SAXS/DSC/WAXD study of TiO 2 nanoparticles and the effect of γ-radiation on nanopolymer electrolyte (original) (raw)
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SAXS/WAXS/DSC study of temperature evolution in nanopolymer electrolyte
Vacuum, 2009
Electrolytes as nanostructured materials are very attractive for batteries or other types of electronic devices. (PEO) 8 ZnCl 2 polymer electrolytes and nanocomposites (PEO) 8 ZnCl 2 /TiO 2 were prepared from PEO and ZnCl 2 and with addition of TiO 2 nanograins. The influence of TiO 2 nanograins was studied by small-angle X-ray scattering (SAXS) simultaneously recorded with wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) at the synchrotron ELETTRA. It was shown by previous impedance spectroscopy (IS) that the room temperature conductivity of nanocomposite polymer electrolyte increased more than two times above 65°C, relative to pure composites of PEO and salts. The SAXS/DSC measurements yielded insight into the temperature-dependent changes of the grains of the electrolyte as well as to differences due to different heating and cooling rates. The crystal structure and temperatures of melting and crystallization of the nanosize grains was revealed by the simultaneous WAXS measurements.
Radiation modification of (PEO) 8ZnCl 2 polyelectrolyte and nanocomposite
Solid State Ionics, 2005
(PEO)8ZnCl2 polyelectrolytes and nanocomposites were prepared using PEO γ-irradiated to selected doses and TiO2 nanograins and were studied by impedance spectroscopy, DSC, optical microscopy and FTIR. Room-temperature conductivity increase up to two orders of magnitude was achieved. The crystallinity significantly decreased with radiation dose increase due to crosslinking of PEO. Addition of nanograins caused an increase in conductivity to a significantly larger extent than can be ascribed to crystallinity, possibly because of interactions of anion with nanograins.
Radiation modification of (PEO)ZnCl polyelectrolyte and nanocomposite
Solid State Ionics, 2005
PEO) 8 ZnCl 2 polyelectrolytes and nanocomposites were prepared using PEO g-irradiated to selected doses and TiO 2 nanograins and were studied by impedance spectroscopy, DSC, optical microscopy and FTIR. Room-temperature conductivity increase up to two orders of magnitude was achieved. The crystallinity significantly decreased with radiation dose increase due to crosslinking of PEO. Addition of nanograins caused an increase in conductivity to a significantly larger extent than can be ascribed to crystallinity, possibly because of interactions of anion with nanograins. D
Vibrational study of the crystalline phases in (PEO)8ZnCl2 nanocomposite electrolyte
Vacuum, 2005
The ability of poly(ethylene oxide) (PEO) to form crystalline complexes with a variety of salts has provided a number of novel compounds in which to examine fundamental questions of structure, coordination and transport properties. In this work we study electrolyte from polymer-salt compounds based on ZnCl 2. Polymer electrolyte (PEO) 8 ZnCl 2 has been prepared by the sol-gel procedure. Nanocomposite polymer electrolyte was formed by adding 25-nm-sized TiO 2 grains during the preparation procedure. The influence of added nanosize TiO 2 grains to polymer electrolyte was studied by comparative impedance and vibrational spectroscopic studies of IR and Raman measurements.
Polymer bulletin , 2022
Highly conductive and stable solid polymer electrolytes (SPEs) will make a dramatic impact on electrochemical applications. This paper reports the electron beam (EB) induced modifications of structural, electrical and electrochemical properties of poly (ethylene oxide)-based SPEs. FT-IR and SEM characterizations confirm the structural rearrangements and crystallinity reduction in irradiated films due to degradation effects. The electrical and dielectric studies imply that dielectric permittivity (ε), and conductivity values increased after irradiation. The intensity of the well-defined relaxation peaks (tanδ) increased and also, the peak position is shifted toward the higher frequency with dose is attributed to increase in mobile charge carriers density or dipolar molecules formed in the irradiated films. The amorphocity of the films increases with radiation dose due to scissoring and cross-linking of polymer chains. At room temperature, the ionic conductivity of the non-irradiated sample is ~ 1.55310 −5 Scm −1 and increases with dose, reaching a maximum value of ~ 3.4 × 10 −4 Scm −1 for 100 kGy. The Cyclic Voltammetry study confirms that the modified polymer electrolyte film shows the ideal capacitive behavior and specific capacitance values significantly improved after EB irradiation due to a high-surfacearea and increase in the charge carrier concentration. Hence, these modified polymer electrolyte films are a promising material for battery, supercapacitor, and fuel cell applications.
The physical and chemical properties of gamma ray irradiated polymer electrolyte films
The physical and chemical properties of Gamma ray irradiated polymer electrolyte (PEO-CdCl2) films have been investigated. The FT-IR result evidenced the degradation due to chain scission/cross linking in the irradiated films. The DSC and TGA results show that thermal stability and crystallinity are significantly decreased in irradiated films. The optical micrograph image shows the size of spherulite structure and surface roughness found to be decreased with increasing the irradiation dose. The increase in the optical absorption and shifts toward higher wavelength side was observed in the irradiated film. Also optical band gaps (Eg), Urbach energy is estimated and found to be decreased, meanwhile the number of carbon atoms in cluster increased with the dose. The changes of dielectric permittivity, AC conductivity and optical band gap after irradiation were attributed due to degradation. The high conductivity of 1.156 × 10−4Scm−1 observed in the 150 kGy irradiated film; it was about to order magnitudes higher than that of non-irradiated film. The electric modulus results were depicts the relaxation time (τ) found decreased and broadening of peaks signifies it is the Non-Debye relaxation behavior. These obtained results reveal that there is a possibility of improving physical properties polymer electrolyte and it may open up various opportunities to use these materials in different applications.
Conductivity Modulation in Polymer Electrolytes and their Composites by Ion Beam Irradiation
Polymers are a class of materials widely used in different fields of applications. With imminent applications of polymers, the study of radiation induced changes in polymers has become an obvious scientific demand. The bombardment by ion beam radiations has become one of the most promising techniques in present day polymer research. When the polymers are irradiated, a variety of physical and chemical changes takes place due to energy deposition of the radiation in the polymer matrix. Scissoring, cross-linking, recombination, radical decomposition, etc. are some of the interesting changes that are obvious in polymers. The modification in polymer properties by irradiation depends mainly on the nature of radiation and the type of polymer used. Polymer electrolytes are obtained by modifying polymers by doping, complexing, or other chemical processes. In general, they suffer from low conductivity due to high crystallinity of the matrix. The effect of radiation on polymer electrolyte is expected to alter their crystalline nature vis-a-vis electrical properties. This review article shall elaborate modifications in the physical and chemical properties of polymer electrolytes and their composites. The variations in properties have been explored on PEO based polymer electrolyte and correlated with the parameters responsible for such changes. Also a comparison with different types of the polymers irradiated with a wide range of ion beams has been established.
NMR and conductivity study of PEO-based composite polymer electrolytes
The influence of the space charge created by the presence of TiO 2 nanoparticles on the lithium and polymer chain mobility have been investigated in solid composite polymer electrolytes (CPE), poly(ethylene oxide) (PEO) LiClO 4 , by using complex impedance spectroscopy and nuclear magnetic resonance (NMR). Special care was taken with the synthesis and the characterization of the TiO 2 particles and with the composite preparation. The conductivity and NMR measurements were undertaken in composite samples nanoparticles having constant total surface area. Proton ( 1 H) and lithium ( 7 Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. Activation energies extracted from the 7 Li relaxation data are in the range 0.20 Á/0.22 eV. The NMR decoupling experiment suggests that the Li Á/Li interactions are stronger in the composites when compared with those of the ceramic free electrolytes. #
Effect of gamma irradiation on the polymer electrolyte PEO-NH 4 ClO 4
Ionics, 2008
Irradiation affects the structures of materials at different scales, thus changing physical and chemical properties. We study here the effect of gamma irradiation at different doses on the polymer electrolyte PEO-NH4ClO4. Optical micrographs show cracks in the irradiated samples and impedance spectroscopy measurements indicate reduced ion-conductivity at room temperature but slight enhancement at higher temperature. At high frequencies, the real part of the admittance shows a power-law variation; the exponent, which is a measure of self-similarity of the structure, is reduced on irradiation. The overall results point to a more disordered structure at higher radiation doses.