Multifunctional Ferroelectric–Ferromagnetic behavior and high energy storage density in ball-milled nanostructured KNbO3–Bi2O3–Fe2O3 for capacitive energy storage

Abstract

The mixed powders of KNbO 3 , Bi 2 O 3 and Fe 2 O 3 (mixed in a 1:1:1 M ratio) were prepared using the ball mill technique. XRD patterns and HR-TEM at room temperature were investigated. XRD analysis of the samples showed that four phases were present in the formations, which are BiFeO 3 , K 2 FeO 4 , KBi 2 Nb 5 O 16 and Bi 1.82 K 0.18 O 2.82 . Dielectric permittivity was measured for the HT 8h sample as a function of both frequency & temperature. Two dielectric peaks appeared at 313 K and 618 K; the appearance of two dielectric peaks is attributed to the multiphase nature of the ceramic. The low-temperature anomaly (∼313 K) originates from local structural rearrangements and domain-wall dynamics within the perovskite-related ferroelectric network, whereas the high-temperature peak (∼618 K) corresponds to the effective ferroelectric–paraelectric transition near the Curie temperature of the composite system. A variety of electrical properties, including conductivity, modulus, and impedance, were examined throughout a broad frequency range (5 kHz – 1000 kHz) as well as temperature range (296 –675 K). The electric polarization vs. the electric (P–E) hysteresis loop investigations showed a 29.5 J/cm 3 energy storage density at T = 423 K. The results of VSM showed the presence of weak ferromagnetic behavior for TH 8h sample at room temperature. A novel multifunctional material that simultaneously exhibits enhanced ferroelectric and ferromagnetic properties was achieved by combining KNbO 3 and BiFeO 3 . The synergistic interaction between the two components aims to improve both dielectric and magnetic performances, making the composite promising for multifunctional and energy storage applications. Therefore, we believe that the TH 8h sample is a good candidate for applications involving capacitive energy storage.