High Value Of Dielectric Constant Research Articles

Structural characterization, dielectric properties and electrical conductivity of ZnO nanoparticles synthesized by co-precipitation route

The fabrication and characterization of zinc oxide (ZnO) nanoparticles (NPs) synthesized by a simple co-precipitation technique is reported in this work. The structural, morphological and dielectrical properties of the as-synthesized nanostructures were investigated. X-ray diffraction (XRD) pattern revealed that the obtained ZnO NPs are polycrystalline and crystallized in a single phase wurtzite with an average particle size of around 15 nm. The same size was found from scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR- TEM). Dielectric measurements of ZnO NPs at different temperatures were carried out by impedance spectroscopy with respect to frequency. The high dielectric constant values of ZnO NPs at low frequencies range were observed owing to field rotation polarization and space charge. Both dielectric constant and dielectric loss of ZnO NPs showed decreasing behavior with frequency. This may be explained in terms of formation of boundaries between the nanoparticles of ZnO. The ac conductivity (σac) was found to be improved with temperature for T between 290 K and 409 K owing to the presence of defect centers and charge carriers.

Corrigendum

Chemical Biology & Drug DesignVolume 97, Issue 6 p. 1210-1210 CORRIGENDUMFree Access Corrigendum This article corrects the following: The effect of multiple simulation parameters on MM/PBSA performance for binding affinity prediction of CB1 cannabinoid receptor agonists and antagonists Jason S. E. Loo, Amelia Y. Y. Yong, Yen Nee Yong, Volume 96Issue 5Chemical Biology & Drug Design pages: 1244-1254 First Published online: June 25, 2020 First published: 10 May 2021 https://doi.org/10.1111/cbdd.13844AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat The effect of multiple simulation parameters on MM/PBSA performance for binding affinity prediction of CB1 cannabinoid receptor agonists and antagonists. Chem Biol Drug Des. 2020;96:1244–1254. Jason S. E. Loo, Amelia Y. Y. Yong, Yen Nee Yong. The Abstract was incorrectly amended during proofing. The corrected Abstract is reproduced below. Both the inactive- and active-state CB1 receptor crystal structures have now been solved, allowing their application in various structure-based drug design methods. One potential method utilizing these crystal structures is the Molecular Mechanics/Poisson–Boltzmann Surface Area (MM/PBSA) method of predicting relative binding free energies. However, MM/PBSA performance is sensitive to various simulation parameters and often requires optimization for the system of interest. In this study, we evaluated the effects of various simulation parameters, namely simulation length, choice of dielectric constant, inclusion of explicit water molecules, and inclusion of entropy, on the ability of MM/PBSA to predict the experimental binding free energies of a set of known CB1 agonists and antagonists. MM/PBSA produced r values ranging from 0.410 to 0.688 for the CB1 agonists and from 0.420 to 0.678 for the CB1 antagonists depending on the simulation parameters, which were modestly better than correlations obtained using docking scores. Using fewer replicates with a longer simulation length and a higher solute dielectric constant value had the largest positive effect on performance. Including explicit water molecules at the protein–ligand interface had a minor positive effect on performance at higher dielectric constant values, while the inclusion of entropy had a detrimental effect across most of the dataset. REFERENCE Loo, JSE, Yong, AYY, & Yong, YN (2020). The effect of multiple simulation parameters on MM/PBSA performance for binding affinity prediction of CB1 cannabinoid receptor agonists and antagonists. Chem Biol Drug Des., 96: 1244– 1254. https://doi.org/10.1111/cbdd.13733Wiley Online LibraryCASPubMedWeb of Science®Google Scholar Volume97, Issue6June 2021Pages 1210-1210 ReferencesRelatedInformation

Computational assessment and experimental study of optical and thermoelectric properties of rutile SnO2 semiconductor

Throughout this research, the optical and thermoelectric properties of rutile SnO2 are investigated using the ab-initio method and the experimental measurements. Both phonon dispersion curve and dynamical stability of rutile SnO2 have been investigated. The high static value of dielectric constant (4.2LDA and 5.1GGA), and refractive index (2.1LDA and 3.01GGA) are determined. Thermoelectric properties of pure SnO2 such as Seebeck coefficient, electrical conductivity, thermal conductivity, and the figure of merit are calculated as a result of temperature within 300–700 K range. The obtained values show that the pure rutile SnO2 can be a good candidate for a thermoelectric application. The obtained results of the current investigation demonstrate a potential application of rutile SnO2 in many thermoelectric, optoelectronics, and photonic applications. Deposited by spray pyrolysis method, a (110) -oriented tetragonal crystal structure of SnO2 thin layer is confirmed by X-ray patterns. SnO2 thin layer demonstrates a high transparency >80% within IR range with an optical bandgap of 3.5 eV. Furthermore photoluminescence analysis reveals the blue (452 nm) emission and SEM, AFM observations confirm the nanostructure aspect of such layers with an average grain size of 100 nm.

Impedance Spectroscopic Study of Nickel Sulfide Nanostructures Deposited by Aerosol Assisted Chemical Vapor Deposition Technique.

This research aims to synthesize the Bis(di-isobutyldithiophosphinato) nickel (II) complex [Ni(iBu2PS2)] to be employed as a substrate for the deposition of nickel sulfide nanostructures, and to investigate its dielectric and impedance characteristics for applications in the electronic industry. Various analytical tools including elemental analysis, mass spectrometry, IR, and TGA were also used to further confirm the successful synthesis of the precursor. NiS nanostructures were grown on the glass substrates by employing an aerosol assisted chemical vapor deposition (AACVD) technique via successful decomposition of the synthesized complex under variable temperature conditions. XRD, SEM, TEM, and EDX methods were well applied to examine resultant nanostructures. Dielectric studies of NiS were carried out at room temperature within the 100 Hz to 5 MHz frequency range. Maxwell-Wagner model gave a complete explanation of the variation of dielectric properties along with frequency. The reason behind high dielectric constant values at low frequency was further endorsed by Koops phenomenological model. The efficient translational hopping and futile reorientation vibration caused the overdue exceptional drift of ac conductivity (σac) along with the rise in frequency. Two relaxation processes caused by grains and grain boundaries were identified from the fitting of a complex impedance plot with an equivalent circuit model (Rg Cg) (Rgb Qgb Cgb). Asymmetry and depression in the semicircle having center present lower than the impedance real axis gave solid justification of dielectric behavior that is non-Debye in nature.

Facile synthesis of efficient heterogeneous photocatalytic and highly dielectric Bi4BaTi4O15 ceramic with remarkable applicability in the degradation of rhodamine B dye

ABSTRACT Bi4BaTi4O15(BBTO), an Aurivillius oxide, which is a mixed metal bismuth–layered based oxide fabricated by chemical route, has shown highly efficient photocatalytic activity in degradation of organic dye besides possessing high dielectric constant. The obtained material was characterised by various techniques like Fourier Transform Infrared (FTIR), transmission electron microscope, Scanning Electron Microscopy-Energy Dispersive X-rays Spectroscopy (SEM-EDX) X-ray powder diffraction (XRD), Zetasizer Nano-ZS, Ultraviolet- differential reflectance spectroscopy (UV-DRS), Brunauer–Emmett–Teller, Atomic Force Microscopy (AFM) and X-ray photoelectron spectra for the phase identification, microstructural analysis, bandgap determination, elemental analysis and oxidation state of the material. XRD data confirm the presence of single-phase BBTO ceramic, corroborated by Le-Bail fitting analysis. A high dielectric constant value of 3.08 × 103 was obtained for the BBTO ceramic at 368 K. The material is stable in suspension form in solution and is a highly efficient photocatalyst. BBTO degraded 80% of RhB dye within 1 h of time period under UV light via major reactive species OH . radicals and O2 .- , generated during the photocatalytic reaction, which is proved to be following the first-order kinetics.

Microwave assisted synthesis of quantum dots like ZnS nanoparticles for optoelectronic applications: An effect of CTAB concentrations

Nanoparticles (NPs) of ZnS with different weights of CTAB (cetyltrimethylammonium bromide) have been successfully synthesized by microwave assisted co-precipitation method. The x-ray diffraction patterns exhibited cubic phase crystal structure with crystallite size of ~3 nm. The morphological studies of the grown samples have been investigated using Scanning electron microscopy (SEM). Diffused reflectance spectra were employed to calculate energy gaps for prepared samples using Kubelka-Munk theory, and the values were in the range of 3.59–3.64 eV. Raman spectra confirm the synthesis of ZnS nanoparticles at all CTAB contents and it contains two major Raman modes at ~264 and 346 cm−1 related to TO and LO modes which are shifted to lower wavenumbers indicates phonon confinement in the final products. The variations in the dielectric constant, ε' and dielectric loss were calculated. The values of ε' is higher in the low frequencies, whereas it is found almost stable between 1 MHz and 5 MHz and is increasing at higher frequencies. The dielectric study reveals that the samples possess high values of dielectric constant which are between 27 and 35 and low loss values. The electrical conductivity is noticed to be increased with increasing the frequency and also noticed to be varied with varying the CTAB content in ZnS. The synthesized low dimension NPs, high energy gap and dielectric constant and low loss values signifies that the prepared NPs are suitable for optoelectronics.

Conduction mechanisms and dielectric constant features of Fe doped ZnO nanocrystals

Fe doped ZnO nanocrystals (NCs) were synthesized from low cost sol gel method and the effect of iron content on their structural, transport and dielectric properties was studied. X-ray diffraction (XRD) measurements exhibit good crystalline quality of all the prepared NCs and a reduction of the crystallite size with Fe doping. Raman spectra confirmed the good crystallinity and revealed the formation of ferric phases for highly doped samples. Investigations of the impedance characteristics indicate that the samples are perfectly modulated from equivalent circuits using a constant phase element (CPE). Analysis of complex impedance and electrical modulus revealed a relaxation process dependent on temperature and of non-Debye type. Single activation energy was estimated for the electronic conduction, based on the Arrhenius plots. The conduction mechanism was governed from small polaron hopping in all the ZnO:Fe materials. The frequency dependence of the electric conductivity followed a simple Jonscher power behavior σac(ω)=σdc+Aωs (0.5≤ s ≤ 1), where the exponent s increased with temperature.The dielectric measurements, in both medium and high frequency regions, exhibited high dielectric constant values and low dielectric losses for all the samples, which could favor the use of Fe doped ZnO a as promising candidate for energy storage. The electrical modulus provides double relaxation times with low values. All the properties indicate that the ZnO:Fe material is suitable for device applications.

Polymer Composites with Improved Dielectric Properties: A Review

Materials exhibiting high dielectric constant (k) values find applications in capacitors, gate dielectrics, dielectric elastomers, energy storage device, while materials with low dielectric constant are required in electronic packaging and other such applications. Traditionally, high k value materials are associated with high dielectric losses, frequency-dependent dielectric behavior, and high loading of a filler. Materials with low k possess a low thermal conductivity. This creates the new challenges in the development of dielectric materials in both kinds of applications. Use of high dielectric constant filler materials increases the dielectric constant. In this study,the factors affecting the dielectric constant and the dielectric strength of polymer composites are explored. The present work aims to study the effect of various parameters affecting the dielectric properties of the materials. The factors selected in this study are the type of a polymer, type of a filler material used, size, shape, loading level and surface modification of a filler material, and method of preparation of the polymer composites. The study is focused on the dielectric enhancement of polymer nanocomposites used in the field of energy storage devices. The results show that the core-shell structured approach for high dielectric constant materials incorporated in a polymer matrix improves the dielectric constant of the polymer composite.

Electro‐optical performances of nanostructured SrTiOx films: The effect of plasma power, Ar/O2 ratio and annealing

AbstractThe present work evaluates the effects of plasma power and oxygen mixing ratios (OMRs) on structural, morphological, optical, and electrical properties of strontium titanate SrTiOx (STO) thin films. STO thin films were grown by magnetron sputtering, and later thermal annealing at 700°C for 1 h was applied to improve film properties. X‐ray diffraction analysis indicated that as‐deposited films have amorphous microstructure independent of deposition conditions. The films deposited at higher OMR values and later annealed also showed amorphous structure while the films deposited at lower OMR value and annealed have nanocrystallinity. In addition, all as‐deposited films were highly transparent (~80%–85%) in the visible spectrum and exhibited well‐defined main absorption edge, while the annealing improved transparency (90%) within the same spectrum. The calculated direct and indirect optical band gaps for films were in the range of 3.60‐4.30 eV as a function of deposition conditions. The refractive index of the films increased with OMRs and the postdeposition annealing. The frequency dependent capacitance measurements at 100 kHz were performed to obtain film dielectric constant values. High dielectric constant values reaching up to 100 were obtained. All STO samples exhibited more than 2.5 μC/cm2 charge storage capacity and low dielectric loss (less than 0.07 at 100 kHz). The leakage current density was relatively low (3 × 10−8Acm−2 at +0.8 V) indicating that STO films are promising for future dynamic random access memory applications.

Assessment of nanostructure, optical, dielectric and modulus response by Bi substitution in La1−xBixNi0.5Ti0.5O3 (x = 0.0–0.2) system

Perovskite-type oxides La1-xBixNi0.5Ti0.5O3 (x = 0.0, 0.2) were prepared by the sol–gel method employing the citric acid route and sintered at 820° C. The structural behavior analyzed by X-ray diffraction proved that all the samples have the same crystallographic structure (space group Pnma). The volume of the elemental lattice decreases with the rate of Bismuth substitution. Transmission electron microscopy (TEM) verified the nanosized grains. The FTIR spectra confirmed the formation of the orthorhombic perovskite structure. UV–Visible spectroscopy and photoluminescence were also applied to study the samples. The parameters of real and imaginary part of dielectric function (e′ and e″) and dielectric loss tangent (tg(δ)) show a strong frequency dependence. Those dependences explain a dispersive behavior at low frequencies and are outlined on the basis of the Maxwell–Wagner model and Koop theory. The compounds have very high dielectric constant values (e′ ≈ 103) that are useful in electronic devices. Electric modulus formalism was employed to investigate the relaxation dynamics of charge carriers. Moreover, a non-Debye type of relaxation was verified in our samples. The activation energy is specified from the analysis of the imaginary part of the electric modulus.

Structural, Optical and Dielectric Properties of Nd Doped NiO Thin Films Deposited with a Spray Pyrolysis Method

The effect of Nd doping (1, 3 and 5 wt%) on the structural, morphological, electrical and optical properties of NiO thin films deposited on glass substrates using nebulizer spray pyrolysis method are investigated. The X-ray diffraction study reveals cubic structure with an improvement in crystallinity upon the incorporation of Nd into NiO lattice. The films are > 50% transparent in the high wavelength region. The absorption spectra witnesses a sharp fall in the wavelength range, 300 nm < λ < 600 nm reflecting the semiconducting nature of these films. The optical direct (indirect) band gap values obtained using Tauc’s relation decrease from 3.67 eV (3.00 eV) for pure NiO to 3.38 eV (2.44 eV) for 3 wt% Nd:NiO. The linear refractive index (n) values estimated using different models are compared. Using the average linear refractive index along with optical direct band gap, the high-frequency and static dielectric constants; the linear and non-linear optical susceptibilities and non-linear refractive index are calculated. It is observed that all these quantities enhance with Nd doping whereas the static dielectric constant decreases with an increase in Nd content. The high frequency dielectric constant and static dielectric constant values are observed to vary between 5.08–5.45 and 51–32, respectively. The values of linear and non-linear optical susceptibilities and non-linear refractive index are found vary between 0.325–0.354, 1.90 × 10–12–2.67 × 10–12 esu and 3.17 × 10–11–4.31 × 10–11 esu, respectively.

An improved dielectric behavior of hydrothermally synthesized Ba0.4La0.6−yEuyTiO3 (y = 0.01–0.04) nanorods

Ba0.4La0.6−yEuyTiO3 (y = 0.01–0.04) nanorods were synthesized using simple hydrothermal technique. The mixed structure consisting of tetragonal and rhombohedral phases of the prepared nanorods was confirmed by X-ray diffraction patterns. The structural parameters were calculated and confirmed the tetragonal unit cells in the case of y = 0.01–0.04 samples. The surface morphology evidenced the nanorods like structures among all the samples using the FESEM and TEM studies. The y = 0.03 & 0.04 samples revealed the high dielectric constant values of 13,696 and 16,305 at 10 kHz indicating the applications in high storage capacitors. In addition, dielectric modulus and impedance spectroscopy analysis was done for having clear picture about the space charge polarization effect, relaxation dynamics and electrical conduction mechanism.

3% Fe2O3: Cr2O3- an excellent magneto-opto-electrically active nanomaterial

In this paper, pure and Fe2O3 (1–5 mol %) doped Cr2O3has been synthesized using a solid-state synthesis method. X-ray diffraction pattern of pure and Fe2O3: Cr2O3 has a similar crystallographic hexagonal phase with space group R-3c and lattice parameter, a = 5.002 A; c = 13.620 A and, a = 4.913 A; c = 13.469 A, respectively; average crystallite size being ∼29.46 nm. Fe3+ incorporation in Cr2O3 lattice leads to the increase in the particle size as Fe3+has larger ionic radii (∼0.67 A) than Cr3+ (∼0.64 A).Both XRD and EDX showed that Fe2O3: Cr2O3 nanoparticles exhibit no impurities phases, confirms the presence of Cr, Fe, and O materials. The Tauc’s plot showed a decrease in optical band gap from 3.10 to 2.95 eV for Fe content of 0 to 5 mol%, respectively. All samples revealed weak ferromagnetic behavior at room temperature. SEM analysis revealed an increase in particle size from16-38 nm. Electrically, at low frequencies, undoped and low concentration of Fe in Fe2O3: Cr2O3 shows high values of dielectric constant. Further, this value decreases continuously with the increase in frequency. The study revealed that 3% Fe2O3: Cr2O3 sample is excellent among all the doping concentrations (1–5 mol%) for magneto-optoelectronic device applications.

Effect of Ce-Mn Codoping on the Structural, Morphological and Electrical Properties of the BaTiO3 Based Ceramics

Undoped, Cerium (Ce) doped, Manganese (Mn) doped and Ce-Mn co-doped Barium Titanate (BaTiO3) with the general formula Ba1-xCexMnyTi1-yO3 (where x = 0.00, 0.01, 0.02, 0.03, y = 0.00; x = 0.00, y =0.01, 0.02, 0.03; and x = y = 0.01, 0.02,0.03) were synthesized by solid-state reaction method and sintered at 1200 C for 4 hr with an aim to study their structural and electrical properties. The grain size of the samples has been estimated using the Scanning Electron Microscopy (SEM). The X-ray Diffraction (XRD) analysis indicates that the structure of the Ce-doped and Ce-Mn co-doped BaTiO3 is cubic. However, the undoped BaTiO3 and Mn-doped BaTiO3 confirmed the tetragonal-cubic mixed phases. With the change of doping concentrations, the positions of different peaks shifted slightly. The lattice parameter varied irregularly with increasing doping concentration because of Mn's changeable valency. EDX spectra confirmed the presence of Ba, Ti, Ce, and Mn contents in the co-doped samples with stoichiometric ratio. Crystallinity is observed to be clearly increased when Ce-Mn is co-doped in BaTiO3. J-V characteristic curves indicate transition from conducting to semiconducting nature for the doped and co-doped samples with the increase in temperature. The dielectric constant of the samples increases up to 4500 with the doping concentration. The higher values of dielectric constant are observed for the 2% Mn-doped and 1% Ce-Mn co-doped samples compared to the other undoped samples. For the undoped and Mn-doped samples, constant dielectric values increase with temperature but decrease for the Ce-doped and Ce-Mn co-doped samples. It is inferred that co-doping of BaTiO3 with Ce and Mn would be beneficial and economical for its applications.

A-site substituted BiFeO3 ceramics: A study of structural and electrical properties

This work presents the influence of La3+ and Sr2+ substitution at Bi-site of BiFeO3 in the sense of phase, crystal structure and dielectric properties. The Bi1-x (Lax-y Sry)FeO3 (x = 0.1, y = 0, 0.05) ceramics with perovskite structure were synthesized by standard solid state route. Phase analysis exploiting X–ray diffraction (XRD) data disclosed formation of single phased trigonal structure with R3c space group. The calculated lattice parameters for Bi0.9La0.1FeO3 ceramic were a = b = 5.5771 Å and c = 13.8021 Å and Bi0.9La0.05Sr0.05FeO3 ceramic were a = b = 5.5844 Å and c = 13.8215 Å which witness trigonal structure. The calculated average crystallite size for Bi0.9La0.1FeO3 and Bi0.9La0.05Sr0.05FeO3 ceramics were 47.39 nm and 31.20 nm respectively. The dielectric analysis reveals that both the ceramics to exhibit good dielectric behavior with high dielectric constant and lower tangential loss value. In addition, Cole-Cole plot (M′ vs. M′′) and Nyquist plot (Z′ vs Z′′) exposed the non-Debye behavior of the ceramics and distribution of different relaxation phenomena in the ceramics.

In Ukrainian

In recent years, interest in studying the optical properties of metallic nanostructures has grown. This interest is primarily related to the possibility of practical application of such nanostructures in quantum optical computers, micro- and nanosensors. These applications are based on the fundamental optical effect of surface plasmon excitation. The consequence of this phenomenon is surface plasmon resonance (SPR) - an increase in the cross section of energy absorption by a metal nanoparticle as the frequency of incident light (laser radiation) approaches the SPR frequency of the nanoparticle. Plasmon structures are used to improve the efficiency of thin-film SC. In such structures, metal nanoparticles can primarily act as additional scattering elements for the long-wavelength component of sunlight illuminating SC. As a collective phenomenon, SPR can be described using kinetic approaches, ie using the Boltzmann kinetic equation for the conduction electrons of metal nanoparticles. In this work, the theory of SPR based on the kinetic equation for the conduction electrons of nanoparticles is constructed. to the well-known results derived from the Drude-Sommerfeld theory. Second, the kinetic method makes it possible to study metal nanoparticles with sizes larger or ptical conductivity tensor for spheroidal metal nanoparticles. It is shown that the effect of nanoparticle asymmetry on the ratio of the components of the optical conductivity tensor differs not only smaller than the average electron free path length. The developed theory is used to calculate the oquantitatively but also qualitatively in high-frequency and low-frequency surface scattering. It was found that in metal nanoparticles in a dielectric matrix, under SPR conditions, the full width of the SPR line in a spherical metal nanoparticle depends on both the radius of the particle and the frequency of the electromagnetic (laser) radiation exciting this SPR. It is shown that oscillations of the SPR line width with a change in the dielectric constant of the medium in which they are located can be observed in metal nanoparticles. The magnitude of these oscillations is greater the smaller the size of the nanoparticle and increases significantly with increase. As the radius of the spherical nanoparticle increases, the width of the SPR line decreases significantly and prevails around a certain constant value in media with a higher value of dielectric constant.

On the analogy between the restricted primitive model and capacitor circuits: Semi-empirical alternatives for over- and underscreening in the calculation of mean ionic activity coefficients

The analogy between the restricted primitive model and capacitor circuits, originally described decades ago for the Mean Spherical Approximation, is explored to demonstrate its transferability in linearized electrolyte theories. On this basis, we offer an explanation of why treating the salt diameter as a free adjustable parameter blurs differences between electrolyte theories in the calculation of mean ionic activity coefficients. Furthermore, a capacitor circuit analogy with an approximation of the Dressed Ion Theory is applied to develop a modified closest approach parameter “b” for the Pitzer-Debye-Hückel term. This modification is able to account for the qualitative effects of over- and underscreening in the calculation of mean ionic activity coefficients. This is achieved by defining “b” as a semi-empirical function that allows close resemblance with the multiple decay-length extension of the Debye-Hückel theory for high dielectric constant values and that lies close to recommended literature values of “b” for low dielectric constant values. Finally, as proof of principle, this modified semi-empirical Pitzer-Debye-Hückel term is implemented in the predictive COSMO-RS-ES model, an own reimplementation of the COSMO-RS theory developed for thermodynamic property calculations of electrolyte systems. It is shown that the modified semi-empirical Pitzer-Debye-Hückel term is an effective replacement for the recently published version of COSMO-RS-ES with explicit considerations for ion pairing. This reduces the modelling complexity by implicitly considering ion pairing and improves overall qualitative performance for the prediction of salt solubilities in mixed-solvent systems and even mean ionic activity coefficients in non-aqueous media.

Studies on structural and dielectric behaviour of PVA/PVP/SnO nanocomposites

The hybrid type of polymer nanocomposites based on Polyvinyl alcohol (PVA)/Poly(vinyl) pyrrolidone (PVP) with tin oxide (SnO) have been prepared by simple solution casting method. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) have been employed to elucidate the successful incorporation of SnO nanoparticles (NPs) in the PVA/PVP blend matrix. The increase in the crystalinity of the polymer nanocomposites (PNCs) by the addition of SnO nanoparticles concentration up to 3 wt. % of SnO has been confirmed by the PXRD analysis. The FTIR analysis implied the presence of hydrogen bonding interaction between SnO and the PVA/PVP blend matrix. SEM results revealed that SnO nanoparticles were uniformly dispersed in the PVA/PVP blend matrix. From the dielectric properties, it had been observed that 1 wt. % SnO added PNCs showed the high dielectric constant values at lower frequencies. The curves of argand plot at various temperatures were incomplete semicircles indicating the non-Debye behaviour. In modulus analysis, the height of the peak has been decreased by addition of SnO nanoparticles in the polymer matrix which confirms the non-Debye nature.

Novel rare earth yttrium doping effect on physical properties of PbS nanostructures: facile synthesis and characterization

The dielectric properties of pure and yttrium-doped PbS nanoparticles synthesized by the coprecipitation chemical synthesis route have been studied by several characterizations. X-ray diffraction patterns of samples were employed to estimate the crystallite sizes and intrinsic microstrains using Williamson–Hall (W–H) plot analysis. The crystallite size and intrinsic macrostrain values were evaluated in the range of 13.7–15.9 nm and 1.09 × 10–3–1.72 × 10–3, respectively, using W–H plots. The formation of nanoparticles, nanoflakes, sponge, and nanosheets were seen via scanning electron microscope (SEM). Energy dispersive spectroscopy (EDS) of 5.0 wt% confirms the Y: PbS sample elements' chemical composition and stoichiometry. The optical band gaps increase in the range of (0.93–1.17 eV) with an increase in the dislocation density. The higher values of dielectric constant (23.6–28.0), dielectric loss (37.6–176.8), loss tangent (2.7–8.6), and electrical conductivity [ 10.2 to ( 11.7) S/m] have been reported at the lower frequency. The highest electrical conductivity values were obtained in the range of [ 4.71 to ( 4.81) S/m] for as-prepared samples. The greater capacitance and impedance values were found at 3 kHz and decrease with increasing the frequency up to 10 MHz. The current–voltage characteristic curves of undoped and Y: PbS NPs were performed under biased voltage. The space charge current density was noticed in the range of (8.7 × 10–4–4.2 × 10–4 amp/cm2) at 1.0, 2.5, and 5.0 wt% of Y: PbS samples. The enhancement in the optical band gap and dielectric and electric properties on yttrium doping in PbS compared to pristine PbS NPs makes them suitable for optoelectronic applications.

Structural and electrical properties of double perovskite: (BaSr)FeMoO6

In this article, the structural, micro-structural, and temperature-frequency dependence of electrical characteristics of double perovskite (BaSr)FeMoO6 have been reported. The compound crystalizes in cubic symmetry with lattice parameter a = 7.9280 (2) Å, and V = 245.95 (Å)3. The micro-structural study suggests the uniform distribution of grains on its surface with small voids. The obtained high dielectric constant and low tangent loss value may be applicable for capacitor. In the impedance analysis we observed the behaviour of negative as well as positive temperature co-efficient of resistance. The study of the Nyquist plot suggests the existence of only grain effect. Based on both impedance and modulus spectroscopy, dielectric relaxation process is found to be of a non-Debye type. The frequency dependence of conductivity obeys the Jonscher's Power law which suggests the conduction phenomenon follows the non-overlaping small polaron tunnelling and correlated barrier hopping models. The calculated activation energy in the conduction process may be used in electron hoping. The comparative study of Zʹʹ and Mʹʹ with frequency suggests the existence of short range ordering of charge carriers. The leakage current study reveals that the conduction mechanism follows the space charge limited conduction phenomenon.