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| 2. |
- Andersson, Jon Martin, et al.
(författare)
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Phase control of Al2O3 thin films grown at low temperatures
- 2006
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 513:1-2, s. 57-59
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Tidskriftsartikel (refereegranskat)abstract
- Low-temperature growth (500 °C) of α-Al2O3 thin films by reactive magnetron sputtering was achieved for the first time. The films were grown onto Cr2O3 nucleation layers and the effects of the total and O2 partial pressures were investigated. At 0.33 Pa total pressure and ≥ 16 mPa O2 partial pressure α-Al2O3 films formed, while at lower O2 pressure or higher total pressure (0.67 Pa), only γ phase was detected in the films (which were all stoichiometric). Based on these results we suggest that α phase formation was promoted by a high energetic bombardment of the growth surface. This implies that the phase content of Al2O3 films can be controlled by controlling the energy of the depositing species. The effect of residual H2O (10− 4 Pa) on the films was also studied, showing no change in phase content and no incorporated H (< 0.1%). Overall, these results are of fundamental importance in the further development of low-temperature Al2O3 growth processes.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Hugosson, Håkan Wilhelm, 1972-, et al.
(författare)
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Stabilization of potential superhard RuO2 phases: A theoretical study
- 2002
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 66:17
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Tidskriftsartikel (refereegranskat)abstract
- First-principles full-potential linear muffin-tin orbital calculations have been used to study RuO2 in the fluorite (CaF2) and rutile structures. An investigation of the effects of metal and nonmetal alloying, oxygen vacancies, and lattice strain on the phase stabilities and electronic structure has been made. From these theoretical results suggestions on how the cubic phase may be stabilized are made. The pressure induced phase transitions between the rutile, CaCl2, Pa3 and fluorite phases and the bulk moduli of several 4d and 5d transition metal dioxides have also been studied.
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| 7. |
- Jacobsen, SN, et al.
(författare)
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Sharp microfaceting of (001)-oriented cerium dioxide thin films and the effect of annealing on surface morphology
- 1999
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Ingår i: Surface Science. - 0039-6028. ; 429:1-3, s. 22-33
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Tidskriftsartikel (refereegranskat)abstract
- Cerium dioxide, CeO2, is a chemically stable oxygen-ion-conducting material, which has been extensively used as an additive or support in oxidation catalysts. The fact that catalytic behaviour is often surface structure sensitive and/or edge atom dependent suggests that different surfaces might be discernible in associated redox processes. Thus, it is desirable to realise CeO2 films with a well-defined microstructure and with crystallographically uniform surfaces. In this paper we present evidence of extremely sharp microfaceting on the surface of thin CeO2 films grown by r.f. magnetron sputtering, and the effect of annealing on the formed sharp ridges. The results show that nominally designated crystallographic surfaces may in fact not coincide with the surfaces exposed as-grown. Thus, there is a clear risk for erroneous interpretation of various orientation-dependent surface properties. Carefully controlled annealing of these films can be utilised as a method for tailoring the resulting surface morphology on the atomic scale.
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| 8. |
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| 10. |
- MAGNUSSON, J, et al.
(författare)
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FLUX PINNING IN YBA2CU3O7 THIN-FILMS GROWN BY DC MAGNETRON SPUTTERING
- 1992
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Ingår i: Cryogenics (Guildford). - : Elsevier BV. - 0011-2275 .- 1879-2235. ; 32, s. 1084-1088
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of YBa2Cu3O7 (YBCO) were deposited on single crystalline LaAlO3 substrates using d.c. magnetron sputtering. The quality of the films has been assessed by X-ray diffraction; YBa2Cu3O7 grows epitaxially with the c-axis parallel to the substrate normal. For some choices of the deposition parameters in the sputtering process, it was found that secondary phases were precipitated in the films. By a deliberate choice of deposition parameters, semi-coherently grown Y2O3 (yttria) inclusions could be obtained. They had square platelet or cubical shapes with sizes from 5 - 20 nm and thickness approximately 10 nm. The superconducting properties of the YBa2Cu3O7 films were investigated using SQUID magnetometry. Magnetization measurements on films with different densities of semicoherent Y2O3 inclusions indicate an enhanced flux pinning capability with increasing inclusion density.
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| 11. |
- Massad, Eduardo, et al.
(författare)
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Estimating the probability of dengue virus introduction and secondary autochthonous cases in Europe
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Given the speed of air travel, diseases even with a short viremia such as dengue can be easily exported to dengue naïve areas within 24 hours. We set out to estimate the risk of dengue virus introductions via travelers into Europe and number of secondary autochthonous cases as a result of the introduction. We applied mathematical modeling to estimate the number of dengue-viremic air passengers from 16 dengue-endemic countries to 27 European countries, taking into account the incidence of dengue in the exporting countries, travel volume and the probability of being viremic at the time of travel. Our models estimate a range from zero to 167 air passengers who are dengue-viremic at the time of travel from dengue endemic countries to each of the 27 receiving countries in one year. Germany receives the highest number of imported dengue-viremic air passengers followed by France and the United Kingdom. Our findings estimate 10 autochthonous secondary asymptomatic and symptomatic dengue infections, caused by the expected 124 infected travelers who arrived in Italy in 2012. The risk of onward transmission in Europe is reassuringly low, except where Aedes aegypti is present.
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| 12. |
- Music, Denis, et al.
(författare)
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Elastic modulus-density relationship for amorphous boron suboxide thin films
- 2003
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 76:2, s. 269-271
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Tidskriftsartikel (refereegranskat)abstract
- Boron suboxide thin films nave been deposited on Si(100) substrates by reactive RF magnetron sputtering of a sintered B target in an Ar/O2 atmosphere. Elastic recoil detection analysis was applied to determine the film composition and density. Film structure was studied by X-ray diffraction and transmission electron microscopy. The elastic modulus, measured by nanoindentation, was found to decrease as the film density decreased. The relationship was affected by tuning the negative substrate bias potential and the substrate temperature during film growth. A decrease in film density, by a factor of 1.55, caused an elastic modulus reduction by a factor of 4.5, most likely due to formation of nano-pores containing Ar. It appears evident that the large scattering in the published data on elastic properties of films with identical chemical composition can readily be understood by density variations. These results are important for understanding the elastic properties of boron suboxide, but may also be qualitatively relevant for other B-based material systems.
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| 13. |
- Music, Denis, et al.
(författare)
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Elastic modulus of amorphous boron suboxide thin films studied by theoretical and experimental methods
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:2, s. 940-944
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Tidskriftsartikel (refereegranskat)abstract
- Elastic modulus of amorphous boron suboxide thin films was studied by theoretical and experimental methods. It was shown that the increase of x in the a-BOx films from 0.08 to 0.18 decreased the magnitude of the elastic modulus from 273 to 231 GPa. The decrease of the elastic modulus with an increasing amount of O was correlated to the presence of the long B-O bonds with ionic contribution and the reduction of the film density.
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| 14. |
- Music, Denis, et al.
(författare)
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Quantum design and synthesis of a boron-oxygen-yttrium phase
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:24, s. 4286-4288
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Tidskriftsartikel (refereegranskat)abstract
- A study was performed on quantum design and synthesis of a boron-oxygen-yttrium (BOY) phase. The calculations predicted that the BOY phase was 0.36 eV/atom more stable than crystalline BO0.17. The results showed that films with Y/B ratios ranging from 0.10 to 0.32, as determined via elastic recoil detection analysis, were grown over wide range of temperatures (300-600°C) and found to withstand 1000°C.
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| 15. |
- Olsson, MK, et al.
(författare)
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High rate reactive de magnetron sputter deposition of Al2O3 films
- 1998
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Ingår i: JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS. - : AMER INST PHYSICS. - 0734-2101. ; 16:2, s. 639-643
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Aluminum oxide films were produced by reactive de magnetron sputtering of Al in Ar+O-2. The composition of the films was characterized by Rutherford backscattering measurements. Stoichiometric films possessed excellent optical properties with a refractive
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| 16. |
- Rocklöv, Joacim, et al.
(författare)
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Assessing Seasonal Risks for the Introduction and Mosquito-borne Spread of Zika Virus in Europe
- 2016
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Ingår i: EBioMedicine. - : Elsevier. - 2352-3964. ; 9, s. 250-256
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Tidskriftsartikel (refereegranskat)abstract
- The explosive Zika virus epidemic in the Americas is amplifying spread of this emerging pathogen into previously unaffected regions of the world, including Europe (Gulland, 2016), where local populations are immunologically naïve. As summertime approaches in the northern hemisphere, Aedes mosquitoes in Europe may find suitable climatic conditions to acquire and subsequently transmit Zika virus from viremic travellers to local populations. While Aedes albopictus has proven to be a vector for the transmission of dengue and chikungunya viruses in Europe (Delisle et al., 2015; ECDC, n.d.) there is growing experimental and ecological evidence to suggest that it may also be competent for Zika virus(Chouin-Carneiro et al., 2016; Grard et al., 2014; Li et al., 2012; Wong et al., 2013). Here we analyze and overlay the monthly flows of airline travellers arriving into European cities from Zika affected areas across the Americas, the predicted monthly estimates of the basic reproduction number of Zika virus in areas where Aedes mosquito populations reside in Europe (Aedes aegypti in Madeira, Portugal and Ae. albopictus in continental Europe), and human populations living within areas where mosquito-borne transmission of Zika virus may be possible. We highlight specific geographic areas and timing of risk for Zika virus introduction and possible spread within Europe to inform the efficient use of human disease surveillance, vector surveillance and control, and public education resources.
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| 17. |
- Selinder, T.I., et al.
(författare)
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Structural characterization of yttria (Y2O3) inclusions in YBa2Cu3O7−x films : Growth model and effect on critical current density
- 1993
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Ingår i: Thin Solid Films. - 0040-6090. ; 229:2, s. 237-248
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Tidskriftsartikel (refereegranskat)abstract
- A higher critical current and enhanced pinning was obtained in c-axis-oriented YBa2Cu3O7−x (YBCO)films having a higher density of semicoherent yttria (Y2O3) inclusions. The films were grown by sputtering and the inclusion density depends on the fraction of N2O in the sputtering gas. The inclusions were studied by transmission electron microscopy, both in planar sections and in cross-sections. They are embedded in the YBCO matrix without disturbing its structure appreciably, and the inclusion density is up to about 1017 cm−3, comprising about 4% of the film volume. From the appearance of moiré fringes and from high resolution transmission electron micrographs, it is concluded that the inclusions are highly oriented and have coherent or semicoherent interfaces towards matrix. A model for formation of the yttria inclusions during film growth is presented, which includes nucleation of epitaxial coherent yttria islands, layer-by-layer growth and finally overgrowth by advancing steps of the YBCO film. The enhanced pinning and transport critical current densities, relation to film microstructure and the possible flux-pinning mechanisms by these yttria inclusions are discussed.
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| 18. |
- Skårman, Björn, et al.
(författare)
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Carbon monoxide oxidation on copper oxide thin films supported on corrugated cerium dioxide {111} and {001} surfaces
- 1999
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 1090-2694 .- 0021-9517. ; 181:1, s. 6-15
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of CeO2 with and without a thin layer of copper oxide were prepared by rf magnetron sputtering on surfaces of alpha-Al2O3 (sapphire) substrates. Careful characterisation of the surfaces was performed down to the atomic level using high-resolution electron-microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Surprisingly, the as-deposited, corrugated ceria surfaces, nominally (001), consist exclusively of {111}-type lattice planes, but, upon annealing at 800 degrees C, a well-defined portion of (001) surfaces are formed. Oxidation of carbon monoxide to carbon dioxide was studied, having the prepared films in a stirred batch reactor. A batch reactor was chosen so that the conversion over the small sample surface area (ca 10(-4) m(2)) could be monitored as a function of the reaction time. The activity of copper oxide on annealed ceria surfaces is markedly higher than on nonannealed surfaces, indicating a favourable synergetic effect between the ceria (001) surface and the copper oxide phase. (C) 1999 Academic Press.
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| 19. |
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| 21. |
- Wang, Z., et al.
(författare)
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Peroxo sol-gel preparation : Photochromic/electrochromic properties of Mo-Ti oxide gels and thin films
- 2000
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 10:10, s. 2396-2400
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Tidskriftsartikel (refereegranskat)abstract
- Metallic Mo powder and Ti(OBu(n))4 were separately dissolved in H2O2 solution and the solutions obtained mixed in different Mo/Ti atomic ratios to prepare precursor solutions. Fresh gels obtained from the precursor solutions with >40% Mo became blue upon exposure to ambient light. X-Ray photoelectron spectroscopy (XPS) was used to examine the chemical states and compositions of the resultant blue-tinged xerogel powders. Based on the XPS results, it is proposed that TiO2 particles and surface species, including adsorbed water and organic residue, all contribute to the photochromic effect of MoO3. Mo-Ti oxide films were spin-coated on ITO-coated glass substrates using a precursor solution containing 70% Mo. The cycling behaviours of the films annealed at 150°C for 1 h were studied using cyclic voltammetry (CV) in propylene carbonate solution containing I mol L-1 LiClO4. The electrochromic properties of the films upon lithium intercalation were investigated by in situ monochromatic transmittance measurements during the CV process, as well as ex situ in the UV/Vis region. The Mo-Ti oxide films were found to possess excellent electrochromic properties upon Li+ ion insertion/extraction.
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| 22. |
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