Metalle unter extremen Bedingungen
Zusammenfassung der Projektergebnisse
Metals are known for a long time. They are shiny liquids as mercury or malleable solids as aluminum. Metals conduct electricity, but also heat, even convert one into the other as thermoelectric material. Metals can become superconductors by loosing all their resistivity below some critical temperature, so that they are able to carry lossless currents for many years. The theoretical understanding of the phenomena lead to various models that culminated in the Fermi liquid description, from which their superconductivity can follow. The Fermi liquid scenario is very well understood, and the question often is by how much and why real metals deviate with their properties from it. Ab-initio calculations advanced over the years so that even detailed properties can be calculated today. Semiconductors, e.g. transistors or solar cells, are distinctly different from metals, yet quite well understood, different from other exotic conductors. Here the proposal was, not to look at exotic materials, but start with very well behaved metals and expose them to extreme conditions and to find out whether at all, or how this influences the proper metallic behavior. While this is interesting from a general science point of view, modern applications of metals raise that question, as well. Nanotechnologies make a metal’s surface to volume ratio very large so that the external surface may change the behavior of the bulk. This may bear similarities to bulk metals if they undergo high pressure that will penetrate throughout. Nuclear magnetic resonance (NMR) is a powerful method that reacts to the chemical as well as electronic structure of materials, in particular also to atomic motion and metallic electrons. Therefore, NMR investigations of metals under high-pressure or nanoconfinement are very sensible. In particular, the Leipzig NMR group was taking new steps in high-sensitivity, high-pressure NMR, and our Russian collaborators are experts in preparation of nano-confined metals. The results of our investigation are two-fold. Firstly, we could indeed develop and build highly sensitive high-pressure anvil cells for NMR that carry us in pressure regions which allow us to change the chemical and electronic structure of metals (and other materials). This is important since this method is not straightforward in the necessary Giga-Pascal region of pressures (often more than 100000 atmospheres of pressure). With it, secondly, we could observe a large number of phenomena: liquid metals become solid single crystals metals under pressure; changes in the atomic motion of liquids, which correlate with changes in the metal properties; turn a thermoelectric material into a metal at high pressure; how nano-confinement changes in the atomic motion, as well as the chemical structural, including polymorphism of simple metals. With this knowledge and the new capabilities one can approach many systems, now, in particular those that are of interest from a theoretical or applied point of view, and search for a deep understanding of the conducting and superconducting properties.
Projektbezogene Publikationen (Auswahl)
- High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions, J. Vis. Exp., 92 (2014): e52243
T. Meier and J. Haase
(Siehe online unter https://doi.org/10.3791/52243) - Moissanite anvil cell design for Giga-Pascal nuclear magnetic resonance, Rev. Sci. Instrum., 85 (4), 043903 (2014)
T. Meier, T. Herzig and J. Haase
(Siehe online unter https://doi.org/10.1063/1.4870798) - Anvil Cell Gasket Design for High Pressure Nuclear Magnetic Resonance Experiments Beyond 30 GPa, Rev. Sci. Instrum., 86 (12), 123906 (2015)
T. Meier and J. Haase
(Siehe online unter https://doi.org/10.1063/1.4939057) - Diffusion slowdown in the nanostructured liquid Ga-Sn alloy, Annalen der Physik, 2015, 527, 3–4, 248–253
D. Y. Podorozhkin, E. V. Charnaya, M. K. Lee, L. J. Chang, J. Haase, D. Michel, Yu. A. Kumzerov, A. V. Fokin
(Siehe online unter https://doi.org/10.1002/andp.201400174) - High-sensitivity NMR beyond 200,000 atmospheres of pressure, J. Magn. Res., 257 (2015), 39–44
T. Meier, S. Reichardt and J. Haase
(Siehe online unter https://doi.org/10.1016/j.jmr.2015.05.007) - High Sensitivity Nuclear Magnetic Resonance at Extreme Pressures, PhD Thesis, Leipzig 2016
T. Meier
- Nuclear Magnetic Resonance Investigation of Metallic Sodium Nanoparticles in Porous Glass, Physics of the Solid State, 2016, 58, 6, 1234-1238
A. V. Uskov, D. Yu. Nefedov, E. V. Charnaya, E. V. Shevchenko, J. Haase, D. Michel, Yu. A. Kumzerov, A. V. Fokin, and A. S. Bugaev
(Siehe online unter https://doi.org/10.1134/S1063783416060330) - Polymorphism of metallic sodium under nanoconfinement, NanoLetters 2016, 16, 1, 791-794
A. V. Uskov, D. Yu. Nefedov, E. V. Charnaya, J. Haase, D. Michel, Yu. A. Kumzerov, A. V. Fokin, A. S. Bugaev
(Siehe online unter https://doi.org/10.1021/acs.nanolett.5b04841) - At Its Extremes: NMR at Giga-Pascal Pressures, Ann. Reports on NMR Spectroscopy 2018, 93, 1-74
T. Meier
(Siehe online unter https://doi.org/10.1016/bs.arnmr.2017.08.004) - NMR and ab initio study of gallium metal under pressure, Phys. Rev. B, 2019, 99, 125121-9
R. Řezníček, V. Chlan, J. Haase
(Siehe online unter https://doi.org/10.1103/PhysRevB.99.125121)
