Dielectric Relaxation Studies Research Articles

Temperature-Dependent Dielectric Relaxation Measurements of (Betaine + Urea + Water) Deep Eutectic Solvent in Hz-GHz Frequency Window: Microscopic Insights into Constituent Contributions and Relaxation Mechanisms.

A combined experimental and simulation study of dielectric relaxation (DR) of a deep eutectic solvent (DES) composed of betaine, urea, and water with the composition [Betaine:Urea:Water = 11.7:12:1 (weight ratio) and 9:18:5 (molar ratio)] was performed to explore and understand the interaction and dynamics of this system. Temperature-dependent (303 ≤ T/K ≤ 343) measurements were performed over 9 decades of frequency, combining three different measurement setups. Measured DR, comprising four distinct steps with relaxation times spreading over a few picoseconds to several nanoseconds, was found to agree well with simulations. The simulated total DR spectra, upon dissection into three self (intraspecies) and three cross (interspecies) interaction contributions, revealed that the betaine-betaine self-term dominated (∼65%) the relaxation, while the urea-urea and water-water interactions contributed only ∼7% and ∼1%, respectively. The cross-terms (betaine-urea, betaine-water, and urea-water) together accounted for <30% of the total DR. The slowest DR component with a time constant of ∼1-10 ns derived dominant contribution from betaine-betaine interactions, where betaine-water and urea-water interactions also contributed. The subnanosecond (0.1-0.6 ns) time scale originated from all interactions except betaine-water interaction. An extensive interaction of water with betaine and urea severely reduced the average number of water-water H-bonds (∼0.7) and heavily decreased the static dielectric constant of water in this DES (εs ∼ 2). Furthermore, simulated first rank collective single particle reorientational relaxations (C1(t)) and the structural H-bond fluctuation dynamics (CHB (t)) exhibited multiexponential kinetics with time scales that corresponded well with those found both in the simulated and measured DR.

Dielectric relaxation studies in Sm2O3 doped boro-zinc-vanadate glasses

In this work, the conventional melting procedure was adopted to synthesize glasses with a composition of (ZnO)0.3 – (V2O5)0.3 – (B2O3)0.4-x – (Sm2O3)x, x = 0.002, 0.005, 0.007, 0.01 and 0.02 mol%. The dielectric properties of these glasses were measured. The dielectric constant (εʹ) and dielectric loss (εʹʹ) of glasses are found to vary in the range from 1.9177x102 to 3.9456x103 and from 1.5751 to 6.9095x105 respectively for the temperature range 343 K – 573 K and frequency range 50 Hz to 10 MHz. With increase of frequency, both dielectric constant and loss decreased and increased with increase of temperature. The analysis of dielectric constant and dielectric loss confirmed that the phenomenon of dielectric relaxation is mainly due to the frequency-dependent polarization mechanism. Electric modulus and impedence spectroscopy revealed non-Debye type and a single phase relaxation process. Activation energy for dc conductivity and dielectric relaxation are found to be of same size indicating that the potential barrier encountered by the charge carriers is same in both the processes. The master curves suggested that temperature-independent relaxation is occurring in the present glasses. The high values of measured dielectric parameters suggest that the present glasses are suitable in semiconducting and energy storage applications.

Structural, microstructure, dielectric relaxation, and AC conduction studies of perovskite SrSnO3 and Ruddlesden-Popper oxide Sr2SnO4.

Here, we report a comparison study on the synthesis and characterization of perovskite SrSnO3 (SSO) and Sr2SnO4 (S2SO). Rietveld refinement studies were performed on both prepared samples and suggest that they crystallized in cubic (SSO) and tetragonal (S2SO) structures. Fourier-transform infrared (FTIR) and Raman spectroscopy studies supported the XRD observations. Improved dielectric parameters were observed for S2SO over SSO due to differences in dislocation density, larger crystallite size, and denser microstructure. The electrical conduction and relaxation processes followed the Arrhenius type in both samples through the migration of oxygen vacancies via the Sn-site and the transfer of electrons between the Sn sites in two different temperature regions. These processes in the samples occurred via correlated barrier hopping (CBH) in SSO and the non-overlapping of small-polaron tunnelling (NSPT) in S2SO. The conduction and relaxation processes had similar sources of charge carriers but differed in the concentration and mobility of charge carriers. The presented materials can be utilized for dielectric capacitors, sensors, and mixed ionic and electronic conductor-based electrodes in IT-SOFC applications.

Aggregation Behavior of Ethoxylated Phytosterol Surfactants in Different Protic Solvents: An Insight from Dielectric Relaxation Studies.

The micellar aggregation behavior of biocompatible surfactants, phytosterol ethoxylates (BPS-n, n is the oxyethylene (EO) chain length), containing polyoxyethylene chains in four organic solvents (glycerol (G), ethylene glycol (EG), formamide (FA), and N,N-dimethylformamide (DMF)) was studied by dielectric spectroscopy in the frequency range of 40 Hz to 110 MHz. Only the BPS-n/EG and BPS-n/G systems show distinct dielectric loss peaks near 104 Hz, indicating that BPS-n forms micellar aggregates in EG and G solvents, and the interfacial polarization (IP) between the aggregates and solvents leads to this relaxation. The dielectric spectra were analyzed based on the IP theory and a columnar dispersion model. The dielectric parameters of micelles, the permittivity and conductivity of micelles and solvents, and the volume fraction of the aggregates in solvents were calculated. On this basis, the binding numbers of each EO group on the hydrophobic chain to the solvent molecules EG and G were calculated to be 0.42 and 0.22, respectively. It was suggested that the aggregation appears to be related to the magnitude of the hydrogen bonding interactions. The lower number of EO group-binding solvents is because of the strong steric effect of alcohol solvents and the magnitude of the hydrogen bonding force.

Structural, optical, dielectric relaxation, complex impedance and modulus spectroscopic studies of pure and glutamic acid doped potassium dihydrogen phosphate

Structural, optical, dielectric relaxation, complex impedance and modulus spectroscopic studies of pure and glutamic acid doped potassium dihydrogen phosphate

Synthesis, characterization and dielectric relaxation studies of graphene quantum dots prepared by hydrothermal treatment method

Zero dimensional graphene quantum dots (GQDs) exhibit fascinating chemical and physical properties discovered by Pan et al., in 2010, due to the quantum confinement and edge effect. GQDs have been synthesized by hydrothermal treatment method from graphite powder as low cost, easy process, and large amount with high production yield. The functional groups of GQDs on the surface sites of carbon atoms have been studied through Fourier transform infrared spectroscopy (FTIR) analysis. X-ray diffraction (XRD) pattern of GQDs shows the broad diffraction at 2 θ = 24.47 ° with 0.36 nm an interlayer distance confirming the formation of the GQDs. Raman analysis reveals that GQDs show both D and G bands mostly the armchair edges. UV–visible spectra show absorption peak at 287 and 330 nm credited to π → π * and n → π * transitions due to the presence of conjugated carbon–carbon bonds and carbonyl groups. The particle size of GQDs is found below 5 nm from high- resolution transmission electron microscopy (HR-TEM) image. Scanning electron microscopy shows the surface morphology of GQDs are crumpled and aggregated thin sheets. Dielectric properties of synthesized GQDs have been studied in the range frequency between 0.01 and 105 Hz at different temperatures (25, 50, 75, and 100 °C). The dielectric relaxation mechanism is explained in the framework of dielectric loss tangent (tanδ), permittivity and electrical conductivity. The dielectric loss tangent increases with frequency and maximum peak decreases with frequency at all different temperatures due to present of polar groups in GQDs. Dielectric permittivity decreases with frequency at all different temperatures due to charge orientation and rotation of dipole moments. The electrical conductivity increases with frequency at all different temperature due to the GQDs is highly conductive nature. So synthesized GQDs can be used in electrical and electronic materials.

Dielectric relaxation and thermodynamic study of aqueous Glycine using time domain reflectometry technique

Using the Time Domain Reflectometry technique in the frequency range of 10 MHz to 50 GHz, the complex permittivity spectra of Glycine (Gly) with water combination have been determined over the complete concentration range of mole fractions and in temperature range of 10–25 °C. The Cole-Davidson model was used to fit the intricate permittivity spectra for Gly and water.The non-linear least square fit method has been used to compute the static dielectric constant (ε0), relaxation time (τ), effective Kirkwood correlation factor (geff), excess permittivity (ε0E), (1/τ)E excess inverse relaxation time (1/τ)E and Bruggeman factor (fB). An automated density and sound velocity meter, the Anton Paar DSA 5000 M and viscosity with Lovis 2000 M/ME, was used to measure the density, sound velocity, and viscosity of aqueous solutions. FT-IR spectra are used to identify the conformation assessments of hydrogen bonding development between complicated mixtures.

Structural and dielectric relaxation studies of 1, 4, and 1, 3 -butanediol–1, 4-dioxane mixtures using TDR technique

Time domain reflectometry (TDR) was used to examine the complex dielectric permitivity spectra (CPS) of binary mixtures of 1,4, and 1,3 butanediol (BD) with 1,4 Dioxane (Dx) at high frequencies (10 MHz–50 GHz). Both systems show the Cole–Davidson type of relaxation process. The least squares fit (LSF) method is applied to compute dielectric relaxation parameters from the CPS. The interest of the ongoing research is to understand the molecular associations, orientation of electric dipoles, and change in electric dipole density in the liquid mixture with the help of excess dielectric parameters, Bruggeman factor (fB) and the Kirkwood correlation factor for both systems.

Ternary Mixture of Pentanamide in Solvent Analogy with Halogenated Phenol: Experimental, Theoretical, and In Silico Biological Studies.

This research describes the preparation of mixtures of new halogen-substituted phenol derivatives and their effects due to linkages with a fatty amide (pentanamide). The molecules were optimized using DFT, and the vibrational and electronic analysis was done subsequently. The energies of frontier molecular orbitals (FMOs) were used to estimate the global chemical reactivity parameters as we suggest that hydrogen-bonded networks may have contributed to the stability and reactivity of the compound. In addition to the experimental investigation, dielectric parameters were calculated. Fukui functions were analyzed to study the chemical reactivity. To get insight into interactions of σ → π* orbitals, natural bond orbital calculations were done. Additionally, surface analysis of the MEP and Hirshfeld charges were performed at the equivalent DFT levels. The research also indicated that both (interaction region indicator) IRI and (electron delocalize range) EDR would proficiently identify chemical-bonding and weak interaction regions, providing a significant advantage in exploring diverse chemical systems and reactions. This indicated that compounds could diffuse through noncovalent interactions, including intramolecular hydrogen bonding. Dielectric relaxation studies taken at five distinct molar ratios identified significant dielectric properties such as ε', ε″, ε0, and ε∞. The PA with FP, CP, BP, and IP molecules has potential antiviral and antioxidant benefits for carbonic anhydrase, with favorable drug-like features and diverse biological benefits. Pharmacological effects were forecasted using the PASS server, and these molecules exhibited favorable pharmacokinetic properties.

Dynamic memory tuned by frequency in a homologous thermotropic liquid crystal.

With scaling of dynamic RAM and NAND memory technologies reaching a limit, there is a need for dynamic memory with high density. In this work, an investigation on existence of dynamic memory feature in a frequency tuned homologous series of thermotropic liquid crystals has been carried out. A homologues series of five thermotropic liquid crystalline compounds comprising of 4-butyl benzoic acid and various alkyloxy benzoic acids are prepared, and all these mesogens exhibit only nematic phase. Liquid crystal dynamic memory storage setup consists of a conducting transparent glass cell with two indium tin oxide coated transparent glass plates acting as electrical electrodes in which the selected thermotropic liquid crystal is filled by capillary action. The temperature dependent dielectric relaxation studies enable to elucidate the relaxation frequency of each of these mesogens in nematic phase. The liquid crystal at different temperatures is excited with the relaxation frequency at various chosen fields, and the dielectric hysteresis is recorded. The magnitude of the hysteresis loop is directly proportional to the memory storage capacity. The main objective of this work is observation of dynamic memory storage in liquid crystals exhibiting nematic phase, at different frequencies in a thermotropic liquid crystal as the ingredient in a conducting polyamide buffed glass cell excited by an external electrical dc stimulus. The variation of the hysteresis loop with varying field; temperature and frequency are also studied and reported in this work.

Spectroscopic measurement and dielectric relaxation study of vegetable oils

The purpose of the current study is to investigate the qualitative characterization of nine different pure vegetable oil samples using dielectric spectroscopy which is a vastly resourceful and reasoned technique in the temperature range 0 ℃ to 25 ℃. Time-domain reflectometry technique is applied up to the microwave frequencies of 50 GHz for the first time for qualitative characterization of the selected vegetable oil samples with a special focus on the variances of dielectric properties like dielectric permittivity (ε′), dielectric loss (ε″), relaxation time concerning temperature and other physiochemical properties of the vegetable oil specimens.The experimental methodology involves the use of time-domain reflectometry (TDR) measurements up to the scale of 50 GHz done to analyse the aspects like lower and higher scales of values towards the static dielectric permittivity (εs) and relaxation time (τ) (ps) to further meaningfully compare and correlate this values with the fatty acid profiles of each of the nine vegetable oil samples to reason and draw comparative inferences about the quality aspects of vegetable oils. Microwave TDR studies provide an effective, alternate, simple, rapid, and viable way to exercise quality control and actuate data regarding the quality status of vegetable oils. Variances of dielectric permittivity (ε′) concerning dielectric loss (ε″) are graphically interpreted using the Cole Davidson model. The static dielectric permittivity (εs) was further recertified and measured accurately by using a precision LCR meter. Thermodynamic properties of all the nine vegetable oil samples like enthalpy (ΔH) (kJ/mol) and entropy of activation (ΔS) (J/mol ∙ K) are also calculated to further insight the dependence of dielectric properties of these oil samples concerning temperature.This dielectric spectroscopic study affirms the association of the quality aspects of these nine vegetable oil samples with their dielectric properties by providing meaningful correlations, comparatives and concurrencies of dielectric properties concerning the physiochemical properties which are a part of fatty acid profiles of these samples, which is a novel aspect of this study. The Cole-Cole plot underlines the tendency of realignment of dipoles as per the applied field. The complex permittivity spectra indicate the dwindling nature of molecular alignment including a slow decline to average coinciding values depending on the molecular bonding pattern of vegetable oil samples. The activation energy (ΔH) in (kJ/mol) is calculated for all the samples which are indicative of endothermic nature which experimentally proves that high energy is required for rotation of unsaturated oil sample molecules with low relaxation times.The highlight of the current dielectric spectroscopic study is that it conclusively divides the nine vegetable oil samples into two groups based on the dielectric property of relaxation time. The vegetable oil samples with higher relaxation times were measured in ps [soyabean oil (398.5), groundnut oil (412.5), flaxseed oil (318.4), and castor oil (305.3)] and the oil samples with lower relaxation times [safflower oil (37.91), sunflower oil (30.6), walnut oil (22.4) and sesame oil (38.4)] and correlate this dielectric aspect with the aspect extent of the presence of oleic acid: C18H34O2, linoleic acid: C18H32O2, linolenic acid: C18H30O2 and ricinoleic acid C18H34O3 alongside the percentage of unsaturation present in the fatty acid profile of each sample. Saturated fatty profile of coconut oil (percentage of saturation 82.5) with low relaxation time (41.8) ps and its concurrency concerning the extent of percentage presence of lauric acid C12H24O2 (52 ps) myristic acid: C14H28O2 (21 ps) is also correlated. The current dielectric spectroscopic study further highlights and compares the variances of dielectric permittivity of the nine vegetable oils samples with the percentage of unsaturation /saturation to infer upon the correlation with the fatty acid profile of these oil samples.

Synthesis and Dielectric Relaxation Studies of KxFeyTi8-yO16 (x = 1.4–1.8 and y = 1.4–1.6) Ceramics with Hollandite Structure

Some solid solutions with the chemical composition KxFeyTi8-yO16 (KFTO) and a hollandite-like structure were successfully synthesized by modified sol–gel method. The obtained powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The ceramic pellets based on KFTO powders were obtained by compressing and sintering at 1080 °C for 4 h. The sinters were characterized by X-ray and impedance spectroscopy. XRD results show that KFTO powders have a mono-phase tetragonal structure at x = 1.4–1.8 and y = 1.4–1.6. However, it was recognized that the hollandite-like phase could be broken during sintering to form TiO2 and Fe2TiO5 crystals distributed throughout the volume of the ceramics. A frequency dependency of dielectric properties for the sinters was studied by impedance spectroscopy. It was found that an increase in the TiO2 (rutile) phase during the sintering contributes to a decrease in dielectric losses. At the same time, the KFTO ceramics with reduced content of potassium had increased permittivity. The contribution of electron-pinned defect dipoles (EPDD) and internal barrier layer capacitance (IBLC) in the permittivity of the obtained ceramics was estimated using the Havriliak–Negami equation. It is shown that the KFTO ceramics have the polydisperse characteristic of dielectric relaxation. The observed grain and grain boundary dipole relaxation times were 1.03 × 10−6 to 5.51 × 10−6 s and 0.197 to 0.687 s, respectively.

Graphene Oxide-Grafted Hybrid Diblock Copolymer Brush (GO-graft-PEG6k-block-P(MA-POSS)) as Nanofillers for Enhanced Lithium Ion Conductivity of PEO-Based Nanocomposite Solid Polymer Electrolytes.

Nanocomposite solid polymer electrolytes (NSPEs) with PEO as the matrix and (i) GO or (ii) GO-graft-PEG6k or (iii) GO-graft-PEG6k-block-P(MA-POSS) as nanofillers have been fabricated to elucidate the impact of the filler morphology on the lithium ion conductivity. GO-graft-PEG6k was obtained by grafting PEG6k onto GO via esterification. GO-graft-PEG6k-block-P(MA-POSS) was prepared via surface-initiated atom transfer radical polymerization. Fourier-transform infrared spectroscopy revealed enhanced salt dissociation and complexation between the filler and PEO host that could be attributed to Lewis acid-base interactions. Electrochemical impedance spectroscopy revealed the improved ion conductivity of the fabricated NSPEs as compared with the pristine PEO-LiClO4. As an example, at 50 °C, the ion conductivity increased to 4.01 × 10-5 and 6.31 × 10-5 S cm-1 with 0.3% GO and 0.3% GO-graft-PEG6k, respectively, from 2.36 × 10-5 S cm-1 of PEO-LiClO4, suggesting that the filler with brush-like architecture (GO-graft-PEG6k) is more efficient in enhancing the ion conductivity. Further increase in filler content resulted in lowering of the ion conductivity that could be ascribed to aggregation of the filler. The most dramatic impact on conductivity was observed with the incorporation of brush-like GO-graft-PEG6k-block-P(MA-POSS) as a nanofiller (3.0 × 10-4 S cm-1 at 50 °C with 1.0 wt % filler content). The increase in ion conductivity in the current systems, as opposed to the conventional view, could not be correlated with the content of the amorphous phase of the matrix. The conduction mechanism is still unclear; nevertheless, it could be assumed that in addition to the ion conduction through the PEO matrix, the filler forms additional low-energy ion conducting channels at its interface with the matrix. The pendent POSS nanocages of GO-graft-PEG6k-block-P(MAPOSS) might probably increase the free volume at the interface with the matrix that is associated with higher chain and ion mobility, thus further enhancing the ion conductivity as compared with GO and GO-graft-PEG6k. The faster ion dynamics in 1.0 wt % GO-graft-PEG6k-block-P(MAPOSS) NSPEs has also been verified by the dielectric relaxation studies. Thus, integration of both the PEG and POSS nanocages into GO-grafted brush-like architecture offers a new tool for tuning the lithium ion conductivity for potential Li ion battery applications.

Dielectric Relaxation Studies on the Hydration Dynamics of Ionic, Non-Ionic and Zwitterionic Surfactants in Aqueous Acetate Buffer Solution

Dielectric relaxation studies of acetate buffer solutions of Sodium Dodecyl Sulphate (SDS- anionic), Cetyl Trimethyl Ammonium Bromide (CTAB- cationic), Tween 80 (TW-80-non-ionic), Betaine Anhydrous (BA- zwitterionic) surfactants have been examined in the frequency region between 1GHz and 25GHz for various concentrations of surfactants at the temperatures of 283, 288, 293 and 298K using time domain dielectric spectroscopy. The obtained corrected loss spectra of all the amphiphiles except betaine anhydrous in acetate buffer solution depicted peaks near 1-2GHz and 15GHz, respectively. For betaine anhydrous, expected peak was not observed in the 1-2GHz frequency region. The peak ascertained near 15GHz, and another peak about 1-2GHz was accorded to free water relaxation and bound water reorientation of the surfactant micelles, and has acquired the reliance of temperature with concentration in detail. Single Debye and Cole-Cole function was employed to compute the relaxation times of free water and bound water, respectively. The Arrhenius plot was used to calculate the enthalpy and entropy for the micelle forming surfactants.

Ion Transport and Dielectric Studies on [PEO:TiO2]:NH4SCN Nanocomposite Polymer Electrolytes

AbstractAn improvement in ion transport behavior and dielectric properties of polyethylene oxide based polymer electrolytes have been investigated upon the dispersal of TiO2 nanoparticles. TiO2 nanoparticle is synthesized with the help of well‐known sol–gel technique. The different compositions of polymer electrolyte systems are prepared by the solution cast technique. Nanocomposite polymer electrolytes (NCPEs) films are synthesized by loading of nanoTiO2 particle in a pristine polymer electrolyte matrix. The structural and morphological behaviors of nanocomposite polymer electrolytes (NCPEs) have been subsequently characterized by XRD and SEM studies. The ionic behavior of synthesized NCPEs is ascertained by Wagner's polarization technique. AC and DC conductivity of polymer electrolyte films have been carried out using impedance spectroscopic techniques. Dielectric relaxation studies of polymer electrolytes are examined using impedance spectroscopic data. The conductivity relaxation mechanism of NCPEs has been concluded with the help of modulus formalism. DC conductivity of best ion‐conducting NCPEs at room temperature has been found to σ = 2.5 × 10−5 S cm−1. The electrode polarization effect has completely vanished in the dielectric and modulus formalism and the conductivity scaling data show a single master curve observed in ion dynamics. The change in ionic conductivity with frequency and temperature is studied by impedance spectroscopic investigations. The effect of salt on dielectric parameters of NCPEs is also extracted from impedance spectroscopic data to explore underlying ion dynamics.

Valeramide and Halo-phenol in a Non-polar Liquid: DFT Based Characterization and Reactivity, Non-covalent Interaction, and Dielectric Relaxation Studies

Valeramide and halogenated phenol in solvent benzene have been studied using DFT. Dielectric relaxation studies have also been undertaken. The wave functional characteristics like reduced density gradient (RDG), electron localization function (ELF), localized orbital locator (LOL) are also evaluated. It has been found that the computed FMO energies accurately depict the characteristics of electron excitation which provide an explanation for the charge transfer. MEP analysis is done to identify electrophilic and nucleophilic sites. The theoretical analysis of the UV-Visible spectrum using the TD-DFT method in solution and the computational investigation of spectroscopic wavenumbers was also carried out (IR, Raman). Thermodynamic properties of title compound at different temperatures was carried out. Various dielectric parameters, like the dielectric constant the dielectric loss at microwave frequency, the static dielectric constant ε0 and the dielectric constant ε∞ at optical frequency, were measured across five distinct molar ratios (i.e. 1:3, 1:2, 1:1, 2:1 and 3:1). While the relaxation time τ2 for group rotation is utilized to identify the steric interaction of the proton donor, Higasi’s single-frequency equation is proven to measure multiple relaxation time τ1 to determine the intensity of hydrogen bonding. At a 1:1 (molar ratio) , the values of relaxation time were found to be high. Molecular docking was done in a supplementary effort to support intermolecular interactions.

Dielectric relaxation studies of poly(ethylene oxide) with the addition of salt or nanofiller

AbstractPoly(ethylene oxide) (PEO)–lithium perchlorate (LiClO4) serves as the classical model of polymer–salt systems with good polymer–salt molecular interaction at low salt concentration, whereas titanium dioxide (TiO2) without any surface treatment when added to PEO serves as a classical model of polymer–filler systems with weak polymer–filler molecular interaction. The correlation of molecular interactions of polymer–salt or polymer–filler with thermal properties of the systems, which govern the formation of morphologies of the systems, was attempted in a previous study. Hence, this work focuses on the correlation of morphologies and dielectric relaxation properties of PEO with the addition of LiClO4 or TiO2 investigated using polarized optical microscopy and electrochemical impedance spectroscopy over the frequency range from 50 Hz to 1 MHz at 25 °C. The effects of the addition of LiClO4 or TiO2 on the dynamics and relaxations of the polymer chain of PEO are discussed empirically following the fluctuation–dissipation effects from the common electrochemical terms and equivalent circuit model. The PEO–LiClO4 system seems to be one of the promising polymer electrolytes for application in lithium rechargeable batteries where the charged entities may arise from the interaction of salt with the ether oxygen of PEO in the amorphous region. Meanwhile, the PEO–TiO2 system may be analogous to a polar polymer with longitudinal dipoles along the PEO backbone, ethylene oxide monomers (from PEO) of which may represent the molecular dipole or charged entity. The findings show that the transport of charged entities in the PEO systems after the addition of LiClO4 or TiO2 is dominated by short‐range motion at room temperature. © 2022 Society of Industrial Chemistry.

Dielectric relaxation studies in WO3 mixed lead vanadate glasses

Dielectric relaxation studies in WO3 mixed lead vanadate glasses

Dielectric relaxation, dipole moment, electronic characterization and non-covalent interaction behavior of valeramide and halo-phenol in non-polar liquid: A density functional theory-based approach

In the present work, DFT has been used to explore the structural, electronic, charge transfer and molecular interactions between valeramide and halogenated phenol in solvent benzene and Dielectric relaxation studies have also been used. The optimized geometrical parameters, wavefunctional characteristics like a reduced density gradient, chemical bonds and the electron localization function are reported. It has been discovered that the HOMO and LUMO computed energies accurately depict the characteristics of electron excitation. MEP analysis is used to identify electrophilic and nucleophilic sites. The analysis of the UV–visible spectrum using the TD-DFT method with solutions and the computational investigation of spectroscopic wavenumbers (IR, Raman). The study of natural bond orbitals is carried out to provide an explanation for the charge transfer and stabilization energy resulting from current intra- or intermolecular interactions. Dipole moments of the pure liquids are calculated from the dielectric data using Higasi’s method and compared with the literature results. Various dielectric parameters are given, including the dielectric constant ε′, the dielectric loss ε′′ at microwave frequency, the static dielectric constant ε0 and the dielectric constant ε∞ at optical frequency. The different parameters of dielectric, relaxation time (τ0) and the dipole moment (μ) has been evaluated using the single-frequency concentration Higasi’s method. The fact that the relaxation time of the 1:1 M ratio are greater than those of other higher molar ratios (i.e. 3:1, 2:1, 1:2, 1:3) confirms the presence of a 1:1 complex structure between the studied systems, as well as a complex formation between the free hydroxyl group of phenols and the carbonyl group of amide.

Dielectric, XPS, and ferromagnetic relaxation studies of Ho-substituted polycrystalline magnetic oxide materials

The impact of holmium (Ho) ions on lithium-rich spinel ferrites is studied through magnetic, morphological, and electrical transport properties. The X-ray photoelectron spectroscopy (XPS) analysis indicated the existence of all metal ions in the required valence state. Transmission electron microscopy (TEM) analysis exhibited nano-crystalline (∼50 nm) structures of these ferrites. The electrical resistivity measurements showed the higher resistivity values of the synthesized samples. The resistivity increased from 2.4 × 108 to 2.1 × 1010 Ω-cm with Ho inclusion, indicated an inverse relation with the size of grains. The Curie temperature (Tc) observed to decrease from 848 to 806 K with the incorporation of Ho3+ions. The activation energy (ΔEa) noted to vary between 0.21 and 0.23 eV. The drift mobility (μd) study revealed a decrease from 1.86x10−12to 6.14x10−14cm2V−1s−1by increasing Ho amount up to x = 0.06. A reduction in thermoelectric power (S) from -143 to -95 μ.V/K by increase in Ho concentration confirmed the Fe replacement by Ho on octahedral B-sites. The ferromagnetic resonance (FMR) investigations indicated a drop in FMR line-broadening (ΔH) from 2491 to 2000 Oe by the increase of Ho concentration, making it beneficial to reduce microwave losses. A non-linear variation in the resonance field (Hres) with the substitution of Ho was observed between 7359 to 7785 Oe.