Analysis of the Sr2GdTi2Nb3O15 ceramic: Investigation into its structural properties and complex impedance spectroscopy

In this study, we successfully synthesized tetragonal tungsten bronze with the nominal formula Sr₂GdTi₂Nb₃O₁₅ and systematically examined of its structure, dielectric, and electrical properties. The material was synthesized through the solid-state reaction technique at a temperature of 1350 °C. The formation of the tetragonal tungsten bronze in the P4/mbm space group was verified via Rietveld refinement using X-ray diffraction data. The electrical characteristics of the ceramic were examined using non-destructive complex impedance spectroscopy (CIS) across a range of frequencies (10–10⁶ Hz) at various temperatures. The real component of impedance (Z') displayed a decrease with rising frequency, suggesting a negative temperature coefficient of resistance (NTCR) for this sample. The Cole-Cole plot of the compound exhibits two semicircles, with the compound's resistance gradually decreasing as the temperature increased. Moreover, the activation energy (E_a) was found to be approximately 0.9 eV, which confirms that oxygen vacancies are responsible for the observed relaxation behavior. Complex modulus analysis confirmed the presence of non-Debye relaxations. These results contribute to a thorough comprehension of the structural and electrical characteristics of Sr₂GdTi₂Nb₃O₁₅, opening avenues for potential applications in diverse electronic devices.