  We report here the realization of ferroelectricity, ferromagnetism and
magnetocapacitance effect in SrFe12O19 ceramics at room temperature. The
ceramics demonstrate a saturated polarization hysteresis loop, two I-V peaks
and large anomaly of dielectric constant near Curie temperature. These
evidences confirmed the ferroelectricity of SrFe12O19 ceramics after annealing
in O2 atmosphere. The remnant polarization of the SrFe12O19 ceramic is 103
{\mu}C/cm2. The material also exhibits strong ferromagnetic characterization,
the coercive field and remnant magnetic moment are 6192Oe and 35.8emu/g,
respectively. Subsequent annealing SrFe12O19 ceramics in O2 not only reveals
its innate ferroelectricity but also improves the ferromagnetic properties
through transforming Fe2+ into Fe3+. By applying a magnetic field, the
capacitance demonstrates remarkable change along with B field, the maximum
relative change of dielectric constant is 1174%, which reflects a giant
magnetocapacitance effect in SrFe12O19. These combined functional responses in
SrFe12O19 ceramics opens substantial possibilities for applications in novel
electric devices.

Materials Science