Mullite‐hexagonal di‐phase multiferroic behavior with enhanced ferromagnetism of (1−x)Bi2Fe4O9−xBaFe12O19 composites

Abstract

Multiferroic (1−x)Bi2Fe4O9−xBaFe12O19 (x = 0.07, 0.08, 0.10, 0.12, 0.15, 0.20) composites were prepared using microwave hydrothermal and microwave sintering methods. X‐ray diffraction analysis of the composites revealed the formation of di‐phase compounds with barium hexaferrite and mullite bismuth ferrite, respectively. SEM (scanning electron microscope) measurements on the sintered surfaces of the composites displayed the micro‐sized of Bi2Fe4O9 matrix and nano‐sized BaFe12O19. The study of Dielectric and complex impedance exhibited the presence of grain and grain boundary effects, and a negative temperature coefficient of resistance in the materials. The ferroelectric hysteresis loops showed an obvious ferroelectric behavior. The Mr was up to 19.09 emu g−1 (much larger than pure Bi2Fe4O9 matrix), indicating that increasing BaFe12O19 content could enhance the ferromagnetic properties. The value of Mr/Ms for all the samples was higher than 0.5 (especially, the maximum was up to 0.89) and it is preferred in many applications such as magnetic recording media of high density and permanent magnets.