In this work, we have prepared intergrowth of multiferroic compounds namely Bi4RTi3Fe0.7Co0.3O15-Bi3RTi2Fe0.7Co0.3O12−δ (BRTFCO15-BRTFCO12) (rare earth (R) = Dy, Sm, La) by solid-state reaction method. From the X-ray diffraction Rietveld refinement, the structure of the intergrowths was found to be orthorhombic in which satisfactory fittings establish the existence of three-layered (space group: b 2 c b) and four-layered compounds (space group: A21am). Analysis of magnetic measurements confirmed a larger magnetization for theSm-modified intergrowth compound (BSTFCO15-BSTFCO12) compared to Dy- and La-doped ones. The emergence of higher magnetic properties can be due to distortion in the unit cell when some Bi3+ ions are replaced with the Sm3+, bonding of Fe3+-O-Co3+ as well as a possible mixture of FexCoy-type nanoparticles that are formed generally in the synthesis of intergrowths. The changes in the magnetic state of the Aurivillius intergrowths have been reflected in the magnetoelectric (ME) coupling: higher ME coefficient (~30 mV/Cm-Oe) at lower magnetic fields and is constant up to 3 kOe. The results were corroborated by Raman spectroscopy and variation of temperature with magnetization data. The results revealed that the RE-modified intergrowth route is an effective preparative method for higher-layer Aurivillius multiferroic ceramics.

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In the current study, the tunnel-type titanate nanomaterial (Na2Ti3O7, NaTO) was converted into PdTi3O7 (PdTO) through the ultrasonication-assisted ion-exchange method. The Ag nanoparticles were then deposited on the surface...

Here, we have studied the phase transition and magneto-electric properties of a 70 wt. % Pb(Fe0.5Nb0.5)O3–30 wt. % Co0.6Zn0.4Fe1.7Mn0.3O4 (70 wt. % PFN–30 wt. % CZFMO) multiferroic composite that exhibits a maximum magneto-electric (ME) coefficient of 26.78 mV/cm Oe at room temperature. Raman analysis confirms the formation of composite and development of strain with the shifting of Raman modes. The local symmetry breaking of end members of the composite is observed by the splitting of Raman modes. The first-order derivative of magnetization with temperature (dM/dT vs T) shows anomalies across 140 K due to the PFN phase, whereas the anomaly around 250 K is due to the spin glass transition of the CZFMO phase. The magnetization vs magnetic field (M–H) study at different temperatures reveals the existence of superparamagnetic behavior above 300 K. The temperature-dependent dielectric behavior of the composite shows an anomaly around ferroelectric phase transition (Tm) for the PFN phase along with the broad relaxation peak arising due to the CZFMO phase. The linear behavior of magnetocapacitance (MD%) with the square of magnetization (M2) suggests the existence of biquadratic ME coupling. The ME study on the composite suggests the existence of both direct and converse ME effects.

Novel samarium modified intergrowth ferroelectric ceramics, namely Bi 4 Ti 3 O 12 -SrBi 4 Ti 4 O 15 , were synthesized by conventional solid state reaction method and sintered at 1100°C for 5 h. X-ray diffraction studies revealed the formation of a single phase with the signature of intergrowth oxide and plate like morphology was observed by scanning electron microscopic analyses. The orthorhombicity, the grain size and transition temperature were found to decrease with the increase of Sm content. The dielectric and modulus measurements were performed at different temperatures and frequency ranges. The transition temperature was found to be around 500°C. The variations of imaginary part of modulus and dielectric constant with the temperature showed diffuse phase transition. The results are corroborated to the defect based mechanism and Curie deviation factor was evaluated by using the modified Curie-Weiss law. Polarization-electric filed curves displayed a typical narrow hysteresis loop at room temperature by applying an electric field of 70 kV/cm. However, above room temperature the hysteresis loop area was found to be increased. The overall results revealed that the complex dipoles and oxygen vacancies are playing a dominant role in the dielectric and electrical properties, and therefore the adopted intergrowth processing was found to be an effective approach to obtain potentially good ferroelectric materials.

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Multiferroic composites consisting of a single-phase multiferroic [0.6(PbZr0.53Ti0.47O3)-0.4(PbFe0.5Ta0.5)O3] as a matrix and a magnetostrictive phase (Co0.6Zn0.4Fe1.7Mn0.3O4) dispersed in the matrix are fabricated via hybrid synthesis technique. The structure and surface morphology studies using x-ray diffraction and field emission scanning electron microscopy techniques indicate the formation of 3-0 type particulate composites. Coexistence of soft-magnetic behavior and ferroelectric characteristics are confirmed for composites from magnetization vs magnetic field (M–H) and polarization vs electric field (P–E) measurements, respectively. Magneto-dielectric (MD) measurement shows significant changes in the dielectric properties with the application of a magnetic field, indicating the existence of strong MD behavior. The biquadratic nature of magneto-electric (ME) coupling is described by the Landau free energy equation arising from the strain transfer at the interfaces between the constituent phases. The direct magneto-electric voltage coefficient measurement also confirms very strong coupling between ferroelectricity and magnetism and supports the strain-mediated magneto-electric effect in composites. The Φ = 0.3 composite exhibits the maximum ME coefficient of 20.72 mV/cm Oe with MS = 24.62 emu/g, HC = 59.66 Oe, and piezoelectric coefficient value d33 = 19 pC/N. The strong magneto-electric effect along with low dielectric loss at room temperature in these composites suggests their suitability for multifunctional magneto-electric device applications such as magnetic sensors, etc.

Development of lead-free BaTiO3/NiFe2O4/BaTiO3 (BTO/NFO/BTO) trilayer structure thin films is significant for the realization of eco-friendly and implantable microelectromechanical systems (MEMS)-based devices. In the present work, we report BTO/NFO/BTO trilayer structure as a representative ferroelectric/ferromagnetic/ferroelectric (FE/FM/FE) system deposited on Pt(111)/TiO2/SiO2/Si using Pulsed Laser Deposition (PLD) technique. We report the ferroelectric, magnetic, and ME properties of BTO/NFO/BTO trilayer nanoscale heterostructure having dimensions 140/80/140 nm, at room temperature. High room temperature dielectric constant ~2145 at 100 Hz with low dielectric loss ~0.05 at 1 MHz is observed. Further, the deposited (BTO/NFO/BTO) tri-layered thin films showed magnetoelectric, multiferroic behavior with remanent polarization of 8.63 μCcm−2 at about 0.25 MV/cm and a reasonably high saturation magnetization of ~16 emu/cm3 at ~10 kOe is witnessed at room temperature. Tri-layered films have shown interesting magnetoelectric (ME) coupling coefficient (αE) ~54.5 mV/cm Oe at room temperature.