BTO Fe Pt RSC Advances page 596

RSC Advances, 2012

Nanohybrid structures of FePt and BaTiO 3 with bifunctional properties were synthesized by a two step synthesis procedure including solid state and solvothermal methods. Two different compositions of FePt and BaTiO 3 nanoparticle samples were synthesized. The hybrid composite, having the lower FePt concentration, exhibited bifunctionality including superparamagnetism with a blocking temperature near room temperature and ferroelectricity at ambient conditions. Magnetocapacitive measurements of this bifunctional FePt-BiTiO 3 sample showed behaviour typical of weak magnetoelectric coupling. This synthetic approach provides a general method for preparing advanced multifunctional and technologically important ceramic-alloy hybrids.

Journal of Applied Physics, 2023

There is a growing interest in BiFeO 3-based alloys because of the possibility it offers for developing high-temperature high-performance piezoelectric materials and for their interesting multiferroic properties. Often such ceramics are synthesized with additives either to reduce/suppress leakage current that the system inherits from the parent compound BiFeO 3 or to promote sintering via formation of the liquid phase. We demonstrate here the propensity for stabilizing ferromagnetism in the ferroelectric solid solution BiFeO 3-PbTiO 3 (BF-PT) when synthesized with additive MnO 2. Detailed investigation revealed that the ferromagnetic property of the ceramic is extrinsic and caused by the additive enabled precipitation of trace amount of the ferrimagnetic Pb-hexaferrite phase, not easily detected in conventional x-ray diffraction measurements. We also show that the ferromagnetic property is induced in Co-modified BF-PT. However, in this case, the additive stabilizes the CoFe 2 O 4 spinel ferrite phase. While our findings offer a strategy to develop particulate magnetoelectric multiferroic composites using additive assisted precipitation of the ferrimagnetic phase(s) in BiFeO 3-based ferroelectric alloys, it also helps in better understanding of the electromechanical response in BFO-based alloys.

Journal of Applied Physics

There is a growing interest in BiFeO3-based alloys because of the possibility it offers for developing high-temperature high-performance piezoelectric materials and for their interesting multiferroic properties. Often such ceramics are synthesized with additives either to reduce/suppress leakage current that the system inherits from the parent compound BiFeO3 or to promote sintering via formation of the liquid phase. We demonstrate here the propensity for stabilizing ferromagnetism in the ferroelectric solid solution BiFeO3–PbTiO3 (BF–PT) when synthesized with additive MnO2. Detailed investigation revealed that the ferromagnetic property of the ceramic is extrinsic and caused by the additive enabled precipitation of trace amount of the ferrimagnetic Pb-hexaferrite phase, not easily detected in conventional x-ray diffraction measurements. We also show that the ferromagnetic property is induced in Co-modified BF–PT. However, in this case, the additive stabilizes the CoFe2O4 spinel fer...

Bulletin of Materials Science, 2014

Composites comprising of nanoparticles of Ni 0⋅5 Zn 0⋅5 Fe 2 O 4 (NZF) and BaTiO 3 (BT), respectively were synthesized by a chemical method. The particles had diameters in the range of 15-31 nm. NZF was prepared by a coprecipitation technique. This was soaked in a sol containing BT. Compositions synthesized were xNZF-(1x) BT, where x = 0⋅7, 0⋅5 and 0⋅3, respectively. The composites showed ferromagnetic hysteresis loops due to NZF phase. The analysis of coercivity variation as a function of temperature gave blocking temperatures in the range of 306-384 K depending on the diameter of the ferrite nanoparticles. This implied that superparamagnetic interactions are above these temperatures. The nanocomposites also exhibited ferroelectric behaviour arising due to the presence of BT. The remanent polarization of the samples was small. This was adduced to the nanosize of BT. The specimens showed magneto-dielectric (MD) effect in the magnetic field range 0-0⋅7 Tesla. The MD parameter measured at the maximum magnetic field was around 2%. This was one order of magnitude higher than that reported so far in similar composite systems. This was explained on the basis of a two-phase inhomogeneous medium model with an interface between them, the phases possessing drastically different electrical conductivities.

Phase Transitions, 2013

BaTiO 3 -ferrite multiphase composites were prepared starting from di-phase mixtures of -Fe 2 O 3 and BaTiO 3 powders. During the sintering step, the formation of small amounts of secondary phases with multifunctional character as BaFe 12 O 19 or Ba 12 Ti 28 Fe 15 O 84 was promoted. The resulting multiphase ceramic compounds show interesting dielectric, magnetic and small magnetocapacitance effect at low temperature. The coexistence of different magnetic phases with contrasting coercivities (hard/soft) was detected by the presence of 'waspwaisted' M(H) hysteresis loops and first-order reversal curve analysis. The present approach demonstrates that active materials can be realised by controlling in situ reactions at the interfaces in ferroelectric-magnetic oxide composites.

Multiferroic BiFeO3 and Cr-doped (0.90)BiFe1−x CrxO3–(0.10)BaTiO3 (x = 0.00, 0.03, and 0.05) nanocomposites were prepared by sol–gel method. Optimum calcination and sintering strategies for obtaining pure perovskite phase have been determined. X-ray diffraction and transmission electron microscope (TEM) were used for the structural and particle size analysis, whereas LCR and SQUID magnetometer was used for dielectric and magnetic measurements. TEM measurements show that the average particle sizes of all the samples were ∼19 nm. The dielectric constant was found to be increased twofold in low frequency region with the Cr-doping for x = 0.05 in (0.90)BiFe1−xCrxO3– (0.10)BaTiO3. The hysteresis curve (M–H) exhibits ferromagnetic nature for all the samples (x = 0.0, 0.03, and 0.05) and the spontaneous magnetization at room temperature was found to be 0.63 emu/gm in pure BiFeO3, which increased to 0.99 emu/gm for x = 0.05. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves show large discrepancy suggesting spin glass behavior.

Materials Chemistry and Physics, 2010

Solid solutions of xBiFeO 3 -yPrFeO 3 -zPbTiO 3 (xϩyϩzϭ1) and (1Ϫw)BiFeO 3 -wPbTiO 3 have been explored for finding ferroelectromagnetic bulk material, in which ferroelectricity and ferromagnetism coexist simultaneously. The coexistence has been observed only in some ternary composition samples, that is, 0.2BiFeO 3 -0.2PrFeO 3 -0.6PbTiO 3 and 0.4BiFeO 3 -0.2PrFeO 3 -0.4PbTiO 3 . In the ternary solid solutions, spontaneous magnetic moments disappear with the decrease of PrFeO 3 content to yϽ0.2 independently of BiFeO 3 content. When PrFeO 3 content remains constant at yϭ0.2, the ternary solid solutions become paraelectric with the decrease of PbTiO 3 content to zр0.2. The ferroelectromagnetic solid solutions have the noncentrosymmetric and doubled perovskite unit cell with a space group I4cm (aϭbϷ5.4 Å, c Ϸ7.9 Å͒. Addition of Ta 2 O 5 dopant substantially changes the polarization-electric-field and magnetization-magnetic field curves of the 0.2BiFeO 3 -0.2PrFeO 3 -0.6PbTiO 3 . The binary solid solutions of (1Ϫw)BiFeO 3 -wPbTiO 3 do not exhibit spontaneous magnetic moments down to 10 K over the entire composition range.

Vacuum, 2019

Bulk BaTiO 3 ceramics are prepared by solid state reaction route by varying Ba/Ti ratio from 0.990 to 1.005 in steps of 0.005 to study the influence of Ba/Ti ratio on the origin of ferromagnetism in the otherwise diamagnetic material. Structural investigation confirmed the coexistence of two-phase structural model, tetragonal (P4mm) + orthorhombic (Amm2) using Rietveld refinement program. For the first time, structural defect of Ti vacancies are quantified using refinement while the Ba and O are fully occupied. Room temperature magnetic M-H measurements have indicated that the diamagnetic-like and ferromagnetic-like loops in Ti-rich and Ti-deficient BaTiO 3 system respectively. The ferromagnetic-like behavior (Ti-deficient) is originated from the intrinsic defect that is Ti vacancy which plays a decisive role in the magnetic property of otherwise non-magnetic BaTiO 3 ceramics. Magnetodielectric constant is negligible in Ti-rich samples while high value of magnetodielectric constant is obtained as-0.88% at 8kOe in Ba/Ti = 1.005 sample.

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.

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.