Multiferroic properties of Bi5.75R0.25Fe1.4Ni0.6Ti3O18 (R = Eu, Sm, Nd, Bi and La) ceramics

An improved technique was used to prepare the ceramic samples of Bi5.75R0.25Fe1.4Ni0.6Ti3O18 (BRFNT, R = Eu, Sm, Nd, Bi, and La). The five-layer Aurivillius phase of the samples was confirmed by X-ray diffraction (XRD) without detectable impurities. BRFNT samples exhibit the pseudo-tetragonal except the orthorhombic BSmFNT samples. The characteristic plate-like morphology was revealed by field emission transmission electron microscopy (FETEM) images. At ambient temperature, all the samples present both ferroelectric and magnetic properties and BEuFNT shows the best ferroelectric behavior with its remanent polarization as high as 14.9 mu C/cm(2) under 155 kV/cm, which is three times higher than that of Bi6Fe1.4Ni0.6Ti3O18. Moreover, the remanent magnetization of BEuFNT is increased up to 1.20 emu/g compared to that of Bi6Fe1.4Ni0.6Ti3O18 which is only 0.53 emu/g. With increasing radius of the introduced A-site ions, the ferroelectric phase transition temperature (T-CE) is decreased while the magnetic phase transition temperature (T-CM) fluctuates. The decrease in both T-CE and T-CM corresponds to the upward shift of the related Raman modes and vice versa, indicating that the T-CE and the T-CM depend not only on the t factor, but also on the strength of the covalent bonds. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

Automated summary

An improved technique was used to prepare ceramic samples of Bi5.75R0.25Fe1.4Ni0.6Ti3O18 with a five-layer Aurivillius phase, exhibiting both ferroelectric and magnetic properties. With an increase in the radius of the A-site ions, the ferroelectric phase transition temperature decreases, while the magnetic phase transition temperature fluctuates.