Влияние электронного облучения на диэлектрические характеристики монокристаллов AgGaSe-=SUB=-2-=/SUB=-

The effect of various doses of electron irradiation on the dielectric constant and electrical conductivity of triple nonlinear AgGaSe2 crystals at different measuring field frequencies in the temperature range of 100-300 K has been investigated. It has been found that single-crystal irradiation leads to a dielectric constant decrease and an electrical conductivity significant increase. It is shown that the dielectric constant and electrical conductivity increase with an temperature increase. It has been established that AgGaSe2 crystals are characterized by the presence of several conductivity types. A significant frequency dispersion of the dielectric properties of the investigated crystals was found.

Evaluation of Electrical Characteristics for PMMA-TiO2 Nanocomposites Used in Dentistry

In this paper, it is studied the influence of TiO2 nanoparticles content (0.2-5% wt:wt) on the electrical conductivities and the dielectric constants of poly (methyl methacrylate) (PMMA) nanocomposites used for 3D printing in dentistry. The nanocomposites films, which have been obtained applying the casting method followed by UV exposure, were mounted in a four electrodes cell for the electrochemical a.c. impedance analysis. The experimental data showed that both the dielectric constant and the electrical conductivity increase with increasing amounts of nano-TiO2 in nanocomposites. However, the change in the electrical conductivity is not significant for less 1% nano-titania added.

Thermal and Electrical Conductivity of Unsaturated Polyester Resin Filled with Copper Filler Composites

Thermal and electrical conductivity of unsaturated polyester resin with copper filler composite material are investigated both theoretically and experimentally. In the experiments, polyester matrix is combined with dendrite-shape copper to determine the effects of both filler size and content on thermal and electrical conductivity, respectively. It is observed that the increase in the concentration causes the thermal and electrical conductivity of composite mixture to grow up. It has also been observed that the both thermal and electrical conductivity increase with increasing filler particle size.

Structural, Optical and D.C Electrical Properties of (PVA-PVP-Y2O3) Films and Their Application for Humidity Sensor

The films prepared by casting method with different percentages of nano yttrium oxide (0, 3, 6, 9 and 12) wt%, where optical microscope images show the yttrium nanoparticles form a continuous network inside the polymers when the proportion of (12 wt%). FTIR spectra shows shift in peak position as well as change in shape and intensity, comparing with pure (PVA-PVP) films, this indicates decoupling between the corresponding vibrations of two polymers and yttrium nanoparticles, and we noted that there is a decrease in transmittance at increasing the proportion of yttrium oxide nanoparticles. Scanning electron microscopy shows the surface morphology of the (PVA-PVP-Y2O3) films many aggregates or chunks randomly distributed on the top surface, homogeneous and coherent. The absorbance increases with increase the weight percentages of nano yttrium oxide. The absorption coefficient, extinction coefficient, refractive index, real and imaginary parts of dielectric constants and optical conductivity are increasing with increase the weight percentages of yttrium oxide. The energy band gap decreases with increasing the weight percentages of yttrium oxide. The D.C electrical conductivity increase by increasing yttrium oxide concentrations and temperature. The activation energy decreases by increasing yttrium oxide concentrations. The resistance of the sensor decreased as humidity increased.

The Band Structure and Electronic Density of States of Thermoelectric Co-Doped Magnesium Silicide

Magnesium silicide (Mg2Si) has been identified a promising advanced thermoelectric material in temperature range from 300 to 700K. In order to understand thermoelectric properties of Co-doped magnesium silicide, the band structure and electronic density of states have been calculated using a first-principle pseudopotential method. It is shown that the band gap gradually decreases, at the same time degeneracy of the band and the density of states at the fermi level increase as the content of cobalt increases. It was properly predicted that the Seebeck coefficient and electrical conductivity increase, and thermal conductivity decreases as the content of cobalt increases.

Carbon Nanotube Dispersion in Epoxy Nanocomposites with Clay

ABSTRACTClay particles were used to facilitate the dispersion and network formation of single-walled carbon nanotubes (SWNTs) in an epoxy matrix. In the presence of clay, electrical conductivity increase and percolation threshold reduction for SWNT/epoxy composites were achieved simultaneously. These improvements are due to better SWNT dispersion, as evidenced by optical microscopy and scanning electron microscopy. Dynamic mechanical analysis (DMA) shows that mechanical properties of the composites without clay could be improved by clay addition. SWNTs appear to have an affinity for clay that causes them to become more exfoliated and better networked.