Composites of BaTiO₃ and CoFe₂O₄ have been prepared with various compositions by double sintering method. The presence of the two phases has been confirmed by XRD. Variation of dielectric constant with temperature in these samples has been studied. All the samples have shown linear magnetoelectric conversion in the presence of static magnetic field. The magnetoelectric effect (dE/dH) has been studied as a function of intensity of magnetic field. The maximum value of the conversion factor (dH/dH)_max was found to be 0·16 mV/cm/Oe.

The system SrBi₄Ti_4−3xFe_4xO₁₅ belonging to bismuth layer structured ferroelectric (BLSF) materials withx = 0, 0.1 and 0.2 has been prepared through solid-state double sintering method. Increase of iron content in SrBi₄Ti₄O₁₅ resulted in densification of the samples. The normal puckering observed in the sample has been found to decrease and the lattice distortion increased. Dielectric measurements indicate the ferroelectric transition temperature of the samples to be 530°C, 560°C and 606°C. The increase of transition temperature with increasing iron content is correlated with lattice distortion. Conductivity measurements show two slopes and the activation energies have been found to increase with the iron content. Impedance spectroscopy measurements confirm insulating behaviour at lower temperatures. With increase in temperature the samples become conducting and show relaxational effects. The Cole-Cole plots at higher temperatures are found to be semicircles. The relaxation times decrease with the increase of iron content.

X-ray diffraction, a.c. impedance and conductivity (a.c. and d.c.) have been used to characterize DyBi₅Fe₂Ti₃O₁₈. Samples were prepared by solid state double sintering method. A few samples were also subjected to hot isostatic pressing (HIP) at 800°C for 2 h at 100 MPa pressure. The data on XRD, impedance and conductivity of two sets of samples are compared to understand study of effect of HIPing on the properties of DyBi₅Fe₂Ti₃O₁₈

The compound, LaBi₅Fe₂Ti₃O₁₈, is a five-layered material belonging to the family of bismuth layered structure ferroelectromagnetics. D.c. and a.c. conductivity measurements were performed on the samples. Dielectric measurements were also performed on these samples. Combined impedance and modulus plots were used as tools to analyse the sample behaviour as a function of frequency. Cole–Cole plots showed non-Debye relaxation.

The effect of lanthanum doping is studied on ferroelectric properties of Ba_1–𝑥La_𝑥TiO₃ with 𝑥 = 0.0005, 0.001, 0.003 prepared through solid state sintering route. Dielectric and impedance spectroscopic studies have been carried out. The tetragonal distortion of the unit cell decreased and ferroelectric transition temperature, 𝑇_c increased with the increase of lanthanum content.

Combined impedance and admittance spectroscopy was used to analyse impedance data. The electromechanical parameters were calculated from the resonant and anti-resonant frequencies from vector admittance plots. The electromechanical coefficients for Ba_1–𝑥La_𝑥TiO₃ with 𝑥 = 0.003 were found to be much larger than that of pure barium titanate.

The electrical properties of polycrystalline Bi₆Fe₂Ti₃O₁₈ are investigated by impedance spectroscopy in the temperature range 30–550°C. The imaginary part of impedance as a function of frequency shows Debye like relaxation. Impedance data are presented in the Nyquist plot which is used to identify an equivalent circuit and the fundamental circuit parameters are determined at different temperatures. The grain and grain-boundary contributions are estimated. The results of bulk a.c. conductivity as a function of temperature and frequency are presented. The activation energies for the a.c. conductivity are calculated. The polaron hopping frequencies are estimated from the a.c. conductivity data.

Piezoelectric 3–0 composite ceramics are prepared from a mixture of barium titanate and lithium ferrite phase constituents. Dielectric properties of composites are affected by a number of parameters that include electrical properties, size, shape and amount of constituent phases. The frequency dependent measurements can provide additional insight into mechanisms controlling electrical response. Frequency dependence of dielectric constant plots of lithium ferrite/barium titanate composites will be given and the relevance of trends seen in them will be discussed. Connectivity in composites developed is studied.

Magnetoelectric (ME) composites are two-phase composites consisting of piezoelectric and piezomagnetic materials as the participating constituents. These magnetoelectric composites when placed under external magnetic field, show electrical polarization (magnetoelectric output). The ME coupling is mediated by mechanical stress. In the present study, we have synthesized Ni/PZT/Ni and Fe/PZT/Fe layered composites for studying their ME output by dynamic magnetoelectric set up in which both d.c. and a.c. magnetic fields can be varied. The ME output obtained in these composites are higher than those obtained in 40% Ni_0.97Co_0.03Mn_0.01 Fe_1.9O₄ + 60% BaTi_1.02O_3.04. The results with varying d.c. and a.c. magnetic fields are presented.