No abstract

No abstract

The dielectric properties of cobalt phthalocyanine are investigated in the frequency range 50-5x 105 Hz and within the temperature range 293-363 K. The frequency dependence of the AC impedance could be expressed by the complex plane of the complex impedance. Analysis of the AC conductivity reveals semiconducting features based predominantly on the hopping mechanism. The relaxation time, derived from the experimental results, shows a thermally activated process.

No abstract

The dielectric constant and the dielectric loss of potassium acetylacetonate, K(acac), are measured as a function of both temperature and frequency. A peak value is obtained at the a critical temperature T^ = 313 K. X-ray analysis revealed that at Τ , K(acac) undergoes phase transition from orthorhombic to triclinic structure. The Cole-Cole diagrams have been used to determine the molecular relaxation time τ. The temperature dependence of τ is expressed by thermally activated process. The impedance spectra in the frequency range from 50 Hz to 500 kHz plotted in the complex plane show semicircles. The conduction mechanism, below Τc , is predominantly operating at the surface. Above Τc , the conduction is proceeding in the bulk material with contribution from the surface.

The objective of the current study was to find out the effect of aluminum on the seedlings pre-treated by two levels of boron concentrations 4μM or 32μM grown in hydroponic solution of Al from 100-500μMAl for 3 days. Data revealed that Al had a negative effect on fresh, dry weight, water content, carbohydrate, protein and amino acids including proline constituents and changes in protein profile were analyzed of fourteen day-old Al-tolerant (‘Sakha 93’) cultivar of Triticum aestivum. The effect of boron treatment was pronounced at 32μM B level. Pretreatment of 4µM B and exposure to 500 µM Al revealed that insoluble protein increased soluble, total protein and total soluble sugars decreased in comparison to Al treatment only. Levels of amino acids most notably proline, the glutathione forming amino acids cysteine, glycine and glutamic and the branched chain amino acids (BCAAs) leucine, isoleucine and valine were increased under Al stress. The obtained results showed the high resistance of ‘Sakha 93’ cultivar to aluminum stress. Aluminum detoxification coincides with increased TSS, TP, Pro, BCAAs contents and polypeptides in the root to cope with alleviation of Al-stress; boron may have a role in this concern.

The paper reports dielectric measurements carried out for isatomalononitrile at different temperatures (346 to 383 K) and various frequencies (50 to 5 x 105 Hz). Kramers-Kronig relations are used to ascertain the magnitude of the dc conductivity and to enhance the reliability of dielectric measurements. The analysis of the results shows that there exist certain very slow dielectric phenkena in isatomalononitrile. The frequency dependent conductivity of isatomalononitrile increases approximately linear with frequency. The frequency exponent has the value of 0.5, independent of temperature. PACS numbers: 77.22.-dThe dielectric properties of solids can be described by their complex capacitance defined by the expression where C' and C" are the real and imaginary components of the complex capacitance; C(ω) is the ordinary capacitance, G(ω) is the effective alternating-current conductance and ω is the angular frequency.The complex dielectric permittivity ε* (ω) is related to C* (ω) by a geometrical factor and the corresponding expression for the complex dielectric susceptibility X* may be obtained from ε* (ω) by subtracting the dc contribution σ0 /ω and the "high frequency" permittivitywhere the real and imaginary components of x* (ω) and ε* (ω) are Kramers-Kronig (KK) compatible.In the case of "universal" form of frequency dependence of both X'(ω) and X"(ω) on con -1 , where the value of n being in the range of (0,1), their ratio is independent of frequency [1] (477)

Current density-voltage characteristics were obtained from 2,6-diamino anthraquinone samples using ohmic aluminium electrodes. Results showed that at low voltage the conduction process was ohmic, while at high voltage space-charge-limited conduction controlled by a single dominant trap level was presented. Thickness dependence measurements proved that the trapping sites were located at a discrete energy level. The transition voltage, V, between ohmic and space-charge-limited conduction was approximately proportional to the square of the sample thickness and was found to be temperature independent. The temperature dependence of ohmic and space-charge-limited current densities have been investigated. The results were interpreted in terms of extrinsic nature of ohmic conduction. Traps with density =2 x 102 4 m -3 l o c a t e d a t 0 . 5 0 ± 0 . 0 3 e V b e l o w t h e c o n d u c t i o n band edge have been observed.