Room-temperature saturated ferroelectric polarization in BiFeO3 ceramics synthesized by rapid liquid phase sintering

Single-phased ferroelectromagnet ${\mathrm{BiFeO}}_3$ ceramics with high resistivity were synthesized by a rapid liquid phase sintering technique. Saturated ferroelectric hysteresis loops were observed at room temperature in the ceramics sintered at 880 °C for 450 s. The spontaneous polarization, remnant polarization, and the coercive field are 8.9 $\mu {\mathrm{C/cm}}^2,$ 4.0 $\mu {\mathrm{C/cm}}^2,$ and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of ${\mathrm{Fe}}^{\text{2+}}$ and an oxygen deficiency leading to the higher leakage can be greatly suppressed by the very high heating rate, short sintering period, and liquid phase sintering technique. The latter was also found effective in increasing the density of the ceramics. The sintering technique developed in this work is expected to be useful in synthesizing other ceramics from multivalent or volatile starting materials.