Influence of BaO Doping on the Structural, ac Conductivity, and Dielectric Properties of BiFeO3 Multiferroic Nanoparticles

The Bi1 − xBaxFeO3 (BiBaFeO3) multiferroic nanoparticles with different Ba molar concentrations were fabricated in reliance on the solid-state reaction technique. Nanostructures of the prepared samples were confirmed by X-ray diffraction (XRD) together with Fourier transforms infrared (FTIR) spectroscopy, whereas the ac conductivity, dielectric and ferroelectric features were examined depending on the RLC Bridge, and Sawyer–Tower circuit. XRD patterns displayed the creation of rhombohedral–hexagonal single-phase of BiBaFeO3. The formation of BiBaFeO3 multiferroic nanoparticles was confirmed by FTIR spectra. Curie temperature (TC) was observed around 1121–1189 K. Ferroelectric polarization was enhanced with remnant polarization of 88.8 µC/cm2 by Ba2+ ions substitution at x = 0.15 mol%. Besides, ac electrical conductivities as a function of frequency as well as temperature were reported for all BiBaFeO3 multiferroic nanoparticles, which exhibit a strong frequency dependence with conduction mechanism is the correlated barrier hopping (CBH) model. The obtained high polarization and Curie temperature enhance their use in information storage devices.

Estimation of The Electrical and Dielectric Properties For Se98Te2 and Se96Te2X2 (X = Zn and Cd) Amorphous Films.

Bulk glassy Se98Te2 and Se96Te2X2 (X = Zn and Cd) were prepared by melting quenching method. Thin films of various thicknesses (200 – 670 nm) were obtained by the thermal evaporation method. The structure of the prepared compositions was investigated by X-ray and EDX analysis. We studied the effect of Zn and Cd addition on the electric and dielectric properties of Se98Te2 thin films. Our measurements were studied in the temperature range (298-323K) below the glass transition temperature and frequency range (100 Hz-1 MHz). DC conductivity showed a single conduction mechanism by hopping of charge carriers at the band edges for the studied system. The dependence of Ac conductivity on frequency is linear with frequency exponent s lies very close to unit and is independent of temperature. This can be explained by the correlated barrier hopping (CBH) model. The dielectric constant ε1 and dielectric loss ε2 noticed to decrease with frequency and increase with temperature. The maximum barrier height Wm was calculated according to Guinitin.

Electrical conductivity and vibrational studies induced phase transition in [N(C3H7)4]2ZnBr4 compound

Bis-Tetrapropylammonium tetrabromozincate was synthesized and characterized by X-ray powder diffraction, as well as vibrational and impedance spectroscopy. Rietveld’s refinement of X-ray diffractogram confirmed the crystallization of the compound through the monoclinic system (space group [Formula: see text]. A temperature study of Raman scattering revealed two phase transitions at approximately [Formula: see text] = 340 K and [Formula: see text] = 393 K. The wavenumber and the line width’s evolution as a function of temperature showed some peculiarities associated with these transitions, which suggests that they are governed by the reorientation of the organic part [N(C3[Formula: see text]][Formula: see text]. The complex impedance plotted as a double semicircular arc in the studied temperature range and the centers of these semicircles lie below the real axis, which indicates that the material is an on-Debye type. These semicircular arcs are related to the bulk and the grain boundary effects. Furthermore, the alternating current conductivity of [N(C3[Formula: see text]]2ZnBr4 obeyed Jonscher’s law: [Formula: see text] = [Formula: see text] and the conduction could be attributed to the correlated barrier hopping (CBH) model in both region(I) and (II) and the Non-overlapping Small Polaron Tunneling (NSPT) in region (III).

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.

Impedance spectroscopic study on hybrid phthalocyanine/lead sulphide nanocomposite film

A unique organic/inorganic nanocomposite of non-aggregated lead sulphide (PbS) quantum dots (QDs) dispersed within a spun film of non-peripherally octakis(hexyl)-substituted metal-free phthalocyanine (C[Formula: see text]H[Formula: see text]Pc) has been prepared at room temperature by a simple and low-cost method. The frequency response of alternating current (AC) conduction in a 130 nm thick C[Formula: see text]H[Formula: see text]Pc /PbS film sandwiched between the indium-tin-oxide (ITO) and aluminum (Al) electrodes is found to obey the universal power-law. The cryogenic study of AC conduction reveals that the correlated barrier hopping (CBH) model closely fits to the experimental data at temperatures below 240 K. The parameters obtained by fitting the CBH model point out that the hopping process cannot take place directly between neighboring PbS QDs but involves the localized states within the matrix.

Control blade history reactivity and pin power effects evaluated with Westinghouse BWR nodal core simulator POLCA8

The so-called “Control Blade History” (CBH) effect has always posed a serious challenge for any nodal core simulator in performing Boiling Water Reactor (BWR) core analyses. In this paper a method to handle such CBH effects is proposed based on the idea of interpolating lattice physics data between two extreme cases with regard to CBH, namely, the case with the control rod always inserted during depletion and the case with the control rod never inserted during fuel irradiation. In POLCA8, the latest upgrade of the Westinghouse BWR nodal core simulator POLCA, one applies the methodology to macroscopic cross sections, discontinuity factors, pin powers and detector constants. Overall, the proposed CBH model performs very well in terms of predictive accuracy of reactivity and pin powers although simultaneous presence of control rods (CRs) and burnable absorbers (BAs) still poses a challenge due to some observed interference of their impact on reactivity. Applying the CBH model for pin power reconstruction is particularly promising and provides excellent prediction accuracy in the vicinity of the CR and at the point of CR withdrawal being the most challenging and critical condition with regard to CBH.

Electric and dielectric properties of CdSO4-doped borate glasses

A system of (100-x)B2O3⋅xCdSO4glasses (0 [Formula: see text]x [Formula: see text] 40) is set by the ordinary quenching method. Density ([Formula: see text]), molar volume (V[Formula: see text]) and oxygen ion density (N[Formula: see text]) are found to increase with the increase of CdSO4in the samples. The dc conductivity ([Formula: see text]) and the ac conductivity ([Formula: see text]) are measured in the temperature range from 308 to 735 K. [Formula: see text] is found to follow the thermal activation Arrhenius relation with activation energies between 0.36 and 0.76 eV. Ac conductivity and the exponent factor (s) confirm that the CBH model is the origin of the conduction. The dielectric constant ([Formula: see text]) and loss ([Formula: see text]) are studied as a function of the temperature and frequency. The dielectric data are fitted according to the Cole–Cole equations. The values of [Formula: see text] parameter are found to vary between 0.2 and 0.58 which means that these glasses exhibit a wide distribution of relaxation times.