Structural,thermal and electrical properties of polyvinyl alcohol/poly(vinyl pyrrolidone)–sodium nitrate solid polymer blend electrolyte

Sodium ion conducting solid polymer blend electrolyte thin films have been prepared by using polyvinyl alcohol (PVA)/poly(vinyl pyrrolidone) (PVP) with NaNO₃ by solution cast technique. The prepared films were characterized by various methods. The complexation of the salt with the polymer blend was identified by X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR), Differential scanning calorimetry was used to analyze the thermal behavior of the samples, and the glass transition temperature is low for the highest conducting polymer material. The scanning electron microscopy gives the surface morphology of the polymer electrolytes. The frequency and temperature dependent of electrical conductivities of the films were studied using impedance analyzer in the frequency range of 1 Hz to 1 MHz. The highest electrical conductivity of 50PVA/50PVP/2 wt% NaNO₃ concentration has been found to be 1.25 × 10^?5 S cm^?1 at room temperature. The electrical permittivity of the polymer films have been studied for various temperatures. The transference number measurements showed that the charge transport is mainly due to ions than electrons. Using this highest conducting polymer electrolyte, an electrochemical cell is fabricated and the parameters of the cells are tabulated.     

Effect of ethylene carbonate concentration on structural and electrical properties of PEO–PMMA polymer blends

Polyethylene oxide–polymethyl methacrylate (PEO–PMMA) polymer blend electrolyte system complexed with silver salt having different ethylene carbonate (EC) concentrations was prepared using solution cast technique. Complex formation and change in structural and microstructural properties have been studied by X-ray diffraction, Fourier transform infrared, and scanning electron microscopy analysis. The thermal properties of polymer films have been examined by the differential scanning calorimetry technique. Addition of plasticizer is observed to lower melting temperature. Electrical response of polymer films has been measured as a function of EC concentration and temperature using complex impedance spectroscopy. Complex impedance data are used to analyze the conductivity, permittivity, and modulus formalism to understand the conduction mechanism. The temperature dependence of electrical conductivity of polymer electrolytes shows a sudden rise at the melting temperature of PEO.     

Characterization of high ionic conducting PVAc–PMMA blend-based polymer electrolyte for electrochemical applications

A solid polymer blend electrolyte is prepared using poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) polymers with different molecular weight percentage (wt%) of ammonium thiocyanate (NH₄SCN) by solution casting technique with tetrahydrofuran (THF) as a solvent. The structural, morphological, vibrational, thermal and electrical properties of the prepared polymer blend electrolytes have been studied. The incorporation of NH₄SCN into the polymeric matrix causes decrease in the degree of crystallinity of the samples. The complex formation between the polymer and salt has been confirmed by FTIR technique. The increase in T _g with increase in salt concentration has been investigated. The maximum conductivity of 3.684?×?10^?3 S cm^?1 has been observed for the composition of 70PVAc/30PMMA/30 wt% of NH₄SCN at 303 K. This value of ionic conductivity is five orders of magnitude greater than that of 70PVAc/30PMMA polymer membrane. Dielectric and transport studies have been done. The highest conducting polymer electrolyte is used to fabricate proton battery with the configuration Zn/ZnSO₄·7H₂O (anode) ||polymer electrolyte||PbO₂/V₂O₅ (cathode). The open circuit voltage of the fabricated battery is 1.83 V, and its performance has been studied.     

Effect of nanofillers on thermal and transport properties of potassium iodide–polyethylene oxide solid polymer electrolyte

In order to enhance the ionic conductivity of polyethylene oxide (PEO)–KI(80:20) based alkaline polymer electrolytes, nanosized inorganic filler ZnS has been incorporated into PEO–KI matrix and the corresponding nanocomposite polymer electrolytes are synthesized by the usual solution casting procedure. Atomic force microscope image of composite polymer electrolyte exhibits that the introduction of ZnS nanoparticles changes the surface morphology and aggregates them to form an arborization pattern. The prepared nanocomposite polymer electrolyte reveals an ionic conductivity of about 10^?4 S cm^?1 for 5 wt% ZnS at room temperature.     

Synthesis, structural, optical and electrical properties of metal nanoparticle–rare earth ion dispersed in polymer film

Cu-nanoparticles have been prepared by ablating a copper target submerged in benzene with laser pulses of Nd:YAG (wavelength: 355, 532 nm and 1,064 nm). Colloidal nanoparticles have been characterized by UV–Vis spectroscopy and transmission electron microscopy. The obtained radius for the nanoparticles prepared using 1,064 nm irradiation lies in the range 15–30 nm, with absorption peak at 572 nm. Luminescence properties of Tb³⁺ ions in the presence and absence of Cu-nanoparticles have been investigated using 355 nm excitation. An enhancement in luminescence of Tb³⁺ by local field effect causing increase in lifetime of ⁵D₄ level of Tb³⁺ ion has been observed. Frequency and temperature-dependent conductivity of Tb³⁺ doped PVA thin films with and without Cu-nanoparticles have been measured in the frequency range 20 Hz–1 MHz and in the temperature range 318–338 K (well below its melting temperature). Real part of the conductivity spectra has been explained in terms of power law. The electrical properties of the thin films show a decrease in dc conductivity on incorporation of the Cu-nanoparticles.     

Effect of LiBOB as additive on electrochemical properties of lithium–sulfur batteries

The effect of varying amounts (in the range 1–10 wt.%) of LiBOB (lithium bis(oxalato) borate) as additive in mixed liquid electrolyte on the electrochemical performance of lithium–sulfur batteries is investigated at room temperature. The electrochemical impedance spectroscopy (EIS) of lithium anode with LiBOB has two semicircles, corresponding to charge transfer impedance and ion migration impedance, respectively. The lithium anode with LiBOB shows a higher ion migration impedance, which could reduce the ionic diffusion rate in the anode. Scanning electron microscopy (SEM) observations shows that lithium anode with LiBOB has a smoother and denser surface morphology than the anode without LiBOB. The lithium–sulfur batteries with LiBOB shows the improvement of both the discharge capacity and cycle performance, a maximum discharge capacity of 1,191 mA h g⁻¹ is obtained with 4 wt.% LiBOB. The lithium–sulfur batteries with 4 wt.% LiBOB can maintain a reversible capacity of 756 mA h g⁻¹ after 50 cycles.     

Role of electrolyte pH on structural and magnetic properties of Co–Fe films

Co–Fe films were electrodeposited on polycrystalline Titanium substrates from the electrolytes with different pH levels. X-ray diffraction (XRD) was used to study the crystal structure of the films. The XRD patterns showed that the films grown at the pH levels of 3.70 and 3.30 have a mixed phase consisting of face-centred cubic (fcc) and body-centred cubic, while those grown at pH=2.90 have only fcc structure. It was observed that the film composition, by energy dispersive x-ray spectroscopy, contain around 88 at% Co and 12 at% Fe for all films investigated in this study. Morphological observations indicated that all films have grainy structure with the slight change of grain size depending on the electrolyte pH. Magnetoresistance measurements, made at room temperature, showed that all films exhibited anisotropic magnetoresistance, which is affected by the electrolyte pH. From the magnetic measurements made by vibrating sample magnetometer, the saturation magnetization increases as the electrolyte pH decreases. Furthermore, all films have in-plane easy-axis direction of magnetization.     

Correlation study of structural,electrical and mechanical properties of quenched tin–zinc–cadmium solder alloys

It is important, for electronic application, to decrease the melting point of SnZn₉ solder alloy because it is too high as compared with the most popular eutectic Pb–Sn solder alloy. Adding Cd causes structural changes such as phase transformations, dissolution of atoms and formation of Cd crystals in the quenched SnZn₉ alloy, and its physical properties are affected by this change. For example, the melting point is decreased towards the melting point of the Pb–Sn eutectic alloy, or even much less. The structure, electrical and mechanical properties of quenched Sn_{91? x} Zn₉Cd _x (x?=?0 or x?≥?5) alloys have been investigated. Adding Cd to a quenched SnZn₉ alloy increases its electrical resistivity and decreases its elastic modulus and internal friction. The Sn₇₁Zn₉Cd₂₀ alloy has the lowest melting point (162 °C) and electrical and internal frictions as compared with commercial Pb–Sn solder alloys.     

Structural and electrical properties of Ga–Te systems under high pressure

First-principles evolutionary calculation was performed to search for all probable stable Ga–Te compounds at extreme pressure. In addition to the well-known structures of P6_3/mmc and Fm-3 m Ga Te and I4/m Ga_2 Te_5, several new structures were uncovered at high pressure, namely, orthorhombic I4/mmm GaTe_2 and monoclinic C2/m Ga Te_3, and all the Ga–Te structures stabilize up to a maximum pressure of 80 GPa. The calculation of the electronic energy band indicated that the high-pressure phases of the Ga–Te system are metallic, whereas the low-pressure phases are semiconductors. The electronic localization functions(ELFs) of the Ga–Te system were also calculated to explore the bond characteristics. The results showed that a covalent bond is formed at low pressure, however, this bond disappears at high pressure, and an ionic bond is formed at extreme pressure.     

Correlation between photographic and electrical properties of the polymer–semiconductor–salt of metal photosensitive composition

In the current paper experimental data about changes in the electrical properties (relative permittivity) of the PVA–ZnO–BiCl₃ photosensitive composition under UV radiation are presented. Also the correlation between dielectric constant and density of optical blackening are investigated.     

Electrical properties of a solid polymeric electrolyte of PVC–ZnO–LiClO4

The ZnO filler has been introduced into a solid polymeric electrolyte of polyvinyl chloride (PVC)–ZnO–LiClO₄, replacing costly organic filler for conductivity improvement. Ionic conductivity of PVC–ZnO–LiClO₄ as a function of ZnO concentration and temperature has been studied. The electrolyte samples were prepared by solution casting technique. The ionic conductivity was measured using impedance spectroscopy technique. It was observed that the conductivity of the electrolyte varies with ZnO concentration and temperature. The temperature dependence on the conductivity of electrolyte was modelled by Arrhenius and Vogel–Tammann–Fulcher equations, respectively. The temperature dependence on the conductivity does not fit in both models. The highest room temperature conductivity of the electrolyte of 3.7 × 10⁻⁷ Scm⁻¹ was obtained at 20% by weight of ZnO and that without ZnO filler was found to be 8.8 × 10⁻¹⁰ Scm⁻¹. The conductivity has been improved by 420 times when the ZnO filler was introduced into the PVC–LiClO₄ electrolyte system. It was also found that the glass transition temperature of the electrolyte PVC–ZnO–LiClO₄ is about the same as PVC–LiClO₄. The increase in conductivity of the electrolyte with the ZnO filler was explained in terms of its surface morphology.     

50 MeV Li3+ ion irradiation effect on structural, electrical, and dielectric properties of PVA-based nanocomposite polymer electrolytes

Nanocomposite polymer electrolyte thin films of polyvinyl alcohol (PVA)-orthophosphoric acid (H₃PO₄)-Al₂O₃ have been prepared by solution cast technique. Films are irradiated with 50 MeV Li³⁺ ions having four different fluences viz. 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions/cm². The effect of irradiation on polymeric samples has been studied and characterized. X-ray diffraction spectra reveal that percent degree of crystallinity of samples decrease with ion fluences. Glass transition and melting temperatures have been also decreased as observed in differential scanning calorimetry. A possible complexation/interaction has been shown by Fourier transform infrared spectroscopy. Temperature-dependent ionic conductivity shows an Arrhenius behavior before and after glass transition temperature. It is observed that ionic conductivity increases with ion fluences and after a critical fluence, it starts to decrease. Maximum ionic conductivity of ～2.3?×?10^?5 S/cm owing to minimum activation energy of ～0.012 eV has been observed for irradiated electrolyte sample at fluence of 5?×?10¹¹ ions/cm². The dielectric constant and dielectric loss also increase with ion fluences while they decrease with frequency. Transference number of ions shows that the samples are of purely ionic in nature before and after ion irradiation.     

Effect of lithium thiocyanate addition on the structural and electrical properties of biodegradable poly(ε-caprolactone) polymer films

Polymer electrolyte films of biodegradable poly(ε-caprolactone) (PCL) doped with LiSCN salt in different weight ratios were prepared using solution cast technique. The effect of crystallinity and interaction between lithium ions and carbonyl groups of PCL on the ionic conduction of PCL:LiSCN polymer electrolytes was characterized by X-ray diffraction (XRD), optical microscopy, Fourier transform infrared spectroscopy (FTIR) and AC impedance analysis. The XRD results revealed that the crystallinity of the PCL polymer matrix decreased with an increase in LiSCN salt concentration. The complexation of the salt with the polymer and the interaction of lithium ions with carbonyl groups of PCL were confirmed by FTIR. The ionic conductivity was found to increase with increasing salt concentration until 15 wt% and then to decrease with further increasing salt concentration. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the activation energy for conduction decreased with increasing LiSCN concentration up to 15 wt%. UV–vis absorption spectra were used to evaluate the optical energy band gaps of the materials. The optical energy band gap shifted to lower energies with increasing LiSCN salt concentration.     

Preparation,properties, and Li-ion battery application of EC + PC-modified PVdF-HFP gel polymer electrolyte films

Based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and lithium tetrafluoroborate (LiBF₄) salt along with blending plasticizers, ethylene carbonate (EC) and propylene carbonate (PC), high Li-ion-conducting gel polymer electrolyte films are developed. Their properties are characterized by various techniques. The ambient temperature ionic conductivity of the 85PVdF-HFP:15LiBF₄ + 150(EC + PC) electrolyte film has a high value of 8.1 × 10^?4 S cm^?1. Its crystallinity, melting point, and electrochemical stability window are 9.5%, 115 °C, and 4.6 V, respectively. The mechanical testing shows that the Young’s modulus, yield strength, and breaking strain of this electrolyte film are 36.8 MPa, 3.4 MPa, and 320%, respectively. Lithium-ion batteries based on the gel polymer electrolyte film exhibit remarkable charge–discharge and cycling performances. The initial discharge capacity of this battery is as high as 165.1 mAh g^?1 at 0.1 C and just shows a small capacity fading of 4.8% after 120 cycles, indicating that the 85PVdF-HFP:15LiBF₄ + 150(EC + PC) system is an excellent electrolyte candidate for lithium-ion battery applications. The charge–discharge performance of the Li-ion cell fabricated with this gel polymer electrolyte film is apparently better than that of the previously reported Li-ion cells fabricated with other PVdF-HFP-based gel polymer electrolyte films.     

Effect of dopants on the structural,optical and electrical properties of sol–gel derived ZnO semiconductor thin films

Undoped, Ga-, In-, Zr-, and Sn-doped ZnO transparent semiconductor thin films were deposited on alkali-free glasses by sol–gel method. 2-methoxyethanol (2-ME) and diethanolamine (DEA) were chosen as a solvent and a stabilizer, respectively. The doping concentration was maintained at 2 at.% in the impurity doping precursor solutions. The effects of different dopants on the structural, optical, and electrical properties of ZnO thin films were investigated. XRD results show that all annealed ZnO-based thin films had a hexagonal (wurtzite) structure. ZnO thin films doped with impurity elements obviously improved the surface flatness and enhanced the optical transmittance. All impurity doped ZnO thin films showed high transparency in the visible range (>91%). The Ga- and In- doped ZnO thin films exhibited higher Hall mobility and lower resistivity than did the undoped ZnO thin film.     

Study on phase stabilization and electrical performance of BICO0.20−xNIxVOX solid electrolyte

BICO_0.20?xNI_xVOX solid electrolyte in the composition range 0 ≤ x ≤ 0.20 was synthesized by standard solid-state reactions. The influence of Ni substitution for Co on the relationship between the phase stabilization and electrical performance was investigated by means of X-ray powder diffraction (XRPD), differential thermal analysis (DTA) and AC impedance spectroscopy. The highly conductive γ′-phase was effectively stabilized at room temperature for compositions with x ≥ 0.13 whose thermal stability increases with Ni content. On the other hand, complex plane plots of impedance suggested a major contribution of polycrystalline grain interiors to the overall electrical conductivity and the fastest oxygen-vacancy diffusion in the perovskite vanadate layers at x = 0.13. The dielectric permittivity measurements revealed the fact that suppression of the ferroelectric transition is compositionally dependent. However, a maximum ionic conductivity at lower temperatures (～2.56 × 10^?4 S cm^?1 at 300 °C) was observed for the composition with x = 0.13.     

Grain boundary effect on structural,optical, and electrical properties of sol–gel synthesized Fe-doped SnO_2 nanoparticles

Tin oxide(SnO_2) and iron-doped tin oxide(Sn_(1-x)Fe_xO_2,x=0.05 wt%,0.10 wt%) nanoparticles are synthesized by the simple sol-gel method.The structural characterization using x-ray diffraction(XRD) confirms tetragonal rutile phases of the nanoparticles.The variations in lattice parameters and relative intensity with Fe-doping concentration validate the incorporation of iron into the lattice.The compressive strain present in the lattice estimated by using peak profile analysis through using Williamson-Hall plot also exhibits the influence of grain boundary formation in the lattice.The radiative recombination and quenching observed in optical characterization by using photoluminescence spectrum(PL) and the shift in the band gap estimated from UV-visible diffused reflectance spectrum corroborate the grain boundary influence.Raman spectrum and the morphological analysis by using a field emission scanning electron microscope(FESEM) also indicate the formation of grain boundaries.The compositional analysis by using energy dispersive x-ray spectrum(EDAX) confirms Fe in the SnO_2 lattice.The conductivity studies exhibit that the impendence increases with doping concentration increasing and the loss factor decreases at high frequencies with doping concentration increasing,which makes the Sn_(1-x)Fe_xO_2 a potential candidate for device applications.     

Ferroelectric,pyroelectric and electrical properties of new tungsten–bronze tantalate

The polycrystalline sample of Li₂Pb₂Y₂W₂Ti₄Ta₄O₃₀ was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray structural analysis confirms the formation of a single-phase compound. The surface morphology of the sintered pellet sample recorded by SEM (scanning electron microscope) exhibits a uniform grain distribution with few voids. Detailed studies of dielectric constant, tangent loss and remanent and spontaneous polarization with temperature and frequency exhibit the existence of ferroelectricity in the material. The temperature and frequency dependence of impedance parameters (impedance, modulus, etc) of the material exhibits a strong correlation between these electrical parameters with its micro-structure (i.e., bulk, grain boundary, etc). The nature of variation of pyroelectric-coefficient and current with temperature suggests that material has good pyroelectric properties useful for fabrication of pyroelectric detector.