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- Niarchos, D., et al.
(author)
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Toward Rare-Earth-Free Permanent Magnets : A Combinatorial Approach Exploiting the Possibilities of Modeling, Shape Anisotropy in Elongated Nanoparticles, and Combinatorial Thin-Film Approach
- 2015
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In: JOM. - : Springer Science and Business Media LLC. - 1047-4838 .- 1543-1851. ; 67:6, s. 1318-1328
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Journal article (peer-reviewed)abstract
- The objective of the rare-earth free permanent magnets (REFREEPM) project is to develop a new generation of high-performance permanent magnets (PMs) without rare earths. Our approach is based on modeling using a combinatorial approach together with micromagnetic modeling and the realization of the modeled systems (I) by using a novel production of high-aspect-ratio (> 5) nanostructrures (nanowires, nanorods, and nanoflakes) by exploiting the magnetic shape anisotropy of the constituents that can be produced via chemical nanosynthesis polyol process or electrodeposition, which can be consolidated with novel processes for a new generation of rare-earth free PMs with energy product in the range of 60 kJ/m(3) < (BH)max < 160 kJ/m(3) at room temperature, and (II) by using a high-throughput thin-film synthesis and high-throughput characterization approach to identify promising candidate materials that can be stabilized in a tetragonal or hexagonal structure by epitaxial growth on selected substrates, under various conditions of pressure, stoichiometry, and temperature. In this article, we report the progress so far in selected phases.
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| 2. |
- Azasu, S, et al.
(author)
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CDIO in Africa
- 2019
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In: <em>Proceedings of the 15th International CDIO Conference</em>.
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Conference paper (peer-reviewed)
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| 7. |
- Reichel, L., et al.
(author)
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Increased magnetocrystalline anisotropy in epitaxial Fe-Co-C thin films with spontaneous strain
- 2014
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 116:21, s. 213901-
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Journal article (other academic/artistic)abstract
- Rare earth free alloys are in focus of permanent magnet research since the accessibility of the elements needed for nowadays conventional magnets is limited. Tetragonally strained iron-cobalt (Fe-Co) has attracted large interest as promising candidate due to theoretical calculations. In experiments, however, the applied strain quickly relaxes with increasing film thickness and hampers stabilization of a strong magnetocrys- talline anisotropy. In our study we show that already 2 at% of carbon substantially reduce the lattice relaxation leading to the formation of a spontaneously strained phase with 3% tetragonal distortion. In these strained (Fe0.4Co0.6)0.98C0.02 films, a magnetocrystalline anisotropy above 0.4 MJ/m3 is observed while the large polarization of 2.1 T is maintained. Compared to binary Fe-Co this is a remarkable improve- ment of the intrinsic magnetic properties. In this paper, we relate our experimental work to theoretical studies of strained Fe-Co-C and find a very good agreement.
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| 8. |
- Salikhov, R., et al.
(author)
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Enhanced spin-orbit coupling in tetragonally strained Fe-Co-B films
- 2017
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In: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:27
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Journal article (peer-reviewed)abstract
- Tetragonally strained interstitial Fe-Co-B alloys were synthesized as epitaxial films grown on a 20 nm thick Au0.55Cu0.45 buffer layer. Different ratios of the perpendicular to in-plane lattice constant c/a = 1.013, 1.034 and 1.02 were stabilized by adding interstitial boron with different concentrations 0, 4, and 10 at.%, respectively. Using ferromagnetic resonance (FMR) and x-ray magnetic circular dichroism (XMCD) we found that the total orbital magnetic moment significantly increases with increasing c/a ratio, indicating that reduced crystal symmetry and interstitial B leads to a noticeable enhancement of the effect of spin-orbit coupling (SOC) in the Fe-Co-B alloys. First-principles calculations reveal that the increase in orbital magnetic moment mainly originates from B impurities in octahedral position and the reduced symmetry around B atoms. These findings offer the possibility to enhance SOC phenomena - namely the magnetocrystalline anisotropy and the orbital moment - by stabilizing anisotropic strain by doping 4 at.% B. Results on the influence of B doping on the Fe-Co film microstructure, their coercive field and magnetic relaxation are also presented.
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| 9. |
- Ahlbäck, Sven, 1960-
(author)
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Melody Beyond Notes : A Study of Melody Cognition
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Abstract Melody beyond notes - a study of melody cognition Keywords: Melody, Cognition, Melodic segmentation, Melodic Parallelism, Pitch Structure,Meter, Rhythm, Grouping, Swedish Folk Music, Music Theory, Computer-aided analysis This thesis is a music theoretical approach to cognition of surface structure in monophonic melodies. It can briefly be described as a study into what extent we may acquire a common experience of melodic structure, such as phrase structure, only from listening to a melody. More precisely, this work concerns the question as to whether a cognitively based method of analysis can provide analyses of melodic surface structures in different styles thatwill concur with listeners’ conceptions better than chance. In order to investigate this question a general model of melody cognition wasdeveloped, relying primarily on a few general cognitive principles. The model was designed to be general in the sense that it should apply to any style for which the concept of melody is relevant. This model provided the framework for a computer-aided method of analysis, which performs analysis of different aspects of melodic surface structure based on information of relative pitch and temporal information only. These aspects involve: Categorical perception of pitch and duration at basic levels, such as context-sensitive quantization and melodic pitch categorization; Analysis of metrical and non-metrical temporal structures, e,g. heterometric structures; phrase and section structure, including analysis of structural implications of melodic similarity, structural hierarchy and symmetry. This development has required new theoretical concepts and methods to be created, e.g. regarding the relationship between rhythm and meter, some of which are presented for the first time is this thesis.In order to evaluate the performance of the model a series of listener tests were performed, which together with corpuses of musical notations from different styles, constituted the reference material of the study. This material has included Scandinavian folk music styles and Western classical music, but also examples of Eastern European folk music, Middle East and Indian Classical music, Jazz and Western popular song.The results of these tests indicated that melody can be conceived differently by people even within a limited cultural sphere. But the results also suggested that this variability is possible to model by a rule-based method of analysis, since the predictions given by the model generally were well above chance level. It is herein suggested that variability in grouping conception to a considerable degree can be accounted for in terms of start- and end-oriented grouping preference. Moreover, the results also indicate that important aspects of even culturally foreign music can be conveyed, also in limited melodic stimuli.Generally, the results support the assumption of a general cognitive framework for melodic surface structure. This might be interpreted as to indicate that, metaphorically speaking; melody may indeed be a universal ‘language’, but one which we all understand in our own way.
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| 10. |
- Augustsson, A, et al.
(author)
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The electronic structure and lithiation of electrodes based on vanadium-oxide nanotubes
- 2003
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In: Journal of Applied Physics. ; 94:8, s. 5083-5087
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Journal article (peer-reviewed)abstract
- The synthesis of a novel ligand 2′-[1-(2-pyridinyl)-ethylidene]-oxamohydrazide (Hapsox), from a series of 2-acetylpyridine acylhydrazones, and its complex with Co(III), which is the first in this series of complexes are described. Both the ligand and the complex were characterized by elemental analysis, IR, 1H-NMR, and 13C-NMR spectra, and the structure of the complex [Co(apsox)2]ClO4 was determined by X-ray structural analysis. It was established that [Co(apsox)2]ClO4 has an octahedral geometry with two tridentate apsox ligands in monoanionic form. Structural characteristics, lengths of the bonds, and angles between the bonds were typical for Co(III) complexes of distorted octahedral geometry. Both direct and template synthesis afforded the same geometrical isomer of the complex with two apsox ligands meridionally bound to the central metal ion, even in the case when equimolar quantities of Co(ClO4)2 and Hapsox were applied.
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