Papers by Keyword: Ion Conductivity

Abstract: Sulfonated graphene oxide (sGO) was used as a filler to enhance performance of sulfonated poly(ether ether ketone)(sPEEK) membrane. The sGO was firstly prepared by treating graphene oxides (GO) with sulfanilic acid at 70 °C for 20 h. The sGO was characterized by FTIR and XPS techniques. Composite membranes of various amount of sGO were fabricated via solution casting method. The properties of composite membranes were investigated by measuring ion exchange capacity (IEC), water uptake, ion conductivity and vanadium ion permeability. From the results, it was found that the IEC and water uptake of the membranes increased after adding the sGO. Ion conductivity of the sPEEK membrane also increased from 8.94*10^-3 Scm^-1 to 10.55*10^-3 Scm^-1. Moreover, permeability of vanadyl sulfate (VOSO₄) through the composite membranes were decreased. These composite membranes exhibit great potential for vanadium redox flow batteries application.

Abstract: The relationship between the optical phonon parameters and the oxygen ion conductivities were investigated for AlYb co-doped zirconia ceramics. Intrinsic intragrain ion conductivity, σ_dc, decreased with increasing Al loading into ytterbia-stabilized zirconia, while the damping parameter of the lattice vibration, γ_1TO, increased. This phenomenon agreed with findings of our previous study, which revealed a relationship between the σ_dc and the γ_1TO for zirconia-based ion conductors.

Abstract: Thin films of poly (ethylene oxide) (PEO), poly (methyl methacrylate) (PMMA) and selected blends of PEO/PMMA with and without the addition of LiClO₄ were prepared using solution casting technique. The presence of a single T_g which corresponds closely to that of the Gordon Taylor equation confirms the miscibility of both the salt-free and salt-doped blends. The T_gs and the ion conductivity (σ) at room temperature of PEO, PMMA and the PEO/PMMA blends generally increase with ascending salt concentration (Y). Variations in the σ value as a function of Y for all the three systems correlate closely with their respective T_g results. PMMA-salt complex records the lowest σ value at all salt concentrations. PEO/PMMA/LiClO₄ blend with 75 wt% PEO exhibits the highest σ value of 5 x 10^-7 S cm^-1 at Y = 0.10. The σ value of the blend-salt system is observed to be slightly lower than that of the PEO-salt system. This is due to reduced segmental motion cause by increased T_g of the blend and a decrease in free ions in the amorphous phase of PEO as a small amount of the salt is solvated by PMMA in the blend. Therefore, the percolation path lies in the amorphous PEO rich phase of the blend.

Abstract: In CeO₂-based solid electrolytes, it has been shown that point defects are directly responsible for oxygen ionic conduction. The ionic conductivity is strongly affected by the anion vacancy concentration which is enhanced by doping with aliovalent cations. When rare earth sesquioxides such as La₂O₃, Gd₂O₃, Sm₂O₃, Y₂O₃ are added to CeO₂, the dopant cation substitutes for the cerium ion, and oxygen vacancies are created for charge compensation. Incorporation of trivalent dopants into CeO₂ at the Ce⁴⁺ sites can be depicted by the following defect reaction (expressed in Kröger-Vink notation):

Abstract: We have presented general ideas to develop a theoretical methodology, based on Molecular simulation and Einstein equation aimed to describe the mechanism and behavior of chitosan-membrane ion conductivity and to obtain its magnitude for different ionic species. Atomistic molecular modelling has been utilized to construct an ionic-conducting polymer electrolyte system consisting of poly(chitosan), H O 2 molecules, and + H O 3 , − OH , 2− 4 SO ions, inside of the simulation cell. The COMPASS force field was used. The simulation allows describing the mechanism of ionic conductivity along the polymer matrix. The theoretical results obtained are compared with previously-reported experimental data for chitosan membranes. The present methodology can be considered as a first step towards understanding these complex problems of technological interest.

Abstract: The total conductivity and oxygen deficiency of partially substituted strontium ferrite, SrFe0.9M0.1O3-δ (M=Cr, Ti, Al), at 700-950°C were measured depending on oxygen partial pressure varying in ranges 10-19-0.5 and 10-5-0.5 atm. The partial contributions of n- and p-type electronic charge carriers and oxygen ions to the electrical transport were determined analyzing the total conductivity vs. oxygen pressure dependencies. Additions of all dopants studied in this work are found to extend the cubic perovskite phase stability range and to improve oxygen transport in the intermediate-temperature range. The behavior of hole mobility suggests a polaron conduction mechanism. Doping with aluminum has a weak influence on the mobility level, while the incorporation of Cr and Ti cations into the ferrite lattice decreases hole mobility up to four times.