scholarly journals Synthesis of polyaniline in presence of low magnetic field, its structure and electrical properties

2008 ◽  
Vol 2 (2) ◽  
pp. 105-109
Author(s):  
Nafdey Renuka ◽  
◽  
Kelkar Deepali ◽  

Polyaniline is synthesized chemically under the influence of low magnetic field of intensity 1KGauss. The effect of magnetic field during the synthesis process causes enhancement of electrical conductivity by two orders of magnitude. This increased electrical conductivity depends on the polymer chain ordering, as well as structure and morphology of the reported polymer.

2010 ◽  
Vol 160 (7-8) ◽  
pp. 728-731 ◽  
Author(s):  
Jae-Kook Park ◽  
O-Pil Kwon ◽  
Eun-Young Choi ◽  
Chan-Keun Jung ◽  
Suck-Hyun Lee

1994 ◽  
Vol 59 (11) ◽  
pp. 2436-2446 ◽  
Author(s):  
Mária Reháková ◽  
Anna Sopková ◽  
Vladimír Šály

The presence of iodine and iodide ions in tetracyanonickelates inclusion compounds with the general formula Ni(B)mNi(CN)4 . n H2O (B = NH3 or ethylenediamine) changes the properties of these compounds. High frequency conductance measurements in the range of 10 - 105 Hz show that the products with ethylenediamine ligands have a higher electrical conductivity than those with NH3 ligands. The differences in the electrical properties between the compounds studied are mainly caused by chemical composition, structure and morphology.


1989 ◽  
Vol 169 ◽  
Author(s):  
Yonhua Tzeng ◽  
Mitchell A. Belser

AbstractThe effects of low magnetic field (0–40 Gauss) on electrical properties of gold-YBCO contacts are investigated. The contact resistance increases significantly with applied magnetic fields. For high magnetic field or when high current is flowing through the contact, the contact resistance decays after removing the magnetic field to a finite value greater than that is measured before the contact is exposed to the magnetic field and stays there for long time as long as the sample is kept below the superconductivity critical temperature.


Author(s):  
Shuai Dong ◽  
Shiwei Chen ◽  
Bin Li ◽  
Xiaojie Wang

Graphene nanoplate (GNP) is a two-dimensional plate-like carbon material with high aspect ratio and excellent electrical conductivity. It is one of the most commonly used fillers for conductive polymer composites (CPCs), which have potential applications in flexible electrodes and sensors. The electrical properties of the CPCs particularly depend on the microstructure of GNP networks. The electrical conductivity of the CPCs leaps in several magnitude levels when the graphene concentration reaches a critical value, which is defined as the percolation threshold. For ordinary isotropic CPCs, the percolation threshold is relatively high, which leads to inferior performance with poor mechanical and electrical properties. Aligning the graphene plates is an effective method to reduce the percolation threshold of the CPCs. Carbonyl iron particles (CIPs) are easily aligned to form chain-like structures when a magnetic field is applied. In this work, CIPs and GNPs are mixed with polydimethylsiloxane (PDMS), and the hybrid is cured under a magnetic field of 0.5 T. The alignment of CIPs induces the GNPs in the PDMS to orientate in a certain direction under the applied magnetic field generating anisotropic structures. Both isotropic and anisotropic structured GNPs/PDMS composites are prepared with various GNP concentrations. The microstructure and electrical conductivity of the GNPs/PDMS composites are investigated by experimental methods. It is found that anisotropic graphene networks are formed and the percolation threshold of the anisotropic composites is 0.15 vol%, compared to that of the isotropic composites which is 0.85 vol%. The alignment of GNPs significantly reduces the percolation threshold. Furthermore, a plate lattice model is proposed to reveal the effect of the alignment of GNPs on the formation of conductive networks. With the increase of the alignment degree of GNPs, the percolation threshold decreases significantly, which is consistent with the experimental results.


Author(s):  
K.V. Kirilenko

In the context of rising energy costs and the need to use new energy sources, works aimed at raising the surface temperature of heat radiators with reduced energy consumption are of particular importance, and it is especially important if these processes are also accompanied by the effects of self-stabilization. Bulk materials do not possess these properties. However, materials whose dielectric matrix is also an active element can provide up to 10 - 30% of the thermal energy that will be released in the material, thereby increasing the surface temperature and without increasing energy consumption. Therefore, the study of composite materials with different matrices is relevant. This article the influence of the matrix material on the electrical properties of composite materials was examined. It was established that the microstructure morphology of resistive materials changes significantly depending on the matrix type. In composites based on matrix AlN, for the entire range of concentrations HfC, conducting cluster is formed with a metallic conductivity. For composite systems Al2O3-HfC and Si3N4-HfC thermoactivated hopping conduction between nearest neighboring states observed. Thus, for materials based on Si3N4 matrix at temperatures up to 300°C observed reduction of charge carriers concentration with increasing temperature. The approximation of the temperature dependence of the electrical conductivity was carried out on the basis of the following possible variants of the nature of the electrical conductivity, namely: jump conductivity (nonlocalized states, localized states in the tails of conduction and valence bands, localized states near the Fermi level), tunneling. It can be assumed that the formation of conductive clusters occurred under the influence of two factors: magnetic field and mechanical loading. When using the AlN matrix, the influence of the magnetic field on the structure formation is smallest. This conclusion can be drawn from the fact that the formed conductive clusters have the appearance of a linear chain structure.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7484
Author(s):  
Nursyafiqah Zaini ◽  
Norzilawati Mohamad ◽  
Saiful Amri Mazlan ◽  
Siti Aishah Abdul Aziz ◽  
Seung-Bok Choi ◽  
...  

Common sensors in many applications are in the form of rigid devices that can react according to external stimuli. However, a magnetorheological plastomer (MRP) can offer a new type of sensing capability, as it is flexible in shape, soft, and responsive to an external magnetic field. In this study, graphite (Gr) particles are introduced into an MRP as an additive, to investigate the advantages of its electrical properties in MRPs, such as conductivity, which is absolutely required in a potential sensor. As a first step to achieve this, MRP samples containing carbonyl iron particles (CIPs) and various amounts of of Gr, from 0 to 10 wt.%, are prepared, and their magnetic-field-dependent electrical properties are experimentally evaluated. After the morphological aspect of Gr–MRP is characterized using environmental scanning electron microscopy (ESEM), the magnetic properties of MRP and Gr–MRP are evaluated via a vibrating sample magnetometer (VSM). The resistivities of the Gr–MRP samples are then tested under various applied magnetic flux densities, showing that the resistivity of Gr–MRP decreases with increasing of Gr content up to 10 wt.%. In addition, the electrical conductivity is tested using a test rig, showing that the conductivity increases as the amount of Gr additive increases, up to 10 wt.%. The conductivity of 10 wt.% Gr–MRP is found to be highest, at 178.06% higher than the Gr–MRP with 6 wt.%, for a magnetic flux density of 400 mT. It is observed that with the addition of Gr, the conductivity properties are improved with increases in the magnetic flux density, which could contribute to the potential usefulness of these materials as sensing detection devices.


2011 ◽  
Vol 189-193 ◽  
pp. 1340-1343 ◽  
Author(s):  
Yu Zhang ◽  
Chuan Guo Ma

Aligned carbon nanotubes(CNTs)/epoxy resin(EP) composites were prepared under a low magnetic field (B<500mT) induction. The effect of different magnetic fields on the electrical and dielectrical properties of composites was investigated. The results show that the CNTs are aligned with rod-like aggregations instead of single CNTs when the magnetic field direction is vertical to the casting direction of samples, then electric conductivity, permittivity, dielectric loss of the composite are improved. And a larger magnetic field intensity and a bigger mould capacity can help the effect of magnetic field induction. However the CNTs are seriously aggregated and the electrical properties of composites change worse when the magnetic field direction is parallel to the casting direction of samples.


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