Synthesis and characterization of BaTi_1−xNb_xO₃ ferroelectric perovskite oxides with tunable band gap, anomalous photovoltage, and enhanced energy storage

In this study, we investigated dense BaTi_1−xNb_xO₃ ceramics prepared by the conventional solid-state reaction technique which shows energy storage properties and anomalous photovoltaic effect. Structural analysis of BaTi_1−xNb_xO₃ compositions has been performed by fitting the XRD patterns with Rietveld method and all samples show coexisting tetragonal (P4 mm) and cubic (Pm-3 m) structures. Composition (x = 0.04) shows minimum band gap (2.4 eV), smaller than pure BaTiO₃ ceramics which can be attributed to lattice distortion and oxygen vacancies. The improved breakdown strength and energy storage density is achieved for BaTi_0.93Nb_0.07O₃ composition. This ferroelectric ceramic shows energy storage of 278.7 mJ/cm² and high energy conversion efficiency (90.4%). The composition (x = 0.07) exhibit a very high photovoltage (26 V) under visible light wavelength. These findings provide a fresh approach to create high-performance functional ferroelectric materials for energy applications.