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In the present study, we have prepared the [Ba(Nd0.075Ti0.85Nb0.075)O3]0.30–[(Na0.5Bi0.5)TiO3]0.70 ceramic through solid-state double sintering route. New equations which were proposed by us earlier were used to describe and model the electromechanical, AC and DC resistivity data. The activation energy for resonance and anti-resonance at 300 K is 30.28 and 30.11 meV; whereas the value is 38.32 and 38.91 meV at 448 K. The higher activation energy for AC conduction when compared to DC conduction is attributed to the fast vibration of charged polar and conducting species in response to the applied frequency, which requires more temperature. [ABSTRACT FROM AUTHOR]

Ba(NdxTi1-2xNbx)O3 (with x = 0.025, 0.05, 0.1, and 0.2) and Na0.5Bi0.5(NdyTi(1-2y)Nby)O3 (y = 0.0125, 0.025, and 0.05) ceramics were prepared through solid state sintering route. In the present study modulus resonance studies at high temperatures were carried out on the above ceramics. Higher piezoelectric performance in terms of parameters like thickness mode of electromechanical coupling factor and piezoelectric charge constant were observed for the ceramic compositions operating at higher temperature regime (798–873 K). In the case of ceramic composition with y = 0.0125, 0.025, and 0.05, the piezoelectric charge constant operating at 798K are 26.16 nm.V−1, 17.74 nm.V−1, and 24.33 nm.V−1, respectively. [ABSTRACT FROM AUTHOR]

Modified Lorentz and Gauss equation is proposed to describe the temperature dependence of dielectric constant for bismuth layered structure ferroelectric materials i.e. Sr1-2xNaxNdxBi4Ti4O15. The validity of the proposed equation was checked from the regression value obtained. The activation energy for orientation of dipoles, static dielectric constant and infinite dielectric constant obtained from the non linear curve fitting to experimental data by using modified Lorentz and Gauss equation have reasonable values. Modified Lorentz equation is found to be the best fit to the experimental dielectric data. The above modified equations may also be used to describe the dielectric behaviour of other normal ferroelectric materials which show sharp transitions. [ABSTRACT FROM AUTHOR]

The bismuth layer structured ferroelectric (BLSF) ceramics consisting of four-layers (BaLa0.75Bi3.25Ti4O15) and five-layers (Ba2La0.75Bi3.25Ti5O18) were prepared by the conventional solid-state reaction method. Summerfield ac-conductivity scaling analysis was used to evaluate the electrical behavior and the ac-conductivity isotherm curves. The relaxation results were corroborated with the Raman Peak positions and full width at half maximum was obtained by using Lorentzian peak fit method. Finally, the results were compared with the two-layered relaxor-compound (Bi2.45La0.55TiNbO9) and technologically standard three-layered compounds (La0.75Bi3.25Ti3O12; BLT). The dielectric relaxation of Bi2.45La0.55TiNbO9was verified using modified Curie-Weiss law and Vögel-Fulcher relationship. An attempt is made to realize the typical collective nature of the ionic conductivity of the samples. [ABSTRACT FROM AUTHOR]

Nano particulate Barium Bismuth Titanate (BaBixTi1-xO3-δ) materials with (x = 0.25, 0.075. 0.125 and 0.175) were prepared through sol-gel chemical route (Pichini method) and the XRD patterns were indexed on the basis of tetragonal-BaTiO3 phase. The electrical impedance measurements were carried out on the samples by using Auto Lab PGSTAT30 impedance analyzer in the frequency region 100 Hz-1 MHz from RT to 500°C. Impedance spectroscopic and complex explicit plots show the presence of both bulk and grain boundary effects, and impedance spectroscopy is shown to be an efficient method capable of detecting the conductivity species and estimating the electrical conductivity as well as activation energy value. Finally, the results are interpreted in terms of the defect dynamics and conduction mechanisms taking place in the samples. [ABSTRACT FROM AUTHOR]

Effect of doping in Na0:5Bi0:5TiO3 (NBT) with Ce3+ and Sm3+ at the A-site on dielectric behaviour, impedance and conductivity is being reported. Na0:5Bi0:5-xAxTiO3 samples (A being Ce and Sm) are studied with varying values of x. For Na0:5Bi0:5-xCexTiO3 samples x is 0.001, 0.005 and 0.007 and for Na0:5Bi0:5-xSmxTiO3 samples x is 0.05, 0.1 and 0.15. Dielectric constant and loss are studied in the frequency range 10 kHz to 1 MHz and in the temperature range 30-650°C. Impedance and electric modulus studies are undertaken. The relaxations observed in the samples are non-Debye and activation energies for relaxation and conduction are evaluated. [ABSTRACT FROM AUTHOR]

The Aurivillius-type compounds with generic formula SrxBi4-xNbxTi3-xO12 (with x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been synthesized to investigate the effect of Sr and Nb substitution on the bismuth titanate, by a conventional solid state technique. The phase formation of the compound was confirmed through XRD. The dielectric measurements were made at different constant frequencies of 10 kHz, 50 kHz, 100 kHz, 500 kHz and 1 MHz over a wide temperature range. The samples showed a transition from normal ferroelectric behavior to relaxor dielectric behavior with an increasing value of "x". [ABSTRACT FROM AUTHOR]

The effect of lanthanum doping on the electromechanical properties of lanthanum-doped sodium bismuth titanate was studied. The ferroelectric system under investigation was Na1/2(LaxBi1-x)1/2TiO3 ceramics, with x=0, 0.1, 0.15 and 0.2. Admittance measurements were carried out in the frequency range of 100 Hz to 13 MHz and in the temperature range from room temperature to 550°C. Combined impedance and admittance spectroscopy was used to analyze admittance data. The electromechanical parameters were calculated from the resonant and anti-resonant frequencies obtained from vector admittance plots. The electromechanical coefficients for pure sodium bismuth titanate ceramic samples were found to be much larger than the reported values. Also, it was observed that lanthanum-doping decreased the values of electromechanical coupling coefficients. [ABSTRACT FROM AUTHOR]

Bismuth in SrBi 4 Ti 4 O 15 is partially replaced with La 3 + to synthesize SrBi (4 - X ) La X Ti 4 O 15 , with x = 0.25,0.5,0.75. The samples have been prepared by sol-gel method using ethylene glycol gel and aqueous solution. This sol-gel process offers some advantages, such as homogeneity and stoichiometry control. The structural characterization of the samples is done using powder X-ray diffraction measurements. The samples are electrically characterized by using dielectric and impedance spectroscopy measurements in the frequency range of 500 Hz to 1 MHz, and temperature range from RT to 600°C. These samples show strong frequency and temperature dependent dielectric relaxations. The power law dependence on a.c conductivity is evaluated. The effect of La 3 + substitution on dielectric, impedance and a.c conductivity is studied. The results obtained are interpreted in terms of the pluckering and on the consequent lattice distortion that is usually present in Bismuth Layer Structured Ferroelectrics. [ABSTRACT FROM AUTHOR]

The effect of lanthanum doping is studied on electromechanical properties of lanthanum doped sodium bismuth titanate. The ferroelectric system under investigation is Na 1/2 (La x Bi 1-x ) 1/2 TiO 3 ceramics, with x = 0, 0.1, 0.15 and 0.2. Dielectric and impedance studies have been carried out in the temperature region ranging from room temperature to 550°C and in the frequency range of 100 Hz to 1 MHz. The relaxation behaviour of the charge entities in the above samples is studied as a function of temperature. The structural phase transitions present in the samples showed interesting changes with composition frequency and temperature. Admittance measurements were carried out in the frequency range of 100 Hz to 13 MHz and in the temperature range of room temperature to 550°C. Combined impedance and admittance spectroscopy was used to analyze admittance data. The electromechanical parameters were calculated from the resonant and anti resonant frequencies obtained from vector admittance plots. The electromechanical coefficients for pure sodium bismuth titanate ceramic samples were found to be much larger than the reported values. And also, it is observed that the lanthanum doping decreased the values of electromechanical coupling coefficients. [ABSTRACT FROM AUTHOR]