Department Of Physics

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Author: search.filters.author.Sharma, A.L.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.