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Polycrystalline [(0.5) Bi0.5Na0.5TiO3-(0.5) LaFeO3] multiferroic composite is prepared by using the solid-state reaction method. The crystal structure of both phases is characterized by using the X-ray diffraction method (XRD) and confirms the presence of rhombohedral (i.e., bismuth sodium titanate) and orthorhombic (i.e., lanthanum ferrite) phases in the composite. The microstructure of the composite is analyzed using field emission scanning electron microscopy (FESEM). The crystal structure is further studied with Raman spectroscopy. The present composite exhibits ferroelectric and ferrimagnetic-like properties, revealing its multiferroic behavior. Furthermore, the impedance analysis of the composite shows the negative temperature coefficient of resistance behavior. The present study describes the structural and physical properties of the possible lead-free multiferroic composite. [ABSTRACT FROM AUTHOR]

A multiferroic material with a wide range of uses is bismuth ferrite, which shows outstanding potential. Ca and Ti co-doped BFO samples have been synthesized by the modified sol–gel method. The crystal structures of the samples have been confirmed by x-ray diffraction. The microscopic dielectric relaxations and conduction processes in these materials have been analyzed using complex impedance, complex electric modulus, and frequency-dependent ac conductivity analyses. The modified Debye's function has been used to study the dispersion behavior of the dielectric constant. The brick-layer model has been used to describe the dielectric characteristics of each sample. Furthermore, to study the conduction mechanism, ac conductivity data have been analyzed using Jonscher's power law and the Arrhenius equation. The Arrhenius technique was used to calculate the relaxation time as well as the activation energies using the imaginary part of the electrical impedance and the modulus. The presence of non-Debye-type relaxation processes, which include localized and long-range relaxation processes, is supported by the electric modulus spectroscopy. [ABSTRACT FROM AUTHOR]

The copper ferrite fiber has been synthesized using the electrospinning technique by optimizing the electric voltage and viscosity of the polymer solution. Physical properties of copper ferrite fiber have been tuned with annealing at different temperatures (550, 750, and 950 °C for 2 h). The crystal structure has been confirmed by X-ray-diffraction pattern analysis and studied by using Rietveld refinement technique. The morphology of fibers was explored with the help of field emission scanning electron microscopy. The fibers annealed at 550 °C crystallize to cubic structure, and the tetragonal phase has been observed for 750 °C, and 950 °C annealed fibers. Sample annealed at 750 °C shows the highest magnetocrystalline anisotropy constant at 300 K (3 × 105 erg/cc). The SAR (Specific absorption rate) and ILP (intrinsic loss power parameter) of the 750 °C annealed fibers are 265 ± 5 W/g and 3.412 nHm2/Kg, respectively. The SAR value calculated by using non-adiabatic approach is 335 W/g. [ABSTRACT FROM AUTHOR]

The evolution of microstructure (grain size) with the sintering temperature and its effect on the electrical properties has been investigated for ((Bi0.5Na0.5)0.94Ba0.06)0.70Sr0.30TiO3 [BNBSTO] electroceramic. The X-ray diffraction patterns and the Rietveld refinements reveal the formation of the single phase with perovskite structure. The relative dielectric constant increases with the sintering temperature up to 1175 °C. Temperature-dependent relative permittivity shows the dispersive nature with the diffuse electrical phase transitions. The diffusivity of the electrical properties of the electroceramics has been estimated using the Curie–Weiss law. It is observed that the electrical diffuseness decreases with the increase of the grain size. The Nyquist plots reveal the role of grains and grain boundaries on the electrical conductivity of the electroceramic. Also, the grain size affects the ferroelectric properties which directly influences the energy storage density. [ABSTRACT FROM AUTHOR]

In this study, the crystal structure and magnetic properties of two sets of multiferroic nanocomposites of Bi0.85La0.15FeO3 (BLFO) and BaTiO3 (BTO) were reported. The samples were prepared by adopting the conventional solid-state reaction and ball mill technique. The X-ray diffraction pattern and Raman spectra analysis reveal the impurity-free crystal structure, and both the phases (i.e., BLFO and BTO) are present in parallel in the nanocomposites. Scanning electron microscopy was used to study the surface morphology. The saturation magnetizations of the ball-milled nanocomposite are found to be significantly higher compared to that of the solid-state composites. The Vegard law was used to compare the observed saturation magnetization with the oretical values. The pinched hysteresis loop was observed in both sets of composites, which was explained by exchange type magnetic interaction between BLFO and BTO. The squareness ratio (R) tells the presence of intergrain magnetostatic interaction in the composites. The hysteresis loop width (ΔH) versus magnetization (M) plots for all the composites reveals the hysteresis loop anomalies. [ABSTRACT FROM AUTHOR]

The high temperature electrical phase transitions of (1 − x) Bi0.5Na0.5TiO3–(x) Bi0.5K0.5TiO3 (x = 0.10, 0.15, 0.20, 0.25, 0.30 and 0.35) relaxor ferroelectrics have been investigated by employing the dielectric spectroscopy technique. The Rietveld refinement of the XRD patterns reveals the increase of the lattice distortion (c/a) from 1.001 to 1.006 in the tetragonal crystal symmetry (P4mm) with the increase of the BKT (x = 0.10, 0.15, 0.20, 0.25, 0.30 and 0.35) mole fraction. The different bonds vibration (Bi3+/Na+/K+–O and Ti4+–O) related to phonon modes have been studied by analyzing the Raman spectra. The relaxor antiferroelectric ordering temperature (Td: depolarization temperature) of Bi0.5Na0.5TiO3 (BNT) reduce from ~ 200 to ~ 91 °C with the increase of the BKT mole fraction. This observation is well correlated to the formation of polar nanoregions (PNRs) due to the compositional fluctuation in the local crystal structure. Also, Td varies with the frequency of the applied electric. It suggests the presence of the PNRs and, subsequently exhibits the relaxor ferroelectric behavior. The activation energy to activate the PNRs reduces from 2.573 to 2.383 meV with the increase of the BKT mole fraction in the solid solutions. Reduction in remanent electrical polarization and the electrical coercive field in temperature dependent ferroelectric hysteresis loops suggest the relaxor antiferroelectric behavior of the solid solutions (x ≥ 0.15) near the depolarization temperature. [ABSTRACT FROM AUTHOR]