Properties Of BiFeO3 Ceramics Research Articles

Effect of co-substitution of Na0.5Bi0.5TiO3 and CaTiO3 on the structure and properties of BiFeO3 ceramics

Effect of co-substitution of Na0.5Bi0.5TiO3 and CaTiO3 on the structure and properties of BiFeO3 ceramics

Effect of Co-Substitution of Na0.5bi0.5tio3 and Catio3 on the Structure and Properties of Bifeo3 Ceramics

Effect of Co-Substitution of Na0.5bi0.5tio3 and Catio3 on the Structure and Properties of Bifeo3 Ceramics

Impact of (Pr, Dy) Co-doping at Bi Site on Optical and Multiferroic Properties of BiFeO3 Ceramics Prepared by Sonochemical Method

Impact of (Pr, Dy) Co-doping at Bi Site on Optical and Multiferroic Properties of BiFeO3 Ceramics Prepared by Sonochemical Method

Influence of La doping on multiferroic properties of BiFeO3 ceramics prepared by the melt-quenching method

Influence of La doping on multiferroic properties of BiFeO3 ceramics prepared by the melt-quenching method

Effects of Bi2O3–B2O3–ZnO glass additive on structure, ferroelectric and dielectric properties of BiFeO3 ceramics

Lead-free BiFeO3 ceramics doped with varying amounts of Bi2O3–B2O3–ZnO (BBZ) glass, that is, x wt% (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were prepared via the traditional solid-state reaction route. The effects of BBZ glass content on the phase composition, microstructure, dielectric, and ferroelectric properties of BiFeO3 ceramics were investigated. X-ray diffraction results confirmed that BBZ glass doping increased the formation of secondary phases (Bi2Fe4O9 and Bi25FeO39). Scanning electron microscopy images showed that the samples with the addition of BBZ glass showed a heterogeneous size distribution of grains and more porosity. With the increase of the BBZ glass content, the fluctuation of Fe-ions was decreased and the bond strength of the Bi-O was increased. The samples with BBZ glass addition showed smaller dielectric constant and more saturated polarization hysteresis loops compared with pure BiFeO3. The Curie temperature (TC) decreased gradually from 825.8 °C for x = 0.0 to 637.0 °C for x = 2.0. In addition, leakage current density decreased with the addition of BBZ glass. These changes of the electric properties were related to the heterogeneous size distribution of grains, the generation of secondary phases and the increase of the concentration ratios of Fe3+ and Fe2+ in BiFeO3-xBBZ samples.

Combined experimental and theoretical investigation on modulation of multiferroic properties in BiFeO3 ceramics induced by Dy and transition metals co-doping

Multiferroic Dy and transition metals (Cr, Mn, Ni) co-doped BiFeO3 ceramics were successfully synthesized by a solid-state method, and the influence on the magnetic and ferroelectric properties were investigated. Compared with Bi0.95Dy0.05Fe0.95Mn0.05O3, Bi0.95Dy0.05Fe0.95Cr0.05O3 and Bi0.95Dy0.05Fe0.95Ni0.05O3 ceramics can significantly improve the magnetic properties. The significant enhancement of magnetic properties should be related to the local ferromagnetic coupling from Cr ions (Ni ions) and Fe ions, which have already been proved by first-principles calculations. Meanwhile, both experimental and theoretical studies reveal the Dy substitution can effectively enhance the ferroelectric properties of BiFeO3. Leakage current and conduction mechanism analyses reveal that the improved ferroelectric properties are mainly attributed to the reduced oxygen vacancies.

Au5+ ion implantation induced structural phase transitions probed through structural, microstructural and phonon properties in BiFeO3 ceramics, using synergistic ion beam energy

ABSTRACTImplanted Au5+-ion-induced modification in structural and phonon properties of phase pure BiFeO3 (BFO) ceramics prepared by sol–gel method was investigated. These BFO samples were implanted by 15.8 MeV ions of Au5+ at various ion fluence ranging from 1 × 1014 to 5 × 1015 ions/cm2. Effect of Au5+ ions’ implantation is explained in terms of structural phase transition coupled with amorphization/recrystallization due to ion implantation probed through XRD, SEM, EDX and Raman spectroscopy. XRD patterns show broad diffuse contributions due to amorphization in implanted samples. SEM images show grains collapsing and mounds’ formation over the surface due to mass transport. The peaks of the Raman spectra were broadened and also the peak intensities were decreased for the samples irradiated with 15.8 MeV Au5+ ions at a fluence of 5 × 1015 ion/cm2. The percentage increase/decrease in amorphization and recrystallization has been estimated from Raman and XRD data, which support the synergistic effects being operative due to comparable nuclear and electronic energy losses at 15.8 MeV Au5+ ion implantation. Effect of thermal treatment on implanted samples is also probed and discussed.

Effect of Multiple Substitutions (Pb, Ti, Zr) on Structural, Permittivity and Electrical Properties of BiFeO3 Ceramics

Three complex polycrystalline samples of Bi1-xPbxFe1-x Zrx-yTiyO3,with the combination of (i) x, y = 0.0 (BFO), (ii) x = 0.5 and y = 0.5 (BFPTO)and (iii) x = 0.5 and y = 0.25 (BFPZTO) were prepared by a standard mixed oxide (solid state reaction route) method at optimized calcinations (900oC) and sintering (930-950oC)temperatures. The effect of multiple (Pb, Ti and/or Zr) substitutions of different amount onthe permittivity, impedance and modulus characteristics of the materials has been investigated at different frequencies and temperature.Limitation associated with BiFeO3 (BFO) due to its semiconducting behavior acts as constraint in polling the material at room temperature leading to large dielectric loss. Attempts were made to minimizethe loss by substitution of Pb on the Bi site and Ti and/or Zr at the Fe site of BFO. The study indicates that the phase transition temperature of BFO is lowered,the degree of diffuse phase transition is enhanced and electrical parameters (dielectric constant, electrical resistivity, remnant polarization and maximum polarization) areincreased with a significant reduction in dielectric loss as a consequence of the substitution. Detailed studies of Nyquist plots with impedance and electric modulus data suggest that the existence of non-Debye type of relaxation phenomena in the materials. The ac conductivity study reveals that the conduction mechanism in the material obeys universal Jonscher’s power law.

Effects of Ba-doping and process conditions on the structure and magnetic properties of BiFeO3 ceramics

Multiferroic Bi1-xBaxFeO3 (named as BBFO-x, x=0, 0.05, 0.15) are prepared by the sol-gel method through rapid thermal process. The effects of Ba-doping and process conditions on the structures and magnetic properties of the samples are investigated. The experimental results indicate that the process requirements of the pure BBFO-x samples are rigorous. The samples annealed at 800 ℃ for 450 s possess the best structures and magnetic properties. X-ray diffraction results show that Ba-doping causes lattice deformations, but does not change the macroscopic lattice structures of the samples, which is further proved by the Raman spectra of the samples. Besides, Ba-doping is beneficial to enhancing the magnetization of the sample, which is attributed to both the destruction of long-rang antiferromagnetic spiral magnetic structure and the possible spin coupling resulting from the valent state change of the Fe ions. These achievements provide experimental foundation for further studying the microstructure and magnetoelectric coupling effect in such single phase multiferroics.

Effects of Process Parameter and Excess Bi2O3 on Phase Formation and Electrical Properties of BiFeO3 Ceramics

The BiFeO3 was prepared by a mixed oxide, solid-state reaction method. Excess Bi2O3 (1–7wt%) was introduced prior to powder calcination to compensate for any Bi2O3 that may have been lost from the samples due to volatilization during heat treatments. Various heating rates (1–10°C/min) were performed at the calcination state. X-ray diffraction analysis revealed that pure phase BFO was observed for the samples calcined at a low heating rate (1°C/min) and contained lower amount of Bi2O3.The higher levels of excess Bi2O3 produced an increased in dielectric constant and dielectric loss. Further, ferroelectric behavior was improved for higher amount Bi2O3 contented samples.

Preparation and Characteristics of BiFeO<sub>3</sub> Ceramics Doped by MnO<sub>2</sub> and Co<sub>2</sub>O<sub>3</sub>

BiFeO3-based single-phase multiferroics have been widely studied in both ceramics and films. However, the macroscopic magnetic properties of BiFeO3 ceramics were now most very weak. In this work, MnO2 and Co2O3 were used as B-site substitutes in BiFeO3 ceramics in order to the enhancement of magnetic properties. The change of magnetization was analyzed based on the phase composition and the microstructure of ceramics.