Larger polarization and weak ferromagnetism in quenched BiFeO3 ceramics with a distorted rhombohedral crystal structure

Abstract

Single-phase insulating BiFeO3 ceramics have been synthesized by a simple but effective method that conventional solid state reaction is followed immediately by quenching processing. At room temperature, the ceramics show a metastable, distorted rhombohedral phase and the refined structure parameters are presented based on x-ray diffraction. It is revealed that the formations of Fe2+ and oxygen deficiency are greatly suppressed by the quenching processing. A well-saturated ferroelectric hysteresis loop with a large remnant polarization (2Pr=23.5μC∕cm2) is observed with an applied field of 155kV∕cm. Temperature-dependent magnetic property is investigated and weak ferromagnetism with a remnant magnetization of 4×10−6μB∕Fe at 10K is established. These results may have implications for further studies on multiferroics.

Microwave synthesis of single-crystalline perovskite BiFeO3 nanocubes for photoelectrode and photocatalytic applications

“…19 The peak at 529.5 eV corresponds to O 2− in the lattice. 20 Similarly, Bi 4f doublet of BiFeO 3 shows peaks at binding energies of 164.1 and 158.8 eV, characteristics of Bi 3+ . 21 BiFeO 3 is a small band gap metal oxide semiconductor useful for visible light active photocatalysis.…”

Processing and properties of Yb-doped BiFeO3 ceramics

“…27, a P s of 20 C/cm 2 was obtained in La-doped BFO ceramics measured under 200 kV/ cm.͒ It is believed that the enhancement in the ferroelectric polarization of the doped ceramics is due to both lattice distortion and leakage current reduction. 7,12,13 Associated with the change of ferroelectric properties, the dielectric properties of the samples were also found to be dependent on the doping level. …”

“…12,13,20,27 ͑For example, in Ref. 13, a P s of 17 C/cm 2 was found in a quenched BFO ceramic tested under 155 kV/ cm and in Ref. 27, a P s of 20 C/cm 2 was obtained in La-doped BFO ceramics measured under 200 kV/ cm.͒ It is believed that the enhancement in the ferroelectric polarization of the doped ceramics is due to both lattice distortion and leakage current reduction.…”

“…These results are comparable to the enhanced polarizations of modified BFO bulk ceramics reported in the literature. 12,13,20,27 ͑For example, in Ref. 13, a P s of 17 C/cm 2 was found in a quenched BFO ceramic tested under 155 kV/ cm and in Ref.…”

“…New processing techniques, such as rapid liquid phase sintering, have been developed to synthesize single-phase BFO ceramics. 12,13 The effect of compositional modification, either by forming of solid solution ͑e.g., with Pb͑Zr 1−x ,Ti x ͒O 3 ͒ 14 or by doping, has also been extensively studied. Quite a number of transition metal elements ͑e.g., Ni, Ti, Cr, and Mn͒ [15][16][17][18] and rare-earth elements ͑e.g., La and Nd͒ 19,20 have been employed as dopants.…”