Structural, Electrical, and Magnetic Properties of Mullite-Type Ceramic: Bi 2 Fe 4 O 9

Abstract

This work reports the structure, electrical and magnetic properties of the ortho-rhombic (Pbam) structured bulk Bi 2 Fe 4 O 9 synthesized by the solid-state reaction process. Bi 2 Fe 4 O 9 has been studied using several experimental techniques such as X-ray diffraction, scanning electron microscopy, Raman spectroscopy, dielectric spectroscopy, and magnetometry. Rietveld-refined X-ray diffraction data and Raman spectroscopy results clearly reveal the formation of Bi 2 Fe 4 O 9 perovskite structure and all the peaks of Bi 2 Fe 4 O 9 perfectly indexed in the orthorhombic (Pbam) structure. It has been established that the Raman spectrum identified A g , B 2g , and B 3g active optical phonon modes, and that the Raman peak at 470 cm −1 may have a magnetic origin. As a result, the coexistence of weak ferromagnetic and antiferromagnetic orders in Bi 2 Fe 4 O 9 ceramic was established. The remanent magnetization (2M r) and coercivity (2H c) are 8.74 × 10 −4 emu/g and 478.8 Oe, respectively. We report a remarkable multiferroic effects in polycrystalline Bi 2 Fe 4 O 9 ceramic. These characteristics make this material very useful in technology and practical applications.