Articles written in Bulletin of Materials Science
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 29 Issue 1 February 2006 pp 35-41 Ceramics and Glasses
Polycrystalline ceramic samples of sodium bismuth titanate with simultaneous doping at A and B sites have been studied for the influence of these dopants on the electrical conduction mechanism. A.C. conductivity measurements were done on the prepared sample in a wide range of frequency and temperature. These studies revealed that the conduction in the sample arises due to hopping of bound charges. Four-term power law is used to characterize the frequency dependence of a.c. conductivity. From the temperature dependence of the exponents, the a.c. conduction in the samples is explained.
Volume 29 Issue 4 August 2006 pp 347-355 Ceramics and Glasses
Electrical conduction studies on Ba(Nd0.2Ti0.6Nb0.2)O3 ceramic samples prepared through conventional and microwave sintering route are presented in this paper. D.C. and a.c. conductivities of these samples as a function of temperature from 300–900 K have been studied. Two types of conduction processes are evident from the frequency dependant conductivity plots, i.e. low-frequency conduction due to short-range hopping and high-frequency conduction due to the localized relaxation (reorientational) hopping mechanism. Grain and grain boundary contributions to the conductivity in these samples are obtained from impedance/admittance measurements via equivalent circuit modelling.
Volume 31 Issue 2 April 2008 pp 133-138 Electrical Properties
New NASICON type materials of composition, Li3–2𝑥Al2–𝑥Sb𝑥(PO4)3 (𝑥 = 0.6 to 1.4), have been prepared and characterized by powder XRD and IR. D.C. conductivities were measured in the temperature range 300–573 K by a two-probe method. Impedance studies were carried out in the frequency region 102–106 Hz as a function of temperature (300–573 K). An Arrhenius behaviour is observed for all compositions by d.c. conductivity and the Cole–Cole plots obtained from impedance data do not show any spikes on the lower frequency side indicating negligible electrode effects. A maximum conductivity of 4.5 × 10-6 S cm-1 at 573 K was obtained for 𝑥 = 0.8 of the Li3–2𝑥Al2–𝑥Sb𝑥(PO4)3 system.
Volume 35 Issue 4 August 2012 pp 579-584
Composite piezoelectric ceramics are important materials for transducer applications in medical diagnostic devices and MEMS devices. In micrometer scale the material properties of piezopolymers or piezoceramics do not coincide with that of bulk materials. The present work is aimed at simulating the material properties of piezoceramics and piezo-polymer composite thin films in the micrometer scale and then to determine the piezo-composite material properties. Piezoceramics have very high electromechanical coupling coefficient (𝑘). But they have very high acoustic impedance and they are very brittle especially when thin films are fabricated. Piezopolymer like PVDF has low acoustic impedance and can be fabricated into thin films but it has very low 𝑘 value and high dielectric losses. The combination of piezoceramics and piezopolymers form the piezocomposites, which have suitable material properties for transducer applications. The composites can have different connectivities. For 2–2 composite, we can select two layers or a stack of PZT and PVDF layers. It is intended to determine the material properties both analytically and by simulation using computer simulation ANSYS software which implements finite element method (FEM). Although the simulation process presents approximate results, it can be verified from the large available experimental data from the literature with the simulated data.
Volume 42 | Issue 5