Enhancement In DC Conductivity Research Articles

Polythiophene-g-poly(methacrylic acid) and perylene diimide appended peptide conjugates with tuneable photoluminescence, OMEIC, and photo-switching properties

Polythiophene-g-poly(methacrylic acid) conjugates with protonated perylene diimide appended dipeptide show both AIE and AIQ in fluorescence, enhancement of dc-conductivity, generate OMEIC property, and exhibit tuneable photo-switching behaviour.

Synergistic reinforcement effect of 3D graphene@multi-walled carbon nanotube hybrid nanofiller in enhancing the electrical, EMI-shielding, and mechanical properties of polyethersulfone

In this investigation, we have explored the reduced graphene oxide-multi-walled carbon nanotube (rGO-MWCNT) hybrid nanofiller as an efficient synergistic reinforcement to enhance the physical properties of polyethersulfone (PES). The rGO-MWCNT reinforced PES nanocomposite films were fabricated via a simple in-situ polymerization reaction and subsequent solution casting process. In contrast to single-component filler, the rGO-MWCNT hybrid filler exhibited better dispersion efficiency in terms of mechanical strength, electrical conductivity, and thermal stability of the PES nanocomposite, which is due to the strong synergistic effect of the hybrid filler that surpassing the performance of the individual rGO and MWCNT fillers. The maximum enhancement of dc conductivity (3.78 × 10−7 S/cm) and EMI shielding effectiveness (60 dB at a film thickness of 40 µm) are found for the nanocomposite reinforced with the hybrid filler containing rGO/MWCNT mass ratio of 3:1. The tensile strength was enhanced by 1.6-fold and Young’s modulus by 3.7-fold by the inclusion of only 2 Wt% rGO-MWCNT (3:1) hybrid filler into the PES matrix. The reinforcing efficiency of the hybrid was evaluated by comparing the experimental modulus values with theoretical data. Overall, the present PES/rGO-MWCNT nanocomposite could be potentially used as a Radar absorbing material in stealth aircraft and as high-performance material in membrane applications.

Impact of In3+ ion substitution on microstructural, magnetic and dielectric responses of nickel–cobalt spinel ferrite nanocrystals

In this article, indium ion-doped mixed nickel–cobalt ferrite nanoparticles with chemical composition Ni0.7Co0.3InxFe2−xO4 (x = 0.00, 0.05, 0.10, 0.15 and 0.30) were synthesized using soft co-precipitation method. All prepared nanoferrites showed pure cubic spinel structure without containing any impurity phases as ensured by X-ray diffraction profiles. Mean diameters of nanocrystals were found within the range of 5 nm to 13 nm as estimated from Williamson–Hall (W–H) plots. Due to large size of In3+ ions, the compressive microstrain inside the nanocrystals became tensile in nature. Both the coercive field and saturation magnetization were reduced with increasing In3+ ion concentration in nickel–cobalt ferrite nanoparticles. Overall effective anisotropy was noticed to decrease with In3+ ion doping. This is due to the diamagnetic response of indium ions and weakening of magnetic interactions. Hopping of electrons between sublattice sites was the charge conduction process for all nanoferrites as confirmed by the AC conductivity measurement. Single semi-circular arc was observed in Cole–Cole plot for all samples which also revealed that the non-conductive grain boundaries was most effective in comparison to grains in dielectric responses. Decrement in the radius of semi-circles with respect to pristine sample also indicated the enhancement in DC conductivity with indium doping.

Effect of γ- rays irradiation on structural, electrical and magnetic properties of Dy3+ substituted nanocrystalline Ni-Zn ferrites

Nanocrystalline NixZn1-xDyyFe2-yO4 (x ≤ 0 ≤ 1.0; y = 0.0, 0.1) ferrites were prepared by solution combustion method. Structural investigation was studied using XRD, FTIR, SEM and EDAX techniques. All samples were irradiated with 60Co gamma source with total exposure dose of 310 kGy. XRD patterns revealed the formation of cubic spinel structure. FTIR spectra confirm the presence of two prominent vibrational bands. DC conductivity was found to obey the Arrhenius relation with a change in slope at Curie temperature and impedes with Dy3+ ion content. ZnFe2O4 nanoparticles exhibit a weak ferrimagnetic behavior at 300 K. The saturation magnetization, remanence magnetization, coercivity, remanence ratio, magneton number and Yaffet–Kittle angle were found to decrease in Dy3+ ion substituted samples attributed to redistribution of cations amongst the sites and weakening the A-B exchange interactions. The enhancement of DC conductivity and magnetic parameters on γ-irradiation attributed to surface states pinning of domains released.

Effects of Co–Doping on Dielectric and Electrical Responses of CaCu3Ti4-x(Nb1/2In1/2)xO12 Ceramics

In this work, CaCu3Ti4-x(Nb1/2In1/2)xO12 ceramics, x = 0, 0.025, 0.05, 0.10, and 0.20, were prepared using a conventional solid state reaction method. Their crystal structure, microstructure, dielectric, and electrical properties were systematically investigated. A primary phase of CaCu3Ti4O12 ceramic was clearly observed in all samples. The average grain size of CaCu3Ti4O12 was decreased by (Nb5+, In3+) doping. The dielectric permittivity of CaCu3Ti4-x(Nb1/2In1/2)xO12 ceramics was slightly dependent on frequency as the co-dopant concentration increased, which was due to a decrease in its grain size. Their dielectric behavior can be well described by the internal barrier layer capacitor (IBLC) model based on interfacial polarization at grain boundaries. The grain boundary resistance and potential barrier height at the grain boundary of CaCu3Ti4O12 were reduced by co–doping with (Nb5+, In3+) ions, resulting in an enhancement of DC conductivity and the related dielectric loss tangent.

Experimental Investigation of Electrical Conductivity and Permittivity of SC-TiO 2 -EG Nanofluids.

The paper presents experimental studies of dielectric properties of nanofluids based on ethylene glycol and SC-TiO2 nanoparticles with average size of 15–40 nm with various mass concentrations. The dielectric permittivity both real part and imaginary part as a function of temperature and frequency were measured. Also, dependence ac conductivity on frequency, temperature, and mass concentration were investigated. Based on the curves of ac conductivity, dc conductivity was calculated, and 400 % enhancement in dc conductivity was exposed.

Charge Transport of Polyester Ether Ionomers in Unidirectional Silica Nanopores.

Dielectric relaxation spectroscopy is employed to investigate charge transport properties of two polyester ether ionomers in the bulk state and when confined in unidirectional nanoporous membranes (average pore diameter = 7.5 nm). Under nanometric confinement in nonsilanized pores, the macroscopic transport quantities (dc conductivity and characteristic frequency rate) are lower by about 1.4 decades compared to the bulk. The remarkable decrease of transport quantities in nonsilanized nanoporous membranes can be quantitatively explained by considering the temperature dependence of the interfacial layer between the ionomer and the silica membrane surfaces. On the other hand, an enhancement of dc conductivity is observed when the surfaces of the pores are treated with a nonpolar organosilane. This effect becomes more pronounced at lower temperatures and is attributed to slight changes in molecular packing density caused by the two-dimensional geometrical constraint.

Effect of nano SiO2 on properties of structural, thermal and ionic conductivity of 85.32[NaNO3]–14.68[Sr(NO3)2] mixed system

In the present study, different mole percent of SiO2 (~10–20 nm) was dispersed into 85.32[NaNO3]–14.68[Sr(NO3)2] mixed system. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) characterizations were carried out on present dispersed system. Alternate current (AC) and direct current (DC) conductivities, dielectric constant, loss, and impedance measurements have been studied in the frequency range from 1 Hz to 10 MHz and in the temperature range from 297 to 553 K. The XRD, FTIR, SEM, and DSC studies of SiO2 dispersed systems reveal the formation of amorphous phase. The frequency dependent ac conductivity follows Jonscher’s universal power law. Dimensionless frequency exponent (n) and dispersion parameter (A) are determined. The enhancement in dc conductivity is observed with the m/o of SiO2 in these electrolyte systems and attains maximum at 20.55 m/o, where from the enhancement starts falling with further increase in m/o, and this enhancement in conductivity is explained using the formation of amorphous phase of ionic salt.

Nanocomposite structures grown by inserting ionic salt RbNO3 into van der Waals gaps of III–VI compound layered semiconductors

The p-GaSe<RbNO3> and n-InSe<RbNO3> nanocomposite materials were prepared by inserting ionic salt RbNO3 from the liquid phase between layers of the layered crystals. Using this method a new technique will be available to fabricate nanocomposite structures with different morphologies. We have obtained self-organized structures that consist of a layered matrix and arrays of nanorings and nanowires formed from solid ionic salt RbNO3 nanocrystals on the atomically smooth van der Waals (0001) surfaces of layered semiconductor crystals. Atomic force microscopy, infrared spectroscopy, X-ray diffraction and impedance spectroscopy are used to characterize morphology, chemical composition, and structural and electrical properties of the grown materials. In this work, we study the role of structural properties in the electron/ionic carrier transport in the anisotropic nanocomposite structures. The enhancement in DC conductivity with respect to the pure high-resistance GaSe crystals observed for the nanocomposites is explained on the basis of the creation of nanoscale defects on the VDW surface. The maximum enhancement in DC conductivity was observed for GaSe<RbNO3> nanocomposites containing Ga2O3–RbNO3 branched nanowire networks.

Polyaniline-coated kenaf core and its effect on the mechanical and electrical properties of epoxy resin

Novel conducting kenaf core/polyaniline (KC-PANI) biofibers were successfully prepared via in situ oxidative polymerization. The newly developed conducting KC achieved enhancement in DC conductivity up to seven fold compared to the raw KC. Enhanced interaction was obtained between the acetylated KC-PANI surfaces compared to untreated KC-PANI, without significant loss in the cellulose crystallinity. The morphological analysis revealed uniform layers of PANI deposited on the surface of acetylated KC. Epoxy resin (EP) containing KC-PANI (EP/KC-PANI composites) showed that the electrical percolation of KC-PANI occurred at 20 wt.%. The tensile strength of the EP/KC-PANI composites was slightly reduced compared to that of EP/KC composites at the same loading fraction. However, the flexural test revealed that the presence of KC-PANI increased the flexural strength of the EP composites by up to 15 wt.% loading. Electron micrograph of the EP/KC-PANI composite indicated favourable adhesion between components.

Enhanced Interfacial Interaction and Electronic Properties of Novel Conducting Kenaf/Polyaniline Biofibers

Conducting kenaf/polyaniline (KF/PANI) biofibers were successfully prepared via in situ oxidative polymerization. It was demonstrated, for the first time, the possibility of imparting new electronic properties on KF by coating with acid-doped PANI. The morphological analysis revealed three different PANI morphologies on the KF, depending on the type of acid doping. Enhanced interaction was achieved between the fiber-PANI surfaces, mainly from the π − π interactions. The newly developed conducting biofibers achieved enhancement in DC conductivity up to fivefold compared to the unmodified KF. Mechanical test on the conducting biofibers revealed no significant loss in the tensile properties.

Effect of the Protonation and Chemical Doping of Poly(o-toludine) with Copper Sulfate on the Spectral and Electrical Properties of the Host Polymer

Poly(o-toluidine) (POT) and its samples doped with copper sulfate, a transition metal salt, were synthesized by a chemical oxidative polymerization technique using potassium dichromate as oxidant in aqueous hydrochloric acid medium and chemical doping with copper sulfate. The prepared polymeric samples were characterized by ultraviolet (UV)-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and DC conductivity measurement techniques. The UV-visible spectra of doped polymer displayed peaks indicating the presence of charged particles/polarons and/or formation of conducting POT. The characteristic FTIR peaks of the doped polymer provided information regarding structural changes in the backbone of POT and were consistent with the interaction of the benzenoid groups of the polymer with metal ions. X-ray diffraction patterns of powdered doped polymer showed an amorphous nature, as exhibited by most conducting polymers. The DC conductivity of doped polymer was measured by a two-probe method in the temperature range of 300–400 K; a significant enhancement in DC conductivity was observed with an increase in temperature, showing the semiconductor nature of the synthesized doped polymer.

Effects of Ta5+ doping on microstructure evolution, dielectric properties and electrical response in CaCu3Ti4O12 ceramics

Abstract The effects of Ta 5+ substitution on the microstructure, electrical response of grain boundary, and dielectric properties of CaCu 3 Ti 4 O 12 ceramics were investigated. The mean grain size decreased with increasing Ta 5+ concentration, which was ascribed to the ability of Ta 5+ doping to inhibit grain boundary mobility. This can decrease dielectric constant values. Grain boundary resistance and potential barrier height of CaCu 3 Ti 4 O 12 ceramics were reduced by doping with Ta 5+ . This results in enhancement of dc conductivity and the related loss tangent. Influence of charge compensations on microstructure and intrinsic electrical properties of grain boundaries resulting from the effects of replacing Ti 4+ with Ta 5+ are discussed. The experimental data and variation caused by the substitution of Ta 5+ can be described well by the internal barrier layer capacitor model based on space charge polarization at the grain boundaries.

DC Conductivity and Spectroscopic Characterization of Poly (o-toluidine) Doped with Binary Dopant ZrOCl&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;/AgI

Aqueous binary dopant (ZrOCl2/AgI) is used in different ratio such as 1:1, 1:2 and 2:1 (w/w) for chemical doping to enhance the conductivity of synthesized Poly (o-toluidine) (POT). The doping of Poly (o-toluidine) is carried out using tetrahydrofuran as solvent. Doped samples are characterized using various techniques such as I-V characteristics, UV-Visible spectroscopy, X-ray diffractometry (XRD), FTIR and Photoluminescence (PL) studies. A significant enhancement in DC conductivity has been observed with the introduction of binary dopant. UV-Visible study shows that optical parameters change considerably after doping. Interestingly, both direct and indirect band gaps are observed in the doped samples. XRD patterns show the semi-crystalline nature of doped Poly (o-toluidine). FTIR study shows structural modifications in functional groups with doping in POT. A Photolyminescence spectrum exhibits the emission properties of the samples.

Electrical conductivity and relaxation of Se–S–In glasses

The electrical conductivity and electrical relaxation for Se–S–In glasses have been reported in the frequency range 0.12–100 KHz and in the temperature range 303–390 K. The enhancement of dc conductivity with increasing indium content has been attributed to the increase in charge carrier mobility. The ac conductivity is found to obey the modified power law σ′ = σdc + AωS + Bω1. The electrical relaxation is represented in electric modulus formalism. The relaxation dynamic is independent of temperature and shows non-Debye nature.