Spin fluctuations above 100 K in stoichiometric LiCoO2

13th International Conference on Muon Spin Rotation, Relaxation and Resonance

Mukai, K.^1 ; Aoki, Y.^1 ; Andreica, D.^2 ; Amato, A.^3 ; Watanabe, I.^4 ; Giblin, S.R.^5 ; Sugiyama, J.^1

Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi

480-1192, Japan^1

Faculty of Physics, Babes-Bolyai University, Cluj-Napoca

400084, Romania^2

Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Villigen PSI

CH-5232, Switzerland^3

Advanced Meson Science Laboratory, Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama

351-0198, Japan^4

School of Physics and Astronomy, Cardiff University, Queens Building, The Parade, Cardiff

zCF24 3AA, United Kingdom^5

关键词: Electron paramagnetic resonances (EPR);    Intrinsic characteristics;    Magnetic nature;    Measurement techniques;    Muonium formation;    Paramagnetic behavior;    Positive electrode materials;    Temperature dependence;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/551/1/012008/pdf
DOI  :  10.1088/1742-6596/551/1/012008

来源: IOP

【 摘 要 】

Although stoichiometric lithium cobalt dioxide LiCoO2 (ST-LCO) is the most common positive electrode material for Li-ion batteries, the magnetic nature of ST-LCO is still not fully understood. Therefore, we measured susceptibility (χ), electron paramagnetic resonance (EPR), and μSR for ST-LCO, particularly above 100 K. The temperature dependence of χ shows a Pauli paramagnetic behavior, supporting the previous conclusion that Co3+ions are in a low-spin state with S 0 (t62g). However, the EPR and μSR measurements reveal a "dynamical" magnetic phase in ST-LCO above 100 K. Because the volume fraction of this magnetic phase reaches about 50% at 300 K, the appearance of the magnetic phase is not caused by impurities and/or muonium formation but is an intrinsic characteristic of ST-LCO. By considering the time windows of the three measurement techniques used in this study, we conclude that the origin of the dynamical magnetism is most likely spin fluctuations of the Co ions.