Europe's rare earth element resource potential: an overview of REE metallogenetic provinces and their geodynamic setting

Security of supply of a number of raw materials is of concern for the European Union; foremost among these are the rare earth elements (REE), which are used in a range of modern technologies. A number of research projects, including the EURARE and ASTER projects, have been funded in Europe to investigate various steps along the REE supply chain. This paper addresses the initial part of that supply chain, namely the potential geological resources of the REE in Europe. Although the REE are not currently mined in Europe, potential resources are known to be widespread, and many are being explored. The most important European resources are associated with alkaline igneous rocks and carbonatites, although REE deposits are also known from a range of other settings. Within Europe, a number of REE metallogenetic belts can be identified on the basis of age, tectonic setting, lithological association and known REE enrichments. This paper reviews those metallogenetic belts and sets them in their geodynamic context. The most well-known of the REE belts are of Precambrian to Palaeozoic age and occur in Greenland and the Fennoscandian Shield. Of particular importance for their REE potential are the Gardar Province of SW Greenland, the Svecofennian Belt and subsequent Mesoproterozoic rifts in Sweden, and the carbonatites of the Central Iapetus Magmatic Province. However, several zones with significant potential for REE deposits are also identified in central, southern and eastern Europe, including examples in the Bohemian Massif, the Iberian Massif, and the Carpathians

Ferromagnetic resonance in Mn 5 Ge 3 epitaxial films with weak stripe domain structure

International audienceExtensive X-band and Q-band FMR experiments have been performed in the Mn5Ge3 epitaxial films with thicknesses varying between 4.5 and 68 nm. FMR signals were recorded in the temperature range between 15 and 295 K, at different orientations of magnetic field with respect to the film plane. In addition to the acoustic FMR mode with well defined resonance field, originating from inside the magnetic domains, a broad absorption line has been observed at low fields and attributed to the unresolved spectrum of FMR modes having the origin in flux closure caps. The FMR results have been discussed in the context of the domain structure computed with the use of OOMMF micromagnetic calculations and giving good agreement with the experimental hysteresis curves. From the Q-band experiments, where the FMR signal is observed in the magnetically saturated sample, the uniaxial anisotropy constant in films with different thicknesses has been determined as a function of temperature. This FMR study provides the evidence that the strong uniaxial anisotropy observed in epitaxial thin films of Mn5Ge3 leads to the formation of a stripe domain structure above 25 nm, in agreement with the published reports on magnetization studies in these films. It also eliminates a possible confusion that may arise from previously published FMR studies on films grown with the same method, which led their authors to conclude that the shape anisotropy can force the magnetization to the in-plane orientation in this thickness range and even above it

Resourcing the Fairytale Country with Wind Power: A Dynamic Material Flow Analysis

Wind energy is key to addressing the global climate challenge, but its development is subject to potential constraints of finite primary materials. Prior studies on material demand forecasting of wind power development are often limited to a few materials and with low technological resolution, thus hindering a comprehensive understanding of the impact of microengineering parameters on the resource implications of wind energy. In this study, we developed a component-by-component and stock-driven prospective material flow analysis model and used bottom-up data on engineering parameters and wind power capacities to characterize the materials demand and secondary supply potentials of wind energy development in Denmark, a pioneering and leading country in wind power. We also explicitly addressed the uncertainties in the prospective modeling by the means of statistical estimation and sensitivity analysis methods. Our results reveal increasing challenges of materials provision and end-of-life (EoL) management in Denmark's ambitious transition toward 100% renewable energy in the next decades. Harnessing potential secondary resource supply from EoL and extending lifetime could curtail the primary material demand, but they could not fully alleviate the material supply risk. Such a model framework that considers bottom-up engineering parameters with increased precision could be applied to other emerging technologies and help reveal synergies and trade-offs of relevant resource, energy, and climate strategies in the future renewable energy and climate transition