Dielectric relaxation behavior induced by lithium migration in Li4Ti5O12 spinel

The microstructure, crystal structure and electrical properties of polycrystalline spinel Li4Ti5O12 (LTO) were studied. The Rietveld refinement of the XRD pattern of LTO shows a cubic phase with the space group Fd (3) over barm. Three dielectric relaxations associated with Li+ ion diffusion through different paths are clear in the temperature dependence of dielectric properties. The relation between dielectric response and local structure is revealed by an in situ Raman spectroscopy. The variation of beta in the KWW function is related to the migration of Li ions, which is in agreement with the universal response law (URL). The scaling behavior of the imaginary part of the electric modulus indicates that three relaxation processes have the same mechanism at each selected temperatures. Combined with impedance and modulus spectra, an insight into the transportation behavior of Li+ at different chemical environments is obtained, meanwhile, it provides an effective tool to probe the relationship between diffuse pathway of lithium ion and dielectric response. (C) 2019 Elsevier B.V. All rights reserved.