S V Suryanarayana
Articles written in Bulletin of Materials Science
Volume 17 Issue 4 August 1994 pp 405-409
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 (d
Volume 23 Issue 5 October 2000 pp 431-437
The system SrBi4Ti4−3
Volume 23 Issue 6 December 2000 pp 483-489 Oxide Ceramics
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
Volume 24 Issue 5 October 2001 pp 487-495 Electrical Properties
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.
Volume 24 Issue 5 October 2001 pp 497-504 Electrical Properties
The effect of lanthanum doping is studied on ferroelectric properties of Ba1–𝑥La𝑥TiO3 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, 𝑇c 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 Ba1–𝑥La𝑥TiO3 with 𝑥 = 0.003 were found to be much larger than that of pure barium titanate.
Volume 26 Issue 2 February 2003 pp 247-253 Electrical Properties
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.
Volume 26 Issue 7 December 2003 pp 745-747 Electrical Properties
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.
Volume 28 Issue 5 August 2005 pp 419-422 Composites
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% Ni0.97Co0.03Mn0.01 Fe1.9O4 + 60% BaTi1.02O3.04. The results with varying d.c. and a.c. magnetic fields are presented.
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