| 1. |
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| 2. |
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| 3. |
- Andersson, Cristina, 1969, et al.
(författare)
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Effect of different temperature cycle profiles on the crack propagation and microstructural evolution of Sn-3.8Ag-0.7Cu solder joints
- 2005
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Ingår i: 15th European Microelectronics and Packaging Conference and Exhibition, EMPC 2005 - Conference Programme and Proceedings. ; 2005, s. 523-528
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Konferensbidrag (refereegranskat)abstract
- Temperature cycling of real electronic components was carried out in a systematic manner at two different temperature profiles and in a single-chamber Heraeus climate cabinet. The first temperature profile ranged between -55°C and 100°C and the second between 0°C and 100°C. Top-side SMD components (chip resistors and Ball Grid Arrays (BGA)) were soldered with Sn-3.8Ag-0.7Cu lead free solder paste. Crack initiation and propagation was analyzed after every 500 cycles for each temperature cycling profile. Totally, 6500 cycles were run at both temperature profiles. Finite element modeling (FEM) calculations, for the analysis of strain and stress of 1206 chip joints were used to corroborate the experimental work results, especially regarding the crack initiation sites. Cracks were firstly visible for the temperature cycling ranging between -55°C and 100°C. The cracks observed were also visibly smaller for the temperature profile ranging between 0°C and 100°C, concluding that crack initiation and propagation was slightly slower for this temperature profile. Cracks continued to propagate as a function of temperature cycles. The reason for this difference in crack initiation and propagation was also analyzed.
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| 4. |
- Andersson, Cristina, 1969, et al.
(författare)
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Effect of different temperature cycling profiles on the crack initiation and propagation and of Sn-3.5Ag wave soldered joints
- 2007
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Ingår i: Microelectronics and Reliability. - : Elsevier BV. - 0026-2714. ; 47:2-3, s. 266-272
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of a test board with different electronic components was carried out at two different temperature profiles in a single-chamber climate cabinet. The first temperature profile ranged between 55 and 100 C and the second between 0 and 100 C. Hole mounted components and secondary side SMD components were wave soldered with an Sn–3.5Ag alloy. Joints of both dual in line(DIL) packages and ceramic chip capacitors were investigated. Crack initiation and propagation was analysed after every 500 cycles.In total, 6500 cycles were run at both temperature profiles and the observations from each profile were compared.For both kinds of components analysed, cracks were first visible for the temperature profile ranging between 55 and 100 C. For this temperature profile, and for DIL packages, cracks were visible already after 500 cycles, whereas for the other temperature profile, cracks initiated between 1000 and 1500 cycles. The cracks observed after 1500 cycles were visibly smaller for the temperature profile ranging between 0 and 100 C, concluding that crack initiation and propagation was slightly slower for this temperature profile. For the chip capacitors, cracks were first visible after 2000 cycles.
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| 5. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling aging effect on the shear strength, microstructure, IMC and initiation and propagation of surface mounted Sn-3.8Ag-0.7Cu and wave soldered Sn-3.5Ag ceramic chip components
- 2008
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Ingår i: IEEE Transactions on Components and Packaging Technologies. - 1521-3331. ; 31:2, s. 331-344
-
Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of electronic components was carried out at two different temperature profiles, the first ranging between -55°C and 100°C (TC1) and the second between 0°C and 100°C (TC2). Totally, 7000 cycles were run at TC1 and 14500 cycles at TC2. The test board’s top-side components were surface mounted using Sn-3.8Ag-0.7Cu solder alloy, and bottom side SMD components were wave soldered with Sn-3.5Ag alloy. The solder joint degradation was investigated as a function of cycle number by means of shear strength measurements and cross-sectioning. The shear strength drop was correlated to both crack initiation time and propagation rate, and Microstructural changes. The effect of manufacturing process (reflow versus wave soldering) and component size (0805 versus 0603 components) on the shear strength were also investigated.For both reflow and wave soldered components, the harsher the test environment the faster and largest the decrease in shear strength. The shear force is higher for the 0805 components compared to the 0603. The effect of component size on the residual shear strength is higher for the testing condition TC1. TC1 also seems to have a higher effect on the residual shear strength compared to TC2. The main difference between wave soldered and reflow soldered components is that the shear strength is in average higher for the wave soldered components compared to the reflow soldered. For the reflow soldered components using SAC, the microstructure coarsens, especially the Ag3Sn intermetallic particles. Furthermore, this alloy shows an increase of the IMC layer (Cu-Ni-Sn) thickness, and the IMC layer growth is controlled by a diffusion mechanism. The IMC growth coefficient is for the SAC system tested at TC1 0.0231 μm/hr1/2 (0.00053μm/hr) and for TC2 0.0054 μm/hr1/2 (2.9*10-5μm/hr). The microstructural changes during thermal cycling are a result of both static and strain-enhanced aging. For the wave soldered components the microstructure also became coarser, however, the IMC layer (Ni3Sn4) thickness did not change.The IMC layer growth does not affect the shear strength for the test conditions applied in this work. The shear strength decrease observed in the present work as a result of thermal cycling is a result of both microstructural coarsening and crack propagation inside the solder joint.
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| 6. |
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| 7. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling of lead-free Sn-3.8Ag-0.7Cu 388PBGA packages
- 2009
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Ingår i: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 21:2, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to assess the effect of different temperature cycling profiles on the reliability of lead-free 388 plastic ball grid array (PBGA) packages and to deeply understand crack initiation and propagation.Design/methodology/approach - Temperature cycling of Sn-3.8Ag-0.7Cu PBGA packages was carried out at two temperature profiles, the first ranging between - 55 degrees C and 100 degrees C (TC1) and the second between 0 degrees C and 100 degrees C (TC2). Crack initiation and propagation was analyzed periodically and totally 7,000 cycles were run for TO and 14,500 for TC2. Finite element modeling (FEM), for the analysis of strain and stress, was used to corroborate the experimental results.Findings - The paper finds that TC1 had a characteristic life of 5,415 cycles and TC2 of 14,094 cycles, resulting in an acceleration factor of 2.6 between both profiles. Cracks were first visible for TC1, after 2,500 cycles, and only after 4,000 cycles for TC2. The crack propagation rate was faster for TC1 compared to TC2, and faster at the package side compared to the substrate side. The difference in crack propagation rate between the package side and substrate side was much larger for TC1 compared to TC2. Cracks developed first at the package side, and were also larger compared to the substrate side. The Cu tracks on the substrate side affected the crack propagation sites and behaved as SMD. All cracks propagated through the solder and crack propagation was mainly intergranular. Crack propagation was very random and did not follow the distance to neutral point (DNP) theory. FEM corroborated the experimental results, showing both the same critical location of highest creep strain and the independence of DNP.Originality/value - Such extensive work on the reliability assessment of Pb-free 388 PBGA packages has never been performed. This work also corroborates the results from other studies showing the difference in behavior between Pb-free and Pb-containing alloys.
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| 8. |
- Sjöberg, Per-Olof, et al.
(författare)
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Sverige i halvledarvärlden – analys och förslag till strategi
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den brist på halvledare som industrin upplevt under 2021 har satt den annars tämligen anonyma halvledarindustrin i rampljuset såväl i Sverige som i Europa, USA och globalt. Hur länge denna brist kommer att bestå är en viktig fråga för industrin, som dock är svår att svara på. Enligt internationella analytiker kommer industrin att uppleva halvledarbrist fram till sommaren 2022 och eventuellt in på nästa höst eller eventuellt längre, varefter det föreligger en risk för överproduktion då lager förmodligen byggts upp bland avnämare. Erfarenheterna från tidigare halvledarbrister är att de så småningom övergår i överskott. Men den nuvarande bristen kan sannolikt kräva längre tid för detta än tidigare brister. Främsta skälet är att de halvledarfabriker som för närvarande är under uppbyggnad för att råda bot på bristen lider av samma överhettade försörjningskedjor som övrig industri, med förseningar av allt från vitala utrustningar till förbrukningsmateriel, och att det därför troligen kommer att ta längre tid än planerat att få dem i drift. Detta kan i värsta fall innebära att det rentav kan ta ett eller flera år längre tid än analytikerna förutspått innan försörjningsläget är normalt. Sverige är en del av det globala halvledarekosystemet – ett komplext ekosystem som kännetecknas av hög grad av arbetsfördelning, hög kapitalintensitet, hög kunskapsintensitet, långa produktionstider, stark internationalisering och starka inlåsningseffekter. Sverige interagerar med detta globala ekosystem på två sätt - som leverantör av produkter och tjänster i ett antal nischer där vi uppvisar global spetskompetens samt som avnämare av halvledarprodukter för industriella behov. Båda dessa sidor behöver stärkas för att a) våra SMF och stora företag ska kunna få tillgång till de halvledare och system byggda på halvledare som krävs för den produktion av produkter och tjänster som bidrar till Sveriges välstånd, b) svenska industriföretag ska kunna säkra tillgång till den kompetens och de tjänster som krävs då industrins produkter innehåller allt större mängd halvledare, och c) för att maximera möjligheterna för svenska halvledar- och elektronikinnovationer att hävda sig på världsmarknaden, och på så sätt bidra till landets välstånd. Det övergripande målet för Sverige bör vara att använda vår nationella styrka inom innovation som hävstång, och fokusera de starka specialiserade kompetenserna som finns här i landet, jämte långsiktiga investeringar i forskning inom halvledarteknik, systemdesign och halvledarmaterial, i syfte att med samlad kraft nå följande strategiska mål: 1) Etablera Sverige som ett halvledarinnovationsland genom att stärka vårt innovationssystem för halvledare och halvledarmaterial. 2) Få utväxling på de svenska investeringarna i forsknings- och innovationsinfrastruktur för design och produktion av halvledare. 3) Säkra och vidmakthåll en roll för Sverige i halvledarindustrin, inte minst genom svensk representation i de organ och församlingar som beslutar om framtida europeiska investeringar. För att nå dessa mål krävs stark samverkan mellan industri, akademi, institut och offentlig sektor, och långsiktiga såväl publika som privata investeringar i utbildning, forskningsinfrastruktur, test- och demonstrationsanläggningar och i startup- och scaleup-bolag. RISE åsikt är att Sverige därtill bör ta aktiv del i EU-initiativ som den europeiska halvledaralliansen (Alliance on Processor and Semiconductor Technologies) och European Chips Act. Påpekas bör att dessa mål är långsiktiga och kräver kontinuerligt arbete och finansiering under många år framöver. De löser inte industrins kortsiktiga behov av halvledare, och det kommer att ta tid att säkra industrins behov av halvledarkompetens. Med en väl genomförd strategi skulle dock dessa behov i högre grad kunna tillgodoses samtidigt som vårt lands bidrag till det globala halvledarekosystemet skulle växa kraftigt, till fromma för vårt gemensamma välstånd.
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| 9. |
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| 10. |
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| 11. |
- Akbari, Saeed, et al.
(författare)
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Ceramic Additive Manufacturing Potential for Power Electronics Packaging
- 2022
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Ingår i: IEEE Transactions on Components, Packaging, and Manufacturing Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 2156-3950 .- 2156-3985. ; 12:11, s. 1857-1866
-
Tidskriftsartikel (refereegranskat)abstract
- Compared with silicon-based power devices, wide band gap (WBG) semiconductor devices operate at significantly higher power densities required in applications such as electric vehicles and more electric airplanes. This necessitates development of power electronics packages with enhanced thermal characteristics that fulfil the electrical insulation requirements. The present research investigates the feasibility of using ceramic additive manufacturing (AM), also known as three-dimensional (3D) printing, to address thermal and electrical requirements in packaging gallium nitride (GaN) based high-electron-mobility transistors (HEMTs). The goal is to exploit design freedom and manufacturing flexibility provided by ceramic AM to fabricate power device packages with a lower junction-to-ambient thermal resistance (RθJA). Ceramic AM also enables incorporation of intricate 3D features into the package structure in order to control the isolation distance between the package source and drain contact pads. Moreover, AM allows to fabricate different parts of the packaging assembly as a single structure to avoid high thermal resistance interfaces. For example, the ceramic package and the ceramic heatsink can be printed as a single part without any bonding layer. Thermal simulations under different thermal loading and cooling conditions show the improvement of thermal performance of the package fabricated by ceramic AM. If assisted by an efficient cooling strategy, the proposed package has the potential to reduce RθJA by up to 48%. The results of the preliminary efforts to fabricate the ceramic package by AM are presented, and the challenges that have to be overcome for further development of this manufacturing method are recognized and discussed.
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| 12. |
- Akbari, Saaed, et al.
(författare)
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Effect of PCB cracks on thermal cycling reliability of passive microelectronic components with single-grained solder joints
- 2019
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Ingår i: Microelectronics and reliability. - : Elsevier BV. - 0026-2714 .- 1872-941X. ; 93, s. 61-71
-
Tidskriftsartikel (refereegranskat)abstract
- Lead-free tin-based solder joints often have a single-grained structure with random orientation and highly anisotropic properties. These alloys are typically stiffer than lead-based solders, hence transfer more stress to printed circuit boards (PCBs) during thermal cycling. This may lead to cracking of the PCB laminate close to the solder joints, which could increase the PCB flexibility, alleviate strain on the solder joints, and thereby enhance the solder fatigue life. If this happens during accelerated thermal cycling it may result in overestimating the lifetime of solder joints in field conditions. In this study, the grain structure of SAC305 solder joints connecting ceramic resistors to PCBs was studied using polarized light microscopy and was found to be mostly single-grained. After thermal cycling, cracks were observed in the PCB under the solder joints. These cracks were likely formed at the early stages of thermal cycling prior to damage initiation in the solder. A finite element model incorporating temperature-dependant anisotropic thermal and mechanical properties of single-grained solder joints is developed to study these observations in detail. The model is able to predict the location of damage initiation in the PCB and the solder joints of ceramic resistors with reasonable accuracy. It also shows that the PCB cracks of even very small lengths may significantly reduce accumulated creep strain and creep work in the solder joints. The proposed model is also able to evaluate the influence of solder anisotropy on damage evolution in the neighbouring (opposite) solder joints of a ceramic resistor.
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| 13. |
- Akbari, Saeed, et al.
(författare)
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Low Inductive SiC Power Electronics Module with Flexible PCB Interconnections and 3D Printed Casing
- 2022
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Ingår i: 2022 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9789189711396
-
Konferensbidrag (refereegranskat)abstract
- Silicon carbide (SiC) power devices are steadily increasing their market share in various power electronics applications. However, they require low-inductive packaging in order to realize their full potential. In this research, low-inductive layouts for half-bridge power modules, using a direct bonded copper (DBC) substrate, that are suitable for SiC power devices, were designed and tested. To reduce the negative effects of the switching transients on the gate voltage, flexible printed circuit boards (PCBs) were used to interconnect the gate and source pins of the module with the corresponding pads of the power chips. In addition, conductive springs were used as low inductive, solder-free contacts for the module power terminals. The module casing and lid were produced using additive manufacturing, also known as 3D printing, to create a compact design. It is shown that the inductance of this module is significantly lower than the commercially available modules.
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| 14. |
- Akbari, Saeed, et al.
(författare)
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Packaging Induced Stresses in Embedded and Molded GaN Power Electronics Components
- 2023
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Ingår i: Int. Conf. Therm., Mech. Multi-Phys. Simul. Exp. Microelectron. Microsyst., EuroSimE. - : Institute of Electrical and Electronics Engineers Inc..
-
Konferensbidrag (refereegranskat)abstract
- Residual stresses created during the packaging process can adversely affect the reliability of electronics components. We used incremental hole-drilling method, following the ASTM E 837-20 standard, to measure packaging induced residual stresses in discrete packages of power electronics components. For this purpose, we bonded a strain gauge on the surface of a Gallium Nitride (GaN) power component, drilled a hole through the thickness of the component in several incremental steps, recorded the relaxed strain data on the sample surface using the strain gauge, and finally calculated the residual stresses from the measured strain data. The recorded strains and the residual stresses are related by the compliance coefficients. For the hole drilling method in the isotropic materials, the compliance coefficients are calculated from the analytical solutions, and available in the ASTM standard. But for the orthotropic multilayered components typically found in microelectronics assemblies, numerical solutions are necessary. We developed a subroutine in ANSYS APDL to calculate the compliance coefficients of the hole drilling test in the molded and embedded power electronics components. This can extend the capability of the hole drilling method to determine residual stresses in more complex layered structures found in electronics.
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| 15. |
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| 16. |
- Andersson, Birgitta, et al.
(författare)
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Long-term charge retention on PWBs
- 2005
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Ingår i: Journal of Electrostatics. - : Elsevier BV. - 0304-3886 .- 1873-5738. ; 63:6-10, s. 597-602
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Tidskriftsartikel (refereegranskat)abstract
- A sample of printed wiring boards, isolated from ground, has been charged tribo-electrically and the charge decay process has been studied with focus on the long-term charge decay behaviour. It was found that the time constant 1/e did not say much about the proceeding decay process. Instead a second-order approximation model for the measured decay curves has been suggested.
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| 17. |
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| 18. |
- Andersson, Dag, et al.
(författare)
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COSIVU - Compact, smart and reliable drive unit for fully electric vehicles
- 2016
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Ingår i: 2016 Pan Pacific Microelectronics Symposium (Pan Pacific). - : Institute of Electrical and Electronics Engineers Inc.. - 9780988887398
-
Konferensbidrag (refereegranskat)abstract
- COSIVU is a three year collaborative research project that ended in September 2015 and which has been funded within the European Green Car Initiative (now the European Green Vehicle Initiative). COSIVU addresses one of the most critical technical parts in fully electrical vehicles (FEV) besides the energy storage system: the mechatronic drive-train unit. The COSIVU project has delivered a new system architecture for multiple wheel drive-trains by a smart, compact and durable single-wheel drive unit with integrated electric motor, full silicon carbide (SiC) power electronics (switches and diodes), a novel control and health monitoring module with wireless communication, and an advanced ultra-compact cooling solution. DfR utilizing FEM simulations ensures first time right solutions. This paper presents the main results including the architecture of the drive train solution as well as the modular design of the inverter based on Inverter Building Blocks, one per phase. Performance tests are presented here for the first time for both the heavy duty commercial vehicle solution performed in a test rig by Volvo, and the tests of the COSIVU solution adapted to a passenger car done by Elaphe.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Andersson, Dag R., et al.
(författare)
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A molecular beam scattering apparatus for surface chemiluminescence studies. Preliminary results for emission of excited K atoms.
- 1989
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A molecular beam scattering apparatus has been constructed for the study of surface chemiluminescence, i.e. the emission of light during a molecule-surface reaction. The apparatus consists of a beam forming stage designed for molecular and atomic chlorine, and a scattering chamber. The scattering chamber houses the sample, an alkali evaporation source, and a rotatable flange which holds the detectors; (i) the imaging optics of the photon detector, (ii) a mass spectrometer detector and (iii) a charged particle collector. The performance of the apparatus is demonstrated for a beam of chlorine molecules impinging on continuously evaporated or freshly evaporated potassium films. Intensity versus chlorine exposure and angular intensity distributions are presented for the K(4p ->4s) atomic line emission of the K+Cl$_2$ surface chemiluminescence spectrum.
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| 25. |
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| 26. |
- Andersson, Dag, et al.
(författare)
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Smart access to small lot manufacturing for systems integration
- 2018
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Ingår i: 2018 Pan Pacific Microelectronics Symposium, Pan Pacific 2018. - 9781944543044 ; , s. 1-9
-
Konferensbidrag (refereegranskat)abstract
- The three year EU project SMARTER-SI that ends in January 2018 has tested a new concept for small lot manufacturing for SMEs which we call the Cooperative Foundry Model (CFM). During previous research, all RTOs have completed building blocks, i.e. components or parts of systems which are readily available and characterized by their high Technology Readiness Level (TRL). These building blocks are combined and integrated in so-called Application Experiments (AEs), thereby creating innovative Smart Systems that serve the SMEs' needs. Four pre defined AEs have been presented before [1] and in this paper, six additional AEs will be presented: i) a smart sensor for pneumatic combined clutch and brakes, ii) smart well plates for tissue engineering integrating continuous, non-invasive TEER iii) microclimate sensor for moisture applications, iv) LTCC-Si-Pressure Sensor, v) miniaturized capillary electrophoresis system for bio analysis, and vi) a MEMS sensor module for respiratory applications. Finally, a brief description of ongoing standardization efforts is presented.
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| 27. |
- Andersson, Dag, et al.
(författare)
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SMARTER-SI - Smart access to manufacturing for Systems Integration
- 2017
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Konferensbidrag (refereegranskat)abstract
- The three year EU project SMARTER-SI that started in February 2015 has developed and tested a new production platform for smart systems that offer SMEs and “mid-cap” companies help to manufacture small and medium volumes. The ultimate goal of this project is to test a new concept for small lot production, which we call the Cooperative Foundry Model (CFM). The CFM is tested by combining components or parts of systems (building blocks) already developed by the RTOs involved in the project in so-called Application Experiments (AEs), thereby creating innovative Smart Systems which serve SMEs' product needs. During the first two years, four predefined AEs have been developed that consist of i) a multi-parametric point of care testing (POCT) device, ii) a dew-point measurement system, iii) a CO2 measurement system, and iv) a portable device that can be used to screen water quality.
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| 28. |
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| 29. |
- Andersson, Eric, 1992, et al.
(författare)
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Nondestructive cleaning of the LaAlO3/SrTiO3 surface with ultraviolet light and ozone
- 2016
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Ingår i: Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics. - : American Vacuum Society. - 2166-2746 .- 2166-2754. ; 34:4
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of ultraviolet light produced ozone and irradiation (UV/ozone) cleaning on the surface properties and interface electrical properties of 4 unit cell (uc) LaAlO3/SrTiO3 samples is examined. A standard photolithography process is used to contaminate the samples which are then cleaned in UV/ozone. Atomic force microscopy measurements show that the photoresist contaminated samples can be cleaned efficiently using this method. The surface roughness of the cleaned samples is comparable to that of the as-grown samples. Furthermore, electrical transport measurements show that the mobility decreases and the sheet carrier density increases for the contaminated samples, which also display indications of an onset to the Kondo effect. By removing the contaminants with UV/ozone cleaning, the mobility and sheet carrier density can be partially restored toward the as-grown values. The mobility is increased by about two times from approximate to 1000 cm(2) V-1 s(-1) for the contaminated samples to approximate to 2000 cm(2) V-1 s(-1) for the ozone cleaned ones. (C) 2016 American Vacuum Society.
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| 30. |
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| 31. |
- Andersson, Hans, 1950-
(författare)
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"Androm till varnagel-" : det tidigmoderna Stockholms folkliga rättskultur i ett komparativt perspektiv
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The basic concept for my research is legal culture. Thus I do not confine my study to what has been labelled "historical criminology", but also include litigation in civil cases concerning economic conflicts. Though quantitative analysis is a necessary preliminary step, the focus of my interest lies in attitudes and values, mainly of the lower classes. The study of popular legal culture in Stockholm 1620-1720 is viewed in a comparative perspective with Chester and Bremen, two cities with legal systems belonging to the two main judicial traditions of Europe.At the basis of any theory of culture and cultural change should be the assumption that there is a relation between culture and the power structure in the society where that culture is situated. But power is not only the determinant of culture, legal culture also includes the way that power is structured, and the ways it is exercised. In the field of legal culture the main change with respect to power in the period I have examined is what has been labelled the judicial revolution. This concept is related to the process of the state taking control over legal system and establishing a monopoly of violence in society.Two main features may be discerned in the change of criminal pattern of Stockholm during the period 1620-1720. There is a distinct fall of the frequency of lethal violence and a rise of female criminality. In fact the early eighteenth century Stockholm is the only case known where more women than men are indicted and sentenced.The comparative study focuses on how the legal tradition coexists with different political and economic systems and with differences in the legal culture: values and attitudes concerning the law, especially the code of honour, which from a Swedish point of view seems to be a crucial element in the popular legal culture, the education and backgrund of the judges and lawyers as well as the participation of laymen in the legal system, the equality before law; the role of different kinds of argumentation in the legal discourse and finally the existence of popular sanctions outside the official system.The anglo-saxon system has maintained many arcaic and irrational elements, but on the other hand it has fostered a strong tradition of commersialization, pluralism and freedom to choose between different kind of courts, which may have aided the developement of a capitalistic economy. In Bremen the bürger-elite stayed in control of the political power, working for the autonomy of the city. But at the same time the city council gave place to a large number of judicially trained members and ranged itsef within the legal system of the empire.
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| 32. |
- Andersson, Karl-Magnus, et al.
(författare)
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Interspecific and host-related gene expression patterns in nematode-trapping fungi.
- 2014
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Nematode-trapping fungi are soil-living fungi that capture and kill nematodes using special hyphal structures called traps. They display a large diversity of trapping mechanisms and differ in their host preferences. To provide insights into the genetic basis for this variation, we compared the transcriptome expressed by three species of nematode-trapping fungi (Arthrobotrys oligospora, Monacrosporium cionopagum and Arthrobotrys dactyloides, which use adhesive nets, adhesive branches or constricting rings, respectively, to trap nematodes) during infection of two different plant-pathogenic nematode hosts (the root knot nematode Meloidogyne hapla and the sugar beet cyst nematode Heterodera schachtii).
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| 33. |
- Andersson, Karl-Magnus, et al.
(författare)
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Proteome of the nematode-trapping cells of the fungus Monacrosporium haptotylum.
- 2013
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 79:16, s. 4993-5004
-
Tidskriftsartikel (refereegranskat)abstract
- Many nematophagous fungi use morphological structures called traps to capture nematodes by adhesion or mechanically. To better understand the cellular functions of adhesive traps, the trap cell proteome of the fungus Monacrosporium haptotylum was characterized. The trap of M. haptotylum consists of a unicellular structure called knob that develops at the apex of a hyphae. Proteins extracted from knobs and mycelia were analyzed using SDS-PAGE and LC-MS/MS. The peptide sequences were matched against predicted gene models from the recently sequenced M. haptotylum genome. In total, 336 proteins were identified, with 54 being expressed at significantly higher levels in the knobs than in the mycelia. The upregulated knob proteins included peptidases, small secreted proteins with unknown function and putative cell surface adhesins containing carbohydrate-binding domains including the WSC domain. Phylogenetic analysis showed that all upregulated WSC domain proteins belonged to a large, expanded cluster of paralogs in M. haptotylum. Several peptidases and homologs to experimentally verified proteins in other pathogenic fungi were also upregulated in the knob proteome. Complementary profiling of gene expression at the transcriptome level showed poor correlation between the upregulation of knob proteins and their corresponding transcripts. We propose that the traps of M. haptotylum contain many of the proteins needed in the early stages of infection, and that the trap cells can tightly control the translation and degradation of these proteins to minimize the cost of protein synthesis.
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| 34. |
- Andersson, Mathias, et al.
(författare)
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Management Measures to Reduce Continuous Underwater Noise from Shipping
- 2023
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Rapport (refereegranskat)abstract
- Underwater radiated noise (URN) from commercial ships is a significant source of elevated noise levels in the oceans and can have a negative impact on marine wildlife. Noise from commercial shipping places additional stress on the oceans, but is one of the least studied environmental pollutants, and there is an urgent need to reduce the aggregate stress levels. Until recently, reduction of underwater noise has not been prioritised by ship designers, shipowners, or crews. Even within the field of marine management, noise has received limited interest. However, the International Maritime organization (IMO) has adopted global guidelines on URN reduction, which are currently being updated. Within the EU, the Marine Strategy Framework Directive (MSFD 2008/56/EC) Descriptor 11 criteria 11.2, now provides a framework for marine administrators to manage noise by establishing threshold values. Marine management focuses on the total noise load on the marine environment. Management entails several considerations before recommendations can be made. As a first step, interdisciplinary teams need to assess the aggregated noise levels and determine acceptable thresholds based on the local ecosystem, then assess which existing mandates and management tools can be used, and finally assess how effective these mandates have been in improving the environment. These activities must also be managed in a way that is acceptable to various relevant stakeholders, who would need to follow the decisions. The URN from a ship can be affected by the vessel’s design, either during its construction or during upgrades, and balances a trade-off against fuel efficiency. However, the URN can also depend on how the ship is operated. Regulating ship speed is one potential management tool, and its effectiveness needs to be assessed. Other management measures include how shipping lanes are drawn, areas to avoid, financial support, information, etc. This report focuses on possible policy measures that the Swedish authorities could adopt to lower URN by regulating the speed of ships. The report presents an interdisciplinary analysis, using a case study of an area in the southern Kattegat that covered several maritime zones, different national jurisdictions, intensive traffic, and high natural values. An important part of the work was to assess whether existing source models for ship noise could be used for the type of ships that are common in waters around Sweden. In this study, the JOMOPANS-ECHO (J-E) model was used.The J-E model was validated by comparing measurement data from a hydrophone station at Vinga on the Swedish coast that collected data from ships (254 passages) that used the port of Gothenburg. The analysis showed some deviation between the J-E model and measurement data, which could be due to differences in the length and speed of ships in waters around Sweden compared to the ships used in the development of the J-E model. However, this was likely to have negligible impact on the outcome of the case study.Analyses of ship traffic in 2021 showed that 4,511 unique vessels visited the study area at least once. Most ships followed the main routes, but no part of the study area was completely free from ship traffic. About 68% of the ships visited the study area for 1-4 days, while about 32% visited the area more regularly. The most common ship types were General Cargo Ships, Dry Bulk Ships, and Tankers. The ships that on average travelled at highest speeds were RoPax Ships, RoRo Ships, Vehicle Carriers, and Container Ships. The ships were registered in 64 countries. About two percent of the ships were registered in Sweden and about four percent in Denmark.Legal analysis showed that Sweden has the right and the responsibility to take measures to reduce underwater noise from ships to the extent that the noise can be deemed to pollute the marine environment. However, this mainly applies to Sweden’s territorial seas, which cover roughly half the area being studied for this report. In the portion that constitutes Danish territorial sea, Denmark has comparable opportunities for managing URN. In areas that are Swedish or Danish exclusive economic zones (EEZs), the ability to introduce mandatory speed limits is significantly limited. There, the most realistic option would be to request the IMO to establish speed limits, or alternatively to issue a recommendation to navigate at lower speeds, although such guidance could not be enforced on ships that do not voluntarily reduce their speed.It was estimated that lowering the ships' speeds to a hypothetical limit of 11 kn would reduce the average URN levels by 4.4 ± 2 dB, as registered by local receivers in the study area. This speed limit would affect approximately 44% of the ships in the area. A maximum speed of 13 kn would instead reduce the level by 1.9 ± 0.5 dB and would affect 11% of the ships on average. The reduction in noise levels may temporarily be much higher in the immediate vicinity of individual fast ships, and there might be a high degree of variation between different ships.The study and report make it clear that it is a complex task to assess the feasibility and benefit of introducing a specific marine management tool, in this case an enforceable local speed limit. But it is also clear that there are reliable methods to make the preliminary assessments, and that it requires interdisciplinary analyses and competence.
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| 35. |
- Andersson, Pontus, 1971, et al.
(författare)
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Isobar Selective Laser Photodetachment In Trace Element Analysis
- 2009
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Ingår i: AIP Conference Proceedings. ; 1104
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Konferensbidrag (refereegranskat)abstract
- We are investigating the possibility to use laser photodetachment of negative ions as an isobaric selective filter in accelerator mass spectrometry (AMS). If successful, this method can be used to obtain higher sensitivity realized through better selectivity by suppression of molecular and/or elemental isobaric interference in different investigations using ultra rare isotopes in the 10−13 range and below.
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| 36. |
- Andersson, Pontus, 1971, et al.
(författare)
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Nearly complete isobar suppression by photodetachment
- 2010
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 1089-7550 .- 0021-8979. ; 107:2
-
Tidskriftsartikel (refereegranskat)abstract
- The efficiency of selective suppression of negative ions by photodetachment in a gas-filled radio frequency quadrupole ion cooler was investigated with a new detection method. A neodymium doped yttrium aluminum garnet laser beam at 1064 nm was used to remove Co− ions in the radio frequency quadrupole cooler and the remaining ions were then probed by photodetachment and neutral particle detection. More than 99.99% suppression of the Co− ions was observed. Under identical conditions, only 20% of a Ni− beam was suppressed. The results demonstrate that this isobar suppression technique can lead to nearly complete elimination of certain isobaric contaminants in negative ion beams, opening up new experimental possibilities in nuclear and atomic research and accelerator mass spectrometry.
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| 37. |
- Andersson, Pontus, 1971, et al.
(författare)
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Observation of the 2S1/2 metastable state in Pt−
- 2009
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Ingår i: PHYSICAL REVIEW A. - 1050-2947. ; 79, s. 022502 -
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Tidskriftsartikel (refereegranskat)abstract
- We have experimentally investigated the structure of the Pt− ion using laser photodetachment threshold spectroscopy. The experiment was conducted using a collinear laser-ion beam apparatus, in which the residual atoms created in the photodetachment process were detected. A p-wave threshold was observed in the photo- detachment spectrum at an energy of 6851͑13͒ cm−1. We conclude that this onset originates from a photode- tachment transition in which the initial state of Pt− is the previously unobserved 5d106s 2S1/2 state and the final state of Pt is the 5d96s 3D3 ground state. The excitation energy of the 2S1/2 state is determined to be 10 289͑13͒ cm−1. This value can be compared with a multiconfiguration Dirac-Fock calculation performed by Thøgersen et al. ͓Phys. Rev. Lett. 76, 2870 ͑1996͔͒, which yielded an excitation energy of 11 301 cm−1. Our data show no indication of the presence of any other state of Pt−. We conclude that the structure of the Pt− ion is now fully known.
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| 38. |
- Andersson, Pontus, 1971, et al.
(författare)
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Radiative lifetimes of metastable states of negative ions
- 2006
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622 .- 2469-9926 .- 2469-9934. ; 73, s. 032705-
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Tidskriftsartikel (refereegranskat)abstract
- We present a technique for measuring the radiative lifetimes of metastable states of negative ions that involves the use of a heavy-ion storage ring. The method has been applied to investigate the radiative decay of the np(3) P-2(1/2) levels of Te-(n=5) and Se-(n=4) and the 3p(3) D-2 state of Si- for which the J=3/2 and 5/2 levels were unresolved. All of these states are metastable and decay primarily by emission of E2 and M1 radiation. Multi Configuration Dirac-Hartree-Fock calculations of rates for the transitions in Te- and Se- yielded lifetimes of 0.45 s and 4.7 s, respectively. The measured values agree well with these predicted values. In the case of the D-2 state of Si-, however, our measurement was only able to set a lower limit on the lifetime. The upper limit of the lifetime that can be measured with our apparatus is set by how long the ions can be stored in the ring, a limit determined by the rate of collisional detachment. Our lower limit of 1 min for the lifetime of the D-2 state is consistent with both the calculated lifetimes of 162 s for the D-2(3/2) level and 27.3 h for the D-2(5/2) level reported by O'Malley and Beck and 14.5 h and 12.5 h, respectively, from our Breit-Pauli calculations.
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| 39. |
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| 40. |
- Andersson, Pontus, 1971, et al.
(författare)
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The electron affinity of phosphorus
- 2007
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Ingår i: Journal of Physics B-Atomic Molecular and Optical Physics. ; 40:20, s. 4097-4107
-
Tidskriftsartikel (refereegranskat)
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| 41. |
- Andersson, Susanne, et al.
(författare)
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From glass ceiling to firewalls : Detecting and changing gendered organizational norms
- 2022
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Ingår i: NORA. - : Routledge. - 0803-8740 .- 1502-394X. ; 30:2, s. 140-153
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Tidskriftsartikel (refereegranskat)abstract
- This article is based on an empirical case study with an interactive research approach focusing on gendered norms in a Swedish truck Company. It discusses the combined value of using the metaphor of a firewall for (1) analysing how organizational constraining gendered norms are done in everyday organizational life, and (2) as a practical tool to facilitate the processes aimed at improving norm awareness. The metaphor embodies an understanding that makes it possible to visualize relational ongoing organizational processes and power dimensions. In addition, the firewall is useful for emphasizing variations and complexity. Variations and dynamics are manifested in the ways that employees need to fulfil varying “codes” in order to be accepted. The possession of certain codes (norms) that are required to pass through the first layer of the firewall (employment), and give access to some networks, does not automatically ensure acceptance and integration into more influential networks (referred to as the informal and inner layers of the firewall). The results furthermore show that the firewall metaphor is fruitful when facilitating reflection processes amongst employees to improve norma wareness and to discuss strategies for change. The conclusion is that the firewall metaphor facilitates an analysis of the relational and complex doing of constraining norms, and that it also can be used to initiate change.
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| 42. |
- Andersson, Susanne, et al.
(författare)
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Moving with(in) normative firewalls : a dynamic approach to study gendered careers and innovation processes in the truck industry
- 2018
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Konferensbidrag (refereegranskat)abstract
- In this paper we explore how existing work place culture and gendered norms impact on the possibilities to work with so called ”norm-critical” innovation processes in an organisation. Norm-critical reflexivity in the context of innovation processes implies to pay attention to invisible and implicit norms that may result in that certain privileged perspectives is being prevailed (over others) (Balkmar & Lykke 2015). The empirical findings emanates from a two year interactive research project, in which gender researchers in collaboration with participants at Volvo Group, Sweden, have explored the ways that the company can increase its capacity to work with norm-critical perspectives in the innovation process. Volvo is a highly gender segregated organisation. At the same time the trucking industry in itself is highly masculinized in terms of different professions; ranging from truck drivers to sales personnel to technical engineers involved in the design and manufacturing of trucks. In later years the shortage of truck drivers, in combination with more women drivers entering trucking academies and haulage contractors, has led to a questioning of male norms in the transport business. This includes reports of difficult working conditions for female truckers, including how the design of the truck itself takes the male body as the implicit norm, to the assumption that it is a man that is the presumed driver of trucks.This paper focus on the part of the project that seeks to better understand how existing work-place culture and norms structure who is considered the ideal employee (Acker 1992) and its implications for innovation. This includes studying its impacts on both the possibility for different categories of employees to take part in the innovation work on equal terms, and the ability to reflect upon the impact of implicit norms in the innovation process itself. In total, 17 semi-structured interviews were conducted with co-workers and managers (13 women and 5 men). The main questions concerned whether there existed ideals that formed implicit ”codes” (Bendl and Schmidt 2010) in the organization and its impact on ideas of preferred professional qualifications, behaviors, personal qualities and its links to career possibilities and innovation. The underlying theoretical assumption is that gender is a fundamental element of organisational structure and work life; “present in [its] processes, practices, images and ideologies, and distribution of power” (Acker 1992, p. 567). The way that gender plays out in the daily life in a workplace is understood as not being a static barrier prohibiting women in general, rather, it is considered fluid, relational and may vary depending on the context (Meyerson & Fletcher 2001, Bendl and Schmidt 2010). It is argued that the concept ”fire wall” (Bendl and Schmidt 2010 ), offers a fruitful way to highlight the elasticity and permeability that we believe characterize the forms of discrimination, inclusion and exclusion that takes place in these processes.ReferencesAcker, J. 1992. Gendering Organisational Theory. In Mills, A. and Tancered, P. (eds.). Gendering Organisational Analysis. London: SAGE.Acker, J. 2006. Inequality Regimes: Gender, Class, and Race in Organisations. Gender and Society 20(4):441-464.Balkmar, D. & Lykke, N. 2015. Developing disruptive norm-critical innovation at Volvo: FINAL REPORT. Linköping: Tema Genus Report Series No. 23: 2015.Bendl, R. & Schmidt. 2012. From 'Glass Ceilings' to 'Firewalls' - Different Metaphors for Describing Discrimination. Gender, Work and Organization. Vol. 17. No 5:612-635.Meyerson, D. & Fletcher J.K. 2001. A Modest Manifesto for Shattering the Glass Ceiling. Boston: Harvard Business Review.
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| 43. |
- Andersson, Åsa, et al.
(författare)
-
Översyn av förordning om miljökvalitetsnormer för fisk- och musselvatten : Redovisning av regeringsuppdrag med Havs- och vattenmyndighetens analys av normerna och förslag till ändrad lagstiftning
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Regeringen gav genom ett beslut den 22 oktober 2015 Havs- och vattenmyndigheten i uppdrag att göra en översyn av förordningen (2001:554) om miljökvalitetsnormer för fisk- och musselvatten (fisk- och musselvattenförordningen). Behovet av att göra denna översyn har framförts av Havs- och vattenmyndigheten, Naturvårdsverket och Länsstyrelsen i Västra Götalands län. I rapporten görs en översyn av miljökvalitetsnormerna i förordningen (2001:554) om miljökvalitetsnormer för fisk- och musselvatten och en bedömning av om det finns normer som bör ändras, tas bort eller om samma skyddsnivå kan uppnås på annat sätt. Havs- och vattenmyndigheten föreslår att fisk- och musselvattenförordningen upphävs. Som en följd av detta behöver ett antal föreskrifter upphävas eller ändras. Därutöver behöver viss vägledning tas fram för att täcka återstående skyddsbehov.Det är svårt att få en överblick av i vilken utsträckning fisk- och musselvattenförordningen har påverkat den övervakning som bedrivs och hur mycket övervakning som bedrivs enbart utifrån förordningens krav. Havs- och vattenmyndighetens bedömning är dock att ett upphävande av förordningen inte kommer att påverka den övervakning som utförs på ett betydande sätt. Konsekvensutredningen visar att fisk- och musselvattenförordningen kan upphävas och att detta medför i huvudsak positiva effekter för såväl miljön som berörda myndigheter och verksamhetsutövare.
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| 44. |
- Andrae, Anders, 1973, et al.
(författare)
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Application of Simplified Methods for Partial Environmental Assessment of Microelectronics Soldering Materials and Processes in Small and Medium Sized Enterprises
- 2005
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Ingår i: International Journal of Life Cycle Assessment. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- As a consequence of the environmental regulations becoming stricter for companies within the microelectronics business area, alternative materials and processes with lower environmental performance will have to come in use. These new materials and processes should be process validated, and environmentally assessed. The Swedish microelectronics manufacturers do not use environmental assessment tools to determine if one alternative is "greener" than the other, as they have neither time nor legislative pressure. Instead, they refer to ´lists´ regarding limitations in the use of forbidden chemicals, and compare the ´lists´ with material safety data sheets. IVF in Sweden had the task of co-ordinating a governmentally financed project of which one of the goals was to advise producers, of microelectronics, on how to compare different material/process alternatives when introducing Pb-free soldering manufacturing technology. The scope of this paper is the evaluation of simplified and partial environmental assessment methods for microelectronics soldering. The problem addressed was the identified scarce understanding and under-use of environmental assessment methodologies in the small and medium sized enterprises in the Swedish electronics industry. A subtask was to analyse if it would be possible to perform a useful evaluation in one working day.A literature study revealed that several methods exist for environmental assessment, but most of them were assessed to be too complicated for the purpose of the present study. Two methods were introduced in the project; a qualitative Checklist Method (CM), and the quantitative Toxic Potential Indicator (TPI) that was used as a screening approach. The methods were tested at a microelectronics manufacturer to find out the applicability and the easiness of use. The checklist was applied to two wave soldering concepts and the TPI was applied to two Sn-Pb solder pastes and two Pb-free solder pastes. The CM generates information that can be used in the identification of qualitative environmental aspects, and the TPI provides fast but coarse results. It was possible for the company to perform this limited environmental assessment in one working day, as the amount of available input information is fairly limited. The participating microelectronics manufacturers in this study have confirmed this. The companies will use fast, understandable and rapidly introducible methods. The TPI was easy to use practically, but the input data available was regarded as too rough to distinguish among similar solder pastes. Anyway, by using the methods described in this paper, it would be possible to perform the assessment in one working day. It was perceived as worthwhile for the CM, and also to some degree for the TPI, despite data gaps for flux constituents. It is recommended that the flux constituents of solder pastes are risk evaluated to provide data for indicator tools like the TPI. The CM and the TPI should also be evaluated in industry sectors other than the microelectronics sector. This is needed to generally answer whether there are useful and systematic methods of environmental risk evaluation in product development. In a broader view, it should be researched what barriers are hindering small and medium sized enterprises to invest more in design for environment.
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| 45. |
- Andrae, Anders, 1973, et al.
(författare)
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Significance of intermediate production processes in life cycle assessment of electronic products assessed using a generic compact model
- 2005
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Ingår i: Journal of Cleaner Production. ; 13:13-14, s. 1269-1279
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper a generic model for life cycle inventory (LCI) data collection is presented and applied to a product system of a digital system telephone (DST). It is also shown that intermediate unit processes (IUPs) are of global warming importance. Compared to earlier efforts in the field of environmental life-cycle assessment of electronic products, the developed model enables a more partitioned LCA result, with respect to both components and processes. In our model the components are first divided into main groups and then into sub-groups. This division results in process modules for unit processes, some of which are similar for the ingoing components, thus reducing the computational effort. The model is demonstrated for a cradle-to-gate calculation focusing on greenhouse gas emissions. Using scenario analysis for integrated circuits and printed wiring boards, the possible contribution from IUPs was analysed.
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| 46. |
- Balkmar, Dag, 1974-, et al.
(författare)
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Women truck drivers and (future) mobile work : Towards gender equal transport futures?
- 2021
-
Ingår i: Gender and Equality in Transport. - Dublin : TU Dublin. ; , s. 161-165
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper focuses gender and gender equality in contemporary and future haulage business, arguing for a need for norm-critical approaches to build more gender equal transport futures. Currently, there is a general demand for more drivers internationally and in Sweden. Following the current driver shortage in occupational road freight, transport companies in Europe and Sweden recognise the need to recruit more women chauffeurs. Part of the problem is how transport is gendered, strongly intertwined with masculine norms that prevents nonnormative bodies to identify themselves as drivers. In Sweden, a country with a world reputation as champions in gender equality, men still make up more than 90 % of the work force in the Swedish transport business. While recruiting more women would contribute to solve the urgent problem of driver shortage, women drivers typically face gendered problems, concerning their personal safety, harassments, hygiene, and work/life (im)balance. From the perspective of the haulage business, addressing these gendered problems can increase the ability hire more women drivers, but would also need to develop transport innovations that suit not only today’s male users but also those of tomorrow.Future road freight and transport innovations such as more autonomous vehicles are often imagined to ‘solve’ some of the current problems that transport companies struggle with, including driver shortage. With the advent of autonomous, electrified and connected mobilities, we may anticipate both a gendered re-segregation and that fewer drivers would be needed (Balkmar and Mellström 2018). Nevertheless, problems of road transportation and the lack of gender equality in the haulage business can’t be solved following the “old logics of a technological fix”, gendered social and cultural issues need to be part of the solution (Kröger and Weber, 2018). Against this background, the aim of this paper is to explore how normcritical perspectives can offer ways forward with regards to gender and (lack of) gender equality in the haulage business. This includes to consider how technological innovations may change what it entails to be a truck driver and open new opportunities for the profession with regards to gender equality.
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| 47. |
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| 48. |
- Bergsjö, Dag Henrik, 1980, et al.
(författare)
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Industrial Scale Production of Customized Ceramic Prostheses
- 2014
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Ingår i: Advanced Ceramics for Dentistry, 1st Edition. ; , s. 416-
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Today, there are many solutions for dental rehabilitation. A damaged tooth can be replaced with a dental crown, and a toothless patient can be rehabilitated with implants and a corresponding bridge set-up. Traditionally, a dental crown is manufactured by veneering porcelain to a metal surface that is obtained through the use of casting principles. Implant rehabilitations used to rely on a high degree of handcraft by the dentist, where freehand drilling into the jaw- bone was supported by X-ray pictures and was done before implant insertion. Crown and implant rehabilitations can be provided at a much higher degree of industrialization by means of mass customization. The most common dental rehabilitations are crown restorations for single teeth, while full arch implant rehabilitations are the most comprehensive treatments. Trends in industry lean toward a higher degree of automation in production and manufacturing where key characteristics of a well-functioning ceramic prosthesis are cost reduction, patient satisfaction, and quality in both function and perception.
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| 49. |
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| 50. |
- Björling, Thomas, 1976-
(författare)
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Synthesis and characterisation of Zintl hydrides
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The synthesis, structural characterisation and the properties of the Zintl hydrides AeE2H2 and AeAlSiH (Ae = Ba, Ca, Sr; E = Al, Ga, In, Si, Zn) are reported. The first hydride in this class of compounds is SrAl2H2 which was discovered under an experiment by Gingl, who hydrogenated SrAl2 at various temperatures. (Gingl et al, Journal of Alloys and Compounds 306 (2000) 127-132). The intention was to form alanates, e.g. AlH4-, by terminating the three dimensional four connected aluminium network in SrAl2. The new hydride, SrAl2H2, has a partially conserved aluminium network. The three dimensional anionic network in SrAl2 is reduced to two dimensions in the hydride, with aluminium bonded to both aluminium and hydrogen. This type of bonding configuration has not been observed before.The hydrogenation of SrAl2 is straight forward, 190 oC and 50 bar, compared to the difficult synthesis of alanates and alane, AlH3. The latter synthesises uses aluminium in its zero oxidation state in contrast to the synthesis of SrAl2H2 from SrAl2. (In the SrAl2-precursor aluminium is reduced by the electropositive metal to -I.) Thus, the discovery shows a different route to alanates by using precursors with aluminium in a reduced state. If SrAl2H2 is further hydrogenated at 250 oC the two dimensional network breaks and Sr2AlH7 forms.We wanted to investigate if SrAl2H2 was a singularity or if other similar compounds exist. We wanted to study how hydrogenation of precursors similar to the aluminide result in 1) new routes to compounds with high hydrogen content, as alanates, 2) to investigate how the E-H bond is affected as function of the network composition among different ternary hydrides, in particular BaAlxSi2-xHx, and choice of active metal.BaGa2H2 and SrGa2H2, two hydrides isostructural with SrAl2H2, were synthesized from its precursors BaGa2 and SrGa2. In addition three ternary hydrides BaAlSiH, CaAlSiH and SrAlSiH were manufactured from their related AeAlSi precursors.All powders were characterized by neutron and x-ray diffraction methods.An increased stability towards water/moisture compared to ordinary saline hydrides was noticed, especially for the ternary hydrides. Heat stability was measured with DSC (differential scanning calorimetry). The hydrides BaGa2H2 and SrGa2H2 decompose around 300 oC at 1 atm. This is similar to isostructural SrAl2H2. The ternary hydrides BaAlSiH and SrAlSiH decompose at 600 oC, at 1 atm, which is the highest noticed temperature for compounds with Al-H bonds. Inelastic neutron scattering experiments showed that these hydrides Al-H and Sr-H bonds are really weak, even weaker then the Al-H interactions in alanates and alanes. These hydrides are probably stabilized be their lattices. The electric properties among the ternary hydrides were measured with IR-spectroscopy (diffuse reflectance). The ternary hydrides, AeAlSiH, are indirect semi conductors. BaGa2H2 and SrGa2H2 are conductors. The ternary hydrides, AeAlxSi2-xHx, may have adjustable band gaps, which we were not able to determine.This work is leading into a new research area within the field of metal hydrides.
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