Browsing by Author "R. Roshan"

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Effect of Li3+ ion irradiation on ionic transport properties of complexed polymer electrolytes
(Materials Research Society, 2010) P.N. Gupta; G.K. Prajapati; R. Roshan
Swift heavy ion (SHI) irradiation effects on ionic conduction in the PVA-H3PO4 polymer electrolyte films have been investigated due to its variety of applications in electrochemical devices. Polymer electrolytes films are irradiated with 50 MeV Li3+ ions having five different fluences viz. 5×1010, 1011, 5×1011, 1012 and 5×1012 ions/cm2. It is observed that irradiation of the polymer electrolyte films with swift heavy ions shows enhancement in conductivity at lower fluences and decrease in conductivity at higher fluences. It appears that below the critical fluence, swift heavy ion irradiation increases the diffusivity of Li+ ion in the polymer electrolyte which provides larger pathways for ionic transport throughout the system. The temperature dependence of electrical conductivity variation has been used to compute the activation energy involved in conduction process. © 2010 Materials Research Society.
Effect of nanoparticles on complexed polymer electrolytes
(Apple Academic Press, 2012) P.N. Gupta; G.K. Prajapati; R. Roshan
Thin films of Nano-Composite Polymer Electrolyte (NCPE) consisting of poly (vinyl alcohol) (PVA), ortho phosphoric acid (H3PO4), and Al2O3 nanoparticles (size ~50 nm) have been prepared by solution cast technique. Solid Polymer Electrolytes (SPE) (PVA-H3PO4: 70:30 wt%) as first phase host matrix and nanoparticles of Al2O3 as second phase dispersed in different wt. ratios are utilized for the preparation of thin films of NCPE. The DSC result shows that both glass transition and melting temperatures of SPE films decreases with addition of Al2O3 nanoparticles. The FTIR spectra give indication about possible interactions between host matrix and dopants for its complexation. It has been found that ionic conductivity (σ = 2.7 x 10-4 S/cm) of the NCPE film having 2 wt% of nanoparticles is enhanced by one order of magnitude over the conventional SPE system at room temperature. The ionic transport behaviors in both SPE and NCPE films have been characterized and compared in terms of ionic conductivity (σ) and ionic transference number (tion) responsible for ionic conduction. The temperature dependent conductivity behavior has been used to compute the activation energy (Ea) involved in the conduction process. © 2012 by Apple Academic Press, Inc.
Effect of plasticizer on ionic transport and dielectric properties of PVAH3PO4 proton conducting polymeric electrolytes
(2010) G.K. Prajapati; R. Roshan; P.N. Gupta
Solid polymer electrolytes have attracted considerable attention due to their wide variety of electrochemical device applications. The present paper is focused on the effect of plasticizer to study the structural, electrical and dielectric properties of PVAH3PO4 complex polymer electrolytes. XRD results show that the crystallinity decreases due to addition of plasticizer up to particular amount of polyethylene glycol (PEG) and thereafter it increases. Consequently, there is an enhancement in the amorphicity of the samples responsible for process of ion transport. This characteristic behavior can be verified by the analysis of the differential scanning calorimetry results. FTIR spectroscopy has been used to characterize the structure of polymer and confirms the complexation of plasticizer with host polymeric matrix. Electrical and dielectric properties have been studied for different wt% of plasticizer and their variations have been observed. The addition of PEG has significantly improved the ionic conductivity. The optimum ionic conductivity value of the plasticized polymer electrolyte film of 30 wt% PEG has been achieved to be of the order of 10-4 S cm-1 at room temperature and corresponding ionic transference number is 0.98. The minimum activation energy is found to be 0.25 eV for optimum conductivity condition. © 2010 Elsevier Ltd.