Keywords : AC conductivity


Structural, Optical and dielectric properties of Sr doped LaVO4

Khalid Sultan; Rubiya Samad; Feroz A. Najar; Shohaib Abass; Saima Jahan; Mudasir Rashid Rather; M. Ikram

Advanced Materials Letters, 2021, Volume 12, Issue 6, Pages 1-6
DOI: 10.5185/amlett.2021.061640

Polycrystalline bulk samples of chemical composition La1-xSrxVO4 (x = 0.0, 0.1, 0.3, 0.5) were prepared by solid state reaction method. The Morphology and structure wascharacterised by Scanning Electronic microscopy and powder X-ray diffraction respectively. All the prepared material were single-phase and co-doped ions were successfully incorporated in LaVO4 lattice. The EDAX spectrum shows that the percentage composition of given elements in the proposed formula was in good agreement with the corresponding values determined experimentally. The Raman spectra of LaVO4 reflect the VO4 type structure that consists of four different V–O bands. The prominent Raman band at about 860 cm -1 can be assigned to the symmetric V–O stretching mode while the weak Raman band at 792 cm -1 is assigned to antisymmetric V–O stretching mode. With increase in Sr doping, optical band gap was found to decrease resulting in increase in conductivity. The dielectric constant as well as dielectric loss shows a relaxor type of behaviour for higher doping concentration which can be attributed to the chemical pressure induced in LaVO4 with the doping of Sr ions. The studies performed on ac conductivity identifies that the conduction mechanism follows the charge hopping between localised states and follow the small polaron conduction.

Preparation and Characterization of Nickel Ferrite Nanoparticles via Sol-gel Method

Savithri. M. Nampoothiri; Viji. C; E. M. Mohammed; Robin Francis

Advanced Materials Letters, 2020, Volume 11, Issue 2, Pages 28-31
DOI: 10.5185/amlett.2020.021473

Nickel ferrite (NiFe₂O₄) nanoparticles were synthesized using sol-gel method and the powdered samples were sintered at 100°C and 200°C. X-ray Diffraction (XRD) patterns were used to determine the structure of nickel ferrite nanoparticles. Obtained the lattice parameter from the XRD data and calculated the particle size using Debye- Sherrer formula. The details of the surface morphology of NiFe2O4 nanoparticles were studied by Scanning Electron Microscopic (SEM) analysis. The work aims at the investigation of the dielectric properties such as dielectric loss and permittivity of Nickel ferrite nanoparticles at various frequencies and temperatures. In addition, the ac conductivity of the nickel ferrite nanoparticles was studied.

Impedance Measurements Of Some Silver Ferro-phosphate Glasses 

Fathy Salman; Reda Khalil;Hany Hazaa

Advanced Materials Letters, 2016, Volume 7, Issue 7, Pages 593-598
DOI: 10.5185/amlett.2016.6175

Impedance measurements of (50-x)P < sub>2O5-xAgI-40Ag2O-10Fe2O3, [where x = 0, 15, 20, 25, 30, 35, 40 and 45 mol %] superionic glasses have been studied in the frequency range (500 Hz - 5 MHz) and in the temperature range 303-413 K. The frequency dependence of the total conductivity (σt) for the investigated samples was carried out at different ambient temperatures. The temperature dependence of ac conductivity σac(ω) and dc conductivity (σdc) were studied, where Arrhenius behavior has been observed for all the samples glass, and the corresponding activation energies ΔEac and ΔEdc, respectively have been obtained. The bulk conductivity (σb) of the samples has been carried out at different temperatures, from impedance plots, where the activation energy ΔEb can be obtained. From the frequency dependence of the ac conductivity of the investigated samples, σac(ω)=Aωs, the frequency exponent s and the maximum barrier height Wm have been deduced at different compositions. The results are interpreted in terms of the correlated barrier hopping (CBH), Funke, and Minami models.

SnO2 Nanoparticles Synthesis Via Liquid-phase Co-precipitation Technique 

G. T. Lamdhade; F. C. Raghuwanshi; R. M. Agrawal; V. M. Balkhande; T. Shripath

Advanced Materials Letters, 2015, Volume 6, Issue 8, Pages 738-742
DOI: 10.5185/amlett.2015.5877

The samples have been prepared in the form of pellets of SnO2 nanoparticles and synthesized via the liquid-phase co-precipitation technique. The ac electrical conductivity of samples is found to be frequency dependent. The dielectric constant increases with temperature and decreases with frequency of applied field. The semiconducting behavior of SnO2 nanoparticles have been studied from I-V characteristics. The characterization of samples has been studied by XRD, FESEM, UV-spectra and TG-DTA plot

Frequency And Temperature Dependent Impedance Study In 50% BaTiO3- 50% La0.7Sr0.3MnO3 Nanocomposite

Momin Hossain Khan;Sudipta Pal

Advanced Materials Letters, 2014, Volume 5, Issue 7, Pages 384-388
DOI: 10.5185/amlett.2014.05552

We report the impedance spectroscopy (IS) behavior of the ferroelectric- ferromagnetic (50% BaTi O3-50% La0.7Sr0.3MnO3) nano-composite prepared by sol-gel method. Frequency and temperature dependence of the complex impedance and conductivity has been measured over the temperature range 310 K-430 K. A distribution of relaxation times and decentralization of the semicircle has been observed from the Cole–Cole plots of real and imaginary parts of the complex impedance. Non-Debye type relaxation has been observed in the investigated composite system. An equivalent circuit has been constructed to describe the IS. Interestingly, a typical universal dielectric response in the frequency-dependent conductivity at different temperature has been found. The frequency dependent ac conductivity at different temperature indicates that the conduction process is thermally activated. The activation energy has been obtained from the Arrhenius fitting. The obtained dc conductivity showed that the system undergoes a positive temperature coefficient resistance (PTCR) to negative temperature coefficient resistance (NTCR) near 350 K. The results would help to understand deeply the relaxation process in these types of materials.

Effective Complex Permittivity And AC Conductivity Of (Bi0.5Na0.5)0.94Ba0.06 TiO3-PVDF 0-3 Composite

Ansu Kumar Roy; K. Amar Nath; K. Prasad; Ashutosh Prasad

Advanced Materials Letters, 2014, Volume 5, Issue 2, Pages 100-105
DOI: 10.5185/amlett.2013.fdm.77

The present study addresses the problem of quantitative prediction of effective complex relative permittivity and ac conductivity of (Bi0.5Na0.5)0.94Ba0.06TiO3-Polyvenylidene Fluoride (BNBT06-PVDF) 0-3 composite samples (prepared by solution cast method at an elevated temperature) having 10, 20 and 30 volume percentage of BNBT06 powder. SEM micrographs of the fractured surfaces showed that the particle distribution in the grains is not strictly homogeneous. Some areas of agglomeration of particles in the grains are also seen in the micrographs. EDAX patterns confirmed the presence of different constituent elements of the composite samples. The resulting data for room temperature real and imaginary parts of relative permittivity as well as real part of ac conductivity showed an increasing trend with increasing volume fraction of the ceramic filler. The 30 vol. % of BNBT06-PVDF composite had the highest dielectric constant of 75.3 and dielectric loss of ~6.09 i.e., loss tangent ~0.08. Among the dielectric mixing models presented, Rother-Lichtenecker model showed the best fit to the experimental data for the test composite. Similar equations for effective ac conductivity in terms of conductivity of the constituent phases of the composite were proposed in the present work to be fitted to find that none except Rother-Lichtenecker equation fitted the experimental data well. First order exponential growth type of equation applicable to all the three properties fitting the experimental data excellently is also proposed in the present work.

AC Conductivity And Battery Application Of Polyethylene Oxide/PANI/sodium Chlorate Composites

Kunteppa H; Ameena Parveen; H. G. Harish Kumar; Aashis S. Roy

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 856-861
DOI: 10.5185/amlett.2013.3444

Polymer electrolytes based on polyethylene oxide complexes with conducting polyaniline (PANI) and a salt of sodium chlorate has been prepared in different weight percentage ratios. The complexation is confirmed by FTIR spectroscopy and morphology study by employing SEM. AC conductivity measurements are carried out by using LCR Q meter at room temperature. Electrochemical cell parameters for battery applications at room temperature are also determined. The composites PP < sub>5, N3 and N4 show good conductivity which is due to ionic polarization and electrode polarization. Among all these composites N3 shows highest conductivity which is also well understood through the SEM studies. PP < sub>5 shows more conductivity than all the other composites except N3 as because PANI when mixed with PEO gives more feasibility of matrix’s for fast mobility of ions through it easily. The samples are fabricated for battery applications in configuration of Na: (PEO: PANI: NaClO4): (I2 + C + sample) and their experimental data are measured using the Wagner polarization technique.