Green electrolytes based on dextran-chitosan blend and the effect of NH<Subscript>4</Subscript>SCN as proton provider on the electrical response studies

Dextran-chitosan blend added with ammonium thiocyanate (NH₄SCN)-based solid polymer electrolytes are prepared by solution cast method. The interaction between the components of the electrolyte is verified by Fourier transform infrared (FTIR) analysis. The blend of 40 wt% dextran-60 wt% chitosan is found to be the most amorphous ratio. The room temperature conductivity of undoped 40 wt% dextran-60 wt% chitosan blend film is identified to be (3.84?±?0.97)?×?10^?10 S cm^?1. The inclusion of 40 wt.% NH₄SCN to the polymer blend has optimized the room temperature conductivity up (1.28?±?0.43)?×?10^?4 S cm^?1. Result from X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis shows that the electrolyte with the highest conductivity value has the lowest degree of crystallinity (χ _c) and the glass transition temperature (T _g), respectively. Temperature-dependence of conductivity follows Arrhenius theory. From transport analysis, the conductivity is noticed to be influenced by the mobility (μ) and number density (n) of ions. Conductivity trend is further verified by field emission scanning electron microscopy (FESEM) and dielectric results.     

Evaluation of carbon-supported copper phthalocyanine (CuPc/C) as a cathode catalyst for fuel cells using Nafion as an electrolyte

Carbon-supported copper phthalocyanine (CuPc/C) nanoclusters, as a novel suitable cathode catalyst in polymer electrolyte membrane fuel cells, have been synthesized via a combined solvent impregnation and milling procedure along with high-temperature treatment. For optimizing the electrocatalytic activity of the catalyst obtained, the electrode with varying Nafion ionomer contents in the catalyst layer was screened by cyclic voltammetry and linear sweep voltammetry employing a rotating disk electrode technique to investigate the effect of Nafion ionomer as for alkaline electrolyte. For comparative purposes, electrode with various contents of available anion-ionomer was also investigated. The results revealed that the content of Nafion ionomer can affect the oxygen reduction reaction activity of the CuPc/C catalyst and an optimal content of Nafion ionomer was around 3.5?×?10¹?μg?cm^?2, which corresponds well with the electrode prepared using available anion-ionomer. The electrode prepared using Nafion ionomer can produce a comparable performance to that of using available anion-ionomer, giving an onset potential at 0.1 V with a half-wave potential of ?0.03 V. Furthermore, Koutechy–Levich analysis showed that the value of electron transfer number is in the range of 3.40 to 3.74 when using electrode with varying Nafion ionomer contents from 2.5?×?10¹ to 1.6?×?10²?μg?cm^?2. The membrane electrode assembly fabricated with the CuPc/C cathode catalyst with a loading of 3.6 mg?cm^?2 and a Nafion membrane immersed in 3 M KOH for 48 h produced a power density of 3.8 mW?cm^?2 at room temperature.     

Electrical properties of proton conducting solid biopolymer electrolytes based on starch–chitosan blend

Two systems (salted and plasticized) of starch–chitosan blend-based electrolytes incorporated with ammonium chloride (NH₄Cl) are prepared via solution cast technique. The incorporation of 25 wt% NH₄Cl has maximized the room temperature conductivity of the electrolyte to (6.47?±?1.30)?×?10^?7 S cm^?1. Conductivity is enhanced to (5.11?±?1.60)?×?10^?4 S cm^?1 on addition of 35 wt% glycerol. The temperature dependence of conductivity for all electrolytes is Arrhenian, and the value of activation energy (E _a ) decreases with increasing conductivity. Conductivity is found to be influenced by the number density (n) and mobility (μ) of ions. The complexation between the electrolytes components is proven by Fourier transform infrared analysis. The relaxation time (t _r ) for selected electrolytes is found to decrease with increasing conductivity and temperature. Conduction mechanism for the highest conducting electrolyte in salted and plasticized systems is determined by employing Jonscher’s universal power law.     

The effect of NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> towards the conductivity enhancement and electrical behavior in methyl cellulose-starch blend based ionic conductors

Solid polymer electrolytes based on methyl cellulose (MC)-potato starch (PS) blend doped with ammonium nitrate (NH₄NO₃) are prepared by solution cast technique. The interaction between the electrolyte’s materials is proven by Fourier transform infrared (FTIR) analysis. The thermal stability of the electrolytes is obtained from thermogravimetric analysis (TGA). The room temperature conductivity of undoped 60 wt.% MC-40 wt.% PS blend film is identified to be (1.04 ± 0.19) × 10^?11 S cm^?1. The addition of 30 wt.% NH₄NO₃ to the polymer blend has optimized the room temperature conductivity to (4.37 ± 0.16) × 10^?5 S cm^?1. Conductivity trend is verified by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and dielectric analysis. Temperature-dependence of conductivity obeys Arrhenius rule. Conductivity is found to be influenced by the number density (n) and mobility (μ) of ions. From transference number measurements (TNM), ions are found to be the dominant charge carriers.     

Optical investigation of DyFeO3

Optical absorption spectra of DyFeO₃ have been investigated at 1.2≦T≦4.2 °K, andT=77 °K From the temperature dependent lineshift a Néel temperature ofT _N=(3.8±0.5) °K is deduced for the dysprosium sublattices. The groundstate splitting due to the iron-dysprosium interactions is about 1.5 cm^?1 and due to the dysprosiumdysprosium interactions (5.0±1.4) cm^?1. Zeeman studies give the magnetic moment of the dysprosium ions asμ=(9.2±1.0)μ _B.     

Optical investigation of HoFeO3

The absorption spectra of HoFeO₃ were investigated in the near infrared spectral region at temperatures of 1.2, 4.2, 20 and 77 °K respectively. At every temperatureT≦20 °K all the absorption lines show the same splitting which is attributed to the groundstate; this splitting is (7.2±0.5) cm^?1 at 20 °K and decreases to (4.9±0.8) cm^?1 extrapolated to 0 °K. From these splittings the holmium-iron and the holmiumholmium interactions can be deduced. Measurements with an external magnetic field yield a magnetic moment ofμ=(7.6±0.7)μ _B per holmium ion. The moments are directed at angles of ?28° and ?152° with respect to theb-axis.     

Chemical bath deposition of CdS channel layer for fabrication of low temperature-processed thin-film-transistors

～66 nm thick CdS film with a hexagonal structure was uniformly generated via a low temperature-processed chemical bath deposition at 80 °C using a complexing agent of ethylenediaminetetraacetic acid and its crystal structure, surface morphology, optical transmittance, and Raman scattering property were measured. Grown CdS film was used as a channel layer for the fabrication of bottom-gate, top-contact thin-film-transistor (TFT). The TFT device with 60 °C-dried channel layer exhibited a poor electrical performance of on-to-off drain current ratio (I_on/I_off) of 5.1 × 10³ and saturated channel mobility (μ_sat) of 0.10 cm²/Vs. However, upon annealing at 350 °C, substantially improved electrical characteristics resulted, showing I_on/I_off of 5.9 × 10⁷ and μ_sat of 5.07 cm²/Vs. Furthermore, CdS channel layer was chemically deposited in an identical way on a transparent substrate of SiN_x/ITO/glass as part of transparent TFT fabrication, resulting in I_on/I_off of 5.8 × 10⁷ and μ_sat of 2.50 cm²/Vs.     

Influence of the annealing technique on the properties of Li ion-conductive Li1.3Al0.3Ti1.7(PO4)3 films

Li_1.3Al_0.3Ti_1.7(PO₄)₃ films were comparatively prepared by rapid thermal annealing (RTA) and conventional furnace annealing(CFA). The phase identification and surface morphology of the prepared films were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical window, ionic conductivity, activation energy, and electronic conductivity were conducted by cyclic voltammetry, electrochemical impedance spectroscopy, and four-probe technique. The results show that the films prepared by RTA and CFA are homogenous and crack-free. The film prepared by RTA shows smaller grains and is denser than the one prepared by CFA. The electrochemical windows of the two films are beyond 2.4 V. The ionic conductivities of the films prepared by RTA and CFA are 2.7?×?10^?6 S cm^?1 and 1.4?×?10^?6 S cm^?1, respectively. The activation energy of the film prepared by RTA is 0.431 eV, which is slightly smaller than the one prepared by CFA. The electronic conductivity of the two films is about 10^?10 S cm^?1.     

EPR of Cu2+ Impurities in Cytosine Hydrochloride: A Case of Superhyperfine Structure

Electron paramagnetic resonance spectra of Cu²⁺ impurities in cytosine hydrochloride single crystals are observed at liquid nitrogen temperature. Two magnetically equivalent sites for Cu²⁺ have been observed. The parameters of ⁶³Cu obtained with the fitting of spectra to rhombic symmetry spin Hamiltonian are: g _x  = 2.047 ± 0.002, g _y  = 2.187 ± 0.002, g _z  = 2.390 ± 0.002, A _x  = (86 ± 3) × 10^?4 cm^?1, A _y  = (87 ± 3) × 10^?4 cm^?1, and A _z  = (138 ± 3) × 10^?4 cm^?1. The observed bands in optical spectra of the single crystal recorded at room temperature are assigned to various d–d and charge-transfer transitions. Using both EPR and optical data, the nature of bonding of metal ion with different ligands is discussed.     

Mechanistic Insights into the Inhibition of Endo-β 1,4 Xyloglucan Hydrolase by a Classical Aspartic Protease Inhibitor

This is the first report of inactivation of xyloglucanase from Thermomonospora sp by pepstatin A, a specific inhibitor towards aspartic proteases. The steady state kinetics revealed a reversible, competitive, two-step inhibition mechanism with IC ₅₀ and K _i values of 3.5?±?0.5 μM and 1.25?±?0.5 μM respectively. The rate constants determined for the isomerization of EI to EI^* and the dissociation of EI* were 14.5?±?1.5?×?10^?5?s^?1 and 2.85?±?1.2?×?10^?8?s^?1 respectively, whereas the overall inhibition constant K _i ^* was 27?±?1 nM. The conformational changes induced upon inhibitor binding to xyloglucanase were monitored by fluorescence analysis and the rate constants derived were in agreement with the kinetic data. The abolished isoindole fluorescence of o-phthalaldehyde (OPTA)-labeled xyloglucanase and far UV analysis suggested that pepstatin binds to the active site of the enzyme. Our results revealed that the inactivation of xyloglucanase is due to the interference in the electronic microenvironment and disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis.     

Growth of high-quality ZnO thin films on (11\bar{2}0) a-plane sapphire substrates by plasma-assisted molecular beam epitaxy

High-quality ZnO thin films were grown on a-plane sapphire substrates by plasma-assisted molecular beam epitaxy. X-ray diffraction and transmission electron microscopy reveal that the ZnO films have high structural quality and an atomically sharp ZnO/Al₂O₃ interface. The full width at half maximum values of the 0002 and $30\bar{3}2$ ZnO ω-rocking curves are 467.8 and 813.5 arc sec for a 600 nm thick ZnO film. A screw dislocation density of 4.35×10⁸ cm^?2 and an edge dislocation density of 3.38×10⁹ cm^?2 are estimated by X-ray diffraction. The surface of the ZnO epilayers contains hexagonal pits, which can be observed in the Zn-polar ZnO. The films have a resistivity of 0.119 Ω?cm, an electron concentration of 6.85×10¹⁷ cm^?3, and a mobility of 76.5 cm²?V^?1?s^?1 at room temperature. Low temperature photoluminescence measurements show good optical properties comparable to ZnO single crystals.     

Ferroelectric and optical properties of Ba6Ti2Nb8O30 single crystals

The dielectric, optical and non-linear optical properties of Ba₆Ti₂Nb₈O₃₀ single crystals were examined from room temperature up to the Curie temperature of 245°C. The spontaneous polarization at room temperature was estimated as 0·22±0·01 C/m². The linear electrooptic constants were measured as r₃₃^T=(1·17±0·02)×10^?10 and r₁₃^T=(0·42±0·01)×10^?10 m/V. The non-linear optical coefficients were d₃₃=(15·1±2·0)×10^?12 and d₃₁=(11·0±2·0)×10^?12 m/V, which are comparable to those of Ba₄Na₂Nb₁₀O₃₀. Temperature dependences of δ₃₃ and δ₃₁ (Miller's δ) were found to be proportional to that of P_s.     

Relaxation des Natrium-Grundzustandes bei Stößen mit den stabilen Helium- und Wasserstoff-Isotopen

The spin-polarization of the optically pumped Na-groundstate is investigated in presence of the stable He- and H₂-isotopes. The following disorientation cross sections are derived from the pressure dependence of the relaxation rate:σ=(16.2±2.0) · 10^?26 cm² for He³ σ=(2.4±0.5) · 10^?26 cm² for He⁴ σ=(3.9±1.5) · 10^?26 cm² for H₂ σ=(2.3±1.0) · 10^?26 cm² for D₂. These values can be compared with theoretical cross sections based on two relaxation models and indicate the existence of a relaxation mechanism involving the exchange of the electronic alkali-spin with the nuclear spin of the foreign gas.     

Neutrino-induced deuteron disintegration in an experiment at the Krasnoyarsk nuclear reactor

The results of studying antineutrino interactions with deuterons (CCD and NCD reactions) and hydrogen (CCP) at the Krasnoyarsk underground reactor with the Deuteron detector are presented. The cross sections for NCD and CCD were measured with a precision of 9%. For CCP, the precision is 3%: σ _expt ^NCD =(3.35±0.31)×10^?44 cm²/fission ²³⁵U, σ _expt ^NCD =(1.08±0.09)×10^?44 cm²/fission ²³⁵U, and σ _expt ^NCD =(6.39±0.19)×10^?43 cm²/fission ²³⁵U. The precision of the experimental results is close to the theoretical one and is in good agreement with other experiments. The limit on the parameters of antineutrino oscillations into the sterile state was obtained: Δm ²≤4.7×10^?2 eV² for sin²(2?)=1.0 (68% C.L.). A comparison of the measured and theoretical cross section gives us the neutron-neutron scattering length of a _nn(S)=?17±6 fm in the approach of zero momentum transfers. The weak neutral current constant is in good agreement with the prediction of the Standard Model: G _A ^NC =G _A ^CC /0.932±0.056.     

Influence of differential stress on the galvanic interaction of pyrite–chalcopyrite

The effect of stress action on pyrite–chalcopyrite galvanic corrosion was investigated using polarization curves and electrochemical impedance spectroscopy (EIS) measurements. When stress increased from 0 to 4?×?10⁵ Pa, the corrosion current density of pyrite–chalcopyrite increased from 5.678 to 6.719 μA cm^?2, and the corrosion potential decreased from 281.634 to 270.187 mV, accompanied by a decrease in polarization resistance from 25.09 to 23.79 Ω·cm². EIS results show there have three time constants in the Nyquist diagrams, which indicated the presence of different steps during the corrosion process. Stress dramatically enhanced pyrite–chalcopyrite galvanic corrosion by affecting the Cu_1???x Fe_1???y S₂ film and the double layer, whereas had little impact on the adsorption species. When the stress changed from 0 to 4?×?10⁵ Pa, the pore resistance and capacitance of the Cu_1???x Fe_1???y S₂ film, R _p and Q _p, changed by 25.72 and 72.28 %, respectively. The adsorption species resistance, R _sl, and capacitance, Q _sl, only changed by 9.77 and 2.31 %, respectively.     

Characterization of SiON/InP MOS structure with sulfidation, fluorination, and hydrogenation

Liquid phase deposited SiON film on InP with (NH₄)₂S treatment shows superior electrical characteristics due to the reduction of native oxides and sulfur passivation. Simultaneously, HF in SiON liquid phase deposition solution can effectively reduce residual native oxides on InP and provide fluorine passivation in SiON/InP film and interface. With post-metallization annealing (PMA), hydrogen ions can further passivate defects in SiON/InP film and interface. With these treatments, the PMA-LPD-SiON/(NH₄)₂S-treated InP MOS structure shows excellent electrical characteristics. With the physical thickness of 5.4 nm, the leakage current densities can be as low as 1.25×10^?7 and 6.24×10^?7 A/cm² at ±2 V, and the interface state density is 3.25×10¹¹ cm^?2?eV^?1.     

Effect of NH4I and I2 concentration on agar gel polymer electrolyte properties for a dye-sensitized solar cell

Gel polymer electrolytes were prepared using agar polymer host, NH₄I, and I₂ salts. The sample of agar paste with 1.0 M of NH₄I and 0.2 μM of I₂ exhibits the highest conductivity and lowest viscosity values at room temperature of (2.64?±?0.19)?×?10^?3?S?cm^?1 and 1.17?±?0.29 Pa?s, respectively. All of the gel polymer electrolytes display Arrhenian behavior, and the optimum agar paste gave the lowest activation energy of 0.25 eV. It also had a good physical appearance compared with the other samples. This gel polymer electrolyte had a good potential and was applicable to a role as electrolyte in ITO-ZnO (N719 dye)/agar paste?+?1.0 M NH₄I?+?0.2 μM I₂/Au-Pd-ITO dye-sensitized solar cell.     

The effect of LiCF<Subscript>3</Subscript>SO<Subscript>3</Subscript> on the complexation with potato starch-chitosan blend polymer electrolytes

This work examines the effect of lithium trifluoromethanesulfonate (LiCF₃SO₃) and glycerol on the conductivity and dielectric properties of potato starch-chitosan blend-based electrolytes. The electrolytes are prepared via solution cast technique. From X-ray diffraction (XRD) analysis, the blend of 50 wt.% starch and 50 wt.% chitosan is found to be the most amorphous blend. Fourier transform infrared (FTIR) spectroscopy studies show the interaction between the electrolyte materials. The room temperature conductivity of pure starch-chitosan film is found to be (2.85 ± 1.31) × 10^?10 S cm^?1. The incorporation of 45 wt.% LiCF₃SO₃ increases the conductivity to (7.65 ± 2.27) × 10^?5 S cm^?1. Further conductivity enhancement up to (1.32 ± 0.35) × 10^?3 S cm^?1 has been observed on addition of 30 wt.% glycerol. This trend in conductivity is verified by XRD and dielectric analysis. The temperature dependence of conductivity of all electrolytes are Arrhenian.     

Li+ transportation kinetics of FeF3 · 0.33H2O/C nanocomposite synthesized by one-step solid state method

A new cathode material for lithium ion battery FeF₃?·?0.33H₂O/C was synthesized successfully by a simple one-step chemico-mechanical method. It showed a noticeable initial discharge capacity of 233.9 mAh g^?1 and corresponding charge capacity of 186.4 mAh g^?1. A reversible capacity of ca.157.4 mAh g^?1 at 20 mA g^?1 can be obtained after 50 charge/discharge cycles. To elucidate the lithium ion transportation in the cathode material, the methods of electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) were applied to obtain the lithium diffusion coefficients of the material. Within the voltage level of 2.05–3.18 V, the method of EIS showed that \( {D}_{{\mathrm{Li}}^{+}} \) varied in the range of 1.2?×?10^?13?~?3.6?×?10^?14 cm² s^?1 with a maximum of 1.2?×?10^?13 cm² s^?1 at 2.5 V. The method of GITT gave a result of 8.1?×?10^?14?~?1.2?×?10^?15 cm² s^?1. The way and the range of the variation for lithium ion diffusion coefficients measured by the GITT method show close similarity with those obtained by the EIS method. Besides, they both reached their maximum at a voltage level of 2.5 V.     

Optimization of pulsed laser deposited ZnO thin-film growth parameters for thin-film transistors (TFT) application

In this work we present the optimization of zinc oxide (ZnO) film properties for a thin-film transistor (TFT) application. Thin films, 50±10 nm, of ZnO were deposited by Pulsed Laser Deposition (PLD) under a variety of growth conditions. The oxygen pressure, laser fluence, substrate temperature and annealing conditions were varied as a part of this study. Mobility and carrier concentration were the focus of the optimization. While room-temperature ZnO growths followed by air and oxygen annealing showed improvement in the (002) phase formation with a carrier concentration in the order of 10¹⁷–10¹⁸/cm³ with low mobility in the range of 0.01–0.1 cm²/V?s, a Hall mobility of 8 cm²/V?s and a carrier concentration of 5×10¹⁴/cm³ have been achieved on a relatively low temperature growth (250 °C) of ZnO. The low carrier concentration indicates that the number of defects have been reduced by a magnitude of nearly a 1000 as compared to the room-temperature annealed growths. Also, it was very clearly seen that for the (002) oriented films of ZnO a high mobility film is achieved.