Mechanical and dielectric behavior of LDPE/Bi-1212 films

The present study deals with the improvement of the mechanical and dielectric properties of low-density polyethylene (LDPE) by incorporating BiSr2CaCu2O6.5(coded as Bi-1212) ceramic powder. In this context, LDPE/Bi-1212 films with different ceramic weight contents were prepared by hot press technique. The ceramic reinforcing material was produced by a solid-state reaction technique. While the surface morphologies of the films were determined using a scanning electron microscope (SEM), the chemical structure analyses of the samples were performed by Fourier transform infrared (FTIR) spectroscopy. The mechanical performances of the specimens were evaluated by determining the tensile strength, Young’s modulus, percentage strain at break, and energy at the break values obtained by stress-strain curves. The real and imaginary components of the complex permittivity, as well as the alternating current (ac) conductivities of the samples, were measured within in the frequency interval of 1 Hz-1 MHz between 293 K and 353 K. As a result of tensile properties analyses as well as the investigations of ac electrical parameters, it was revealed that the LDPE/1.0 wt.-% Bi-1212 composite has a promising potential in electronic applications due to its improved mechanical durability, charge storage ability and conductivity.

A renormalisation group equation for transport coefficients in (2 + 1)-dimensions derived from the AdS/CMT correspondence

Within the framework of the AdS/CMT correspondence asymptotically anti-de Sitter black holes in four space-time dimensions can be used to analyse transport properties in two space dimensions. A non-linear renormalisation group equation for the conductivity in two dimensions is derived in this model and, as an example of its application, both the Ohmic and Hall DC and AC conductivities are studied in the presence of a magnetic field, using a bulk dyonic solution of the Einstein-Maxwell equations in asymptotically AdS4 space-time. The $$ \mathcal{Q} $$ Q -factor of the cyclotron resonance is shown to decrease as the temperature is increased and increase as the charge density is increased in a fixed magnetic field. Likewise the dissipative Ohmic conductivity at resonance increases as the temperature is decreased and as the charge density is increased. The analysis also involves a discussion of the piezoelectric effect in the context of the AdS/CMT framework.

Development of Bright Fluorescent Poly(1-vinyl-2-pyrrolidone-co-acrylonitrile) and Its Polysalts with HCl and HNO3: Materials for Solid State Electrical Applications

Herein, we have reported the synthesis, characterization, and ionic conductivity analysis of fluorescent poly(1-vinyl-2-pyrrolidone-co-acrylonitrile) and its salts with 10% HCl and HNO3 in solid state. The synthesized polymers and their polysalts were characterized using Fourier-transformed infrared spectroscopy, UV-visible, Cyclic Voltammetry, Thermogravimetric analysis, Differential Scanning Calorimetric, X-ray diffraction, and spectrofluorometric techniques. The AC conductivities were measured in the frequency ranging from 42 Hz to 1 MHz and temperature from 30°C to 70°C in solid state. Ionic conductivities of the salts of the copolymer with hydrochloric acid and nitric acid were found to be 2.145×10−5 and 2.349×10−5 S cm −1, respectively, which are nearly 1000 times more than that of poly(1-vinyl-2-pyrrolidone-co-acrylonitrile). The activation energies for the copolymer and the polyelectrolytes were found to be 0.454, 0.6288, and 0.659 eV, respectively. The transport number of the copolymers was found to be 0.0278, and that of the polysalts was found to be 0.7596 and 0.7424, respectively. The copolymer showed distinct fluorescent when irradiated with UV light and can be used as acid vapor sensor in solid state.

Conduction in Polyaniline-Emeraldine Salt/Bentonite Composites Using Impedance Spectroscopy

In this study, different mass concentrations of Polyaniline-emeraldine salt (PAni-ES) was mixed with bentonite clay. XRD analysis showed the incorporation of PAni-ES in bentonite. The AC conductivity was calculated from Impedance measurements. The conductivities increased with increasing concentration of PAni-ES. The AC conductivities follow a transition from frequency-independent to frequency-dependent at a critical frequency, ωc. Above ωc, the conductivity follows a universal power law behavior as described for disordered materials. Using jump relaxation model, the conductivity is governed by translational ion hopping in the low-frequency region, and well-localized ion hopping in the high-frequency region.

Decomposition of the Methylene Blue Dye Using Layered Manganese Oxide Materials Synthesized by Solid State Reactions

The modulation in the synthesis parameters of layered manganese oxides allowed us to produce materials with different AC conductivities. These conductivities were correlated with the catalytic performance of the materials in the decomposition of methylene blue, as a model of electron transfer reactions. The manganese oxides were prepared by thermal reduction of KMnO4 at 400°C and 800°C where one sample was heated at 1°C/min and the other was heated at 10°C/min. The materials were characterized by atomic absorption, average oxidation states of manganese, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The results indicate that, by increasing the synthesis temperature, both the lamellar arrangement and the crystal size increased, while the Mn4+ amount in the material decreased. Furthermore, it was observed that as the conductivity increases for the materials, the catalytic performance also increases. Therefore, a direct correlation between the conductivity and catalytic performance can be established. For example, the layered manganese oxides material synthesized at 400°C, using a heating rate of 10°C/min, showed the highest AC conductivity and had the best performance in the degradation of methylene blue. Finally, we propose a general mechanism for understanding how manganese oxides behave as catalysts that produce oxidizing species from H2O2 which degrades methylene blue. Our proposed mechanism takes into consideration the state of aggregation of the catalyst, the availability of Mn4+, and the electrical conductivity.

Universal linear and nonlinear electrodynamics of a Dirac fluid

A general relation is derived between the linear and second-order nonlinear ac conductivities of an electron system in the hydrodynamic regime of frequencies below the interparticle scattering rate. The magnitude and tensorial structure of the hydrodynamic nonlinear conductivity are shown to differ from their counterparts in the more familiar kinetic regime of higher frequencies. Due to universality of the hydrodynamic equations, the obtained formulas are valid for systems with an arbitrary Dirac-like dispersion, ranging from solid-state electron gases to free-space plasmas, either massive or massless, at any temperature, chemical potential, or space dimension. Predictions for photon drag and second-harmonic generation in graphene are presented as one application of this theory.

Temperature dependence of electrical conductivity and dielectric properties in Li–Mn ferrite

Manganese substituted lithium–ferrite with the general formula Li0.5–0.5xMnxFe2.5–0.5xO4 (where x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) were synthesized by the standard ceramic technique. The variation of DC and AC conductivities has been reported as a function of temperature from room temperature (293 K) up to 970 K in static air. AC measurements were carried out over a wide range of frequencies from 100 Hz up to 1 MHz. The variation ln σ at room temperature with composition indicates that the conductivity initially increases up to 0.5 and then decreases with further addition in Mn content. The activation energy of the conduction mechanism decreases from 0.68 to 0.34 eV. The electrical conductivity in the present ferrite is explained on the basis of the hopping mechanism. Dielectric properties, such as dielectric loss tangent, tanδ, and dielectric constant, ε′, have been measured. The dielectric behavior is explained by using the mechanism of the polarization process.