| 1. |
- Akram, Nadeem, 1980-, et al.
(författare)
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Transmission of highly charged ions through phlogopite-mica nanocapillaries of rectangular cross-section
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Ingår i: Journal of Physics B. - 0953-4075 .- 1361-6455.
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Tidskriftsartikel (refereegranskat)abstract
- We measured the transmission of Ne7+ ions through nanocapillaries of rectangular cross-section produced by chemical etching of ion tracks in phlogopite mica. The two dimensional transmitted profiles are rhombic for tilt angles within the geometrical opening angle given by the aspect ratio of the short side of the rectangular cross section of the capillaries. The transmission depends on the incident charge indicating that the rhombic shape is due to the image charge of uncharged rectangular capillaries. Above a critical charge deposition, the rhombic shape tends to be smeared out. Ions are also transmitted at angles larger than the geometrical opening angle giving evidence for the guiding effect.
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| 2. |
- Björck, Matts, et al.
(författare)
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The asymmetric interface structure of bcc Fe82Ni18/Co superlattices as revealed by neutron diffraction
- 2007
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 515:08-jul, s. 3619-3623
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Tidskriftsartikel (refereegranskat)abstract
- The interface structure of Fe82Ni18/Co (001) Superlattices has been studied with a combination of X-ray and neutron diffraction. The analysis 'reveals highly asymmetric interfaces with total interface widths of 10 +/- 1 ML(monolayers) for Fe82Ni18 on Co and a maximum interface width of 1 ML for Co on Fe82Ni18. In addition it is concluded that there is no detectable long range B2-type chemical order occurring in the interface region. These results are also discussed in the context of previously measured magnetic mornents of the same system.
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| 3. |
- Brucas, R., et al.
(författare)
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Magnetization and domain structure of bcc Fe81Ni19/Co (001) superlattices
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:6, s. 064411/1-064411/11
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Tidskriftsartikel (refereegranskat)abstract
- Dense stripe domains were obsd. for a Fe81Ni19/Co superlattice grown on a MgO(100) single crystal substrate using dc magnetron sputtering. The stripe domain period exhibits irreversible changes with the magnetic field, as detd. by magnetic force microscopy. We present a simple theor. model for this system and calc. the magnetization and domain period as functions of the applied field by minimizing the total energy. For this purpose, an expression for the domain wall energy and wall width for arbitrary angles and one for the magnetostatic energy are derived. The model correctly predicts a decreasing domain period with the increasing applied field. At larger magnetic fields a transition to "chaotic" two-dimensional stripe patterns is obsd. and a qual. discussion of this phenomenon is given.
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| 4. |
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| 5. |
- Butorin, S. M., et al.
(författare)
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Resonant inelastic soft X-ray scattering studies of U(VI) reduction on iron surfaces
- 2004
-
Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807:Scientific Basis for Nuclear Waste Management XXVII, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on the spectroscopic anal. of several samples relevant to the processes governing the behavior of oxidized U species in groundwater solns. under anoxic conditions. Both Fe samples with different times of exposure to the U(IV) soln. and Fe metal-soln. interfaces in the liq. cell ex-situ and in-situ, resp. Resonant inelastic soft x-ray scattering is sensitive to the chem. state of U. The measurements were performed at a no. of energies of the primary photon beam across the U 5d absorption edge. The results unambiguously indicate the redn. of U(VI) to U(IV) on the Fe surface. [on SciFinder(R)]
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| 6. |
- Dispenza, Clelia, et al.
(författare)
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Radiation-Engineered Functional Nanoparticles in Aqueous Systems
- 2015
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 15:5, s. 3445-3467
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Forskningsöversikt (refereegranskat)abstract
- Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic routes, most manufacturing techniques are complex and only suitable for one type of particle. Interestingly, radiation chemistry, i.e., the use of ionizing radiation from radioisotopes and accelerators to induce nanomaterials or chemical changes in materials, has proven to be a versatile tool for controlled manufacturing of both organic and inorganic nanoparticles. The advantages of using radiation chemistry for this purpose are many, such as low energy consumption, minimal use of potentially harmful chemicals and simple production schemes. For medical applications one more advantage is that the material can be sterile as manufactured. Radiation-induced synthesis can be carried out in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. The radiation chemistry of water is well known, as are the various ways of fine-tuning the reactivity of the system towards a desired target by adding different solutes. This, in combination with the controllable and adjustable irradiation process parameters, makes the technique superior to most other chemical methods. In this review, we discuss the fundamentals of radiation chemistry and radiation-induced synthesis of nanoparticles in aqueous solutions. The impact of dose and dose rate as well as of controlled addition of various solutes on the final particle composition, size and size distribution are described in detail and discussed in terms of reaction mechanism and kinetics.
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| 7. |
- Haferman, H., et al.
(författare)
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Competing anisotropies in bcc Fe81Ni19/Co(001) superlattices
- 2009
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:7, s. 073102-073102-3
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Tidskriftsartikel (refereegranskat)abstract
- Amagnetization reorientation transition has been observed in Fe81Ni19/Co(001) superlattices bymeans of magneto-optical Kerr effect and magnetic force microscopy measurements.The transition is driven by the variation of the interfacedensity. First-principles calculations are combined with a linear stability analysisof the Landau–Lifshitz equation to clarify the mechanism that drivesthe transition. We are able to identify it as beingdriven by competing interface in-plane and uniaxial bulk out-of-plane anisotropies.The origin of the bulk anisotropy is attributed to tetragonaldistortions experimentally observed in these superlattices.
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| 8. |
- Häggström, Lennart, et al.
(författare)
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Thickness dependent crystallographic transition in Fe/Ni multilayers
- 2010
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 217, s. 012112-
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Tidskriftsartikel (refereegranskat)abstract
- The crystallog. transition between bcc- and fcc-structures has been studied in Fe/Ni multilayers with Moessbauer spectroscopy and X-ray diffraction. Layered structures have been confirmed and the structures depends both on individual layer thickness and the ratio of the constituents. Two sets of samples are made: the Fe layer thickness kept const. to 12 monolayer (ML) and 24ML, while the Ni layer thicknesses varied from 3 to 12ML. When the Ni layer is thin, the Fe/Ni multilayers have the bcc phase. When the thickness of Ni layer reaches 6ML and larger, a gradual transition to the fcc phase occurs. Moessbauer spectroscopy studies confirm the existence of a magnetic Fe bcc phase with in-plane magnetization in all samples, two magnetic fcc phases with fields of 28 T and 10 T and small amts. of nonmagnetic fcc phases in the thicker films. The obsd. behavior can be attributed to the existence of two types of interfaces which are not necessary overlapping each other: An elemental interface between Fe and Ni and a structural interface between fcc and bcc phases. [on SciFinder(R)]
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| 9. |
- Korzhavyi, Pavel A., 1966-, et al.
(författare)
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Exploring monovalent copper compounds with oxygen and hydrogen
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:3, s. 686-689
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Tidskriftsartikel (refereegranskat)abstract
- New important applications of copper metal, e.g., in the areas of hydrogen production, fuel cell operation, and spent nuclear fuel disposal, require accurate knowledge of the physical and chemical properties of stable and metastable copper compounds. Among the copper(I) compounds with oxygen and hydrogen, cuprous oxide Cu(2)O is the only one stable and the best studied. Other such compounds are less known (CuH) or totally unknown (CuOH) due to their instability relative to the oxide. Here we combine quantum-mechanical calculations with experimental studies to search for possible compounds of monovalent copper. Cuprous hydride (CuH) and cuprous hydroxide (CuOH) are proved to exist in solid form. We establish the chemical and physical properties of these compounds, thereby filling the existing gaps in our understanding of hydrogen- and oxygen-related phenomena in Cu metal.
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| 10. |
- Korzhavyi, Pavel A., 1966-, et al.
(författare)
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Thermodynamics of stable and metastable Cu-O-H compounds
- 2011
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Konferensbidrag (refereegranskat)abstract
- We apply density functional perturbation theory together with experimental studies in order to investigate the structure and physical properties of possible stable and metastable copper(I) compounds with oxygen and hydrogen. Copper(I) hydride, CuH, is found to be a metastable phase which decomposes at ambient conditions and exhibiting a semiconducting gap in the electronic spectrum. The calculated structure and phonon spectra are found to be in good agreement with experimental data. The phonon spectra of a novel metastable phase, copper(I) hydroxide, are also determined.
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| 11. |
- Kvashnina, Kristina, et al.
(författare)
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Changes in electronic structure of copper films in aqueous solutions
- 2007
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 19:22, s. 226002-
-
Tidskriftsartikel (refereegranskat)abstract
- The possibilities for using x-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS) to probe the Cu oxidation state and changes in the electronic structure during interaction between copper and ground-water solutions were examined. Surface modifications induced by chemical reactions of oxidized 100 Å Cu films with Cl−, SO42− and HCO3− ions in aqueous solutions with various concentrations were studied in situ using liquid cells. Copper corrosion processes in ground water were monitored for up to nine days. By comparing Cu 2p–3d, 4s transitions for a number of reference substances previously measured, changes in electronic structure of the Cu films were analysed. The XAS and RIXS spectral shape at the Cu edge, the chemical shift of the main line for Cu2+, and the energy positions of the observed satellites served as a tool for monitoring the changes during the reaction. It was found that the pH value and the Cl− concentration in solutions strongly affect the speed of the corrosion reaction.
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| 12. |
- Kvashnina, Kristina O., et al.
(författare)
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In situ X-ray absorption study of copper films in ground water solutions
- 2007
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 447:1-3, s. 54-57
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Tidskriftsartikel (refereegranskat)abstract
- This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl− and in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM prevented or slowed down the corrosion processes.
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| 13. |
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| 14. |
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| 15. |
- Li, Yunguo, et al.
(författare)
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Bond Network Topology and Antiferroelectric Order in Cuprice CuOH
- 2015
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 54:18, s. 8969-8977
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Tidskriftsartikel (refereegranskat)abstract
- Using density functional theory (DFT) and a graph theory based approach, we investigated the topology of bond network in CuOH(s) (cuprice) considering only symmetry-distinct structures. In parallel, we conducted the synthesis and X-ray diffraction characterization of the compound and used the combined theoretical-experimental effort to validate the lowest energy structure obtained with DFT. The ground-state structure of CuOH(s) consists of compact trilayers of CuOH connected to each other via hydrogen bonds, where the inner layer of each trilayer is composed entirely of Cu atoms. Each trilayer is a dense fabric made of two interlocked arrays of polymer [CuOH]n chains. This structure corresponds to an antiferroelectric configuration where the dipole moments of CuOH molecules belonging to adjacent arrays are antiparallel and are arranged in the same way as the water molecules in ice-VIII. It is shown that a collective electrostatic interaction is the main driving force for the cation ordering while the local atomic configuration is maintained. These findings and the possibility of synthesizing exfoliated two-dimensional cuprice are important for some technological applications.
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| 16. |
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| 17. |
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| 18. |
- Li, Zhuofeng, et al.
(författare)
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Inorganic/organic hybrid nanoparticles synthesized in a two-step radiation-driven process
- 2022
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Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X .- 1879-0895. ; 197, s. 110166-
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, we have synthesized inorganic-organic hybrid nanoparticles via radiation synthesis of inorganic nanoparticles (Ag and CeO2) in aqueous dispersions containing radiation-synthesized poly(N-vinyl pyrrolidone) (PVP) nanogels (NG). The experiments show that there are strong interactions between the inorganic precursors (Ag+ and Ce3+) and the nanogel prior to irradiation. The two hybrid systems (Ag/NG and CeO2/NG) were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD confirms the formation of crystalline Ag and CeO2. TEM reveals that the inorganic nanoparticles are evenly distributed in/on the nanogel. Both XRD and TEM show that size of the inorganic particles is controlled by the nanogel.
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| 19. |
- Li, Zhuofeng, et al.
(författare)
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Radiation Chemistry Provides Nanoscopic Insights into the Role of Intermediate Phases in CeO2 Mesocrystal Formation
- 2022
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 61:6
-
Tidskriftsartikel (refereegranskat)abstract
- The role of intermediate phases in CeO2 mesocrystal formation from aqueous CeIII solutions subjected to γ-radiation was studied. Radiolytically formed hydroxyl radicals convert soluble CeIII into less soluble CeIV. Transmission electron microscopy (TEM) and X-ray diffraction studies of samples from different stages of the process allowed the identification of several stages in CeO2 mesocrystal evolution following the oxidation to CeIV: (1) formation of hydrated CeIV hydroxides, serving as intermediates in the liquid-to-solid phase transformation; (2) CeO2 primary particle growth inside the intermediate phase; (3) alignment of the primary particles into “pre-mesocrystals” and subsequently to mesocrystals, guided by confinement of the amorphous intermediate phase and accompanied by the formation of “mineral bridges”. Further alignment of the obtained mesocrystals into supracrystals occurs upon slow drying, making it possible to form complex hierarchical architectures.
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| 20. |
- Li, Zhuofeng, 1991-, et al.
(författare)
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Tuning morphology, composition and oxygen reduction reaction (ORR) catalytic performance of manganese oxide particles fabricated by γ-radiation induced synthesis
- 2021
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 583, s. 71-79
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Tidskriftsartikel (refereegranskat)abstract
- A γ-radiation induced synthesis method is used to fabricate manganese oxide catalysts through both reduction and oxidation routes. It is shown that the morphology, composition and electrochemical performance of the produced manganese oxide particles can be tuned by altering the redox conditions. The catalysts prepared via radiolytic oxidation have a hollow spherical morphology, possess γ-MnO2 structure and show high catalytic activity for the complete four-electron reaction pathway of the oxygen reduction reaction (ORR) in alkaline electrolyte. Meanwhile, the catalysts synthesized via radiolytic reduction possess a rod-like morphology with a Mn3O4 bulk structure and favour the incomplete two-electron reaction pathway for ORR. The high catalytic activity of the manganese oxide synthesized via the oxidation route can be attributed to high electrochemical surface area and increased amount of Mn3+ on the surface as compared to those in the sample obtained via the reduction route.
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| 21. |
- Lousada, Claudio Miguel, et al.
(författare)
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Gamma radiation induces hydrogen absorption by copper in water
- 2016
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.
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| 22. |
- Lousada, Cláudio M., et al.
(författare)
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Synthesis of copper hydride (CuH) from CuCO3·Cu(OH)2 – a path to electrically conductive thin films of Cu
- 2017
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 46:20, s. 6533-6543
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Tidskriftsartikel (refereegranskat)abstract
- The most common synthesis methods for copper hydride (CuH) employ hard ligands that lead to the formation of considerable amounts of metallic Cu as side-product. Here we explore a synthesis method for CuH(s) through the reaction of CuCO3 center dot Cu(OH)(2)(s) with hypophosphorous acid (H3PO2) in solution, via the formation of the intermediate Cu(H2PO2)(2)(aq) complex. The reaction products were characterized with XRD, FTIR and SEM at different reaction times, and the kinetics of the transformation of Cu(H2PO2)(2)(aq) to CuH(s) were followed with NMR and are discussed. We show that our synthesis method provides a simple way for obtaining large amounts of CuH(s) even when the synthesis is performed in air. Compared to the classic Wurtz method, where CuSO4 is used as an initial source of Cu2+, our synthesis produces CuH particles with less metallic Cu side-product. We attribute this to the fact that our reaction medium is free from the hard SO42- ligand that can disproportionate Cu(I). We discuss a mechanism for the reaction based on the known reactivity of the reagents and intermediates involved. We explored the possibility of using CuH(s) for making electrically conductive films. Tests that employed water-dispersed CuH particles show that this compound can be reduced with H3PO2 leading to electrically conductive thin films of Cu. These films were made on regular office paper and were found to be Ohmic conductors even after several weeks of exposure to ambient conditions. The fact that the synthesis reported here produces large amounts of CuH particles in aqueous media, with very little impurities, and the fact that these can then be converted to a stable electrically conductive film can open up new applications for CuH such as for printing electrically conductive films or manufacturing surface coatings.
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| 23. |
- Schuch, Reinhold, et al.
(författare)
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Guiding of highly charged ions through insulating nanocapillaries
- 2008
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Ingår i: Canadian journal of physics (Print). - 0008-4204 .- 1208-6045. ; 86:1, s. 327-330
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Tidskriftsartikel (refereegranskat)abstract
- The guiding of highly charged ions through nanocapillaries in different insulating materials, such as polyethylene terephthalate, SiO2, and Al2O3 has been investigated by our group, using 7 keV Ne7+ ions. We find transmission of ions incident at angles larger than the angle given by the capillary aspect ratio in all these materials. The measured angular distributions, however, vary with the membrane material. In this report we compare the experimental findings with the different membranes.
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| 24. |
- Skog, P., et al.
(författare)
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Guiding of highly charged ions through Al2O3 nano-capillaries
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 258:1, s. 145-149
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Tidskriftsartikel (refereegranskat)abstract
- Over the past years, our group has performed experiments on ion guiding in nano-capillary membranes of polyethylene terephthalate (PET), SiO2 and Al2O3. In this paper we report the results from our recent experiments on guiding of 7 keV Ne7+-ions in Al2O3 nano-capillaries of about 1/200 aspect ratio. We will compare these experimental findings with previously obtained and published results of different membrane materials.
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| 25. |
- Skog, P., et al.
(författare)
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Guiding of slow Ne7+-ions through insulating nano-capillaries of various geometrical cross-sections
- 2009
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 194
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied guiding of slow highly charged ions through PET, SiO2, Al2O3, and now, for the first time, insulating nano-capillaries of non-circular cross-section. The guiding effect is been explained by self-organized formation of charge patches on the inner capillary walls. We investigate the effects of the geometrical cross-section on the distribution of Ne7+-ions transmitted through nano-capillaries of rhombic cross-section in muscovite mica, using ion beams of different kinetic energies. [on SciFinder(R)]
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| 26. |
- Soroka, Inna, et al.
(författare)
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Element-specific magnetic moments in bcc Fe81Ni19/Co superlattices
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:13, s. 134409-
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic moments in bcc Fe81Ni19/Co(001) superlattices with the individual layer thickness of 2-6 monolayers were studied by means of soft x-ray magnetic circular dichroism. It was found that the magnetic moment was enhanced in the Fe81Ni19 layer by about 0.35 mu(B)/atom as compared to the bulk value, while the Co moment remained unaffected by the presence of interfaces. The extension of the region with the high Fe81Ni19 moment in our samples was found to be at least 3 monolayers from the interfaces. Possible sources of the Fe81Ni19 moment enhancement were considered in ab initio calculations, and it was concluded that the enhanced moment may be explained by intermixing and formation of a B2-type short-range order at the interfaces.
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| 27. |
- Soroka, Inna, et al.
(författare)
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Enhanced magnetic moment at the interfaces in Fe81Ni19/Co superlattices
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 277:1-2, s. 228-235
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Tidskriftsartikel (refereegranskat)abstract
- The structure and magnetic properties of BCC (0 0 1) oriented Fe81Ni19/Co superlattices grown on MgO(0 0 1) substrates by magnetron sputtering are presented. The variation of magnetic moment with the compn. and with the interface d. was studied. A model in which the magnetic moment per atom at the interfaces is different from that in the interior region was used for the anal. The extension of the interface region is ∌3.5 monolayers and the magnetic moment in this region is enhanced by ∌0.3 ΌB/atom, compared to the interior regions. The superlattices form a BCC-like structure with a slight orthorhombic distortion, which gives rise to a weak in-plane uniaxial anisotropy. [on SciFinder(R)]
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| 28. |
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| 29. |
- Soroka, Inna L., et al.
(författare)
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Cuprous hydroxide in a solid form : does it exist?
- 2013
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Ingår i: Dalton Transactions. - : RSC Publishing. - 1477-9226 .- 1477-9234. ; 42:26, s. 9585-9594
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Tidskriftsartikel (refereegranskat)abstract
- Experimental studies have been performed to obtain the unknown cuprous hydroxide compound, which has recently been predicted theoretically (P. A. Korzhavyi et. al., Proc. Natl. Acad. Sci. U. S. A., 2012, 109, 686-689) to be metastable in a solid form. The reduction of Cu2+ with ferrous ethylenediamine tetraacetate (EDTA) results in the formation of a yellow powder precipitate whose composition corresponds to CuOH x H2O as probed by Fourier Transform Infrared Spectroscopy (FTIR) and cryogenic X-ray Photoelectron Spectroscopy (XPS). A similar compound has been found on the surface of Cu-CuH powder stored in water, as detected by XPS. The reduction of Cu2+ to Cu+ with free radicals in aqueous solutions results in a Cu2O precipitate as the final product, while the formation of the yellow cuprous hydroxide colloids may be an intermediate step. Our studies reveal that cuprous hydroxide does exist in a solid form and most likely has a hydrated form, CuOH x H2O.
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| 30. |
- Soroka, Inna L., et al.
(författare)
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Effect of synthesis temperature on the morphology and stability of copper(I) hydride nanoparticles
- 2013
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 15:42, s. 8450-8460
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Tidskriftsartikel (refereegranskat)abstract
- The effect of synthesis temperature on the morphology and stability of copper(I) hydride nanoparticles is studied. Monovalent copper hydride is obtained by reduction of Cu2+ sulfate with hypophosphorous acid at temperatures ranging from 45 degrees C to 75 degrees C. The CuH nanoparticles that formed have the shape of desert roses and are found to be very porous. The lattice parameter, size, and morphology of these nanoparticles depend on the synthesis temperature. CuH is a metastable compound. In air under ambient conditions, it first decomposes into copper metal and hydrogen gas and then the copper oxidizes. The copper particles that are left after the decomposition of copper(I) hydride in air have the same desert-rose morphology as the CuH nanoparticles. The copper particles with desert-rose shapes are observed for the first time. Copper(I) hydride decomposes slower in an aqueous environment than in air to form copper(I) oxide as the final product through formation of hydrated copper(I) hydroxide as an intermediate phase. The retarded decomposition of CuH in water may be explained by the formation of a protective CuOH center dot H2O layer on the surface of copper(I) hydride.
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| 31. |
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| 32. |
- Soroka, Inna L., et al.
(författare)
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Structural stability and oxidation resistance of amorphous Zr-Al alloys
- 2010
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 401:1-3, s. 38-45
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the structural stability and oxidation resistance of Zr-Al films upon annealing in air. The concentration of Zr was varied from 0 to 100 at.%, with a step of 10 at.%. The films were fabricated using ultra-high vacuum based magnetron sputtering. The as-deposited films with Zr content from 17.3 at.% to 70.7 at.% were found to be X-ray amorphous at room temperature. When exposed to air a thin oxide layer, typically less than 6 nm, is formed. The thickness of the oxide layers increases when the samples are annealed in air and most of these are found to be fully oxidized at 700 degrees C with the formation of crystalline and amorphous oxides on the top of crystalline and amorphous metal films, respectively. The amorphous oxide layers are found to be dense, with well defined thicknesses. An experimental non-equilibrium phase diagram is provided, covering the whole concentration range of the Zr-Al system. (C) 2010 Elsevier B.V. All rights reserved.
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| 33. |
- Soroka, Inna, 1966-
(författare)
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Magnetic Heterostructures : The Effect of Compositional Modulation on Magnetic Properties
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The effect of compositional modulation on structural and magnetic properties of magnetic heterostructures was explored. The systems under focus were ferromagnetic superlattices Fe81Ni19/Co, metal-insulator multilayers Al2O3/Ni81Fe19, nanoparticles and artificial multilayered pillars. The heterostuctures were grown by magnetron sputtering in a state-of-the-art ultra-high vacuum system. The structural characterization was done by X-ray diffraction and reflectivity, as well as by transmission electron microscopy. Magneto-optical Kerr effect, SQUID and XMCD magnetometry and magnetic force microscopy were used for magnetic characterization. The bilayer thickness, ratio of the constituents and the interface quality influence the magnetic properties (magnetic moments and anisotropy) of metallic heterostructures. In particular, magnetic moments in bcc Fe81Ni19/Co superlattices were found to scale with the interface density thus, implying different magnetic moments at the interfaces as compared to the interior part of the layers. The easy direction of magnetization can be rotated from in-plane to out-of-plane, by increasing the bilayer thicknesses, keeping other parameters unchanged. Consequently, the anisotropy strength is strongly dependent on the repeat distance. Stripe domains appear in the films that possess an out-of-plane magnetization. The average domain period was found to be dependent on the applied in-plane magnetic field and on the total thickness of the films. The structural and magnetic properties of Al2O3/Ni81Fe19 multilayers depend strongly on the individual layers thicknesses. By increasing the amount of the magnetic deposits one can change the obtained film structure, from superparamagnetic nanoparticles to ferromagnetic multilayers. By increasing the oxide layer thickness the magnetic behavior of the nanoparticles can be altered from ferromagnetic, via spin glass like, to a superparamagnetic character.
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| 34. |
- Soroka, Inna, et al.
(författare)
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Nonconvex Morphology of Metallic Copper Obtained via Nonclassical Crystallization of Copper Hydride
- 2019
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Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 19:9, s. 5275-5282
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Tidskriftsartikel (refereegranskat)abstract
- Copper particles with a desert rose morphology and high surface area were obtained via decomposition of a copper hydride whose particles possesses a similar shape. Copper hydride was synthesized by the reaction between copper sulfate and hypophosphorous acid at 50 degrees C. The different reaction steps of the copper hydride formation were monitored by two time-dependent techniques: in situ photon cross-correlation spectroscopy and ex -situ transmission electron microscopy. At the initial stage of the reaction, emulsion droplets of a particular size were formed, followed by the growth and agglomeration of copper hydride crystallites in the confinement of these droplets. The final structure consists of roselike shaped particles with an average size of about 217 +/- 53 nm arranged into chains. The surface area of these particles was estimated to be 41 +/- 8 m(2)/g. The nucleation and growth of the copper hydride occur via a nonclassical crystallization pathway.
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| 35. |
- Soroka, Inna, et al.
(författare)
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On the mechanism of gamma-radiation-induced corrosion of copper in water
- 2021
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Radiation-induced corrosion of the copper canister used to contain the spent nuclear fuel in future geological repositories is a process of potential importance for the long-term safety. In recent years, several experimental studies have been conducted to elucidate the mechanism of this process. However, experimental observations and numerical simulations based on the proposed mechanism are not in agreement. In this work we have explored the mechanism further. Based on a series of experimental observations we propose a new mechanism where the corrosion of copper is driven by radiolytically produced O-2.
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| 36. |
- Soroka, Inna, et al.
(författare)
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Origin of uniaxial in-plane magnetic anisotropy in Fe81Ni19/Co superlattices.
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 272, s. 1247-1248
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Tidskriftsartikel (refereegranskat)abstract
- The authors have studied the in-plane magnetic uniaxial anisotropy, for (0 0 1)-oriented Fe81Ni19/Co superlattices grown on MgO (0 0 1) by magnetron sputtering. The layers in the superlattices have a BCC structure with a slight orthorhombic distortion, which gives rise to a weak in-plane uniaxial anisotropy. [on SciFinder(R)]
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| 37. |
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| 38. |
- Soroka, Inna, et al.
(författare)
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Particle size effect of Ag-nanocatalysts deposited on carbon as prepared by γ-radiation induced synthesis
- 2020
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Ingår i: Radiation Physics and Chemistry. - : Elsevier. - 0969-806X .- 1879-0895. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- The effect of silver particle sizes on the catalytic performance of Ag/C electrodes for oxygen reduction reaction (ORR) was studied. The Ag particles were precipitated from AgNO3 solutions on Vulcan XC-72 carbon as support by γ-radiation induced synthesis method. The structural and morphological characterizations of the electrode materials were done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that particles with smaller diameters, 11 ± 6 nm, possess higher catalytic activity for ORR (50 mA/cm2 at 0.3 V) as compared to those with larger diameters, 41 ± 5 nm, ORR activity is 25 mA/cm2 at 0.3 V. The observed effect may be explained by an increased amount of low coordinated atoms in smaller particles as compared to the larger ones.
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| 39. |
- Soroka, Inna, et al.
(författare)
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Radiation-induced synthesis of nanoscale Co-and Ni-based electro-catalysts on carbon for the oxygen reduction reaction
- 2017
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Ingår i: Dalton Transactions. - London, Storbritannien : Royal Society of Chemistry. - 1477-9226 .- 1477-9234. ; 46:30, s. 9995-10002
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Tidskriftsartikel (refereegranskat)abstract
- A facile synthesis of 3d-metal based electro-catalysts directly incorporated into a carbon support was carried out by.-radiation. Transition metals of period 4, i.e. Ni and Co, were precipitated and reduced from their respective salt solutions. The obtained materials were characterized by XRD, SEM, SQUID and the BET methods. Thereafter, the electrodes for fuel cells were fabricated out of synthesized material and their electrochemical performance for the oxygen reduction reaction in 6 M KOH was measured. Although the concentrations of Co and Ni in the electrode material were low (3.4% Co and 0.4% Ni) after reduction by irradiation, both the Ni and Co-based gas diffusion electrodes showed high catalytic activity for oxygen reduction both at room temperature and at 60 degrees C.
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| 40. |
- Soroka, Inna, et al.
(författare)
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Structural and magnetic properties of Al2O3/Ni81Fe19 thin films : From superparamagnetic nanoparticles to ferromagnetic multilayers
- 2005
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 17:33, s. 5027-5036
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Tidskriftsartikel (refereegranskat)abstract
- Al2O3/Ni81Fe19 multilayer films were produced by sequential magnetron sputter deposition on thermally oxidized Si(001) substrates. By varying the thickness of the Ni81Fe19 layer from 8 to 30 Aa, while keeping the other parameters unchanged, one can control the film structure from nanoclusters to continuous multilayers. The nanoclustered sample is superparamagnetic while the continuous samples show ferromagnetic behavior. The magnetic moments per atom of the Ni81Fe19 layers decrease with decreasing amt. of metallic deposits, indicating the presence of nonmagnetic layers at the interfaces. The thicknesses of these layers are ∌1 Aa for the flat continuous film and 3.8 Aa for the nanoclustered film. The existence of nonmagnetic layers may be interpreted in terms of the formation of antiferromagnetic oxides at the interfaces. [on SciFinder(R)]
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| 41. |
- Soroka, Inna, et al.
(författare)
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Template-based multiwalled TiO2/iron oxides nanotubes: : Structure and magnetic properties
- 2009
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Ingår i: Journal of Applied Physics. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 106:8, s. 084313-
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Tidskriftsartikel (refereegranskat)abstract
- Double-and triple-walled TiO2/iron oxide nanotubes with well defined interfaces havebeen produced in nanoporous alumina templates using atomic layer depositionmethod. The structural properties of each individual layer are foundto be dependent on the deposition temperatures. The outer layersof TiO2 are polycrystalline and consist of a phase mixtureof anatase and rutile, while the inner TiO2 layers grownat lower temperature are amorphous. The iron oxide layers consistof pure hematite when deposited at 500 °C, while a phasemixture of hematite and magnetite was obtained at 400 °C. Themagnetization measurements reveal that the studied nanotubes exhibit weak ferromagneticbehavior and magnetic anisotropy with an easy axis perpendicular tothe tube axis.
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| 42. |
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| 43. |
- Stanciu, V., et al.
(författare)
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Dynamic magnetic properties of Ni81Fe19/Al2O3 multilayers
- 2005
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 286:SI, s. 446-449
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Tidskriftsartikel (refereegranskat)abstract
- Discontinuous magnetic metal-insulator multilayers of Ni81Fe19 and Al2O3 were prepd. by sequential magnetron sputtering in an UHV chamber. Ni81Fe19 layers of nominal thickness 8 Å form clusters of quite uniform size having an av. diam. of ∌24 Å. A layered structure is maintained in the out-of-plane direction, but a random distribution of the metal clusters occurs in plane. These films have magnetic properties that vary strongly with the Al2O3 layer thickness-exhibiting ferromagnetic, spin glass like and superparamagnetic behavior as this layer thickness is increased from 10 via 19 to 31
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| 44. |
- Van Kampen, M., et al.
(författare)
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On the realization of artificial XY spin chains
- 2005
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Ingår i: Journal of Physics. - 0953-8984 .- 1361-648X. ; 17:2, s. L27-L33
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Tidskriftsartikel (refereegranskat)abstract
- Spin chains are the most elementary entities in the study of magnetic ordering behavior. The authors describe a route toward the realization of artificial XY spin chains. Using thin-film deposition and e-beam lithog., 300 and 550 nm diam. pillars consisting of alternating disks of permalloy and Al2O3 were made. Shape anisotropy forces the magnetization in plane, creating a chain of two-dimensional magnetic moments →i. The disks couple to each other by their dipolar stray fields, resulting in an interaction Jij→i·→j, with Jij the coupling between disks i and j. This form closely resembles a chain of xy spins, coupled by effective interactions Jij. The authors present a magnetic characterization of the pillars, and compare the results with model calcns. Also, spin dynamics and ordering phenomena are addressed.
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| 45. |
- Vegelius, Johan, et al.
(författare)
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Atomic and electronic structure of amorphous Al-Zr alloy films
- 2011
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 23:26, s. 265503-
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous Al73Zr27 alloy film, grown and then subjected to heat treatments at 400 and 700 degrees C, was studied using a combination of x-ray diffraction and soft x-ray spectroscopic techniques. The Al L-2,L-3 and Al K x-ray absorption spectroscopy (XAS) and Al L-2,L-3 x-ray emission spectroscopy (XES) used allowed probing the unoccupied and occupied Al 3s, d states and unoccupied Al 3p states in the sample studied. An irreversible transition from amorphous alloy to a mixture of polycrystalline alloy and amorphous alloy, and then to an amorphous oxide phase was observed. After the annealing at 400 degrees C the Al L-2,L-3 spectra obtained by XAS could be explained as sums of spectra from amorphous Al73Zr27 alloy and (poly) crystalline Al. This indicates that the sample consists of a mixture of Al-rich crystalline and Zr-enhanced amorphous alloys, as compared to the stoichiometry of the as-deposited Al73Zr27 sample, and that the electronic wavefunctions in the crystalline and amorphous regions can be considered to be confined within the respective regions. The relative amounts of Al atoms were found to be around 1: 3 in the crystalline and amorphous phases, respectively, as deduced from the analysis of changes in the electronic structure using Al L-2,L-3 XAS data. The interpretation was confirmed by the Al K XAS and Al L-2,L-3 XES. Upon further annealing at 700 degrees C the polycrystalline phase transformed into amorphous oxide, while the amorphous alloy phase underwent gradual oxidation. The important finding was that the greater part of the sample remained in the amorphous state throughout the temperature regimes described.
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| 46. |
- Vegelius, Johan, 1981-, et al.
(författare)
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Cu Kβ2,5 X-ray emission spectroscopy as a tool for characterization of monovalent copper compounds
- 2012
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Ingår i: Journal of Analytical Atomic Spectrometry. - 0267-9477 .- 1364-5544. ; 27:11, s. 1882-1888
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Tidskriftsartikel (refereegranskat)abstract
- Cu Kβ 2,5 X-ray emission and resonant inelastic X-ray scattering measurements were performed on monovalent and divalent copper compounds. The data were compared with the results of local-density- approximation calculations. The methods were found to be efficient tools for studies of Cu 4p states in the valence band and for distinguishing between different monovalent copper compounds. This is of particular importance for the debate concerning copper corrosion in oxygen-free water.
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| 47. |
- Vegelius, J. R., et al.
(författare)
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Cu K beta(2,5) X-ray emission spectroscopy as a tool for characterization of monovalent copper compounds
- 2012
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 27:11, s. 1882-1888
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Tidskriftsartikel (refereegranskat)abstract
- Cu Kβ 2,5 X-ray emission and resonant inelastic X-ray scattering measurements were performed on monovalent and divalent copper compounds. The data were compared with the results of local-density- approximation calculations. The methods were found to be efficient tools for studies of Cu 4p states in the valence band and for distinguishing between different monovalent copper compounds. This is of particular importance for the debate concerning copper corrosion in oxygen-free water.
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| 48. |
- Vegelius, J. R., et al.
(författare)
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X-ray Spectroscopic Study of Cu2S, CuS, and Copper Films Exposed to Na2S Solutions
- 2012
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:42, s. 22293-22300
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of copper sulfides was studied using X-ray absorption at Cu K and L-2,L-3 and S L-2,L-3 edges and X-ray emission spectroscopy at S L-2,L-3 thresholds. The experimental data were compared with results of local density approximation calculations taking into account the calculated valence band contributions and core-level chemical shifts between inequivalent sites. The presence of divalent Cu was detected in CuS with X-ray absorption spectroscopy in the high-energy-resolution fluorescence detection (HERFD) mode. The S L-2,L-3 emission spectrum of CuS was found to be significantly broader than that of Cu2S due to contributions from inequivalent S sites. This difference in the spectral width was used to distinguish between sulfide species formed on the Cu foil exposed to Na2S solutions. The Cu-S interaction processes for Cu films of different thicknesses exposed to Na2S solutions were monitored in situ using X-ray absorption spectroscopy in the HERFD mode at the Cu K edge. It was found that Cu ions were diffusing in the sulfide and entering the solution. The rate at which Cu ions enter the solution via diffusion was estimated on the basis of the results for a 1000 angstrom thick film.
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| 49. |
- Wei, Zheng, et al.
(författare)
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Can gamma irradiation during radiotherapy influence the metal release process for biomedical CoCrMo and 316L alloys?
- 2018
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 106:7, s. 2673-2680
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Tidskriftsartikel (refereegranskat)abstract
- The extent of metal release from implant materials that are irradiated during radiotherapy may be influenced by irradiation-formed radicals. The influence of gamma irradiation, with a total dose of relevance for radiotherapy (e.g., for cancer treatments) on the extent of metal release from biomedical stainless steel AISI 316L and a cobalt-chromium alloy (CoCrMo) was investigated in physiological relevant solutions (phosphate buffered saline with and without 10 g/L bovine serum albumin) at pH 7.3. Directly after irradiation, the released amounts of metals were significantly higher for irradiated CoCrMo as compared to nonirradiated CoCrMo, resulting in an increased surface passivation (enhanced passive conditions) that hindered further release. A similar effect was observed for 316L showing lower nickel release after 1 h of initially irradiated samples as compared to nonirradiated samples. However, the effect of irradiation (total dose of 16.5 Gy) on metal release and surface oxide composition and thickness was generally small. Most metals were released initially (within seconds) upon immersion from CoCrMo but not from 316L. Albumin induced an increased amount of released metals from AISI 316L but not from CoCrMo. Albumin was not found to aggregate to any greater extent either upon gamma irradiation or in the presence of trace metal ions, as determined using different light scattering techniques. Further studies should elucidate the effect of repeated friction and fractionated low irradiation doses on the short- and long term metal release process of biomedical materials.
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| 50. |
- Yang, Miao, et al.
(författare)
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Exploring the limitations of the Hantzsch method used for quantification of hydroxyl radicals in systems of relevance for interfacial radiation chemistry
- 2017
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Ingår i: Radiation Physics and Chemistry. - : Elsevier. - 0969-806X .- 1879-0895. ; 130, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- In the presence of Tris or methanol, hydroxyl radicals in systems of relevance for interfacial radiation chemistry can be quantified indirectly via the Hantzsch method by determining the amount of the scavenging product formaldehyde formed. In this work, the influence of the presence of H2O2 on the Hantzsch method using acetoacetanilide (AAA) as derivatization reagent is studied. The experiments show that the measured CH2O concentration deviates from the actual concentration in the presence of H2O2 and the deviation increases with increasing [H2O2]0/[CH2O]0. The deviation is negative, i.e., the measured formaldehyde concentration is lower than the actual concentration. This leads to an underestimation of the hydroxyl radical production in systems containing significant amount of H2O2. The main reason for the deviation is found to be three coupled equilibria involving H2O2, CH2O and the derivative produced in the Hantzsch method.
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