Dispersive conductivity and dielectric behavior in niobium based NASICON glasses and analysis using anomalous diffusion model

Ion transport properties of Na2NbZnP3O12, Na2NbCdP3O12, Na2NbPbP3O12, Na2NbCuP3O12 and Li2NbPbP3O12 phosphate glasses were investigated over a frequency range from 100 Hz to 1 MHz at different temperatures. The non-Debye behaviors in real part of ac conductivity and permittivity of these glasses were analyzed using Jonscher's universal power law (UPL), and anomalous diffusion model (ADM). The ADM was used to extract the dc conductivity and the relevant physical parameters, namely, crossover length and relaxation frequency in the ion diffusion process. The dc conductivity extracted from UPL matches well with ADM and hence their activation energy. The electric modulus data were analyzed using the Kohlrausch–Williams–Watts (KWW) stretched exponential function and ADM. The ADM fits superior to the KWW in the high frequency wing of electric modulus.