Optimization of leakage current response in Mn modified BiFeO3–BaTiO3 near morphotropic phase boundary

Abstract

Compositional variation of BiFeO3 & BaTiO3 materials – having in-equivalent crystallographic symmetry – exhibits unique fertile ground that leads to the structural phase transition from rhombohedral to tetragonal via the realization of morphotropic phase boundary (MPB). The MPB composition exhibit superior piezoelectric and enhanced functional characteristics. Here, we characterize the MPB composition of (1-x)BiFe0.99Mn0.01O3-xBaTiO3 (0.30≤x≤0.32) via X-ray diffraction, impedance spectroscopy, X-ray photoelectron spectroscopy, ferroelectric & electrical leakage measurement to reveal the underlying mechanism. Remarkably, the composition with x = 0.30 shows the lowest leakage current density ∼2.3 × 10−8 A/cm2. This observation reveals the governing role of grain in the assessment of the electrical properties. The pre-factor (A), or polarizability strength and frequency exponent (n), was found by experimental fitting of the conductivity data, which were driven by the Jonscher power law. The overlapping large polaron tunnelling model (OLPT) is linked to the observed decrease in EA values of 0.45 eV, 0.37 eV, and 0.32 eV for x = 0.30, 0.31, and 0.32 solid solutions, respectively. These values indicate the mobility of defects present in the lattice. © 2024 The Authors