Department of Physics
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Item Electrical conductivity and Hall conductivity of a hot and dense hadron gas in a magnetic field: a relaxation time approach(APS, 2019-05) Das, ArpanWe estimate the electrical conductivity and the Hall conductivity of a hot and dense hadron gas using the relaxation time approximation for the solution of the Boltzmann transport equation in the presence of an electromagnetic field. We investigate the temperature and the baryon chemical potential dependence of these transport coefficients in the presence of a magnetic field. The explicit calculation is performed within the ambit of the hadron resonance gas model. In general, it is observed that the electrical conductivity decreases in the presence of a magnetic field. While at vanishing magnetic field the electrical conductivity decreases monotonically with temperature, in the presence of a magnetic field the same shows a nonmonotonic behavior with a peak. The Hall conductivity, on the other hand, shows a nonmonotonic behavior with respect to the dependence on a magnetic field as well as with temperature. We argue that for a pair plasma (particle-antiparticle plasma) where 𝜇𝐵 =0 , Hall conductivity vanishes. Only for a nonvanishing baryon chemical potential, Hall conductivity has a nonzero value. We also estimate the electrical conductivity and the Hall conductivity as a function of the center of mass energy along the freeze-out curve as may be relevant for relativistic heavy-ion collision experiments.Item Electrical conductivity and Hall conductivity of a hot and dense quark gluon plasma in a magnetic field: a quasiparticle approach(APS, 2020-02) Das, ArpanWe estimate here the electrical and Hall conductivity using a quasiparticle approach for quark matter. We use a Boltzmann kinetic approach in the presence of external magnetic field. We confront the results of model calculations with lattice QCD simulations for vanishing magnetic field. In general, electrical conductivity decreases with magnetic field. The Hall conductivity on the other hand can show a nonmonotonic behavior with magnetic field due to an intricate interplay of behavior of relaxation time and strength of the magnetic field. We argue for vanishing quark chemical potential Hall conductivity vanishes and quark gluon plasma with finite quark chemical potential can show Hall effect. Both electrical conductivity and Hall conductivity increase with increasing quark chemical potential.Item META Ion trapping in nematic liquid crystal by incorporating functionalised silver nanoparticles. P. 4(INIS, 2019-07) Manjuladevi, V.; Gupta, Raj KumarIn this work, the effect of functionalised silver nanoparticles (f-AgNPs) on the dielectric constant, electrical conductivity and birefringence of a rod shaped NLC 4-trans-pentyl cyclohexylcyanobenzene (5PCH) has been investigated in the planar cell as a function of temperature. The magnitude of dielectric anisotropy, elastic constants and birefringence in nanocomposites of 5PCH were enhanced with increasing concentration of f-AgNPs indicating enhancement of order parameter in the nematic medium. From the study it is observed that, the conductivity has reduced in f-AgNps nanocomposites of 5PCH compared to pure 5PCH due to the absorption of ions by f-AgNPs which is further confirmed by measuring transient current and ion transport number. So our results show that f-AgNPs can be used as ion trapping agent with other improved physical properties suitable for display devicesItem Investigation on physical properties of silver nanorod doped nematic liquid crystal(AIP, 2021-09) Manjuladevi, V.; Gupta, Raj KumarImprovement in the physical properties of nematic liquid crystals plays an important role in the performance of display devices. In the present study, the physical properties of silver nanorod (AgNR) doped nematic liquid crystal is investigated. The negligible change is observed in the value of birefringence for the lower doping concentration of AgNR in NLC. The parallel and perpendicular components of dielectric permittivity at T-TIN = −15 ° C increase with the addition of lower concentration (≤ 0.5 wt%) of silver nanorods to the NLC host. The ac conductivity decreases with the increase in the dopant concentration because of the trapping of ionic impurities of NLCItem 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 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.