Impact of platinum doping on the structural, cation distribution, electrical and dielectric properties of CoZn nanospinel oxides

This study explores the structural and electrochemical properties of Pt-doped cobalt–zinc nanospinel oxides (Co_0·5Zn_0·5Pt_3xAl_2-4xO₄ NSOs, 0.00 ≤ x ≤ 0.10) synthesized via a sol–gel combustion route, with a focus on tunable electrical behavior for energy-related applications. Phase-pure spinel formation was confirmed by XRD, while SEM/EDX analyses verified nanoscale morphology and composition. Systematic investigation of frequency- and temperature-dependent conductivity, dielectric, and impedance responses revealed that moderate Pt substitution (x ≈ 0.02–0.06) significantly enhances charge mobility through defect-assisted transport, while higher substitution levels introduce additional relaxation phenomena and interfacial polarization. Modulus and Cole–Cole analyses confirmed a transition from Debye-to non-Debye-type relaxation, indicating a compositional control of grain and grain boundary contributions. These findings demonstrate that Pt doping provides a strategy for tuning electrical heterogeneity and dielectric response in CoZn–Al spinels, making them promising candidates for energy storage devices and sensing applications.