1,721,151 research outputs found
Advancing recycling of end-of-life NdFeB permanent magnets for additive manufacturing
No full textRecycling end-of-life rare-earth-based permanent magnets, which are key components across many strategic sectors, offers a promising solution to address the geopolitical, economic, and environmental issues of the rare-earth industry. Among the proposed strategies, the magnet-to-magnet approach, where end-of-life magnets are transformed into fine powders to manufacture new magnets, has attracted considerable attention as it allows for complete material recovery and waste minimization through environmentally friendly processes. While the best performance can be obtained by using the powders to produce sintered magnets, additive manufacturing, especially the fused filament fabrication 3D printing technology using magnetic polymer composites as inks, has emerged as a promising and sustainable method for manufacturing bonded permanent magnets with complex geometries while minimizing waste production. This PhD research aims to advance sustainable methods for producing NdFeB magnets by recycling EoL products. The primary focus was on exploring magnet-to-magnet recycling techniques to create powders with micrometer-scale dimensions and magnetic properties similar to those of the original magnets, thus enabling their use in producing novel permanent magnets, particularly through 3D printing. The process involved pulverizing the magnets through hydrogen decrepitation, followed by high-energy ball milling to generate fine powders. These powders were then used to create dense pellets, demonstrating the feasibility of manufacturing new permanent magnets from recycled materials. Additionally, preliminary studies with commercial NdFeB powders were conducted to evaluate the potential for producing NdFeB-based polymer composites and 3D printing filaments. Furthermore, advanced modeling and simulations were used to study the alignment of recycled NdFeB powders within polymer matrices under an applied magnetic field, offering valuable insights for the production of high-performance anisotropic permanent magnets via magnetic-field-assisted 3D printing. The research findings confirm that sustainable methods for producing NdFeB magnets from recycled end-of-life products are indeed feasible. Key processes, such as hydrogen decrepitation and high-energy ball milling, were optimized to generate micrometer-sized powders with magnetic properties comparable to those of original magnets. While recycled magnets may not fully replicate the performance of their original counterparts, they can effectively bridge the gap between ferrites and high-performance NdFeB, making them suitable for lower-performance applications. The study also demonstrated that dense pellets with uniform magnetic characteristics can be produced, underscoring the potential for using recycled powders to manufacture new magnets. Additionally, preliminary investigations with commercial NdFeB powders indicated that magnetic polymer composites with controlled thermal and magnetic properties can be developed for 3D printing applications. Furthermore, the research showed that recycled powders can be aligned within polymer matrices using an external magnetic field, with alignment efficiency influenced by factors such as field strength, particle shape, and initial orientation, as well as interparticle interaction, thereby enhancing their applicability in 3D printing. These findings contribute significantly to the development of high-performance permanent magnets from recycled materials, promoting sustainability in magnet production
Magnetic properties of spinel ferrite nanoparticles: Influence of the magnetic structure
No full textDesign of Magnetic Spinel Oxide Nanoarchitetures
No full textUnderstanding the interplay among chemical, microstructural and physical properties is the key to design new materials.
In this framework the intrinsic versatility of chemical science can give a wide and at the same time deep view, allowing to correlate
synthesis and properties. This contribution focuses on the design of magnetic nanostructured spinel oxides, describing how
to manipulate the matter to realize nanoarchitectures, in order to govern the magnetic properties
Structural, microstructural and magnetic properties of (La1-xCax)MnO3 nanoparticles
No full textThe crystal and magnetic structures of 10 and 20 nm sized (La1-xCax)MnO3 (x = 0.37, 0.50, 0.75) have been investigated between 5 and 300 K by means of Rietveld refinement of neutron powder diffraction data, coupled with transmission electron microscope observation and magnetization measurements. TEM observation reveals that nanoparticles are strongly affected by strain fields, probably originating from surface pressure. Irrespective of the composition, charge and orbital orderings are suppressed and F-z and C-y spin orderings coexist at low temperature; C-y and F-z orderings likely occur within the strained regions of the nanoparticles and in the matrix respectively. Moreover G(z) and A(z) orderings are sometimes observed, and are likely to be taking place at the border of the strained regions. RI Peddis, Davide/J-8556-201
Dialogo tra le scienze. Linguaggi, metodi e modelli per un “nuovo umanesimo scientifico”
Full text linkThe paper presents and discusses the dialogue between the humanities and STEM disciplines, with a particular focus on the encounter between philosophy and physical chemistry. The perspective is to overcome the concept of ‘two cultures’ by describing some positive experiences of cross- and multidisciplinary research in the exercise of dialogue and mutual exchange in the construction of interdisciplinarity. Overcoming disciplinary boundaries, as we have tried to describe, is very complex, it requires a continuous effort of translation from one language to another, a translation between different cultures and different world views. For this reason, interdisciplinarity is not considered in this article as an arrival point, but as a journey, a project that goes through different stages of exchanges (cross-disciplinarity) and collaboration (multidisciplinarity)
Exchange Bias in Fe@Cr Core-Shell Nanoparticles
No full textWe have used X-ray magnetic circular dichroism and magnetometry to study isolated Fe@Cr core-shell nanoparticles with an Fe core diameter of 2.7 nm (850 atoms) and a Cr shell thickness varying between 1 and 2 monolayers. The addition of Cr shells significantly reduces the spin moment but does not change the orbital moment. At least two Cr atomic layers are required to stabilize a ferromagnetic/antiferromagnetic interface and generate the associated exchange bias and increase in coercivity. RI Kroeger, Roland/D-5321-2012; Lari, Leonardo/D-6844-2012; Peddis, Davide/J-8556-201
Approaches to Synthesis and Characterization of Spherical and Anisometric Metal Oxide Magnetic Nanomaterials
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Hysteretic NanoSQUID Sensors for Investigation of Iron Oxide Nanoparticles
No full textMagnetic nanosensors based on niobium nano superconducting quantum interference device (nanoSQUID) have been fabricated and employed to investigate the magnetic properties of iron oxide nanoparticles. The nanoSQUIDs, fabricated by electron beam lithography, consist in a square loop interrupted by two nanometric constrictions (Dayem bridges). The flux capture area is 0.5 mu m(2) while the Dayem nanobridges have a width and a length ranging from 50 to 90 nm and 70 to 80 nm, respectively. Measurements of current to voltage (I-V) and critical current to magnetic flux (I-C-Phi) characteristics have been reported for different nanobridge dimensions. At T = 4.2 K the nanosensors have shown a hysteretic I-V characteristic and a triangular shaped I-Phi pattern suggesting a strong deviation from sinusoidal current-phase relationship. Due to the hysteretic behavior, the devices have been employed as a magnetic flux to current transducer. In such a configuration an overall magnetic flux resolution of about 0.3 m Phi(0) has been estimated. These nanosensors have been successfully employed to measure the field dependence and the time relaxation of the magnetization of iron oxide nanoparticles having a mean diameter of 4.2 nm. The experimental curves undoubtedly prove that the nanoSQUIDs reported here can be successfully employed to investigate the magnetic properties of very small nanoparticles. RI Peddis, Davide/J-8556-2013; Russo, Roberto/A-8576-2010 OI Russo, Roberto/0000-0001-9431-626
Horizon Europe and Gender+: a focus on Nano Science and Technology.
No full textIn the last few decades, addressing gender balance and equal opportunities in EU funded proposals has become increasingly widespread and is generally accepted and implemented. The European Union has promoted the adoption of three strategies. Fix the Numbers: focuses on increasing women's and other under-represented groups’ participation; Fix the Institutions: promotes inclusive equality in careers through structural change in research organizations; Fix the Knowledge (or "gendered innovations"): stimulates excellence in science and technology by integrating sex, gender,
and intersectional analysis into research.
Since January 2022, a Gender Equality Plan (GEP), or equivalent strategy, has been an eligibility criterion of the EU Horizon Europe programme. However, the link between this programmatic document and the content of the research projects is still unclear. The authors analysed the literature in the nanotechnology sector, identifying articles that paid attention to gender equality and adopting a gender perspective in research paths to identify the strategies adopted and the results obtained. Some older articles reflect the need to "fix the numbers" and "fix the institutions" [1] [2], while more
recent research shows the importance of classifying individuals not only through the XX female / XY male dichotomy but also by considering various biological, cultural and socioeconomic factors [3]. Currently, researchers, funding agencies, peer-reviewed journals and universities are coordinating
efforts to implement robust methods of sex and gender analysis [4]. However, for many scientists, adopting this perspective requires rethinking their approach to research, which is even more complicated when dealing with fundamental research on materials.
This paper focuses on an ongoing Horizon Europe research project on microfabrication, magnetism, electroplating, photovoltaics and related subjects. To promote a gender+ perspective, the authors are implementing several micro-actions throughout the project's duration, including specific
activities connected to gender-related topics, integrating specific strategies into the tasks and deliverables, and collecting and analysing disaggregated data in the outreach tasks. The experience seeks to be replicated in future projects, where adopting a gender+ perspective could benefit the
research community and society
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