BiFeO3, the paradigm of single-phase multiferroic materials, has potential applications in information storage, sensors and actuators This perovskite has a rhombohedral R3c crystallographic structure and shows a spin-modulated cycloidal magnetic structure with a modulation period of ∼62 nm It reveals magnetoelectric coupling at room temperature However, its low remanent magnetization and relatively important leakage current are the main limitations for possible applications In this review we summarize recent studies on doped BiFeO3 Special attention is put on obtaining and sintering bulk BiFeO3 ceramics and the effect of doping on the electric and magnetic properties

BiFeO3: A review on synthesis, doping and crystal structure

Polycrystalline Bi0.8Sr0.2Fe1 − xTixO3 (x = 0.0, 0.1, 0.2) multiferroics were synthesized via the conventional solid state reaction method. The structure, dielectric relaxation, and magnetic properties of as prepared samples were investigated. The crystal structure examined via XRD and Rietveld analysis confirmed a single phase rhombohedral (space group R3c no. 161) structure. In the Rietveld refinement, good agreement between the observed and calculated pattern was observed. The dielectric response of these multiferroics was analyzed in the frequency range of 10 Hz to 5 MHz at different temperatures. All the samples showed dispersion in dielectric constant (έ) and dielectric loss factor (tan δ) values. The temperature dependence of έ and tan δ showed broad peaks. A reduction in the values of έ and tan δ was observed upon the incorporation of Ti. Magnetic measurements were carried out at room temperature up to a field of 20 kOe. Magnetic hysteresis loops revealed a significant increase in magnetization with Ti substitution. A remnant magnetization (Mr) of 33.428 memu/g and a coercive field (Hc) of 1.724 kOe were observed in the sample with x = 0.2.

Rietveld analysis, dielectric and magnetic properties of Sr and Ti codoped BiFeO3 multiferroic

Effect of structural transition on magnetic and optical properties of Ca and Ti co-substituted BiFeO3 ceramics

http://maglab.iphy.ac.cn/m05website/pdf/2010/jmm322(2010)2251-m05.pdf

Structural and magnetic properties in Bi1−xRxFeO3 (x=0–1, R=La, Nd, Sm, Eu and Tb) polycrystalline ceramics

Investigation of structural, magnetic and optical properties of rare earth substituted bismuth ferrite

Polycrystalline BiFe1−xCrxO3 ceramics with x = 0–1 have been produced via a mixed oxide route. The effects of Cr substitution on the structure and on the electrical and ferroelectric properties of BiFe1−xCrxO3 samples have been studied by performing x-ray diffraction, dc resistivity and dielectric measurements as well as characterizing the polarization-field hysteresis loop. The results indicate that the structure of BiFeO3 can be altered dramatically with a small amount of Cr doping (x = 0.005–0.1). Substitution of Cr for Fe results in large variations in the resistivity of BiFeO3 ceramics. The resistivity of BiFe1−xCrxO3 samples reaches a maximum value of 2 × 1012 Ω cm at x = 0.1, which is about two and a half times higher than that for pure BiFeO3. Doping with 1 mol% Cr increases the dielectric constant and the remnant polarization to four and ten times, respectively, as large as those of a pure sample. There is a strong correlation between the electrical resisitivity, the dielectric constants and the remnant polarization of BiFe1−xCrxO3 ceramics.

Effect of Cr substitution on the structure and electrical properties of BiFeO3 ceramics

Crystal structure refinement, ferroelectric and ferromagnetic properties of Ho3+ modified BiFeO3 multiferroic material

Crystal structural, dielectrical properties and high temperature magnetic phase transition of Sm1-xCaxFeO3 (x=0–0.3)

In this work we report experimental evidence for the weak high-temperature ferromagnetism in Bi1-xRxFeO3 (R = Dy, Y) compounds by careful characterizations, excluding the possible side-effects from other iron-based impurities. Remarkable saturated magnetic moment was observed in the Y-substituted samples, Bi1-xYxFeO3, which is larger than the moment obtained in Bi1-xDyxFeO3, the Dy-substituted samples with antiferromagnetic background. The physical origin of the weak ferromagnetic transition is discussed and serious lattice distortions have been identified based on the X-ray diffraction and Raman scattering data, although the rhombohedral structure symmetry remains unchanged upon the substitutions. It is believed that the structural distortion suppressed cycloid spin structure is the main factor for the enhanced magnetization in Bi1-xRxFeO3 compounds. Additionally, the Dy3+-Fe3+ antiferromagnetic coupling, which strengthens the antiferromagnetic interaction in Bi1-xDyxFeO3 compounds, acts as the driving force for the magnetic discrepancy between Bi1-xYxFeO3 and Bi1-xDyxFeO3 samples.

G.L. Song

Papers

Effect of Cr substitution on the structure and electrical properties of BiFeO3 ceramics

Crystal structure refinement, ferroelectric and ferromagnetic properties of Ho3+ modified BiFeO3 multiferroic material

Crystal structural, dielectrical properties and high temperature magnetic phase transition of Sm1-xCaxFeO3 (x=0–0.3)

Enhanced high temperature ferromagnetism in Bi 1-x R x FeO 3 (R = Dy, Y) compounds.