Solid State Ionics Research Papers (original) (raw)
The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt... more
The polymer electrolytes comprising blend of poly(vinyl acetate) (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO4 as a dopant are prepared by solution casting technique. The amorphous nature of the polymer–salt complex has been confirmed by XRD analysis. The DSC thermograms show two Tg's for PVAc–PMMA blend. A decrease in Tg with the LiClO4 content reveals the increase of segmental motion. Conductance spectra results are found to obey the Jonscher's power law and the maximum dc conductivity value is found to be 1.76 × 10− 3 S cm− 1 at 303 K for the blend polymer complex with 20 wt.% LiClO4, which is suitable for the Li rechargeable batteries. The conductivity–temperature plots are found to follow an Arrhenius nature. The dc conductivity is found to increase with increase of salt concentration in the blend polymer complexes.
Li and 11 B MAS-NMR Electrical and dielectric properties a b s t r a c t Nanocrystalline lithium magnesium borate (LiMgBO 3) powders were synthesized by a Pechini process. Thermal behavior of the polymeric intermediate of LiMgBO 3 sample... more
Li and 11 B MAS-NMR Electrical and dielectric properties a b s t r a c t Nanocrystalline lithium magnesium borate (LiMgBO 3) powders were synthesized by a Pechini process. Thermal behavior of the polymeric intermediate of LiMgBO 3 sample was studied by TG-DTA. Structure and the local structural coordination of the as-prepared and calcined polymeric intermediate at 750 C of LiMgBO 3 sample were investigated by FT-IR and 7 Li & 11 B magic angle spinning-nuclear magnetic resonance (MAS-NMR) measurements respectively. XRD results confirm the formation of the pure nanocrystalline monoclinic phase of the LiMgBO 3 sample prepared at 750 C. The BET surface area of the calcined polymeric intermediate of LiMgBO 3 sample is found to be 60.48 m 2 g-1. The observed SEM mi-crographs of the LiMgBO 3 sample showed the formation of agglomerated sheet-like morphology particles and the existence of Mg and O elements in LiMgBO 3 are confirmed from the SEM-EDX spectral result. The band gap energy of LiMgBO 3 sample is evaluated and it was found to be 3.64 eV. From the analysis of the measured impedance data, at different frequencies and temperatures, the evaluated electrical conductivity of LiMgBO 3 sample was found to be 9.706 Â 10 À5 S cm À1 at 200 C. From the temperature dependence of conductivity (log sT vs. 1000/T) plot of the LiMgBO 3 sample, the evaluated activation energy (E a) for the migration of the charge carrier was found to be 0.62 eV. The measured impedance data and the LiMgBO 3 sample pellet dimensions were used for calculating AC conductivity (s ac), dielectric (ε 0 , ε 00 , tan d), electric modulus (M 0 and M 00) data and were analyzed to find out the electrical and dielectric properties of the LiMgBO 3 sample.
- by Leif Holmlid and +1
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- Materials Engineering, Condensed Matter Physics, Kinetics, Chromium
A conductivity relaxation experiment has been conducted on an SrFeCo0.5Ox sample by abruptly changing the oxygen partial pressure in the atmosphere and monitoring the change of conductivity as a function of time. The re-equilibrium... more
A conductivity relaxation experiment has been conducted on an SrFeCo0.5Ox sample by abruptly changing the oxygen partial pressure in the atmosphere and monitoring the change of conductivity as a function of time. The re-equilibrium process obeys Fick's second law. By fitting the relaxation data to the solution of the diffusion equation with appropriate boundary conditions, we could determine the oxygen chemical diffusion coefficient and the activation energy. The oxygen diffusion coefficient is 8.9 × 10−7 cm2/s at 900 °C and it increases with increase in temperature. Measured activation energy is 0.92 eV, which is slightly lower than that of other oxides in the system SrFe1 − xCoxOy.
... suggested by Barsoukov et al. [4], they were able to simulate the impedance response of an insertion electrode in a LiB cell by imposing the condition of a small voltage perturbation on the cell over a range of frequencies in MATLAB.... more
... suggested by Barsoukov et al. [4], they were able to simulate the impedance response of an insertion electrode in a LiB cell by imposing the condition of a small voltage perturbation on the cell over a range of frequencies in MATLAB. ...
Ancient to modern glass used for stained glass windows, representative of the main composition types (Ca-rich, Na- and Ca-rich and K-rich) were treated with boiling concentrated H2SO4 (338 °C) and/or in molten NaOH (320 °C, with or... more
Ancient to modern glass used for stained glass windows, representative of the main composition types (Ca-rich, Na- and Ca-rich and K-rich) were treated with boiling concentrated H2SO4 (338 °C) and/or in molten NaOH (320 °C, with or without water addition). Subsequent annealings in air or in molten KNO3 (334 °C) were also performed. Microstructures and corrosion habits were analysed by optical microscopy. Modifications of the silicate network and corrosion products were studied by Raman and IR spectroscopies, dilatometry, microhardness, and TGA. Only K-rich silicate glasses are drastically modified by concentrated sulphuric acid. The alkali leaching takes place in three steps: i) K+–H+ (not H3O+) exchange, partly reversible, inducing glass contraction and cracking, ii) a complete, irreversible H+/K+ ion exchange, iii) a (small) hydration of the formed porous, multicracked lixiviated silica-rich solid crust. The thermal treatment of the crust induces a water loss (~0.6 wt.% at