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1

Role of molybdenum ions in lead zinc phosphate glass system by means of dielectric studies

Venkateswara Rao P., Naga Raju G., Syam Prasad P., Satyanarayana T., Srinivasa Rao L., Goumeidane F., Iezid M., Marltan W., Sahaya Baskaran G., Veeraiah N.

Materials Science Poland

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2018

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Vol. 36, No. 4

623--629

EN

PbO-ZnF2-P2O5 glasses doped with different mol% (0.1 to 1.0) of MoO3 have been prepared. Dielectric properties ∊′(ω), tanδ, σAC, of the synthesized samples were calculated from frequency measurements versus temperature. Space charge polarization was used to analyze the temperature and frequency dispersions of dielectric constant ∊′(ω) and dielectric loss tanδ. Quantum mechanical tunneling model was employed to explain the origin of AC conductivity. The AC conductivity exhibited an increasing trend with increasing concentration of MoO3 (up to 0.2 mol%) but the activation energy for conduction decreased. The plots of AC conductivity revealed that the relaxation dynamics depends on MoO3 dopant concentration.

2

Polyaniline: tin oxide polymeric nanocomposite films. An electrical and dielectric study

Arora R., Chand S., Sharma P.

Materials Science Poland

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2018

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Vol. 36, No. 4

711-716

EN

A conducting nanocomposite film of 60 nm nano-SnO2-polyaniline (PANI) and polyvinyl alcohol (PVA) has been synthesized and analyzed in terms of AC conductivity and dielectric behavior. The conducting polymer nanocomposite of PANI/60 nm (SnO2) and polyvinyl alcohol (PVA) has been prepared via in situ polymerization technique. The morphology of the nanocomposite film has been studied by SEM. The film has been characterized in terms of DC conductivity. The dielectric behavior and AC conductivity of the nanocomposite film have been investigated in the frequency range of 2 Hz to 90 KHz. The film has high dielectric constant which may be correlated with polarization. It has been observed that both dielectric loss and dielectric constant decrease with an increase in frequency.

3

AC low frequency conductivity in PZT PFS ferroelectric ceramics

Osak A.

Technical Transactions

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2017

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Vol. 1(114)

173--185

EN

Low frequency AC conductivity has been studied in ferroelectric ceramics PZT + PFS (Pb[(Fe1/3Sb2/3)xTiyZrz]O3 with x = 0.1 and y = 0.43, 0.44, 0.47) using Fourier transformation of charging and discharging currents. The results are interpreted in terms of fractal structure of the randomly generated clusters formed by sequentially correlated hopping paths of charge carriers.

PL

W artykule przedstawiono przewodnictwo zmiennoprądowe ceramiki ferroelektrycznej PZT + PFS (Pb[(Fe1/3Sb2/3)xTiyZrz]O3, gdzie x = 0.1 i y = 0,43, 0,44, 0,47) w zakresie ultra niskich częstotliwości obliczone na podstawie analizy Fouriera prądów polaryzacji i depolaryzacji dielektrycznej. Wyniki zostały zinterpretowane na podstawie fraktalnej struktury klasterów generowanych przez stochastyczny sekwencyjny hopping nośników ładunku.

4

Structural, optical and electrical characterization of CBD synthesized CdO thin films: influence of deposition time

Das M.R., Mukherjee A., Mitra P.

Materials Science Poland

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2017

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Vol. 35, No. 3

470--478

EN

Cadmium oxide (CdO) thin films were grown on glass substrates by chemical bath deposition (CBD) method for different deposition times using cadmium acetate as cationic precursor. The structural and optical characterization was carried out using XRD, TEM, and UV-Vis spectrophotometer measurements. Structural analyses with XRD confirmed cubic structure of the CdO. Average particle size estimated from Rietveld refinement method of XRD pattern corresponded well with TEM measurement. The optical band gap varied between 2.35 eV to 2.48 eV with deposition time and an increase in optical band gap with decreasing film thickness was observed. The AC electrical conduction behavior of the CdO film was investigated as a function of temperature as well as frequency. The conductivity measurements indicated localized conduction and hopping of carriers between localized states. The value of real part of dielectric constant was found to decrease with frequency and increase with temperature. The Nyquist plots at different temperatures showed the existence of both grains and grain boundaries contributing to conduction mechanism.

5

Structural, optical and dielectric studies of lithium sulphate monohydrate single crystals

Najar F. A., Vakil G. B., Want B.

Materials Science Poland

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2017

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Vol. 35, No. 1

18--31

EN

Optical, dielectric, and thermal properties of lithium sulphate monohydrate crystals grown by slow evaporation method have been studied. The crystal structure was resolved by direct methods using single crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0174. Plasma energy, Penn gap, Fermi energy and electronic polarizability of the grown crystal were calculated from single crystal XRD data. The electronic polarizability of lithium sulfate monohydrate was also calculated and compared with the theoretical data using Clausius-Mossotti equation. Optical band gap calculated from optical data for the grown crystal is 4.49 eV. Fourier Transform Infrared Spectroscopy study confirmed the presence of water in the crystal structure. The AC conductivity, dielectric constant and dielectric loss of the grown crystal were systemically investigated, showing a peak at about 130 °C which could be attributed to the water molecules in the crystal structure. The anomalous dielectric properties shown by the crystal have been correlated with its thermal behavior. The title crystal obeys Jonscher’s power law relation; σ(ω) = σο+ Aωs, with temperature dependent exponent s < 1. The activation energy calculated for the material is 0.24 eV and suggests protonic conduction by hopping mechanism in addition to cationic conduction by lithium ions. The micro-indentation study was also carried out which revealed that the crystal belongs to a category of soft materials.

6

Structural, dielectric and AC conductivity studies on 0.8Ba0.2(Bi0.5K0.5)Ti1-xZrxO3 lead free ceramic system

Ramesh M. N. V., Ramesh K. V.

Materials Science Poland

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2016

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Vol. 34, No. 3

669--675

EN

Zr substituted 0.8BaTiO30.2 Bi0,5 K0,5 TiO3 lead free ceramic materials with a composition 0.8Ba0.2(Bi0,5 K0,51-xZrxO3 (0.01 ≤x ≤0.06) were prepared by conventional solid state reaction method followed by high energy ball milling. The X-ray diffraction studies confirmed the tetragonal structure of the material at room temperature. Density was decreasing with the substitution of Zr. Microstructure studies were done by using scanning electron microscope. Temperature and frequency dependent dielectric studies were carried out and showed that the dielectric constant, dielectric loss and Curie temperature were decreasing with the substitution of Zr. Relaxor behavior was observed in all the Zr substituted samples. Degree of diffuseness was calculated from the modified Curie-Weiss law and it was found to increase with the substitution of Zr. Frequency and temperature dependent AC conductivity was calculated and it was found to obey Jonscher’s power law. Substitution of Zr decreased the conductivity of the material. Activation energy was calculated and it was decreasing with an increase in Zr substitution.

7

Analysis of X-ray structure, dielectric properties and AC conductivity of (4E)-2-amino-3-cyanobenzo[b]oxocin-6-one

Ali H. A. M., Ibrahim M. A.

Materials Science Poland

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2016

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Vol. 34, No. 2

386--392

EN

The crystal structure of (4E)-2-amino-3-cyanobenzo[b]oxocin-6-one, denoted as 4(E)-ACBO, was analyzed using X-ray diffraction technique. The dielectric and AC electrical conductivity measurements of the bulk 4(E)-ACBO in the form of pellet were studied in the range of frequency 42 Hz to 5 MHz and the temperature range of 303 K to 373 K. The temperature and frequency dependence of dielectric constant (ε1), dielectric loss (ε2) and AC electrical conductivity (δ εAC) were investigated. The relaxation time (τ) for electrons to hop over a barrier of height WH was calculated at different temperatures. The AC activation energy was determined from the temperature dependence of δ AC at different frequencies.

8

Frequency and temperature dependence of dielectric and electric properties of Ba2-xSm4+2x/3Ti8O24 with structural analysis

Narang S. B., Kaur D., Pubby K.

Materials Science Poland

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2015

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Vol. 33, No. 2

268--277

EN

Dielectric ceramics samples of barium titanium oxide doped with samarium, having a complex structural formula of Ba2-xSm4+2x/3Ti8O24 (referred to as BST), were fabricated by a high temperature solid-state reaction technique with varying x (0.0, 0.2, 0.4, 0.6). X-ray diffraction technique was used to check the formation of particular phases. Scanning electron microscope technique was used to study the surface morphology of the samples. The samples were studied in a temperature range of 298 K to 623 K and frequency range of 10 KHz to 1 MHz. The dielectric constant (εr), loss tangent (tanδ), and AC conductivity (σAC) were measured on sintered disks of BST samples. The DC resistivity of different compositions was measured at room temperature. Detailed studies of dielectric and electrical properties showed that these properties are strongly dependent on composition, frequency and temperature. The compounds showed stable behavior in lower temperature range (up to 523 K), therefore, they can be used in practical applications in this temperature range.