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Showing 6 results for Conductivity

N. Maragani, K. Vijaykumar,
Volume 14, Issue 4 (12-2017)

Ion conducting gel polymer electrolytes based on poly acrylonitrle (PAN) complexed with different weight percent ratios of Sodium Fluoride (NaF) salt were prepared by using solution cast technique. Structural characterization was performed using X-ray diffraction (XRD) technique and Fourier transforms infrared (FTIR) spectroscope technique. From the X-rd results increase in amorphous phase with the increase of dopant salt concentration was observed. Fourier transform infrared (FTIR) spectroscopic analysis confirmed the complexation of the salt with the polymer matrix.  Electrical conductivity was measured that the magnitude of ionic conductivity increased with the increase in the salt concentration as well as temperature. The surface morphology was observed by using Scanning Electron Microscope (SEM), the optical band gap measured from UV-Vis Spectroscopy. The sample containing 30 wt% of NaF exhibited the highest conductivity of 1.82x10-4 S cm-1 at 303K and 2.96x10-3 S cm-1 at 373K. The temperature dependence of ionic conductivity of these films followed Arrhenius relation. Transference number measurements were carried out to investigate the nature of the charge transport species in the polymer electrolyte systems. The transference number data showed that the charge transports in these systems are predominantly due to ions. Using these polymer electrolyte films, electrochemical cells were fabricated and their discharge characteristics were studied. Various cell parameters, such as open circuit voltage, short circuit current, power density and energy density were determined.

M. R. Ghaani, P. Marashi,
Volume 15, Issue 3 (9-2018)

Na super ionic conductive (NASICON) materials are ceramics with three-dimensional scaffolds. In this study, Li1.4Al0.4Ti1.6(PO4)3 with NASICON structure was synthesized by Pechini method. As a result, a sample having a total conduction of 1.18×10-3 S cm-1 was attained. In addition, various parameters were studied to obtain high value of conductivity, by optimizing the process. The optimization was made using L16 Taguchi based orthogonal array, followed by ANOM, ANOVA and stepwise regression. As a result, the optimum synthesis parameters can be obtained, while pH of the solution was adjusted to 7. The ratio between the concentration of citric acid to metal ions and ethylene glycol concentration stuck to 1 and 2.5, respectively. The best heat treatment can be carried out with a combination of pyrolysis at 600 ºC and sintering at 1000 ºC. 
G. Chandraprabha, T. Sankarappa, T. Sujatha,
Volume 15, Issue 4 (12-2018)

Polythiophene (PTh) and cobalt nanoparticles (Co-nps) were prepared by chemical oxidation and modified polyol processes respectively. Composites were made by mixing them in the proportions, PTh1-xCox; x = 0.1, 0.2, 0.3, 0.4, 0.5.  Morphology of the samples has been studied by SEM technique. Dielectric properties with temperature and frequency as variables were investigated. Dielectric constant and loss factor decreased with frequency and increased with temperature. AC conductivity was estimated from the dielectric data. Ac conductivity decreased with increase of Co-nps in the composites which indicates that electrically insulating effect has been induced by Co-nps. Small polaron hopping mechanism is found to be the conduction mechanism operated. Activation energy for ac conduction decreased with increase of frequency and weight percent of Co-nps in the composites.  Electric modulus was determined and its analysis leads to the estimation of dielectric relaxation time. Relaxation time decreased with increase of temperature for all the five composites. For the first time PTh-Co nanocomposites have been reported for dielectric properties and ac conductivity as a function of frequency and temperature.
Najwa Gouitaa, Lamcharfi Taj-Dine, Abdi Farid , Ahjyaje Fatima Zahra,
Volume 18, Issue 3 (9-2021)

      In this study we have synthesis the Zr substituted BaTi0.80Fe0.20O3 ceramics at different content of Zr from x=0.00 to 0.10 by using the solid-state route. The room temperature X-ray diffraction results confirmed the coexistence of the two tetragonal and hexagonal phases for x ≤ 0.050 of Zr content. While above 0.050 the hexagonal phase disappears in benefit of tetragonal phase. The Raman results confirmed the formation of these phases obtained with XRD. The scanning electron micrographs consist of both spherical and straight grain forms for x=0.000 to 0.075, and only spherical grain form for x=0.100 attributed to the tetragonal phase. Also, the grain size increases accompanied with a decrease in density of ceramics with increasing Zr content up to 0.050 then decreases accompanied with an increase in density. Detailed studies of dielectric permittivity measurement have provided a presence of two anomalies Te and TR-O at different temperatures, with a relaxation phenomenon and diffuse behavior which is very important for ceramic at x=0.075 of Zr content. The dielectric permittivity values of the two anomalies of Zr substituted BaTi0.80Fe0.20O3 ceramics increase with increase of Zr content and the dielectric loss is minimal at x=0.100 of Zr content. The conductivity increases with the increasing of Zr substitution from 0.025 to 0.075 levels while for x = 0.100 the dielectric conductivity decreases.  And the Cole-Cole analysis indicates a negative thermal resistivity coefficient (NTCR) behavior of these materials and an ideal Debye-type behavior.

Mala Siddaramappa, Haraluru Kamala Eshwaraiah Latha, Haraluru Shankaraiah Lalithamba, Andi Udayakumar,
Volume 18, Issue 4 (12-2021)

Indium tin oxide (ITO) nanoparticles were synthesized by green combustion method using indium (In) and tin (Sn) as precursors, and Carica papaya seed extract as novel fuel. This paper highlights effect of tin concentration (5%, 10% and 50%) on microstructural, optical and electrical properties of ITO nanoparticles (NPs). The indium nitrate and tin nitrate solution along with the fuel were heated at 600 °C for 1 h in muffle furnace and obtained powder was calcinated at 650 °C for 3 h to produce ITO NPs. The above properties were investigated using XRD, FTIR, UV-Vis spectroscopy, SEM, TEM and computer controlled impedance analyser. The XRD, SEM and TEM investigations reveals the synthesized NPs were spherical in shape with an increase in average grain size (17.66 to 35 nm) as Sn concentration increases. FTIR investigations confirms the In-O bonding. The optical properties results revealed that the ITO NPs band gap decreased from 3.21 to 2.98 eV with increase in Sn concentration. The ac conductivity of ITO NPs was found to increase with increase in Sn concentration. These synthesised ITO NPs showed the excellent properties for emerging sensor and optical device application.
Nihel Hsouna, Mohsen Mhadhbi, Chaker Bouzidi,
Volume 19, Issue 1 (3-2022)

Phosphate glass with different Al2O3 and Na2CO3 compositions [80NaH2PO4-(20-x) Na2CO3-xAl2O3 with a step from 0 to 4] were prepared through melt quenching technique furnace at 900 °C. In order to determine the structure and microstructure modification of the samples after heat treatment the IR and Raman spectroscopy were performed. The X-ray diffraction (XRD) result shows an amorphous character of the prepared glass. The result obtained by differential scanning calorimetry (DSC) reveals a good thermal stability in the temperature range of 25 to 400 °C. The impedance Nyquist diagrams were investigated and modeled by resistors and constant phase elements (CPE) equivalent circuits. These measurements show a non-Debye type dielectric relaxation. Both AC and DC conductivity, dielectric constant, and loss factors were determined. Thermal activation energies were also calculated. A changes in the electrical conductivity and activation energy depend upon the chemical composition were observed. Also, a transition in the conduction mechanism from ionic to mixed ionic polaronic was noted. In the same line, electrical modulus and dielectric loss parameters are also deduced. Their frequency and temperature dependency exhibited relaxation behavior. Likewise, activation energies value obtained from the analysis of M’’ and those obtained from the conductivity are closes, which proves the optimal character of the preparation conditions.

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