Department Of Physics

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Subject: search.filters.subject.Impedance spectroscopy

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    Investigation on enhancement of electrical, dielectric and ion transport properties of nanoclay-based blend polymer nanocomposites
    (Springer, 2019) Arya, A; Sharma, A.L.
    An intercalated blend polymer nanocomposite (PNC) films based on blend (PEO–PVC), LiPF6 as salt and modified montmorillonite (MMMT) as nanoclay are prepared via solution cast method. The impact of the nanoclay on the morphology, structure, polymer–polymer, polymer–ion interactions, ionic conductivity, voltage stability window, glass transition temperature, dielectric permittivity, and ac conductivity has been explored. The structural analysis evidenced the formation of blended and intercalated polymer nanocomposites. The FTIR analysis confirmed the interaction between polymer–ion-nanoclay, and polymer intercalation is evidenced by the out-of-the-plane mode [Si–O mode] of MMMT. An increase in the fraction of free anions with clay addition is confirmed. The highest ionic conductivity of about ~ 8.2 × 10−5 S cm−1 (at RT) and 1.01 × 10−3 S cm−1 (at 100 °C) is exhibited by 5 wt% MMMT based PNC. A strong correlation is observed between the glass transition temperature, crystallinity, melting temperature (Tm), ionic conductivity, relaxation time, and dielectric strength. The dielectric data have been fitted and enhanced dielectric strength and lowering of the relaxation time (τε′andτm) with clay addition evidences the faster segmental motion of polymer chain. The intercalated PNC shows thermal stability up to ~ 300 °C, high ion transference number (~ 1), and broad voltage stability window of ~ 5 V. An absolute agreement between ion mobility (μ), diffusion coefficient (D), and ionic conductivity is observed. An ion transport mechanism has been proposed on the basis of experimental results. Therefore, the proposed PNC can be adopted as electrolyte cum separator for energy storage devices. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Effect of variation of different nanofillers on structural, electrical, dielectric, and transport properties of blend polymer nanocomposites
    (Institute for Ionics, 2018) Arya,Anil; Sadiq, Mohd; Sharma, A.L.
    In the present work, the effect of various nanofillers with different particle sizes and dielectric constants (BaTiO3, CeO2, Er2O3, or TiO2) on blend solid polymer electrolyte comprising PEO and PVC complexed with bulky LiPF6 has been explored. The XRD analysis confirms the polymer nanocomposite formation. FTIR provides evidence of interaction among the functional groups of the polymer with the ions and the nanofiller in terms of shifting and change of the peak profile. The highest ionic conductivity is ~ 2.3 x10−55 S cm−1 with a wide electrochemical stability window of f ~ 3.5 V for 10 wt% Er2O3. The real and imaginary parts of dielectric permittivity follow the identical trend of the decreasing value of dielectric permittivity and dielectric loss with increase in the frequency. The particle size and the dielectric constant show an abnormal trend with different nanofillers. The AC conductivity follows the universal Jonscher power law, and an effective mechanism has been proposed to understand the nanofiller interaction with cation coordinated polymer.
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    Development of novel cathode materials based on MWCNT for energy storage/conversion devices
    (Springer Science and Business Media, LLC, 2017) Agnihotri, Shruti; Rattan, Sangeeta; Sharma, A. L.
    In Chap. 1, already available technology for energy storage solutions like capacitors, lead acid batteries, compressed air energy storage, flywheels has been discussed in order to compare their energy and power densities. Emphasis has been laid on Rechargeable Lithium ion Battery (Li-ion). Various materials which are already explored and used as cathode of battery has also been discussed with their merits and demerits. Further introduction of prepared orthosilicate material with used conductive additive Multiwalled carbon nano tube (MWCNT) has also given. In Chap. 2, methodology used to prepare respective Li2MnFeSiO4 material and its composite with MWCNT has been discussed in detail. Further, in order to validate its electrochemical application, different steps of cell assembly of Lithium half cell fabrication has also been discussed. Chapter 3 comprises of results obtained using standard Field emission scanning electron microscope (FESEM). Effect of used MWCNT on its morphology has been discussed in this chapter. A.C Impedance spectroscopy has been used to study variation in conductivity with respect to bared material. Possible reasons for increased conductivity with morphology has also been discussed in discussion. Chapter 4 includes conclusions drawn from mentioned results. This chapter summarizes measured conductivity values with different concentrations of MWCNT. Improved conductivity with respect to bared orthosilicate material has been pointed in this chapter. ? Springer International Publishing Switzerland 2017.