Dielectric Relaxation Studies of the Fast Lithium-ion Conductor La2/3-xLi3xTiO3 (x=0.06, 0.11)
The diffusion processes of lithium ions in La2/3-xLi3xTiO3 (x=0.06, 0.11) compounds were investigated by dielectric relaxation method. Prominent relaxation dielectric loss peaks, peaks P1 and P2 in La0.56Li0.33TiO3 and peaks P3 and P4 in La0.61Li0.18TiO3, were observed. From the shift of peak position with frequency, the activation energy of 0.36×0.42 eV and the pre-exponential factor of relaxation time in the order of 10-14 × 10-13 s were obtained if one assumes Debye relaxation processes. The activation energies of lithium ion diffusion in La2/3-xLi3xTiO3 compounds and the characteristic vibration frequency for the ionic hopping motion are higher than those measured by 7Li nuclear magnetic resonance (NMR) spectroscopy and that of the typical phonon frequency (about 1013Hz). These values of relaxation parameters strongly suggest the existence of interaction between the relaxation species (here lithium ions or vacancies). Basing on the coupling model, the decoupled relaxation parameters of the dielectric relaxation peaks is: P1 (0.14 eV, 2×10-13 s), P2 (0.25 eV, 1.8×10-13 s), P3 (0.17 eV, 4×10-13 s) and P4 (0.3 eV, 2.7×10-13 s). These decoupled parameters are very close to the NMR measurement results and the reciprocal of the typical phonon frequency. Judging from the relaxation parameter of the peaks and combining with the crystallographic characterization, it is suggested that the P1 (P3) and P2 (P4) peaks are associated with the lithium ion diffusion in the ab planes and between the adjacent ab planes, respectively.
lithium ion conductor lithium ion diffusion dielectric relaxation
Wang Wei Guo Fang Qian Feng Hao Gang Ling
College of Physics and Electronic Information, Yan’an University, Yan’an 716000, P. R. China Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences,
国际会议
沈阳
英文
1019-1024
2011-11-22（万方平台首次上网日期，不代表论文的发表时间）