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  • 101.
    Kinschel, Dominik
    KTH, Skolan för kemivetenskap (CHE).
    Stable Redox Systems for Dye-Sensitized Solar Cells2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Dye sensitized solar cells are a new type of solar cells which open a new market thanks to their unique properties, which are semi transparency and the fact that they can be produced in various colors.

    After improving two existing syntheses for industrial applications, this thesis takes the approach to develop new redox mediators for devices with an aim on improving stability. Five redox mediators with cobalt, copper and iron as metal center were synthesized and characterized by NMR spectroscopy, cyclic voltammetry and UV/VIS spectrophotometry. Three of them were selected for evaluation in test cells. Most promising results were obtained with a copper complex, using the tandem redox approach a new record efficiency of 7.7% for copper based electrolytes in dye-sensitized solar cells was obtained.

  • 102.
    Kjellin, Per
    et al.
    Chalmers tekniska högskola, Göteborg.
    Ekström, Henrik
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Palmqvist, Anders
    Chalmers tekniska högskola, Göteborg.
    On the activity and stability of Sr3NiPtO6 and Sr3CuPtO6 as electrocatalysts for the oxygen reduction reaction in a polymer electrolyte fuel cell2007Inngår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 168, nr 2, s. 346-350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sr3NiPtO6 and Sr3CUPtO6 were evaluated as low-platinum alternative oxygen reduction catalysts in a solid polymer electrolyte fuel cell at 80 degrees C. The oxides were synthesised using a new method based on an organometallic precursor route. The electrochemical evaluation showed similar oxygen reduction performance for Sr3NiPtO6 and Sr3CUPtO6, with a slightly higher activity for Sr3NiPtO6. In comparison with the oxides, the oxygen reduction activity for a commercial Pt/C catalyst was approximately 10 times higher. XRD analysis of the used electrodes revealed that the oxides were not stable in the PEMFC environment, and converted into platinum during operation. Elemental analysis of the used electrodes also showed a difference in platinum formation, where the platinum content on the surface of the electrode facing the gas diffusion layer was several times higher for Sr3NiPtO6 than Sr3CUPtO6. This indicates that the Sr3NiPtO6 electrode may be more susceptible to platinum migration.

  • 103.
    Kluczny, Maksymilian
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Synthesis and Electrochemical Evaluation of Perovskite related oxide for Active Cathode for Solid Oxide Fuel Cells (SOFCs)2017Independent thesis Advanced level (degree of Master (Two Years)), 80 poäng / 120 hpOppgave
    Abstract [en]

    Solid oxide fuel cells are used as stationary power plants for electricity production. Despite having a very high efficiency of 90% they haven’t gained a world-wide commercial usage, due to their very high operating temperatures, and high production cost. However, there is a lot of ongoing research with the aim of developing intermediate-temperature solid oxide fuel cells (IT-SOFCs) that could operate at temperatures below 800°C.

    Cathodes are the most studied components of IT-SOFCs, since decreasing operating temperature results in slow oxygen reduction reaction(ORR) kinetics and large polarization losses. Perovskite related metal oxides have become very popular materials that could make suitable cathodes for IT-SOFCs. In this work an evaluation of several materials belonging to three different material groups have been studied: single layer perovskites, with a general formula of ABO3, double layer perovskites, with a general formula of AA’B2O6 and Ruddlesden-Popper phase, with a general formula of An+1BnO3n+1. Power generating capabilities of those materials have been studied on an electrolyte supported cell, cathode/LSGM9182/Ni-Fe. IR drop and overpotential of the cathode was measured and activation energy of the ORR for each material has been calculated.

    The double layer perovskite cobaltites offer a significant drop in overpotential, increase in conductivity compared to their single layer counterpart, while being able to generate significant amount of power. Ruddlesden-Popper phase materials offer the lowest activation energy values amongst the researched materials, but offer limited power generation values in the setup they were tested. Both of double layer perovskites and Ruddlesden-Popper based materials have opportunities for their performance to be improved.

  • 104.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Adibi, P. Tabib Zadeh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Trybom, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Di Benedetto, Luigi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selective Growth of B- and C-Doped SiGe Layers in Unprocessed and Recessed Si Openings for p-type Metal-Oxide-Semiconductor Field-Effect Transistors Application2010Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, nr 6, s. H633-H637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work presents the pattern dependency of the selective epitaxial growth of boron- and carbon-doped SiGe layers in recessed and unprocessed openings. The layer profile is dependent on deposition time, chip layout, and growth parameters. Carbon and boron doping compensates for the strain in SiGe layers, and when both dopants are introduced, the strain reduction is additive. The incorporation of boron and carbon in the SiGe matrix is a competitive action. The concentration of carbon decreases, whereas the boron amount increases in SiGe layers with higher Ge content. In recessed openings, the Ge content is independent of the recess depth. The strain amount in the grown layers is graded vertically, which is due to the thickness of the epilayer exceeding the critical thickness.

  • 105.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Adibi, P. Tabib Zadeh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Trybom, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Di Benedetto, Luigi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selective growth of B- and C-doped SiGe layers in unprocessed and recessed Si openings for pMOSFET application2009Inngår i: EUROCVD 17 / CVD 17, Electrochemical Society, 2009, nr 8 PART 1, s. 81-88Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This work presents pattern dependency of selective epitaxial growth of boron- or carbon-doped SiGe layers in recessed or unprocessed openings. The layer profile and quality of epi-layers were found to be dependent on chip layout and the growth parameters. Carbon- and boron-doping compensated the strain in SiGe layers and when both dopants are introduced the strain reduction was additive. The incorporation of boron and carbon in SiGe matrix showed to be a competitive action. The concentration of carbon decreased when the boron amount increased in SiGe layers with higher Ge content.

  • 106.
    Kortsdottir, Katrin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindström, Rakel
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Åkermark, Torbjörn
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Influence of toluene contamination at the hydrogen Pt/C anode in a proton exchange membrane fuel cell2010Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 55, nr 26, s. 7643-7651Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For fuel cells run on hydrogen reformate, traces of hydrocarbon contaminants in the hydrogen gas may be a concern for the performance and lifetime of the fuel cell. This study focuses on the influence of low concentrations of toluene on the adsorption and deactivation chemistry in a proton exchange membrane (PEM) fuel cell. For this purpose cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques were employed. Results from adsorption and desorption (by oxidation or reduction) experiments performed in a humidified nitrogen or hydrogen flow in a fuel cell test cell with a mass spectrometer system connected to the outlet are presented. The influence of adsorption potential, temperature, and humidity are discussed. The results show that toluene adsorbs on the catalyst surface in a broad potential window, up to at least 0.85 V versus RHE at 80 degrees C. Adsorbed toluene oxidizes to CO2 with peak potentials above 1.0V for temperatures below 95 degrees C. Some desorption of toluene (or reduced products) may take place at potentials below 0V. In a hydrogen flow, toluene contamination in per mille concentrations leads to a continuous growth of the charge transfer resistance, while a 10-fold dilution of the toluene concentration resulted in a low and constant charge transfer resistance even for longer exposures. This indicates that a competition between toluene and hydrogen may take place on the active platinum surface at the anode.

  • 107. Kravchenko, T A
    et al.
    Krysanov, V A
    Stolpovskii, A S
    Filatov, G A
    Zolotukhina, E V
    Zagorodni, Andrei A.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Contribution of dimensional factor to the potential of copper-containing electron-ion exchangers2006Inngår i: Russian journal of electrochemistry, ISSN 1023-1935, E-ISSN 1608-3342, Vol. 42, nr 3, s. 233-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The average size of copper particles in copper-containing electron-ion exchangers is determined with the aid of microscopy and x-ray diffractornetry. The results are used to calculate the contribution made by a dimensional factor to the electrode potential. Compared to the potential of compact copper, the potential shift in the negative direction measured experimentally falls within the region of calculated values. The average size of copper particles remains practically unchanged after contact with a copper sulfate solution. testifying to stabilization of an ultradisperse state of copper particles by a polymer matrix.

  • 108.
    Larsson, Michael
    et al.
    Mittuniversitetet.
    Galandrin, Elodie
    Mittuniversitetet.
    Högberg, Hans-Erik
    Mittuniversitetet.
    Diastereoselective addition of organozinc reagents to 2-alkyl-3-(arylsulfanyl)propanals2004Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 60, nr 47, s. 10659-10669Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The preparation of compounds incorporating the 3-hydroxy-2-methyl-1-alkyl moiety of high diastereomeric purity is described. Such compounds can serve as potential building blocks for the preparation of several kinds of natural products. Diastereoselective synthesis of two potential pine sawfly pheromone components, one the pure racemic threo-isomer of 3-methylpentadecan-2-ol and the other the racemic erythro-isomer of 3-methyltridecan-2-ol are described. The diastereoselective addition of R2Zn (R = Me, Et and n-Bu) to several 2-alkyl-3-(arylsulfanyl)propanals in the presence of a Lewis acid and CH2Cl2 as solvent was studied. An excellent diastereomeric ratio (95/5 anti-Cram/Cram) was obtained with 2-[(phenylsulfanyl)methyl]pentanal, 2-[(phenylsulfanyl)methyl]decanal and 2-[(phenylsulfanyl)methyl]dodecanal and Me2Zn in the presence of TiCl4.

  • 109.
    Leandri, Valentina
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Pizzichetti, Angela Raffaella Pia
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Xu, Bo
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Franchi, Daniele
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Zhang, Wei
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Benesperi, Iacopo
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Freitag, Marina
    Uppsala Univ, Angstrom Lab, Dept Chem, Div Phys Chem,Ctr Mol Devices, Box 523, SE-75120 Uppsala, Sweden..
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. DUT, DUT KTH Joint Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Gardner, James M.
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Tillämpad fysikalisk kemi.
    Exploring the Optical and Electrochemical Properties of Homoleptic versus Heteroleptic Diimine Copper(I) Complexes2019Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, nr 18, s. 12167-12177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to ligand scrambling, the synthesis and investigation of the properties of heteroleptic Cu(I) complexes can be a challenging task. In this work, we have studied the optical and electrochemical properties of a series of homoleptic complexes, such as [Cu(dbda)(2)](+), [Cu(dmp)(2)](+), [Cu(Br-dmp)(2)](+), [Cu(bcp)(2)](+), [Cu(dsbtmp)(2)](+), [Cu(biq)(2)](+), and [Cu(dap)(2)](+) in solution, and those of their heteroleptics [Cu(dbda)(dmp)](+), [Cu(dbda)(Br-dmp)](+), [Cu(dbda)(bcp)](+), [Cu(dbda)(dsbtmp))(+), [Cu(dbda)(biq)](+), [Cu(dbda)(dap)](+) adsorbed on the surface of anatase TiO2 (dbda = 6,6'-dimethyl-2,2'-bipyridine-4,4'-dibenzoic acid; dmp = 2,9-dimethyl-1,10-phenanthroline; Br-dmp = 5-bromo 2,9-dimethyl-1,10-phenanthroline; bcp = bathocuproine or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; dsbtmp = 2,9-di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline; biq = 2,2'-biquinoline; dap = 2,9-dianisyl-1,10-phenanthroline). We show that the maximum absorption wavelengths of the heteroleptic complexes on TiO2 can be reasonably predicted from those of the homoleptic complexes in solution through a simple linear relation, whereas the prediction of their redox properties is less trivial. In the latter case, two different linear patterns emerge: one including the ligands bcp, biq, and dap and another one including the ligands dmp, Br-dmp, and dsbtmp. We offer an interpretation of the data based on the chemical structure of the ligands. On one hand, ligands bcp, biq, and dap possess a more extended pi-conjugated system, which gives a more prominent contribution to the overall redox properties of the ligand dbda. On the other hand, the ligands dmp, Br-dmp, and dsbtmp are all phenanthroline-based containing alkyl substituents and contribute less than dbda to the overall redox properties.

  • 110. Lee, Bao-Lin
    et al.
    Karkas, Markus D.
    Johnston, Eric V.
    Inge, Andrew K.
    Tran, Lien-Hoa
    Xu, Yunhua
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Hansson, Örjan
    Zou, Xiaodong
    Åkermark, Björn
    Synthesis and Characterization of Oligonuclear Ru, Co and Cu Oxidation Catalysts2010Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 34, s. 5462-5470Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we report the preparation and crystal structures of three new oligonuclear complexes, Ru-2(bbpmp)(mu-OAc)(3) (4), [Co-2(bbpmp)(mu-OAc)(mu-OMe)](PF6) (5), [Cu-4(Hbbpmp)(2)(mu-OAc)(H2O)(2)](OAc)(PF6)(2) (6) {H(3)bbpmp = 2,6-bis[(2-hydroxybenzyl)-(2-pyridylmethyl)aminomethyl]-4-methylphenol (3)}. The structures of the complexes were determined by single-crystal X-ray diffraction. The oxidation states of ruthenium, cobalt and copper in the complexes are +3, +3 and +2, respectively. In 4 and 5, Ru-III and Co-III are coordinated to four oxygen and two nitrogen atoms in an octahedral geometry, while in 6, Cu-II adopts both octahedral (CuN2O4) and square-pyramidal (CuN2O3) geometry. The potential of the three complexes as oxidation catalysts has been investigated.

  • 111. Lee, H.
    et al.
    Wu, X.
    Yang, X.
    Sun, Licheng
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Ligand-Controlled Electrodeposition of Highly Intrinsically Active and Optically Transparent NiFeOxHy Film as a Water Oxidation Electrocatalyst2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 23, s. 4690-4694Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly intrinsically active and optically transparent NiFeOxHy water oxidation catalyst was prepared by electrodeposition of [Ni(C12-tpen)](ClO4)2 complex (Ni−C12). This NiFeOxHy film has a current density of 10 mA cm−2 with an overpotential (η) of only 298 mV at nanomolar concentration and the current density of 10 mA cm−2 remains constant over 22 h in 1 m KOH. The extremely high turnover frequency of 0.51 s−1 was obtained with η of 300 mV. More importantly, such outstanding activity and transparency (optical loss <0.5 %) of the NiFeOxHy film are attributed to a ligand effect of the dodecyl substituent in Ni−C12, which enables its future application in solar water splitting.

  • 112. Lee, Jookyeong
    et al.
    Choi, Eun Jung
    Varga, Imre
    Claesson, Per M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Yun, Sang-Ho
    Song, Changsik
    Terpyridine-functionalized stimuli-responsive microgels and their assembly through metal-ligand interactions2018Inngår i: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 9, nr 8, s. 1032-1039Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We developed a terpyridine-functionalized microgel (tpy-mG) for its supramolecular assembly. Tpy-mG was synthesized by amidation between 3-(4-([2,2':6',2 ''-terpyridin]-4'-yl)phenoxy) propan-1-amine and carboxylates of a thermo-responsive p(NIPAM-co-MAA) microgel (A-mG), which was synthesized by emulsion polymerization. After decorating terpyridine, its effects on the hydrodynamic radius, volume phase transition temperature (VPTT), and the colloidal stability of the microgel were investigated. Tpy-mG can be assembled reversibly with several metal ions (Ni2+, Fe2+, Co2+, or Zn2+), and interestingly the assembled tpy-mG-M2+ showed different rheological properties depending on the metal ion type; the weakly bound ions (Co2+, Zn2+) indicated fast dynamics for "inter-particular" exchange, resulting in much higher storage (G') and loss (G '') moduli. Photocatalysts such as Ru dyes can be easily introduced into tpy-mG via metal-ligand interactions, and the photooxidation of benzylamine was tested. The free Ru dye showed almost the same conversions at 25 and 50 degrees C, whereas the assembled Ru-tpy-mG-Mg2+ displayed reduced conversion at 50 degrees C (>VPTT). This is suggested to be due to the collapsed or "locked" structure around the photocatalytic center (Ru). Tpy-mG can be utilized as a good platform for developing responsive functional materials via reversible metal-ligand complexation.

  • 113.
    Li, Xin
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Minaev, Boris F.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi.
    Tian, He
    E China Univ Sci & Technol, Key Lab Adv Mat, Shanghai 200237, Peoples R China.;E China Univ Sci & Technol, Inst Fine Chem, Shanghai 200237, Peoples R China..
    Theoretical Study of Phosphorescence of Iridium Complexes with Fluorine-Substituted Phenylpyridine Ligands2011Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 16, s. 2517-2524Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Time-dependent density functional theory (TD-DFT) with linear and quadratic response approaches was applied to calculate absorption and luminescence spectra of a number of facial and meridional iridium complexes with fluorine-substituted phenylpyridine (F(n)ppy) ligands. The absorption and luminescence spectra were studied to simulate the photophysical properties of electroluminescent devices fabricated on the basis of these iridium complexes used to increase spin-orbit coupling and the triplet-state blue emission of the corresponding organic light-emitting diodes (OLEDs). By using the quadratic response technique, the phosphorescence radiative rate constant and lifetime of the studied iridium complexes were calculated through spin-orbit coupling perturbation and compared with the measured data in experiments. A satisfactory agreement between these data permits us to guide improvements in the design of phosphorescence-based OLEDs by predicting the structure-property relationships through quantum chemical calculations.

  • 114.
    Lindberg, Jonas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Endrodi, Balazs
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi. Univ Szeged, Dept Phys Chem & Mat Sci, H-6720 Szeged, Hungary..
    Avall, Gustav
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Johansson, Patrik
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Cornell, Ann M.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Tillämpad elektrokemi.
    Li Salt Anion Effect on O-2 Solubility in an Li-O-2 Battery2018Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, nr 4, s. 1913-1920Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For the promising Li-O-2 battery to be commercialized, further understanding of its constituents is needed. This study deals with the role of O-2 in Li-O-2 batteries, both its influence on electrochemical performance and its solubility in lithium-salt-containing dimethyl sulfoxide (DMSO) electrolytes. Experimentally, the electrochemical performance was evaluated using cylindrical ultramicroelectrodes. Two independent techniques, using a mass spectrometer and an optical sensor, were used to evaluate the O-2 solubility, expressed as Henry's constant. Furthermore, the ionic conductivity, dynamic viscosity, and density were also measured. Density functional theory calculations were made of the interaction energy between O-2 and the different species in the electrolytes. When varying O-2 partial pressure, the current was larger at high pressures confirming that the O-2 concentration is of key importance when studying the kinetics of this system. Compared with neat DMSO, the O-2 solubility increased with addition of LiTFSI and decreased with addition of LiClO4, indicating that the salt influences the solubility. This solubility trend is best explained in terms of apparent molar volume and interaction energy between O-2 and the salt anion. In conclusion, this study shows the importance of O-2 concentration, not just its partial pressure, and that the choice of Li salt can make this concentration increase or decrease.

  • 115.
    Lindsjo, Martin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Kloo, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Dimorphic (Ba GaCl4 (2))(3)center dot 2C(6)H(6): a case of coordination extremes2010Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 39, nr 6, s. 1467-1469Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new dimorphic tris[bariumbis(tetrachloro gallate]) bisbenzene formed by the same molecular building blocks have been isolated and structurally characterized, showing an unprecedented inorganic as well as mixed organic/inorganic coordination.

  • 116.
    Lindström, Rakel
    Göteborg University, Department of Chemistry.
    On the chemistry of atmospheric corrosion: a laboratory study on Zn, Mag and Mg-Al alloys2003Doktoravhandling, med artikler (Annet vitenskapelig)
  • 117.
    Lindström, Rakel
    et al.
    Göteborg University, Department of Inorganic Chemistry.
    Johansson, Lars-Gunnar
    Göteborg University, Department of Inorganic Chemistry .
    Svensson, Jan-Erik
    Chalmers, Inorganic Environmental Chemistry.
    The atmospheric corrosion of magnesium and magnesium alloys, a laboratory study2002Inngår i: Proceeding paper, 2002Konferansepaper (Fagfellevurdert)
  • 118.
    Lousada, Cláudio M.
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialteknologi.
    Fernandes, Ricardo M. F.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Tarakina, Nadezda V.
    Soroka, Inna L.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Synthesis of copper hydride (CuH) from CuCO3·Cu(OH)2 – a path to electrically conductive thin films of Cu2017Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, nr 20, s. 6533-6543Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 119.
    Lousada, Cláudio M.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Trummer, Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Reactivity of H2O2 towards different UO2-based materials: The relative impact of radiolysis products revisited2013Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 434, nr 1/3, s. 434-439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reactivity of doped UO2 such as SIMFUEL towards H2O2 has been shown to be fairly similar to that of pure UO2. However, the oxidative dissolution yield, i.e. the ratio between the amount of dissolved uranium and the amount of consumed H2O2 is significantly lower for doped UO2. In this work we have studied the mechanistic difference between SIMFUEL and pure UO2. H2O2 can be catalytically decomposed on UO2 in competition with the redox process in which U(IV) is oxidized. The latter process leads to the dissolution of oxidized uranium. The first step in the catalytic decomposition is the formation of hydroxyl radicals. The presence of hydroxyl radicals was verified using Tris buffer as a radical scavenger. For both UO2 and SIMFUEL pellets, significant amounts of hydroxyl radicals were formed. The results also show that the difference in dissolution yield between the two materials can mainly be attributed to differences in the redox reactivity. Based on this, the rate constants for electron transfer were revised and the relative impact of the radiolytic oxidants in oxidative dissolution of UO2 and SIMFUEL pellets were calculated. The impact of H2O2 is shown to be slightly reduced.

  • 120.
    Ma, Gui-Bin
    et al.
    KTH, Tidigare Institutioner, Kemi.
    Kritikos, M.
    Maliarik, Mikhail
    KTH, Tidigare Institutioner, Kemi.
    Glaser, Julius
    KTH, Tidigare Institutioner, Kemi.
    Modification of binuclear Pt-Tl bonded complexes by attaching bipyridine ligands to the thallium site2004Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 43, nr 14, s. 4328-4340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Complex formation of monomeric thallium(III) species with 2,2'-bipyridine (bipy) in dimethyl sulfoxide (dmso) and acetonitrile solutions was studied by means of multinuclear (H-1, C-13, and (TI)-T-205) NMR spectroscopy. For the first time, NMR signals of the individual species [TI(bipy)(m)(SoIV)](3+) (M = 1-3) were observed despite intensive ligand and solvent exchange processes. The tris(bipy) complex was crystallized as [TI(biPY)(3)(dmso)](ClO4)(3)(dMSO)(2) (1), and its crystal structure determined. In this compound, thallium is seven-coordinated; it is bonded to six nitrogen atoms of the three bipy molecules and to an oxygen atom of dmso. Metal-metal bonded binuclear complexes [(NC)(5)Pt-TI(CN)(n)(SoIV)](n-) (n = 0-3) have been modified by attaching bipy molecules to the thallium atom. A reaction between [(NC)(5)Pt-TI(dMSO)(4)](s) and 2,2'-bipyridine in dimethyl sulfoxide solution results in the formation of a new complex, [(NC)(5)Pt-TI(bipy)(solv)]. The presence of a direct Pt-TI bond in the complex is convincingly confirmed by a very strong one-bond Pt-195-(TI)-T-205 spin-spin coupling ((1)J((195)pt-(TI)-T-205) = 64.9 kHz) detected in both Pt-195 and (TI)-T-205 NMR spectra. In solutions containing free cyanide, coordination of CN- to the thallium atom occurs, and the complex [(NC)(5)Pt-TI(bipy)(CN)(solv)](-) ((1)J(Pt-195-(TI)-T-205) = 50.1 kHz) is formed as well. Two metal-metal bonded compounds containing bipy as a ligand were crystallized and their structures determined by X-ray diffractometry: [(NC)(5)Pt-TI(bipy)(dMSO)(3)] (2) and [(NC)(5)Pt-TI(biPY)(2)] (3). The Pt-TI bonding distances in the compounds, 2.6187(7) and 2.6117(5) Angstrom, respectively, are among the shortest reported separations between these two metals. The corresponding force constants in the molecules, 1.38 and 1.68 N/cm, respectively, were calculated using Raman stretching frequencies of the Pt-TI vibrations and are characteristic for a single metal-metal bond. Electronic absorption spectra were recorded for the [(NC)(5)Pt-TI(bipy)(m)(solv)] compounds, and the optical transition was attributed to the metal-metal bond assigned.

  • 121.
    Malm, B. Gunnar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Noise Properties of High-Mobility, 80 nm Gate Length MOSFETs on Supercritical Virtual Substrates2008Inngår i: SIGE, GE, AND RELATED COMPOUNDS 3: MATERIALS, PROCESSING, AND DEVICES   : MATERIALS, PROCESSING, AND DEVICES / [ed] Harame D; Caymax M; Koester S; Miyazaki S; Rim K; Tillack B; Boquet J; Cressier J; Masini G; Reznicek A; Takagi S, 2008, Vol. 16, nr 10, s. 529-537Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It was found that for strained Si channel layers of supercritical thickness oil relaxed SiGe virtual substrates, the 1/f noise oil,average is maintained at the same level as in unstrained devices. Short gate length nMOSFETs were analyzed statistically and the noise level variation, across a large number of samples, was similar in strained and unstrained devices. The obtained noise level variation was partly related to gate length fluctuations across the wafer, which was evident from a small V-T fluctuation.

  • 122.
    Mellgren, Niklas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Brown, Shelley
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Vynnycky, Michael
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Impedance as a Tool for Investigating Aging in Lithium-Ion Porous Electrodes: I. Physically Based Electrochemical Model2008Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, nr 4, s. A304-A319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrochemical impedance spectroscopy is potentially a powerful diagnostic tool for the investigation of the effects of aging in porous electrodes. A physically based three-electrode model was developed for a LixNi0.8Co0.15Al0.05O2 composite porous electrode with three porous separators and a reference electrode between a current collector and a plane electrode. Two effects of aging were modeled for this particular electrode chemistry, namely, a resistive corrosion layer on the current collector and a contact resistance between the electronic conductor and the active material of the porous electrode. The derivation of an analytical solution for the impedances between each pair of electrodes in this model yielded a computationally fast, versatile, and modular formulation. The solution was used to study the impact of selected components of the physical model on the impedance spectrum of the porous electrode for a physically relevant base case. Approximating the active material particles as spherical or flake-shaped particles, lognormally or Dirac distributed in size, revealed that the distribution has a negligible impact while the shape makes a noticeable difference. The main aging-related parameters were shown to have quite distinct effects on the impedance spectrum, which is essential for the regression of experimental data and the study of aging hypotheses.

  • 123.
    Mellgren, Niklas
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Vynnycky, Michael
    Dahlkild, Anders
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Porous Electrode and Nonequilibrium Water Transport Modelling in Polymer Electrolyte Fuel CellsManuskript (Annet vitenskapelig)
    Abstract [en]

    Recent years have seen the appearance of numerous modelling studies of the polymer electrolyte fuel cell. However, in spite of observations in different studies that a model for a cell operating under single-phase conditions must include nonequilibrium water transport and must spatially resolve the porous electrodes in order to capture the behaviour of the cell correctly, there are only very few models in the literature that simultaneously do both. This paper, however, formulates such a model and considers a one-dimensional version of it in a parameter study. In future work, the model will be used to calibrate model parameters against experiments and study the operation of cells in higher dimensions.

  • 124.
    Meyer, Gerd
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi.
    Small cause - Great effect: What the 4f(n+1)5d(0) -> 4f(n)5d(1) configuration crossover does to the chemistry of divalent rare-earth halides and coordination compounds2019Inngår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 270, s. 324-334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The rare-earth elements in the divalent state, i.e. with oxidation number + 2, may either have the electron configuration 4f(n+1)5d degrees(symbolized as R2+) or 4f(n)5d(1) (R(3+)e(-)). As R2+ (R = Eu, Yb, Sm, Tm, Dy, Nd) they can either be contained in extended solids as in the insulating diiodides RI2, or in coordination complexes such as samarocene, Kagan's reagent, or TmI2(DME)(3). In the case of R(3+)e(-), the "excess" d electron can either be delocalized and cause (semi)metallic behavior in extended solids, e.g. in LaI2, or localized with the R(3+)e(-) = 4f(n)5d(1) ion trapped in a coordination complex with (super)bulky ligands such as in [K(2.2.2-crypt)][LaCp ''(3)]. Thus, the seemingly small cause of a one-electron configuration crossover, 4f(n+1)5d degrees <--> Hf(n)5d(1) has a large effect on the chemical behavior and physical properties of the respective compounds where atomic properties and ligand effects play important roles.

  • 125. Mironov, Oleg A.
    et al.
    Bischof, Steven M.
    Konnick, Michael M.
    Hashiguchi, Brian G.
    Ziatdinov, Vadim R.
    Goddard, III, William A.
    Ahlquist, Mårten
    California Institute of Technology, United States.
    Periana, Roy A.
    Using Reduced Catalysts for Oxidation Reactions: Mechanistic Studies of the “Periana-Catalytica” System for CH4 Oxidation2013Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, nr 39, s. 14644-14658Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Designing oxidation catalysts based on CH activation with reduced, low oxidation state species is a seeming dilemma given the proclivity for catalyst deactivation by overoxidation. This dilemma has been recognized in the Shilov system where reduced Pt-II is used to catalyze methane functionalization. Thus, it is generally accepted that key to replacing Pt-IV in that system with more practical oxidants is ensuring that the oxidant does not over-oxidize the reduced Pt-II species. The “Periana-Catalytica” system, which utilizes (bpym)-(PtCl2)-Cl-II in concentrated sulfuric acid solvent at 200 degrees C, is a highly stable catalyst for the selective, high yield oxy-functionalization of methane. In lieu of the over-oxidation dilemma, the high stability and observed rapid oxidation of (bpym)(PtCl2)-Cl-II to Pt-IV in the absence of methane would seem to contradict the originally proposed mechanism involving CH activation by a reduced Pt-II species. Mechanistic studies show that the originally proposed mechanism is incomplete and that while CH activation does proceed with Pt-II there is a solution to the over oxidation dilemma. Importantly, contrary to the accepted view to minimize Pt-II overoxidation, these studies also show that increasing that rate could increase the rate of catalysis and catalyst stability. The mechanistic basis for this counterintuitive prediction could help to guide the design of new catalysts for alkane oxidation that operate by CH activation.

  • 126. Mizuoka, K
    et al.
    Grenthe, Ingmar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Ikeda, Y
    Structural and kinetic studies on uranyl(V) carbonate complex using C-13 NMR spectroscopy2005Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 44, nr 13, s. 4472-4474Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have measured C-13 NMR spectra of uranyl(V) carbonate complex in D2O solution containing 1.003 M Na-2 (CO3)-C-13 at various temperatures. Two singlet signals corresponding to free and coordinated CO32- were observed at 169.13 and 106.70 ppm, respectively. From the peak area ratio, the structure of the uranyl(V) carbonate complex was determined as [(UO2)-O-V(CO3)(3)](5-). Furthermore, kinetic analyses of the exchange reaction of free and coordinated CO32- in [(UO2)-O-V(CO3)(3)](5-) were carried out using 13C NMR line-broadening. As a result, the first-order rate constant at 298 K and the activation parameters for CO32- exchange reaction in [(UO2)-O-V(CO3)(3)](5-) were evaluated as 1.13 x 10(3) s(-1) and Delta H-not equal = 62.0 +/- 0.7 KJ(.)mol(-1), Delta S-not equal = 22 +/- 3 J(.)mol(-1.)K(-1), respectively. We suggest that the exchange follows a dissociative mechanism as in the corresponding [(UO2)-O-VI(CO3)(3)](4-) complex.

  • 127. Nenert, Gwilherm
    et al.
    Fabelo, Oscar
    Forsberg, Kerstin
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk apparatteknik.
    Colin, Claire V.
    Rodriguez-Carvajal, Juan
    Structural and magnetic properties of the low-dimensional fluoride beta-FeF3(H2O)(2)center dot H2O2015Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 44, nr 31, s. 14130-14138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have reinvestigated the crystal structure of the low-dimensional fluoride beta-FeF3(H2O)(2)center dot H2O using high resolution neutron and X-ray diffraction data. Moreover we have studied the magnetic behavior of this material combining medium resolution and high flux neutron powder diffraction together with magnetic susceptibility measurements. This fluoride compound exhibits vertex-shared 1D Fe3+ octahedral chains, which are extended along the c-axis. The magnetic interactions between adjacent chains involve super-superexchange interactions via an extensive network of hydrogen bonds. This interchain hydrogen bonding scheme is sufficiently strong to induce a long range magnetic order appearing below T = 20(1) K. The magnetic order is characterized by the propagation vector k = (0, 0, 1/2), giving rise to a strictly antiferromagnetic structure where the Fe3+ spins are lying within the ab-plane. Magnetic exchange couplings extracted from magnetization measurements are found to be J(II)/k(b) = -18 K and J(perpendicular to)/k(b) = -3 K. These values are in good agreement with the neutron diffraction data, which show that the system became anti-ferromagnetically ordered at ca. T-N = 20(1) K.

  • 128.
    Neranon, Kitjanit
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Constitutional Dynamics of Bipyridine-Metal Complex SystemsManuskript (preprint) (Annet vitenskapelig)
  • 129.
    Nielsen, Fredrik
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    The Steady-state Approach: A Model Describing the Dynamics of Spent Nuclear Fuel Dissolution in Groundwater2007Doktoravhandling, med artikler (Annet vitenskapelig)
  • 130.
    Nielsen, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Ekeroth, Ella
    Studsvik Nuclear AB, Nyköping.
    Eriksen, Trygve E.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Simulation of radiation induced dissolution of spent nuclear fuel using the steady-state approach. A comparison to experimental data2008Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 374, nr 1-2, s. 286-289Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using the recently developed steady-state model for simulation of radiation induced dissolution of spent nuclear fuel in water we have estimated the rate of dissolution for relatively fresh fuel to 1.64 x 10(-9) Mol m(-2) s(-1). A series of experiments have been performed on fuel fragments in deoxygenated water containing 10 mM HCO3-. The dissolution rates obtained from these experiments range from 2.6 x 10(-10) to 1.6 x 10-9 Mol m(-2) s(-1). The leaching time in the experiments is 40 days or less and during this time the amount of released uranium increases linearly with time which indicates that the system has reached steady-state. The excellent agreement between the estimated dissolution rate and the dissolution rates obtained from the spent nuclear fuel leaching experiments indicates that the steady-state approach can indeed be used to predict the rate of spent nuclear fuel dissolution.

  • 131.
    Nielsen, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Geometrical alpha- and beta-dose distributions and production rates of radiolysis products in water in contact with spent nuclear fuel2006Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 359, nr 02-jan, s. 1-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mathematical model for the dose distribution and production rates of radiolysis products in water surrounding spent nuclear fuel has been developed, based on the geometrical and energetic properties of radiation. The nuclear fuel particle is divided into layers, from which the radiation emits. The water is likewise divided into layers, where the doses are distributed. The doses are stored in vectors which are added to determine the total dose rate. A complete inventory with over 200 radionuclides has been used as input data for the model. The purpose of the model is to describe the geometrical dose distribution as a function of fuel age and burn-up, to be used as input data for kinetic modeling of the fuel dissolution. The results show that the P-dose contribution close to the spent fuel surface is negligible. Also, the variation in the relative OC/P dose contribution between different ages and burn-ups is insignificant. The alpha- and beta-dose rates vary between different burn-ups of the same age; the younger the fuel is, the larger is the difference. Exponential functions have been fitted to the relations between fuel age and average dose rate, giving useful expressions for determining average dose rates for fuel ages other than those covered in this work.

  • 132.
    Nielsen, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi (stängd 20110630).
    Simulations of H2O2 concentration profiles in the water surrounding spent nuclear fuel taking mixed radiation fields and bulk reactions into account2008Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 374, nr 1-2, s. 281-285Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To simulate the dynamics of the concentration gradient of hydrogen peroxide in groundwater surrounding spent nuclear fuel under various conditions, a model has been developed. The model treats the water volume as a sequence of volume elements, and applies the processes that affect hydrogen peroxide concentration to each volume element. The surface steady-state concentrations of H2O2, and the time. to reach steady-state, have been determined under different conditions. The processes accounted for in the model are radiolytic production of H2O2 from alpha- and beta-radiation, surface reactions consuming H2O2, homogeneous reactions consuming H2O2, and diffusion. The system has been modeled mainly for different surface reaction rate constants and homogeneous (bulk) reaction rate constants. The simulations show that the surface concentration of H2O2 approaches the steady-state concentration very rapidly and that the impact of homogeneous (bulk) reactions consuming H2O2 On the steady-state concentration is significant.

  • 133.
    Nielsen, Fredrik
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Lundahl, Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Simulations of H2O2 concentration profiles in the water surrounding spent nuclear fuel2008Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 372, nr 1, s. 32-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple mathematical model describing the hydrogen peroxide concentration profile in water surrounding a spent nuclear fuel pellet as a function of time has been developed. The water volume is divided into smaller elements, and the processes that affect hydrogen peroxide concentration are applied to each volume element. The model includes production of H2O2 from alpha-radiolysis, surface reaction between H2O2 and UO2 and diffusion. Simulations show that the surface concentration of H2O2 increases fairly rapidly and approaches the steady-state concentration. The time to reach steady-state is sufficiently short to be neglected compared to the times of interest when simulating spent fuel dissolution under deep repository conditions. Consequently, the steady-state approach can be used to estimate the rate for radiation-induced spent nuclear fuel dissolution.

  • 134.
    Nilsson, Sara
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Influence of metallic fission products and self irradiation on the rate of spent nuclear fuel-matrix dissolution2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [sv]

    Denna licentiatavhandling behandlar effekten av två inneboende egenskaper (fissions produkter och egenbestrålning) hos utbränt kärnbränsle på hastigheten för strålningsinducerad upplösning av bränslematris (UO2). I ett framtida djupförvar kommer det utbrända kärnbränslet att deponeras 500 meter ner i berggrunden i en reducerande miljö. Under dessa förhållanden är UO2-matrisen själv en av de skyddande barriärerna mot frigörande av radionuklider, på grund av dess låga löslighet. När bränslet kommer i kontakt med vatten kommer U(IV) att oxideras till U(VI) av radiolysprodukter från vattnet och lösligheten för bränslematrisen kommer därmed att öka betydligt.

    De flesta tidigare studier har utförts på obestrålad UO2 som skiljer sig signifikant från utbränt kärnbränsle. I utbränt kärnbränsle är de flesta fissionsprodukterna och neutronaktivieringsprodukterna radioaktiva och bränslet kommer därför bli bestrålat av sig självt. Effekten av joniserande strålning på reaktiviteten för UO2(s) har undersökts här. UO2 (pulver och fragment av en kuts) bestrålades i en 60Co γ-källa eller framför en elektronaccelerator varpå reaktiviteten för UO2 studerades genom oxidation av UO2 med MnO4 -. Det visade sig att reaktiviteten för UO2 ökar när det blir bestrålat för första gången (<20 kGy). Effekten ökar med ökande dos tills den når ett maxvärde ~1.3 gånger reaktiviteten för obestrålad UO2 vid torrbestrålning. Vid våtbestrålning ökar en dos på 140 kGy reaktiviteten 2.5 gånger. Effekten verkar vara permanent.

    Tidigare studier har visat att H2O2 är den viktigaste oxidanten för upplösning av utbränt kärnbränsle under djupförvarsförhållanden. I vätgasatmosfär, som förväntas i ett djupförvar, har det visat sig att upplösningshastigheten är långsammare. Det har delvis förklarats med reaktionen mellan H2O2 och H2, som är väldigt långsam utan katalysator. Den katalytiska effekten av UO2 på den reaktionen har undersökts och det visades att den inte katalyseras av UO2.

    En annan möjlig katalysator för reaktionen är ε-partiklar (ädelmetallpartiklar bestående av Mo, Ru, Tc, Pd och Rh) som bildats av fissionsprodukterna. Pd är en välkänd katalysator för reduktion med H2. Den eventuella katalytiska effekten av Pd har undersökts här. Även en eventuell katalytisk effekt av Pd på reduktionen av U(VI) med H2 undersöktes, både i vattenfas och i UO2-kutsar innehållande olika mängder Pd (som en modell för ε-partiklar).

    Vi fann att Pd har en katalytisk effekt på reaktionen mellan H2O2 och H2 och andra ordningens hastighetskonstant är bestämd till (2.1±0.1)x10-5 m s-1. Pd har också en katalytisk effekt på reduktionen av U(VI) med H2 både i vattenlösning, hastighetskonstant (1.5±0.1)x10-5 m s-1, och i den fasta fasen. Hastighetskonstanten för processen i fast fas är 4x10-7 m s-1 och 7x10-6 m s-1 för kutsar med 1 respektive 3 % Pd. Dessa värden är väldigt nära diffusionsgränsen för den här typen av system. Den katalytiska effekten i den fasta fasen visar att upplösningen för 100 år gammalt bränsle kan stoppas helt. Vid 40 bar H2 krävs 10-20 ppm ädelmetallpartiklar och med 1 % ädelmetallpartiklar räcker det med 0.1 bar H2 för att stoppa upplösningen.

  • 135.
    Nilsson, Sara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    On the catalytic effect of Pd(s) on the reduction of UO22+ with H-2 in aqueous solution2008Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 374, nr 1-2, s. 290-292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The catalytic effect of Pd(s) (as a model for noble metal particles) on the reduction of UO22+ by H-2 has been studied experimentally. The experiments were performed in aqueous solution in an autoclave. The aqueous solutions were pressurized with H-2 or N-2 and the UO22+ concentration was measured as a function of time. The experiments clearly show that Pd catalyzes the reaction between UO22+ and H-2. The rate constant of the reaction was found to be close to diffusion controlled and independent of the H-2 pressure in the range 1.5-40 bar. The effect of a catalyzed reduction of U(VI) to U(IV) in the solid phase is also discussed.

  • 136.
    Nilsson, Sara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    Jonsson, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemi, Kärnkemi.
    On the catalytic effects of UO2(s) and Pd(s) on the reaction between H2O2 and H-2 in aqueous solution2008Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 372, nr 2-3, s. 160-163Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The possible catalytic effects of UO2 and Pd (as a model for noble metal particles) on the reaction between H2O2 and H2 have been studied experimentally. The experiments were performed in aqueous solution using an autoclave. The aqueous solutions were pressurized with H2 or N2 and the H2O2 concentration was measured as a function of time. The experiments clearly showed that Pd catalyzes the reaction between H2O2 and H2 while UO2 has no catalytic effect. The rate constant of the reaction between H2O2 and H2 catalyzed by Pd was found to be close to diffusion controlled and independent of the H2 pressure in the range 1-40 bar. The impact of the catalytic effect on the reaction between H2O2 and H2 on spent nuclear fuel dissolution is, however, fairly small. Other possible effects of noble metal particles are also discussed, e.g. reduction of U(VI) to U(IV) in the liquid and solid phase.

  • 137.
    Nylén, Linda
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Influence of the electrolyte on the electrode reactions in the chlorate process2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The chlorate process is very energy intensive and a major part of the production costs are for electrical energy. Since the electricity prices are constantly increasing and may also vary periodically, the chlorate plants may be forced to adjust their production rate to the price at each moment in order to minimise their costs. Variation of current load requires increased knowledge regarding the electrode behaviour in a wide current range. In this thesis, the aim was to study the impact of the electrolyte on the electrode reactions in order to reduce the energy consumption. The work has mainly been experimental and additionally mathematical modelling has been carried out. A wide current range has been investigated in order to increase the understanding of the phenomena and to obtain results useful for low-load operation during the periods of high electricity cost.

    To operate the anode as energy efficiently as possible, the anode potential should not exceed the critical potential (Ecr), where the slope of the anodic polarisation curve increases, most likely due to ruthenium(VIII)-formation, and where the side reaction of oxygen evolution increases. In this work, the influence of different electrolyte parameters on Ecr has been studied. It was shown that a higher chloride concentration and an increased temperature lowered Ecr, which was expected to increase the risk of exceeding Ecr. However, this was not observed due to a simultaneous favouring of the chloride oxidation. Hence it was concluded that the electrolyte parameters should be optimised so that the lowest possible anode potential is obtained, which would enable higher current densities without exceeding Ecr. A further conclusion is that the increased slope of the polarisation curve at Ecr was possibly related to the lower activity for chloride oxidation on ruthenium oxidised to ruthenium(VIII).

    At full-load operation, the cathode potential was shown to be rather independent of the electrolyte composition despite a large variation of electrolyte parameters. The cathode composition appears to be more critical than the electrolyte composition when aiming at reducing the energy consumption. A strategy to increase the cathode activity could be to in situ apply a catalytic film onto the electrode surface. Therefore, Y(III) was added to a chloride electrolyte in order to form a yttrium hydroxide film on the alkaline cathode surface during hydrogen evolution. The yttrium-hydroxide film activated reduction of water (hydrogen evolution) and hindered hypochlorite reduction, proton reduction and nitrate reduction. The inhibiting properties are important for the prevention of side reactions, which currently are avoided by reducing Cr(VI) of the electrolyte on the cathode, producing an inhibiting chromium-hydroxide film. The studies on Y(III) increase the expectations for finding alternatives to the toxic Cr(VI).

    The addition of chromate to the chlorate electrolyte gives a high cathodic current efficiency and chromate has buffering properties in the electrolyte. The role of the buffer has been investigated for the oxygen evolution from water (one possible anodic side reaction), as well as cathodic hydrogen evolution. Models have been developed for these systems to increase the understanding of the interaction between buffer, electrode reactions and mass transport; the results have been verified experimentally. The chromate buffer increased the limiting current significantly for the cathodic H+ reduction and the cathodic overpotential was reduced drastically at currents lower than the limited current. A too low overpotential could result in the cathodic protection being lost. The presence of chromate buffer increased the limiting current for the oxygen evolution from OH-. The modelling of these systems revealed that the homogeneous reactions connected to the electrode reactions were not in equilibrium at the electrode surface. Further, a good resolution of the interface at the electrode surface was crucial since the, for the electrode reactions, important buffering takes place in an nm-thick reaction layer.

  • 138.
    Nylén, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann M.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Investigation of the oxygen evolving electrode in pH-neutral electrolytes: Modelling and experiments of the RDE-cell2007Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, nr 13, s. 4513-4524Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A model has been developed to illustrate the complex interplay between the acidifying electrode reactions for oxygen evolution, mass transport and homogeneous reactions in pH-neutral electrolytes. Modelled polarisation curves of the oxygen evolution reaction were verified by polarisation curves experimentally measured in 5 M NaClO4 on a RDE of DSA material. The conditions in the simulations and in the experiments were similar to those in the chlorate process (high ionic strength, 70 degrees C, chromate-containing electrolyte, DSA electrode), in which the oxygen evolution reaction is one of the possible side reactions. The model predicted the concentration gradients of H+, OH-, CrO42- and HCrO4- during oxygen evolution on the RDE. It was found that an important part of the chromate buffering effect at high current densities occurs in a thin (in the order of nanometers) reaction layer at the anode. From comparisons between the model and experiments, a buffering reaction has been proposed. The most likely reaction for the chromate buffering in the investigated system is CrO42- reacting with water to HCrO4- and OH-. In the chlorate process, where chromate is a buffer and oxygen evolution is a side reaction, it is likely that chromate promotes oxygen evolution from OH-.

  • 139.
    Nylén, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann M.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Critical Anode Potential in the Chlorate Process2006Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 1, s. D14-D20Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anodic polarization curves on dimensionally stable anodes (DSAs) of RuO2/TiO2 in chlorate electrolyte bend to a higher Tafel slope at the critical potential (E-cr) of approximately 1.2 V vs Ag/AgCl. Operating the chlorate process above E-cr leads to increased oxygen evolution and higher potential losses. In this study the impact of different electrolyte parameters and electrolyte impurities on the risk of reaching/exceeding E-cr was investigated. A dependency of Cl- concentration on E-cr of about -90 mV/dec C-Cl(-) was found at pH 2. An addition of Na2Cr2O7 to chlorate electrolyte is necessary in order to keep a high current efficiency on the cathode but was found to increase the anode potential and thereby increase the risk of exceeding E-cr at galvanostatic operation. Additions of impurities as 30 g/L Na2SO4 or 100 ppm Si (added as SiO2) resulted in increased anode potentials, but adding 1.4 g/L KH2PO4 or 1 g/L HF did not have significant short-term impact on the potential. The anode potential as well as E-cr decreased with increased temperature. A high temperature is beneficial in terms of the decreased anode potential, which outweighs the negative effect of a decrease in Ecr.

  • 140.
    Nylén, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann M.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Effects of electrolyte parameters on the iron/steel cathode potential in the chlorate process2009Inngår i: Journal of Applied Electrochemistry, ISSN 0021-891X, E-ISSN 1572-8838, Vol. 39, nr 1, s. 71-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study focuses on how different electrolyte parameters of the chlorate process affect the cathode potential for hydrogen evolution on iron in a wide current-density range. The varied parameters were pH, temperature, mass transport conditions and the ionic concentrations of chloride, chlorate, chromate and hypochlorite. At lower current densities, where cathodic protection of the electrode material is important, the pH buffering capacity of the electrolyte influenced the potential to a large extent. It could be concluded that none of the electrolyte parameters had any major effects (< 50 mV) on the chlorate-cathode potential at industrially relevant current densities (around 3 kA m(-2)). Certainly, there is more voltage to gain from changing the cathode material than from modifying the electrolyte composition. This is exemplified by experiments on steel corroded from operation in a chlorate plant, which exhibits significantly higher activity for hydrogen evolution than polished steel or iron.

  • 141.
    Nylén, Linda
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Gustavsson, John
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cornell, Ann M.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Cathodic reactions on an iron RDE in the presence of Y(III)2008Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, nr 10, s. E136-E142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During electrolysis of a solution containing Y(III) ions, a hydrous Y(OH)(3) film forms in the alkaline layer close to a hydrogen-evolving cathode. The film hinders the reduction of dissolved oxygen and activates the reduction of water, hydrogen evolution. The ability to hinder certain reactions while catalyzing hydrogen evolution may be useful in electrolysis applications. In this work the electrochemical properties of an in situ formed yttrium-hydroxide film were studied on an iron rotating disk electrode (RDE) in 0.5 M NaCl with addition of YCl3, NaClO, and of NaNO3. It was found that the film also hinders the reduction of protons, hypochlorite ions, and nitrate ions. At low concentration of Y(III) or at high current density, when the hydrogen evolution was vigorous, no activation of hydrogen evolution was observed. Under these conditions the film still hindered the reduction of ions. The reactant in the catalyzed hydrogen evolution reaction is most likely water molecules within the hydrous film. Nitrate ions were easily reduced on an iron cathode when no Y(III) ions were present in the solution. When studying effects of yttrium addition to a chloride solution the use of YCl3, rather than Y(NO3)(3), as Y(III) source is recommended.

  • 142.
    Nyman, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    An Experimental and Theoretical Study of the Mass Transport in Lithium-Ion Battery Electrolytes2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Lithium‐ion batteries are particularly suitable as energy storage solutions in high power applications, such as hybrid electric vehicles. It is generally considered that one of the processes that limit the power density for lithium‐ion batteries is the mass transport in the electrolyte. Yet, it is still difficult to find a set of properties that fully describe the mass transport for the most common electrolytes. In this work, characterization studies of the mass transport were undertaken for two technically important lithium‐ion battery electrolytes: (1) a liquid electrolyte which consist of LiPF6 dissolved in ethyl methyl carbonate (EMC) and ethylene carbonate (EC) and, (2) a gel electrolyte which consists of LiPF6 dissolved in ethylene carbonate, propylene carbonate (PC) and poly(vinylidenefluoride‐hexafluoropropylene) (P(VdFHFP)).The mass transport in the electrolytes was characterized by combining several experiments. The Maxwell‐Stefan equation was used as basis for the characterization. Models of the transport were formulated from the equation and the apparent transport properties were identified. The characterization methods were first analyzed mathematically in order to establish at which conditions the characterization experiments should be performed. The values of the apparent transport properties were then obtained by optimizing the models to the experimental responses. In order to give the characterization results a comprehensible interpretation and to allow benchmarking of electrolytes, the concept of a normalized potential gradient was introduced.The characterization results of the liquid electrolyte were used in a full cell model of a LiNi0.8Co0.15Al0.05O2 | LiPF6 EC:EMC (3:7) | MAG‐10 cell. The model was developed to analyze the mass transport during a hybrid pulse power characterization (HPPC) test. The analysis was made with a method where the polarization was split up into parts each associated with a process within the cell. The optimum composition in terms of mass transport was found to lie between 0.5 and 1.2 mol/dm3 LiPF6 for the liquid electrolyte and between 5 and 7 wt. % LiPF6 for the gel electrolyte. Less amount of polymer in the gel electrolyte gave a faster mass transport. It was also found that the mass transport in the liquid electrolyte contributed to a major part of the polarization during HPPC tests.

  • 143.
    Nyman, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A Theoretical and Experimental Study of the Mass Transport in Gel Electrolytes: I. Mathematical Analysis of Characterization Method2011Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 158, nr 6, s. A628-A635Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mass transport of lithium ions is one of the major limitations to the performance of high-rate lithium-ion batteries. This paper presents an analysis of a mass transport characterization method for gel electrolytes. The method is based on a Maxwell-Stefan transport model, which takes into account the polymer as an active specie in the transport. Nine apparent transport properties are defined from the model and their dependence on the Maxwell-Stefan diffusivities and the thermodynamic enhancement factors are presented. The characterization method is analyzed by finding analytical expressions that describe the characterization experiments. From the expressions it can be seen how the nine apparent transport properties influence the experimental response. The conclusions of the analysis will be used later in a characterization of the gel electrolyte: LiPF6-ethylene carbonate (EC)-propylene carbonate (PC)-poly(vinylidenefluoride-hexafluoropropylene) P(VdF-HFP).

  • 144.
    Nyman, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Electrochemical characterisation and modelling of the mass transport phenomena in LiPF6-EC-EMC electrolyte2008Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, nr 22, s. 6356-6365Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The conductivity, the salt diffusion coefficient, the lithium-ion transport number and the thermodynamic factor of the salt and the solvent were reported for LiPF6 in EC:EMC (3:7) at 25 IC and for concentrations between 0.2 and 2.0 mol/d M3. The mass transport in the electrolyte was fully characterised by combining three types of electrochemical experiments; concentration cells, galvanostatic polarisation experiments and electrochemical impedance measurements with a mathematical description of the mass transport in the electrolyte. The apparent salt diffusion coefficient had a local maximum in the concentration range, while the viscosity-dependent salt diffusion coefficient decreased from 4.1 X 10-10 M2/s at 0.2 mol/d M3 to 4.4 x 10-11 M2/s at 2.0 mol/dM3. Both the thermodynamic factor and the conductivity varied strongly with the concentration. The conductivity had a maximum of 9.5 mS/cm at 1.0 mol/dm 3. The lithium-ion transport numberwith respect to the room decreased with increasing salt concentration, with a maximum of 0.37 at 0.2 molldm 3 in the concentration range. The Maxwell-Stefan diffusivities and the electrolyte potential drop in a lithium-ion battery at steady state were lastly calculated from the obtained transport properties. An analysis of the characterisation method was also done on the basis of the characterisation results.

  • 145.
    Nyman, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Behm, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    Lindbergh, N. Göran
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Tillämpad elektrokemi.
    A Theoretical and Experimental Study of the Mass Transport in Gel Electrolytes: II. Experimental Characterization of LiPF6-EC-PC-P(VdF-HFP)2011Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 158, nr 6, s. A636-A643Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mass transport in a gel consisting of LiPF6 dissolved in ethylene carbonate (EC), propylene carbonate (PC) and poly(vinylide-nefluoride-hexafluoropropylene) (P(VdF-HFP)) was characterized at 25 degrees C. Four diffusion coefficients, two transport numbers, one conductivity and two parameters describing the relationship between a concentration and a potential gradient were obtained in the characterization. The transport properties were obtained by optimizing a Maxwell-Stefan based transport model to data from four types of experiments. The transport model and the characterization method were analyzed in Part I. In order to give the results a comprehensible interpretation and to present a way of benchmarking electrolytes, we introduce the concept of a normalized potential gradient for gel electrolytes. The optimum composition range of the gel in terms of mass transport was found to lie between 5 and 7 wt % LiPF6 and as little polymer as possible without compromising the mechanical stability. It is suggested that measuring the normalized potential gradient can be used as a screening method when benchmarking electrolytes.

  • 146.
    Ogawa, Keita
    et al.
    Advanced Engineering Services Co..
    Takeda, Yasuo
    Advanced Engineering Services Co..
    Brown, Shelley
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Uno, Masatoshi
    Japan Aerospace Exploration Agency.
    Sone, Yoshitsugu
    Japan Aerospace Exploration Agency.
    Tanaka, Koji
    Japan Aerospace Exploration Agency.
    Hirose, Kazuyuki
    Japan Aerospace Exploration Agency.
    Tajima, Michio
    Japan Aerospace Exploration Agency.
    Saito, Hirobumi
    Japan Aerospace Exploration Agency.
    Calibration of the Lithium-Ion Secondary Battery for 'REIMEI'Inngår i: Journal of the Japanese Electrochemical SocietyArtikkel i tidsskrift (Annet vitenskapelig)
  • 147.
    Olsen, Vegard S.
    et al.
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Bazioti, Calliope
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Baldissera, Gustavo
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Azarov, Alexander
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Prytz, Oystein
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Persson, Clas
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Svensson, Bengt G.
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Kuznetsov, Andrej Y.
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Vines, Lasse
    Univ Oslo, Ctr Mat Sci & Nanotechnol, Dept Phys, POB 1048, N-0316 Oslo, Norway..
    Effects of Substrate and Post-Deposition Annealing on Structural and Optical Properties of (ZnO)(1-x)(GaN)x Films2019Inngår i: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 256, nr 6, artikkel-id 1800529Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structural and optical properties of magnetron sputtered thin films of (ZnO)(1-x)(GaN)(x) deposited on zinc oxide, sapphire, and silicon oxide are studied as a function of strain accumulation and postdeposition anneals at 600-800 degrees C. For the experimental conditions studied, we found that different amounts of tensile strain accumulated in the samples practically does not affect the strong bandbowing effect, that is, optical bandgap, observed in the asdeposited alloys. In its turn, postdeposition annealing results in a reduction of the tensile strain and dislocation density in the films, as measured by both X-ray diffraction and transmission electron microscopy, corroborating an increase in the crystal quality. In addition, the grain size is found to increase with annealing temperature, for example, mean values of 20 nm up to 50 nm were measured for the alloys with x=0.15. Meanwhile, the fullwidth at half maximum of the (0002) X-ray diffraction reflection increases with annealing temperature, but with only a small increase in bandgap energies for the x=0.15 sample. However, this observation was explained combining the experimental data and firstprinciples calculations based on density functional theory, showing that the increase in the amount of Ga-N bonds lowers the total energy of the system. As such, we conclude that the thermal treatments increase the Ga-N ordering, resulting in several contributions or a widening of the diffraction peaks.

  • 148. Olsson, Lars-Fride
    et al.
    Sandin, Karin
    Odselius, Rolf
    Kloo, Lars A.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    In vitro formation of nanocrystalline carbonate apatite - A structural and morphological analogue of atherosclerotic plaques2007Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 26, s. 4123-4127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The in vitro formation of carbonate apatite in solutions with ion concentrations comparable to those in human serum was studied. The composition and morphology of the resulting apatite precipitate displayed a hierarchical assembly of elongated plate-shaped nanocrystals of carbonate apatite analogous to previously characterized bioapatites formed in The main conclusion is that so-called bioapatites may form in vitro and that precipitation inhibitors most likely are essential for the prevention of spontaneous calcification at normal human serum ion concentrations.

  • 149. Ostman, M.
    et al.
    Wahlberg, Olle
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Martensson, A.
    Leachability and metal-binding capacity in ageing landfill material2008Inngår i: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 28, nr 1, s. 142-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to study the stability of landfilled heavy metals, landfill material from a combined household and industrial waste landfill was aerated for 14 months to simulate the natural ageing processes as air slowly begins to penetrate the landfill mass. During aeration, the pH of the landfill material decreased from around 8.6 to 8.1 and the carbon content also decreased. In order to investigate the possible fate of metals in ageing landfills, a four-stage sequential extraction technique was applied. The ability of the materials to bind metal ions by electrostatic attractions and to form stronger complexes was studied separately. The amount of exchangeable cations, the capacity to bind metal ions by electrostatic attraction and the capacity of the landfill material to complex copper ions were increased by the aeration process. However, results from the sequential analysis showed an increased solubility of sulphur and some metals (Cd, Co, Cu, Ni and Zn). Equilibrium speciation models (Medusa) indicated that the organic matter deposit had a significant capacity to bind metal ions provided that pH was sufficiently high. However, as carbonates are consumed over time, the risk for metal mobility increases. Therefore, the landfills can become an environmental risk, depending on variations in the solubility of metal ions due to changes in pH, redox status and the availability of organic material.

  • 150.
    Pan, Jinshan
    et al.
    KTH, Tidigare Institutioner                               , Kemi.
    Öijerholm, Johan
    KTH, Tidigare Institutioner                               , Kemi.
    Belonoshko, Anatoly
    KTH, Tidigare Institutioner                               , Fysik.
    Rosengren, Anders
    KTH, Tidigare Institutioner                               , Fysik.
    Leygraf, Christofer
    KTH, Tidigare Institutioner                               , Kemi.
    Self-diffusion activation energies in alpha-Al2O3 below 1000 degrees C: measurements and molecular dynamics calculation2004Inngår i: Philosophical Magazine Letters, ISSN 0950-0839, E-ISSN 1362-3036, Vol. 84, nr 12, s. 781-789Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Results from impedance spectroscopy measurements at temperatures between 400 and 1000&DEG; C, for single crystal and highly pure and dense polycrystalline &alpha;-Al2O3 samples with well-defined grain size, are compared with that from molecular dynamics calculation. Between 650 and 1000&DEG; C, the measured activation energy for conductivity is 1.5 eV for the single crystal, and increases from 1.6 to 2.4 eV as the grain size decreases from 15 to 0.5 &mu; m. The molecular dynamics calculation leads to the conclusion that the self-diffusion activation energy is about 1.5 eV for O and 1.0 eV for Al in single crystal &alpha;-Al2O3. The much higher mobility of O ions makes the O ions responsible for the conductivity of the single crystal oxide. It seems that the grain boundary leads to an increase in the activation energy. However, the quantitative influence of grain boundary still needs to be explained. Between 400 and 650&DEG; C, the measured activation energy is about 1.0 eV and independent of the grain size.

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