Structural, thermodynamic, electrical and dielectric properties of SrZnP2O7 diphosphates compared to SrAII P2O7 (A = Sr and Ni) with analysis of OLPT conduction mechanism

Abstract

A polycrystalline sample of SrZnP₂O₇ was successfully synthesized via the conventional solid-state reaction method. Its structural and vibrational properties were characterized using X-ray powder diffraction (XRD) and infrared (IR) spectroscopy, while its electrical and dielectric properties were investigated through impedance spectroscopy. XRD analysis confirmed the formation of a single-phase compound crystallizing in the monoclinic system with space group P2₁/n. The IR spectrum revealed all the expected vibrational modes associated with the P₂O₇ polyhedral units. Electrical conductivity measurements, carried out over a frequency range of 209 Hz to 1 MHz and a temperature range of 550 K to 711 K, were used to analyze the conduction mechanism. The temperature dependence of the frequency exponent “s” indicated that the conduction in SrZnP₂O₇ follows the overlapping large polaron tunneling (OLPT) model. A strong correlation between the material's structure and its electrical performance was established. Furthermore, comparative analysis with previously reported compounds, Sr₂P₂O₇ and SrNiP₂O₇, demonstrated that SrZnP₂O₇ exhibits superior ionic conductivity, highlighting its promising potential for applications in solid-state ionic devices.