PAN–PEO solid polymer electrolytes with high ionic conductivity

The transparent and flexible solid polymer electrolytes (SPEs) are fabricated from polyacrylonitrile–polyethylene oxide (PAN–PEO) copolymer. The formation of the copolymer is confirmed by Fourier-transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC) measurements. The effects of acrylonitrile (AN) wt% content and M_n(PEO) on ionic conductivity are investigated by alternating current (ac) impedance spectroscopy. By controlling and adjusting the AN wt% content and doping PEO with high molecular weight, the ionic conductivity of SPEs is optimized. The ionic conductivity of PAN–PEO solid polymer electrolytes is found to be high 6.79 × 10⁻⁴ S cm⁻¹ at 25 °C with an [EO]/[Li] ratio of about 10, and are electrochemically stable up to about 4.8 V versus Li/Li⁺. The conductivity and interfacial resistance remain almost constant even at 80 °C.     

Polymer electrolyte based dye-sensitized solar cell with rice starch and 1-methyl-3-propylimidazolium iodide ionic liquid

Biodegradable rice starch was used to prepare solid polymer electrolytes (SPEs) using sodium iodide salt. The polymer electrolytes are prepared using solution cast technique. 1-methyl-3-propylimidazolium iodide (MPII) ionic liquid was incorporated in the polymer electrolyte. The ionic conductivity of SPEs are measured and temperature-dependent behavior of SPEs studied. All the solid polymer electrolytes follow Arrhenius type of thermal activated model. The ionic conductivity increased after addition of MPII ionic liquid. The highest ionic conductivity of 1.20 × 10^− 3 S cm^− 1 is achieved upon addition of 20 wt.% of MPII ionic liquid. Structural properties of polymer electrolytes are studied with FTIR and XRD which confirmed complexation between polymer and ionic liquid. The polymer electrolytes are analyzed for thermal study using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dye-sensitized solar cells (DSSC) are fabricated using polymer electrolytes and studied under Sun simulator. The highest energy conversion efficiency of 2.09% is attained after addition of 20 wt.% of MPII ionic liquid.     

Preparation and conductivity of hybrid materials containing undecatungstocobaltoindic heteropoly acid and polymer matrix

Hybrid organic–inorganic proton conductors (PEG/InCoW₁₁ and PVP/InCoW₁₁) were prepared by polyethylene glycol (PEG) or polyvinylpyrrolidone (PVP) and undecatungstocobaltoindic heteropoly acid (InCoW₁₁). The hybrid materials were characterized by the infrared (IR) spectra and the impedance spectra. The results reveal that the conductivity of hybrid materials is 7.08 × 10^− 3 and 1.95 × 10^− 3 S cm^− 1 at room temperature, respectively. According to the experimental results, we proposed a possible mechanism of the proton conduction of the hybrid materials.     

Electrical and thermal conductivity in Mg–5Sn Alloy at different aging status

The electrical conductivity, thermal conductivity and its relationship with the microstructure in Mg–5Sn alloy aged at 513 K for different aging times were investigated systematically in this paper. The results show that the electrical conductivity and thermal conductivity obviously increase with the increasing aging time, and its values increase from 10.25 × 10⁶ S·m^− 1 to 13.7 × 10⁶ S·m^− 1, 87.5 W·m^− 1·K^− 1 to 122 W·m^− 1·K^− 1 after aging treatment for 120 h, respectively. Meanwhile, it is found that there exist quite different relationships between unit cell volume and thermal conductivity in early and later aging stages.     

Synthesis and properties of Ce1−xGdxO2−x/2 solid solution prepared by flame spray pyrolysis

Flame spray pyrolysis, which produces ultrafine particles, was applied to the synthesis of Ce_1−xGd_xO_2−x/2 solid solutions by substituting Gd from a mole fraction of 0–0.40. The solubility limit of Gd in the Ce_1−xGd_xO_2−x/2 solid solution produced by flame spray pyrolysis was between 0.25 and 0.30, which is consistent with the reported value. The as-prepared Ce_1−xGd_xO_2−x/2 particles had a square morphology and a nanometer range in the equivalent diameter. The small particle size made it possible to reduce the sintering temperature of the Ce_1−xGd_xO_2−x/2 solid solution from 1650 °C to 1400 °C for the ceria-based solid electrolytes produced by the solid state preparation. The maximum ionic conductivity was achieved when the mole fraction of Gd was 0.25. The mole fraction for the highest ionic conductivity was the same as the particles produced by hydrothermal synthesis. However, the ionic conductivity of the Ce_1−xGd_xO_2−x/2 prepared by the flame spray pyrolysis (1.01 × 10⁻² S/cm at 600 °C) was higher than that prepared by the hydrothermal synthesis (7.53 × 10⁻³ S/cm at 600 °C).     

Synthesis and dc conductivity of Nd2/3TiO2.988

The A-site deficient perovskite Nd_2/3TiO_3 − δ was synthesized under an H₂–CO₂ gas mixture. The sample was found to have slight oxygen deficiency of δ∼0.012. The crystal structure was assigned to a double perovskite structure with orthorhombic space group Pmmm, as in the case of La_2/3TiO_3 − δ. Electrical conductivity measurement has also been performed. The temperature dependence of conductivity shows that electronic transport in Nd_2/3TiO_2.988 is well described by Emin–Holstein adiabatic small polaron model. The polaron density extracted from the conductivity measurement is ∼1.96 × 10²⁰ cm^− 3. This result agrees well with nominal polaron density for Nd_2/3TiO_2.988, ∼2.1 × 10²⁰cm^− 3. We have also derived important quantities for transport in Nd_2/3TiO_2.988.     

Synthesis of electrically active biopolymer–SiO2 nanocomposite aerogel

Silica nanoparticles encapsulated acacia gum–silica (AgSiO₂) composites were synthesized through sol–gel method using tetraethyl orthosilicate (TEOS) as silica precursor in basic condition. The nanocomposite gels were dried at different temperatures to form aerogels. The incorporation of nanostructured silica will influence the electronic behavior of composite. The composition of silica with acacia gum was tailored to optimize the material having good electronic properties. The resulting material was characterized by FTIR, XRD and AFM. The control curing of the composite resulted to mesoporous material with nanosize silica. At optimum composition, electrical conductivity and ion transference number of hybrid material are found to be 18.3 × 10^− 2 Scm^− 1 and 4.26 × 10² cm² V^− 1 s^− 1 respectively. The electrical conductivity of biopolymeric hybrid is comparable to that of commercially used synthetic conducting polymers. The ion transfer number of AgSiO₂ nanocomposites attributes the superionic character for electrical conduction.     

Effects of interstitial Li+ ions on the properties of novel Li4.08Zn0.04Si0.96O4 ceramic electrolyte

The aim of this work was to investigate the effects of interstitial ions in the novel Li_4 + 2xZn_xSi_1 − xO₄ (x = 0.04) compound prepared via sol gel method. The compound was indexed to the monoclinic unit cell in the space group P2_1/m and the chemical composition of the compound was very close to the designed composition. The introduction of two interstitial Li⁺ ions increased charge carrier concentration in the doped system resulting in an enhancement of conductivity by an order of magnitude as compared to that of the parent compound, Li₄SiO₄. The compound of Li_4.08Zn_0.04Si_0.96O₄ exhibited total conductivity values of 2.51 × 10^− 5 S cm^− 1 at ambient temperature and 3.01 × 10^− 3 S cm^− 1 at 500 °C. Ionic transference number corresponding to Li⁺ ion transport was also found to be higher than the value obtained for the parent compound. This proved that interstitial Li⁺ ions contributed to the total conductivity in the sample. Linear sweep voltammetry result showed that the Li_4.08Zn_0.04Si_0.96O₄ ceramic electrolyte was electrochemically stable up to 5.80 V versus a Li/Li⁺ reference electrode.     

Effect of solvent ratio on the properties of highly oriented sprayed fluorine-doped tin oxide thin films

Transparent conducting thin films of F:SnO₂ have been deposited onto preheated glass substrates by a spray pyrolysis technique using pentahydrate stannic chloride (SnCl₄·5H₂O) and ammonium fluoride (NH₄F) as precursors and mixture of water and propane-2-ol as solvent. The concentration of SnCl₄·5H₂O and NH₄F is kept fixed and the ratio of water and propane-2-ol solvent in the spraying solution is varied. A fine spray of the source solution using air as a carrier gas has grown films of thickness up to 995 nm. Optical absorption, X-ray diffraction, Van der Pauw technique for measurement of a sheet resistance and Hall effect measurements at room temperature for determination of carrier density and conductivity have been used. The as-deposited films are of polycrystalline SnO₂ with a tetragonal crystal structure and are preferentially having orientation along the (200) direction with texture coefficient as high as 6.16. The average grain size for the as-deposited sample is found to be of the order of 44 nm. The films have moderate optical transmission (up to 70–85% at 550 nm). The figure of merit (ϕ) values vary from 1.95 · 10^− 3 to 35.68 · 10^− 3 Ω^− 1. The films are heavily doped, degenerate and exhibit n-type electrical conductivity. The lowest sheet resistance (R_s) for the optimized sample is 5.1 Ω. The films have a resistivity of 5.43 · 10^− 4 Ω cm and mobility around 7.38 cm² V^− 1 s^− 1.     

Investigation of traps in AlGaN/GaN HEMTs by current transient spectroscopy

Deep levels in AlGaN/GaN HEMTs on Si substrate are known to be responsible for trapping processes like: threshold voltage shift, leakage current, degradation in saturation current and hysteresis effect. The related deep levels are directly characterized by Conductance Deep Level Transient Spectroscopy (CDLTS) method. Hereby we have detected four carrier traps with activation energy of 0.83, 0.50, 0.20 and 0.07 eV and capture cross-section respectively of σ = 3.14 × 10^− 14 cm², σ = 2.57 × 10^− 15 cm², σ = 3.03 × 10^− 17 cm² and σ = 2.65 × 10^− 15 cm². All these traps are located between the substrate and the two-dimensional electron gas (2DEG) channel.     

Facile electrosyntheses of high-strength and highly-conductive poly(1,12-bis(carbazolyl) dodecane) films

Homogeneous and high-strength free-standing poly(1,12-bis(carbazolyl)dodecane) film with conductivity of 1.36 S cm^− 1 and a tensile strength of 230 kg cm^− 2 was electrochemically synthesized in a novel mixed electrolyte of boron trifluoride diethyl etherate containing 40% CHCl₃ (by volume) by direct anodic oxidation of the monomer 1,12-bis(carbazolyl)dodecane). To the best of our knowledge, this is the first report that free-standing polycarbazole films with high strength and high conductivity can be electrodeposited on stainless steel sheet.     

3D Co-Doping α-Ni(OH)2 Nanosheets for Ultrastable,High-Rate Ni-Zn Battery

The α-Ni(OH)₂ is regarded as one promising cathode for aqueous nickel-zinc batteries due to its high theoretical capacity of ≈480 mAh g⁻¹, its practical deployment however suffers from the poor stability in strong alkaline solution, intrinsic low electrical conductivity as well as the retarded ionic diffusion. Herein, a 3D (three dimensional) macroporous α-Ni(OH)₂ nanosheets with Co doping is designed through a facile and easily scalable electroless plating combined with electrodeposition strategy. The unique micrometer-sized 3D pores come from Ni substrate and rich voids between Co-doping α-Ni(OH)₂ nanosheets can synergistically afford facile, interconnected ionic diffusion channels, sufficient free space for accommodating its volume changes during cycling; meanwhile, the Co-doping can stabilize the structural robustness of the α-Ni(OH)₂ in the alkaline electrolyte during cycling. Thus, the 3D α-Ni(OH)₂ shows a high capacity of 284 mAh g⁻¹ at 0.5 mA cm⁻² with an excellent retention of 78% even at 15 mA cm⁻², and more than 2000 stable cycles at 6 mA cm⁻², as well as the robust cycling upon various flexible batteries. This work provides a simple and efficient pathway to enhance the electrochemical performance of Ni-Zn batteries through improving ionic transport kinetics and stabilizing crystal structure of cathodes.     

Low-temperature synthesis of CeB6 nanowires and nanoparticles as feasible lithium-ion anode materials

Metallic CeB₆ nanomaterials were prepared via the low-temperature solution combustion method (nanoparticles) and high-pressure solid state reaction (nanowires). X-ray diffraction patterns and High-resolution transmission electron microscopy images reveal that CeB₆ nanoparticles are highly crystalline and CeB₆ nanowires are single crystals. The X-ray photoelectron spectroscopy analysis indicates that the cerium is present in the +3 and +4 mixed-valence state in CeB₆. As lithium-ion anodes, CeB₆ nanowires (nanoparticles) electrode achieves a capacity of ~531 (338) mA h g⁻¹ in the initial cycle and keeps a reversible capacity of ~225 (185) mA h g⁻¹ after 60 cycles. CeB₆ nanowires are tested for 6000 cycles at 1000 mA g⁻¹, which shows a specific capacity approaching to the capacity at 100 mA g⁻¹ in spite of fluctuation within a narrow range, and keep ~168 mA h g⁻¹ after 6000 cycles, indicating a stable cycling performance owing to the excellent metal-like conductivity of (~5.67 × 10³ S m⁻¹). The reason of capacity rising is that the reduction and oxidation levels of CeB₆ electrodes are improved after the 2nd cycle with Li⁺ insertion/extraction. Meanwhile, kinetic analysis reveals that the Li⁺ storage mechanism is mainly controlled by a surface capacitive behavior.     

Influence of W5+ ions on the optical properties of doped Bi12TiO20

There have been studied single crystals of undoped and doped Bi₁₂TiO₂₀ with two concentrations of W⁵⁺ (2.62 × 10¹⁷ cm⁻³ and 2.62 × 10¹⁸ cm⁻³). There have been obtained absorption spectra in the energy range of 10,482–15,408 cm⁻¹ by classical measurements. There have been determined the cross-section (σ_a) of the impurity absorption and the oscillator strength of d–d transitions. There have been calculated the refractive index of doped crystals and the concentration of Ti³⁺ ions in an undoped sample through an experiment.     

Microstructures and electrical properties of calcium substituted LaFeO3 as SOFC cathode

Mixed ionic and electronic conductors of La_1−xCa_xFeO_3−δ (LCF, x =0.0–0.5) have been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), dilatometry, and four-probe electrical conductivity measurements. Ca substitution on La site reduces the LaFeO₃ sinterability and the cell volume of this orthorhombic crystal. Dense samples for property studies can be sintered at 1320 °C. Nevertheless, the sintering temperature is near the decomposition temperature of LCF for those solid solutions of x ≥ 0.3. The LCF decomposition is evident when a La-poor secondary phase, not detected in XRD, was revealed in SEM micrographs of 1270 °C thermally etched samples of x ≥ 0.3. Dilatometric studies demonstrate linear increments in thermal expansion with increasing temperature in samples of x ≤ 0.2, while show strange bendings in thermal expansion curves of x = 0.4 and 0.5. The bending in thermal expansion indicates influences of the secondary phase. The TEC value of compositions of x ≤ 0.2 is between 10.8 and 11.7 × 10⁻⁶ °C⁻¹. The LCF electrical conductivity increases with the Ca content and its temperature dependence can be described by the small polaron hopping mechanism. The composition around x = 0.15 promises to be a superior cathode for SOFC since it thermally matches with 8 mol% YSZ and 10 mol% Dy, Er substituted LAMOX electrolytes and possesses electrical conductivity near 90 S cm⁻¹ at 800 °C.     

The effect of polymeric wall on the permeability of drug-loaded nanocapsules

The aim of this work was to establish a quantitative correlation between the drug permeability and the polymer concentration in the nanocapsules. Indomethacin ethyl ester-loaded nanoemulsion and nanocapsules containing poly(epsilon-caprolactone) at different concentrations (0, 2, 4, 6, 8 and 10 mg/mL) presented drug loading between 0.981 and 1.005 mg/mL, pH values from 5.0 to 5.4, particle sizes between 232 and 261 nm, polydispersity lower than 0.24 and zeta potentials from − 8.54 mV to − 11.86 mV. An alkaline hydrolysis of indomethacin ethyl ester carried out at the particle/water interface was used to simulate a sink condition of release. The number of particles in each suspension was estimated. The calculated values ranged from 5.84 × 10¹² to 6.60 × 10¹² particles cm^− 3, showing similar concentration of particles in the formulations. The diffusion was proposed as the main mechanism of the indomethacin ester release after fitting the data to the Higuchi model. Applying the Fick's first law, the calculated indomethacin ester fluxes (J) decreased from 2.20 × 10^− 7 to 1.43 × 10^− 7 mg cm^− 2 min^− 1. Then, the drug relative permeability decreased according to the increase in the polymer concentration fitting a power law.     

Physical properties of multiwalled carbon nanotubes

Multiwalled carbon nanotubes (MWNTs), which were prepared by hydrogen arc discharge, were purified by using an infrared radiation heating system. The morphology, structure, vibrational modes and crystalline perfection of purified MWNTs were investigated by using scanning electron microscopy, high-resolution transmission electron microscopy, an X-ray diffractometer and a Raman spectrometer. Moreover, the electrical conductivity of individual purified MWNTs was measured using a two-probe method using a micro manipulator system. It turned out that the MWNTs had a high degree of graphitization, an electrical conductivity of about 1.85×10³ S cm⁻¹ along the long axis, and an enormous current density of more than 10⁷ A cm⁻².     

Montmorillonite/polypyrrole nanocomposites. The effect of organic modification of clay on the chemical and electrical properties

Montmorillonite/polypyrrole (MMT/PPy) nanocomposites, with 15% mass loading of PPy, were prepared by the in situ polymerization of pyrrole in the presence of montmorillonite (MMT) or organo-modified montmorillonite (oMMT) in aqueous solutions containing an oxidant and an anionic surfactant. The morphology of MMT/PPy nanocomposites distinctly differs from that of the untreated MMT as shown by SEM. X-ray photoelectron spectroscopy showed that the MMT/PPy nanocomposite has an MMT-rich surface, whereas the oMMT/PPy nanocomposite surface has a rather organic nature. Due to the organic modification of MMT by the alkylammonium chloride, polymerization of pyrrole at the surface of oMMT is much more efficient in producing a conductive adlayer resulting in an enhancement of conductivity of the oMMT/PPy nanocomposites (1.1 S cm^− 1) compared to MMT/PPy (3.1 × 10^− 2 S cm^− 1). The difference in the behaviour of oMMT/PPy and MMT/PPy is interpreted in terms of surface energy minimization by the alkylammonium ions present at the surface of organo-modified MMT. Indeed, the dispersive contribution to the surface energy (γ_s^d), as determined by inverse gas chromatography at 150 °C, was estimated to be 34.0 mJ/m² for oMMT, much lower than the value of 216 mJ/m² determined for MMT.     

Thermal conductivity of carbon nanotube reinforced aluminum composites: A multi-scale study using object oriented finite element method

In this study, object oriented finite element method (OOF) has been utilized to compute the thermal conductivity of plasma sprayed Al-12 wt.% Si containing 10 wt.% multiwall carbon nanotubes (CNTs). The computations have been made at micro- and macro-length scales which highlight the effect of CNT dispersion on thermal conductivity. Experimentally measured values at 50 °C indicate that CNT addition reduced the thermal conductivity of Al–Si matrix from 73 W m⁻¹ K⁻¹ to 25.4 W m⁻¹ K⁻¹ which is attributed to the presence of CNT clusters. OOF calculations at micro-length scale predicted an 81% increase in the conductivity of Al–Si matrix due to presence of well dispersed CNTs inside the matrix. At larger lengths scale, the decrease in the overall conductivity is related to the extremely low conductivity of CNT clusters. Thermal conductivity of CNT clusters could be up to three orders of magnitude lower than individual CNTs. OOF computed values match well with experimental results. OOF compute thermal conductivity of Al–CNT composite is also compared with theoretical two-phase models for CNT-composites at different length scales.     

The rock salt oxide Li2MgTiO4: Type I dielectric and ionic conductor

The exploration of the Li–Ti–Mg–O system, using both sol–gel technique and solid state reaction method, allowed a new phase, Li₂MgTiO₄, with disordered rock salt structure (a = 4.159 Å) to be synthesized. The latter is shown to be a good type I dielectric material, with a relative constant of 15 at high frequency and low dielectric loss (tanδ < 10⁻³) over the temperature range −60 to 160 °C. It is also observed that the sintering temperature of this phase is strongly lowered by adopting the sol–gel technique compared to solid state reaction (1150 °C instead of 1300 °C). Finally we show that this phase exhibits cationic conductivity above 400 °C (σ_600 °C = 9 × 10⁻⁵ S cm⁻¹).