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The organic–inorganic hybrid materials provide promising opportunities for use in optoelectronics due to its wide range of physical characteristics and structural configuration. In this study, a slow evaporation method at room temperature was employed to synthesize the new-centrosymmetric (C6H9N2)2[SbBr4]Br compound. Analyzing by X ray diffraction of the studied compound conferred a 0D framework with monoclinic structure. The examination of SEM analysis allows us to raise the morphology and the good quality of the crystals. The EDX analysis was performed to ensure that all chemical elements were discovered and located in the relevant locations. An optical absorption measurement confirms the nature of the material and his band gap. The differential scanning calorimetry (DSC) was performed at temperatures ranging from 313 to 413 K, with two heating cycles to isolate the effects of surface humidity and phase transition temperatures. Besides, the impedance spectroscopy measurements conducted at 10−1 Hz to 5 MHz and 313–403 K are used to investigate the electrical and dielectric properties of the (C6H9N2)2[SbBr4]Br compound. An equivalent circuit model has been proposed to correlate the electrical properties. The frequency-dependent ac conductivity was studied and helped to find the proper conduction model. [ABSTRACT FROM AUTHOR]

This study examined the effect of mixed alkaline earth modifier fluoride on AC conductivity and dielectric properties in xBaF2–(50–x)CaF2–50B2O3 (x = 5–35 mol%) glass system. The impedance data showed a single-depressed semicircle with decreasing bulk resistance (Rb) with temperature. The change of σ AC implied a non-linear relationship with BaF2, which induced a blocking effect on the mobility of the charge carriers at x ≤ 20 mol%, indicating the Mixed Alkaline Earth Effect (MAEE). The abrupt increase at x = 25 mol% was associated with the expansion of the glass network due to the formation of Non-Bridging Oxygen (NBO). All glass samples followed the Overlapping Large-Polaron Tunneling (OLPT) model for the conduction mechanism. The change in ε′ more prominent in low-frequency regions, signifying that polarization was contributed mainly by the space charge polarization. Electrical modulus analysis revealed non-Debye type relaxation, indicating temperature- and composition-dependent dynamic ion processes. [ABSTRACT FROM AUTHOR]

LiCoO2 was synthesized by the conventional solid-state reaction. The X-ray diffraction indicates that the LiCoO2 sample crystallizes in a hexagonal system with an R-3 m space group. The optical properties were studied. The band gap energy was established and seems to be equal to 2.15 eV which confirms the semiconductor character of this compound. The study of the refractive index and the extinction coefficient proved the connection between the sample transparency and a low optical absorption loss. Furthermore, thermal analysis shows an exothermic peak at 335 K which was proven by studying the temperature dependence of the electrical properties. The equivalent circuit was chosen and the electrical conductivity was analyzed. The AC conductivity values (10−4 Ω−1 cm−1) confirm the semiconductor character and the ionic conduction type. The conduction mechanism was attributed to CBH for the first phase and NSPT for the second one. Additionally, electrical modulus investigation reveals the existence of grain boundary and grain effects. [ABSTRACT FROM AUTHOR]

In this work, Cu0.6Cd0.4Cr2O4 spinel oxide was synthesized by means of sol–gel auto-combustion route. The refined X-ray powder diffraction pattern confirmed the single-phase formation of the material, which crystallized in a cubic spinel structure with space group Fd-3 m. The alternating current conduction mechanism and modulus behavior of this sample were investigated over a broad frequency range (from 100 Hz to 1.6 MHz) for various temperatures ranging from 300 to 660 K. Two equivalent circuit models, R//C//CPE below 440 K and above this temperature R1//C1//CPE1 in series with R2//CPE2, were applied to fit the impedance data. The temperature dependence of the direct current conductivity could be described in terms of Arrhenius relation with four activation energies, 1.8 eV, 0.76 eV, 0.80 eV, and 0.98 eV, in regions I (T < 360 K); II (360–420 K); III (440–500 K); and IV (T > 500 K), respectively. The temperature and frequency dependence of AC conductivity was found to satisfy Jonscher's law (developed) at different temperatures. The variation of the exponent "s" with temperature strongly suggests that the conduction mechanism takes place by correlated barrier hopping (CBH) model in each region. A theoretical study of (AC) electrical conduction in this material has been interpreted using Elliot's theory, and Elliot's parameters are determined. For the modulus formalism, the extracted activation energies from the linear fit of ln(fp) as a function of 1000/T match well with those obtained from DC conductivity confirming that transport mechanisms were based on hopping phenomena. [ABSTRACT FROM AUTHOR]

Solution casting technique is tailored to synthesis the film samples of hydroxypropyl methylcellulose (HPMC)/poly vinylalcohol (PVA) blends embedded with various concentrations of copper oxide (CuO) nanoparticles (1–4%, wt%). The structural analysis by X-ray diffraction (XRD) confirmed the uniform dispersion of nano CuO into HPMC/PVA blends. The crystalline size as well as the percentage of crystallinity decreases with increasing concentration of CuO in all HPMC/PVA–CuO electrolyte systems. This reduced percentage of crystallinity greatly affects the conductivity property of the polymer electrolytes. The surface morphology and uniformity of phase formation of the samples were analyzed by scanning electron microscope (SEM). The samples were analyzed by using electrical impedance spectroscopy by LCR meter (ZM2376) with in the frequency range 50 Hz to 1 MHz. The dielectric constant decreases, while the AC electrical conductivity increases with increasing frequency. The plots of AC conductivity at high frequency region obey Jonscher Power Law. The frequency exponent (S) analysis for various temperature suggested that the correlated barrier hopping (CBH) model supports the ion transport mechanism at high temperatures for CuO (3 wt%) nanocomposite polymer electrolyte film. The presence of non-Debye type conductivity relaxation is observed in this reported polymer electrolytes by analyzing complex electrical modulus. The temperature dependent analysis of dielectric and AC conductivity properties increases with the increase in temperature. This may be due to the ion migration which is significantly improved by the addition of CuO nanoparticles. All estimated results of these nanocomposite polymer electrolytes are strongly convincing its use for the electrochemical cell device applications. [ABSTRACT FROM AUTHOR]

The physical properties of the sodium diphosphate ε Na4P2O7 ceramic were investigated by X-ray diffraction (XRD), morphology, dielectric, and electrical measurements. Rietveld refinements of X-ray diffraction (XRD) data show that the compound crystallizes in the orthorhombic structure belonging to the space group Pmmm. Not only were the AC conductivity of our compound carried out at different temperatures and frequencies, but also its electrical modulus was evaluated, as well as the dielectric relaxation. On the other hand, the behavior of frequency exponent s of AC conductivity as a function of temperature is reasonably well interpreted by the correlated barrier hopping (CBH). In terms of CBH model, the values of maximum barrier height, hopping distance, and density of localized states are determined and discussed. A correlation between electrical and structural properties was also studied. Besides, the present results provide insights into the exploitation of sodium diphosphate ε Na4P2O7 as a promising cathode material for application in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Bi1 − xFexNbO4 (x = 0.25, 0.50, and 0.75) samples were synthesized by the sol–gel method and its morphologic, structural, dielectric, and magnetic properties were studied. The structure was analyzed by X-ray diffraction and the morphology by scanning electron microscopy. The dielectric characterization that was performed using impedance spectroscopy, in the frequency range of 102–106 Hz, as a function of temperature, revealed that the dielectric constant and the dielectric losses increased with the iron content. The prepared materials presented relaxation processes, with the corresponding activation energies being calculated by fitting the experimental data to the Arrhenius model. The dependence of AC conductivity on frequency was found to satisfy Jonscher's universal power law at different temperatures. The conduction mechanisms are governed by two processes: correlated barrier hopping (CBH) and non-overlapping small polaron tunneling (NSPT). Magnetic susceptibility, for an applied magnetic field of 0.5 T, doubles when the iron concentration goes from 0.25 to 0.5 and doubles again when the iron concentration rises to 0.75. The increase in magnetization with the concentration of iron is also observed in the curves M vs. H at 7 K. The remaining magnetization and the coercive field do not exist for x = 0.25 (paramagnetic behavior); it is small for x = 0.5 and is already observed when x = 0.75. [ABSTRACT FROM AUTHOR]

Despite extensive research on CeO2 in diverse fields, studies on dielectric, conductivity behaviours due to intentional impurity-induced structural and microstructural changes are not well established. We show that structural changes arising due to Gd3+ in nano-CeO2 and the temperature affect the dielectric and conductivity characteristics. Highly crystalline nano-CeO2 and Ce1-xGdxO2-δ (GDC) (x = 0.02–0.1) are synthesized by self-sustained high-temperature synthesis. The dependence of conductivity on dopant concentration is examined over a wide-frequency (20 Hz to 10 MHz) and temperature (200–800 °C) range using a precision impedance analyzer. The conductivity reaches maximum at x = 0.06 for Ce1-xGdxO2-δ at 600 °C beyond which conductivity decreases. There is dependence of conductivity at lower frequencies, increases with increasing frequency, and gets saturated at higher frequencies. The optimum concentration (x = 0.06) found is the lowest for the Ce1-xGdxO2-δ system reported. The observed behaviour is discussed in terms of interaction between oxygen vacancies and defect associates. [ABSTRACT FROM AUTHOR]

Influence of grain size on electrical properties of nanocrystalline yttrium zirconate (Y2Zr2O7) prepared by hydrothermal method is reported. Appropriate heat treatment has yielded different particle sizes in the range from 2.9 to 30.3 nm. Structural phase analysis by x-ray diffraction, Rietveld analysis and Raman spectroscopy confirmed the cubic pyrochlore structure of YZO. Electrical conductivity and dielectric properties of YZO as a function of temperature for different grain sizes have been studied by impedance spectroscopy. The smallest sized (2.9 nm) YZO exhibited a well-resolved grain and grain boundary conduction because of high fraction of grain boundary volume. Arrhenius type of electrical conduction was shown in YZO, and the conduction species was found to be oxygen vacancies. Activation energy was increasing from 1.14 to 1.32 eV with decreasing grain size. AC conductivity was obeying Jonscher's power law behaviour and non-overlapping small polaron tunnelling model was employed to explain the electrical conduction. Clear dependence of increasing conductivity with increasing grain size was established in YZO. [ABSTRACT FROM AUTHOR]

In this work, Li2BaP2O7 doped 1% Eu3+ was prepared by a solid-state reaction method and characterized by X-ray diffraction technique, IR, and impedance spectroscopy. Rietveld refinement of the X-ray diffraction pattern suggests the formation of the single-phase desired compound with monoclinic structure at room temperature. Electrical properties were studied using complex impedance spectroscopy in the frequency range of 200 Hz–5 MHz and temperature range of 598–724 K. The temperature dependence of the bulk and grain boundaries' conductivity was found to obey the Arrhenius law with activation energies Eg = 0.79 eV and Egb = 1.85 eV respectively. Temperature dependence of the power law exponent s strongly suggests that tunneling of large polaron is the dominant transport process. The obtained results are compared with the undoped Li2BaP2O7 sample and correlated with structural analysis. Doping pyrophosphate compound by Eu3+ presents better conductivity and electrical properties. [ABSTRACT FROM AUTHOR]

Herein, we report the frequency-dependent AC conductivity of poly(aniline-co-m-nitroaniline)s which were synthesized by chemical oxidation of aniline and m-nitroaniline using ammonium persulfate as an oxidizing agent by in situ copolymerization approach. AC conductivity of the copolymers was recorded in the frequency range of 10−3 to 108 Hz. The imaginary and real part of permittivity of as-synthesized copolymers has been measured in the frequency limit of 10−2 to 107 Hz. The copolymer PA-co-m-NA20 has demonstrated very high value of permittivity than polyaniline at low frequency. At high frequency, the permittivity of the other PA-co-m-NA is almost unaltered. The SEM images manifest the unique morphology for each copolymer. The crystallinity of the copolymer samples has been studied XRD and the thermal stability of the polymers sample has been studied by differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

The new tetrabutylphosphonium tetrachloroantimonate (III) crystal has been grown by the solvent evaporation method. It crystallizes at room temperature in the monoclinic system (P21/n space group) with the following unit cell parameters: a = 10.535 Å (3), b = 18.796 Å (6), c = 12.743 Å (4), β = 94.39 (2)°, and Z = 4. The atomic arrangement of the title compound is composed by [(C4H9)4P]+ cations which form infinite chains along [100] direction. Two anionic groups connected by edges [Sb2Cl8]2− are intercalated in the octahedral cavities between six organic groups. The thermal analysis (DSC) studies indicate the presence of one order-disorder phase transition located at 338 K. Moreover, the electrical properties were performed in the frequency range 200 Hz-5 MHz and temperature interval from 313 to 353 K using impedance spectroscopy. Nyquist plots (−Z″ versus Z′) revealed the presence of two contributions at different temperatures associated with grain and grain boundaries. The equivalent circuit is formed by a series combination of two (Rg-C) and (Rgb-CPE) parallel. The frequency dependence of σac(ω) well described the Jonscher's power (σac(ω) = σdc + Aωs). In addition, the temperature dependence study of frequency exponent (S) is investigated to explain the conduction mechanism, which is attributed to the barrier hopping (CBH) model in the region I and II.Graphical abstract [ABSTRACT FROM AUTHOR]

Silver ion conducting glass system composed of xAgI-(100 − x)[0.444 Ag2SO4-0.555 (0.4TeO2-0.6B2O3)] has been prepared by melt quenching method for x = 0 to 80 in step of 10. XRD, DSC, FTIR, and SEM were carried out to understand some structural properties of prepared samples. XRD and DSC studies of the samples with x ≤ 60 show predominantly glassy nature. Electrical parameters and activation energies of all the samples were evaluated by complex impedance analysis and Arrhenius plots of DC conductivity, respectively. Carrier concentration, mobility, inter-ionic distance, and ionic conductivity of samples were measured and discussed. It is observed that the conductivity varies with increasing the temperature and composition. The highest conductivity (1.8 × 10−1 S cm−1) and ionic current (8.33 μA) is observed for = 50 sample at room temperature; hence, it can be used as best electrolyte material for solid-state battery application. [ABSTRACT FROM AUTHOR]

The sodium dihydrogen phosphate NaH2PO4 can be obtained by slow evaporation at room temperature and characterized by X-ray powder diffraction, scanning electron microscopy (SEM), and electrical impedance spectroscopy. The X-ray diffraction pattern revealed that the sample presents a single phase that crystallizes in the monoclinic structure with a P21/c space group, and the unit cell parameters are a = 6.8034 Å, b = 13.4014 Å, c = 7.2986 Å, and β = 92.827°. The dielectric impedance properties were studied over the range of frequency between 103 Hz and 1 MHz and in the temperature range of 300-440 K. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit model. The circuits consist of the parallel combination of resistance (R), fractal capacitance (CPE), and capacitance (C). Furthermore, the frequency-dependent AC conductivity obeys Jonscher’s universal power law. In fact, the near values of activation energy obtained from the modulus spectra and conductivity confirm that the transport happens through a proton-hopping mechanism, dominated by the motion of the proton H+ in the structure of the investigated materials. [ABSTRACT FROM AUTHOR]

The lithium dihydrogen phosphate LiH2PO4 has been investigated by X-ray powder diffraction, scanning electron microscopy (SEM), and electrical impedance spectroscopy. The Rietveld refinements based on the XRD patterns show that the compound is crystallized in the orthorhombic system with Pna21 space group, and the refined unit cell parameters are a = 6.2428 Å, b = 7.6445 Å, and c = 6.873 Å. The electrical properties were studied using complex impedance spectroscopy as a function of frequency (104-107 Hz) at various temperatures (300-400 K). The Nyquist plots are well fitted to an equivalent circuit consisting of a series of combination of grains and inhomogeneous electrode surface effect. The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. Moreover, the near value of the activation energies obtained from the equivalent circuit and analysis of M″ confirms that the transport is through ion hopping mechanism dominated by the motion of the proton in the structure of the investigated material. [ABSTRACT FROM AUTHOR]

The NaWO compound has been obtained by the conventional solid-state reaction and characterized by X -ay powder diffraction. The title material crystallizes in the cubic system with Fd-3m space group. The electrical properties of the compound have been studied using complex impedance spectroscopy in the frequency range 200 Hz-5 MHz and temperature range 586-679 K. Two semicircles are observed in impedance plot indicating the presence of two relaxation processes in the compound associated with the grain and grain boundary. The relaxation behavior of the grain and grain boundary of the NaWO are also obtained from the analyzed electrical modulus data. AC conductivity measured follows the power-law dependence σ∼ω typical for charge transport. Therefore, the experimental results are analyzed with various theoretical models. Temperature dependence of the power law exponent s strongly suggests that tunneling of large polarons is the dominant transport process. The mechanism of conduction is probably due from the displacements of the Na+ ion in the tunnel-type cavities along [111] direction. [ABSTRACT FROM AUTHOR]

Zinc potassium pyrophosphate KZnPO was synthesized using the conventional solid-state reaction. X-ray powder diffraction analysis proves the formation of a pure phase which crystallizes in the tetragonal system. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 614-718 K and 200 Hz-1 MHz, respectively, by means of impedance spectroscopy. The alternating current (AC) conductivity for grain contribution follows the universal Jonscher's power law. The frequency exponent s is temperature independent and equal to 0.8. The QMT model was proposed to be the most suitable model to characterize the electrical conduction mechanism in the titled sample. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The bulk relaxation time was found from the peaks position of the above spectra and the thermodynamic parameters were also found using the Eyring theory. [ABSTRACT FROM AUTHOR]

The lead-free polycrystalline Sr-substituted BaSrZrTiO (BSZT) ( x = 0.00-0.15) ceramics are synthesized by the high-temperature conventional solid-state reaction method. The Rietveld refinement of the X-ray diffraction pattern confirms the co-existence of tetragonal and cubic phase in the sample at x = 0.10, which is also confirmed from Raman spectroscopy. The surface micrographs show the formation of grains with well-defined grain boundaries and the significant enhancement in granular size with increasing Sr content. Moreover, the domain structure with 'lamellar' and watermark characters is clearly observed for all the concentrations. The complex impedance analysis shows a significant increment in the net impedance of BSZT samples for the composition, x = 0.10. Exceptionally high value of impedance is attributed to the co-existence of two competing phases in the microscopic level. An enhancement in the impedance value is a consequence of reduction in the electrical conductivity of the sample. The modulus analysis confirms the presence of non-Debye-type relaxation in the material. The frequency gap (Δ f) between the normalized master curve Z″ /Z″ and M″ /M″ decreases with increasing Sr concentration, which indicates a reduction in the polarization in BSZT samples. This result is well consistent with the results obtained from the complex impedance analysis. [ABSTRACT FROM AUTHOR]

The NaLiCdVO ( x = 0.5, 1) orthovanadates were prepared using a solid-state reaction method. The x-ray diffraction patterns (XRDP) of both materials reveal the formation of the NaCrO structure. Vibrational study confirms the existence of [VO] group. Electrical measurements of our compounds have been investigated using complex impedance spectroscopy (CIS) in the frequency and temperature range 209 Hz-1 MHz and 589-703 K, respectively. Nyquist plots reveal the presence of tow contributions, an equivalent circuit was proposed. DC conductivity shows electrical conduction in the material as a thermally activated process. The AC conductivity is explained using the non-overlapping small polaron tunneling (NSPT) conduction mechanism. A relationship between crystal structure and ionic conductivity was established and discussed. [ABSTRACT FROM AUTHOR]

New pyrophosphate of ceramic compounds LiNaAgPO ( x = 0.2 and 0.6) is synthesized by a solid-state method. All the compounds crystallize in the orthorhombic lattice with space group C222. The infrared spectra of these compounds show characteristic bands due to a PO group. The two semicircles observed in the complex impedance identify the presence of the grain interior and grain boundary contributions to the electrical response in these materials. The frequency independent conductivity of these compounds shows Arrhenius-type behavior. The activation energies have been calculated at the levels of impedance, electric modulus studies, and DC conductivity which suggest that the conductions are ionic in nature. The conductivity increases with an increase in Ag substitution. In order to determine the conduction mechanism, the AC conductivity and its frequency exponent have been analyzed in this work by a theoretical model based on quantum mechanical tunneling: the non-overlapping small polaron tunneling model (NSPT) is confirmed for x = 0.2 and x = 0.6. The conduction mechanism is studied with the help of Elliot's theory, and the Elliot's parameters are determined. [ABSTRACT FROM AUTHOR]

A lithium yttrium diphosphate LiYPO was prepared by a solid-state reaction method. Rietveld refinement of the X-ray diffraction pattern suggests the formation of the single phase desired compound with monoclinic structure at room temperature. The infrared and Raman spectrum of this compound was interpreted on the basis of PO vibrations. The AC conductivity was measured in the frequency range from 100 to 10 Hz and temperatures between 473 and 673 K using impedance spectroscopy technique. The obtained results were analyzed by fitting the experimental data to the equivalent circuit model. The Cole-Cole diagram determined complex impedance for different temperatures. The angular frequency dependence of the AC conductivity is found to obey Jonscher's relation. The temperature dependence of σ could be described in terms of Arrhenius relation with two activation energies, 0.87 eV in region I and 1.36 eV in region II. The study of temperature variation of the exponent(s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the correlated barrier hopping (CBH) model in region I ( T < 540 K) and non-overlapping small polaron tunneling (NSPT) model in region II ( T > 540 K). The near value of activation energies obtained from the equivalent circuit and DC conductivity confirms that the transport is through ion hopping mechanism dominated by the motion of the Li ion in the structure of the investigated material. [ABSTRACT FROM AUTHOR]

The copper monophosphate compound, α-AgCuPO, was prepared by the conventional solid-state reaction. The purity of the compound was checked by X-ray diffraction technique (XRD). Detailed dielectric and electrical properties of the compound were analyzed as a function of frequency (209 Hz-1 MHz) and temperature (343-514 K). The AC conductivity has been fitted and studied using Jonscher's equation, whose exponent n varied with the temperature, showing that the overlapping large polaron tunneling model (OLPT) is the appropriate model to describe the electrical conduction mechanism. [ABSTRACT FROM AUTHOR]

NaNiPO compound was obtained by the classic ceramic method at high temperature and was characterized by XRD. It was found to crystallize in the triclinic symmetry with the P-1 space group. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 586-723 K and 200 Hz-1 MHz, respectively, by means of impedance spectroscopy. The ac conductivity for grain contribution was interpreted using the universal Jonscher's power law. The exponent s decreased with increasing temperature revealing that the conduction inside the studied material is insured by the correlated barrier hopping (CBH) model. The conduction mechanism was explained with the help of Elliot's theory, and the Elliot's parameters were determined. Thermodynamic parameters such as the free energy for dipole relaxation ΔG, the enthalpy ΔH, and the change in entropy ΔS have been calculated. [ABSTRACT FROM AUTHOR]

The synthesis and conductivity study of 2-vinylpyridine-acrylonitrile copolymer and its hydroiodide/hydrofluoride salts are reported here. The copolymer and the polyelectrolytes are characterized by infrared, proton nuclear magnatic resonance, thermogravimatric analysis, differential scanning calorimetry, X-ray diffraction, and gel permeation chromatography techniques. The alternating current conductivities are measured within the temperature range 30-90 °C by varying the frequency from 42 Hz to 5 MHz and found to be significantly higher than that of the copolymer. There observed a 10- and 10-fold increase in ionic conductivities for the salts of HI and HF, respectively. The ionic transport numbers are measured with the help of standard Wagner polarization technique, and the values for HI and HF salts are 0.97 and 0.94, respectively, which are relatively higher than that of the copolymer (0.71). The apparent activation energies for conduction for the copolymer and its salts are also measured. [ABSTRACT FROM AUTHOR]

The high-temperature form of AgCuPO (i.e., β-AgCuPO) was obtained by conventional solid-state reaction. The sample was characterized by X-ray powder diffraction, Raman, and electrical impedance spectroscopy. Electrical properties were investigated using impedance measurements in the frequency range from 209 Hz to 1 MHz and the temperature range 603 to 719 K. Z′ and Z″ versus frequency plots were well fitted to an equivalent circuit model. It was found that the data of the ac measurements follow the correlated barrier hopping (CBH) model and the model's parameters were determined. [ABSTRACT FROM AUTHOR]

The polycrystalline samples of LiPO were prepared by solid-state reaction technique. The formation of the compounds was checked by X-ray diffraction technique (XRD). Detailed dielectric and electrical properties of the compounds were analyzed as a function of frequency (200 Hz-5 MHz) and temperature (611-671 K). The impedance data were well fitted to two equivalent electrical circuits. The results of the modulus study reveal the presence of two distinct relaxation processes suggesting the presence of grains and grain boundaries in the sample. Analysis of the dielectric constants ε″ and loss tangent tan ( δ) with frequency shows a distribution of relaxation times. The activation energy found from the Arrhenius plot confirms that the conduction process in the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent s was investigated to understand the conduction mechanism in LiPO. The overlapping large polaron tunneling (OLPT) model can explain the temperature dependence of the frequency exponent. [ABSTRACT FROM AUTHOR]

In the present study, different mole percent of SiO (~10-20 nm) was dispersed into 85.32[NaNO]-14.68[Sr(NO)] mixed system. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) characterizations were carried out on present dispersed system. Alternate current (AC) and direct current (DC) conductivities, dielectric constant, loss, and impedance measurements have been studied in the frequency range from 1 Hz to 10 MHz and in the temperature range from 297 to 553 K. The XRD, FTIR, SEM, and DSC studies of SiO dispersed systems reveal the formation of amorphous phase. The frequency dependent ac conductivity follows Jonscher's universal power law. Dimensionless frequency exponent ( n) and dispersion parameter ( A) are determined. The enhancement in dc conductivity is observed with the m/o of SiO in these electrolyte systems and attains maximum at 20.55 m/o, where from the enhancement starts falling with further increase in m/o, and this enhancement in conductivity is explained using the formation of amorphous phase of ionic salt. [ABSTRACT FROM AUTHOR]

The LiBaPO compound has been obtained by the conventional solid-state reaction and characterized by X-ray powder diffraction. The title material crystallizes in the monoclinic system with C2/c space group. Electrical properties of the compound have been studied using complex impedance spectroscopy in the frequency range 200 Hz-5 MHz and temperature range 589-724 K. Temperature dependence of the DC conductivity and modulus was found to obey the Arrhenius law. The obtained values of activation energy are different which confirms that transport in the titled compound is not due to a simple hopping mechanism. AC conductivity measured follows the power-law dependence σ ∼ ω typical for charge transport. Therefore, the experimental results are analyzed with various theoretical models. Temperature dependence of the power law exponent s strongly suggests that tunneling of large polarons is the dominant transport process. [ABSTRACT FROM AUTHOR]

Polymer gel electrolytes (PGE) belonging to salt-solvent-polymer hybrid systems are prepared using a mixture of lithium bis(oxalato)borate (LiBOB), γ-butyrolactone (γ-BL), and cellulose acetate (CA). The increase in ionic conductivity of PGE is due to the dissociation of ion aggregates, as confirmed by Fourier transform infrared analysis. The highest conductivity attained by the PGE is 7.05 mS cm at 2.4 wt.% CA. The plots of conductivity-temperature show a classical Arrhenius relationship. The electrical properties of the sample with the highest conductivity are analyzed using electrical permittivity and electric modulus formalism studies. Meanwhile, the frequency-dependent conductivity of the polymer gel electrolyte adheres to Jonscher's power law. Conduction mechanism study also shows that the 2.4 wt.% CA PGE is in agreement with the small polaron hopping model. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA) composites were prepared by controlled loading of Nafion (5 to 15 wt%) by solution casting using water and dimethylformamide (DMF) as a solvent. The surface morphology of composite analyzed by atomic force microscopy (AFM) reveals the presence of Nafion ionomers. The increase in interlayer spacing of modified PVDF/PVA polymer system as a function of Nafion was detected by X-ray diffraction (XRD). The major change in Fourier transform infrared (FTIR) spectroscopy confirms the chemical bond C=O stretching around 1,700 cm due to Nafion. Differential scanning calorimetry (DSC) demonstrates the thermal stability of polymer composites and the decrease in melting temperature ( T). The optimized AC conductivity (σ) of the prepared composite was evaluated by using an impedance analyzer as a function of temperature (40 to 150 °C) at constant 30-MHz frequency. The highest conductivity of 1.3 × 10 S m was observed at 80 °C for 10 wt% of Nafion and correlated with structure, morphology and thermal properties of modified PVDF/PVA/Nafion composites. The experimental results may be useful for sensors, fuel cells and battery application domains. [ABSTRACT FROM AUTHOR]

The LiNiPO compound was prepared by the solid-state reaction method at 923 K and characterized through XRD and Raman spectroscopy techniques. The impedance spectroscopy measurements were performed in the frequency and the temperature range (300 Hz-5 MHz) and (633-729 K), respectively. The ac conductivity for grain contribution is interpreted using the universal Jonscher's power low. The exponent n decreases with increasing temperature which reveals that the conduction inside the studied material is insured by the correlated barrier hopping (CBH) model. The parameters of CBH model were determined showing that the ac conduction is realised by single-polaron hopping mechanism. Thermodynamic parameters such as the free energy for dipole relaxation Δ F, the enthalpy Δ H, and the change in entropy ΔS have been calculated. [ABSTRACT FROM AUTHOR]

The NaNi(PO) compound was obtained by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction and vibrational and impedance spectroscopy. The AC electrical conductivity and the dielectric relaxation properties of this compound have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies and temperatures, 209 kHz-1 MHz and 564-729 K, respectively. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The peak positions ω of M″ spectra shift toward higher frequencies with increase in temperature. The AC conductivity data fulfill the power law. Application of the correlated barrier hopping model revealed that the ionic conduction takes place by single-polaron and bipolaron hopping processes. [ABSTRACT FROM AUTHOR]

The new organic-inorganic compound, tri-tetrapropylammonium dodeca chlorobismuthate(III), has been synthesized and characterized by single-crystal X-ray diffraction at room temperature. It is crystallized in the triclinic system ( $$ \mathrm{P}\overline{1} $$ space group). The atomic arrangement can be described by an alternation of two types of organic-inorganic layers stacked in [010] direction. The nature of the inorganic polyhedra distortion which can be attributed to the stereo activity of the Bi(III) lone electron pair has been studied. Regarding the differential scanning calorimetry, it disclosed one structural phase transition at T = 423 (±5) K of the order-disorder type. Furthermore, the dielectric properties of the compound were studied using complex impedance spectroscopy in the frequency range 209 Hz-5 MHz and temperature range 368-458 K. The frequency-dependent AC conductivity is well described by Jonscher's universal power law. The nature of DC conductivity variation suggests Arrhenius type of electrical conductivity. [ABSTRACT FROM AUTHOR]

The KFeP 2O 7 compound was prepared by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction. The AC electrical conductivity and the dielectric relaxation properties of this compound have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies and temperatures, 200 Hz–5 MHz and 553–699 K, respectively. Both impedance and modulus analysis exhibit the grain and grain boundary contribution to the electrical response of the sample. The temperature dependence of the bulk and grain boundary conductivity were found to obey the Arrhenius law with activation energies Eg = 0.94 (3) eV and Egb = 0.89 (1) eV. The grain-and-grain boundary conductivities at 573 K are 1.07 × 10 −4 and 1.16 × 10 −5 (Ω −1 cm −1). The scaling behavior of the imaginary part of the complex impedance suggests that the relaxation describes the same mechanism at various temperatures. The near value of the activation energies obtained from the equivalent circuit, conductivity data, and analysis of M″ confirms that the transport is through ion hopping mechanism. [ABSTRACT FROM AUTHOR]

The NaBaPO compound was obtained by conventional solid-state reaction. The sample was characterized by X-ray powder diffraction and electrical impedance spectroscopy. The impedance plots show semicircle arcs at different temperatures, and an electrical equivalent circuit has been proposed. The circuits consist of the parallel combination of bulk resistance R and constant phase elements CPE. The dielectric relaxation is described by a non-Debye model. The frequency dependence of the conductivity is interpreted in term of the well-known universal dynamic response $$ {\sigma_{\mathrm{ac}}}={\sigma_{\mathrm{dc}}}\left[ {1+{{{\left( {{\omega \left/ {{{\omega_h}}} \right.}} \right)}}^n}} \right] $$. The near value of activation energies obtained from the analyses of M″, conductivity data and equivalent circuit confirms that the transport is through ion hopping mechanism dominated by the motion of the Na ions in the structure. The better properties obtained for NaBaPO can be attributed to the Ba derivatives' larger size of the bottlenecks along the channels. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the effect of dedoped (insulating) polyaniline (PAni) nanofibers on the electrical and electrochemical properties of poly(methyl methacrylate) (PMMA)-based gel electrolytes. PAni nanofibers have been synthesized using interfacial polymerization technique. By analysis of X-ray diffraction (XRD) and impedance spectroscopy results, it has been demonstrated that the incorporation of dedoped PAni nanofibers up to a moderate concentration (4 wt%) to PMMA-(PC + DEC)-LiClO gel polymer electrolyte system significantly enhances the ionic conductivity of the electrolyte system, which can be attributed to the inhibition of polymer chain reorganization upon dispersion of high aspect ratio nanofibers in PMMA matrix resulting in reduction in polymer crystallinity, which gives rise to an increase in ionic conductivity. At higher concentration, dedoped nanofibers appear to get phase separated and form insulating clusters, which impede ionic transport. The phase separation phenomena at higher fraction of nanofibers are confirmed by XRD. Studies on electrochemical behavior reveal that electrochemical potential window increases with the increase of nanofibers loading. [ABSTRACT FROM AUTHOR]

Pyrochlore-structured materials are very important materials due to their structural and conducting properties. These properties can be further modified by changing processing conditions. In the present study, pyrochlore (YTiO) is synthesized using high-energy ball milling. During various stages of ball milling, the ball-milled powder is taken for investigating the structural and thermal properties. The replacement of TiO by TiO in nominal composition leads to lower ball milling duration to form YTiO. Differential thermal analysis showed the single exothermic peak below 800 °C, which indicates formation of disordered pyrochlore phase. The as prepared powders (40-h ball milled) were compacted and heat treated at 1,450 °C for 12 h. The conductivity of sintered sample is found to be one order higher than earlier reported pure YTiO pyrochlore. [ABSTRACT FROM AUTHOR]

The bis (3-dimethylammonium-1-propyne) pentachlorobismuthate (III) exhibits a structural phase transition at T = (337 ± 2 K), which has been characterized by differential scanning calorimetric, X-ray powder analysis, AC conductivity and dielectric measurements. The dielectric dispersion yielded the real and imaginary parts of impedance of (CHN)BiCl in the form of a semicircle in a complex plane. Besides, a Cole-Cole plot was observed at frequencies ranging from 209 Hz to 5 MHz, whose result was found to fit the theoretical resistor-capacitor parallel circuit model. The temperature dependence of the electrical conductivity in the different phases follows the Arrhenius law. The frequency-dependent conductivity data were fitted in the modified power law: $$ \sigma = {\sigma_{dc}} + {B_1}(T){\omega^{{s_1}}} + {B_2}(T){\omega^{{s_2}}} $$. The imaginary part of the permittivity constant is analyzed with the Cole-Cole formalism. With regard to the modulus plot, it can be characterized by full width at half height or in terms of a non-exponential decay function $$ \phi (t) = \exp {\left( {\frac{{ - t}}{{{\tau_\sigma }}}} \right)^\beta } $$. Besides, the activation energy responsible for relaxation has been evaluated and found to be close the DC conductivity. [ABSTRACT FROM AUTHOR]

In the present work, we report a novel nanocomposite gel electrolytes based on intercalation of hyperbranched polyurethane (HBPU) into organically modified montmorillonite for application in Li-ion batteries. The nanocomposites have been prepared by solution intercalation technique with varying clay loading. The formation of partially exfoliated nanocomposites has been confirmed by X -ray diffraction. Nanocomposites were soaked with 1 M LiCO in 1:1 ( v/ v) solution of propylene carbonate and diethyl carbonate to get the required gel electrolytes. AC impedance analysis shows that ionic conductivity increases with the increase of clay loading and attains the highest value of 8.3 × 10 S/cm for 5 wt.% clay concentration. Surface morphology of the nanocomposite electrolytes has been examined by SEM analysis. Improvement of electrochemical properties, viz., electrochemical potential window and interfacial stability, is also observed in the clay-loaded HBPU samples. [ABSTRACT FROM AUTHOR]

The effect of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) blending on the electromechanical and electrical properties of cellulose was premeditated by taking bending actuator test and electrical impedance analysis. Dispersion of BMITFSI in cellulose matrix was carried out by solution blending technique. Upon blending BMITFSI, bending displacement of the actuator was enhanced by eight times as compared to that of the pristine cellulose. Similar improvement in the AC conductivity of cellulose was observed. The effect of BMITFSI content and humidity on electromechanical and electrical properties of BMITFSI-loaded cellulose was discussed. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid sample [N(CH)]CuCl was prepared via the reaction between copper chloride and tetrabutylammonium chloride. The compound was characterized by X-ray powder diffraction, IR, Raman, differential scanning calorimetry (DSC), DTA-TGA analysis and electrical impedance spectroscopy. DSC studies indicate a presence of one-phase transition at 343 K. The complex impedance of compound [N(CH)]CuCl have been investigated in temperature and frequency ranges 300-380 K and 200 Hz-5 MHz, respectively. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit model. The circuits consist of the parallel combination of bulk resistance R and constant phase elements CPE. The frequency dependence of the conductivity is interpreted in term of Jonscher's law: $$ \sigma (\omega ){ } = {\sigma_{\rm{dc}}} + { }A{\omega^n} $$. The conductivity follows the Arrhenius relation. The variation of the value of these elements with temperatures confirmed the availability of the phase transition at 343 K detected by DSC and electrical measurements. [ABSTRACT FROM AUTHOR]

NaAgPbPO was prepared with a solid-state reaction. The electrical properties were investigated by using impedance measurements in the frequency range from 200 Hz to 5 MHz with the TEGAM 3550 ALF automatic bridge monitored by a microcomputer between 581 K and 703 K. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit model. The conductivity data obey the universal power law. The conductivity in the material is due to the hopping of monovalent ions parallel to (001) plane. [ABSTRACT FROM AUTHOR]

Although the conductivity measurement on La2Mo2O9 is well documented, the ion dynamic study is scarcely reported. Here, we report on the AC impedance measurement of La2Mo2O9 in the light of ion dynamics. We have examined the low-temperature regime, 250 °C to 500 °C, i.e., basically the characteristics of low-temperature α form, on the basis of frequency dispersion of conductivity as well as in terms of modulus formalism. The relationship of the values of the exponential parameter, s of universal dielectric response (UDR), and the stretching exponent, β of Kohlrausch–Williams–Watts (KWW), were evaluated from curve fitting. The temperature dependence of such parameters is checked and is interpreted for the plausible mechanism of ionic motion in the material at low temperature. [ABSTRACT FROM AUTHOR]

An attempt has been made to prepare a new proton conducting polymer electrolyte based on polyvinyl alcohol (PVA) doped with NH4NO3 by solution casting technique. The complex formation between polymer and dissociated salt has been confirmed by X-ray diffraction analysis. The ionic conductivity of the prepared polymer electrolyte has been found by ac impedance spectroscopic analysis. The highest ionic conductivity has been found to be 7.5 × 10−3 Scm−1 at ambient temperature for 20 mol% NH4NO3-doped PVA with low activation energy (~0.19 eV). The temperature-dependent conductivity of the polymer electrolyte follows an Arrhenius relationship, which shows hopping of ions in the polymer matrix. [ABSTRACT FROM AUTHOR]

Homogeneous (LiCl) x (P2O5)1 − x glasses were synthesised using a melt-quenching method for x = 0.1–0.6 in the interval of 0.05. The amorphous structure of the samples was evident by the X-ray diffraction spectrum. The short range structures of the binary phosphate samples were examined by Fourier transform infrared spectroscopy, whilst the density of the samples was measured as supportive data for the investigations. The results of refractive indices as measured using an ellipsometer reveal the homogeneity of samples and was found to depend on the glass composition. The electrical properties of the glasses were investigated by ac impedance spectroscopy from 10 mHz to 1 MHz for temperatures ranging from room temperature to 573 K. An estimation of the bulk resistivity was obtained by taking the intercepts on the real axis at low frequencies of the complex impedance plot. The dc conductivities derived from the reciprocal of resistivity values were found to obey the Arrhenius relationship, and its activation energy shows a decreasing trend with the increase in LiCl content in the glass. Lastly, an equivalent circuits consisting of real and complex capacitors is proposed to describe the dielectric response of the glass. [ABSTRACT FROM AUTHOR]

Electrical conductivity and dielectric relaxation studies of silver ion-conducting glasses have been prepared using xAg2SO4-15Ag2O-(90-x)(90P2O5-10MoO3) glass system over a temperature range of 298–353 K and frequencies of 10 Hz to 10 MHz. DC conductivities exhibit Arrhenius behavior over the entire temperature range with a single activation barrier. The ac conductivity behavior of these glasses has been analyzed using single power law; conductivity increases linearly in logarithmic scale with Ag2SO4 concentration. The power law exponent ( s) decreases, while stretched exponent ( β) is insensitive to increase of temperature. Scaling behavior has also been carried out using the reduced plots of conductivity and frequency, which suggest that ion transport mechanism remains unaffected at all temperatures and compositions. [ABSTRACT FROM AUTHOR]

Films of hexanoyl chitosan-based polymer electrolyte were prepared by the technique of solution casting. The effect of plasticizer on the transport properties of hexanoyl chitosan:lithium trifluoromethanesulfonate (LiCF3SO3) electrolytes have been investigated. The plasticizer used was ethylene carbonate (EC). The highest room temperature conductivity achieved in the EC-plasticized hexanoyl chitosan-based electrolytes is 2.75×10−5 S cm−1. The Rice and Roth model was used to explain the variations in the dc conductivity observed. The exponent, s, in Jonscher’s universal power law equation σ( ω)= σ dc+ Aω s , was analyzed as a function of temperature for the sample containing 30 wt% of EC. The analysis suggests that the conduction mechanism follows that proposed by the overlapping large polaron tunneling model. [ABSTRACT FROM AUTHOR]