Nimish H. Vasoya; Kiran G. Saija; Akshay R. Makadiya; Tushar K. Pathak; Urmila M. Meshiya; Pooja Y. Raval; Kunal B. Modi
Abstract
The compositional dependence of the real (ε') and imaginary (ε'') parts of complex dielectric permittivity (ε*) and loss tangent (tan d) for Mn0.7+xZn0.3SixFe2-2xO4 (x = 0.0, 0.1, 0.2 and 0.3) spinel ferrite series was investigated over wide frequency (f = 20 Hz to 1 MHz) and ...
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The compositional dependence of the real (ε') and imaginary (ε'') parts of complex dielectric permittivity (ε*) and loss tangent (tan d) for Mn0.7+xZn0.3SixFe2-2xO4 (x = 0.0, 0.1, 0.2 and 0.3) spinel ferrite series was investigated over wide frequency (f = 20 Hz to 1 MHz) and temperature (T = 300 K to 673 K) ranges. Frequency dependence of ε',ε'' and tan δ has been explained based on the two-layer model of dielectrics. The nonlinear relationship between ε'(f) and σ'(f) suggests multi-relaxation process and formation of a broad hump in ε'(f, T) plots indicates collective contributions from electrons and holes to the polarization. The scaling by normalized frequency (f/fc) and scaled frequency (f/σdc) are found successful for ε' in high-frequency regime only while scaling found successful for ε'' over the whole range of frequency. The suitability of various scaling parameters was also tested for the master curve generation. The co-existence of localized and delocalized relaxations is verified.
Moumita Khutia; Girish M. Joshi; Subhratanu Bhattacharya
Abstract
Polyvinyl alcohol (PVA) /Poly (tetrafluoroethylene) (PTFE)/Titanium oxide (TiO2) was prepared by ( 5, 10 and 15 wt %) TiO2 loading. The miscibility, thermal property and microstructure of the composites were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy ...
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Polyvinyl alcohol (PVA) /Poly (tetrafluoroethylene) (PTFE)/Titanium oxide (TiO2) was prepared by ( 5, 10 and 15 wt %) TiO2 loading. The miscibility, thermal property and microstructure of the composites were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The electrical relaxation dynamics including dielectric and electrical conductivity was examined as a function broadband of frequency and temperature. The dielectric data was analyzed via the electric modulus. The Maxwell-Wagner-Siller (MWS) effect corresponds to interfacial polarization at low frequency follows Arrhenius behavior. The α-mode relaxation is attributed to glass-rubbery transition in composites, obeys the Vogel- Taman-Fulcher (VTF) model. A slight bump was noted at relatively high temperature and high frequencies termed as Intermediate dipolar effect (IDE) obeys the Arrhenius behavior. Conductive mechanism was analyzed via AC conductivity spectra. However, DC conductivity follows Arrhenius equation. The overall studies confirm that the self relaxation mechanism of PVA/PTFE composites were modified by TiO2, offers the tuning conductivity as a function of the temperature which can be used in various electronic applications.
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.
Subhadarsani Sahoo; Dhiren K. Pradhan; R. N. P. Choudhary; B. K. Mathur
Abstract
The polycrystalline sample of (K0.5Bi0.5)(Fe0.5Nb0.5)O3 was synthesized by a high- temperature solid-state reaction technique. The material crystallizes in cubic structure at room temperature. The dielectric properties of the material were investigated in a temperature range from 30-200 ºC in the ...
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The polycrystalline sample of (K0.5Bi0.5)(Fe0.5Nb0.5)O3 was synthesized by a high- temperature solid-state reaction technique. The material crystallizes in cubic structure at room temperature. The dielectric properties of the material were investigated in a temperature range from 30-200 ºC in the frequency range (102–107 Hz). Impedance data is well fitted using proper equivalent circuit composed of a parallel resistance and capacitance in series with a parallel resistance, constant phase element and a capacitance. The compound shows a typical negative temperature coefficient of resistance type (NTCR) behavior like that of semiconductors. Modulus spectroscopy and dielectric conductivity formalism were employed to study dielectric relaxation phenomena in the material. The frequency dependence of conductivity is well fitted to Jonscher’s single power law.