D. D. Ramteke; H. C. Swart; R. S. Gedam
Abstract
The role Pr 3+ ions in the lithium borate glasses have been investigated by electrochemical impedance spectroscopy technique. The glasses were prepared by conventional melt quench technique with formula 27.5 Li2O-(72.5-X) B2O3-X Pr6O11 (where, X= 0.5, 1, 1.5 and 2). It is observed that the conductivity ...
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The role Pr 3+ ions in the lithium borate glasses have been investigated by electrochemical impedance spectroscopy technique. The glasses were prepared by conventional melt quench technique with formula 27.5 Li2O-(72.5-X) B2O3-X Pr6O11 (where, X= 0.5, 1, 1.5 and 2). It is observed that the conductivity of the glasses decreases with the addition of Pr 3+ ions which was correlated with increase in the activation energy of the glasses. The observed conductivity behavior in the present study is mostly govern by the Pr 3+ as it has higher molecular weight as compared to other component in the glass system. Insight of conduction mechanism was revel by the scaling of modulus and conductivity data of the prepared samples. Scaling confirms that the conduction mechanism is compositional dependent. Based on the present study it is possible to use and modified these glasses as an insulating and dielectric material.
Shweta Thakur; Seema Sharma;Ashutosh Tiwari; Radheshyam Rai
Abstract
Polycrystalline samples of (K0.45Na0.45Li0.1NbO3)1-x-(Ba0.96La0.04Ti0.815Mn0.0025 Nb0.0025Zr0.18 O3)x ceramics (where x = 0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by using a high temperature solid state reaction technique. The XRD patterns of the BLTMNZ doped KNLN at room temperature with x = 0.7 have ...
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Polycrystalline samples of (K0.45Na0.45Li0.1NbO3)1-x-(Ba0.96La0.04Ti0.815Mn0.0025 Nb0.0025Zr0.18 O3)x ceramics (where x = 0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by using a high temperature solid state reaction technique. The XRD patterns of the BLTMNZ doped KNLN at room temperature with x = 0.7 have pure pervoskite phase with tetragonal structure at room temperature and have maximum value of dielectric constant at x = 0.9. Detailed studies of dielectric and impedance properties of the materials in a wide range of frequency (100Hz–1MHz) and temperatures (30 – 500 o C) showed that properties are strongly temperature and frequency dependent. The plots of Zʹʹ and Mʹʹ versus frequency at various temperatures show peaks in the higher temperature range (>300 o C). The compounds show dielectric relaxation, which is found to be of non-Debye type and the relaxation frequency shifted to higher side with increase in temperature. The Nyquist plot and conductivity studies showed the NTCR character of samples.
M. Belal Hossen; A.K.M. Akther Hossain
Abstract
The influence of Al 3+ substitution on the microstructure and impedance spectroscopy of Ni0.27Cu0.10Zn0.63AlxFe2-xO4 has been studied by scanning electron microscopy and impedance analyzer where the formation of the material in the spinel crystal structure was initially confirmed by X-ray structural ...
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The influence of Al 3+ substitution on the microstructure and impedance spectroscopy of Ni0.27Cu0.10Zn0.63AlxFe2-xO4 has been studied by scanning electron microscopy and impedance analyzer where the formation of the material in the spinel crystal structure was initially confirmed by X-ray structural analysis with room temperature data. The surface morphology indicates well defined grains separated by grain boundaries and with Al substitution average grain size decrease from 17 μm to 12 μm and zinc losses as well. The complex-plane impedance spectra indicate that the material can be represented by two semicircular arcs (its tendency) which corresponds to the bulk and the grain boundary resistance at high and low frequencies respectively. With Al substitution both grain and grain boundary resistance increases from 7.48 kΩ to 15.62 kΩ and 92.34 kΩ to 192.46 k respectively. Electric modulus spectra reflect the contributions from grain and grain boundary effects: the large resolved semicircle arc caused by the grain effect and the small poorly resolved semicircle arc was attributed to the grain boundary.
Mayank Pandey; Girish M. Joshi; Kalim Deshmukh; Jamil Ahmad
Abstract
Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) based polymer electrolytes for different loading wt% of CdCl2 were prepared by solution casting. The structural complexation was confirmed and interlayer spacing (d) was evaluated by using X-ray diffraction (XRD) study. The chemical bonding between ...
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Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) based polymer electrolytes for different loading wt% of CdCl2 were prepared by solution casting. The structural complexation was confirmed and interlayer spacing (d) was evaluated by using X-ray diffraction (XRD) study. The chemical bonding between polymer and salt was identified by using Fourier transform infrared spectroscopy (FTIR) technique. The FTIR peak at 3402.43 cm -1 in addition of PVP in PVA/CdCl2 composite demonstrates the grafting between two polymers. The presence of ionic bright channels and variation in morphology for different loading wt% of CdCl2 was confirmed by scanning electron microscope (SEM) and was also verified by Atomic force microscopy (AFM) micrographs. The analysis of impedance spectroscopy represented by semicircular pattern is driven by conduction mechanism and correlated with electrical conductivity. The enhanced AC conductivity of polymer electrolyte is directly proportional to frequency (50Hz-1MHz). The maximum value of DC conductivity 1.65x10 -5 S/m evaluated from Arrhenius plots and attribute to high mobility of free charges at higher temperature. The evaluated results of structural, morphological and electrical properties of present composites make the present research good for electrochemical devices.
S. Behera; Piyush R. Das; B. N. Parida; P. Nayak; R. N. P Choudhary
Abstract
The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning ...
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The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning electron microscope. The temperature variation of dielectric constant shows dielectric anomaly in the sample. Study of electrical properties (impedance, conductivity, etc.,) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc) and electrical parameters. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity.
Anita Mekap; Piyush R. Das; R. N. P. Choudhary
Abstract
The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was ...
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The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was recorded at room temperature using a scanning electron microscope (SEM). Detailed studies of dielectric properties (εr, tan δ) and impedance parameters of the material provide an insight into the electrical properties and understanding of types of relaxation process occurred in the material. Temperature variation of dc conductivity shows that this compound exhibits negative temperature coefficient of resistance (NTCR) and frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.
Prashant Ambekar; Jasmir Randhawa; Kamal Singh
Abstract
In the present investigation, LiNbO3 dispersed Li2CO3 composite of varying volume fraction is prepared. Its validity of placement in ionic conductor is verified by determining ionic transference number by Wagner’s dc polarization technique and bulk electrical conductivity is estimated with complex ...
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In the present investigation, LiNbO3 dispersed Li2CO3 composite of varying volume fraction is prepared. Its validity of placement in ionic conductor is verified by determining ionic transference number by Wagner’s dc polarization technique and bulk electrical conductivity is estimated with complex impedance spectroscopy. Two different conduction mechanisms are revealed by the complex impedance plots at low and high frequencies. Significant enhancement in the ionic conductivity has resulted due to enhancement in vacancies at the grain boundary interface facilitated by the localized polarization of carbonate grains due to the presence of ferroelectric phase. The effect on electrode kinetics is studied by characterizing an electrochemical CO2 gas sensor with this composite as sensing electrode which showed significant reduction in response time and recovery time (<10 sec). The use of such composite systems will benefit the development of fast electrochemical devices.
U. Ahmadu; S. Tomas; S. A. Jonah; A. O. Musa; N. Rabiu
Abstract
Two RC model circuits are connected in series in order to analyze the electrical and dielectric behaviour of mixed alkali Na0.25Li0.75Zr2(PO4)3 NASICON compound. However, the data obtained could best be described by one RC circuit representing the grain boundary resistance () and capacitance () in the ...
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Two RC model circuits are connected in series in order to analyze the electrical and dielectric behaviour of mixed alkali Na0.25Li0.75Zr2(PO4)3 NASICON compound. However, the data obtained could best be described by one RC circuit representing the grain boundary resistance () and capacitance () in the temperature and frequency range 300-600 K and 300 kHz to 1GHz, respectively. The values of the grain boundary activation energy obtained by fitting to the Arrhenius equation in a plot is ~ 0.40 eV, which is close to the bulk activation energy for electrical conduction. The maximum conductivity obtained is 0.3 S/m at 590 K. A non Debye character was observed in the dielectric permitivity in its frequency dependence. However, the temperature dependence of followed a linear behaviour at low temperatures and frequencies but decreased at higher temperatures. Complex non linear least squares fitting of impedance data using a composite circuit shows good fitting results with relative standard deviation less than 0.2 for all the free parameters which is indicative of the accuracy of data obtained. Similar good fitting results, using a generic battery model, suggest the applicability of the material in rechargeable lithium ion batteries.