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

TLDR

The study aims to develop a rapid liquid‑phase sintering process that suppresses Fe²⁺ formation and oxygen deficiency, thereby reducing leakage and enabling synthesis of other multivalent or volatile ceramics. High‑resistivity, single‑phase BiFeO₃ ceramics were fabricated by a rapid liquid‑phase sintering technique employing a very high heating rate, short sintering period, and liquid phase formation. Room‑temperature saturated ferroelectric hysteresis loops were obtained in ceramics sintered at 880 °C for 450 s, exhibiting a spontaneous polarization of 8.9 µC/cm², remnant polarization of 4.0 µC/cm², and coercive field of 39 kV/cm, while the process also increased ceramic density.

Abstract

Single-phased ferroelectromagnet BiFeO3 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 μC/cm2, 4.0 μC/cm2, and 39 kV/cm, respectively, under an applied field of 100 kV/cm. It is proposed that the formation of Fe2+ 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.