Effect of Ba and Y co-doping on the structural and magneto-electric properties of BiFeO 3 ceramic (original) (raw)
Related papers
Dielectric and magnetic properties of Bi1−xYxFeO3 ceramics
Journal of Physics and Chemistry of Solids, 2012
Y doped BiFeO 3 polycrystalline ceramics were prepared by sol-gel method. Crystal structure examined by X-ray diffraction indicates that the samples were single-phase and crystallize in rhombohedral structure. An anomaly in the dielectric constant and dielectric loss in the vicinity of the antiferromagnetic Neel temperature (T N) was observed. Saturated magnetization loops were observed for all sample with saturated magnetization M s ¼ 0.678 emu/g and remnant magnetization M r ¼ 0.084 emu/g for x ¼ 0.3.
Dielectric and Magnetic Properties of Ba(Fe1/2Ta1/2)O3-BiFeO3 Ceramics
Journal of Electronic Materials, 2016
The properties of (1-x)Ba(Fe 1/2 Ta 1/2)O 3-xBiFeO 3 [(1-x)BFT-xBFO] (x = 0.0, 0.1, 0.3, 0.5) ceramics have been investigated. (1-x)BFT-xBFO powders were synthesized by a modified two-step calcination technique, and ceramics were fabricated by a conventional technique. X-ray diffraction (XRD) analysis revealed that the modified ceramics exhibited a mixture of BFT cubic phase and BFO rhombohedral phase. The peaks shift increased with increasing BFO content to a maximum value for the composition with x = 0.5. The overall shift of the XRD patterns indicated distortion of the unit cell, which may be due to ions from BFO entering the BFT lattice. BFO additive promoted grain growth, while the maximum density of the studied ceramics was observed for the x = 0.1 composition. The modified ceramics presented enhanced thermal and frequency stability of the dielectric constant. BFO additive also reduced the loss tangent for the system. Improvement of the magnetic behavior was observed after adding BFO. Furthermore, all the ceramics, including pure BFT (a nonmagnetic phase at room temperature), presented a magnetocapacitance effect, which can be related to magnetoresistance along with Maxwell-Wagner polarization effects.
BiFeO 3 is one of the few single-phase multiferroics, showing antiferromagnetic and ferroelectric ordering. Since the dielectric properties in the ceramic state of the pure BiFeO 3 were rather poor and in order to stabilize the perovskite state and to induce ferromagnetism at room temperature, it was adopted the strategy of doping with rare earth or forming solid solutions. Substituting Fe with Mn in BiFeO 3-based compounds is supposed cause better properties in terms of leakage current density and also to induce changes in the magnetic order of the system. In the present paper, the effect of Mn substitution on the dielectric and magnetic properties of the BiFe 1−x Mn x O 3 ceramics has been studied. Homogeneous samples from microstructural point of view were obtained for all the compositions analyzed. The magnetic properties are strongly affected by the presence of Mn ions. The possible origin of these behavior is discussed in terms of phase purity, grain size and grain boundary phenomena. The extrinsic properties are impossible to be fully controlled by normal ceramic processing. By controlling the extrinsic contributions to the dielectric properties, the ceramic system might be a valuable multiferroic material for magnetoelectric applications. At room temperature the ceramic is a multiferroic, since it is ferroelectric and magnetically-ordered.
Dielectric and Magnetic properties of (1 À x)BiFeO 3 –xBa 0.8 Sr 0.2 TiO 3 ceramics
The polycrystalline samples of (1 À x)BiFeO 3 -xBa 0.8 Sr 0.2 TiO 3 (x = 0, 0.1, 0.2, 0.25, 0.3, 0.4 and x = 1) were prepared by the conventional solid state reaction method. The effect of substitution in BiFeO 3 by Ba 0.8 Sr 0.2 TiO 3 on the structural, dielectric and magnetic properties was investigated. X-ray diffraction study showed that these compounds crystallized at room temperature in the rhombohedral distorted perovskite structure for x 0.3 and in cubic one for x = 0.4. As Ba 0.8 Sr 0.2 TiO 3 content increases, the dielectric permittivity increases. This work suggests also that the Ba 0.8 Sr 0.2 TiO 3 substitution can enhance the magnetic response at room temperature. A remanent magnetization M r and a coercive magnetic field H C of about 0.971 emu/g and 2.616 kOe, respectively were obtained in specimen with composition x = 0.1 at room temperature. #
Dielectric and magnetic properties in Ta-substituted BiFeO3 ceramics
Journal of Materials Research, 2007
The dielectric and magnetic properties were investigated in Ta-substituted BiFeO 3 polycrystalline ceramics synthesized by a solid-state reaction. The Ta substitution decreased the grain size by two orders of magnitude compared with that of unsubstituted ceramics and increased the electrical resistivity by 6 orders of magnitude. The high resistivity and low dielectric loss allowed the dielectric constant to be determined at room temperature. The magnetic hysteresis loops were observed in the Ta-substituted BiFeO 3 , and the appearance of ferromagnetism was closely associated with the distortion of the oxygen octahedra by the Ta substitution. The coupling between the electric and magnetic dipoles was examined by determining the changes of the dielectric constant with the external magnetic field.
Dielectric and Magnetic properties of (1−x)BiFeO3–xBa0.8Sr0.2TiO3 ceramics
Ceramics International, 2012
The polycrystalline samples of (1 À x)BiFeO 3-xBa 0.8 Sr 0.2 TiO 3 (x = 0, 0.1, 0.2, 0.25, 0.3, 0.4 and x = 1) were prepared by the conventional solid state reaction method. The effect of substitution in BiFeO 3 by Ba 0.8 Sr 0.2 TiO 3 on the structural, dielectric and magnetic properties was investigated. X-ray diffraction study showed that these compounds crystallized at room temperature in the rhombohedral distorted perovskite structure for x 0.3 and in cubic one for x = 0.4. As Ba 0.8 Sr 0.2 TiO 3 content increases, the dielectric permittivity increases. This work suggests also that the Ba 0.8 Sr 0.2 TiO 3 substitution can enhance the magnetic response at room temperature. A remanent magnetization M r and a coercive magnetic field H C of about 0.971 emu/g and 2.616 kOe, respectively were obtained in specimen with composition x = 0.1 at room temperature.
Ferroelectrics, 2018
The composite 0.75(1-x)BiFeO 3-xBaTiO 3-0.25BaZr 0.4 Ti 0.6 O 3 or 0.75(BFO-BTO)-0.25BZT ceramics (x ¼ 0.23-0.27) have been prepared by solid state reaction method to studied the relationship between phase formation, dielectric and magnetic properties. The results found that the phase formations of calcined BFO-BTO and BZT powders are distorted rhombohedral and cubic structure, respectively. Moreover, the addition of BZT in BFO-BTO-BZT ceramics affected to the phase change dramatically according to increasing of BZT content compared to calcined BFO-BTO powders. All the samples showed cubic perovskite structure. The room temperature dielectric properties decreased with increasing of BTO content, the highest dielectric constant with low losses observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic. Furthermore, the ceramics displayed maximum dielectric constant temperature (T m) above 360 C. Interestingly, all ceramic compositions exhibited typical ferromagnetic hysteresis loop and the highest remanent magnetization observed in 0.75(0.77BFO-0.23BTO)-0.25BZT ceramic.
Effect of Processing, Dopant and Microwave Sintering on the Dielectric Properties of BiFeO3 Ceramic
BiFeO3 is of much importance for novel applications as sensors as well as actuators due to the coupling between magnetic and electric domains above room temperature and accepted high polarization in single crystal and thin film. Bulk BiFeO3 suffers from high impurity phase, poor sinterability and high dielectric loss and weak magnetism. The need of the hour is to prepare nanosize BiFeO3 powder with least amount of impurity phase that can be sintered to high density. Doping with suitable ion is required to improve the magnetic property of BiFeO3. In present work phase pure BiFeO3 is prepared by hydrothermal technique at 200oC. KOH concentration in solution controls the phase purity, powder morphology and particle size. Particle size was in the range of 15-20µm. Effect of polyvinyl alcohol as an additive to control the particle size was also studied. BiFeO3 and samarium doped BiFeO3 was also prepared by solid state method using nanosized Fe2O3 and Bi2O3. BiFeO3 with lowest impurity co...
High temperature dielectric and magnetic response of Ti and Pr doped BiFeO3 ceramics
Ceramics International, 2013
In the present study, four different compositions of Ti and Pr doped BiFeO 3 samples were synthesized by conventional rapid liquid phase sintering and their structural, dielectric, ferroelectric and magnetic properties were investigated. High temperature dielectric study shows different anomalous response for all compositions. A major peak in dielectric constant versus temperature curve is observed at 640 K for pristine BiFeO 3 which shifts to 545 K for Ti doped (BiFe 0.9 Ti 0.1 O 3) sample. Moreover, multiple peaks are observed for Pr doped (Bi 0.9 Pr 0.1 FeO 3) sample in temperature range of 400-800 K. The room temperature P-E loop study shows that the value of maximum polarization increases from 0.185 to 0.859 mC/cm 2 for Pr doped (Bi 0.9 Pr 0.1 FeO 3) sample and also increases the ability of BiFeO 3 to withstand higher electric field. Room temperature magnetic (M-H) curve shows a slight increment in the value of magnetization from 0.071 to 0.078 emu/gm for pristine BiFeO 3 to Pr and Ti co-doped Bi 0.9 Pr 0.1 Fe 0.9 Ti 0.1 O 3 , respectively.