Doping strategies for increased performance in BiFeO3 (original) (raw)
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Ferroelectrics, 2018
Multiferroic materials with magnetoelectric properties, due to their coupling between the electrical and magnetic properties have attracted the attention of many researchers. Perovskite structured materials based on BiFeO 3 are a class of materials largely considered in these studies. In this work, Bi 1-x Nd x Fe 0.99 Co 0.01 O 3 (x ¼ 0.05, 0.10 and 0.20) compositions were synthesized aiming a better understanding of the crystal and electronic structure role in ferroic properties of these materials. Structural studies were made by X-ray diffraction and Rietveld refinement; evidencing the rhombohedral symmetry of the samples with space group R3c. Electron density calculations were performed by the maximum entropy method. These studies showed that Nd 3þ substitution causes distortions in the unit cell, which have influence on the magnetic properties. Also, the electron density maps showed the bonds between the iron and oxygen ions did not changed a lot. But the Minimum Electron Density observations were enough to conclude that the ferroelectric and the dielectric properties of Bi 1-x Nd x Fe 0.99 Co 0.01 O 3 compositions would be modified with the Nd 3þ substitution.
Integrated Ferroelectrics BiFeO 3 : A Review on Synthesis, Doping and Crystal Structure
BiFeO 3 , 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 BiFeO 3 . Special attention is put on obtaining and sintering bulk BiFeO 3 ceramics and the effect of doping on the electric and magnetic properties.
BiFeO3: A Review on Synthesis, Doping and Crystal Structure
Integrated Ferroelectrics, 2011
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.
Magnetic and Dielectric Studies on Cobalt Substituted BiFeO3
2015
This thesis presents the study of structural, surface morphology, electric, magnetic, magnetoelectric and magnetodielectric properties of Cobalt substituted multiferroic BiFeO3. Since their discovery, multiferroics have brought tremendous interest among the researchers due to the coexistence of various ferroic order parameters. The synchronization of the magnetic and electric order parameter, hence generating magnetoelectric coupling, has been of importance in particular. Various functional devices aiming at the coupling between the ferroelectric and ferromagnetic order parameter are underway. Among all, the perovskite oxides (ABO3) based multiferroics are of prime interest due to their ease of synthesis and easy to understand physical interactions due to their simple structure. Bismuth Ferrite (BiFeO3), is a prototype ABO3 type multiferroic material, possessing the ferroelectric Curie temperature (Tc) ~ 1103K and antiferromagnetic Neel temperature (TN) ~ 643K. It exhibits a weak ne...
Temperature dependence of the crystal and magnetic structures of BiFeO 3
Journal of Physics C: Solid State Physics, 1980
The temperature dependence of structural and magnetic order parameters of ferroelectric-antiferromagnetic BiFeO, with rhombohedral perovskite structure is investigated by means of neutron diffraction on a powder sample. The tilt angle of oxygen octahedra decreases from 125" at 4.2 K to 11.4" at 878 K. Associated with ferroelectricity the cation displacements diminish essentially with increasing temperature. Changes of cation shifts, tilt angle, distortion and strain of octahedra are discussed with respect to phase transitions observed by Polomska. Except for the lower Nkel temperature determined by neutron diffraction the temperature dependence of the sublattice magnetisation with saturation moment (gS = 4.34(5)) is in good agreement with Mossbauer results of Biaauw and van der Woude.
Weak ferromagnetism in diamagnetically-doped Bi1−xAxFeO3 (A=Ca, Sr, Pb, Ba) multiferroics
Materials Letters, 2008
Investigation of crystal structure, magnetic and local ferroelectric properties of the diamagnetically-doped Bi 1 − x A x FeO 3 (A = Ca, Sr, Pb, Ba; x = 0.2, 0.3) ceramic samples has been carried out. It has been shown that the solid solutions have a rhombohedrally distorted perovskite structure described by the space group R3c. Piezoresponse force microscopy data have revealed the existence of the spontaneous ferroelectric polarization in the samples at room temperature. Magnetization measurements have shown that the magnetic state of these compounds is determined by the ionic radius of the substituting elements. A-site substitution with the biggest ionic radius ions has been found to suppress the spiral spin structure of BiFeO 3 and to result in the appearance of weak ferromagnetism. The magnetic properties have been discussed in terms of doping-induced changes in the magnetic anisotropy.
Temperature Dependent Magnetic, Dielectric Studies of Sm-Substituted Bulk BiFeO3
Journal of Superconductivity and Novel Magnetism, 2011
Bismuth ferrite-(BiFeO 3) ceramic is the most studied and attractive multiferroic material with low magnetization, moderate leakage current, and low polarization. Samarium substituted bulk BiFeO 3 prepared at low synthesis temperature ∼600°C by the sol-gel process. Room temperature X-ray diffraction (XRD) patterns confirmed the formation of perovskite structure Bi 0.9 Sm 0.10 FeO 3 (BSFO) phases. Present compositions possess high dielectric constant (ε ≈ 199) and low dielectric loss (tan δ ≈ 0.009) at room temperature for 100 Hz frequency. Room temperature dielectric permittivity and dielectric loss decreased with increasing frequency from 100 Hz to 10 MHz. As the temperature increased, an enormous increase in both dielectric permittivity and dielectric loss is observed at all frequency regions. Temperature dependent M-H hysteresis loops were saturated. Spin glass-like ferromagnetic behavior is retained in M-H hysteresis loops measured from the low temperature region and normal ferromagnetic behavior is observed in the high temperature region, both at room temperature and above ∼ 350 K, 400 K, respectively. The origin of the ferromagnetic property in BSFO may be due to the presence of rare earth metal ions at the lattice sites of BFO.
Effect of Ni substitution on the crystal structure and magnetic properties of BiFeO3
Journal of Alloys and Compounds, 2013
In this paper, BiFe 1Àx Ni x O 3 (x = 0, 0.05, 0.10, 0.15, 0.20, and 0.25) nanoparticles were synthesized by a solgel process X-ray diffraction (XRD), and Raman technique analysis showed that a rhombohedrally distorted BiFeO 3 structure with compressive lattice distortion induced by the Ni substitution at Fe sites. Superconducting QUantum Interference Device (SQUID) results showed that, compared with BiFeO 3 prepared under similar conditions, the magnetic properties were significantly enhanced at room temperature. The enhanced ferromagnetism was attributed to the size confinement effect of the nanostructures, the ferromagnetic exchange between the neighboring Fe 3+ and Ni 3+ ions, and the changing of the Fe-O-Fe bond angle. Superparamagnetism with blocking temperature of 10 K for BiFe 0.95 Ni 0.05-O 3 , 75 K for BiFe 0.85 Ni 0.15 O 3 , 125 K for BiFe 0.80 Ni 0.20 O 3 , and 200 K for BiFe 0.75 Ni 0.25 O 3 was also observed.
NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020
We hereby report synthesis and characterizations of BiFeO3 (BFO), Bi0.9La0.1FeO3 (BLFO), Bi0.9La0.1Fe0.9Zn0.1O3 (BLFZO) perovskites. The influence of doping La 3+ at Bi-site and Zn 2+ at Fe-site are investigated in addition to the impurity phases appearing in the synthesized samples. We characterized these samples with X-ray diffraction (XRD) technique to disclose crystal structure acquired. The calculated lattice parameters for BFO, BLFO and BLFZO phases witness the presence of trigonal structure with little variations attributed to varied ionic size of host and guest site ions. The average crystallite size calculated from characteristic peak for BFO, BLFO and BLFZO ceramics were 59.33nm, 81nm and 67.20 nm respectively. From the study of the dielectric nature of these ceramics, it was found that that BLFO exhibits high dielectric constant compared to BFO and BLFZO samples. The loss values of all the samples reported was found relatively very low. The low dielectric constant of BFO and BLFZO in comparison to BLFO can be attributed to the presence of impurity phase with larger fractional percentage. The ac Conductivity study reveals the dc current contribution up to certain field value but in the higher region of applied field, the ac contribution overshadows dc current.