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"Üstüner, K."
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Replacement and Original Magnet Engineering Options (ROMEOs): A European Seventh Framework Project to Develop Advanced Permanent Magnets Without, or with Reduced Use of, Critical Raw Materials
2015
The rare-earth crisis, which peaked in the summer of 2011 with the prices of both light and heavy rare earths soaring to unprecedented levels, brought about the widespread realization that the long-term availability and price stability of rare earths could not be guaranteed. This triggered a rapid response from manufacturers involved in rare earths, as well as governments and national and international funding agencies. In the case of rare-earth-containing permanent magnets, three possibilities were given quick and serious consideration: (I) increased recycling of devices containing rare earths; (II) the search for new, mineable, rare-earth resources beyond those in China; and (III) the development of high-energy-product permanent magnets with little or no rare-earth content used in their manufacture. The Replacement and Original Magnet Engineering Options (ROMEO) project addresses the latter challenge using a two-pronged approach. With its basis on work packages that include materials modeling and advanced characterization, the ROMEO project is an attempt to develop a new class of novel permanent magnets that are free of rare earths. Furthermore, the project aims to minimize rare-earth content, particularly heavy-rare-earth (HRE) content, as much as possible in Nd-Fe-B-type magnets. Success has been achieved on both fronts. In terms of new, rare-earth-free magnets, a Heusler alloy database of 236,945 compounds has been narrowed down to approximately 20 new compounds. Of these compounds, Co
2
MnTi is expected to be a ferromagnet with a high Curie temperature and a high magnetic moment. Regarding the reduction in the amount of rare earths, and more specifically HREs, major progress is seen in electrophoretic deposition as a method for accurately positioning the HRE on the surface prior to its diffusion into the microstructure. This locally increases the coercivity of the rather small Nd-Fe-B-type magnet, thereby substantially reducing the dependence on the HREs Dy and Tb, two of the most critical raw materials identified by the European Commission. Overall, the ROMEO project has demonstrated that rapid progress can be achieved when experts in a specific area are brought together to focus on a particular challenge. With more than half a year of the ROMEO project remaining, further progress and additional breakthroughs can be expected.
Journal Article
Model for Calculating J( H) Curves of Ni Coated Nd-Fe-B Magnets
2006
An analytical model to describe the influence of surface degradation and the Ni layer itself on the magnetic properties of Ni coated Nd-Fe-B magnets is presented. Starting from the bulk magnetic properties, the dimensions, the thickness of Ni coating and the affected surface layer,
J(
H) demagnetization curve is calculated. Subsequently the expected values of (
BH)
max, and the reversible permeability are deduced from the calculated
J(
H) curves. For flat magnets the surface effects lead to a decrease of
B
r and an increase of the permeability which lowers (
BH)
max. For strait magnets a step in the
J(
H) curve appears at
H = 0. The deteriorating effect of Ni coating and the surface layer scale with the dimensions of magnet and the thickness of these layers, which depend on the processing and the grain size of magnet. These effects can not be neglected if one or more dimensions of a Ni coated magnet are less than about 5 mm. SmCo
5 magnets show similar effects but the coercivity of the damaged surface layer is higher. Pinning type Sm
2Co
17 magnets show almost no deterioration on surface due to machining. As a result, Sm-Co magnets are better suited for applications with dimensions smaller than about 2 mm.
Journal Article
Towards engineering the perfect defect in high-performing permanent magnets
2023
Permanent magnets draw their properties from a complex interplay, across multiple length scales, of the composition and distribution of their constituting phases, that act as building blocks, each with their associated intrinsic properties. Gaining a fundamental understanding of these interactions is hence key to decipher the origins of their magnetic performance and facilitate the engineering of better-performing magnets, through unlocking the design of the \"perfect defects\" for ultimate pinning of magnetic domains. Here, we deployed advanced multiscale microscopy and microanalysis on a bulk Sm2(CoFeCuZr)17 pinning-type high-performance magnet with outstanding thermal and chemical stability. Making use of regions with different chemical compositions, we showcase how both a change in the composition and distribution of copper, along with the atomic arrangements enforce the pinning of magnetic domains, as imaged by nanoscale magnetic induction mapping. Micromagnetic simulations bridge the scales to provide an understanding of how these peculiarities of micro- and nanostructure change the hard magnetic behaviour of Sm2(CoFeCuZr)17 magnets. Unveiling the origins of the reduced coercivity allows us to propose an atomic-scale defect and chemistry manipulation strategy to define ways toward future hard magnets.
THE ISPRS STUDENT CONSORTIUM: SUSTAINING RELEVANCE AND CREATING SHARED VISIONS FOR THE YOUTH
2020
The ISPRS Student Consortium (ISPRS SC) continues to engage the youth in many activities aligned with the mission and vision of ISPRS. For the term 2016 – 2020, the ISPRS SC strengthened its foundations through collaboration within the ISPRS Council and Technical Commission V, and increasing its presence in various ISPRS events. The Consortium Board introduced several changes in the organization: (1) re-designed the official logo, which was used in different communication and media, (2) revision of the Consortium’s Statutes, (3) continued the legacy of the summer schools through a new set of guidelines that coordinated all summer schools organized within ISPRS, (4) launched the Webinar Series, (5) repackaged the Newsletter into SpeCtrum, (6) introduction of two new awards, (7) hosting of a three-day Youth Forum in the ISPRS Congress and (8) the introduction of the ISPRS SC Student Chapters. A total of 13 issues had been published under SpeCtrum, two of which featured the ISPRS and an outstanding special issue on Women in Remote Sensing and Geospatial Information that received over 500 reads overnight. The SpeCtrum continued to seek experts, professors and contributors who willingly shared their work and inspire the youth. SpeCtrum had been publishing high quality articles and had been featuring outstanding scientists and researchers in the fields of remote sensing, photogrammetry and spatial information science. The Consortium also launched the Webinar Series and kicked off with an introduction on Google Earth Engine and followed by the applications of deep learning in remote sensing in 2020. For this term, a total of 16 summer schools were hosted across the globe, including one hosted under the ISPRS Education and Capacity Building Initiatives in 2018. The Consortium also partnered with international organizations such as Geo-informatics and Space Technology Development Agency, ASEAN Research and Training Center for Space Technology and Applications and the local chapters of the IEEE – Geosciences and Remote Sensing Society Young Professionals (IEEE – GRSS YP) in Brazil. The members of the Consortium had been increasing in the past year, especially with its increased presence in various social media platforms. The Consortium envisions a future, where the younger generation takes the lead and engages in relevant social and global issues and contributing significantly to the scientific community. As a student and youth organization, it aims to continue to develop more ways of knowledge transfer, capacity building and establishing professional networks to prepare students and young professionals for a future of collaboration and cooperation.
Journal Article