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In our earlier studies we have shown procedure for the estimation of activation energy and relaxation times directly from the dielectric and AC conductivity data simultaneously dependant on T and ω using modified Lorentz equation instead of well-known Arrhenius, modified Arrhenius and Vogel-Fulcher laws. In the present paper we have carried out similar experimental and simulation studies on the dielectric and AC conductivity data using modified Lorentz equations on the ceramic compound (Ba0.997Pr0.003TiO3). The obtained results on the activation energy and relaxation times are presented in this paper. [ABSTRACT FROM AUTHOR]

The experimental and simulation of dielectric, AC resistivity and dielectric resonance and anti-resonance data on (Na0.5Bi0.5)(NdxTi1-2xNbx)O3] ceramics were carried out using modified Lorentz equations as proposed by us instead of well know and generally applied laws like Arrhenius law and formulas on piezoelectricity to obtain activation energy, relaxation time, piezoelectric charge constant and voltage constant directly from the experimental data. The piezoelectric charge constant (d33) evaluated from the modeling are 864.64 p.m/V and 122.40 p.m/V; whereas the piezoelectric voltage constant (g33) are 10.88 p.m2/C and 8.55 p.m2/C for x = 0.0125 and 0.025 ceramic samples, respectively. [ABSTRACT FROM AUTHOR]

Samarium modified SrBi4-xSmxTi4O15 (x = 0, 0.13, 0.43 and 0.78) ferroelectric ceramics of Aurivillius family were prepared by conventional solid state reaction method. X-ray diffraction studies confirm the formation of a single-phase. Microstructural images show randomly oriented palate-like structure. Broad dielectric peaks were found to obey the modified Curie-Weiss law. The overall inherent ferroelectric nature was explained on the basis of the Avrami model. Furthermore, with increasing the Sm3+ content, the grain morphology and diffusive parameters have shown a comprehending impact on the ferroelectric (hysteresis) behavior. [ABSTRACT FROM AUTHOR]

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]

In the present study, simulation of polarization data using modified Glazounov equation (T & E simultaneously) of Barium Titanate based normal and relaxor ferroelectrics (i.e. BaTiO3 and Ba(NdxTi(1-2x)Nbx)O3) as proposed by us was carried out. These materials were prepared through sol-gel and solid state double sintering route. Modified Glazounov equation describes and model the experimental PE data in terms of dipole moment and activation energy for thermally activated dipoles present the ceramic materials. This equation best fit to the experimental PE data. The increase and decrease of activation energy with temperature and composition was attributed to the degree of disorderness of dipoles. [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]

Variation of tolerance factor was observed with doping of Sr and Bi at A and B sites respectively and independently in BaTiO3 compound. Stability of NBT based compositions is varied with the substitution of Ba content in A-site and alters with the concentration. Combining with the electronegativity difference and octahedral factor of ABO3 structure, regularities governing the formation and the stability of perovskite type compounds are discussed. According to the results of BST and BBT series both dopants are reduce the tolerance factor and increase the distortion within the lattice of ABO3-type perovskite, the experience tolerance factor value and experience electronegativity difference value to form stable perovskite compound were obtained. [ABSTRACT FROM AUTHOR]

AC conductivity studies were performed on the Na(0.5-x)KxBi(0.5-x)DyxTiO3 ceramics (x = 0.0125, 0.025 & 0.05) prepared through solid state reaction method. The frequency and temperature response of the conductivity is interpreted in terms of the jump relaxation model. Stress and temperature induced modulus resonance and anti-resonance behaviour was observed indicating electromechanical effect in the present ceramic materials. The electromechanical coupling factor have been found to be above 99.95% and is found to increase with increase of x. Value of d33 for x = 0.0125 sample is found to be 23.24 nm.V−1 and it decreases with increase of x. [ABSTRACT FROM AUTHOR]

Ba1-xRexTiO3 ceramics (Re = Nd&Pr with x = 0.002 & 0.004) were prepared through microwave sintering route using 5% SiO2 as sintering aid. The dielectric, impedance and DC resistivity studies were carried out over a wide range of temperature. From dielectric studies, it is observed that the transition temperature increased with the substitution of rare earth ions. The room temperature dielectric constant for the Nd (x = 0.002) doped barium titanate is higher when compared to other compositions and the value is 13,600.28. Impedance studies revealed relaxation behaviour. In the present study grain, grain boundary and sample-electrode effects were separated out by using Cole-Cole data. From the DC resistivity studies, it is observed that Pr (x = 0.004) doped barium titanate ceramic showed one order of magnitude PTCR effect. [ABSTRACT FROM AUTHOR]

[Ba(Nd0.1Ti0.8Nb0.1)O3]0.40[Na0.5Bi0.5TiO3]0.50[CaTiO3]0.10 ceramic samples were prepared through solid state sintering route. Impedance and dielectric studies were carried out on the prepared ceramic samples. Impedance and dielectric relaxor behaviour was observed. Grain and grain boundary effects are resolved by equivalent circuit modelling of experimental Cole-Cole data. Electromechanical studies are also carried out on the ceramic samples. Broad resonance and antiresonance peaks have been observed in the modulus data. The values thickness and effective mode of electromechanical coupling factors at 623 K are found to be 0.99983 and 0.99980 respectively. The value of d33 at 673 K and 773 K are found to be 40.32 nm.V-1and 6.44 nm.V-1 respectively. [ABSTRACT FROM AUTHOR]

(100-x) BaTiO3(BT)-(x) CoFe2O4(CFO) (X = 10, 20 and 30 wt%) composites were prepared through conventional solid state reaction method by mixing two individual phases by weight. Structure and surface morphology of the composites were observed using X-ray diffraction and Scanning electron microscopy respectively. Polarization study of the BT-CFO composites was done by measuring the polarization (P) against the electric field (E) up to 30 KV/cm, pattern observed showed good ferroelectric behaviour with Pmax= 4.10 µC/cm2for BT-CFO/90-10. In order to estimate the effect of magnetic phase on ferroelectric nature of BT, dielectric and magnetoelectric measurements were also done on the composites and are presented here. [ABSTRACT FROM PUBLISHER]

Ferroelectric ceramic materials NaxK1-xNbO3(NKN), with x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0 are synthesized by solid state double sintering method. The synthesized materials are characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), Differential scanning calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR). The x-ray diffraction studies indicate orthorhombic structure except for x = 0.4 (which has monoclinic structure). The SEM micro-graphs indicate a gradual change in the morphology of the samples. Growth of microfibers is observed in x = 0.5 samples. For higher compositions the microfiber morphology is changed.DSC of the samples showed phase transitions. Dielectric constant versus temperature plots indicated ferroelectric to paraelectric phase transitions. The complex impedance plots in higher temperature range are single semi-circles. The equivalent circuits contain parallel combinations of resistance and capacitance elements. [ABSTRACT FROM AUTHOR]

Bismuth layered structure ferroelectric materials of Aurivillius family have been attracted on account of their inherent-ferroelectric properties. Rare earth modified two layered compound, namely, Bi3TiNbO9has been found to be a relaxor ferroelectric material, and therefore much attention is being concentrated to enhance the dielectric properties with different modifications. In view of this, Sm-modified novel ceramic(Bi2SmTiNbO9) was prepared by the conventional solid-state reaction method. Impedance spectroscopic measurements were made as a function of frequency at different temperatures. Electrical studies were also made, and the results were corroborated to the Raman spectroscopic data. [ABSTRACT FROM AUTHOR]

Bismuth titanate (BT-‘Bi4Ti3O12’) is one of the extensively studied materials of the Bismuth layered structure ferroelectric (BLSF) family for its large spontaneous polarization along c-axis. In the present investigation, we have synthesised SmxBi4-xTi3O12(x = 0.37, 0.57, 0.72) ceramics using the conventional solid-state reaction method. The dielectric anomaly was observed near 450°C. Well-broad hysteresis loops were observed above room temperature up to 100°C. The coercive field (Ec) and consistent remanent polarization (Pr) values with temperature, compared to BT, indicates that the title compound has good promising ferroelectric-nature. This phenomenon is attributed to the easy recovery of defects (such as oxygen vacancies) accumulated at grain-interfaces, above room temperature, resulting in to well-hysteresis behaviour. The results were further confirmed with remanent polarization (2 Pr vs. temperature) plots. [ABSTRACT FROM AUTHOR]

[BaNd0.1Ti0.8Nb0.1O3]0.65[Na0.5Bi0.5TiO3]0.25[BaZrO3]0.10(BNNT-NBT-BZ) ceramic is prepared through solid state sintering method. The dielectric, impedance and DC resistivity studies are carried out as a function of temperature. Dielectric and impedance studies revealed relaxor behaviour. DC resistivity studies revealed PTCR effect in the present ceramic. Capacitance resonance and anti-resonance studies in free and clamped state are carried out over a wide range of frequency at room temperature. The values of Kt, Keffand d33at room temperature are 0.112, 0.105 and 1.003 pm.V−1respectively for ceramic sample studied under free state, whereas for the samples studied under clamped state the values are 0.667, 0.629 and 26.410 pm.V−1respectively. Stress and temperature induced modulus resonance and anti-resonance studies are carried out over a wide frequency range and temperature. The values of Kt, Keffand d33at 723K are 0.99926, 0.99911 and 14.188 nm.V−1respectively. [ABSTRACT FROM AUTHOR]

Modified Lorentz equation which was proposed by us is used to model the resonance and anti-resonance behaviour in free and clamped state of [Ba(Nd0.1Ti0.8Nb0.1)O3]1-x[(Na0.5Bi0.5)TiO3]xpiezoelectric ceramics. The modified Lorentz equation gives information about the static dielectric constant, infinite dielectric constant, polarizability, piezoelectric charge constant and piezoelectric voltage constant. The modified Lorentz equation is found to best fit to the experimental data. The validity of modified equation can be known from the regression value obtained. The order of polarizability, piezoelectric charge constant and piezoelectric voltage constant are of the order of 10−37(F.m2), 10−9m/V and 10−11m2/C respectively for the present ceramics. The piezoelectric charge constant decreased with the increase of x value. Higher piezoelectric charge constant was observed for the ceramic with x = 0.40 in clamped state when compared to other composition in free and clamped state and the value is 2.288×10−9m/V. The piezoelectric voltage constant decreased with the increase of x value. Lowest piezoelectric voltage constant was observed for the ceramic with x = 0.40 in clamped state and the value is 1.030 ×10−11m2/C. Ceramic composition with higher x value and which were studied in clamped state shows better piezoelectricity. [ABSTRACT FROM PUBLISHER]

[BaNd0.1Ti0.8Nb0.1O3]0.40[Na0.5Bi0.5TiO3]0.50[CaTiO3]0.10ceramic was prepared through solid state double sintering method. The XRD results indicate that the ceramic sample have a cubic structure at room temperature. The average grain size was found to be around 4–6 μm. Dielectric studies revealed that the present materials exhibit relaxor behaviour. From piezoelectric studies, it is observed that the resonance and anti-resonance peaks was broad for ceramic sample studied under clamped state when compared to ceramic sample studied under free State. The values of Kt& Keffat room temperature for ceramic samples studied under clamped state were 0.751, 0.718 respectively. Modified Lorentz equation was used to characterize the dielectric and resonance & anti-resonance behaviour and was found to best fit to the experimental data. The activation energy for thermally activated orientation of dipoles was in the range 80–90 μeV. The piezoelectric charge constant (d33) and piezoelectric voltage constant (g33) for the ceramic sample studied under free state are 1.359 × 10−9(m/V) and 2.526 × 10−11(m2/C) respectively. [ABSTRACT FROM PUBLISHER]

[Ba(Nd0.1Ti0.8Nb0.1)O3](1-y)[Na0.5Bi0.5TiO3]yceramics were prepared through solid state sintering (CS) and microwave sintering (MWS) route. The XRD results indicate that the ceramic samples have a cubic structure at room temperature. The dielectric, electromechanical and piezoelectric properties were also investigated. Relaxor behaviour was observed for the present ceramic samples prepared through both the sintering routes. The degree of diffusiveness of phase transition and relaxor behaviour are more for CS ceramic when compared to MWS ceramic with y = 0.40. From modulus measurements, the values of Kt, Keffand d33at 623 K were 0.99983, 0.99980 and 5.273 nm.V−1respectively for MWS ceramic with y = 0.25. The piezoelectric constant (d33) decreased with the increase of temperature. The d33values are higher for the microwave sintered ceramic samples when compared to conventional sintered ceramic samples. [ABSTRACT FROM PUBLISHER]

Modified Lorentz equation is proposed to describe the resonance and anti-resonance behaviour of piezoelectric ceramics. It is applied to Ba(NdxTi1−2xNbx)O3, (Na0.5Bi0.5)(NdyTi1−2yNby)O3and Sr1−2zNazNdzBi4Ti4O15piezoelectric ceramics by non linear curve fitting to experimental data to check its validity. The validity is checked from the regression values obtained. The static dielectric constant, infinite dielectric constant, polarizability, piezoelectric charge constant and piezoelectric voltage constant obtained from the non linear curve fitting to experimental data by using modified Lorentz equation have reasonable values. The above modified equation may also be used to describe the resonance and anti-resonance behaviour of other piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Lead free piezoelectric ceramic Ba1-xRexTiO3(Re = Ce and Pr withx= 0.003) were prepared through microwave sintering route using 5% SiO2as sintering aid. The dielectric, impedance and piezoelectric properties were studied over a wide range of temperature. Pr doped barium titanate showed higher value of dielectric constant around 15,099. The electromechanical coupling factors at 225°C are 0.9985 and 0.9978 for Ce and Pr doped barium titanate ceramics respectively. The d33values for Ce and Pr doped barium titanate ceramics at 225°C are 368 nm.V−1and 470 nm.V−1respectively. The d33value decreased with the increase of temperature and the values at 600°C are 10 nm.V−1and 8 nm.V−1for Ce and Pr doped barium titanate ceramics respectively. [ABSTRACT FROM PUBLISHER]

A new equation is proposed to describe the simultaneous temperature and frequency dependence of dielectric constant and impedance of relaxor ferroelectric compounds. It is applied to Ba(NdxTi1-2xNbx)O3relaxor compounds by non linear curve fitting to experimental data to check its validity in terms of fitted parameters obtained which have logical values. The validity can also be known from the regression value. This new equation may be used to characterize the dielectric behaviour of other relaxor ferroelectric compounds. [ABSTRACT FROM AUTHOR]

BaBixTi(1−x)O3−δceramics are prepared by sol-gel reaction method with different x values (x = 0, 0.05 and 0.1). Structural property of all compositions is studied by XRD and compared with the standard patterns (ICSD card 27977). The crystalline size increases with increase the Bi concentration. The temperature dependence of impedance of BaBixTi1−xO3 (x = 0, 0.05, 0.1) compositions is studied in the frequency range of 100 Hz-1M Hz. Relaxation times (τ) are studied for the different BaBiO3concentrations doped into barium titanate ceramics. The impedance characteristics of the laminated type graded composite materials of BaTiO3+ Ba0.95Bi0.05TiO3+BaTiO3and BaTiO3+ Ba0.90Bi0.1TiO3+BaTiO3are also studied. The impedance data is analyzed using established models and equivalent circuit parameters are evaluated. The equivalent circuits obtained consist of series or parallel combination of a resistance and a constant phase elements. The results are interpreted in terms of materials properties. [ABSTRACT FROM AUTHOR]