BITS Faculty Publications
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Item Electrical transport in superionic thin films prepared by pulsed laser deposition(AIP, 2011) Dalvi, AnshumanSuperionic thin films are obtained using PLD technique from ion oxysalt glassy target. The structural and electrical properties of the films have been investigated. Partially amorphous nature of the films has been confirmed by X‐ray diffraction measurements. The electrical conductivity of the sample has been measured at well controlled heating rate of Conductivity temperature cycles suggest that deposited films are essentially ionic in nature.Item Li2SO4-Li2O-P2O5 Ionic glass dispersed with [Bmim] [PF6] ionic liquid: Electrical transport and thermal stability investigations(AIP, 2014-04) Dalvi, AnshumanA fast ionic composite is prepared by dispersion of Ionic liquid [Bmim][PF6] in glass matrix by mixing and through grinding. Amorphous/glassy nature of the samples is confirmed by X-Ray diffraction (XRD). Surprisingly, the electrical conductivity of the samples is found to be increasing by ∼ 2 orders of magnitude and exhibits typical Arrhenius behavior with low activation energy. DC polarization and impedance spectroscopy measurements suggest that samples are essentially ionic in nature. The conductivity isotherms were also obtained at different temperatures (T < 100 °C) and found to be appreciably stable at least for ∼ 10 days.Item Understanding of ionic transport in Ntp dispersed Na+ ion hybrid polymer nanocomposites using Xanes spectroscopy(International Atomic Energy Agency, 2018) Dalvi, AnshumanPresent investigation focuses on conductivity-structure correlation in NaTi2(PO4)2 (NTP) NASICON embedded novel hybrid polymer composites. Structural and electrical investigations suggest that for low NTP content salt ions prefer to move through polymer for electrical transport. However, for higher content, the surfaces as well as inner states of NTP crystallites facilitate the ionic conduction as suggested earlier alsoItem Electrical conductivity and thermal studies on [EMIM]BF4, Li+ and Cu2+ confined silica gel composites(AIP, 2020-11) Dalvi, Anshuman; Sivasubramanian, S.C.Ionic liquid ([EMIM]BF4), Li+ and Cu2+ confined silica gel of composition 33.3LiNO3-xCuCl2-1IL-(65.7- x)SiO2 have been prepared via sol gel route. Structural, thermal and electrical conductivity investigations have been carried out on these composites which reveal interesting results. X-ray diffraction patterns of the samples confirm their amorphous nature. TGA shows continuous water elimination from the as prepared composite. EPR spectrum shows existence of Cu2+ ions in the solid matrix at room temperature. Electrical conductivity of the composites increases with increase in the amount of CuCl2 in the composite as well as due to the increase in temperature. As these composites exhibit good ion conducting properties, they seem to have good potential as solid electrolytes in Li+ ion battery applications.Item Structural relaxation and electrical transport in NASICON reinforced Na+ ion solid polymer electrolytes(AIP, 2020-11) Dalvi, AnshumanNASICON (NaTi2(PO4)3 known as NTP) crystallites reinforcement in PEO-NaI polymer matrix leads to enhanced electrical transport. Thus, the effect of NTP ceramic filler particles on structural relaxation of polymer chains and conductivity relaxation has been studied using M′′-ω and σ′-ω spectra. Temperature dependence of dc conductivity exhibits Vogel-Fulcher-Tammann (VFT) nature for PEO-NaI and Arrhenius behavior for NTP-polymer composite films. The conductivity behavior of two samples (with and without NTP) near glass transition temperature of PEO reveals that NTP crystallites facilitate electrical transport by providing conduction pathways. Due to significant conductivity enhancement near room temperature, the composites are found to be potential candidates for all-solid-state Na+ ion battery applications.Item New generation Li+ NASICON glass-ceramics for solid state Li+ ion battery applications(AIP, 2018-04) Dalvi, AnshumanLithiumion conducting NASICON glass-ceramics have been prepared by a novel planetary ball milling assisted synthesis route. Structural, thermal and electrical investigations have been carried out on the novel composites composed of LiTi(PO4)3 (LTP) and 50[Li2SO4]-50[Li2O-P2O5] ionic glass reveal interesting results. Composites were prepared keeping the concentration of the ionic glass fixed at 20 wt%. X-ray diffraction and diffe rential thermal analysis confirm the glass-ceramic formation. Moreover, the structure of LTP remains intact during the glass -ceramic formation. Electrical conductivity of the glass-ceramic composite is found to be higher than that of the pristine glass (50LSLP) and LTP. The bulk and grain boundary conductivities of LTP exhibit improvement in composite. Owing to high ionic conductivity and thermal stability, novel glass -ceramic seems to be a promising candidate for all solid-state battery applications.Item Thermal stability and crystallization kinetics in superionic glasses using electrical conductivity–temperature cycles(AKJournals, 2010-12) Dalvi, AnshumanThe present work demonstrates application of electrical conductivity (σ)–temperature (T) cycles to investigate thermal properties viz., crystallization and glass transition kinetics in AgI–Ag2O–V2O5–MoO3 superionic glasses. The σ–T cycles are carefully performed at various heating rates, viz., 0.5, 1, 3, 5, and 7 K/min. The conductivity in Ag+ ion conducting glasses exhibit anomalous deviation from Arrhenius behavior near glass transition temperature (Tg) followed by a drastic fall at crystallization (Tc). The temperature corresponding to maximum rate of crystallization (Tp) is obtained from the derivative of σ–1/T plots. With increasing heating rates, the characteristic temperatures (Tg, Tp) are found to be shifting monotonically toward higher temperatures. Thus, activation energy of structural relaxation Es, crystallization Ec and other thermal stability parameters have been obtained from σ–T cycles using Kissinger equation and Moynihan formulation. For a comparative study, these kinetics parameters have also been calculated from differential scanning calorimetry plots. The parameters obtained from both the methods are found to be comparable within experimental error.