Search results for "Electrical resistivity and conductivity"
showing 10 items of 317 documents
La 1−xCaxMnO3 semiconducting nanostructures: morphology and thermoelectric properties
2014
Semiconducting metallic oxides, especially perosvkite materials, are great candidates for thermoelectric applications due to several advantages over traditionally metallic alloys such as low production costs and high chemical stability at high temperatures. Nanostructuration can be the key to develop highly efficient thermoelectric materials. In this work, La 1−xCa x MnO3 perosvkite nanostructures with Ca as a dopant have been synthesized by the hydrothermal method to be used in thermoelectric applications at room temperature. Several heat treatments have been made in all samples, leading to a change in their morphology and thermoelectric properties. The best thermoelectric efficiency has b…
Impact of the inclusion of hydrotalcite on the morphological and electrical characteristics of an epoxy-based CNT nanocomposite
2012
The experimental results concerning the correlation between morphological and electrical characteristics of a MWCNT/epoxy based composites are presented. The impact of a nanoclay filler is investigated on the DC conductivity of a matrix loaded with different concentrations of MWCNT in order to evaluate the improvements on the dispersion of CNT inside the epoxy matrix. The dispersion is deemed to be very influencing on the electrical conductivity of the nanocomposite. A detailed morphological and structural characterization allows to interpret the electrical behaviour of the nanocomposites. © 2012 IEEE.
Structural and Electrical Transport Properties of Si doped GaN nanowires
2016
The control and assessment of doping in GaN nanostructures are crucial for the realization of GaN based nanodevices. In this study, we have investigated a series of Si-doped GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) with a typical dimension of 2–3 µm in length, and 20–200 nm in radius. In particular, high resolution energy dispersive X-ray spectroscopy (EDX) has illustrated a higher Si incorporation in NWs than that in two-dimensional (2D) layers and Si segregation at the edge of the NW with the highest doping. Moreover, direct transport measurements on single NWs have revealed a controlled doping with resistivity from 2 × 10−2 to 10−3 Ω.cm for Si doped NWs. Field effect tra…
Space charge limited current mechanism in Bi2S3 nanowires
2016
We report on the charge transport properties of individual Bi2S3 nanowires grown within the pores of anodized aluminum oxide templates. The mean pore diameter was 80 nm. Space charge limited current is the dominating conduction mechanism at temperatures below 160 K. Characteristic parameters of nanowires, such as trap concentration and trap characteristic energy, were estimated from current-voltage characteristics at several temperatures.
Mesoporous SiC with Potential Catalytic Application by Electrochemical Dissolution of Polycrystalline 3C-SiC
2018
Electrochemical dissolution of highly doped (ρ ∼ 1 mΩ·cm, n-type) polycrystalline 3C-SiC in HF/H2O and HF/H2O/ethanol solutions allowed production of porous silicon carbide (por-SiC) and soluble carbon fluorooxide nanoparticles as a byproduct. The por-SiC is a crystalline material with large pore volume, surface area close to 100 m2 g–1, and open mesoporous structure. The surface of por-SiC is covered with a thin carbon-enriched layer, bearing carboxylic acid groups. Depending on the SiC resistivity, etchant composition, and current density, three different types of por-SiC morphology, namely, a macroporous tubular, mesoporous hierarchical, and mesoporous filamentary were revealed. A qualit…
Structural study, thermal expansion and electrical conductivity of the composition NaSnZr(PO4)3
1993
Abstract The structure of the composition NaSnZr(PO4)3 and its evolution with temperature has been studied. The structure presents the space group R 3 c. The refinement of the structure shows that the Sn and Zr atoms are statistically distributed over the same crystallographic position. The unit cell expands in the c direction and contracts in the a direction, remaining the space group R 3 c at temperatures between 26 and 1000°C. The low value of the electrical conductivity at 400°C, 5.729×10−7S/cm and the low density of the pellets limited the use as electrical conductor.
Enhancement of spin Hall conductivity in W-Ta alloy
2020
Generating pure spin currents via the spin Hall effect in heavy metals has been an active topic of research in the last decade. In order to reduce the energy required to efficiently switch neighbouring ferromagnetic layers for applications, one should not only increase the charge- to-spin conversion efficiency but also decrease the longitudinal resistivity of the heavy metal. In this work, we investigate the spin Hall conductivity in W_{1-x}Ta_{x} / CoFeB / MgO (x = 0 - 0.2) using spin torque ferromagnetic resonance measurements. Alloying W with Ta leads to a factor of two change in both the damping-like effective spin Hall angle (from - 0.15 to - 0.3) and longitudinal resistivity (60 - 120…
Pre-determining the location of electromigrated gaps by nonlinear optical imaging
2014
In this paper we describe a nonlinear imaging method employed to spatially map the occurrence of constrictions occurring on an electrically-stressed gold nanowire. The approach consists at measuring the influence of a tightly focused ultrafast pulsed laser on the electronic transport in the nanowire. We found that structural defects distributed along the nanowire are efficient nonlinear optical sources of radiation and that the differential conductance is significantly decreased when the laser is incident on such electrically-induced morphological changes. This imaging technique is applied to pre-determined the location of the electrical failure before it occurs.
Low intrinsic carrier density LSMO/Alq3/AlOx/Co organic spintronic devices
2018
The understanding of spin injection and transport in organic spintronic devices is still incomplete, with some experiments showing magnetoresistance and others not detecting it. We have investigated the transport properties of a large number of tris-(8-hydroxyquinoline)aluminum-based organic spintronic devices with an electrical resistance greater than 5 MΩ that did not show magnetoresistance. Their transport properties could be described satisfactorily by known models for organic semiconductors. At high voltages (>2 V), the results followed the model of space charge limited current with a Poole-Frenkel mobility. At low voltages (∼0.1 V), that are those at which t…
Electrical conductivity properties of expanded graphite-polycarbonatediol polyurethane composites
2014
Conductive polymer composites of segmented polycarbonatediol polyurethane and expanded graphite (EG) have been synthesized with different amounts of EG conductive filler (from 0 to 50 wt%). SEM, X-ray diffraction measurements, Fourier transform infrared and Raman spectroscopies demonstrated a homogeneous dispersion of the EG filler in the matrix. The dielectric permittivity of the composites showed an insulator to conductor percolation transition with increase in EG content. Significant changes in the dielectric permittivity take place when the weight fraction of EG is in the range 20–30 wt%. Special attention has been paid to the dependence of the conductivity on frequency, temperature and…