Investigation of Complex Impedance and Modulus Properties of Nd Doped 0.5BiFeO3-0.5PbTiO3 Multiferroic Composites

0.5BiNdxFe1-xO3-0.5PbTiO3 (x=0.05, 0.10, 0.15, 0.20) composites were successfully synthesized by a solid state reaction technique. At room temperature X-ray diffraction shows tetragonal structure for all concentrations of Nd doped 0.5BiFeO3-0.5PbTiO3 composites. The nature of Nyquist plot confirms the presence of bulk effects only for all compositions of Nd-doped 0.5BiFeO3-0.5PbTiO3 composites. The bulk resistance is found to decreases with the increasing in temperature as well as Nd concentration and exhibits a typical negative temperature coefficient of resistance (NTCR) behavior. Both the complex impedance and modulus studies have suggested the presence of non-Debye type of relaxation in the materials. Conductivity spectra reveal the presence of hopping mechanism in the electrical transport process of the materials. The activation energy of the composite increases with increasing Nd concentration and were found to be 0.28, 0.27, 0.31 and 0.32eV for x=0.05, 0.10, 0.15, 0.20 respectively at 200-275 oC for conduction process.Comment: 22 pages, 12 figures, 2 tables, 34 Referenc

Research Letter Complex Impedance Spectroscopic Properties of Ba 3 V 2 O 8 Ceramics

The polycrystalline sample of Ba 3 V 2 O 8 was prepared by a high-temperature solid-state reaction technique. The effect of temperature on impedance parameters was studied using an impedance analyzer in a wide frequency range (10 2 -10 6 Hz). The real and imaginary parts of complex impedance trace semicircles in the complex plane. The temperature-dependent plots reveal the presence of both bulk and grain boundary effects above 125 • C. The bulk resistance of the material decreases with rise in temperature. This exhibits a typical negative temperature coefficient of resistance (NTCR) behavior of the material. The modulus analysis suggests a possible hopping mechanism for electrical transport processes of the material. The nature of variation of dc conductivity suggests the Arrhenius type of electrical conductivity

Transport phenomena and conductivity mechanism in Sm doped Bi4V2−xSmxO11 ceramics

The polycrystalline samples of Sm doped Bi4V2−xSmxO11 with x = 0.05, 0.10, 0.15 and 0.20 ceramics were prepared by using solid-state reaction technique. The structural characterization of the prepared samples were confirmed by X-ray powder diffraction (XRD) and showed an orthorhombic and monoclinic phase. The nature of Nyquist plot confirms the presence of both grain and grain boundary effects for all Sm doped compounds. The grain resistance decreases with rise in temperature for all the samples and exhibits a typical negative temperature co-efficient of resistance (NTCR) behavior. The ac conductivity spectrum obeys Jonscher's universal power law. The modulus analysis suggests a possible hopping mechanism for electrical transport processes of the materials. The nature of variation of dc conductivity suggests the Arrhenius type of electrical conductivity for all the samples

Investigation on structural, dielectric and ferroelectric properties of samarium-substituted BiFeO3–PbTiO3 composites

The polycrystalline samples of 0.8BiSmxFe1−xO3–0.2PbTiO3 (x=0.05,0.10,0.15 and 0.20) were prepared by using the conventional solid-state reaction technique and sintered at high temperature (850∘C). X-ray diffraction (XRD) confirms the distorted rhombohedral crystal structure for all the composites at room temperature. The surface morphology was checked by field-emission scanning electron microscope (FESEM) technique and homogeneous mixing of the components was confirmed by energy-dispersive analysis of X-ray (EDAX). The detailed study of dielectric properties of the composites reveals an increasing nature of dielectric constant (εr) and loss tangent (tanδ) with the increase of temperature due to thermal activation. The Arrhenius plots of temperature dependence of AC conductivity yield the activation energy within the material at high-temperature range. The ferroelectric study shows that the remnant polarization decreases with the increase of Samarium (Sm) concentration

Dielectric, electrical and magnetic properties of La doped BiFeO3-PbZrO3 composites

The composites of 0.5(BiLayFe1-yO3)-0.5(PbZrO3) y = 0.05, 0.10, 0.15 and 0.20] were synthesized through solid-state reaction technique. The X-ray diffraction data confirms the rhombohedral structure of the above systems at room temperature. From the SEM, it is shown that the grains were inhomogeneously distributed over the surface of the composites. The dielectric constant and loss of the composites increased with rise in temperature. The low remanent polarization (0.005, 0.006, 0.008, and 0.004 mu C/cm(2)) for 0.5(BiLayFe1-yO3)-0.5(PbZrO3) y = 0.05, 0.10, 0.15 and 0.20] respectively shows the weak ferroelectric nature. The Nyquist plot showed the contribution of bulk effect and slight indication of grain boundary effect. The presence of temperature dependent relaxation process occurs in the material. The activation energies calculated from the ac conductivity using least square fitting. The dc and ac conductivity increases with rise in temperature. The ac conductivity spectrum obeyed Johnscher universal power law. The low remanent magnetization was found to be 0.010, 0.009, 0.008 and 0.005 emu/gm for 0.5(BiLayFe1-yO3)-0.5(PbZrO3) y = 0.05, 0.10, 0.15 and 0.20] respectively

IMPEDANCE CHARACTERISTICS of La3/2Bi3/2Fe5O12 CERAMICS

Polycrystalline La3/2Bi3/2Fe5O12 (LBIO) compound was prepared by a high-temperature solid-state reaction technique. The complex impedance of LBIO was measured over a wide temperature (i.e., room temperature to 500 C) and frequencies (i.e., 10(2)-10(6) Hz) ranges. This study takes advantage of plotting ac data simultaneously in the form of impedance and modulus spectroscopic plots and obey non-Debye type of relaxation process. The Nyquist's plot showed the presence of grain effects in the material at high temperature. The ac conductivity spectrum was found to obey Jonscher's universal power law. The dc conductivity was found to increase with rise in temperature. The activation energy of the compound was found to be 0.24 and 0.51 eV in the low and high-temperature region, respectively, for conduction process

Complex Impedance Spectroscopic Properties of BaVO Ceramics

The polycrystalline sample of Ba3V2O8 was prepared by a high-temperature solid-state reaction technique. The effect of temperature on impedance parameters was studied using an impedance analyzer in a wide frequency range (102-106 Hz). The real and imaginary parts of complex impedance trace semicircles in the complex plane. The temperature-dependent plots reveal the presence of both bulk and grain boundary effects above 125∘C. The bulk resistance of the material decreases with rise in temperature. This exhibits a typical negative temperature coefficient of resistance (NTCR) behavior of the material. The modulus analysis suggests a possible hopping mechanism for electrical transport processes of the material. The nature of variation of dc conductivity suggests the Arrhenius type of electrical conductivity

Dielectric and impedance properties of Nd3/2Bi3/2Fe5O12 ceramics

The polycrystalline sample of Nd3/2Bi3/2Fe5O12 was prepared by a high- temperature solid-state reaction technique. Preliminary X-ray structural analysis exhibits the formation of a single-phase tetragonal structure at room temperature. Microstructural analysis by scanning electron microscopy shows that the sintered sample has well defined grains. These grains are distributed uniformly throughout the surface of the sample. Detailed studies of dielectric response at various frequencies and temperatures exhibit a dielectric anomaly at 400 A degrees C. The electrical properties (impedance, modulus and conductivity) of the material were studied using a complex impedance spectroscopy technique. These studies reveal a significant contribution of grain and grain boundary effects in the material. The frequency dependent plots of modulus and the impedance loss show that the conductivity relaxation is of non-Debye type. Studies of electrical conductivity with temperature demonstrate that the compound exhibits Arrhenius-type of electrical conductivity. Study of ac conductivity with frequency suggests that the material obeys Jonscher's universal power law