Modifying of the dielectric properties of adsorbed water in the force field of a solid surface

The results of thermodynamic and acoustoelectric studies of changes in the dielectric properties of adsorbed water under the influence of a solid surface force field are presented. It is noted that the dielectric properties of adsorbed water depend not only on the characteristic size of the system, but also on the interaction energy with the solid surface. Near the hydrophilic solid surface, the density of adsorbed water is increased and the mobility of molecules is reduced. The opposite effect occurs for hydrophobic surfaces. The frequency dependences of the dielectric properties of adsorbed water, as in the case of water in the solid and liquid phase, can be characterized using Debye relaxation theory. It is shown that a significant increase in the orientational dielectric relaxation time in adsorbed water can be explained by taking into account the energy of interfacial boundaries.

Dielectric Relaxation Studies Between Brompheniramine with 1-Butanol, 1-Pentanol and 1-Hexanol at 303K

The dielectric relaxation studies are vital in analyzing the strength of the inter molecular interaction between the binary liquid systems [1-4]. Jyostna et al. [5] reported thermodynamic parameters of isoamyl alcohols and mono clinic aromatic liquid mixtures. Shakila et al. [6] studied the dielectric properties of aromatic alcohols and aliphatic amines at different temperatures. In general, dielectric relaxation time varies with the inter molecular forces acting between the molecules in the selected liquid mixtures. Brompheniramine is one of the critical compounds of an amine group with spectacular applications, including pharmaceutical industries [7]. Higher carbon chain length alcohols are having self associated and proton donating ability in the liquid mixtures. The variations in the dielectric constant (є’), dielectric loss (є’’), static dielectric constant (є0) and the dielectric constant at an optical frequency (є∞) with a range of brompheniramine concentrations with 1-butanol,1-pentanol and 1-hexanol systems are useful in the applied research and chemical industries. Moreover, the variations in the dielectric constant and dielectric relaxation time should be useful in the analysis of intermolecular interaction between the functional group of the selected liquid mixtures. This research work attempts to analyse the intermolecular interaction between the brompheniramine and 1-butanol,1-pentanol and 1-hexanol at 303K using time domain reflectometry techniques.

AC conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses

The present paper reports the ac conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses at various temperatures and frequencies. It was found that ac conductivity increases on increase of frequency, temperature as well as Bi content. The increase in conductivity is due to the formation of lower energy Se–Bi and Te–Bi bonds which takes the system to a stable lower energy configuration. The values of frequency exponent (s) were calculated and it was found that samples obey CBH model of conduction. Density of states (N(Ef)) near the fermi level were calculated at different temperatures and it was found that addition of Bi increases the number of localised states in the tails which leads to increase in ac conductivity. Further, it was found that dielectric parameters increase with increase in temperature. However, a decrease in both dielectric constant (ε′) and dielectric loss ((ε″) was observed with increase in frequency. Beside this, dielectric relaxation time (τ) and activation energy of relaxation (∆Eτ) were also determined for both the samples under study and was found to be lower for Se68Te20Bi12 glass.

STRUCTURAL, OPTICAL, ELECTRICAL AND DIELECTRIC PROPERTIES OF PVA-YCl3 FILMS

Polyvinyl alcohol (PVA) films doped with 10[Formula: see text]wt.% of yttrium chloride (YCl[Formula: see text] have been made by casting from their aqueous solutions. The structure of un-annealed and annealed PVA-YCl3 films was studied using X-ray diffraction (XRD) patterns and Fourier-transform infrared spectroscopy (FTIR). Both FTIR and XRD revealed that the crystalline ratio of the studied samples increased due to the effect of annealing. The effect of annealing on the optical properties has been studied. Dispersion of the refractive index was described using the single oscillator model. The single oscillator energy and the dispersion energy were estimated. The calculated optical band gap of all PVA-YCl3 films was 5.0[Formula: see text]eV. The behavior of ac conductivity showed that the conduction mechanism of PVA-YCl3 films was correlated barrier hopping model. The dielectric constant and dielectric loss index were decreased with the increase of the field frequency. The electric modulus granted a straightforward technique for assessing the dielectric relaxation time. The calculated activation energy obtained from the electric modulus mechanism was 0.172[Formula: see text]eV.

Complex and thermodynamic properties of polar liquids using time domain reflectometry

The study of complex properties in a binary mixture of 1,2-dichloroethane (DE) and [Formula: see text]-methylformamide (NMF) polar liquids has been carried out in the frequency range of 10[Formula: see text]MHz to 30[Formula: see text]GHz for 11 different concentrations using time domain reflectometry technique at 283, 288, 293 and 298[Formula: see text]K temperatures. Complex property of binary liquids indicates the type of distribution of the dielectric relaxation time. The Bruggeman parameter gives the information about molecular interactions within binary polar liquids. Thermodynamic parameter deals with the passing of a dipole across a potential barrier which separates the minima of energy.

Influence of Grain and Grain Boundary Interfaces on Dielectric Relaxation of Ceria Nanocrystals Using Modulus Formalism Under Biased and Equilibrium Conditions

Dielectric relaxation of ceria nanocrystals under biased condition for different grain sizes was in this study evaluated in modulus formalism using impedance spectroscopy. Prior to the impedance measurements, the ceria sample was calcined at 200 °C for 30 min and pressed into cylindrical pellets with 8 mm diameter and 1 mm thick by applying uniaxial four-ton pressure using a hydraulic press. This was then sintered at 300 °C, 450 °C, 600 °C and 900 °C for 30 min. Systematic analysis of modulus formalism data using commercial Z-view and Z-plot software's permitted, reliable extraction of dielectric relaxation time (τ) of ceria nanocrystals. The observed dielectric relaxation time (τ) at equilibrium condition varied from 10–5 to 10–3 s when the grain size of ceria nanocrystals was increased from 9 nm to 29 nm. But when the DC bias voltage was applied, the same dielectric relaxation time (τ) was tuned to ∼10–4 s for all the grain sizes of ceria nanocrystals, because of Schottky grain boundary potential barrier height (φb) suppression.