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- Matsubara, Nami, et al.
(författare)
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Cation Distributions and Magnetic Properties of Ferrispinel MgFeMnO4
- 2020
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:24, s. 17970-17980
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure and magnetic properties of the cubic spinel MgFeMnO4 were studied by using a series of in-house techniques along with large-scale neutron diffraction and muon spin rotation spectroscopy in the temperature range between 1.5 and 500 K. The detailed crystal structure is successfully refined by using a cubic spinel structure described by the space group Fd3¯ m. Cations within tetrahedral A and octahedral B sites of the spinel were found to be in a disordered state. The extracted fractional site occupancies confirm the presence of antisite defects, which are of importance for the electrochemical performance of MgFeMnO4 and related battery materials. Neutron diffraction and muon spin spectroscopy reveal a ferrimagnetic order below TC = 394.2 K, having a collinear spin arrangement with antiparallel spins at the A and B sites, respectively. Our findings provide new and improved understanding of the fundamental properties of the ferrispinel materials and of their potential applications within future spintronics and battery devices.
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- Sugiyama, Jun, et al.
(författare)
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Nuclear magnetic field in Na0.7CoO2 detected with mu-SR
- 2020
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:14
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Tidskriftsartikel (refereegranskat)abstract
- The internal magnetic field in a sodium battery compound, i.e., the paramagnet Na0.7CoO2, was investigated with negative muon spin rotation and relaxation (mu-SR), and the result was compared with the results previously obtained with mu+SR. The majority of implanted mu(-) is captured on an oxygen nucleus, while mu(+) locates an interstitial site. Therefore, a mu(+/-) SR work provides information on the internal magnetic field, which is formed by nuclear magnetic moments of Na-23 and Co-59, from the two different viewpoints. Besides a slight decrease in the field distribution width (Delta) around 300 K, the nuclear magnetic field detected with mu- SR was found to be almost static and temperature independent up to 400 K, even though Na ions are known to start to diffuse above 290 K based on mu(+) SR, Na-NMR, neutron scattering, and electrochemical measurements. Such a discrepancy is caused by the fact that the Na contribution to Delta is only about 3% at the O site whereas it is about 13% at the interstitial site, where the mu(+) is presumably located.
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