The evolution of microstructure, magnetic, and electrical properties of a theoretically predicted Sr3NiNbO7-δ (SNNO) perovskite synthesized by modified sol–gel technique is investigated for the first time. Rietveld refinement of XRD pattern reveals a double-layered Ruddlesden-Popper (RP) phase with I4/mmm space group of tetragonal structure. XPS analysis confirms Sr2+ and Nb5+ oxidation states, Ni exists as Ni2+ and Ni3+, accompanied by oxygen vacancies. A detailed analysis of thermomagnetic behavior reveals an antiferromagnetic interaction between Ni2+ and Ni3+, with an effective magnetic moment of 3.75 \({\mu }_{B}\) , confirmed from the fitting of χ−1 vs T with the modified Curie–Weiss law. Again, the isothermal magnetization loop discloses a second order magnetic transition using the Arrott plot for various temperatures and a weak ferromagnetic contribution in low field regions at room temperature induced by the exchange interaction between spin polarized magnetic ions mediated by oxygen. The frequency dependent ac conductivity at various temperatures (50–440 °C) within the frequency range of 1 Hz to 1 MHz reveals the conduction described by two mechanisms i.e. correlated barrier hopping (CBH) below 170 °C, and nonoverlapping small polaron tunneling (NSPT) above 170 °C. Further, an increasing trend of conductivity, with the highest conductivity of 1.7 \(\times\) 10–4 S cm−1 observed at 440 °C from electrical impedance spectroscopy (EIS) method, confirms the semiconducting nature of the sample. The newly synthesized SNNO can be used to develop energy-efficient materials for applications in fuel cells and advanced electronic devices.
