Investigation of Manganese Substitution on Structural and Electrical Characteristics of Bi_0.5K_0.5TiO₃ Ceramics

Abstract

Manganese (Mn)‐modified bismuth potassium titanate, i.e., Bi0.5K0.5Ti1−xMnxO3 (x = 0, 0.05, 0.10, and 0.15), compounds are fabricated by a mixed‐oxide method. The Rietveld analyses of X‐ray diffraction data and the Raman spectroscopy support the formation of the compounds in the tetragonal phase. The crystallite and the grain size are found to be higher for compounds having more oxygen vacancies. With increase in Mn concentration, the bulk resistance decreases drastically and the energy bandgap reduces. The dielectric constant increases substantially with substitution of Mn. The analysis of complex impedance spectroscopy confirms the non‐Debye‐type relaxation mechanisms in the compounds. Based on the activation energy of the conduction process, analysis of leakage current, and energy‐dispersive X‐ray spectroscopy (EDX) data, the ionization of oxygen vacancy and the hopping of trapped electrons between multivalent Ti and Mn ions in electrical properties of the compounds are discussed. The compounds follow the correlated barrier hopping conduction mechanism. While the leakage current in Bi0.5K0.5TiO3 fits the Poole–Frenkel model, that in Mn‐substituted samples exhibits Ohmic conduction mechanism.