Synthesis of nonstoichiometric M-type barium ferrite nanobelt by spark plasma sintering method

This study investigated the feasibility of ultrafast crystallization of M-type barium ferrite when the coprecipitation precursors in stoichiometric proportions as BaFe₁₂O₁₉, Fe(OH)₃ and BaCO₃ nanoparticles, had been heated by spark plasma sintering (SPS) process. The results show that SPS method may realize the ultrafast crystallization of M-type barium ferrite, absolutely prevent the crystallization of intermediate phase α-Fe₂O₃, and significantly decrease the crystallization temperature of M-type barium ferrite. The sintered samples obtained at 800 °C by sintering the precursors for 10 minutes are a kind of multiphase ferrites composed of major phase M-type barium ferrite and trace amount of BaFe_0.24Fe_0.76O_2.88. It is discovered that M-type barium ferrites in the holes of the sintered samples are in nanobelt microstructure about 100–300 nm in width and several micrometers in length. These M-type barium ferrite nanobelts are non-stoichiometric and may be expressed as BaFe_12+xO_19+1.5x (−4.77⩽x⩽6.50). Their composistions suggest completely random Fe-rich or Ba-rich domains.