NMR Study of LiCo_1-xCr_xO₂and Li_1-xNa_xCoO₂(x=0and 0.05)

Frustrated magnetism in the two-dimensional triangular lattice of

“…For LiCoO 2 , as T decreases from 300 K, N A TF is constant at its maximum value ð$1Þ down to 50 K, indicating that the sample volume is 100% paramagnetic. Then, N A TF drops at 50 K with further decreasing T, and N A TF $0:8 at 1.8 K. This indicates the existence of a magnetic transition with an onset temperature T on c $50 K and a transition width DT$30 K in LiCoO 2 with volume fraction of the magnetic phase ðV F Þ roughly estimated as $20% even at 1.8 K. Interestingly, the transition around 50 K is not detected by w and NMR experiments [11].…”

“…It is thus believed that LiCoO 2 does not exhibit magnetic transitions at low T. This was also confirmed by w and NMR experiment down to 4.2 K [11]. Although LiCoO 2 is known to be an insulator, Li deficient Li x CoO 2 with x ¼ 0:7-0.55, in which Li was removed/deintercalated by an electrochemical reaction similar to Li batteries, exhibits metallic behavior above 50 K [12].…”

Electron correlation in the two-dimensional triangle lattice ofNaxCoO2

“…The structure of LiCoO 2 is isomorphous with α-NaFeO 2 (R3m) [29] and almost the same structure as that of the γ-Na x CoO 2 phase, if we ignore the difference of the occupancy between the Na and the Li plane. LiCoO 2 is reported to be diamagnetic down to 4.2 K. [30] Since the Co 3+ ions in LiCoO 2 are in a low-spin state t…”

A novel tool for detecting Li diffusion in solids containing magnetic ions;μ+SR study on LixCoO2

“…Such difficulty was clearly evident in the 1/T 1 (T ) curve for LiCoO 2 and LiNiO 2 [3,4], and, for that reason, D Li was instead estimated from the Li-NMR line width [5]. However, since the line width, i.e., the spin-spin relaxation rate (1/T 2 ) is also affected by the magnetic ions, the D Li obtained by Li-NMR for LiCoO 2 (= 1 × 10 −14 cm 2 s −1 at 400 K) is approximately four orders of magnitude smaller than predicted by first-principles calculations [6].…”