Temperature‐Driven Electrical Relaxation and Dielectric Functionality in Fe‐Substituted in Pr‐Based Manganite

ABSTRACT

The monovalent doping of Pr _0.75 Na _0.05 K _0.20 Mn _0.97 Fe _0.03 O ₃ manganite was systematically investigated to elucidate the interplay between crystal structure correlations through X‐ray diffraction, impedance response, conductivity, dielectric properties, and electric modulus analyses over the temperature range 303–373 K. X‐ray diffraction confirms the formation of a single‐phase perovskite structure, indicating successful incorporation of Fe ^{3 +} at the Mn site. Impedance spectroscopy reveals thermally activated non‐Debye relaxation dominated by grain boundary effects, as evidenced by depressed semicircular Nyquist plots and reduced resistive contributions at elevated temperatures. The frequency‐dependent AC conductivity follows Jonscher's universal power law, with the Non‐Overlapping Small Polaron Tunnelling (NSPT) mechanism being the dominant conduction process. Dielectric measurements show enhanced permittivity at low frequencies due to Maxwell–Wagner interfacial polarization, while dielectric loss decreases significantly at higher frequencies, reflecting improved energy efficiency. Electric modulus formalism highlights bulk relaxation processes, with M′  exhibiting low‐frequency suppression and M′′ showing temperature‐dependent relaxation peaks shifting toward higher frequencies. These features are attributed to small polaron hopping modulated by Fe‐induced lattice distortion and charge carrier localization. The combined electrical response demonstrates that controlled B‐site substitution effectively tunes relaxation dynamics and dielectric functionality in Pr‐based manganites, making them promising candidates for advanced electronic and sensing applications.