Imaginary Part Of Modulus Research Articles

Investigation of Electrical and Dielectrically Properties of a Novel Structure of PANI-PPy--GO-MWCNTs Composite/MnO2/Fe3O4/n-Si Structure

We investigated here the electrical properties of the novel structure of PANI-PPy-GO-MWCNTs composite/MnO2/Fe3O4/n-Si. This structure has not been addressed in literature before, the manufacture of this novel structure is carried out using a simple technique. So, we introduce here a novel structure with a simple method of manufacture. The imaginary part of modulus M″ has two behaviors, the first behavior at high and low frequency and the second behavior at mid frequency, so the M″ gives two contrarian behaviors, The M″ is a strong function of frequency and we can change the behavior of M″ by change of frequencies. The Col—Col diagram of modulus has ideal figures at some voltages including two semicircles of grains and grain boundaries. The imaginary part of impedance Z″ vs frequency creates peaks, the peaks shift toward the low frequencies. The novel here the Z″ has positive and negative values, despite the Z″ should have negative values only. The real part of impedance Z″ keeps on without change at high frequencies and splits for all temperatures at low and mid frequencies. Some electrical properties such as barrier height ɸb,Wd the width of the depletion layer, Nss the density of states, and acceptor carrier concentration Na were obtained by C—V2. All these parameters were strong functions of frequency.

Valence band spectra and doping based alterations in band gap and electric modulus of Nd2NiMnO6

Here in this paper, extending our earlier study, we have investigated the electrical properties of Sr doped Nd2NiMnO6 through the study of electric modulus. Nd2NiMnO6 has been doped with Sr by replacing Nd and the doping has not induced any new phase as all the samples of Nd2-xSrxNiMnO6 (x = 0.0, 0.1, 0.3) show monoclinic phase. Valence band spectra have been determined through x-ray photoemission spectroscopy and the absence of spectral density at Fermi energy EF for all the three samples indicates the insulating behavior with the sample having doping concentration x = 0.1 being the highly insulating of all the samples. Modulus study has been carried out in order to investigate more about the electrical properties by studying the dependence of real and imaginary part of modulus on frequency and temperature. The variation of real and imaginary part of electric modulus with the concentration of dopant has also been observed. The modulus study reveals the relaxation phenomenon in all the three samples. Further, we have determined the band gap of three samples through UV-Visible spectroscopy and the variation in the value of band gap with changing concentration of dopant Sr is in accordance with the conductivity plots already discussed in our earlier studies.

Gd3+ substitution effects, electrical and AC impedance characterizations of Gd/Cr co-doped SrBi4Ti4O15 Aurivillius-phase ceramics

Gd/Cr co-doped SrBi4Ti4O15 (Sr1-xGdxBi4Ti4O15 + 0.2 wt% Cr2O3, x = 0∼0.08) Aurivillius-phase ceramics were prepared by the traditional solid-state reaction process, the influences of Gd3+ doping concentration (x) on the structures and electrical properties of SrBi4Ti4O15 were investigated, as well as the AC impedance characterizations of the ceramics were analyzed. The incorporation of Gd2O3 and Cr2O3 into SrBi4Ti4O15 induced the lattice distortion of its orthorhombic structure. The donor substitution of Gd3+ for Sr2+ at A-site improved the Curie temperature (TC) and decrease the temperature coefficient of dielectric constant (TKε), as well as change the relaxation activation energy (Earel) of SrBi4Ti4O15 through the lattice distortion caused. Between 425 °C and 700 °C, the DC conduction behaviors of the ceramics was found with a transition from the mixed conduction mechanism involved in both the single-ionized oxygen vacancy and the double-ionized one to the single mode dominated by the latter one. Above TC, the imaginary part of modulus (M″) gradually shifts towards higher frequencies with increasing temperature, indicating the emergence of a new dielectric relaxation mode related to the phase transition process of the ceramics. Owing to the co-doping effects of Gd3+ and Cr3+, the optimized composition with x = 0.03 achieved excellent electrical properties (TC = 550 °C and d33 = 30 pC/N) and good thermal stability (TKε = 4.19 × 10−3/°C between RT and 500 °C, and the lose in d33 is only 3.3% after being annealed at 500 °C for 4 h), which make it promising for stable applications below 500 °C in the high-temperature piezoelectric devices.

Structural and dielectric properties of Bi2O3 nanoparticles synthesized at different temperatures

In the present work, Bi2O3 nanoparticles were synthesized by auto combustion method (auto chemical method). X-ray diffraction pattern confirmed that α- Bi2O3 nanoparticles were synthesized and possessed Monoclinic Crystal structure (P21/c space group). Dielectric properties possess significant value with low loss factor. Ac conductivity is increases due to the de-trapping of charge carriers different trapping centers. Real part of Modulus (Mʹ) rises and reaches a maximum constant value at higher frequencies for both samples. This type of behavior would support conduction phenomena. There is an asymmetric broadening of the peak in imaginary part of modulus (Mʹʹ) at 700 ˚C, which indicates that it is non-Debye type relaxation.

Natural mass hierarchy among three heavy Majorana neutrinos for resonant leptogenesis under modular A4 symmetry

It is clear that matter is dominant in the Universe compared to antimatter. We call this problem baryon asymmetry. The baryon asymmetry is experimentally determined by both cosmic microwave background and big bang nucleosynthesis measurements. To resolve the baryon number asymmetry of the Universe as well as neutrino oscillations, we study a radiative seesaw model in a modular A4 symmetry. Degenerate heavy Majorana neutrino masses can be naturally realized in an appropriate assignments under modular A4 with large imaginary part of modulus τ, and it can induce measured baryon number via resonant leptogenesis that is valid in around TeV scale energy theory. We also find that the dominant contribution to the CP asymmetry arises from Re[τ] through our numerical analysis satisfying the neutrino oscillation data.

Impedance and Electric Modulus Spectroscopy of Polycrystalline La0.5Sr0.5Bi0.2Co0.4Fe0.4O3–d Cathode Ceramic for Intermediate Temperature SOFCs

In the present research work, La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d cathode ceramic powder is synthesized through cost-effective flash pyrolysis process and further conventional heat treatment for sintering for IT-SOFCs. The crystal structure, unit cell parameters and bond length are determined by using the Rietveld refinement program. The XRD result indicates existence of a pure single phase with R C space group symmetry detected from the sample which has been sintered at 700 ℃. SEM images of fracture surface of sample sintered at 700 ℃ showed a high porosity and nano grain sizes (50-100 nm). Impedance and electric modulus spectroscopic methods are used to identify the relaxation phenomena in La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d ceramic over a broad range of temperature and frequency. A single relaxation peak is observed in the imaginary part of impedance and electric modulus spectra, which could be due to the contribution of grain boundary of La 0.5 Sr 0.5 Bi 0.2 Co 0 . 4 Fe 0.4 O 3– d ceramic. The imaginary part of modulus ( ) spectra is analyzed with help of non-exponential decay function or Kohlrausch–Williams–Watts (KWW) parameter ( β ). In the combined plot of the imaginary part of impedance and electric modulus spectra at 210 ℃, only a single peak of and is observed at the same frequency which indicates that the conduction process is a long-range motion of the charge carriers. The frequency-dependent conductivity is followed by the Jonscher’s double power law in the temperature range 30-210 ℃.

Ionic conductivity and relaxation studies in PVDF-HFP:PMMA-based gel polymer blend electrolyte with LiClO4salt

Poly(vinylidene fluoride-hexafluropropylene) (PVDF-HFP) and poly(methyl methacrylate) (PMMA)-based gel polymer electrolytes (GPEs) comprising propylene carbonate and diethyl carbonate mixed plasticizer with variation of lithium perchlorate (LiClO4) salt concentrations have been prepared using a solvent casting technique. Structural characterization has been carried out using XRD wherein diffraction pattern reveals the amorphous nature of sample up to 7.5[Formula: see text]wt.% salt and complexation of polymers and salt have been studied by FTIR analysis. Surface morphology of the samples has been studied using scanning electron microscope. Electrochemical impedance spectroscopy in the temperature range 303–363[Formula: see text]K has been carried out for electrical conductivity. The maximum room temperature conductivity of 2.83[Formula: see text][Formula: see text]S cm[Formula: see text] has been observed for the GPE incorporating 7.5[Formula: see text]wt.% LiClO4. The temperature dependence of ionic conductivity obeys the Arrhenius relation. The increase in ionic conductivity with change in temperatures and salt content is observed. Transport number measurement is carried out by Wagner’s DC polarization method. Loss tangent (tan [Formula: see text]) and imaginary part of modulus ([Formula: see text]) corresponding to dielectric relaxation and conductivity relaxation respectively show faster relaxation process with increasing salt content up to optimum value of 7.5[Formula: see text]wt.% LiClO4. The modulus ([Formula: see text]) shows that the conductivity relaxation is of non-Debye type (broader than Debye peak).

Influence of Swift Heavy O<sup>7+</sup> Ion Irradiation on Conductivity and Relaxation Dynamics of Two Different Blends of PVA:PEO:LiCF<sub>3</sub>SO<sub>3</sub>:EC System

In the present work, the variation in conductivity (σdc) and relaxation properties of two different blends i.e. Blend-1: [PVA(47.5):PEO(47.5):(LiCF3SO3)5:(EC)8] and Blend-2: [PVA(47):PEO(47):(LiCF3SO3)5:(EC)6] of PVA:PEO:LiCF3SO3:EC system, with respect to various fluences of swift heavy O7+ ion radiations ranging from 1x1011 to 3x1012 ions/cm2, is investigated in detail. Here, (i) the behavior of relaxation time (τ) calculated from M” vs. log f curves and (ii) the scaling of imaginary part of modulus (M”), is studied thoroughly for various fluences. The investigation thus, provides an insight regarding the effect of O7+ ion radiations on the relaxation dynamics of both the blends.

Alternating current characterization of nano-Pt(II) octaethylporphyrin (PtOEP) thin film as a new organic semiconductor

Alternating current (AC) conductivity and dielectric properties of thermally evaporated Au/PtOEP/Au thin films are investigated each as a function of temperature (303 K–473 K) and frequency (50 Hz–5 MHz). The frequency dependence of AC conductivity follows the Jonscher universal dynamic law. The AC-activation energies are determined at different frequencies. It is found that the correlated barrier hopping (CBH) model is the dominant conduction mechanism. The variation of the frequency exponent s with temperature is analyzed in terms of the CBH model. Coulombic barrier height Wm, hopping distance Rω, and the density of localized states N(EF) are valued at different frequencies. Dielectric constant ε1(ω,T) and dielectric loss ε2(ω,T) are discussed in terms of the dielectric polarization process. The dielectric modulus shows the non-Debye relaxation in the material. The extracted relaxation time by using the imaginary part of modulus (M″) is found to follow the Arrhenius law.

Electrical Behavior of Probertite by Dielectric Spectroscopy

AbstractIn this work of the material investigation, electrical parameters, which are real part and imaginary part of modulus, dielectric constant, dissipation factor, and conductivity, in the bulk pellet of probertite sample is presented. Electrical properties were investigated via temperature and frequency dependent dielectric spectroscopy. Real and imaginary part of dielectric parameter properties of the probertite were measured at frequencies from 100 to 15M Hz in the temperature range of 25 to 150 °C. Temperature dependence of the real part of the dielectric constant suggests that these compounds exhibit strong electromagnetic absorption and broadband electrical behavior.

Impedance Analysis of Gellan Gum - Poly(vinyl pyrrolidone) Membranes

This paper presents the impedance study of low acyl gellan gum/poly(vinyl pyrrolidone) blend as a host matrix for ion conduction. Low salt content of lithium perchlorate was added into the blend polymer host and the membranes were prepared by the means of solution casting method. The temperature-conductivity of the investigated samples follows the Vogel-Tamann-Fulcher rule. The occurrence of electrode polarization was explained by the combination of the dielectric loss, tangent loss and imaginary part of conductivity. The relaxation time for dipole orientation and ionic conductivity were calculated from tangent loss and imaginary part of modulus.

Dielectric relaxation studies in soft — matter like nanocomposite polymer electrolyte PPG4 — AgCF3SO3: MgO

We have designed a new class of soft — matter like nanocomposite polymer electrolyte with the incorporation of MgO nanoparticles into poly (propylene glycol) (PPG) 4000 — AgCF3SO3 and examined the segmental dynamics and structural relaxation processes in detail by the impedance data as a function of frequency at various temperatures. The ionic conductivity value of 3 wt% MgO nanoparticles embedded composite revealed the maximum of 5.2 × 10−4 Scm−1 at 298 K. The frequency — dependence of mobility and structural relaxations has been discussed in terms of real and imaginary parts of modulus and dielectric spectra which suggested the presence of two types of relaxation times appearing within the electrolyte: the low frequency side revealed the dispersion contributing the α-relaxation (dipole — segmental motion) and an almost plateau — like trend contributing β-relaxation that is visible at the high frequency end. The frequency response of the modulus plot showed an asymmetrical nature rather than the ideal Debye type of behaviour.

AC conductivity and impedance measurements in alkali boro-tellurite glasses

AC conductivity and impedance measurements were carried out for an alkali boro-tellurite glass system having composition 60B 2O 3-10TeO 2-5TiO 2-25R 2O (where R — Li, Na and K). The impedance plots ( Z″ ( ω) vs. Z′ ( ω)) for all glass samples were recorded and found to exhibit good single well-shaped semi circles over the studied temperature range. Frequency dependence of the imaginary part of impedance Z″( ω) and the imaginary part of modulus ( M″) for all glass samples at different temperatures was also investigated. The conductivity isotherms show a transition from independent DC region to dispersive region where the conductivity continuously increases with increasing frequency. For low frequency region, conductivity values ( σ ac) at RT are relatively low in the order of 10 − 8 to 10 − 9 (Ohm-cm) − 1 . However, there is an increase in conductivity with temperature for all glass samples showing conductivities at 300 °C ( σ 300) in the range 10 − 6 to 10 − 5.5 (Ohm-cm) − 1 . In the high frequency region, conductivity is enhanced by one order of magnitude (10 − 5 (Ohm-cm) − 1 ) as temperature is increased. Power law parameter ( s) is determined for all the glass samples at various temperatures and lowest ‘ s’ values are found to be for lithium-containing glasses. An excellent time-temperature superposition in the imaginary part of the dielectric modulus ( M″) confirms that the dynamical process is temperature independent and is also indicative of a common ion transport mechanism.

Synthesis, electrical and electromechanical properties of a tungsten-bronze ceramic oxide: Pb 0.68K 0.64Nb 2O 6

A tungsten-bronze ceramic oxide, Pb 0.68K 0.64Nb 2O 6, has been prepared by a standard solid-state reaction technique. Compound formation and phase identification has been confirmed by X-ray diffraction (XRD) studies. The dielectric permittivity and the loss tangent of the sample have been measured in a frequency range 45 Hz–5 MHz and a temperature range 35–590 °C. Electrical properties of the material were studied using an impedance spectroscopic technique. Detailed analysis of the impedance spectrum suggested that the electrical properties of the material are strongly temperature dependent. The Nyquist plots clearly showed the presence of bulk and grain boundary effect in the compound. The imaginary part of modulus at different temperatures shows a relaxation peak and its position shifts to higher frequency with increase in temperature. This suggests a temperature-dependent relaxation. The frequency dependent ac conductivity at different temperatures indicated that the conduction process is thermally activated process.

Viscoelasticity of Rubber

Abstract A theory has been obtained for the viscoelastic behavior of rubber in the frequency range above that at which creep is important and below that at which it behaves like a hard solid. The rubber chains are treated as springs in a viscous medium, and a general expression is obtained for the contribution to modulus of a single section of chain as a function of its length and terminations. A statistical estimate is made of the number of chain segments having given length and terminations. A modulus function is found for the group of chains with each kind of termination, and these are added in the proper amounts to give the form of the modulus vs. frequency curve for any amount of cross-linking. Measurements of shear modulus were made on one apparatus at frequencies between 0.0125 and 750 cps. Agreement is good if a pure viscosity is added to the theory. However, at low frequencies the imaginary part of modulus does not decrease as much as predicted.