Department Of Physics

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Author: search.filters.author.Sharma, Achchhe LalSubject: search.filters.subject.Relaxation time

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    Impact of Shape (Nanofiller vs. Nanorod) of TiO2 nanoparticle on Free Standing Solid Polymeric Separator for Energy Storage/Conversion Devices
    (Wiley, 2018) Arya, Anil; Saykar, Nilesh G; Sharma, Achchhe Lal
    We report the investigation on examining the impact of nanofiller (NF)- versus nanorod (NR)-shaped titanium oxide(TiO2) nanoparticle on the structural, electrochemical, transport, thermal, and dielectric properties of the solid polymer electrolyte(SPE). Thin SPEfilms comprising of poly(ethylene oxide), sodium hexafluorophosphate, and dispersed with TiO2NF, TiO2NR (synthe-sized by hydrothermal route) has been prepared via solution cast technique. The shape of nanoparticle influences the morphologicaland structural properties as observed infield emission scanning electron microscope and X-ray diffraction analysis. The highest ionicconductivity was exhibited by the NR dispersed system and is higher than NF dispersed system for all recorded concentration consis-tently. It is attributed to the formation of the long-range conductive path with NR when compared with NF. In addition, the electro-chemical stability window is much higher (~5 V) than the NF-doped system. Furthermore, the dielectric properties of SPE wereinvestigated andfitted in the complete frequency window (1 Hz–1 MHz;T=40–100 C@10 C). It is observed that the NR dispersedsystem shows higher dielectric strength and low relaxation time with respect to NF dispersed system. The results suggest that the NRdispersed SPE possess enhanced properties and is more appropriate for an application in high energy density solid-state Na ion batte-ries.
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    Structural, Electrical and Ion Transport Properties of Free Standing Blended Solid Polymeric Thin Films
    (Springer, 2018) Arya, Anil; Sadiq, Mohd; Sharma, Achchhe Lal
    Blended solid polymeric thin films based on PEO–PVP complexed with LiBOB were synthesized by solution cast technique. The effect of salt on morphology, structure and electrochemical properties was examined. The XRD and FESEM analyses reveal the enhancement of amorphous content on salt addition. The FTIR spectroscopy evidences the complex formation and presence of various microscopic interactions. The ionic conductivity for the optimized system has been estimated and found to be two orders higher than the salt-free system, i.e., ~ 5.1 × 10−6 S cm−1 (@40 °C), and remains increasing with temperature i.e. 6.5 × 10−4 S cm−1 (@100 °C) for O/Li = 16. The enhancement of ionic conductivity is attributed to increase in the number density of mobile ions as concluded by the Rice and Roth model. The high tion (~ 0.99) evidences the ionic nature of complexed electrolyte. DSC analysis evidences the suppression of crystallinity and shift of glass transition and melting temperature toward lower temperature implies the enhancement of the amorphous content and forms the rubbery nature of the thin films which support the faster ion conductions. Finally, an interaction scheme is proposed for a better explanation of the ion transport on the basis of experimental findings.
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    Temperature and Salt-Dependent Dielectric Properties of Blend Solid Polymer Electrolyte Complexed with LiBOB
    (Springer, 2019) Arya, Anil; Sharma, Achchhe Lal
    In the present paper, the temperature and salt-dependent dielectric properties of poly(ethylene oxide) (PEO) and poly(vinyl pyrrolidone) (PVP) blend matrix complexed with LiBOB are investigated in the frequency range 1 Hz to 1 MHz and temperature range 40 °C to 100 °C (@10 °C). The real and imaginary part of the complex permittivity, complex conductivity have been simulated in the whole frequency window and the various fitted parameters were evaluated respectively. The estimated value of the dielectric constant and the ac conductivity increases with the increase of temperature. The lowering of relaxation time and hopping length is observed with the salt addition that is in correlation with the complex conductivity results. The modulus formalism was used to analyze the recorded dielectric data. The dc conductivity, hopping frequency, and segmental motion are strongly coupled with each other as evidenced by the Debye-Stoke-Einstein (DSE) plot. An interaction mechanism has also been proposed to explore the effect of temperature on the hopping length, relaxation time, hopping potential barrier and the segmental motion of the polymer chain.