Effect of Ni Substitution on Structural, Magnetic and Dielectric Properties of KBiFe2O5

Abstract

The influence of Ni substitution on structural, magnetic and dielectric properties of potassium bismuth ferrite (KBiFe2O5) are investigated. Polycrystalline samples of KBiFe2.xNixO5 (x = 0, 0.01, 0.05) are synthesized by solid state reaction method. For the phase purity of the samples X-ray diffraction is carried out. Based on the refinement results, all the samples are found to be crystallized in monoclinic structure with P2/c space group without any structural transformation. Average grain size of the samples is calculated to be in between 1 – 2 μm using SEM analysis and slightly decreases with Ni substitution. Chemical composition is confirmed by energy dispersive X-ray spectroscopy. XPS analysis confirms that both Ni and Fe exists in +3 oxidation state. From M-H hysteresis loop, it is observed that pure sample shows weak ferromagnetic behavior whereas, Ni substituted compounds show ferromagnetic like behavior with enhanced magnetic moment compared to pure compound. The maximum magnetization increases from 0.12 emu/gm to 0.76 emu/gm and tends to saturate with Ni substitution. Temperature dependent magnetic data depicts that magnetization increases with increase in temperature but with Ni substitution, magnetization shows a decreasing order with increasing temperature. Temperature dependent dielectric constant (ε) for all samples are investigated over a temperature range of 300 K – 773 K. The ferroelectric to paraelectric transition is appeared at around 750 K for KBiFe2O5. The appearance of magnetic transition in dielectric vs temperature curves give an indirect interpretation of magnetoelectric coupling. Modified KBiFe2O5 seems to be a promising candidate for data storage and energy storage application