Optical, vibrational and complex impedance studies of LiNaSrP2O7 ceramic

Abstract

Due to high stability, safety and energy density properties, solid-state lithium-ion is expected to be used for the next-generation batteries. Recently, new solid electrolyte materials with high-ion conductivity have been widely explored. In this paper, a novel solid electrolyte LiNaSrP2O7 was successfully prepared by the conventional solid-state method and characterized by X-ray diffraction (XRD) analysis, electron microscopy and optical and impedance spectroscopy. XRD and Rietveld analysis show that the sample crystallizes in the orthorhombic structure with Pnma space group. The UV–Vis measurement, performed from 200 nm to 800 nm, show a direct optical band gap evaluated at 5.26 eV. Both impedance and modulus studies reveal the temperature-dependent non-Debye type relaxation conduction phenomenon. AC conductivity has been studied to understand the conduction mechanism. AC conductivity results show the role of quantum mechanical tunneling of charges in the conduction mechanism. Moreover, the electrical conductivity and modulus analysis findings revealed the activation energy obtained from suggests that the transport takes place through the ion hopping mechanism, dominated by the motion of the mixed Li+/Na+ ions in the structure of the investigated material.