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| 2. |
- Benedek, Peter, et al.
(författare)
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Quantifying Diffusion through Interfaces of Lithium-Ion Battery Active Materials
- 2020
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 12:14, s. 16243-16249
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Tidskriftsartikel (refereegranskat)abstract
- Detailed understanding of charge diffusion processes in a lithium-ion battery is crucial to enable its systematic improvement. Experimental investigation of diffusion at the interface between active particles and the electrolyte is challenging but warrants investigation as it can introduce resistances that, for example, limit the charge and discharge rates. Here, we show an approach to study diffusion at interfaces using muon spin spectroscopy. By performing measurements on LiFePO4 platelets with different sizes, we determine how diffusion through the LiFePO4 (010) interface differs from that in the center of the particle (i.e., bulk diffusion). We perform ab initio calculations to aid the understanding of the results and show the relevance of our interfacial diffusion measurement to electrochemical performance through cyclic voltammetry measurements. These results indicate that surface engineering can be used to improve the performance of lithium-ion batteries.
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| 3. |
- Gao, Shang, et al.
(författare)
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Dipolar Spin Ice States with a Fast Monopole Hopping Rate in CdEr2X4 (X = Se, S)
- 2018
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 120:13
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Tidskriftsartikel (refereegranskat)abstract
- Excitations in a spin ice behave as magnetic monopoles, and their population and mobility control the dynamics of a spin ice at low temperature. CdEr2Se4 is reported to have the Pauling entropy characteristic of a spin ice, but its dynamics are three orders of magnitude faster than the canonical spin ice Dy2Ti2O7. In this Letter we use diffuse neutron scattering to show that both CdEr2Se4 and CdEr2S4 support a dipolar spin ice state-the host phase for a Coulomb gas of emergent magnetic monopoles. These Coulomb gases have similar parameters to those in Dy2Ti2O7, i.e., dilute and uncorrelated, and so cannot provide three orders faster dynamics through a larger monopole population alone. We investigate the monopole dynamics using ac susceptometry and neutron spin echo spectroscopy, and verify the crystal electric field Hamiltonian of the Er3+ ions using inelastic neutron scattering. A quantitative calculation of the monopole hopping rate using our Coulomb gas and crystal electric field parameters shows that the fast dynamics in CdEr2X4 (X = Se, S) are primarily due to much faster monopole hopping. Our work suggests that CdEr2X4 offer the possibility to study alternative spin ice ground states and dynamics, with equilibration possible at much lower temperatures than the rare earth pyrochlore examples.
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| 4. |
- Nocerino, Elisabetta, et al.
(författare)
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Multiple unconventional charge density wave transitions in LaPt2Si2 superconductor clarified with high-energy X-ray diffraction
- 2023
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Ingår i: Communications Materials. - : Springer Nature. - 2662-4443. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- The quasi-2D platinum-based rare earth intermetallic LaPt2Si2 has attracted attention as it exhibits strong interplay between charge density wave order and superconductivity. However, most of the results reported on this material come from theoretical calculations, preliminary bulk investigations and powder samples, which makes it difficult to uniquely determine the temperature evolution of its crystal structure and, consequently, of its charge density wave transition. Therefore, the published literature around LaPt2Si2 is often controversial. Here, by means of high-resolution synchrotron X-ray diffraction data, we clarify some of the poorly or partially understood aspects of the physics of LaPt2Si2. In particular, we resolve the complex evolution of its crystal structure and superstructures, identifying the temperature dependence of multiple density wave transitions in good quality LaPt2Si2 single crystals. According to our findings, on cooling from room temperature LaPt2Si2 undergoes a series of subtle structural transitions which can be summarised as follows: second order commensurate tetragonal (P4/n m m)-to-incommensurate structure followed by a first order incommensurate-to-commensurate orthorhombic (P m m n) transition and then a first order commensurate orthorhombic (P m m n)-to-commensurate tetragonal (P4/n m m). The structural transitions are accompanied by both incommensurate and commensurate superstructural distortions of the lattice. The observed behavior is compatible with discommensuration of the CDW in this material.
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| 5. |
- Nocerino, Elisabetta, et al.
(författare)
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Structural Evolution and Onset of the Density Wave Transition in the CDW Superconductor LaPt2Si2 Clarified with Synchrotron XRD
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The quasi-2D Pt-based rare earth intermetallic material LaPt2Si2 has attracted attention as it exhibits strong interplay between charge density wave (CDW) and and superconductivity (SC). However, the most of the results reported on this material come from theoretical calculations, preliminary bulk investigations and powder samples, which makes it difficult to uniquely determine the temperature evolution of its crystal structure and, consequently, of its CDW transition. Therefore, the published literature around LaPt2Si2 is often controversial. In this paper, we clarify the complex evolution of the crystal structure, and the temperature dependence of the development of density wave transitions, in good quality LaPt2Si2 single crystals, with high resolution synchrotron X-ray diffraction data. According to our findings, on cooling from room temperature LaPt2Si2 undergoes a series of subtle structural transitions which can be summarised as follows: second order commensurate tetragonal (P4/nmm)-to-incommensurate structure followed by a first order incommensurate-to-commensurate orthorhombic (Pmmn) transition and then a first order commensurate orthorhombic (Pmmn)-to-commensurate tetragonal (P4/nmm). The structural transitions are accompanied by both incommensurate and commensurate superstructural distortions of the lattice. The observed behavior is compatible with discommensuration of the CDW in this material.
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| 6. |
- Papadopoulos, Konstantinos, 1989, et al.
(författare)
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Influence of the magnetic sublattices in the double perovskite LaCaNiReO6
- 2022
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9969 .- 2469-9950. ; 106:21
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Tidskriftsartikel (refereegranskat)abstract
- The magnetism of double perovskites is a complex phenomenon, determined from intra- or interatomic magnetic moment interactions, and strongly influenced by geometry. We take advantage of the complementary length and timescales of the muon spin rotation, relaxation, and resonance (μ+SR) microscopic technique and bulk ac/dc magnetic susceptibility measurements to study the magnetic phases of the LaCaNiReO6 double perovskite. As a result, we are able to discern and report ferrimagnetic ordering below TC=102K and the formation of different magnetic domains above TC. Between TC270K. An evolution of the interaction between Ni and Re magnetic sublattices, in this geometrically frustrated fcc perovskite structure, is revealed as a function of temperature through the critical behavior and thermal evolution of microscopic and macroscopic physical quantities.
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