTiO{sub 3} (111) surfaces increased, with respect to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk band gap at the Γ-point values.

Growth of BaSi2 continuous films on Ge(111) by molecular beam epitaxy and fabrication of p-BaSi2/n-Ge heterojunction solar cells

Science.gov (United States)

Takabe, Ryota; Yachi, Suguru; Tsukahara, Daichi; Toko, Kaoru; Suemasu, Takashi

2017-05-01

We grew BaSi2 films on Ge(111) substrates by various growth methods based on molecular beam epitaxy (MBE). First, we attempted to form BaSi2 films directly on Ge(111) by MBE without templates. We next formed BaSi2 films using BaGe2 templates as commonly used for MBE growth of BaSi2 on Si substrates. Contrary to our prediction, the lateral growth of BaSi2 was not promoted by these two methods; BaSi2 formed not into a continuous film but into islands. Although streaky patterns of reflection high-energy electron diffraction were observed inside the growth chamber, no X-ray diffraction lines of BaSi2 were observed in samples taken out from the growth chamber. Such BaSi2 islands were easily to get oxidized. We finally attempted to form a continuous BaSi2 template layer on Ge(111) by solid phase epitaxy, that is, the deposition of amorphous Ba-Si layers onto MBE-grown BaSi2 epitaxial islands, followed by post annealing. We achieved the formation of an approximately 5-nm-thick BaSi2 continuous layer by this method. Using this BaSi2 layer as a template, we succeeded in forming a-axis-oriented 520-nm-thick BaSi2 epitaxial films on Ge substrates, although (111)-oriented Si grains were included in the grown layer. We next formed a B-doped p-BaSi2(20 nm)/n-Ge(111) heterojunction solar cell. A wide-spectrum response from 400 to 2000 nm was achieved. At an external bias voltage of 1 V, the external quantum efficiency reached as high as 60%, demonstrating the great potential of BaSi2/Ge combination. However, the efficiency of a solar cell under AM1.5 illumination was quite low (0.1%). The origin of such a low efficiency was examined.

Complex refractive index measurements for BaF 2 and CaF 2 via single-angle infrared reflectance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kelly-Gorham, Molly Rose K.; DeVetter, Brent M.; Brauer, Carolyn S.; Cannon, Bret D.; Burton, Sarah D.; Bliss, Mary; Johnson, Timothy J.; Myers, Tanya L.

2017-10-01

We have re-investigated the optical constants n and k for the homologous series of inorganic salts barium fluoride (BaF2) and calcium fluoride (CaF2) using a single-angle near-normal incidence reflectance device in combination with a calibrated Fourier transform infrared (FTIR) spectrometer. Our results are in good qualitative agreement with most previous works. However, certain features of the previously published data near the reststrahlen band exhibit distinct differences in spectral characteristics. Notably, our measurements of BaF2 do not include a spectral feature in the ~250 cm-1 reststrahlen band that was previously published. Additionally, CaF2 exhibits a distinct wavelength shift relative to the model derived from previously published data. We confirmed our results with recently published works that use significantly more modern instrumentation and data reduction techniques

Manipulating the ferroelectric polarization state of BaTiO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Datta, S.; Rioult, M.; Stanescu, D.; Magnan, H.; Barbier, A., E-mail: antoine.barbier@cea.fr

2016-05-31

Controlling the ferroelectric polarization at macroscopic or microscopic levels is crucial in the framework of the development of ferroelectric materials used in yet challenging photo-electrochemical (PEC) cells and spintronic applications. We report here on polarization methods allowing to electrically polarize prototypical samples of BaTiO{sub 3} (001) films. Epitaxial single crystalline layers were grown up to a thickness of 25 nm by atomic oxygen assisted molecular beam epitaxy on 1 at.% Nb doped SrTiO{sub 3} (001) single crystals. The samples were both microscopically and macroscopically polarized using Piezoresponse Force Microscopy and electrochemical poling in an electrolyte respectively. In addition we demonstrate the possibility to retrieve a quasi-native mixed ferroelectric polarization state after annealing. These polarization methods may be applied to many other ferroelectric thin films. - Highlights: • Ferroelectricity of BaTiO{sub 3} layers can be micro- and macroscopically controlled. • Microscopic ferroelectric domains are defined with piezoresponse force microscopy. • Poling in a LiClO{sub 4} electrolyte is a macroscopic poling method. • Air annealing above the Curie temperature “resets” the polarization state.

Chemical reaction between single hydrogen atom and graphene

International Nuclear Information System (INIS)

Ito, Atsushi; Nakamura, Hiroaki; Takayama, Arimichi

2007-04-01

We study chemical reaction between a single hydrogen atom and a graphene, which is the elemental reaction between hydrogen and graphitic carbon materials. In the present work, classical molecular dynamics simulation is used with modified Brenner's empirical bond order potential. The three reactions, that is, absorption reaction, reflection reaction and penetration reaction, are observed in our simulation. Reaction rates depend on the incident energy of the hydrogen atom and the graphene temperature. The dependence can be explained by the following mechanisms: (1) The hydrogen atom receives repulsive force by π-electrons in addition to nuclear repulsion. (2) Absorbing the hydrogen atom, the graphene transforms its structure to the 'overhand' configuration such as sp 3 state. (3) The hexagonal hole of the graphene is expanded during the penetration of the hydrogen atom. (author)

Temperature dependent XAFS studies of local atomic structure of the perovskite-type zirconates

International Nuclear Information System (INIS)

Vedrinskii, R. V.; Lemeshko, M. P.; Novakovich, A. A.; Nazarenko, E. S.; Nassif, V.; Proux, O.; Joly, Y.

2006-01-01

Temperature dependent preedge and extended x-ray absorption fine structure measurements at the Zr K edge for the perovskite-type zirconates PbZr 0.515 Ti 0.485 O 3 (PZT), PbZrO 3 (PZ), and BaZrO 3 are performed. To carry out a more accurate study of the weak reconstruction of the local atomic structure we employed a combination of two techniques: (i) analysis of the preedge fine structure, and (ii) analysis of the Fourier transform of the difference between χ(k) functions obtained at different temperatures. A detailed investigation of local atomic structure in the cubic phase for all the crystals is also performed. It is shown that neither the displacive nor the order-disorder model can describe correctly the changes of local atomic structure during phase transitions in PZ and PZT. A spherical model describing the local atomic structure of perovskite-type crystals suffering structural phase transitions is proposed

Interface effects on the electronic transport properties in highly epitaxial LaBaCo2O(5.5+δ) films.

Science.gov (United States)

Ma, C R; Liu, M; Liu, J; Collins, G; Zhang, Y M; Wang, H B; Chen, C L; Lin, Y; He, J; Jiang, J C; Meletis, E I; Jacobson, A J

2014-02-26

Single-crystalline perovskite LaBaCo2O5.5+δ thin films were grown on a (110) NdGaO3 single-crystal substrate in order to systematically investigate the effect of lattice mismatch on the electrical transport properties in comparison to the films on LaAlO3, SrTiO3, and MgO substrates. Microstructure studies reveal that all of the LaBaCo2O5.5+δ films are of excellent quality with atomically sharp interface structures. The electrical and magnetic transport property studies indicate that the resistivity, magnetoresistance, and magnetic moment of the film are very sensitive to the substrate materials because of the lattice mismatch/interface strain. The Curie temperature, however, is almost independent of the strain imposed by the substrate, probably because of the strong coupling between the nanodomain boundary and interface strain.

Excitation-dependent local symmetry reversal in single host lattice Ba2A(BO3)2:Eu3+ [A = Mg and Ca] phosphors with tunable emission colours.

Science.gov (United States)

Jayakiruba, S; Chandrasekaran, S Selva; Murugan, P; Lakshminarasimhan, N

2017-07-05

Eu 3+ activated phosphors are widely used as red emitters in various display devices and light emitting diodes (LEDs). The emission characteristics of Eu 3+ depend on the local site symmetry. The present study demonstrates the role of excitation-dependent local symmetry changes due to the structural reorganization on the emission colour tuning of Eu 3+ from orange-red to orange in single host lattices, Ba 2 Mg(BO 3 ) 2 and Ba 2 Ca(BO 3 ) 2 . The choice of these lattices was based on the difference in the extent of strain experienced by the oxygen atoms. The samples with Eu 3+ at Ba or Mg (Ca) sites were synthesized using the conventional high-temperature solid-state reaction method. The samples were characterized using powder XRD, 11 B MAS-NMR, FT-IR, and diffuse reflectance UV-Vis spectroscopic techniques. The room temperature photoluminescence (PL) recorded using different excitation wavelengths revealed a clear difference in the PL emission features due to symmetry reversal from non-inversion to inversion symmetry around Eu 3+ . The reorganization of highly strained oxygen atoms leads to such symmetry reversal. First-principles calculations were used to deduce the optimized structures of the two borate host lattices, and local geometries and their distortions upon Eu 3+ substitution. The outcomes of these calculations support the experimental findings.

Elastic properties of nano structured AZrO3 (A=Ba, Sr) single perovskites

International Nuclear Information System (INIS)

Pazhani, R.; Thomas, J.K.; Moses Ezhil Raj, A.; Solomon, S.; Bena Jothy, V.; Mathai, K.C.

2011-01-01

Nanocrystals of barium zirconate and strontium zirconate AZrO 3 (A=Ba and Sr) were synthesized by a unique self-sustained single-step combustion of an aqueous solution, containing Ba, Sr and Zr ions by using citric acid as complexing agent and liquor ammonia as fuel, thus giving rise to phase pure AZrO 3 nanopowder. In this process, a single phase pure nanopowder of AZrO 3 has been obtained without the need of calcination steps. The formation and stability of the compound was confirmed through the tolerance factor on the basis of the ionic radii of all the atoms of the compound. Phase-purity of the as-prepared powders was examined using X-ray diffraction. As-prepared powder was single phase, crystalline, and composed of uniform particles with sizes 20-30 nm. The crystal structure of AZrO 3 are respective cubic (Pm3-bar m, a=4.1839A) and orthorhombic (Pnma, a=5.7937A, b=8.17648A and c=5.7694A). Annealed samples of SrZrO 3 has improved crystal structure with a=5.764A, b=8.2292A and c=5.7989A, comparable to the standards. Microstrain acting on all the planes of the material is positive which indicates presence of tensile stress on the material. The calculated compressive stress on the surface of' the nanopowder is of the order 0.213 GPa to -0.274 GPa for BaZrO 3 and 4.443 GPa to -0.220 GPa for SrZrO 3 along various planes of the particles. (author)

Decrease in electrical contact resistance of Sb-doped n+-BaSi2 layers and spectral response of an Sb-doped n+-BaSi2/undoped BaSi2 structure for solar cells

Science.gov (United States)

Kodama, Komomo; Takabe, Ryota; Yachi, Suguru; Toko, Kaoru; Suemasu, Takashi

2018-03-01

We investigated how the electron concentration n in a 300-nm-thick Sb-doped n+-BaSi2 layer grown by molecular beam epitaxy affected the contact resistance R C to surface electrodes (Al, indium-tin-oxide). As the n of n-BaSi2 increased, R C decreased and reached a minimum of 0.019 Ω cm2 at n = 2.4 × 1018 cm-3 for the Al electrodes. This value was more than 1 order of magnitude smaller than that obtained for Al/B-doped p-BaSi2. We believe that this significant decrease in R C came from Sb segregation. Furthermore, the internal quantum efficiency (IQE) spectrum was evaluated for an Sb-doped n+-BaSi2 (20 nm)/undoped BaSi2 (500 nm)/n+-Si(111) structure. Its IQE reached as high as ˜50% over a wide wavelength range under a small bias voltage of 0.1 V applied between the top and bottom electrodes.

Phase relationships in the BaO-Ga2O3-Ta2O5 system and the structure of Ba6Ga21TaO40.

Science.gov (United States)

Cao, Jiang; Yu, Xiaodi; Kuang, Xiaojun; Su, Qiang

2012-07-16

Phase relationships in the BaO-Ga(2)O(3)-Ta(2)O(5) ternary system at 1200 °C were determined. The A(6)B(10)O(30) tetragonal tungsten bronze (TTB) related solution in the BaO-Ta(2)O(5) subsystem dissolved up to ~11 mol % Ga(2)O(3), forming a ternary trapezoid-shaped TTB-related solid solution region defined by the BaTa(2)O(6), Ba(1.1)Ta(5)O(13.6), Ba(1.58)Ga(0.92)Ta(4.08)O(13.16), and Ba(6)GaTa(9)O(30) compositions in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Two ternary phases Ba(6)Ga(21)TaO(40) and eight-layer twinned hexagonal perovskite solid solution Ba(8)Ga(4-x)Ta(4+0.6x)O(24) were confirmed in the BaO-Ga(2)O(3)-Ta(2)O(5) system. Ba(6)Ga(21)TaO(40) crystallized in a monoclinic cell of a = 15.9130(2) Å, b = 11.7309(1) Å, c = 5.13593(6) Å, β = 107.7893(9)°, and Z = 1 in space group C2/m. The structure of Ba(6)Ga(21)TaO(40) was solved by the charge flipping method, and it represents a three-dimensional (3D) mixed GaO(4) tetrahedral and GaO(6)/TaO(6) octahedral framework, forming mixed 1D 5/6-fold tunnels that accommodate the Ba cations along the c axis. The electrical property of Ba(6)Ga(21)TaO(40) was characterized by using ac impedance spectroscopy.

About effect of the Ramsauer-Townsend type at scattering of relativistic electrons by crystal atomic string

International Nuclear Information System (INIS)

Shul'ga, N.F.; Truten', V.I.

1999-01-01

It is shown that a considerable decrease in a total cross-section of the elastic scattering of relativistic electrons by a crystal atomic string can take place at certain values of particle incidence angles. This effect is similar to the Ramsauer-Townsend effect of slow electrons scattering by an atom. It is shown that the decrease in the angle of particles incidence on the atomic string essentially changes the process of particles scattering. The phenomena of the particle rainbow scattering and orbiting may occur in this case. 14 refs., 5 figs

Studying atomic-resolution by X-ray fluorescence holography

International Nuclear Information System (INIS)

Gao Hongyi; Chen Jianwen; Xie Honglan; Zhu Huafeng; Li Ruxin; Xu Zhizhan

2005-01-01

In this work, the results of numerical simulations of X-ray fluorescence holograms and the reconstructed atomic images for Fe single crystal are given. The influences of the recording angles ranges and the polarization effect on the reconstruction of the atomic images are discussed. The process for removing twin images by multiple energy fluorescence holography and expanding the energy range of the incident X-rays to improve the resolution of the reconstructed images is presented

Study of the incident pion deflection in passing through atomic nucleus

International Nuclear Information System (INIS)

Strugalski, Z.; Pawlak, T.; Pluta, J.

1982-01-01

Pion-xenon nucleus collision events at 3.5 GeV/c momentum are studied in which the incident pion is deflected only, without particle production; the deflection is accompanied by emission of nucleons. The multiplicity of the protons emitted is a measure of the nuclear matter layer thickness passed by the pion. It can be concluded that: a) a definite simple relation exists between the pion deflection angle and the thickness of the nuclear matter layer traversed by this pion; b) the deflection angle of the incident pion increases in a definite manner with increasing the thickness of the nuclear matter layer traversed by this pion; c) the average kinetic energy, average longitudinal momentum and average transverse momentum of the protons emitted do not depend on the pion deflection angle

Barium atoms and N20 molecular agregates reaction

International Nuclear Information System (INIS)

Visticot, J.P.; Mestdagh, J.M.; Alcaraz, C.; Cuvellier, J.; Berlande, J.

1988-06-01

The collisions between a barium atom and N20 molecular agregates are studied, for a better understanding of the solvation part in a chemical reaction. The experiments are carried out in a crossed molecular beam device. The light coming from the collision zone is scattered, and analysed by means of a photon detector. A time-of-flight technique is applied in the investigation of the beam's polymer concentration. The results show a nearly negligible chemiluminescent effect in the reaction between barium and N20 polymer. A solvated BaO formation mechanism is proposed to justify the experimental results [fr

Ruthenium perovskites of type Ba/sub 2/BRuO/sub 6/ and Ba/sub 3/BRu/sub 2/O/sub 9/ with B = indium, rhodium

Energy Technology Data Exchange (ETDEWEB)

Schaller, H U; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1981-02-01

The black perovskites Ba/sub 2/InRu/sup 5 +/O/sub 6/ and Ba/sub 3/InRu/sub 2/O/sub 9/ (mean oxydation state of ruthenium: +4.5) adopt the hexagonal BaTiO/sub 3/ structure and form a continuous series of mixed crystals. According to the intensity calculations and analysis of the vibrational spectroscopic data an ordered distribution between indium and ruthenium is present: 1:1 order in Ba/sub 2/RuO/sub 6/ (space group P-3m1 respective Dsub(3d)/sup 3/; R' = 5.3%); 1:2 order in Ba/sub 3/InRu/sub 2/O/sub 9/ (space group P6/sub 3//mmc respective Dsub(6h)/sup 4/; R' = 4.6%). The corresponding black Rh compounds, Ba/sub 2/RhRuO/sub 6/ and Ba/sub 3/RhRu/sub 2/O/sub 9/, crystallize in the rhombohedral 9 L type of BaRuO/sub 3/ (author).

Scintillation and radiation damage of doped BaF2 crystals

International Nuclear Information System (INIS)

Gong Zufang; Xu Zizong; Chang Jin

1992-01-01

The emission spectra and the radiation damage of BaF 2 crystals doped Ce and Dy have been studied. The results indicate that the doped BaF 2 crystals have the intrinsic spectra of impurity besides the intrinsic spectra of BaF 2 crystals. The crystals colored and the transmissions decrease with the concentration of impurity in BaF 2 crystals after radiation by γ-ray of 60 Co. The doped Ce BaF 2 irradiated by ultraviolet has faster recover of transmissions but for doped Dy the effect is not obvious. The radiation resistance is not good as pure BaF 2 crystals

A versatile atomic number correction for electron-probe microanalysis

International Nuclear Information System (INIS)

Love, G.; Cox, M.G.; Scott, V.D.

1978-01-01

A new atomic number correction is proposed for quantitative electron-probe microanalysis. Analytical expressions for the stopping power S and back-scatter R factors are derived which take into account atomic number of the target, incident electron energy and overvoltage; the latter expression is established using Monte Carlo calculations. The correct procedures for evaluating S and R for multi-element specimens are described. The new method, which overcomes some limitations inherent in earlier atomic number corrections, may readily be used where specimens are inclined to the electron beam. (author)

Study of the effects of additives on structural properties of the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} hexaferrite; Estudo do efeito de aditivos nas propriedades estruturais da hexaferrita Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19}

Energy Technology Data Exchange (ETDEWEB)

Alves, Y.S.; Pereira, C.A.; Farias, F.C.; Mello, P.S.; Alves, A.G.; Pereira, F.M.; Barroso, M.B., E-mail: yuri.link2@gmail.com [Universidade Federal do Cariri (UFCA), Juazeiro do Norte, CE (Brazil); Saraiva, I.R.; Conde, W.S. [DeVry Fanor, Fortaleza, CE (Brazil); Sombra, A.B. [Laboratorio de Telecomunicacoes e Ciencia e Engenharia de Materiais (LOCEM/UFC), Fortaleza, CE (Brazil)

2016-07-01

The Hexaferrites are magnetic ceramic materials chemically and thermally stable, low-cost and easy processing. The objective of this work was to study the effects of SiO2 and CaO additives on structural properties of hexaferrite Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19}. The samples were characterized by scanning electron microscopy (SEM), X-Ray Diffraction (XRD) and quantified by the Rietveld method. The doped samples showed no structural change. With the concentration of dopant employed, there was a decrease in the sintering temperature of all samples Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} 1100 °C/5h to 1000 °C/2h. After addition of dopants, it was observed that the growth of the grains in the samples did not occur uniformly. This uneven growth can is being influenced by the concentrations of Ba and Sr atoms present in the samples, as well as some sort of reaction with the dopant elements. (author)

Intershell interaction in excited atom and ion photoionization

International Nuclear Information System (INIS)

Amusia, M.Ya.; Avdonina, N.B.

1989-01-01

It is demonstrated, that the photoionization cross section of an excited electron in Cs atom isoelectronic sequence acquire additional structure if the virtual polarization of the core by the incident photon is taken into account. (orig.)

Determination of incident angle in radioisotope-excited EDXRF

Energy Technology Data Exchange (ETDEWEB)

Somogyi, A.; Pazsit, A. (Lajos Kossuth Univ., Debrecen (Hungary). Isotope Lab.)

Three different methods were used for the determination of the effective incident angle related to EDXRF when radioisotope annular sources are involved: weighted averaging, Compton peak method and minimization of the difference between the certificated and measured concentrations of six international standard samples. By measuring the Compton peak energies of various analytical reagent grade elements and compounds, it was found that the incoherent peak energy depends on the mean atomic number of the matrix, so the effective incident angle is also matrix dependent. (Author).

Determination of incident angle in radioisotope-excited EDXRF

International Nuclear Information System (INIS)

Somogyi, A.; Pazsit, A.

1993-01-01

Three different methods were used for the determination of the effective incident angle related to EDXRF when radioisotope annular sources are involved: weighted averaging, Compton peak method and minimization of the difference between the certificated and measured concentrations of six international standard samples. By measuring the Compton peak energies of various analytical reagent grade elements and compounds, it was found that the incoherent peak energy depends on the mean atomic number of the matrix, so the effective incident angle is also matrix dependent. (Author)

Chemiluminescence from the reaction of Ba 3D with nitric oxide

International Nuclear Information System (INIS)

Johnson, S.A.; Solarz, R.W.; Dubrin, J.W.; Brotzmann, R.

1977-01-01

The reaction of laser excited Ba*( 3 D) states with nitric oxide is presented. BaO product is not detected, although the channel is thermodynamically open, and instead chemiluminescence is observed. Experiments which suggest that radiative recombination, Ba + NO → BaNO* → BaNO, is the observed reaction channel will also be presented

On ternary intermetallic aurides. CaAu{sub 2}Al{sub 2}, SrAu{sub 2-x}Al{sub 2+x} and Ba{sub 3}Au{sub 5+x}Al{sub 6-x}

Energy Technology Data Exchange (ETDEWEB)

Stegemann, Frank [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Benndorf, Christopher [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Mineralogie, Kristallographie und Materialwissenschaften, Universitaet Leipzig (Germany); Zhang, Yuemei; Fokwa, Boniface P.T. [Department of Chemistry, University of California, Riverside, CA (United States); Bartsch, Manfred; Zacharias, Helmut [Physikalisches Institut, Westfaelische Wilhelms-Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, Sao Carlos, SP (Brazil); Janka, Oliver [Institut fuer Anorganische und Analytische Chemie, Westfaelische Wilhelms-Universitaet Muenster (Germany); Institut fuer Chemie, Carl von Ossietzky Universitaet Oldenburg (Germany)

2017-11-17

The intermetallic compound CaAu{sub 2}Al{sub 2}, and the members of the solid solutions SrAu{sub 2-x}Al{sub 2+x} (0 ≤ x ≤ 0.33) and Ba{sub 3}Au{sub 5+x}Al{sub 6-x} (x = 0, 0.14, 0.49) were synthesized from the elements in sealed tantalum ampoules. The Ca compound crystallizes with the orthorhombic ThRu{sub 2}P{sub 2} type structure, whereas the targeted SrAu{sub 2}Al{sub 2} was found to form a solid solution according to SrAu{sub 2-x}Al{sub 2+x}. For the Ba system no ''BaAu{sub 2}Al{sub 2}'' was found, however, Ba{sub 3}Au{sub 5+x}Al{sub 6-x} was discovered to crystallize in the monoclinic space group C2/c with its own structure type. The samples were investigated by powder X-ray diffraction and their crystal structures were refined on the basis of single-crystal X-ray diffraction data. All compounds were characterized furthermore by susceptibility measurements. The crystallographic aluminum sites of CaAu{sub 2}Al{sub 2} and Ba{sub 3}Au{sub 5}Al{sub 6} can be differentiated by {sup 27}Al solid state NMR spectra on the basis of their different electric field gradients, in agreement with theoretical calculations. The electron transfer from the alkaline earth metals and the aluminum atoms onto the gold atoms was investigated by X-ray photoelectron spectroscopy (XPS) classifying these intermetallics as aurides, in full agreement with the calculated Bader charges. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Thermoelectric properties of doped BaHfO_3

International Nuclear Information System (INIS)

Dixit, Chandra Kr.; Bhamu, K. C.; Sharma, Ramesh

2016-01-01

We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO_3 by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO_3 doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO_3 is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO_3 is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

Atomic-resolution neutron holography

International Nuclear Information System (INIS)

Cser, L.; Toeroek, Gy.; Krexner, G.

2001-01-01

Atomic-resolution neutron holography can be realised by two different schemes. In the frame of the first approach a point-like source of slow neutrons is produced inside the investigated crystal. Due to the extremely large value of the incoherent-scattering cross-section of the proton, hydrogen atoms imbedded in a metal single-crystal lattice may serve as point-like sources when the sample is irradiated by a monochromatic beam of slow neutrons. The second approach utilizes the registration of the interference between the incident and scattered waves by means of a point-like detector inserted in the lattice of the crystal under investigation. In addition, neutron-induced electron holography is considered. The feasibility of these ideas is discussed. (orig.)

Structural properties and growth evolution of diamond-like carbon films with different incident energies: A molecular dynamics study

International Nuclear Information System (INIS)

Li, Xiaowei; Ke, Peiling; Zheng, He; Wang, Aiying

2013-01-01

Structural properties and growth evolution of diamond-like carbon (DLC) films with different incident energies were investigated systematically by the molecular dynamics simulation using a Tersoff interatomic potential for carbon-carbon interaction. The results revealed that the density, sp 3 fraction and residual compressive stress as a function of incident energy increased firstly and then decreased; when the incident energy was 70 eV/atom, the density could reach to 3.0 g/cm 3 with the maximal compressive stress of 15.5 GPa. Structure analysis indicated that the deviation of both bond angles and lengths from the equilibrium position led to the generation of a large residual stress, while the high compressive stress mainly attributed to the decrease of both bond angles and lengths among carbon atoms. The growth of DLC films underwent a formation process of “Line-Net” structure accompanied with the interaction of many atomic motion mechanisms, and the “Point” stage was only found for DLC films with low incident energy.

AHP 45: REVIEW: PHYUR BA

Directory of Open Access Journals (Sweden)

'Brug mo skyid འབྲུག་མོ་སྐྱིད། (Zhoumaoji 周毛吉

2017-03-01

Full Text Available Mkha' mo rgyal was born in Dgon gong ma Village, 'Ba' (Tongde County, Mtsho lho (Hainan Tibetan Autonomous Prefecture, Mtsho sngon (Qinghai Province. While attending the Tibetan Studies College of Mtsho sngon Nationalities University she began writing. In addition to editing and translating teaching materials for primary and secondary schools, she has also published short stories and poetry (Mkha' mo rgyal, 2015. Phyur ba is the first Tibetan women's novel (Robin 2016:86 and was recognized as an Outstanding Work by the Qinghai Writers Guild in 2014 (Duojiecairang and Limaoyou 2014. 1 The name, which translates as 'dried cheese' is a food eaten daily by many Tibetans. Made from fermented milk without cream, it is dried in the sun by women in pastoral areas. Both sweet and sour, phyur ba brings to mind the happiness and sadness, ups and downs, laughter and tears that life brings. ...

Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact

CERN Document Server

Chaudhry, Afzal

2011-01-01

Analysis of Excitation and Ionization of Atoms and Molecules by Electron Impact, by Afzal Chaudhry and Hans Kleinpoppen, describes in detail the measurements of the partial and total doubly differential cross sections for the multiple-ionization of rare gas atoms by electron impact. These measurements show, among other trends, the role of Auger transitions in the production of multiply ionized atoms in the region where the incident electron energy is sufficient to produce inner shell ionization. Other processes like Coster-Kronig transitions and shake off also contribute towards increasing the charge of the ions. As discussed in the book, an incident electron having energy of 6 keV, for example, in a collision with xenon atom can remove up to nine electrons! The measurements of doubly differential cross sections for the dissociative and non-dissociative ionization of hydrogen, sulfur dioxide and sulfur hexa fluoride molecular gases are also explored. The results of the measurements for the sulfur dioxide mole...

Food habits in atomic bomb survivors suffering from malignant neoplasms

International Nuclear Information System (INIS)

Morimoto, Kazue; Inoue, Hisako; Uchino, Chito

1984-01-01

Food habits were surveyed in patients admitted to 13 hospitals in Nagasaki prefecture and other prefectures to compare the incidence of malignant neoplasms according to the food intake between atomic bomb exposed group and non-exposed group. The incidence of malignant neoplasms was significantly higher in male patients having the low intake of milk and salted fish than in those having the high intake of them in atomic bomb exposed group, while it was significantly higher in male patients having the low intake of potatoes and milk and in female patients having the low intake of boiled fish paste than in those having the high intake of them in non-exposed group. (Namekawa, K.)

High-pressure BaCrO_3 polytypes and the 5H–BaCrO_2_._8 phase

International Nuclear Information System (INIS)

Arévalo-López, Angel M.; Paul Attfield, J.

2015-01-01

Polytypism of BaCrO_3 perovskites has been investigated at 900–1100 °C and pressures up to 22 GPa. Hexagonal 5H, 4H, and 6H perovskites are observed with increasing pressure, and the cubic 3C perovskite (a=3.99503(1) Å) is observed in bulk form for the first time at 19–22 GPa. An oxygen-deficient material with limiting composition 5H–BaCrO_2_._8 is synthesised at 1200 °C under ambient pressure. This contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure. - Graphical abstract: Hexagonal 5H, 4H, and 6H perovskites polytypes of BaCrO_3 are observed with increasing pressure and the cubic 3C perovskite is stabilised in bulk form for the first time at 19–22 GPa. Oxygen-deficient 5H–BaCrO_2_._8 synthesised at ambient pressure contains double tetrahedral Cr"4"+ layers and orders antiferromagnetically below 260 K with a (0 0 1/2) magnetic structure.

Facile Low Temperature Hydrothermal Synthesis of BaTiO3 Nanoparticles Studied by In Situ X-ray Diffraction

Directory of Open Access Journals (Sweden)

Ola G. Grendal

2018-06-01

Full Text Available Ferroelectric materials are crucial for today’s technological society and nanostructured ferroelectric materials are important for the downscaling of devices. Controlled and reproducible synthesis of these materials are, therefore, of immense importance. Hydrothermal synthesis is a well-established synthesis route, with a large parameter space for optimization, but a better understanding of nucleation and growth mechanisms is needed for full utilization and control. Here we use in situ X-ray diffraction to follow the nucleation and growth of BaTiO3 formed by hydrothermal synthesis using two different titanium precursors, an amorphous titania precipitate slurry and a Ti-citric acid complex solution. Sequential Rietveld refinement was used to extract the time dependency of lattice parameters, crystallite size, strain, and atomic displacement parameters. Phase pure BaTiO3 nanoparticles, 10–15 nm in size, were successfully synthesized at different temperatures (100, 125, and 150 °C from both precursors after reaction times, ranging from a few seconds to several hours. The two precursors resulted in phase pure BaTiO3 with similar final crystallite size. Finally, two different growth mechanisms were revealed, where the effect of surfactants present during hydrothermal synthesis is discussed as one of the key parameters.

Atom localization with double-cascade configuration

International Nuclear Information System (INIS)

Gordeev, Maksim Yu; Rozhdestvensky, Yuri V; Efremova, Ekaterina A

2016-01-01

We investigate the one-dimensional (1D) and two-dimensional (2D) atom localization of a four-level system in a double-cascade configuration. We demonstrate the possibility of 1D localization in the field of a standing wave, 2D localization in the field of two standing waves and 2D localization only in the field of running waves by using different configurations of driven waves on transitions. In addition, for each configuration we reached a high-precision atom localization in one of the states at scales much smaller than the wavelength of the incident optical radiation. (paper)

Biodistribution and Radiation Dosimetry of the Integrin Marker 64Cu-BaBaSar-RGD2 Determined from Whole-Body PET/CT in a Non-Human Primate

Science.gov (United States)

Liu, Shuanglong; Vorobyova, Ivetta; Park, Ryan; Conti, Peter S.

2017-10-01

Introduction: 64Cu-BaBaSar-RGD2 is a positron emission radiotracer taken up by integrin αvβ3, which is overexpressed in many malignancies. The aim of this study was to evaluate the biodistribution of 64Cu-BaBaSar-RGD2 in a non-human primate with positron emission tomography and to estimate the absorbed doses in major organs for human. Materials and methods: Whole-body PET imaging was done in a Siemens Biograph scanner in a male macaque monkey. After an i.v. injection of 13.1–19.7 MBq/kg of 64Cu-BaBaSar-RGD2, whole body scan was collected for a total duration of 180 min. Attenuation and scatter corrections were applied to reconstruction of the whole-body emission scan. After image reconstruction, three-dimensional volumes of interest (VOI) were hand-drawn on the PET transaxial or coronal slices of the frame where the organ was most conspicuous. Time-activity curves for each VOI were obtained, and residence time of each organ was calculated by integration of the time-activity curves. Human absorbed doses were estimated using the standard human model in OLINDA/EXM software. Results: Injection of 64Cu-BaBaSar-RGD2 was well tolerated in the macaque monkey, with no serious tracer-related adverse events observed. 64Cu-BaBaSar-RGD2 was cleared rapidly from the blood pool, with a 12.1-min biological half-time. Increased 64Cu-BaBaSar-RGD2 uptake was observed in the kidneys, and bladder, with mean percentage injected dose (ID%) values at 1 h after injection approximately 35.50 ± 6.47 and 36.89 ± 5.48, respectively. The calculated effective dose was 15.30 ± 2.21 µSv/MBq, and the kidneys had the highest absorbed dose at 108.43 ± 16.41 µGy/MBq using the non-voiding model. For an injected activity of 925 MBq 64Cu for human, the effective dose would be 14.2 ± 2.1 mSv. Discussion: Due to the limitation of the monkey number, we evaluated 64Cu-BaBaSar-RGD2 in the same monkey of three imaging sessions. Measured absorbed doses and effective doses of 64Cu-BaBaSar-RGD2 are

Structure of the new Tl(Ba sub 1.0 Sr sub 1.0) PrCu sub 2 O sub 7-x by Rietveld analysis

International Nuclear Information System (INIS)

Yang, P.; Fun, H. K.; Lee, T.J.; Ku, H.C.; Lai, C.C.

1994-01-01

The crystalline structure of Tl(Ba sub 1.0 Sr sub 1.0)PrCu sub 2 O sub 7-x was obtained at room temperature from x-ray powder diffraction with CuK sub α radiation using Rietveld analysis. Tl(Ba sub 1.0 Sr sub 1.0)PrCu sub 2 O sub 7-x isomorphous at both room temperature (300 K) and low temperature (100 K) with TlBa sub 2 ca Cu sub 2 O sub 7-x type (1212) structure, crystallized with space group P4/mmm and one formula in the unit cell. At 300 K, cell parameters a=3.8892(2) A, c=12.3099(6) A, the structure was refined with 25 parameters to R sub WP = 6.30%, R sub P = 4.38% for 3551 step intensities and R sub b = 5.01%, R sub f = 4.20% for 156 reflections. The goodness of fitting S=3.18. At 100K, cell parameters a=3.8866(4) A, c= 12.289(1) A, the structure was refined with 26 parameters to R sub WP = 8.42%, R sub P = 6.21% for 2676 step intensities and R sub b = 6.72%, R sub f = 5.28% for 120 reflections. The goodness of fitting S=2.32. Reasonable anisotropic thermal parameters were obtained. The compositions of Ba and Sr atoms were refined to about Ba sub 1.1 Sr sub 0.9 compared with the stoichiometric Ba sub 1.0 Sr sub 1.0

An approach to WWER fuels with BaCo

International Nuclear Information System (INIS)

Marino, A.; Demarco, G.

2008-01-01

BaCo is a code for the simulation of the behaviour of a nuclear fuel rod under operation conditions. BaCo, a quasi 2D code based on a finite differences scheme, has been used for simulating PHWR, CANDU, PWR, BWR, MOX, WWER, and experimental fuel rods. We improve the performance of BaCo with a set of tools based on the method of finite elements for 3D analysis of the stress-strain state. We can simulate any UO 2 pellet geometry. Standard WWER-440 fuel assemblies irradiated in the Kola-3 reactor of the CRP FUMEX II of the IAEA were the first WWER simulations with BaCo. We find a very good agreement among our calculations, the experimental results and other qualified fuel codes. We present the BaCo code and our results for PWR and WWER fuels of the CRP FUMEX II, the 3D analysis of WWER fuel pellet and the projections of these results with the Argentinean nuclear fuels development. (authors)

High speed atom source

International Nuclear Information System (INIS)

Hoshino, Hitoshi.

1990-01-01

In a high speed atom source, since the speed is not identical between ions and electrons, no sufficient neutralizing effect for ionic rays due to the mixing of the ionic rays and the electron rays can be obtained failing to obtain high speed atomic rays at high density. In view of the above, a speed control means is disposed for equalizing the speed of ions forming ionic rays and the speed of electrons forming electron rays. Further, incident angle of the electron rays and/or ionic rays to a magnet or an electrode is made variable. As a result, the relative speed between the ions and the electrons to the processing direction is reduced to zero, in which the probability of association between the ions and the electrons due to the coulomb force is increased to improve the neutralizing efficiency to easily obtain fine and high density high speed electron rays. Further, by varying the incident angle, a track capable of obtaining an ideal mixing depending on the energy of the neutralized ionic rays is formed. Since the high speed electron rays has such high density, they can be irradiated easily to the minute region of the specimen. (N.H.)

Size-dependent disproportionation (in 2-20 nm regime) and hybrid Bond Valence derived interatomic potentials for BaTaO2N

Science.gov (United States)

Anbalagan, Kousika; Thomas, Tiju

2018-05-01

Interatomic potentials for complex materials (like ceramic systems) are important for realistic molecular dynamics (MD) simulations. Such simulations are relevant for understanding equilibrium, transport and dynamical properties of materials, especially in the nanoregime. Here we derive a hybrid interatomic potential (based on bond valence (BV) derived Morse and Coulomb terms), for modeling a complex ceramic, barium tantalum oxynitride (BaTaO2N). This material has been chosen due to its relevance for capacitive and photoactive applications. However, the material presents processing challenges such as the emergence of non-stoichiometric phases during processing, demonstrating complex processing-property correlations. This makes MD investigations of this material both scientifically and technologically relevant. The BV based hybrid potential presented here has been used for simulating sintering of BaTaO2N nanoparticles ( 2-20 nm) under different conditions (using the relevant canonical ensemble). Notably, we show that sintering of particles of diameter 10 nm in size results in the formation of a cluster of tantalum and oxygen atoms at the interface of the BaTaO2N particles. This is in agreement with the experimental reports. The results presented here suggest that the potential proposed can be used to explore dynamical properties of BaTaO2N and related systems. This work will also open avenues for development of nanoscience-enabled aid-free sintering approaches to this and related materials.

Atomic size effect on the formation of ionized cluster beam epitaxy in Lennard-Jones systems

International Nuclear Information System (INIS)

Hsieh Horngming; Averback, R.S.

1991-01-01

Ionized cluster beam deposition is studied by molecular dynamics simulations in which the atomic size of incident cluster atoms is different from the size of substrate atoms. Lennard-Jones interatomic potentials are used for the two-component system. The results provide the morphologies of the overlayers for various atomic sizes and are compared to simulation results of molecular beam epitaxy. (orig.)

Intermetallic and metal-rich phases in the system Li-Ba-In-N

International Nuclear Information System (INIS)

Smetana, Volodymyr; Vajenine, Grigori V.; Kienle, Lorenz; Duppel, Viola; Simon, Arndt

2010-01-01

Three new intermetallic phases, BaLi 2.1 In 1.9 , BaLi 1.12 In 0.98 , and BaLi 1.06 In 1.16 and two subnitrides Li 35 In 45 Ba 39 N 9 and LiIn 2 Ba 3 N 0.83 have been synthesized and their crystal structures have been determined. According to single crystal X-ray diffraction data BaLi 2.1 In 1.9 and BaLi 1.12 In 0.98 crystallize with hexagonal symmetry (BaLi 2.1 In 1.9 : P6 3 /mmc, a=10.410(2), c=8.364(2) A, Z=6, V=785.0(2) A 3 ) and BaLi 1.12 In 0.98 : P6/mmm, a=17.469(1), c=10.6409(7) A, Z=30, V=2813.5(8) A 3 ), while BaLi 1.06 In 1.16 has a rhombohedral structure (R-3c, a=18.894(3), c=85.289(17) A, Z=276, V=26368(8) A 3 ). BaLi 2.1 In 1.9 is isostructural with the known phase BaLi 4 . The phase BaLi 1.12 In 0.98 is structurally related to Na 8 K 23 Cd 12 In 48 , while BaLi 1.06 In 1.16 is isostructural with Li 33.3 Ba 13.1 Ca 3 . A sample containing structurally similar BaLi 1.12 In 0.98 and BaLi 1.02 In 1.16 was also investigated by transmission electron microscopy. Li 35 In 45 Ba 39 N 9 and LiIn 2 Ba 3 N 0.83 crystallize with tetragonal (I-42m, a=15.299(2), c=30.682(6) A, Z=2, V=7182(2) A 3 ) and cubic (Fd-3m, a=14.913(2) A, Z=8, V=3316.7(7) A 3 ) symmetry, respectively. While the first-mentioned subnitride belongs to the Li 80 Ba 39 N 9 structure type, the second extends the structural family of Ba 6 In 4.78 N 2.72 . The structural features of the new compounds are discussed in comparison to the known phases and the results of total energy calculations. - Graphical abstract: One-dimensional chain of face-sharing centered icosahedra in BaLi 2.1 In 1.9

Incidence of leukemia among atomic bomb survivors in relation to neutron and gamma dose, Hiroshima and Nagasaki, 1950-71

International Nuclear Information System (INIS)

Ishimaru, Toranosuke; Otake, Masanori; Ichimaru, Michito.

1978-03-01

The incidence of leukemia during 1950-71 in the fixed mortality sample of atomic bomb survivors in Hiroshima and Nagasaki has been analyzed as a function of individual gamma and neutron kerma and marrow dose. Two dose response models were tested for each of acute leukemia, chronic granulocytic leukemia, and all types of leukemia, respectively. Each model postulates that leukemia incidence depends upon the sum of the separate risks imposed by the gamma ray and neutron doses; in Model I both are assumed to be directly proportional to the respective doses, while Model II assumes that while the risk from neutrons is directly proportional to the dose, the risk from gamma rays is proportional to dose-squared. Weighted regression analyses were performed for each model. When the two models were fitted to the data for all types of leukemia, the estimated regression coefficients corresponding to the neutron and gamma ray doses both differed significantly from zero, for each model. However, when analysis was restricted to acute leukemia, both the neutron and gamma ray coefficients were significant only for Model II, and with respect to chronic granulocytic leukemia, only the coefficient of the neutron dose was significant, using either Model I or Model II. It appeared that the responses of the two leukemia types differed by type of radiation. If the chronic granulocytic and acute leukemias are considered together, the Model II appears to fit the data slightly better than Model I, but neither models is rejected by the data. (author)

Wet routes of high purity BaTiO3 nanopowders

International Nuclear Information System (INIS)

Wang Liqiu; Liu Liang; Xue Dongfeng; Kang Hongmin; Liu Changhou

2007-01-01

High purity BaTiO 3 nanopowders were prepared in wet routes through stearic acid gel (SAG) and acetic acid gel (AAG) techniques, respectively. BaTiO 3 samples were characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectrometry, X-ray fluorescence spectrometry, and thermal gravimetric analysis. The present results indicate that both methods have a similar reaction process during calcination, while BaTiO 3 crystallites were initially formed at 550 deg. C by SAG and 800 deg. C by AAG. Both methods could produce BaTiO 3 powders with a cubic perovskite structure, while they had different grain size distributions within 25-50 nm for SAG and 50-80 nm for AAG. BaTiO 3 samples prepared by SAG had a lower agglomeration than those by AAG. SAG has shown many distinctive advantages in the preparation of high purity BaTiO 3 nanopowders, without Ba and Ti losses and hazardous wastes

Ferroelectric relaxor Ba(TiCe)O3

International Nuclear Information System (INIS)

Chen Ang; Zhi Jing; Yu Zhi

2002-01-01

The dielectric behaviour of Ba(Ti 1-y Ce y )O 3 solid solutions (y=0-0.3) has been studied. A small amount of Ce doping (y=0.02) has weak influence on the dielectric behaviour of Ba(Ti 1-y Ce y )O 3 . With increasing Ce concentration, three phase transitions of pure BaTiO 3 are pinched into one rounded dielectric peak with frequency dispersion, and the relaxation time follows the Vogel-Fulcher relation. The evolution from a normal ferroelectric to a ferroelectric relaxor is emphasized. High strains (S=∼0.1-0.19%) with a small hysteresis under ac fields are obtained in ferroelectric relaxors Ba(Ti 1-y Ce y )O 3 . The physical mechanism of the relaxation process, the pinching effect of the phase transitions and their influence on the ferroelectric and electrostrictive behaviour are discussed. (author)

Review and prospects of Atomic Energy Law

International Nuclear Information System (INIS)

Hartkopf, G.

1983-01-01

At the 7th German Symposium on Atomic Energy Law which took place on March 16th, 1983 in Goettingen the Undersecretary of State of the Federal Ministery of the Interior, Dr. Guenter Hartkopf, delivered the opening speech. The speech deals with the conditions set by constitutional law and ethics, improvement of nuclear liability, guide line for incident response, participation of the public in licensing procedures under atomic energy law, necessary measures to prevent damage, the concept of waste management. Also in future the safety of the citizens has absolute priority. (orig./HSCH) [de

Red, Green, and Blue Photoluminescence of Ba2SiO4:M (M = Eu3+, Eu2+, Sr2+ Nanophosphors

Directory of Open Access Journals (Sweden)

Claudia Wickleder

2013-07-01

Full Text Available Divalent europium doped barium orthosilicate is a very important phosphor for the production of light emitting diodes (LEDs, generally associated to the green emission color of micron-sized crystals synthesized by means of solid-state reactions. This work presents the combustion synthesis as an energy and time-saving preparation method for very small nano-sized Ba2SiO4 particles, flexibly doped to acquire different emission energies. The size of the resulting spherical nanoparticles (NPs of the green emitting Ba2SiO4:Eu2+ was estimated to about 35 nm applying the Scherrer equation and further characterized with aid of atomic force microscopy (AFM as well as scanning electron microscopy (SEM. This phosphor is able to build homogeneous luminescent suspensions and was successfully down-sized without changing the optical properties in comparison to the bulk phosphors. Besides the X-ray diffraction (XRD analysis and the different types of microscopy, the samples were characterized by luminescence spectroscopy. Undoped Ba2SiO4 NPs are not luminescent, but show characteristic red emission of the 5D0 → 7FJ (J = 0–4 electronic transitions when doped with Eu3+ ions. Moreover, these orthosilicate nanoparticles generate blue light at low temperatures due to impurity-trapped excitons, introduced by the partial substitution of the Ba2+ with Sr2+ ions in the Ba2SiO4 lattice causing a substantial distortion. A model for the temperature behavior of the defect luminescence as well as for their nature is provided, based on temperature-dependent luminescence spectra and lifetime measurements.

Grazing incidence polarized neutron scattering in reflection ...

Indian Academy of Sciences (India)

journal of. January 2012 physics pp. 1–58. Grazing incidence polarized ..... atomic distances, the neutron has an energy which is low compared to molecular binding ...... cores and that of the Co ions in the AF oxide coatings. ...... [32] C Leighton, M R Fitzsimmons, P Yashar, A Hoffmann, J Nogus, J Dura, C F Majkrzak and.

Outcome and status of microsatellite stability in Japanese atomic bomb survivors with early gastric carcinoma.

Science.gov (United States)

Yamamoto, Manabu; Taguchi, Kenichi; Yamanaka, Takeharu; Matsuyama, Ayumi; Yoshinaga, Keiji; Tsutsui, Shinichi; Ishida, Teruyoshi

2013-03-01

In the decade after the 1945 atomic bombing of Hiroshima, a high incidence of leukemia was observed among atomic bomb survivors. However, the incidence of other cancers gradually increased, while that of leukemia decreased after this period. We evaluated the clinical outcome of early gastric cancer and microsatellite stability over a long-term period in atomic bomb survivors. The results of surgical treatment for early gastric cancer were reviewed for 117 atomic bomb survivors and 394 control patients between 1995 and 2006. In addition, immunohistochemical staining for hMSH2 and hMLH1 expression was performed to evaluate the status of microsatellite stability in 57 atomic bomb survivors and 82 control patients. The long-term survival rate for early gastric cancer in atomic bomb survivors was significantly lower than that in control patients (p bomb survivorship was related to defective hMSH2 and/or hMLH1 expression. The prognosis of early gastric cancer in atomic bomb survivors was poor and was related to age and sex, rather than to being an atomic bomb survivor. Furthermore, a higher rate of defective hMSH2 and/or hMLH1 expression was observed in the survivors.

Metaplasia mieloide do baço na Ancilostomose

Directory of Open Access Journals (Sweden)

W. O. Cruz

1934-06-01

Full Text Available Pesquizamos, no figado e baço de dez casos puros de ancilostomose, elementos hemocitopoieticos; verificamos o peso do baço em 23 casos de individuos com idades compreendidas entre 3 e 60 anos; não encontramos, em nenhum caso, celulas hemoformadoras no figado. Em sete casos, encontramos, no baço, elementos da série vermelha em adiantado estado de evolução (eritroblastos ortocromaticos de nucleo picnotico. Em alguns destes casos observamos megacariocitos e numerosos mielocitos eosinofilos. Os tres casos que não apresentavam metaplasia mieloide no baço, eram os de individuos acima de 50 anos de idade. Entretanto, em outro caso de um individuo com 59 anos esta metaplasia foi verificada. Em individuos acima de 20 anos, o peso médio do baço, em nove casos, mostrou-se igual ao peso normal. Em 14 casos, compreendidos entre 3 e 14 anos, o peso deste orgão foi sempre sensivelmente mais elevado que nos normais de idade correspondente. Estes resultados sugerem a possibilidade de ser a metaplasia mieloide responsavel pelos aumentos de pezo nos baços de individuos jovens, vitimados pela anemia ancilostomica. A notavel proliferação dos eritroblastos ortocromaticos mostra que o grão e a rapidez da regeneração sanguinea, após a administração de ferro, são devidos, essencialmente, á grande quantidade de hemoglobina já preformada no baço e na medula ossea dos organismos ancilostomados.

Angular momentum effects in electron scattering from atoms

International Nuclear Information System (INIS)

Williams, J F; Cvejanovie, D; Samarin, S; Pravica, L; Napier, S; Sergeant, A

2007-01-01

This paper concerns angular momentum-dependent phenomena in excited gas-phase atoms using incident photons or electrons in scattering experiments. A brief overview indicates the main capabilities of experimental techniques and the information which can be deduced about atomic structure and dynamics from conservation of momenta with measurement of polarization and detection of the number of emerging electrons, photons and ions. Maximum information may be obtained when the incident particles and the targets are state-selected both before and after scattering. The fundamental scattering amplitudes and their relative phases, and consequently derived quantities such as the parameters describing the electron charge cloud of the atomic target, have enabled significant advances of understanding of collision mechanisms. The angular momentum-dependent scattering probabilities change when, for example, the spin-orbit interaction for the target electrons becomes large compared with the Coulomb electron-electron interactions and also when electron exchange and the relative orientation of the electron spins change. Several examples are discussed to indicate significant principles and recent advances. Major contributions to this field from the technology associated with electron spin production and detection time, as well as time-coincidence detection, are discussed. New results from the authors' laboratory are presented

Shadow-free multimers as extreme-performance meta-atoms

Science.gov (United States)

Safari, M.; Albooyeh, M.; Simovski, C. R.; Tretyakov, S. A.

2018-02-01

We generalize the concept of parity-time symmetric structures with the goal to create meta-atoms exhibiting extraordinary abilities to overcome the presumed limitations in the scattering of overall lossless particles, such as nonzero forward scattering and the equality of scattering and extinction powers for all lossless particles. Although the forward scattering amplitude and the extinction cross section of our proposed meta-atoms vanish, they scatter incident energy into other directions, with controllable directionality. These meta-atoms possess extreme electromagnetic properties not achievable for passive scatterers. As an example, we study meta-atoms consisting of two or three small dipole scatterers. We consider possible microwave realizations in the form of short dipole antennas loaded by lumped elements. The proposed meta-atom empowers extraordinary response of a shadow-free scatterer and theoretically enables most unusual material properties when used as a building block of an artificial medium.

Compounds of the type Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ with Bsup(II) = Mg, Ca, Sr, Ba, and Msup(V) = Nb, Ta

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Thumm, I; Herrmann, M [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1981-08-01

The hexagonal perovskites Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ (Msup(V) = Nb, Ta) crystallize with Bsup(II) = Mg, Ca in a 3 L structure (sequence (c)/sub 3/) and Bsup(II) = Sr in the hexagonal BaTiO/sub 3/ type (6 L; sequence (hcc)/sub 2/) with an 1:2 order for the B and M ions. Intensity calculations for Ba/sub 3/SrNb/sub 2/O/sub 9/ and Ba/sub 3/SrTa/sub 2/O/sub 9/ gave in the space group P6/sub 3//mmc a refined, intensity related R' value of 8.4% (Nb) and 9.0% (Ta) respectively. For Bsup(II) = Ba the perovskite Ba/sub 3/BaTa/sub 2/O/sub 9/ has an orthorhombic distorted 6 L structure and forms with Ba/sub 3/SrTa/sub 2/O/sub 9/ a continuous series of mixed crystals (Ba/sub 3/Srsub(1-x)Basub(x)Ta/sub 2/O/sub 9/). In the system Ba/sub 3/Srsub(1-x)Basub(x)Nb/sub 2/O/sub 9/ the range of existence of the hexagonal BaTiO/sub 3/ type is confined to the Sr richer end. The pure Ba compound posesses a proper structure type (5 L: Ba/sub 5/BaNb/sub 3/vacantOsub(13.5)vacantsub(1.5)).

Spectroscopic and thermal degradation behavior of Mg(II), Ca(II), Ba(II) and Sr(II) complexes with paracetamol drug

OpenAIRE

Moamen S. Refat; Gehad G. Mohamed; Mohamed Y. El-Sayed; Hamada M.A. Killa; Hammad Fetooh

2017-01-01

Complexes of Mg(II), Ca(II), Ba(II) and Sr(II) with paracetamol drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR, and 1H NMR spectroscopy and thermal analysis, as well as screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as paracetamol behaves as a neutral bidentate ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the amide group. From the microanalytical dat...

Barium contributions to the valence electronic structure of YBa2Cu3O7-δ, PrBa2Cu3O7-δ, and other barium-containing compounds

International Nuclear Information System (INIS)

Mueller, D.R.; Wallace, J.S.; Jia, J.J.; O'Brien, W.L.; Dong, Q.; Callcott, T.A.; Miyano, K.E.; Ederer, D.L.

1995-01-01

Monochromatic photon beams were used to excite barium N IV,V soft x-ray emission spectra from YBa 2 Cu 3 O 7-δ , PrBa 2 Cu 3 O 7-δ , BaF 2 , and BaTiO 3 . Near threshold excitation was used to demonstrate that small contributions to the barium N V and N IV emission spectra in the energy region above the 5p→4d core-core transitions do not arise as satellite emission from transitions in multiply excited atoms but rather occur as a result of transitions from the valence states. The emission spectrum of YBa 2 Cu 3 O 7-δ and PrBa 2 Cu 3 O 7-δ reveals a contribution to the electronic density of states at the barium site in the region near the Fermi level. The YBa 2 Cu 3 O 7-δ compound is a superconductor and PrBa 2 Cu 3 O 7-δ is an insulator. It has been proposed that the difference between them is due to mixing of praseodymium and barium among the sites occupied by yttrium and barium, with an accompanying change in electronic structure. However, our measurements indicate that the barium partial density of states for the two compounds are essentially identical

First-principles study of (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions

Science.gov (United States)

Amoroso, Danila; Cano, Andrés; Ghosez, Philippe

2018-05-01

(Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions are the building blocks of lead-free piezoelectric materials that attract a renewed interest. We investigate the properties of these systems by means of first-principles calculations, with a focus on the lattice dynamics and the competition between different ferroelectric phases. We first analyze the four parent compounds in order to compare their properties and their different tendency towards ferroelectricity. The core of our study is systematic characterization of the binary systems (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 within both the virtual crystal approximation and direct supercell calculations. In the case of Ca doping, we find a gradual transformation from B -site to A -site ferroelectricity due to steric effects that largely determines the behavior of the system. In the case of Zr doping, in contrast, the behavior is eventually dominated by cooperative Zr-Ti motions and the local electrostatics. In addition, our comparative study reveals that the specific microscopic physics of these solids sets severe limits to the applicability of the virtual crystal approximation for these systems.

In-plane anisotropy of the electric field gradient in Ba(Fe 1 -xCox)2As2 observed by 75As NMR

Science.gov (United States)

Toyoda, Masayuki; Ichikawa, Akihiro; Kobayashi, Yoshiaki; Sato, Masatoshi; Itoh, Masayuki

2018-05-01

We have performed 75As NMR measurements on single crystals to investigate the nematic behavior via the in-plane anisotropy of the electronic state at the As site far from Co impurities in the representative iron arsenides Ba (Fe1-xCox) 2As2 . From the analysis of the angular dependence of the NMR satellites in the c plane using the binominal distribution, we find that there is the in-plane fourfold symmetry breaking, namely, the orthorhombic-type anisotropy in the electric field gradient (EFG) at the As site with no Co atom at the nearest neighboring Fe sites even in the tetragonal phase of both BaFe2As2 and Ba (Fe1-xCox) 2As2(x ≠0 ) . The NMR spectrum in the antiferromagnetically ordered state of BaFe2As2 is shown not to support a nanotwin model on the basis of the nematic order proposed from the pair-distribution analysis of neutron scattering data. Based on results of the x and temperature T dependences of the in-plane anisotropy in the wide x and T ranges, the symmetry breaking is concluded to come from the local orthorhombic domains induced by disorder such as Co impurities or lattice imperfections. Furthermore, we find that the asymmetry parameter of EFG η obeys the Curie-Weiss law which may be governed by nematic susceptibility, and the Weiss temperature becomes zero at xc˜0.05 in Ba (Fe1-xCox) 2As2 .

Effect of Barium-Precursors on Reaction Kinetics in Y-Ba-Cu-O System

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The reactions of stoichiometric Y2O3, CuO, and different Ba salts or oxides (BaCO3, Ba(NO3)2, BaO2, BaCuO2) for forming various compounds in the Y-Ba-Cu-O system (i.e., YBa2Cu3O7-δ, BaCuO2, Y2BaCuO5 and Y2Cu2O5) were systematically investigated by thermal analysis and X-ray diffractometry. The relevant activation energies were calculated from thermogravimetric data. It is found that the reaction pathway significantly depends on the thermal stability of the Ba precursors. Binary BaO-CuO phases form at low temperature (650～700 ℃) when in presence of easy-to-decompose Ba precursors, and then slowly transform to ternary compounds. On the contrary, when Ba ions are released at temperature higher than 900 ℃, ternary phases form directly from the components.

Structural and superconducting properties of oxygen-deficient NdBa sub 2 Cu sub 3 O sub 7 minus. delta

Energy Technology Data Exchange (ETDEWEB)

Shaked, H. (Nuclear Research Center-Negev, Post Office Box 9001, Beer Sheva, Israel (IL) Ben Gurion University of the Negev, Post Office Box 653, Beer Sheva, Israel (IL)); Veal, B.W.; Faber, J. Jr.; Hitterman, R.L.; Balachandran, U.; Tomlins, G.; Shi, H.; Morss, L.; Paulikas, A.P. (Argonne National Laboratory, Argonne, Illinois 60439 (USA))

1990-03-01

Neutron diffraction was used to determine the structural properties of oxygen deficient NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} for 0.09{lt}{delta}{lt}0.74. It was found that superconductivity disappears at the orthorhombic-to-tetragonal phase transition which occurs at {delta}{sub {ital O}{ital T}}=0.45. Structural parameters vary smoothly with {delta} but exhibit a change in slope at the orthorhombic-to-tetragonal transition. The structural properties exhibit the same features found in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} where {delta}{sub {ital O}{ital T}}=0.65. It is shown that the repulsion energy of oxygen atoms in the O(1) and O(5) sites in NdBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} is smaller than in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. This lower repulsion energy stabilizes the orthorhombic phase at lower values of {delta}. It is argued that the disappearance of superconductivity at the orthorhombic-to-tetragonal transition is an inherent property of the {ital R}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} ({ital R} denotes rare earth) system.

Atlas cross section for scattering of muonic hydrogen atoms on hydrogen isotope molecules

International Nuclear Information System (INIS)

Adamczak, A.; Faifman, M.P.; Ponomarev, L.I.

1996-01-01

The total cross sections of the elastic, spin-flip, and charge-exchange processes for the scattering of muonic hydrogen isotope atoms (pμ, dμ, tμ) in the ground state on the hydrogen isotope molecules (H 2 , D 2 , T 2 , HD, HT, DT) are calculated. The scattering cross sections of muonic hydrogen isotope atoms on hydrogen isotope nuclei obtained earlier in the multichannel adiabatic approach are used in the calculations. Molecular effects (electron screening, rotational and vibrational excitations of target molecules, etc.) are taken into account. The spin effects of the target molecules and of the incident muonic atoms are included. the cross sections are averaged over the Boltzmann distribution of the molecule rotational states and the Maxwellian distribution of the target molecule kinetic energies for temperatures 30, 100, 300, and 1000 K. The cross sections are given for kinetic energies of the incident muonic atoms ranging from 0.001 to 100 eV in the laboratory frame. 45 refs., 6 tabs

Strain induced optical properties of BaReO3

Science.gov (United States)

Kumavat, Sandip R.; Kansara, Shivam; Gupta, Sanjeev K.; Sonvane, Yogesh

2018-05-01

Here, we have performed strain induce optical properties of BaReO3 by using density functional theory (DFT). We noticed that after applying intrinsic and extrinsic strain to the BaReO3, it shows the metallic behavior. We also studied optical properties, which show good activity in the ultraviolet region. The results show that after applying intrinsic and extrinsic strain to BaReO3 the absorption peaks are shifted towards the high UV region of the spectrum. Thus, we concluded that, BaReO3 material with extrinsic strain can be useful for high frequency UV device and optoelectronic devices.

Excited-atom production by electron and ion bombardment of alkali halides

International Nuclear Information System (INIS)

Walkup, R.E.; Avouris, P.; Ghosh, A.P.

1987-01-01

We present experimental results on the production of excited atoms by electron and ion bombardment of alkali halides. For the case of electron bombardment, Doppler shift measurements show that the electronically excited atoms have a thermal velocity distribution in equilibrium with the surface temperature. Measurements of the absolute yield of excited atoms, the distribution of population among the excited states, and the systematic dependence on incident electron current and sample temperature support a model in which the excited atoms are produced by gas-phase collisions between desorbed ground-state atoms and secondary electrons. In contrast, for the case of ion bombardment, the excited atoms are directly sputtered from the surface, with velocity distributions characteristic of a collision cascade, and with typical energies of --10 eV

IR-spectroscopic study and electrical properties of glasses in the Ba(PO3)2-Ba(Hal)2 systems

International Nuclear Information System (INIS)

Sokolov, I.A.; Tarlakov, Yu.P.; Murin, I.V.; Pronkin, A.A.

2000-01-01

Temperature-concentration dependence of electric conductivity of glasses in the systems Ba(PO 3 ) 2 -Ba(Hal) 2 , where Hal = Cl, Br, I, is studied by the method of conductometry, the numbers of iodide-ions transfer are determined and their concentration dependence is found. Data of IR spectroscopy permitted ascertained participation of halide ions in formation of anionic constituent of the glass structure at the expense of bridge bonds formation, as well as formation of structural-chemical units of [(Hal) - Ba 2+ O - POO 2/2 ] type, their dissociation giving rise to formation of halide ions their dissociation giving rise to formation of halide ions taking part in electric current transfer [ru

High-Temperature Superconductivity in Doped BaFe2As2

International Nuclear Information System (INIS)

Martin, Marianne

2011-01-01

This thesis provides a detailed look on the synthesis, structural features and physical properties of iron arsenides. Especially the properties of BaFe 2 As 2 and the solid solutions (Ba 1-x K x )Fe 2 As 2 , (Ba 1-x Sr x )Fe 2 As 2 and BaFe 2 (As 1-x P x ) 2 which were all synthesized by solid state reactions by heating mixtures of the elements, were intensively investigated.

Use of synchrotron and laser radiations for present and future photoionization studies in excited atoms and ions

International Nuclear Information System (INIS)

Wuilleumier, F.J.

1984-01-01

The status of experiments in photoionization of atoms in excited states is reviewed, with emphasis given to synchrotron and laser photon sources. A technique for exciting the photoionization spectrum of Na atoms using the flux emitted from the bending magnetic of a storage ring is discussed in detail. Some problems in interpreting photoionization spectrum of Ba in the excited state, due to the presence of higher orders are considered. A design approach for a positron storage ring to produce coherent radiation in the VUV is described. It is shown that combined use of a CW dye laser and the positron storage ring will allow new progress to be made in photoionization studies of excited atoms. Some of the experiments to be carried out using the positron storage ring include: measurements of collisional ionization in rare earth metal atoms of low atomic density; photoionization measurements at lower laser powers, leading to an extension of the CW tunability range; and photoionization studies of multiply charged positive ions. 21 references

Molecular recognition at methyl methacrylate/n-butyl acrylate (MMA/nBA) monomer unit boundaries of phospholipids at p-MMA/nBA copolymer surfaces.

Science.gov (United States)

Yu, Min; Urban, Marek W; Sheng, Yinghong; Leszczynski, Jerzy

2008-09-16

Lipid structural features and their interactions with proteins provide a useful vehicle for further advances in membrane proteins research. To mimic one of potential lipid-protein interactions we synthesized poly(methyl methacrylate/ n-butyl acrylate) (p-MMA/nBA) colloidal particles that were stabilized by phospholipid (PLs). Upon the particle coalescence, PL stratification resulted in the formation of surface localized ionic clusters (SLICs). These entities are capable of recognizing MMA/nBA monomer interfaces along the p-MMA/nBA copolymer backbone and form crystalline SLICs at the monomer interface. By utilizing attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and selected area electron diffraction (SAD) combined with ab initio calculations, studies were conducted that identified the origin of SLICs as well as their structural features formed on the surface of p-MMA/nBA copolymer films stabilized by 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) PL. Specific entities responsible for SLIC formation are selective noncovalent bonds of anionic phosphate and cationic quaternary ammonium segments of DLPC that interact with two neighboring carbonyl groups of nBA and MMA monomers of the p-MMA/nBA polymer backbone. To the best of our knowledge this is the first example of molecular recognition facilitated by coalescence of copolymer colloidal particles and the ability of PLs to form SLICs at the boundaries of the neighboring MMA and nBA monomer units of the p-MMA/nBA chain. The dominating noncovalent bonds responsible for the molecular recognition is a combination of H-bonding and electrostatic interactions.

Epitaxial thin-film growth of Ruddlesden-Popper-type Ba3Zr2O7 from a BaZrO3 target by pulsed laser deposition

International Nuclear Information System (INIS)

Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina; Awan, M.S.; Bashir, Shazia; Iqbal, Nida

2016-01-01

Ruddlesden-Popper Ba 3 Zr 2 O 7 thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba 3 Zr 2 O 7 phase from BaZrO 3 target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba 3 Zr 2 O 7 thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba 3 Zr 2 O 7 phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba 3 Zr 2 O 7 Ruddlesden-Popper-type perovskite structure. (orig.)

Mesocrystals luminescent BaZrHfO{sub 3} synthesized via hydrothermal process assisted by microwave

Energy Technology Data Exchange (ETDEWEB)

Fassbender, Rafael Uarth, E-mail: uarth.fisica@gmail.com

2016-07-01

Full text: The Barium Zirconate (BaZrO{sub 3}), is a ceramic oxide belonging to the functional group of perovskites (ABO{sub 3}), this compound can be doped with hafniun (Hf) in solid solution by microwave assisted hydrothermal method (MAH) radioluminescent increases their properties. This method allows to obtain barium zirconate at low temperature as 140 deg C and short times as 160 minutes. The choice of Hafnium (Hf) as a dopant is based on its similarity with Zirconium (Zr), another good reason for this choice is that the Hafnium has intrinsic luminescent characteristics. In general, radioluminescent materials have high density and high atomic mass (atomic number of Hafnium is 72), thereby facilitating the absorption of ionizing radiation to convert it into visible light, this characteristic is strongly dependent on the morphology and especially the electronic structure of (BaZrO{sub 3}). This work consisted in production of barium zirconate powders doped 1-2-4-8-16% (Hf) using (MAH) method. For the characterization of the powders was employed methods : a) X-ray diffraction, b) Raman Spectroscopy, c) Xanes, d) photoluminescence spectroscopy. After the electronic and structural characterization the powders were introduced in a polymeric resin (nylon-BZO), one new characterizations will be performed to validate the results obtained in the production of films to the results already obtained for the powders. We conclude so far, that the powders-doped with 16% Hf has an intense luminescent emission compared to the powders with less concentration of Hf. The small structural change that causes the Hf in (BZO) is considered as a secondary factory. (author)

Study of e-+ alkaline atom inelastic collisions with the Glauber approxmation

International Nuclear Information System (INIS)

Bielschowsky, C.E.

1984-01-01

Glauber's approximation is used to study discrete excitations in alkali atoms by electron impact. The interaction between the incident electron and the core electrons and (N-1) nuclear charges is described through an Yukawa-like potential. Analitical expressions for m 2 S and m 2 P excitations are obtained, as well as numerical results for several excitations processes in alkali atoms. (Author) [pt

Kampelite, Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O, a new very complex Ba-Sc phosphate mineral from the Kovdor phoscorite-carbonatite complex (Kola Peninsula, Russia)

Science.gov (United States)

Yakovenchuk, Victor N.; Ivanyuk, Gregory Yu.; Pakhomovsky, Yakov A.; Panikorovskii, Taras L.; Britvin, Sergei N.; Krivovichev, Sergey V.; Shilovskikh, Vladimir V.; Bocharov, Vladimir N.

2018-02-01

Kampelite, Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O, is a new Ba-Sc phosphate from the Kovdor phoscorite-carbonatite complex (Kola Peninsula, Russia). It is orthorhombic, Pnma, a = 11.256(1), b = 8.512(1), c = 27.707(4) Å, V = 2654.6(3) Å3 and Z = 4 (from powder diffraction data) or a = 11.2261(9), b = 8.5039(6), c = 27.699(2) Å, V = 2644.3(3) Å3 (from single-crystal diffraction data). The mineral was found in a void within the calcite-magnetite phoscorite (enriched in hydroxylapatite and Sc-rich baddeleyite) inside the axial zone of the Kovdor phoscorite-carbonatite pipe. Kampelite forms radiated aggregates (up to 1.5 mm in diameter) of platy crystals grown on the surfaces of crystals of quintinite-2 H in close association with pyrite, bobierrite and quintinite-3 R. Kampelite is colourless, with a pearly lustre and a white streak. The cleavage is perfect on {001}, the fracture is smooth. Mohs hardness is about 1. In transmitted light, the mineral is colourless without pleochroism or dispersion. Kampelite is biaxial + (pseudouniaxial), α ≈ β = 1.607(2), γ = 1.612(2) (589 nm), and 2 V calc = 0°. The calculated and measured densities are 3.28 and 3.07(3) g·cm-3, respectively. The mean chemical composition determined by electron microprobe is: MgO 4.79, Al2O3 0.45, P2O5 31.66, K2O 0.34, Sc2O3 16.17, Mn2O3 1.62, Fe2O3 1.38, SrO 3.44, and BaO 29.81 wt%. The H2O content estimated from the crystal-structure refinement is 7.12 wt%, giving a total of 96.51 wt%. The empirical formula calculated on the basis of P = 6 apfu (atoms per formula unit) is (Ba2.62Sr0.45K0.10Ca0.06)Σ3.23Mg1.60Mn0.28(Sc3.15Fe3+ 0.23Al0.12)Σ3.50(PO4)6(OH)2.61·4.01H2O. The simplified formula is Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O. The mineral easily dissolves in 10% cold HCl. The strongest X-ray powder-diffraction lines [listed as d in Å ( I) ( hkl)] are as follows: 15.80(100)(001), 13.86(45)(002), 3.184(18)(223), 3.129(19)(026), 2.756(16)(402), 2.688(24)(10 10). The crystal structure of kampelite was

Subwavelength Localization of Atomic Excitation Using Electromagnetically Induced Transparency

Directory of Open Access Journals (Sweden)

J. A. Miles

2013-09-01

Full Text Available We report an experiment in which an atomic excitation is localized to a spatial width that is a factor of 8 smaller than the wavelength of the incident light. The experiment utilizes the sensitivity of the dark state of electromagnetically induced transparency (EIT to the intensity of the coupling laser beam. A standing-wave coupling laser with a sinusoidally varying intensity yields tightly confined Raman excitations during the EIT process. The excitations, located near the nodes of the intensity profile, have a width of 100 nm. The experiment is performed using ultracold ^{87}Rb atoms trapped in an optical dipole trap, and atomic localization is achieved with EIT pulses that are approximately 100 ns long. To probe subwavelength atom localization, we have developed a technique that can measure the width of the atomic excitations with nanometer spatial resolution.

Crystalline and lattice matched Ba0.7Si0.3O layers on plane and vicinal Si(001) surfaces

International Nuclear Information System (INIS)

Zachariae, J.

2006-01-01

In this work the low temperature growth conditions of epitaxial and lattice-matched Ba 0.7 Sr 0.3 O layers on Si(100) were investigated using the combination of low energy electron diffraction (LEED), x-ray photoemission (XPS) and electron energy loss spectroscopy (EELS). With these methods crystallinity, stoichiometry and electronic structure of both occupied and unoccupied levels were studied as a function of layer thickness. Oxide layers were generated by evaporating the metals in oxygen ambient pressure with the sample at room temperature. Perfect crystallinity and lattice matching was only obtained starting with a preadsorbed monolayer (ML) of Sr or Ba at a concentration close to one monolayer. The XPS analysis shows that Ba 0.7 Sr 0.3 O as a high-K gate dielectric offers an adequate band gap, an appropriate band alignment and a atomically sharp interface to the Si(001) substrate. No silicide and silicate species, or SiO 2 formation at the interface after oxidation were found. To show that Ba 0.7 Sr 0.3 O is really appropriate to replace SiO 2 as a gate dielectric, first C-V and I-V curves of MOS-diodes with SrO, BaO and Ba 0.7 Sr 0.3 O as gateoxide were measured under ambient conditions. Besides other results, it turns out that the measured dielectric constant of Ba 0.7 Sr 0.3 O conforms with the expected value of ε ∼ 25 - 30. Exploring ways for self-organized structuring of insulating films, the possibility to produce replicas of step trains, given by a vicinal Si(001)-4 [110] surface, in layers of crystalline and perfectly lattice matched Ba 0.7 Sr 0.3 O were investigated. For this purpose high-resolution spot profile analyses in low-energy electron diffraction (SPA-LEED) both on flat Si(001) and on vicinal Si(001)-4 [110] were carried out. The G(S) analysis of these mixed oxide layers reveals a strong influence of local compositional fluctuations of Sr and Ba ions and their respective scattering phases, which appears as an unphysically large variation

Experimental study on Ra2+ uptake by barite (BaSO{sub 4}). Kinetics of solid solution formation via BaSO{sub 4} dissolution and Ra{sub x}Ba{sub 1-x}SO{sub 4} (re) precipitation

Energy Technology Data Exchange (ETDEWEB)

Bosbach, Dirk; Boettle, Melanie; Metz, Volker (Karlsruher Inst. fuer Technologie, Inst fuer Nukleare Entsorgung (INE), Karlsruhe (Germany))

2010-03-15

226Ra2+ and 133Ba2+ uptake by barite in aqueous solution is studied on the basis of batch type experiments with two different barite powders with different specific surface area (0.5 m2/g and 3.2 m2/g, respectively). The uptake of 226Ra2+ and 133Ba2+ is not only limited to adsorption reactions but proceeds significantly into the bulk of the barite crystals. 133Ba2+ uptake kinetics is affected by various parameters, such as amount of sample, specific surface area, sample type and solution composition. In the case of 133Ba2+, complete isotopic equilibration of the 133Ba2+ spiked solution with the barite powder occurs within 50 to 600 days. This information is derived by monitoring the aqueous 133Ba2+ concentration combined with simple mass balance calculations. In the case of 226Ra2+ a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution forms and the uptake rate drops significantly within 400 days. The observed 226Ra2+ concentration in solution is controlled by the solubility of a Ra{sub x}Ba{sub 1-x}SO{sub 4} solid solution and several orders of magnitude below the Ra2+ solubility with respect to a pure RaSO{sub 4}(s) end member. It cannot be demonstrated unambiguously that a zero exchange rate and therefore thermodynamic equilibrium has been established within the observation period. The observed concentrations may be interpreted either as (1) a partial equilibration of 20 to 50% of the barite crystals with 226Ra2+ or (2) as complete equilibration of a Ra{sub 0.000128}Ba{sub 0.999872}SO{sub 4} solid solution with 226Ra2+ with no pure barite left. In both cases it is concluded that equilibration between aqueous Ra2+ and barite involves the replacement of a substantial fraction of the initial barite and proceeds significantly beyond pure surface adsorption processes

Enhancement of polarization property of silane-modified BaTiO3 nanoparticles and its effect in increasing dielectric property of epoxy/BaTiO3 nanocomposites

Directory of Open Access Journals (Sweden)

Thi Tuyet Mai Phan

2016-03-01

Full Text Available The surface modification of synthesized nano-BaTiO3 particles was carried out using γ-aminopropyl trimethoxy silane (γ-APS in an ethanol/water solution. The modified particles were characterized by FTIR, TGA, surface charge analysis, and by dielectric constant measurement. The silane molecules were attached to the surface of BaTiO3 particles through SiOBaTiO3 bonds. The γ-APS grafted on BaTiO3 made the dielectric constant of the particles increase at frequencies ≥0.3 kHz in a wide range of temperature (25 °C–140 °C, due to the presence of NH2 groups. The dependence of the polarization vs. electrical field was measured in order to elucidate the dielectric behavior of the silane treated BaTiO3 in comparison to untreated BaTiO3. The nanocomposite based on epoxy resin containing BaTiO3 nanoparticles untreated and treated with γ-APS was also prepared and characterized. The results indicated that the γ-APS-modified BaTiO3 surfaces significantly enhanced the dielectric property of the nanocomposite.

Spectroscopy and laser test emission in Tm3+ : BaYLuF8 single crystal

Science.gov (United States)

Parisi, D.; Veronesi, S.; Volpi, A.; Gemmi, M.; Tonelli, M.; Cassanho, A.; Jenssen, H. P.

2014-01-01

A novel laser material BaYLuF8 (BYLF), doped with 12 at% of Tm3+, has been grown and optically investigated, in order to evaluate its potential performances as a 2 µm laser. The BYLF crystal is interesting mainly because indications are that the mixed crystal would be sturdier than BaY2F8 (BYF). The addition of lutetium would improve the thermo-mechanical properties of the host. Absorption, fluorescence and lifetime measurements have been performed in the temperature range 10-300 K focusing on the 3H4 and 3F4 manifolds, those involved in the laser scheme at 2 µm. The Stark sublevels structure of Tm3+ up to the 1D2 manifold has been figured out. Diode-pumped CW laser emission at 2 µm has been achieved obtaining a slope efficiency of about 28% with respect to the absorbed power, by pumping along the Z-axis. A maximum output power of 240 mW was achieved by pumping along the favourable Y-axis, with an incident power of about 800 mW.

Immunohistochemical analysis of colorectal cancer among atomic bomb survivors in Hiroshima

International Nuclear Information System (INIS)

Yamamoto, Masami; Yamamoto, Tetsuro; Hata, Jotaro; Nakagawa, Hitoshi; Nakatsuka, Hirofumi; Tahara, Eiichi.

1987-01-01

In order to elucidate the biological characteristics of colorectal cancer among atomic bomb survivors in Hiroshima, a total of 159 cases of colorectal cancers comprising 73 cases in exposed atomic bomb survivors and 86 cases in non-exposed individuals were examined histologically and immunohistochemically for various functioning proteins. No statistical differences could be demonstrated in the incidence of various marker expressions of colorectal cancers between the exposed group and control group. However, comparison by the site of colorectal cancer showed that sigmoid colon cancers in the exposed group or high dose group showed a significantly higher frequency of glycoproteins such as α 1 -antichymotrypsin (ACT), secretory component (SC), α 1 -antitrypsin (AAT), and human chorionic gonadotropin (HCG) when compared with the control group. These results correlated well with the epidemiological data that the radiation effect on the incidence of colorectal cancer in atomic bomb survivors was most remarkable in the sigmoid colon. (author)

Determination of the hydrogen positions in the novel barium boroarsenate Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] by combined single crystal X-ray and powder neutron investigations

Energy Technology Data Exchange (ETDEWEB)

Lieb, Alexandra [School of Chemistry, University of Southampton (United Kingdom); Fakultaet fuer Verfahrens- und Systemtechnik, Lehrstuhl fuer Technische Chemie, Otto-von-Guericke-Universitaet, Magdeburg (Germany); Weller, Mark T. [School of Chemistry, University of Southampton (United Kingdom); Department of Chemistry, University of Bath (United Kingdom)

2017-11-17

The boroarsenate Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was obtained by the reaction of NH{sub 4}H{sub 2}AsO{sub 4}, B(OH){sub 3} and BaBr{sub 2}.2H{sub 2}O in the melt. Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was obtained as thin colorless needles, together with spherical crystals of BAsO{sub 4} as by-product, grown on a pellet of Ba[BAsO{sub 5}]. The products could be separated mechanically. For neutron scattering experiments a sample was prepared with {sup 11}B(OH){sub 3} as a starting material. The crystal structure of Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was determined by single-crystal X-ray diffraction and exhibits a layer structure with an unprecedented layer topology. The exact positions of the hydrogen atoms were determined using combined single-crystal X-ray and powder neutron diffraction investigations. Ba[B{sub 2}As{sub 2}O{sub 8}(OH){sub 2}] was further characterized by IR spectroscopy and EDX analysis. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Controlled Confinement of Half-metallic 2D Electron Gas in BaTiO3/Ba2FeReO6/BaTiO3 Heterostructures: A First-principles Study

Science.gov (United States)

Saha-Dasgupta, Tanusri; Baidya, Santu; Waghmare, Umesh; Paramekanti, Arun

Using density functional theory calculations, we establish that the half-metallicity of bulk Ba2FeReO6 survives down i to 1 nm thickness in BaTiO3/Ba2FeReO6/BaTiO3 heterostructures grown along the (001) and (111) directions. The confinement of the two-dimensional (2D) electron gas in this quantum well structure arises from the suppressed hybridization between Re/Fe d states and unoccupied Ti d states, and it is further strengthened by polar fields for the (111) direction. This mechanism, distinct from the polar catastrophe, leads to an order of magnitude stronger confinement of the 2D electron gas than that at the LaAlO3/SrTiO3 interface. We further show low-energy bands of (111) heterostructure display nontrivial topological character. Our work opens up the possibility of realizing ultra-thin spintronic devices. Journal Ref: Phys. Rev. B 92, 161106(R) (2015) S.B. and T.S.D thank Department of Science and Technology, India for the support through Thematic Unit of Excellence. AP was supported by NSERC (Canada).

Coexistence of superconductivity and magnetism in Er{sub 2}Ba{sub 4}Cu{sub 7}O{sub 14.3}

Energy Technology Data Exchange (ETDEWEB)

Mesot, J; Boettger, G; Fischer, P [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Suard, E [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Berastegui, P

1997-09-01

The Er{sub 2}Ba{sub 4}Cu{sub 7}O{sub 14+{delta}} compounds show a very interesting behaviour upon removing of oxygen. Although the samples remain superconducting when going from {delta}=1 to {delta}=0, our low temperature elastic and inelastic measurements ({delta}<14.3) strongly indicate that a magnetic field is present at the Er site. Such a field could be generated by magnetically active Cu atoms in one of the neighbouring CuO{sub 2} planes. (author) 3 figs., 2 refs.

Classical theory of atom-surface scattering: The rainbow effect

Science.gov (United States)

Miret-Artés, Salvador; Pollak, Eli

2012-07-01

The scattering of heavy atoms and molecules from surfaces is oftentimes dominated by classical mechanics. A large body of experiments have gathered data on the angular distributions of the scattered species, their energy loss distribution, sticking probability, dependence on surface temperature and more. For many years these phenomena have been considered theoretically in the framework of the “washboard model” in which the interaction of the incident particle with the surface is described in terms of hard wall potentials. Although this class of models has helped in elucidating some of the features it left open many questions such as: true potentials are clearly not hard wall potentials, it does not provide a realistic framework for phonon scattering, and it cannot explain the incident angle and incident energy dependence of rainbow scattering, nor can it provide a consistent theory for sticking. In recent years we have been developing a classical perturbation theory approach which has provided new insight into the dynamics of atom-surface scattering. The theory includes both surface corrugation as well as interaction with surface phonons in terms of harmonic baths which are linearly coupled to the system coordinates. This model has been successful in elucidating many new features of rainbow scattering in terms of frictions and bath fluctuations or noise. It has also given new insight into the origins of asymmetry in atomic scattering from surfaces. New phenomena deduced from the theory include friction induced rainbows, energy loss rainbows, a theory of super-rainbows, and more. In this review we present the classical theory of atom-surface scattering as well as extensions and implications for semiclassical scattering and the further development of a quantum theory of surface scattering. Special emphasis is given to the inversion of scattering data into information on the particle-surface interactions.

Interactions between nitrogen molecules and barium atoms on Ru (0001) surface

International Nuclear Information System (INIS)

Zhao Xinxin; Mi Yiming; Xu Hongxia; Wang Lili; Ren Li; Tao Xiangming; Tan Mingqiu

2011-01-01

We had performed first principles calculations on interactions between nitrogen molecules and barium atoms on Ru (0001) surface using density function theory methods. It was shown that effects of barium atoms weakened the bond strength of nitrogen molecules. The bond length of nitrogen molecule increases from 0.113 nm on Ru (001)-N 2 to 0.120 nm on Ru (001)-N 2 /Ba surface. While stretch vibrational frequency of nitrogen molecule decreased from 2222 cm -1 and charge transfer toward nitrogen molecule increased from 0.3 e to 1.1 e. Charge was mainly translated from 6 s orbitals of barium atoms to 4 d orbitals of substrate, which enhanced the hybridization between 4 d and 2 π orbitals and increased the dipole moment of 5 σ and d π orbitals of nitrogen molecule. The molecular dipole moment of nitrogen molecule was increased by -0.136 e Anstrom. It was suggested that barium had some characters to be an electronic promoter on the process of activating nitrogen molecules on Ru (0001) surface. (authors)

Inner shell ionization by incident nuclei

International Nuclear Information System (INIS)

Hansteen, J.M.

1974-10-01

The atomic Coulomb excitation process induced by impinging heavy charged particles such as protons, deuterons, α-particles and complex heavy ions is reviewed. Recent experimental and theoretical efforts have led toimproved understanding of the atomic Coulomb excitation as well as to discovery of new types of ionization mechanisms. The following models are mentioned: the Plane Wave Born Approximation (PWBA); theeeeeeeeeeeee modified PWBA model; the Binary Encounter Approximation (BEA); the Semi-Classical Approximation (SCA); the Perturbed-Stationary-State model (PSS). The structure of the SCA model is more thoroughly treated. Experimental results on single Coulomb ionizations of the K-, L-, and M-shells, and of the connected sub-shells by protons are compared with predictions. Most calculations are based on straight line projectile paths and non-relativistic hydrogen-like target electron wave functions. The BEA model and the SCA model seem to work reasonably well for multiple Coulomb ionizations by stripped light ions. Background effects in ion-atom collisions are commented upon. Future aspects of atomic Coulomb excitation by incident nuclei and ions are discussed. The interplay between Coulomb induced processes and united atom phenomena is especially mentioned. The simple ionization models have yielded valuable insights but it is suggested that this branch of collision physics has reached a turning point where new and more advanced and unifying models are needed. (JIW)

X-ray holography. Atoms in three dimensions

International Nuclear Information System (INIS)

Tegze, M.

2005-01-01

The principles of atomic resolution X-ray holography was elaborated in 1991. X-ray photons scatter thousand times less on atoms than electrons of the same wavelength. As a result, both free path and penetration depth are higher which giver information about the bulk material. X-ray holography is realized by irradiating the single crystal sample with radiation from external X-ray source. The incident radiation is ionizing the atoms of the sample to emit fluorescent radiation. The angle dependence of the fluorescent radiation results an image containing the hologram. The hologram itself is extremely small compared to the background that needs 10 10 capturing photons to recover image. Using Thomas Gog's method and synchrotron radiation the X-ray holography becomes more usable, but the method still needs refining both experimentally and theoretically. (TRA)

Dynamics of photoexcited Ba{sup +} cations in {sup 4}He nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Leal, Antonio; Pi, Martí [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Zhang, Xiaohang; Drabbels, Marcel [Laboratoire de Chimie Physique Moléculaire, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Barranco, Manuel [Departament ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France); Cargnoni, Fausto [Istituto di Scienze e Tecnologie Molecolari (ISTM), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano (Italy); Hernando, Alberto [Social Thermodynamics Applied Research (SThAR), EPFL Innovation Park, Bâtiment C, CH-1015 Lausanne (Switzerland); Mateo, David [Department of Chemistry and Biochemistry, California State University at Northridge, Northridge, California 91330 (United States); Mella, Massimo [Dipartimento di Scienza ed Alta Tecnologia, Università degli Studi dell’Insubria, via Valleggio 11, 22100 Como (Italy)

2016-03-07

We present a joint experimental and theoretical study on the desolvation of Ba{sup +} cations in {sup 4}He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba{sup +} cations and Ba{sup +}He{sub n} exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba{sup +} He{sub n} exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba{sup +}. In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba{sup +} cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba{sup +} cations or exciplexes, even when relaxation pathways to lower lying states are included.

Thermoelectric properties of doped BaHfO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Dixit, Chandra Kr., E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Dr. Shakuntala Misra National Rehabilitation University, Lucknow-229001, U.P India (India); Bhamu, K. C. [Department of Physics, Goa University, Goa-403 206 (India); Sharma, Ramesh, E-mail: ckparadise@gmail.com, E-mail: sharmarameshfgiet@gmail.com [Dept. of Physics, Feroze Gandhi Institute of Engineering & Technology, Raebareli-229001, U.P India (India)

2016-05-06

We have studied the structural stability, electronic structure, optical properties and thermoelectric properties of doped BaHfO{sub 3} by full potential linearized augmented plane wave (FP-LAPW) method. The electronic structure of BaHfO{sub 3} doped with Sr shows enhances the indirect band gaps of 3.53 eV, 3.58 eV. The charge density plots show strong ionic bonding in Ba-Hf, and ionic and covalent bonding between Hf and O. Calculations of the optical spectra, viz., the dielectric function, refractive index and extinction coefficient are performed for the energy range are calculated and analyzed. Thermoelectric properties of semi conducting are also reported first time. The doped BaHfO{sub 3} is approximately wide band gap semiconductor with the large p-type Seebeck coefficient. The power factor of BaHfO{sub 3} is increased with Sr doping, decreases because of low electrical resistivity and thermal conductivity.

Operability test procedure for 211BA flow proportional sampler

International Nuclear Information System (INIS)

Weissenfels, R.D.

1994-01-01

The purpose of this operability test procedure (OTP) is to verify the 211-BA flow proportional sampler system and components function correctly as intended by design. System test will include the sampling system, all associated instrumentation, and Facility Process Monitor and Control System (FPMCS). The combined chemical sewer stream from B Plant flows through sump 211BA-SMP-01 located in 211-BA and is continuously monitored for gamma and beta radiation and pH. 211-BA has been upgraded to include a flow proportional sampler. A specified sample volume will be withdrawn at programmed intervals from the 211BA sump and deposited in a 19 liter plastic carboy. The sampler will be programmed per the vendor installation and operations manual by B Plant instrument maintenance personnel. Samples will be taken during five consecutive sample cycles with the sample volumes and sample frequencies recorded for comparison purposes. Additional tests related to the sampler include the alarm circuitry for loss of power and failure to obtain sample

Ba-bah on tulnud / Liina Jänes

Index Scriptorium Estoniae

Jänes, Liina, 1977-

2005-01-01

Eesti noori disainereid-sisearhitekte ühendavast disainiagentuurist Ba-bah, selle eesmärgist. Agentuuri juhib Veiko Jääger. Mais 2005 Disaini- ja Arhitektuurigaleriis toimunud Ba-bahi avanäitusest, kus oli väljas töid EKA sisearhitektuuri, klaasi-, ehte- ja sepakunsti eriala üliõpilastelt ning metallmööbli valmistajalt Kalle Pruudenilt

The microscopic twins and their crystal phase in the high Tc Y-Ba-Cu-O and Dy-Ba-Cu-O superconductive ceramics

International Nuclear Information System (INIS)

Zu, Z.J.; Chen, Y.L.

1988-01-01

Most consider that the structure of Y-Ba- Cu-O and Dy-Ba-Cu-O stable superconductive crystals with high Tc is associated with the right-angled phase. The superconductivity is closely connected with the right-angled character of the crystalline texture; the better the right- angled character, the better the superconductivity. From statistical investigations of examples the authors have discovered that most of the Y-Ba-Cu-O and Dy-Ba-Cu-O superconductivity with high Tc ceramic crystals is in the monoclinic phase, which, consists of microscopic, lamellar, single twins. The long-columnar grains consisting of lamellar twin slabs show the optical characteristics of right-angled phase. The microscopic twinning and grain morphologies are summarized in this paper

Electronic Structure of the Double Perovskite Ba2Er(Nb,Sb)O6

International Nuclear Information System (INIS)

Rebaza, A V Gil; Toro, C E Deluque; Téllez, D A Landínez; Roa-Rojas, J

2014-01-01

In this work, we present a detailed study of the structural and the electronic structure of the double perovskite Ba 2 Er(Nb,Sb)O 6 . All calculations were performed with the Full-Potential Linear Augmented Plane Wave method (FP-LAPW) based on the Density Functional Theory (DFT). From the minimization of energy as a function of volume using the Murnaghan's state equation has been obtained the equilibrium lattice parameter and the bulk modulus of these compounds. The study of the electronic structure was based in the analysis of the electronic density of states (DOS), and the density of charge, showing that these compounds have a total magnetic moment of 3.0 μ B per formula unit due to Er atoms

Local manifestations of a static magnetoelectric effect in nanostructured BaTiO3-BaFe12O9 composite multiferroics

Science.gov (United States)

Trivedi, Harsh; Shvartsman, Vladimir V.; Lupascu, Doru C.; Medeiros, Marco S. A.; Pullar, Robert C.; Kholkin, Andrei L.; Zelenovskiy, Pavel; Sosnovskikh, Andrey; Shur, Vladimir Ya.

2015-02-01

A study on magnetoelectric phenomena in the barium titanate-barium hexaferrite (BaTiO3-BaFe12O19) composite system, using high resolution techniques including switching spectroscopy piezoresponse force microscopy (SSPFM) and spatially resolved confocal Raman microscopy (CRM), is presented. It is found that both the local piezoelectric coefficient and polarization switching parameters change on the application of an external magnetic field. The latter effect is rationalized by the influence of magnetostrictive stress on the domain dynamics. Processing of the Raman spectral data using principal component analysis (PCA) and self-modelling curve resolution (SMCR) allowed us to achieve high resolution phase distribution maps along with separation of average and localized spectral components. A significant effect of the magnetic field on the Raman spectra of the BaTiO3 phase has been revealed. The observed changes are comparable with the classical pressure dependent studies on BaTiO3, confirming the strain mediated character of the magnetoelectric coupling in the studied composites.

The BaBar silicon vertex tracker

International Nuclear Information System (INIS)

Bozzi, C.; Carassiti, V.; Ramusino, A. Cotta; Dittongo, S.; Folegani, M.; Piemontese, L.; Abbott, B.K.; Breon, A.B.; Clark, A.R.; Dow, S.; Fan, Q.; Goozen, F.; Hernikl, C.; Karcher, A.; Kerth, L.T.; Kipnis, I.; Kluth, S.; Lynch, G.; Levi, M.; Luft, P.; Luo, L.; Nyman, M.; Pedrali-Noy, M.; Roe, N.A.; Zizka, G.; Roberts, D.; Barni, D.; Brenna, E.; Defendi, I.; Forti, A.; Giugni, D.; Lanni, F.; Palombo, F.; Vaniev, V.; Leona, A.; Mandelli, E.; Manfredi, P.F.; Perazzo, A.; Re, V.; Angelini, C.; Batignani, G.; Bettarini, S.; Bondioli, M.; Bosi, F.; Calderini, G.; Carpinelli, M.; Dutra, F.; Forti, F.; Gagliardi, D.; Giorgi, M.A.; Lusiani, A.; Mammini, P.; Morganti, M.; Morsani, F.; Paoloni, E.; Profeti, A.; Rama, M.; Rampino, G.; Rizzo, G.; Sandrelli, F.; Simi, G.; Triggiani, G.; Tritto, S.; Vitale, R.; Burchat, P.; Cheng, C.; Kirkby, D.; Meyer, T.; Roat, C.; Bona, M.; Bianchi, F.; Daudo, F.; Girolamo, B. Di; Gamba, D.; Giraudo, G.; Grosso, P.; Romero, A.; Smol, A.; Trapani, P.; Zanin, D.; Bosisio, L.; Ricca, G. Della; Lanceri, L.; Pompili, A.; Poropat, P.; Prest, M.; Rastelli, C.; Vallazza, E.; Vuagnin, G.; Hast, C.; Potter, E.P.; Sharma, V.; Burke, S.; Callahan, D.; Campagnari, C.; Dahmes, B.; Eppich, A.; Hale, D.; Hall, K.; Hart, P.; Kuznetsova, N.; Kyre, S.; Levy, S.; Long, O.; May, J.; Richman, J.; Verkerke, W.; Witherell, M.; Beringer, J.; Eisner, A.M.; Frey, A.; Grillo, A.; Grothe, M.; Johnson, R.; Kroeger, W.; Lockman, W.; Pulliam, T.; Rowe, W.; Schmitz, R.; Seiden, A.; Spencer, E.; Turri, M.; Wilder, M.; Charles, E.; Elmer, P.; Nielsen, J.; Orejudos, W.; Scott, I.; Walsh, J.; Zobernig, H.

2000-01-01

The BaBar Silicon Vertex Tracker (SVT) is designed to provide the high-precision vertexing necessary for making measurements of CP violation at the SLAC B-Factory PEP-II. The instrument consists of five layers of double-sided silicon strip detectors and has been installed in the BaBar experiment and taking colliding beam data since May 1999. An overview of the design as well as performance and experience from the initial running will be presented

Genome Sequence of African Swine Fever Virus BA71, the Virulent Parental Strain of the Nonpathogenic and Tissue-Culture Adapted BA71V.

Science.gov (United States)

Rodríguez, Javier M; Moreno, Leticia Tais; Alejo, Alí; Lacasta, Anna; Rodríguez, Fernando; Salas, María L

2015-01-01

The strain BA71V has played a key role in African swine fever virus (ASFV) research. It was the first genome sequenced, and remains the only genome completely determined. A large part of the studies on the function of ASFV genes, viral transcription, replication, DNA repair and morphogenesis, has been performed using this model. This avirulent strain was obtained by adaptation to grow in Vero cells of the highly virulent BA71 strain. We report here the analysis of the genome sequence of BA71 in comparison with that of BA71V. They possess the smallest genomes for a virulent or an attenuated ASFV, and are essentially identical except for a relatively small number of changes. We discuss the possible contribution of these changes to virulence. Analysis of the BA71 sequence allowed us to identify new similarities among ASFV proteins, and with database proteins including two ASFV proteins that could function as a two-component signaling network.

Hexagonal perovskites with cationic vacancies. 3. Structure determination on compounds of type Ba/sub 2/Bsub(1/3)sup(III)vacantsub(2/3)Resup(VII)O/sub 6/

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Wischert, W; Treiber, U [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

1978-09-01

Compounds of type Ba/sub 2/Bsub(1/3)sup(III)vacantsub(2/3)Resup(VII)O/sub 6/ with Bsup(III) = rare earth, Y, Sc. In belong to the group of hexagonal perovskite stacking polytypes. For Bsup(III) = Gd, Y structure determinations with powder data have been performed. The refined R' factors are 9.11% for Ba/sub 2/Gdsub(1/3)vacantsub(2/3)ReO/sub 6/ and 12.07% for Ba/sub 2/Ysub(1/3)vacantsub(2/3)ReO/sub 6/. The structure represents a rhombohedral 12 L type (space group R3m) with the sequence hhcchhcchhcc. The lattice contains groups of three octahedra connected by common faces which are linked together by a single octahedron via common vertices. In the block of three face-sharing octahedra the central octahedral lattice site is vacant and the two outer positions are occupied by the rhenium atoms. According to this distribution direct contact of occupied face-sharing octahedra is absent.

Praseodymium valency from crystal structure in Pr-Ba-Cu-O and (Y-Pr)-Ba-Cu-O single crystals

International Nuclear Information System (INIS)

Collin, G.; Albouy, P.A.; Monod, P.; Ribault, M.

1990-01-01

The substitution of Pr to Y leads to materials with a general formula (Y 1-v Pr v ) (Ba 2-x Pr x ) (Cu 3-y vac y ) O 6+x/2-y+z and with a structural transition around v + x' ∼ 0.5. For v + x 0.5 the crystals are tetragonal, La 1.5 Ba 1.5 Cu 3 O 7±z type, with the characteristic tri-twinning of this phase. The Pr valency, in the range 3-3.2 + depending on preparation conditions, is determined from interatomic distances. Orthorhombic crystals of Pr Ba Cu O prepared at high temperatures exhibit a high amount of defects, y ∼ 0.25 on the Cu(1) site and are semiconductors with a T -1/4 activation law attributed to the praseodymium valence fluctuation

Structural evolution of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} using a series of Ba(Ti{sub 1−5x}Nb{sub 4x})O{sub 3} solid solutions

Energy Technology Data Exchange (ETDEWEB)

Barrientos Hernández, F.R., E-mail: frbh68@hotmail.com [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Lira Hernández, I.A. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Industrial Engineering Department, Technological Institute of Pachuca, Road México-Pachuca km. 87.5, Pachuca de Soto zip code 42080, Hidalgo (Mexico); Gómez Yáñez, C. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Arenas Flores, A. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico); Cabrera Sierra, R. [Department of Metallurgical and Materials Engineering, ESIQIE, National Polytechnic Institute, UPALM, Zacatenco, Mexico City, zip code 07738 (Mexico); Pérez Labra, M. [Academic Area of Earth Sciences and Materials, Autonomous University of Hidalgo State, Road Pachuca-Tulancingo km 4.5, Mineral de la Reforma zip code 42184, Hidalgo (Mexico)

2014-01-15

Highlights: • The evolution phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} was obtained through the mechanism Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3}. • Addition of niobium can accelerate grain growth of BaTiO{sub 3} ceramics. • Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} presents a dielectric loss of 0.0035 and permittivity value of 54.6. • Electrical measurements showed that Nb{sup 5+} content drops Curie temperature. • Samples with x ⩾ 0.0625 shows an insulating behavior. -- Abstract: In this work, the structural evolution of hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} by adding Nb{sub 2}O{sub 5} to perovskite structure of BaTiO{sub 3} was investigated. The compositions Ba(Ti{sub 1-5x}Nb{sub 4x})O{sub 3} ceramics, with 0.00025 ⩽ x ⩽ 0.125 were prepared by the conventional solid state route in air atmosphere, the powders precursors, BaTiO{sub 3}, BaCO{sub 3} and Nb{sub 2}O{sub 5}, were mixed in stoichiometric proportions and ground in a ball mill using alumina balls and acetone. The mixed powders were calcined at temperatures up to 1500 °C. The phase transformation of Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} from BaTiO{sub 3} was studied by DRX, Raman spectroscopy, SEM, electrical measurements (relative permittivity and P–E hysteresis loops); Rietveld’s refinement was used to structurally characterize the samples. For the devices obtained capacitance was measured at 1 kHz; with these values we calculated the relative permittivity. The samples show typical P–E hysteresis loops at room temperature accompanied by saturation polarization (Ps) and remnant polarization (Pr). The DRX and Rietveld’s refinement results show x ⩽ 0.01 has a ferroelectric behavior. When the doped level is increased x ⩾ 0.02, a peak displacement is observed, this is due to the phase transformation of tetragonal to cubic into the unit cell. Finally, with x = 0.125 the crystal structure transforms to the characteristic hexagonal phase Ba{sub 8}Ti{sub 3}Nb{sub 4}O{sub 24} which

Flora da Paraíba, Brasil: Loganiaceae Flora of Paraíba, Brazil: Loganiaceae

Directory of Open Access Journals (Sweden)

Kiriaki Nurit

2005-06-01

Full Text Available Neste trabalho apresenta-se o tratamento taxonômico da família Loganiaceae, como parte do projeto "Flora da Paraíba", que vem sendo realizado com o objetivo de identificar e catalogar as espécies da flora local. Realizouse coletas e observações de campo para as identificações, descrições e ilustrações botânicas que foram efetuadas após estudos morfológicos, com o auxílio da bibliografia especializada, complementados pela análise de fotos de tipos, espécimes dos herbários EAN, JPB e IPA, e comparação com material identificado por especialistas. Registrou-se para a Paraíba quatro espécies: Spigelia anthelmia L., com ampla distribuição, e três espécies de Strychnos, somente coletadas em remanescentes de Mata Atlântica, S. atlantica Krukoff & Barneby, S. parvifolia A. DC. e S. trinervis (Vell. Mart.This work constitutes a taxonomic treatment of the Loganiaceae family as part of the project "Flora da Paraíba", which have been carried out with the objective to identify and catalogue the species of the local flora. The botanical identifications and illustrations were made by morphological studies supported by bibliography, analysis of the types, specimens from herbaria EAN, JPB and IPA, and comparison with samples previously identified by specialists, complemented by field observations. Four species of Loganiaceae belonging two genera were found in State of Paraíba: Spigelia anthelmia L. that has wide distribution and three species of Strychnos, found on remains of Atlantic forest, which are S. atlantica Krukoff & Barneby, S. parvifolia A. DC. and S. trinervis (Vell. Mart.

Optical characteristics of BaGa{sub 2}S{sub 4}:Ho{sup 3+} and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals

Energy Technology Data Exchange (ETDEWEB)

Choe, Sung-Hyu [Chosun University, Kwangju (Korea, Republic of); Jin, Moon-Seog [Dongshin University, Naju (Korea, Republic of); Kim, Wha-Tek [Chonnam National University, Kwangju (Korea, Republic of)

2005-11-15

BaGa{sub 2}S{sub 4}, BaGa{sub 2}S{sub 4}:Ho{sup 3+}, BaGa{sub 2}Se{sub 4}, and BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the single crystals were investigated in the temperature region from 11 K to 300 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Two broad emission bands were observed in the photoluminescence spectra of the single crystals. These bands were attributed to donor-acceptor pair recombinations. Sharp emission peaks were observed in the BaGa{sub 2}S{sub 4}:Ho{sup 3+} and the BaGa{sub 2}Se{sub 4}:Ho{sup 3+} single crystals and were assigned to radiation recombination between split Stark levels of Ho{sup 3+}.

The electron-atom ionization problem

International Nuclear Information System (INIS)

McCarthy, I.E.

1995-02-01

Methods of calculating electron-atom ionization as a three-body problem with Coulomb boundary conditions are considered. In the absence of a fully-valid computational method for a time-independent experiment the approximation is made that the incident electron experiences a screened potential. Approximations involving a final state that obeys the three-body Coulomb boundary condition are compared with the distorted-wave Born approximation and the convergent close-coupling method. 24 refs., 6 figs

Adaptive strain prompting a pseudo-morphotropic phase boundary in ferroelectric (1-x ) Na0.5Bi0.5TiO3-x BaTiO3

Science.gov (United States)

Datta, K.; Neder, R. B.; Richter, A.; Göbbels, M.; Neuefeind, J. C.; Mihailova, B.

2018-05-01

The understanding of the atomistic origin of the morphotropic phase boundary (MPB) occurring in composition-temperature phase diagrams of ferroelectric solid solutions is a key topic in material science because materials often exhibit anomalous properties at the MPB. Here we reveal mesoscopic-scale structural correlations for a leading Pb-free ferroelectric system, (1 -x ) Na0.5Bi0.5TiO3-x BaTiO3 (NBT-x BT ), by examining atomic pair distribution functions and Raman scattering data at ambient conditions. We demonstrate that the amplification of the piezoelectric properties of NBT-x BT at the MPB are predominantly driven by an easy switchability resulting from a progressive decoupling between strain and polarization as the Ba content increases from zero to the critical MPB composition. It was observed that as Ba content increases towards MPB, competing local correlations, such as A-site chemical order, antiferrodistortive correlations of correlated BO6 tilts, and antipolar Bi shifts, are reduced, which in turn renders favorable conditions for easy switching of local dipoles under external fields. In addition, the evolving characteristics of the atomic dynamics as a function of composition suggest that the local potential functions of the cations are not completely flat at the MPB. Altogether, our results reveal atomistic mechanisms responsible for the observed elevated MPB properties in the case of NBT-x BT which imply that the so-called MPB of NBT-x BT should not be categorized as originally introduced for Pb-containing solid solutions.

Leukemia in Hiroshima atomic bomb survivors

Energy Technology Data Exchange (ETDEWEB)

Heyssel, R; Brill, A B; Woodbury, L A; Nishimura, Edwin T; Ghose, Tarunendu; Hoshino, Takashi; Yamasaki, Mitsuru

1959-03-01

This report is intended to provide the basic data pertinent to the leukemia experience observed in the survivors of the Hiroshima atomic explosion. Many of the conclusions in this report are tentative. The one clear fact to emerge is that radiation increases the occurrence rate of leukemia and that the magnitude of increase is dependent on dose received. Additional observations can be made, which, while not definitive in themselves, seem to complement each other, and are corroborated by other experiences in radiation biology. From the data a linear relationship between dose and incidence of leukemia is found. The shape of the relation in the lower dose range is not known with certainty. An approximate minimum time for the appearance of leukemia following radiation is 3 years or less. The data suggest that the time of maximum risk of leukemia may be dependent on the dose of radiation received. In this group the mean latent period is found to lie in the interval between 4 and 8 years following exposure. The length of time during which the increased incidence of leukemia persists is not known. The incidence of the acute leukemias and of chronic granulocytic leukemia is increased in the exposed survivors. The chronic granulocytic variety is disproportionately increased in Japanese survivors of the atomic bomb. No effect of radiation on monocytic or chronic lymphatic leukemia incidence is noted. Aplastic anemia, polycythemia vera, and myelofibrosis have been investigated. Myelofibrosis is the only one of this group of diseases in which a suggestive relation to radiation exposure is apparent. The natural history of leukemia following radiation does not seem to differ from that of the spontaneously occurring variety. 17 references, 5 figures, 38 tables.

Analysis of oxygen binding-energy variations for BaO on W

Science.gov (United States)

Haas, G. A.; Shih, A.; Mueller, D.; Thomas, R. E.

Interatomic Auger analyses have been made of different forms of BaO layers on W substrates. Variations in Auger spectroscopy energies of the Ba4dBa5pO2p interatomic Auger transition were found to be largely governed by the O2p binding energy of the BaO adsorbate. This was illustrated by comparing results of the Auger data values with values derived from O2p binding energies using ultraviolet photoelectron spectroscopy. Very good agreement was observed not only for the W substrate but also for the W substrate which showed two oxygen-induced electronics state. Variations in binding energy were noted for different states of BaO lattice formation and for different amounts of oxidation, ranging from the transition of Ba to BaO and continuing to the BaO 2 stoichiometry and beyond. Effects were also reported for adsorbate alignment and thermal activation (i.e., reduction) of the oxidized state. An empirical relationship was found suggesting that the more tightly bound the O2p states of the BaO adsorbate were, the lower its work function would be. This link between binding energy and work function was observed to be valid not only for cases of poisoning by oxidation, but held as well during reactivation by the subsequent reduction of the oxide. In addition, this relationship also appeared to predict the low work function obtained through the introduction of substances such as Sc to the BaO-W system. Possible qualitative reasons which might contribute to this are discussed in terms of enhanced dipole effects and shifts in band structure.

Electronic relaxation dynamics of a metal atom deposited on argon cluster

International Nuclear Information System (INIS)

Awali, Slim

2014-01-01

This thesis is a study on the interaction between electronically excited atomic states and a non-reactive environment. We have theoretically and experimentally studied situations where a metal atom (Ba or K) is placed in a finite size environment (argon cluster). The presence of the medium affects the electronic levels of the atom. On the other side, the excitation of the atom induces a relaxation dynamics of the electronic energy through the deformation of the cluster. The experimental part of this work focuses on two aspects: the spectroscopy and the dynamics. In both cases a first laser electronically excites the metal atom and the second ionizes the excited system. The observable is the photoelectron spectrum recorded after photoionization and possibly information on the photoion which are also produced. This pump/probe technique, with also two lasers, provide the ultrafast dynamic when the lasers pulses used are of ultrashort (60 fs). The use of nanosecond lasers leads to resonance spectroscopic measurement, unresolved temporally, which give information on the position of the energy levels of the studied system. From a theoretical point-of-view, the excited states of M-Ar n were calculated at the ab initio level, using large core pseudo-potential to limit the active electrons of the metal to valence electrons. The study of alkali metals (potassium) is especially well adapted to this method since only one electron is active. The ab-initio calculation and a Monte-Carlo simulation where coupled to optimize the geometry of the KAr n (n = 1-10) cluster when K is in the ground state of the neutral and the ion, or excited in the 4p or 5s state. Calculations were also conducted in collaboration with B. Gervais (CIMAP, Caen) on KAr n clusters having several tens of argon atoms. Absorption spectra were also calculated. From an experimental point-of-view, we were able to characterize the excited states of potassium and barium perturbed by the clusters. In both cases a

Laser Assisted Free-Free Transition in Electron - Atom Collision

Science.gov (United States)

Sinha, C.; Bhatia, A. K.

2011-01-01

Free-free transition is studied for electron-Hydrogen atom system in ground state at very low incident energies in presence of an external homogeneous, monochromatic and linearly polarized laser field. The incident electron is considered to be dressed by the laser in a non perturbative manner by choosing the Volkov solutions in both the channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the effect of electron exchange, short range as well as of the long range interactions. Laser assisted differential as well as elastic total cross sections are calculated for single photon absorption/emission in the soft photon limit, the laser intensity being much less than the atomic field intensity. A strong suppression is noted in the laser assisted cross sections as compared to the field free situations. Significant difference is noted in the singlet and the triplet cross sections.

Optical energy gaps and photoluminescence peaks of BaGa2S4:Er3+ and BaGa2Se4:Er3+ single crystals

International Nuclear Information System (INIS)

Choe, Sung-Hyu; Jin, Moon-Seog; Kim, Wha-Tek

2005-01-01

BaGa 2 S 4 :Er 3+ and BaGa 2 Se 4 :Er 3+ single crystals were grown by using the chemical transport reaction method. The optical energy gaps of the BaGa 2 S 4 :Er 3+ and the BaGa 2 Se 4 :Er 3+ single crystals were found to be 4.045 eV and 3.073 eV, respectively, at 11 K. The temperature dependence of the optical energy gap was well fitted by the Varshni equation. Sharp emission peaks were observed in the photoluminescence spectra of the single crystals and assigned to radiation recombination between split Stark levels of the Er 3+ ion.

Laser fluorescence spectroscopy of sputtered uranium atoms

International Nuclear Information System (INIS)

Wright, R.B.; Pellin, M.J.; Gruen, D.M.; Young, C.E.

1979-01-01

Laser induced fluorescence (LIF) spectroscopy was used to study the sputtering of 99.8% 238 U metal foil when bombarded by normally incident 500 to 3000 eV Ne + , Ar + , Kr + , and O 2 + . A three-level atom model of the LIF processes is developed to interpret the observed fluorescent emission from the sputtered species. The model shows that close attention must be paid to the conditions under which the experiment is carried out as well as to the details of the collision cascade theory of sputtering. Rigorous analysis shows that when properly applied, LIF can be used to investigate the predictions of sputtering theory as regards energy distributions of sputtered particles and for the determination of sputtering yields. The possibility that thermal emission may occur during sputtering can also be tested using the proposed model. It is shown that the velocity distribution (either the number density or flux density distribution, depending upon the experimental conditions) of the sputtered particles can be determined using the LIF technique and that this information can be used to obtain a description of the basic sputtering mechanisms. These matters are discussed using the U-atom fluorescence measurements as a basis. The relative sputtering yields for various incident ions on uranium were also measured for the first time using the LIF technique. A surprisingly high fraction of the sputtered uranium atoms were found to occupy the low lying metastable energy levels of U(I). The population of the sputtered metastable atoms were found approximately to obey a Boltzman distribution with an effective temperature of 920 +- 100 0 K. 41 references

Preparation of Ba1-xSrxWO4 and Ba1-xCaxWO4 films on tungsten plate by mechanically assisted solution reaction at room temperature

International Nuclear Information System (INIS)

Rangappa, Dinesh; Fujiwara, Takeshi; Watanabe, Tomoaki; Yoshimura, Masahiro

2008-01-01

Preparation of the alkaline earth tungstate films such as Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 on the tungsten substrate was studied with a simple solution process assisted with the ball rotation at room temperature. The solid solution formation and limitations, the effect of oxidizing agent H 2 O 2 and alkaline earth ions concentration on the dissolution of W substrate and the growth of Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were studied in detail. The ball rotation assistance plays a very important role to enhance the dissolution of the W substrate and mass transport of the reactant species such as alkaline earth ions and WO 4 2- ions onto the solid/solution interface region, where precipitation occurs. Therefore, the rate of film formation was accelerated by the ball rotation assistance to the reaction system. Ba-rich Ba 1-x Sr x WO 4 and Ba 1-x Ca x WO 4 films were formed without high energy or high temperature treatment

The mechanically induced structural disorder in barium hexaferrite, BaFe12O19, and its impact on magnetism

CERN Document Server

Šepelák, V; Witte, R; Röder, J; Menzel, D; Schuster, R H; Hahn, H; Heitjans, P; Becker, K-D

2014-01-01

The response of the structure of the M-type barium hexaferrite (BaFe12O19) to mechanical action through high-energy milling and its impact on the magnetic behaviour of the ferrite are investigated. Due to the ability of the Fe-57 Mossbauer spectroscopic technique to probe the environment of the Fe nuclei, a valuable insight on a local atomic scale into the mechanically induced changes in the hexagonal structure of the material is obtained. It is revealed that the milling of BaFe12O19 results in the deformation of its constituent polyhedra (FeO6 octahedra, FeO4 tetrahedra and FeO5 triangular bi-pyramids) as well as in the mechanically triggered transition of the Fe3+ cations from the regular 12k octahedral sites into the interstitial positions provided by the magnetoplumbite structure. The response of the hexaferrite to the mechanical treatment is found to be accompanied by the formation of a non-uniform nanostructure consisting of an ordered crystallite surrounded/separated by a structurally disordered surfac...

Ca doping of TSMTG-YBa2Cu3O7-δ/Y2BaCuO5 composites

International Nuclear Information System (INIS)

Delorme, F.; Harnois, C.; Monot-Laffez, I.; Marinel, S.

2002-01-01

Calcium doped YBa 2 Cu 3 O 7-δ /Y 2 BaCuO 5 bulk samples have been synthesised by the top-seeding-melt-texture growth (TSMTG) process up to 1 wt.% of CaCO 3 . Calcium additions up to 0.25 wt.% of CaCO 3 do not change the decomposition temperature whereas additions of 1 wt.% of CaCO 3 lead to an increase of the decomposition temperature of about 10 deg. C. This difference is not important enough to change the thermal cycle used to process YBa 2 Cu 3 O 7-δ undoped bulk samples. Microstructure studies show that no precursor or secondary phases containing calcium are present in the samples. Energy dispersive spectroscopy analyses have shown that Ca is present both in the YBa 2 Cu 3 O 7-δ matrix and the Y 2 BaCuO 5 particles. The position of the calcium atoms in the superconducting matrix is discussed. The calcium doped samples present slightly depressed critical temperatures but drastically depressed critical current densities

Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2

KAUST Repository

Nazir, Safdar

2011-01-31

Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge transfer effects on the Fermi surface of Ba0.5K 0.5Fe2As2

KAUST Repository

Nazir, Safdar; Zhu, Zhiyong; Schwingenschlö gl, Udo

2011-01-01

Ab-initio calculations within density functional theory are performed to obtain a more systematic understanding of the electronic structure of iron pnictides. As a prototypical compound we study Ba0.5K 0.5Fe2As2 and analyze the changes of its electronic structure when the interaction between the Fe2As 2 layers and their surrounding is modified. We find strong effects on the density of states near the Fermi energy as well as the Fermi surface. The role of the electron donor atoms in iron pnictides thus cannot be understood in a rigid band picture. Instead, the bonding within the Fe2As 2 layers reacts to a modified charge transfer from the donor atoms by adapting the intra-layer Fe-As hybridization and charge transfer in order to maintain an As3- valence state. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

X-ray photoemission studies of Zn doped Cu1-xTl xBa2Ca2Cu 3-yZn yO10-δ (y = 0, 2.65) superconductors

International Nuclear Information System (INIS)

Khan, Nawazish A.; Mumtaz, M.; Ahadian, M.M.; Iraji-zad, Azam

2007-01-01

The X-ray photoemission (XPS) measurements of Cu 1-x Tl x Ba 2 Ca 2 Cu 3-y Zn y O 10-δ (y = 0, 2.65) superconductors have been performed and compared. These studies revealed that the charge state of thallium in the Cu 0.5 Tl 0.5 Ba 2 O 4-δ charge reservoir layer in Zn doped samples is Tl 1+ , while it is a mix of Tl 1+ and Tl 2+ in Zn free samples. The binding energy of Ba atoms in the Zn doped samples is shifted to higher energy, which when considered along with the presence of Tl 1+ suggested that it more efficiently directed the carriers to ZnO 2 and CuO 2 planes. The evidence of improved inter-plane coupling witnessed in X-ray diffraction is also confirmed by XPS measurements of Ca atoms in the Zn doped samples. The shift of the valance band spectrum in these Zn doped samples to higher energies suggested that the electrons at the top edge of the valance band were tied to a higher binding energy (relative to samples without Zn doping), which most likely resulted in a much lower energy state of the system in the superconducting state. The stronger superconducting state arising out of these effects is witnessed in the form of increased T c (R 0), J c and the extent of diamagnetism in the final compound

The K-shell ionisation of atoms by relativistic protons

International Nuclear Information System (INIS)

Davidovic, D.M.; Moiseiwitsch, B.L.; Norrington, P.H.

1978-01-01

The K-shell ionisation of atoms by protons travelling with relativistic velocities is investigated using an extension of the first-order time-dependent perturbation-theory treatment of Moeller (Ann. Phys. Lpz.; 14:531 (1932)), taking Dirac plane waves for the description of the incident and scattered protons and the Darwin approximation for the relativistic wavefunctions of the K-shell atomic electrons and the ejected electron. The differential cross sections and total cross sections are calculated. Results are compared with those of earlier workers. (author)

Thermochemical investigations into the system Y-Ba-Cu-O

International Nuclear Information System (INIS)

Neuschuetz, D.; Zimmermann, E.; Hack, K.; Boudene, A.; Mohammad, A.

1992-01-01

For a consistent thermodynamic description of the quaternary system Y-Ba-Cu-O, the binary and ternary subsystems must be known. The metallic binaries and the ternary system Y-Ba-Cu have been evaluated by the authors. Discrepancies within the Cu-O system made a thorough experimental re-investigation necessary, leading to a new consistent thermodynamic data set for copper-oxygen which can now serve as a basis for the description of phase equilibria of all high temperature superconductors. Extensive experimental work on the ternaries Y-Cu-O and Ba-Cu-O, which are oxygen partial pressure dependent, revealed liquid phases down to 790degC. The ternary Y-Ba-O could be described more easily on the basis of literature values and present experimental results, because it does not contain any liquid phases at relevant temperatures. The representation of the quaternary Y-Ba-Cu-O is complicated both by its dependence on the oxygen potential and the existence of liquid oxide phases. In contrast to common practice, the present investigations had to start from Cu-free Ba-Y-O in order to avoid unknown liquid phases in the experiments. The present results being insufficient for a complete description of the quaternary system, the work is being continued within an EC joint research project. (orig.) With 84 refs., 8 tabs., 47 figs [de

Studi On Oxidation State Of U In Ba2NdUO6

International Nuclear Information System (INIS)

Firman Windarto, Hendri

1996-01-01

Ba 2 NdUO 6 is not of the important compounds that is formed from a solidification process for high level liquid waste using super high temperature method Ba 2 NdUO 6 has ordered perovskite structure. The objective of this study is to investigate oxidation state of U in Ba 2 NdUO 6 . The properties of Ba 2 NdUO 6 were observed by using Faraday-type torsion magnetometer and X-ray Photoelectron Spectrometer (XPS). The magnetic susceptibility measured in the temperature range of 4K to room temperature showed that the Ba 2 NdUO 6 is paramagnetism that obeys the Curie-Weiss law. The effective moment of Ba 2 NdUO 6 is 3.04 μB. The results of xPs spectrum showed that the peaks of U4f for Ba 2 NdUO 6 appeared exactly between binding energy of UO 2 and UO 3 . It can be concluded that Ba 2 NdUO 6 has binding energy peaks corresponding to pentavalent uranium

Calibration of LiBaF sub 3 Ce scintillator for fission spectrum neutrons

CERN Document Server

Reeder, P L

2002-01-01

The scintillator LiBaF sub 3 doped with small amounts of Ce sup + sup 3 has the ability to distinguish heavy charged particles (p, d, t, or alpha) from beta and/or gamma radiation based on the presence or absence of nanosecond components in the scintillation light output. Since the neutron capture reaction on sup 6 Li produces recoil alphas and tritons, this scintillator also discriminates between neutron induced events and beta or gamma interactions. An experimental technique using a time-tagged sup 2 sup 5 sup 2 Cf source has been used to measure the efficiency of this scintillator for neutron capture, the calibration of neutron capture pulse height, and the pulse height resolution--all as a function of incident neutron energy.

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

Energy Technology Data Exchange (ETDEWEB)

Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung; Mehio, Nada; Li, Meijun; Gill, Gary; Tsouris, Costas; Mayes, Richard T.; Saito, Tomonori; Dai, Sheng

2016-04-20

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly- (vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42-3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.

[POP-Q indication points, Aa and Ba, involve in diagnosis and prognosis of occult stress urinary incontinence complicated with pelvic organ prolapse].

Science.gov (United States)

Liu, Cheng; Wu, Wenying; Yang, Qing; Hu, Ming; Zhao, Yang; Hong, Li

2015-06-01

To investigate the correlation between pelvic organ prolapse quantitation (POP-Q) indication points and the incidence of occult stress urinary incontinence (OSUI) and its impact on prognosis. Retrospective study medical records of 93 patients with pelvic organ prolapse (POP) staged at III-IV, of which underwent pelvic reconstruction operations with Prolift system from Jan. 2007 to Sept. 2012. None of these patients had clinical manifestations of stress urinary incontinence (SUI) before surgery, and in which 44 patients were included in study group (POP complicated with OSUI) because they were identified with OSUI, another 49 patients as control group (simple POP). Follow-up and collecting datas including POP-Q, stress test, urodynamic recordings, incidence of de novo SUI, statistic analyzing by logistic regression and receiver operating characteristic curve (ROC). (1) The study group had a much higher incidence of 30% (13/44) on de novo SUI than that of control group (4%, 2/49; P < 0.01). (2) Vaginal delivery (OR = 5.327, 95% CI: 1.120-25.347), constipation (OR = 5.789, 95% CI: 1.492-22.459), preoperative OSUI (OR = 13.695, 95% CI: 2.980-62.944), anterior vaginal wall prolapse (OR = 6.115, 95% CI: 1.231-30.379) were identified as dependent risk factors for de novo SUI by logistic regression analysis. (3) For POP patients that complicated with OSUI, we chose a cutoff value of +1.5 cm for Aa point as the threshold to predicting incidence of de novo SUI according to ROC curve, area under the curve (AUC) was 0.889 (P < 0.05), the sensitivity reached 88.9% and specificity was 73.9%. According to ROC curve of Ba point, a cutoff value of +2.5 cm was chosen as the threshold to predicting incidence of de novo SUI post-operation, it had a sensitivity of 66.7% and specificity of 82.6%, AUC was 0.766 (P < 0.05). Pre-operative OSUI is a dependent risk factor of de novo SUI for advanced POP patients. Aa and Ba points are correlated with preoperative OSUI, and it is worthy to be

Thermoelectric transport properties of BaBiTe{sub 3}-based materials

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yiming; Zhao, Li-Dong, E-mail: zhaolidong@buaa.edu.cn

2017-05-15

BaBiTe{sub 3}, a material with low thermal conductivity, is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. We choose two types of dopants, K and La, trying to optimize its electrical transport properties. The minority carriers, which harm the Seebeck coefficient in this system, are suppressed by La doping. With the increase of both electrical conductivity and Seebeck coefficient, the power factor of 3% La doped BaBiTe{sub 3} reaches 3.7 μW cm{sup −1} K{sup −2} which increased by 40% from undoped BaBiTe{sub 3}. Besides high power factor, the thermal conductivity is also reduced in it. Eventually, a high ZT value, 0.25 at 473 K, for n-type BaBiTe{sub 3} is achieved in 3% La doped BaBiTe{sub 3}. - Graphical abstract: BaBiTe{sub 3} possesses a low thermal conductivity. However, it is an inferior thermoelectric material due to the poor electrical properties originated from its narrow band gap. A high ZT value of 0.25 at 473 K for n-type BaBiTe{sub 3} can be achieved through optimizing electrical transport properties via La doping. - Highlights: • BaBiTe{sub 3} is an analogue of these promising thermoelectric materials: such as CsBi{sub 4}Te{sub 6} and K{sub 2}Bi{sub 8}Se{sub 13}, etc. • BaBiTe{sub 3} possesses a low thermal conductivity. • La is an effective dopant to enhance electrical transport properties. • A high ZT value of 0.25 at 473 K can be achieved in n-type La-doped BaBiTe{sub 3}.

Bound-bound transitions in the emission spectra of Ba+-He excimer

Science.gov (United States)

Moroshkin, P.; Kono, K.

2016-05-01

We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6 2P3 /2 and 5 2D3 /2 ,5 /2 states of Ba+. The resulting Ba+(5 2DJ) He is a metastable electronically excited complex with orbital angular momentum L =2 , thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

Er3+ infrared fluorescence affected by spatial distribution synchronicity of Ba2+ and Er3+ in Er3+-doped BaO–SiO2 glasses

Directory of Open Access Journals (Sweden)

Atsunobu Masuno

2016-02-01

Full Text Available Glasses with the composition xBaO–(99.9 − xSiO2–0.1ErO3/2 (0 ≤x ≤ 34.9 were fabricated by a levitation technique. The glasses in the immiscibility region were opaque due to chemical inhomogeneity, while the other glasses were colorless and transparent. The scanning electron microscope observations and electron probe microanalysis scan profiles revealed that more Er3+ ions were preferentially distributed in the regions where more Ba2+ ions existed in the chemically inhomogeneous glasses. The synchronicity of the spatial distributions of the two ions initially increased with increasing x and then decreased when the Ba2+ concentration exceeded a certain value. The peak shape and lifetime of the fluorescence at 1.55 μm depended on x as well as the spatial distribution of both ions. These results indicate that although ErOn polyhedra are preferentially coordinated with Ba2+ ions and their local structure is affected by the coordination of Ba2+, there is a maximum in the amount of Ba2+ ions that can coordinate ErOn polyhedra since the available space for Ba2+ ions is limited. These findings provide us with efficient ways to design the chemical composition of glasses with superior Er3+ fluorescence properties for optical communication network systems.

Charge transfer rates for xenon Rydberg atoms at metal and semiconductor surfaces

Energy Technology Data Exchange (ETDEWEB)

Dunning, F.B. [Department of Physics and Astronomy, Rice University, MS 61, 6100 Main Street, Houston, TX 77005-1892 (United States)]. E-mail: fbd@rice.edu; Wethekam, S. [Institut fuer Physik der Humboldt-Universitaet zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Dunham, H.R. [Department of Physics and Astronomy, Rice University, MS 61, 6100 Main Street, Houston, TX 77005-1892 (United States); Lancaster, J.C. [Department of Physics and Astronomy, Rice University, MS 61, 6100 Main Street, Houston, TX 77005-1892 (United States)

2007-05-15

Recent progress in the study of charge exchange between xenon Rydberg atoms and surfaces is reviewed. Experiments using Au(1 1 1) surfaces show that under appropriate conditions each incident atom can be detected as an ion. The ionization dynamics, however, are strongly influenced by the perturbations in the energies and structure of the atomic states that occur as the ion collection field is applied and as the atom approaches the surface. These lead to avoided crossings between different atomic levels causing the atom to successively assume the character of a number of different states and lose much of its initial identity. The effects of this mixing are discussed. Efficient surface ionization is also observed at Si(1 0 0) surfaces although the ion signal is influenced by stray fields present at the surface.