| 1. |
- Ylmén, Rikard E, 1982, et al.
(författare)
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DR-FTIR method for the study of early hydration of cement
- 2008
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Ingår i: Conference Proceedings for “SCC 2008: Challenges and Barriers to Application.
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Konferensbidrag (refereegranskat)abstract
- A method has been developed to study early hydration reactions of ordinary Portland cement using freeze drying and Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DR-FTIR). The hydration process was studied after 3 minutes up to 2 hours. The cement samples were mixed and after different hydration times the samples were placed in frozen liquid hydrogen to stop the hydration process. The samples were freeze dried under vacuum and analyzed with DR-FTIR. Measurements were also made on cement that was only dried in vacuum. The results showed that the freezing of the cement instantly stopped without any further hydration. This makes it possible to monitor chemical changes during very early hydration stages of cement by using the freeze drying combined with DR-FTIR. It was also possible to dry the samples with only vacuum, but then it was not possible to study the hydration process on a short timescale. Comparison between frozen and non-frozen samples showed that the freezing do not cause any detectable differences. This clearly indicates that the freezing do not change the chemical or physical structure of the samples to any larger extent. The freezing of the samples gave a much better time resolution and made it easier to handle the samples technically as they could be stored in the liquid nitrogen and put in the freeze drier together. The vacuum dried samples on the other hand had to be put in the drier at specified times. After a sample is put in the drier, vacuum has to be established and the sample must be sufficiently dry for the hydration to stop. This limits the time resolution of the vacuum technique in this study at best to a few minutes. The limiting time step of the freezing technique is the time for freezing the samples, which in this study was a few seconds.
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| 2. |
- Ahmed, Istaq, 1972, et al.
(författare)
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Crystal structure and proton conductivity of BaZr0.9Sc0
- 2008
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Ingår i: Journal of the American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 91:9, s. 3039-3044
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Tidskriftsartikel (refereegranskat)abstract
- Solid-state sintering has been used to prepare the perovskite BaZr0.9Sc0.1O3-delta. Analysis of X-ray powder diffraction data shows that an increase of the unit cell parameter, a, was observed after deuteration. Rietveld analysis of room-temperature neutron powder diffraction data confirmed cubic symmetry (space group Pm-3m). Dynamic thermogravimetric analysis indicates that the hydration process occurs below 335 degrees C and approximately 58% of the theoretical number of protonic defects can be filled. The presence of protons/deutrons is seen from the strong O-H/O-D stretch band in the infrared spectrum of the hydrated/deuterated samples. The proton conductivity of a prehydrated sample was investigated under dry and wet Ar atmospheres
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| 3. |
- Aksouh, F., et al.
(författare)
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STUDY OF THE O-15(2p,gamma)Ne-17 CROSS SECTION BY COULOMB DISSOCIATION OF Ne-17 FOR THE rp PROCESS OF NUCLEOSYNTHESIS
- 2014
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Ingår i: Acta Physica Polonica, Series B.. - 1509-5770 .- 0587-4254. ; 45:2, s. 229-234
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Tidskriftsartikel (refereegranskat)abstract
- The O-15(2p, gamma)Ne-17 cross section has been studied by the inverse reaction, the Coulomb dissociation of Ne-17. The experiment has been performed at the GSI. The Ne-17 excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb dissociation cross sections (sigma(Coul)) have been extracted, which provide a photoabsorption (sigma(photo)) and a radiative capture cross section (sigma(cap)). Additionally, important information about the Ne-17 nuclear structure will be obtained. The analysis is in progress.
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| 4. |
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| 5. |
- Berland, Kristian, 1983, et al.
(författare)
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Temperature stability of intersubband transitions in AlN/GaN quantum wells
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:4, s. 043507-
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Tidskriftsartikel (refereegranskat)abstract
- Temperature dependence of intersubband transitions in AlN/GaN multiple quantum wells grown with molecular beam epitaxy is investigated both by absorption studies at different temperatures and modeling of conduction-band electrons. For the absorption study, the sample is heated in increments up to 400 degrees C. The self-consistent Schroumldinger-Poisson modeling includes temperature effects of the band gap and the influence of thermal expansion on the piezoelectric field. We find that the intersubband absorption energy decreases only by similar to 6 meV at 400 degrees C relative to its room temperature value.
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| 6. |
- Ekberg, Christian, 1967, et al.
(författare)
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The structure of plutonium(IV) oxide as hydrolysed clusters in aqueous suspensions
- 2013
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 42:6, s. 2035-2040
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of plutonium still puzzles scientists 70 years after its discovery. There are several factors making the chemistry of plutonium interesting including its ability to keep several oxidation states. Another unique property is that the oxidation states +III, +IV, +V and +VI may exist simultaneously in solution. Another property plutonium shares with some other tetravalent metal ions is the ability to form stable polynuclear complexes or colloids. The structures of freshly prepared and five-year old plutonium(IV) colloids are compared with crystalline plutonium(IV) oxide using Pu L-3-edge EXAFS. It was shown that as the plutonium colloids age they do in fact shrink in size, contrary to previous expectations. The aged colloidal particles are indeed very small with only 3-4 plutonium atoms, and with a structure very similar to solid plutonium(IV) oxide, but with somewhat shorter mean Pu-O bond and Pu. Pu distances indicating a partial oxidation. The very small size of the colloidal particles is further supported by the fact that they do not sediment on heavy ultra-centrifugation.
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| 7. |
- Langer, C., et al.
(författare)
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Thermonuclear reaction S-30(p,gamma)Cl-31 studied via Coulomb breakup of Cl-31
- 2014
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 89:3
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Tidskriftsartikel (refereegranskat)abstract
- Coulomb breakup at high energy in inverse kinematics of proton-rich Cl-31 was used to constrain the thermonuclear S-30(p,gamma)Cl-31 capture reaction rate under typical Type I x-ray burst conditions. This reaction is a bottleneck during rapid proton-capture nucleosynthesis (rp process), where its rate depends predominantly on the nuclear structure of Cl-31. Two low-lying states just above the proton-separation threshold of S-p = 296( 50) keV in Cl-31 have been identified experimentally using the (RB)-B-3-LAND setup at the GSI Helmholtzzentrum fur Schwerionenforschung GmbH. Both states are considered to play a key role in the thermonuclear S-30( p,gamma)Cl-31 capture reaction. Excitation energies of the first J(pi) = 1/2(+), 5/2(+) states have been extracted and the reaction rate for proton capture on S-30 under typical rp-process temperatures has been investigated.
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| 8. |
- Larsson, Kristian, 1982
(författare)
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Characterization and Dissolution of HEV NiMH Batteries
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The recycling of batteries is an important issue in a sustainable society where materials recycling of complex products is a necessity. Without an efficient recycling there will be an unnecessary loss of both materials and energy due to inefficient or non-existent recycling. This project concerns the recycling of nickel metal hydride (NiMH) hybrid electric vehicle (HEV) batteries and aims to outline the potentials and possibilities inherent in this waste stream. The main valuable metals in the batteries are nickel, cobalt and lanthanoids. The active cathode material is a triprecipitate of mainly nickel with zinc and cobalt in hydroxide form with yttrium and magnesium added,pasted onto a nickel metal foam-mesh support. The active anode material is a hydrogen absorbing alloy containing approximately 54% nickel and 31% lanthanoids and smaller amounts of manganese, cobalt, aluminium and yttrium. The recovery of these metals should be performed using a method which minimizes the use of energy and chemicals. The work presented in this thesis is a characterization of the batteries and a dissolution study of individual electrode materials as a first step in a hydrometallurgical recycling process. A nickel removal and purification process has also been investigated, the so called Mond process, by which nickel reacts with carbon monoxide and forms nickel tetracarbonyl. The nickel tetracarbonyl both forms and is highly volatile at a low temperature, unlike other relevant carbonyl compounds. This means that the volatilized nickel can easily be separated from the rest of the material and thereby purified. This gives both pure nickel and an interesting residue to work with.The positive electrode active material, nickel hydroxide, can be dissolved without dissolving the electrode backing material (nickel metal). A rapid dissolution of the active material on the positive electrode can be achieved at low temperature and relatively low acid concentration (pH 0.5-1.5), while leaving the major part of the nickel metal undissolved. This is possible with all the acids tested, nitric, sulphuric and hydrochloric acid. Therefore the most suitable acid depends on the choice of process following the dissolution.
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| 9. |
- Larsson, Kristian, 1982, et al.
(författare)
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Characterization and dissolution of hybrid electric vehicle (HEV) NIMH batteries for the development of a hydrometallurgical recycling method
- 2008
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Ingår i: Proceedings of ISEC 2008, Tucson, Arizona, US, Sept. 15-19, 2008, Vol 1 189-194. - 1894475801
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Konferensbidrag (refereegranskat)abstract
- This paper deals with a study of the chemistry behind and the development of a hydrometallurgical method specifically targeted to recycle Hybrid Electric Vehicle (HEV) type NiMH batteries. The batteries are characterized through ICP-OES, SEM and XRD to determine phases and metal content. Different dissolution techniques are utilized and their respective effect on the subsequent solvent extraction process is discussed. Thus the selection of dissolution method is closely linked to the extraction and the selective stripping of the metals.
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| 10. |
- Larsson, Kristian, 1982, et al.
(författare)
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Dissolution and characterization of HEV NiMH batteries
- 2013
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 33:3, s. 689-698
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Tidskriftsartikel (refereegranskat)abstract
- Metal recovery is an essential part of the recycling of hybrid electric vehicle battery waste and the first step in a hydrometallurgical treatment is dissolution of the solid material. The properties of separated battery electrode materials were investigated. Focus was put on both the solid waste and then the dissolution behaviour. The cathode contains metallic nickel that remains undissolved when utilizing non-oxidizing conditions such as hydrochloric or sulphuric acid in combination with a low oxygen atmosphere. In these conditions the cathode active electrode material is fully dissolved. Not dissolving the nickel metal saves up to 37% of the acid consumption for the cathode electrode material. In the commonly used case of oxidizing conditions the nickel metal dissolves and a cobalt-rich phase remains undissolved from the cathode active material. For the anode material a complete and rapid dissolution can be achieved at mild conditions with hydrochloric, nitric or sulphuric acid. Optimal parameters for all cases of dissolution was pH 1 with a reaction time of approximately >= 20,000 s.
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