Undersökning av potentiella protonledare genom dopning av BaTiO3 och SrTiO3 med Fe och Al

There are many interesting applications of proton conducting oxides, such as electrolytes in fuel cells, hydrogen sensors and catalytic membranes for hydrogenation or dehydrogenation of organic compounds. Previous work explored doping BaTiO3 with the Rare Earth Element (REE) Sc to introduce oxygen vacancies in the structure, making it a Proton Conductor (PC). PC oxides are often perovskite materials, ABX3, wherethe A- or B-site are doped in such a way that less oxygen can be contained, creating oxygen vacancies. When these materials are then hydrated so that water molecules occupy the vacancies, hydrogen is essentially added to the system in the form of protons. This study expanded on those results, exploring possible dopants that are non-REEs, theoretically improving availability and cost. Fe and Al were chosen as B-site dopants and Sr was included as an alternative to Ba as the A-site cation, compensating for the smaller size of the Fe- and Al atoms compared to Ti. Solid state synthesis was used to manufacture the different compounds and then X-Ray Diffraction (XRD), ThermoGravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) were used inorder to investigate their properties. The main focus was to explore ift he materials could be synthesised using this method, their structures and how they reacted to hydration. All Al doped samples could not be made phase pure with the synthesis parameters used. BaTi0.5Fe0.5Oy was stabilised by the inclusion of Ti, as it did not decompose during hydration, unlike pure BaFeOx. Significant hydration was achieved in a wet nitrogen atmosphere at 185°C, but its structure type was hexagonal, which is known to be unfavourable for proton conduction. SrTi0.5Fe0.5Oy had a cubic structure which is a beneficial structural trait for proton conduction, but negligible hydration was observed by TGA. A small increase in cell volume indicates that it might still have taken up some water, but the methods used for hydration were not optimal for this material. The oxygen content of the materials was not determined in this project and methods such as Mössbauer spectroscopy and iodometric titration should be included in any related future studies

Undersökning av potentiella protonledare genom dopning av BaTiO3 och SrTiO3 med Fe och Al

There are many interesting applications of proton conducting oxides, such as electrolytes in fuel cells, hydrogen sensors and catalytic membranes for hydrogenation or dehydrogenation of organic compounds. Previous work explored doping BaTiO3 with the Rare Earth Element (REE) Sc to introduce oxygen vacancies in the structure, making it a Proton Conductor (PC). PC oxides are often perovskite materials, ABX3, wherethe A- or B-site are doped in such a way that less oxygen can be contained, creating oxygen vacancies. When these materials are then hydrated so that water molecules occupy the vacancies, hydrogen is essentially added to the system in the form of protons. This study expanded on those results, exploring possible dopants that are non-REEs, theoretically improving availability and cost. Fe and Al were chosen as B-site dopants and Sr was included as an alternative to Ba as the A-site cation, compensating for the smaller size of the Fe- and Al atoms compared to Ti. Solid state synthesis was used to manufacture the different compounds and then X-Ray Diffraction (XRD), ThermoGravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) were used inorder to investigate their properties. The main focus was to explore ift he materials could be synthesised using this method, their structures and how they reacted to hydration. All Al doped samples could not be made phase pure with the synthesis parameters used. BaTi0.5Fe0.5Oy was stabilised by the inclusion of Ti, as it did not decompose during hydration, unlike pure BaFeOx. Significant hydration was achieved in a wet nitrogen atmosphere at 185°C, but its structure type was hexagonal, which is known to be unfavourable for proton conduction. SrTi0.5Fe0.5Oy had a cubic structure which is a beneficial structural trait for proton conduction, but negligible hydration was observed by TGA. A small increase in cell volume indicates that it might still have taken up some water, but the methods used for hydration were not optimal for this material. The oxygen content of the materials was not determined in this project and methods such as Mössbauer spectroscopy and iodometric titration should be included in any related future studies

Why should I move to Sweden? : A study about place branding, regional identity and stereotypes in northern Sweden

This study is a rhetorical analysis of how three sparsely populated regions in Norrland –Region Västerbotten, Region Norrbotten and Region Jämtland Härjedalen – communicate on YouTube to strengthen their place branding, create a strong regional identity and attract new residents. By analyzing the content of the videos in relation to stereotypes about Norrland, the study aims to gain insight into how these regions communicate, and how the communication affects the image of Norrland. The study contributes to understandings of how regions communicate to create a positive image of themselves and attract newcomers. The results show that common themes emphasized in the videos are the regions unique and beautiful nature, well developed healthcare, technological innovation, hope for the future and a sense of community between the residents in the region. The findings also indicate that regions mostly use ethos and pathos in their videos to appeal to viewers emotions and establish credibility

Why should I move to Sweden? : A study about place branding, regional identity and stereotypes in northern Sweden

This study is a rhetorical analysis of how three sparsely populated regions in Norrland –Region Västerbotten, Region Norrbotten and Region Jämtland Härjedalen – communicate on YouTube to strengthen their place branding, create a strong regional identity and attract new residents. By analyzing the content of the videos in relation to stereotypes about Norrland, the study aims to gain insight into how these regions communicate, and how the communication affects the image of Norrland. The study contributes to understandings of how regions communicate to create a positive image of themselves and attract newcomers. The results show that common themes emphasized in the videos are the regions unique and beautiful nature, well developed healthcare, technological innovation, hope for the future and a sense of community between the residents in the region. The findings also indicate that regions mostly use ethos and pathos in their videos to appeal to viewers emotions and establish credibility

Tuning in-plane magnetic anisotropy and temperature stability in amorphous trilayers

Better understanding of the nature of magnetic coupling in soft/hard nanocomposites paves the way for tailored exchange-spring magnets. We have investigated a series of amorphous magnetic thin films and trilayers of magnetically soft Co85(Al70Zr30)15 and magnetically hard Sm12Co81Ti7, produced with DC magnetron sputtering. The overall magnetic properties of the trilayers were investigated with focus on the effects of layer configuration and thicknesses on coercivity, originating from the Sm12Co81Ti7 phase, and uniaxial in-plane anisotropy induced from the Co85(Al70Zr30)15 phase. In addition, we found that the thermal stability of a 20 nm Sm12Co81Ti7 layer was significantly increased if surrounded by two 10 nm Co85(Al70Zr30)15 layers in a trilayer structure.De två första författarna delar förstaförfattarskapet.</p

Crack reduction in laser powder bed fusion of MnAl(C) using graphene oxide coated powders

MnAl(C) is a promising candidate as a rare earth free magnet. When processing MnAl(C) in laser powder bed fusion (L-PBF) the high cooling rates can retain the high temperature epsilon-phase which can then be annealed at low temperatures to yield the ferromagnetic tau-phase. However, MnAl(C) has been shown to be difficult to print using L-PBF and the material is prone to severe cracking. In this study, we have investigated how the addition of a graphene oxide (GO) coating on the powders can affect the processability of MnAl(C) and properties of the printed parts. MnAl(C) powders were coated with 0.2 wt.% GO using a wet-chemical process. The addition of GO reduced crack formation in the printed parts, and also influenced the degree of &lt; 001 &gt; texture along the build direction. After printing, densities of 93% and 87% could be achieved for the reference and 0.2 wt.% GO, respectively. Furthermore, a 35% reduction of cracking was calculated from image analysis, comparing printed samples produced from coated and non-coated powders. Both powders formed mostly the e-phase but some two-phase regions with a mix of γ- and ε-phase could be observed in the as-printed parts, but seemed to be more prominent in the uncoated reference samples and could also be linked to cracks. The τ-phase together with smaller amounts of secondary phases was obtained after heat treatment at 560 degrees C for 5 min for both samples. Vibrating sample magnetometry was used to measure the magnetic properties, the reference had a remanence of 33Am2/ kg and a coercivity of 139 kA/m, and the 0.2 wt.% GO sample showed a similar remanence of 30Am2/ kg and coercivity of 130 kA/m. These results show that GO coating is a viable method to reduce detrimental cracking in L-PBF MnAl without reducing the magnetic performance of the material

3D-modellering och flödessimulering för additiv tillverkning av medicintekniskt munstycke för oral kryoterapi inom onkologisk vård

Oral mucositis is an inflammation that affects the mucosa in the mouth. It often affects patients undergoing chemotherapy for cancer. The risk of inflammation can be reduced by cooling the mouth. In this project, ten different mouthpieces for cryotherapy of the oral cavity with air as cooling medium have been modeled in the SolidWorks. Flow simulations have been made on the different mouthpieces to investigate how the air is distributed in the models. The goal of the simulations is that the outflow of air should not differ more than 10 % between the largest and the smallest flow. With the results, the mouthpieces could be fine-tuned. Flow simulation on the ten prototypes gave varying results, some have a good distribution of air between the holes. Some, however, do not evenly spread the air and it flows much less air through certain holes. Three prototypes were printed in hard plastic at an early stage to see how they fit the mouth. At the end of the project, a total of seven models were printed by TADA medical's partner in a softer plastic. Several models then showed some points that need to be considered when designing nozzles. A handful of the models have been tested with the cooling device and the flow has been examined with a heating camera. The other prototypes have not been 3D-printed, so there is nothing about their convenience. To get better results, more advanced simulation requires the environment of the oral cavity with the exact dimensions

Stress related magnetic imaging of iron-based metallic glass produced with laser beam powder bed fusion

Additive manufacturing makes the production of bulk metallic glasses possible in thicknesses exceeding the critical casting thickness. However, a crucial challenge is the build-up of thermally induced stress, often resulting in printed parts suffering from cracking. In this study, the process parameters are optimised for printing soft-magnetic metallic glass samples of an Fe-based alloy (Fe73.8P10.6Mo4.2B2.3Si2.3C6.7), using laser beam powder bed fusion. In addition, the structural and magnetic properties of as-received and heat-treated powder are investigated and compared to those of the printed samples. Kerr microscopy is used for imaging the magnetic domains on single track cross-sections produced on top of a polished printed sample. This reveals the shape of the melt pool of a single laser track, as well as the magnetic domains around it and in other regions of the printed sample. The shape and size of the magnetic domains reflect the residual stress in the sample through the effect of magneto-elastic coupling. This magnetic contrast could be used to get further insights into how to control the development of stress during the printing process.De två första författarna delar förstaförfattarskapet</p

Achieving low elastic moduli of bcc Ti-V alloys in vicinity of mechanical instability

Body centered cubic (bcc) Ti-based alloys are of interest for multiple technological applications ranging from aerospace technology to biomedicine. However, these alloys are usually unstable at low temperatures. Indeed, the calculated elastic modulus C ' of bcc Ti-V alloys with low V concentrations is negative at 0 K temperature, indicating their mechanical instability. Here, we investigate elastic moduli of the Ti-V system in the vicinity of mechanical instability theoretically and experimentally. Our calculations predict that mechanical stabilization of bcc Ti-V alloys, which is governed by the hardening of C ', is possible at as low V concentration as 18 at.%. We synthesize single-phase bcc alloys with as little as 22 at.% of V with low values of Young's modulus. Moreover, we predict strong concentration dependence of anisotropy of Young's modulus in these alloys that can also be used in tuning the alloy composition to design materials for specific applications

In Situ Mapping of Phase Evolutions in Rapidly Heated Zr-Based Bulk Metallic Glass with Oxygen Impurities

Metallic glasses exhibit unique mechanical properties. For metallic glass composites (MGC), composed of dispersed nanocrystalline phases in an amorphous matrix, these properties can be enhanced or deteriorated depending on the volume fraction and size distribution of the crystalline phases. Understanding the evolution of crystalline phases during devitrification of bulk metallic glasses upon heating is key to realizing the production of these composites. Here, results are presented from a combination of in situ small- and wide-angle X-ray scattering (SAXS and WAXS) measurements during heating of Zr-based metallic glass samples at rates ranging from 102 to 104 Ks−1 with a time resolution of 4ms. By combining a detailed analysis of scattering experiments with numerical simulations, for the first time, it is shown how the amount of oxygen impurities in the samples influences the early stages of devitrification and changes the dominant nucleation mechanism from homogeneous to heterogeneous. During melting, the oxygen rich phase becomes the dominant crystalline phase whereas the main phases dissolve. The approach used in this study is well suited for investigation of rapid phase evolution during devitrification, which is important for the development of MGC