Study on morphological, FTIR, optical band-gap and AC conductivity of Li2CoP2O7 for advanced applications

Abstract

Lithium diphosphates, and particularly Li₂CoP₂O₇, have garnered increasing attention due to their promising properties for applications in energy storage and electronic devices. In the present study, Li₂CoP₂O₇ was successfully synthesized using a conventional solid-state reaction route. X-ray powder diffraction (XRD) analysis confirmed the formation of a pure monoclinic phase with C2/c space group symmetry and an average grain size of approximately 2.66 μm. Infrared (IR) spectroscopy revealed distinct vibrational modes characteristic of P₂O₇⁴⁻ groups, in line with the expected structural framework. Optical absorption measurements indicated that the material exhibits semiconducting behavior, with an estimated indirect band gap of approximately 3.78 eV. Dielectric studies demonstrated that Li₂CoP₂O₇ possesses excellent dielectric performance, including a remarkably high dielectric constant (∼2 × 10⁸), suggesting its suitability for low-frequency energy storage applications. Impedance spectroscopy measurements revealed a non-Debye relaxation mechanism, with temperature-dependent relaxation dynamics analyzed using the Arrhenius model. Furthermore, the frequency-dependent ac conductivity followed Jonscher's universal power law, and the behavior of the frequency exponent s was consistent with the correlated barrier hopping (CBH) conduction model. Overall, these findings offer valuable insights into the dielectric relaxation processes and charge transport mechanisms in Li₂CoP₂O₇, underscoring its potential for high-performance applications in advanced electronic systems and energy storage technologies.