Enhanced Magnetic and Ferroelectric Properties and Current-Voltage Hysteresis by Addition of La and Ti to BiFeO 3 on 0.7%Nb-SrTiO 3 (original) (raw)
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Social Science Research Network, 2022
Textured multiferroic Bi 5 Ti 3 FeO 15-CoFe 2 O 4 (BTFO-CFO) ceramics were prepared via microwave hydrothermal synthesis followed by plasma activated sintering. BTFO-CFO ceramics with CFO nanoparticles distributed between the BTFO layers exhibit a high degree of texture (f =0.8) along the c-axis crystallographic orientation, which was confirmed by a combination of XRD, SEM and TEM. BTFO-CFO composite ceramics exhibit desirable magnetic and ferroelectric properties due to the ferromagnetic phase (CFO) and textured ferroelectric phase (BTFO). The current work provides a feasible method to fabricate textured multiferroic composite ceramics.
Research Square (Research Square), 2021
0.9Bi 1 − x Nd x FeO 3-0.1PbTiO 3 solid solution where x = 0.05, 0.10, 0.15 and 0.20 were success fully synthesized by the standard solid-state reaction method. The effect of Nd 3+ ion substitution on structural, micro structural, ferroelectric, magnetic, dielectric and magneto-electric properties of 0.9BiFeO 3-0.1PbTiO 3 have been investigated. The XRD analysis for the samples under study revealed distorted rhombohedral structure with R3C space group. 0.9Bi 1 − x Nd x FeO 3-0.1PbTiO 3 where x = 0.05, 0.10, 0.15 and 0.20 i.e. (BNFPT)x compounds crystallised as single-phase materials with the same structure as the parent BiFeO3 compound.. The SEM study revealed the uniform grain scattering for all prepared samples. Raman spectroscopy showed disappearance of some Raman modes indicated a structural phase transition with substitution of Nd dopants at Bi site and also con rmed the distorted rhombohedral perovskite structure of (BNFPT) x compounds with R3c symmetry. Dielectric measurements showed magnetoelectric coupling around Neel temperature in all the samples and also improved dielectric properties with addition of dopants in BiFeO 3 (BFO) compound. All the prepared samples exhibit weak ferro-magnetic character at room temperature. However, the variation in linear behavior and enhancement in magnetization is found at 5 K which shows gradual increase in remnant magnetization from 0.00785 emu/g to 0.37513 emu/g with increase in Nd doping for all (BNFPT) x samples. Nd doping reduces leakage current by three orders of magnitude, from 10 − 4 to 10 − 7. Ferroelectric study revealed the pinning effect in hysteresis loops with low remnant polarization.
Ferroelectromagnetic characteristic of Na-doped 0.75BiFeO 3 -0.25BaTiO 3 multiferroic ceramics
BiFeO 3-based materials are expected to have both ferroelectricity and ferromagnetism simultaneously. In this study, effects of Nadoping (0.5, 1.0, 3.0, and 5.0 mol%) on ferromagnetic and ferroelectric properties of 0.75BiFeO 3-0.25BaTiO 3 ceramics which have been fabricated by the solid state reaction technique are studied. The effects of Na-doped 0.75BiFeO 3-0.25BaTiO 3 ceramics on the crystal structure, and magnetic and electrical properties were investigated and discussed. Rhombohedrally distorted 0.75BiFeO 3-0.25BaTiO 3 showed weak ferromagnetic and ferroelectric properties. In addition, ferroelectric and ferromagnetic properties of 0.75BiFeO 3-0.25BaTiO 3 have been controlled by Na doping, and the maximum values of magnetization and polarization were observed at 5.0 mol%.
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.
Ferroelectric and Ferromagnetic Properties of K-doped 0.7BiFeO 3 -0.3BaTiO 3 Multiferroic Ceramics
Lead-free and multiferroic 0.7BiFeO 3-0.3BaTiO 3 ceramics doped with K (0.5, 1.0, 3.0 and 5.0 mol%) have been successfully prepared by a solid state mechanical milling technique. The single phase perovskite was found at calcination temperature of 900 • C for 6 h. The effects of K doping on the crystal structure, microstructure, magnetic and electrical properties of lead-free 0.7BiFeO 3-0.3BaTiO 3 ceramics were investigated and discussed. The fracture micrographs of specimens elucidate the grain growth behavior with increasing K content up to 3.0 mol%. The weak ferromagnetic and ferroelectric properties were observed in rhombohedrally-distorted 0.7BiFeO 3-0.3BaTiO 3 perovskite ceramic. However, the addition of K into 0.7BiFeO 3-0.3BaTiO 3 has been found to improve the ferroelectric and ferromagnetic properties , with the optimized properties obtained at 3.0 mol% content of K.
Materials Research Bulletin, 2018
6% Sm-Ti co-doping induces phase transition SEM analysis of Bulk materials Highlights Bulk samples Bi1-xSmxFe1-yTiyO3 were synthesized by solid-state reaction and their corresponding nanoparticles by ultrasonication method. Structural, ferroelectric and magnetic properties were compared between nanoparticles and their corresponding bulk counterparts. Structural phase transition of Bi0.94Sm0.06Fe0.94Ti0.06O3 with negligible impurity phases. Significant reduction of leakage current density in the synthesized nanoparticles. Enhanced ferromagnetic behavior 4 Enhanced ferromagnetic behavior in 6% Sm-Ti co-doped BiFeO3 nanoparticles compared to its corresponding bulk counterparts.
Microstructure and properties of Co-, Ni-, Zn-, Nb- and W-modified multiferroic BiFeO3 ceramics
Journal of the European Ceramic Society, 2010
BiFeO 3 polycrystalline ceramics were prepared by the mixed oxide route and a chemical route, using additions of Co, ZnO, NiO, Nb 2 O 5 and WO 3. The powders were calcined at 700 • C and then pressed and sintered at 800-880 • C for 4 h. High density products up to 96% theoretical were obtained by the use of CoO, ZnO or NiO additions. X-ray diffraction, SEM and TEM confirmed the formation of the primary BiFeO 3 and a spinel secondary phase (CoFe 2 O 4 , ZnFe 2 O 4 or NiFe 2 O 4 depending on additive). Minor parasitic phases Bi 2 Fe 4 O 9 and Bi 25 FeO 39 reduced in the presence of CoO, ZnO or NiO. Additions of Nb 2 O 5 and WO 3 did not give rise to any grain boundary phases but dissolved in BiFeO 3 lattice. HRTEM revealed the presence of domain structures with stripe configurations having widths of typically 200 nm. In samples prepared with additives the activation energy for conduction was in the range 0.78-0.95 eV compared to 0.72 eV in the undoped specimens. In co-doped specimens (Co/Nb or Co/W) the room temperature relative permittivity was ∼110 and the high frequency dielectric loss peaks were suppressed. Undoped ceramics were antiferromagnetic but samples prepared with Co or Ni additions were ferromagnetic; for 1% CoO addition the remanent magnetization (M R) values were 1.08 and 0.35 emu/g at temperatures of 5 and 300 K, respectively.
Multiferroic materials of BiFeO 3-BaTiO 3 solid solution have been fabricated in order to improve ferromagnetic and ferroelectric properties. The effects of La (1 mol%) and K (varied from 0.5-5 mol%) doped 0.75BiFeO 3-0.25BaTiO 3 on phase formation, ferromagnetic and ferroelectric properties have been investigated and discussed. The rhombohedral perovskite phase of specimens was characterized by XRD technique. Fracture morphology reveals the grain growth characteristics with increasing K content. (La, K)-doped 0.75BiFeO 3-0.25BaTiO 3 with La¼1 mol% and K¼3 mol% exhibits the highest remnant polarization and remnant magnetization.
Preparation and properties of (1−x)BiFeO3–xBaTiO3 multiferroic ceramics
Solid solutions of (1−x)BiFeO3–xBaTiO3 (0≤x≤0.30) have been prepared by a two-step solid state reaction. By comparison with other reported methods, a higher electrical homogeneity of the ceramic bodies resulted in better dielectric properties, with a single-component impedance plot, small losses and permittivities below 240. The maximum magnetization is observed for x = 0.05, which might represent the proper range of compositions for multiferroism at room temperature. In order to better understand the composition-dependent magnetic properties in correlation with the expected Fe2+/Fe3+ ratio fluctuations in the solid solutions, a detailed X-ray Photoelectron Spectroscopy (XPS) analyses were performed on the surfaces and on the fractured sintered bodies.
Structural, dielectric and multiferroic properties of Er and La substituted BiFeO3 ceramics
Bulletin of Materials science, 2010
Erbium (Er) and lanthanum (La) substituted BiFeO3 (BFO) ceramics have been prepared through conventional solid solution route. X-ray diffraction data indicated a gradual phase transition from rhombohedral to monoclinic structure in Bi0⋅9–x La0⋅1ErxFeO3 (x = 0⋅05, 0⋅07 and 0⋅1) (BLEFOx = 0⋅05, 0⋅07,0⋅1) ceramics. Differential thermal analysis (DTA) measurements of BFO samples showed a ferroelectric transition at 835°C, whereas it is shifted to 792°C for BLEFOx = 0⋅1. The Raman spectra of BLEFOx = 0⋅05,0⋅07,0⋅1 samples showed the shift of Raman modes to higher wavenumbers and suppression of A1 modes indicating decrease in ferroelectricity. The Raman spectra also indicated the structural transformation due to Er and La substitution in BFO. On subsequent erbium doping, the intrinsic dielectric constant is found to decrease from 68 (for pure BFO) to 52 for BLEFOx = 0⋅05 to 43 for BLEFOx = 0⋅07 but increased to 89 for BLEFOx = 0⋅1 when compared to pure BFO. The increase in Er content resulted in the increase in spontaneous magnetization (0⋅1178 emu/g at 8T for BLEFOx = 0⋅1) due to collapse of spin cycloid structure. Ferroelectric remnant polarization of BLEFOx = 0⋅05 and BLEFOx = 0⋅07 decreases when compared to pure BFO while small remnant polarization (close to paraelectric behaviour) is evident for BLEFOx = 0⋅1