Electrical transport in lead-free Na0.5Bi0.5TiO3 ceramics

AbstractLead-free Na0.5Bi0.5TiO3 (NBT) ceramics were prepared via a conventional oxide-mixed sintering route and their electrical transport properties were investigated. Direct current (DC, σDC) and alternating current (AC, σAC) electrical conductivity values, polarization current (first measurements) and depolarization current, current–voltage (I–U) characteristics (first measurements), and the Seebeck coefficient (α) were determined under various conditions. The mechanism of depolarization and the electrical conductivity phenomena observed for the investigated samples were found to be typical. For low voltages, the I–U characteristics were in good agreement with Ohm’s law; for higher voltages, the observed dependences were I–U2, I–U4, and then I–U6. The low-frequency σAC followed the formula σAC–ωs (ω is the angular frequency and s is the frequency exponent). The exponent s was equal to 0.18–0.77 and 0.73–0.99 in the low- and high-frequency regions, respectively, and decreased with temperature increasing. It was shown that conduction mechanisms involved the hopping of charge carriers at low temperatures, small polarons at intermediate temperatures, and oxygen vacancies at high temperatures. Based on AC conductivity data, the density of states at the Fermi-level, and the minimum hopping length were estimated. Electrical conduction was found to undergo p–n–p transitions with increasing temperature. These transitions occurred at depolarization temperature Td, 280 ℃, and temperature of the maximum of electric permittivity Tm is as typical of NBT materials.

Download Full-text

Thermal and Electrical Transport Properties of o-Substituted Polyanilines Encapsulated with CuO Nanoparticles

Asian Journal of Chemistry ◽

10.14233/ajchem.2019.22134 ◽

2019 ◽

Vol 31 (10) ◽

pp. 2261-2268

Author(s):

R. Suganthi ◽

S. Jhancy Mary

Keyword(s):

Electrical Conductivity ◽

Electrical Transport ◽

Oxidative Polymerization ◽

Low Frequency ◽

Frequency Dispersion ◽

Decomposition Temperature ◽

Electrical Transport Properties ◽

Frequency Independent ◽

The Stability ◽

Independent Behavior

Fabrication of substituted polyaniline nanocomposites with CuO results in hybrid materials with enhanced synergistic properties. Hence poly(2-chloroaniline)-composite-CuO, poly(2-chloroaniline)-composite-CuO/SDS, poly(2-methoxyaniline)-composite-CuO/SDS and poly(2-methylaniline)-composite-CuO/SDS nanocomposites were prepared chemically by in situ oxidative polymerization method. Characterization by a number of techniques such as FTIR, NMR and UV-visible spectroscopic methods, XRD and TEM are presented. The substituted polymers exhibited an appreciable interaction with the CuO (5 wt.%) nano fillers. Integral Procedural Decomposition Temperature (IPDT) and Oxidative Index(OI) calculations were done to establish the stability to heat. Thermal stability of the materials follows the trend p2ClAni-CuO-SDS > p2ClAni-CuO> p2MeAni-CuO-SDS> p2OMeAni-CuO-SDS. The electrical conductivities of poly(2-chloroaniline)-composite-CuO and poly(2-chloroaniline)-composite-CuO/SDS measured are 1.46 × 10-7 and 1.59 × 10-7 S cm-1, respectively and the presence of anionic surfactant does not change the electrical conductivity behaviour. The poly(2-methoxyaniline)/CuO-SDS and poly(2-methylaniline)/CuO-SDS exhibit an electrical conductivity of 1.68 × 10-6 and 1.24 × 10-6 S cm-1 respectively. The dielectric constant decreased with increase in frequency in the low frequency region due to electrical relaxation process. At low frequency there was a strong frequency dispersion of permittivity and above 2.5 Hz a frequency independent behavior was noted

Download Full-text

Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Crystals ◽

10.3390/cryst11070746 ◽

2021 ◽

Vol 11 (7) ◽

pp. 746

Author(s):

Meiling Hong ◽

Lidong Dai ◽

Haiying Hu ◽

Xinyu Zhang

Keyword(s):

Phase Transition ◽

Electrical Conductivity ◽

High Pressure ◽

Phase Transformation ◽

Transport Properties ◽

Electrical Transport ◽

Structural Phase ◽

Structure Evolution ◽

Systematic Research ◽

Electrical Transport Properties

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

Download Full-text

Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing

Polymers ◽

10.3390/polym14020336 ◽

2022 ◽

Vol 14 (2) ◽

pp. 336

Author(s):

Yu Shang ◽

Qiang Liu ◽

Chen Mao ◽

Sen Wang ◽

Fan Wang ◽

...

Keyword(s):

Electrical Conductivity ◽

Moisture Content ◽

Charge Carriers ◽

Dynamics Simulation ◽

Water Molecules ◽

Stable Operation ◽

Polarization Current ◽

Depolarization Current ◽

Moisture Condition ◽

Dc Voltage

Cellulose insulation polymer material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

Download Full-text

Structure-Electrical Transport Property Relationship of Anisotropic iPP/CNT Films

MRS Proceedings ◽

10.1557/opl.2013.445 ◽

2013 ◽

Vol 1499 ◽

Cited By ~ 1

Author(s):

Parvathalu Kalakonda ◽

Michael Daly ◽

Kaikai Xu ◽

Yaniel Cabrera ◽

Robert Judith ◽

...

Keyword(s):

Electrical Conductivity ◽

Electrical Transport ◽

Preparation Method ◽

Weight Percent ◽

Electrical Transport Properties ◽

Oriented Polymer ◽

Nano Composite ◽

Nano Structure ◽

Relationship Of ◽

Fine Tune

ABSTRACTThe internal micro/nano-structure of anisotropically oriented polymer/CNTs composites determines their macroscopic properties. However, the connections between the two are not fully understood. The varying of CNT concentration, preparation method, and a thermodynamic parameter (e.g. temperature) can all play interconnected role. In this work, the macroscopic electrical conductivity was measured perpendicular to the film thickness of an insulating polymer (isotactic PolyPropylene, iPP) and a nano-composite of iPP with 5 weight percent of CNT. The thin films studied were sheared (anisotropically nano-structured) and non-sheared (with random internal structure). In general the effect of melt shearing induces anisotropy on the electrical transport properties of the iPP/CNT films in directions parallel and perpendicular to the direction of orientation. Our results show that for the pure iPP, resistivity slightly increases with shear at higher temperatures. When CNTs are introduced, there is a large difference between the resistivity of the sheared and non-sheared nanocomposite. The sheared PNCs when the CNTs are aligned parallel to each other, have higher resistivity, which is possibly due to the higher concentration at which the percolation threshold occurs in this arrangement. The resistivity decreases overall, as the temperature increases from 0 to 50 °C. These results show that CNTs can be used to control and fine tune the desired macroscopic physical properties of nanocomposites, by concentration and orientation, such as electrical conductivity, for applications where such properties are necessary.

Download Full-text

Magnetic and Electrical Transport Properties of Vanadium Telluride

Zeitschrift für Naturforschung A ◽

10.1515/zna-1980-0708 ◽

1980 ◽

Vol 35 (7) ◽

pp. 701-703 ◽

Cited By ~ 2

Author(s):

C. Prasad ◽

R. A. Singh

Keyword(s):

Electrical Conductivity ◽

Dielectric Constant ◽

Magnetic Susceptibility ◽

Electrical Transport ◽

Powdered Sample ◽

Neel Temperature ◽

Electrical Transport Properties ◽

Néel Temperature ◽

Paramagnetic Curie Temperature ◽

Temperature Range

Measurements of the magnetic susceptibility of a powdered sample of VTe in the temperature range 90 - 700 K, and of the a.c. electrical conductivity (σ), thermoelectric power (θ) and dielectric constant (ε′) of pressed pellets of the compound in the temperature range 300 -1100 K are reported. The compound is found to be antiferromagnetic with Neel temperature 420 ± 5 K. The effective paramagnetic moment and paramagnetic Curie temperature are found to be 1.6 μB and - 250 K, respectively. The dependence of σ, θ and ε′ on temperature shows no anomaly at the Neel temperature and is indicative of the metallic nature of the compound.

Download Full-text

Computational Analysis of Strain Effects on Electrical Transport Properties of Crystalline Nanocomposite Thin Films

Volume 11: Nano and Micro Materials, Devices and Systems; Microsystems Integration ◽

10.1115/imece2011-64641 ◽

2011 ◽

Author(s):

Hua Li ◽

Gang Li

Keyword(s):

Thin Films ◽

Electrical Conductivity ◽

Band Structure ◽

Transport Properties ◽

Electrical Transport ◽

Electronic Band Structure ◽

Electrical Transport Properties ◽

Electronic Band ◽

Strain Effects ◽

Nanocomposite Thin Films

In this work, we model the strain effects on the electrical transport properties of Si/Ge nanocomposite thin films. We utilize a two-band k·p theory to calculate the variation of the electronic band structure as a function of externally applied strains. By using the modified electronic band structure, electrical conductivity of the Si/Ge nanocomposites is calculated through a self-consistent electron transport analysis, where a nonequilibrium Green’s function (NEGF) is coupled with the Poisson equation. The results show that both the tensile uniaxial and biaxial strains increase the electrical conductivity of Si/Ge nanocomposite. The effects are more evident in the biaxial strain cases.

Download Full-text

Thermoelectric properties of polycrystalline Bi2Se3−x by powder compaction sintering

Modern Physics Letters B ◽

10.1142/s0217984920502061 ◽

2020 ◽

Vol 34 (18) ◽

pp. 2050206

Author(s):

Ying Zhou ◽

Zhenhua Ge ◽

Jun Guo ◽

Jing Feng

Keyword(s):

Electrical Conductivity ◽

Seebeck Coefficient ◽

Carrier Concentration ◽

Thermoelectric Properties ◽

Thermoelectric Materials ◽

Electrical Transport ◽

Bulk Material ◽

Powder Compaction ◽

Electrical Transport Properties ◽

X Ray

[Formula: see text] is a [Formula: see text] compound (where Pn = Bi and Sb, Ch = Te, Se, and S), which has attracted increasing attention as a candidate for use in thermoelectric applications. Previous studies demonstrated the advantage of [Formula: see text] thermoelectric materials, despite an inferior thermoelectric performance. Herein, a series of [Formula: see text] ([Formula: see text], 0.10, 0.15, 0.20, and 0.25) thermoelectric materials were prepared by powder compaction sintering. The effects of phase structures and microstructure of the [Formula: see text] bulk material were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The thermoelectric properties, including Seebeck coefficient, electrical conductivity, and thermal conductivity, were measured systematically. The results show that carrier concentration increased with decreasing Se content, which in turn affected the electrical transport properties. Low Se contents gave larger power factor (PF) values than the pristine [Formula: see text] sample, the maximum PF value being [Formula: see text] at 320 K for [Formula: see text]. The variation in PF was attributed to the variations in electrical conductivity [Formula: see text] and Seebeck coefficient [Formula: see text] upon optimizing Se content. The [Formula: see text] samples showed an enhanced thermoelectric figure of merit (ZT) with increasing measurement temperature, due to the increased [Formula: see text] value, [Formula: see text], and decreased [Formula: see text]. The [Formula: see text] sample exhibited the highest ZT (0.28) at 575 K, while [Formula: see text] exhibited the lowest ZT (0.14) at 325 K. This indicated that tuning Se content was an effective way to enhance carrier concentration.

Download Full-text

Rapid Nanomanufacturing of Metallic Break Junctions Using Focused Ion Beam Scratching and Electromigration

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4001664 ◽

2010 ◽

Vol 132 (3) ◽

Cited By ~ 16

Author(s):

Waseem Asghar ◽

Priyanka P. Ramachandran ◽

Adegbenro Adewumi ◽

Mohammud R. Noor ◽

Samir M. Iqbal

Keyword(s):

Molecular Electronics ◽

Electrical Transport ◽

Focused Ion Beam ◽

Ion Beam ◽

High Yield ◽

Electrical Transport Properties ◽

Metal Line ◽

Break Junctions ◽

Current Voltage ◽

Before And After

Break junctions provide a direct way to interrogate electrical transport properties of molecules, in pursuit of molecular electronics devices. A number of approaches are used for the fabrication of break junctions, including optical/e-beam lithography, electromigration, mechanical control of suspended conductive electrodes/strips, and electrochemical deposition of conductive material and nanowires. All approaches either require serial and slow e-beam writing of nanoscale gaps or suffer from low-yield of nanogap electrode devices. Here, we report the use of focused ion beam (FIB) to “scratch” and remove a thin layer of gold from 3 μm wide lines. The scratch results in thinning of the metal line and subsequent current-driven electromigration results into nanogaps at precise locations with high yield of devices. Combining FIB scratching with electromigration provides an elegant approach of creating nanoscale break junctions at an exact location and with a very narrow distribution of the nanogap sizes. Current-voltage measurements are done using a probe station before and after FIB scratch, and after the breaks were formed. Most of the gaps fall within 200–300 nm range and show negligible conductivity. The approach provides a novel, rapid, and high-throughput manufacturing approach of break junction fabrication that can be used for molecular sensing.

Download Full-text

Tungsten Disulfide Nanodispersions for Inkjet Printing and Semiconducting Devices

MRS Advances ◽

10.1557/adv.2017.338 ◽

2017 ◽

Vol 2 (60) ◽

pp. 3691-3696 ◽

Cited By ~ 2

Author(s):

Jay A. Desai ◽

Nirmal Adhikari ◽

Anupama B. Kaul

Keyword(s):

Electrical Conductivity ◽

Surface Morphology ◽

Inkjet Printing ◽

Electrical Transport ◽

Large Scale ◽

High Electrical Conductivity ◽

Absorbance Spectrum ◽

Electrical Transport Properties ◽

Optical Absorbance ◽

Device Applications

ABSTRACTIn this work, we demonstrate optical and electrical transport properties of chemically exfoliated WS2 in cyclohexanone/ terpineol solvent using different sonication times. High electrical conductivity of WS2 nanodispersions was observed when appropriate amount of voltage was applied indicating their semi-conductive behavior. Surface morphology of WS2 nanodispersions sonicated at different times were studied using optical microscopy. Optical bandgap of WS2 nanodispersions were determined from optical absorbance spectrum. Inkjet printing was used to demonstrate uniform distribution of WS2 nanosheets and their precise and large scale printability. These dispersions indicate the potential of WS2 in various optoelectronic and semiconducting device applications.

Download Full-text