Department Of Physics

Permanent URI for this communityhttps://kr.cup.edu.in/handle/32116/57

Browse

Author: search.filters.author.Alegaonkar, Prashant S.Has files: No

Search Results

Now showing 1 - 10 of 21
  • No Thumbnail Available
    Item
    Thermophysical Assessments on Self-Assembled Tellurium Nanostructures
    (American Chemical Society, 2023-09-01T00:00:00) Sudheer, Manjima; Rani, Pinki; Patole, Shashikant P.; Alegaonkar, Prashant S.
    Thermal properties of self-assembled nanostructures are of great importance to explain the structural phase transformation phenomenon. We report on the thermophysical assessments on tellurium nanostructures (TeN) that have been prepared using a facile wet-chemical technique by admixing precursor sodium telluride (Na2TeO3) and sodium molybdate (Na2MoO4) catalysts in hydrazine hydrate solution and heated at 120 �C, over 5-7 h. The extracted products (interval: 0.5 h) were subjected to a number of spectro-microscopic techniques including thermal measurements. Under identical growth conditions, the morphology of TeN was found to be transformed from Te nanotube (TT) to Te nanoflake (TF) at 6 h. Analysis revealed that Mo participated actively during 6 h of growth time, thereby making bonds with oxygen and the Te host lattice. At the vicinity of the phase transformation, Mo acquired an interstitial position in the hexagonal motif due to enhancement in catalytic efficiency that led to the formation of MoO2- moieties, which transiently reacted with host lattices resulting in surface charging of the tubes. This, in turn, created the coalescing effect with neighboring colloidal tubes through the van der Waals interaction. Thermal properties such as thermal conductivity, effusivity, diffusivity, and specific heat studied for TeN showed prominent surface effects. The increased surface area and enhanced amount of polycrystallinity resulted in unprecedently low thermal properties of TF due to severe phonon confinement. � 2023 American Chemical Society.
  • No Thumbnail Available
    Item
    Preparation and Energy Storage Assessment of Ti3C2 2d MXene and Its Possible Thinning Mechanism
    (Springer Nature, 2023-09-07T00:00:00) Singh, Diya; Rani, Pinki; Biswas, Sayani; Alegaonkar, Prashant S.
    Since after its discovery, MXene has captivated the focus of many researchers. In this work, we report on the low-temperature synthesis of Ti3AlC2 MAX phase at 800�? and its further etching to obtain Ti3C2 MXene. Initially, titanium (Ti), aluminium (Al), and graphite (C) precursors were taken in an appropriate volume proportion and add-mixed and grounded well via molten salt technique (Galvin et al. in J Eur Ceram Soc 38, 2018 [1]). The characterizations performed on powder such as FTIR, XRD, UV�Visible, SEM, and EDS confirmed Ti3AlC2 MAX phase. The MAX phase was subjected to the acid treatment (HF, concentration 40%) for ~ 80�h. The synthesized MXene was separated and investigated using FTIR, XRD, UV�Visible, SEM, and EDS techniques. The MXene was further employed to microwave treatment over the temperature 300�420�K at a discharge of power 120 W for 1�h. Analysis revealed that thickness of Ti3C2 layers is observed to be decreased with microwave treatment which can be a possible mechanism to obtain MXene quantum dots. In electrochemical analysis, specific capacitance for two electrode MXene@300�K and @400�K is reported to be 15 and 10�F/g, respectively, showing resistive nature of capacitance coupling for MXene. Analysis of electrochemical impedance spectroscopy together with bode showed the surface passivation effect of MXene layers to achieve different charge dynamics in both the systems. � 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
  • No Thumbnail Available
    Item
    Design and Manufacturing of a Hexapattern Frequency Selective Surface Absorber for Aerospace Stealth Application
    (American Chemical Society, 2023-07-21T00:00:00) Priyanka, None; Mohanty, Subrat; Alegaonkar, Prashant S.; Baskey, Himangshu B.
    Integrated frequency selective surface (IFSS) absorbers with larger bandwidth, effective reflection loss, polarization-insensitive characteristics, angular stability with compact/thin design, and ease of fabrication have captivated significant importance in stealth technology. Herein, we report on an IFSS absorber that has been designed, simulated, and implemented for manufacturing to achieve effective stealth properties. Initially, frequency selective surface (FSS) layers have been designed that comprise a closed centroid honeycomb structure surrounded with four annular hexagonal rings, splitted, alternatively, and enveloped with four L-shaped elements. The simulated pattern has been optimized on glass fabric for reflection loss (RC, dB) at a thickness of ?0.1 mm by choosing sheet resistance of pattern 110 ?/?. A FSS layer combined with interlayer lossy dielectric laminates (1.8 mm) and a carbon-fabric-reinforced-plastic ground has been simulated as an IFSS absorber. The performance of RC, in normal and angular configuration (0-60�), under transvers an electric/magnetic mode of polarization, including analysis of the displacement current, volume power loss distribution, and complex admittance has been carried on IFSS. Subsequently, the proposed absorber has been fabricated using customized carbon-based resistive ink imprinted on glass fabric by mask lithography compounded with laminates (a carbon black powder/epoxy composite) and ground. Their manufacturing details, including free space and anechoic chamber RC measurements, have been presented. The simulated and experimental RC performances of the absorber are found to be in good agreement, possessing minimal 10 dB reflection loss (90% absorption) with a sample thickness of 1.9 mm (0.05?L, where ?L corresponds to a lower operating frequency), covering 76% fractional bandwidth in X and Ku bands. The proposed design architecture of the IFSS is ideally suitable for aerospace stealth platforms. � 2023 American Chemical Society.
  • No Thumbnail Available
    Item
    Polarization-independent enhancement in UV photoconductivity of BiFeO3/Sn:In2O3 heterostructure
    (Elsevier B.V., 2023-05-08T00:00:00) Banda, Rajender Reddy; Halge, Devidas I.; Narwade, Vijaykiran N.; Kaawash, Nabeel M.S.; Thabit, Mohammed Y.H.; Alegaonkar, Prashant S.; Bogle, Kashinath A.
    Currently, polarization-dependent transport in ferroelectric materials under optical illumination is gaining a lot of attention in optoelectronics. This idea is implemented on BiFeO3 to illustrate its UV�Visible light photodetection property, however, naturally occurring bismuth or oxygen vacancies serve a major disadvantage as they interfere with its polarization ability. It is very difficult to overcome this defect issue in bismuth-based perovskites, therefore, based on this herein an enhancement in the photoconductive property of polycrystalline BiFeO3 thin film deposited via spray pyrolysis technique on Sn:In2O3 coated glass substrate is demonstrated without polarizing it. An extraordinary photodetection behavior with higher photoresponsivity (1.01 A/W) and external quantum efficiency (364) as well as faster response speed (6 ms) even under low UV illumination (340 nm) and lower applied bias of 2 V is observed. The roles of the BiFeO3�Sn:In2O3 interface, as well as the adsorption/desorption of oxygen molecules on the surface of BiFeO3 layers, were highlighted for the ferroelectric material's UV photodetector application. � 2023 Elsevier B.V.
  • No Thumbnail Available
    Item
    Electrical Conductivity of MXenes-Based Polymer Composites
    (CRC Press, 2023-04-07T00:00:00) Biswas, Sayani; Alegaonkar, Prashant S.
    MXenes are a new addition to the interesting class of 2D materials, and are a work in progress. There is a wide range of combinations and exciting properties associated with MXenes; one of them is their tendency to form polymer nanocomposites with enhanced features. Polymers and MXenes, when blended together, form a cohesive system in which the best properties of both the constituents are featured while the drawbacks are compensated. When MXenes are paired with conducting polymers, the resultant conductivity achieved surpasses the values produced individually. In this study, the electrically conductive nanocomposites of MXene and polymer are described, highlighting the most significant and recent works. These works are the stepping stones for future experiments of MXene-polymer composites to perfect their characteristics, conductivity and other electronic properties. � 2023 selection and editorial matter, Poushali Das, Andreas Rosenkranz, and Sayan Ganguly; individual chapters, the contributors.
  • No Thumbnail Available
    Item
    High-performance and ultra-sensitive ultraviolet photodetector based on surface passivated ?-Fe2O3 thin film
    (Elsevier Ltd, 2023-03-01T00:00:00) Kaawash, Nabeel M.S.; Halge, Devidas I.; Narwade, Vijaykiran N.; Alegaonkar, Prashant S.; Bogle, Kashinath A.
    Nanostructured ?-Fe2O3 is a versatile material and has attracted extensive attention due to its promising electrochemical and photoelectrochemical properties, which are widely investigated in water splitting, photoelectrochemical devices, gas sensors, and catalysis. Moreover, its band gap (Eg = 2.0 eV) allows it to absorb visible light, but due to poor charge carrier mobility, ultrafast recombination of the photo-generated carriers, and surface oxygen vacancy defects its application as a photodetector got restricted. Herein with a surface passivated ?-Fe2O3 film deposited on the glass substrate, the ultraviolet photodetector is demonstrated. The surface passivated photodetector is sensitive to ultraviolet light, showing a substantial enhancement in the photo-responsivity of 1.41 A/W, the external quantum efficiency of 515%, the photo-sensitivity of 1650%, and a reduction in response time of 0.06 ms (for 340 nm at a bias of +30 V) as compared with the device before surface passivation (0.228 A/W, 83%, 34%, and 1.6 ms), respectively. These improved properties are observed due to the suppression of surface defects via surface passivation, which increases free carrier concentration transport across the film. The surface passivated ?-Fe2O3 thin film-based photodetector with high photo-responsivity, photo-sensitivity, high speed, and ultraviolet photoresponse is promising for practical applications, and this platform opens up new avenues for the development of low-cost, and highly efficient ultraviolet photodetectors. � 2023 Elsevier B.V.
  • No Thumbnail Available
    Item
    Simple and Productive Method to Develop Highly Sensitive and Fast Infrared Photodetector Using Spray Deposited Nanocrystalline PbS Thin Film
    (Institute of Physics, 2023-02-16T00:00:00) Thabit, Mohammed Y. H.; Kaawash, Nabeel M. S.; Begum, Sumayya; Halge, Devidas I.; Narwade, Vijaykiran N.; Alegaonkar, Prashant S.; Bogle, Kashinath A.
    This work demonstrates the development of a highly sensitive and fast infrared photodetector using a PbS thin film deposited using a simple and scalable method known as "spray pyrolysis". An aqueous precursor solution was deposited on a glass substrate at 150 �C have a cubic phase of PbS. Silver electrodes with a 1 mm gap are drawn on the film to create photo-detector devices. Low resistive contact between the silver electrode and the PbS film is revealed from the linear I-V measurements performed in the dark and under light illumination. Under the illumination of a 100-watt tungsten lamp, the photo-responsivity, sensitivity, response time, and decay time of the PbS film were measured. The Ag/PbS/Ag photodetector device has a responsivity of 70 mA/W, a sensitivity of 200 at 30 V, and the best response and decay times of 6.4 and 15.6 ms, respectively. The photodetector device produced by this simple and low-cost fabrication method has a fast response and decay time. � Published under licence by IOP Publishing Ltd.
  • No Thumbnail Available
    Item
    Mitigation in broad band microwave shielding properties of Ni-Co/NC composite
    (Elsevier Ltd, 2023-02-09T00:00:00) Sahoo, Suprava; Tripathi, Krishna C.; Baskey, Himangshu; Alegaonkar, Prashant S.
    It is tactically important for a high-resolution seeking tracker to generate clutter, greatly facilitated by electromagnetic interference shielding. Nickel-Cobalt /Nano?carbon (Ni-Co/NC) composites are synthesized by a simple, solid-state combustion method. The scattering performance of Ni-Co/NC composites is reported over the frequency range of 2�18 GHz with varying equal weight % of Nickel and Cobalt from (5 to 25)% and characterized using X-ray diffraction, Fourier transform-infrared spectroscopy, Energy Dispersive X-ray spectroscopy, and Scanning Electron Microscope technique. Additionally, fabricated toroidal specimens are examined for reflection loss measurements. According to analysis, the phases NiO and NiCo2O4 are formed when nickel and cobalt are added to nano?carbon. These phases subsequently diffuse throughout the nano?carbon network to produce the Ni�O stretching vibration modes, O-X-O and X-O-X (where X = Ni or Co) modes. Asymmetric polarization at low nickel?cobalt weight % changes to symmetric polarization at higher weight % in the Ni-Co/NC composites. The analysis of constitutive parameters indicated a hybrid ac conductivity behaviour (Debye- and Jonscher-like), an increase in complex permittivity and permeability, and a variation in synergetic magneto-dielectric coupling energy with frequency. Additionally, the characteristic impedance and skin resistance have been calculated. In general, the 20-wt% Ni-Co/NC composite exhibits the highest absorption at 7.28 GHz at 3.85 mm of thickness at low frequency. However, over a higher frequency range, the 5-wt% Ni-Co/NC composite exhibits a high-performance shield design, achieving ?21.05 dB reflection loss at a thickness of 5.45 mm with 2.24 GHz of effective bandwidth. � 2023 Elsevier B.V.
  • No Thumbnail Available
    Item
    Reduced graphene oxide doped tellurium nanotubes for high performance supercapacitor
    (Frontiers Media S.A., 2022-10-20T00:00:00) Rani, Pinki; Alegaonkar, Ashwini P.; Biswas, Rathindranath; Jewariya, Yogesh; Kanta Haldar, Krishna; Alegaonkar, Prashant S.
    Supercapacitors have been achieving great interest in energy storage systems for the past couple of decades. Such devices with superior performance, mainly, depending on the material architecture of the electrodes. We report on the preparation of Tellurium nanotubes (Te-tubes diameter ?100�nm and length ?700�nm), with variable doping of conducting network reduced graphene oxide (rGO) to fabricate high-performance electrode characteristics of rGO @ Te. The prepared material was characterized using XRD, FTIR, FESEM, and Raman spectroscopy techniques, including Brunauer-Emmett-Teller, Barrett-Joyner-Halenda measurements. FTIR study revealed that 15% rGO @ Te has a wide C-O vibration band at ? 1,100�1,300�cm?1, over other compositions. FESEM study shows the Te-tubes dispersion in rGO layers. The EDX study revealed that 15% of the composition has an optimistic concentration of C and O elements. In other compositions, either at lower/higher rGO concentration, an uneven count of C and O is observed. These support efficient charge dynamics to achieve superior ultra-capacitor characteristics, thereby achieving specific capacitance Csp 170 + F/g @ 10�mV/s in a symmetric configuration. The reported values are thirty times higher than pristine Te-tubes (?5�F/g). This finding suggests that rGO @ Te is a promising candidate for supercapacitor. Copyright � 2022 Rani, Alegaonkar, Biswas, Jewariya, Kanta Haldar and Alegaonkar.
  • No Thumbnail Available
    Item
    Rationally designed state-of-the-art approach for enhancing the ultraviolet photon detection performance of ZnO thin film
    (Elsevier B.V., 2022-10-07T00:00:00) Kaawash, Nabeel M.S.; Halge, Devidas I.; Narwade, Vijaykiran N.; Alegaonkar, Prashant S.; Bogle, Kashinath A.
    Here, we demonstrate a simple and effective state-of-the-art (surface passivation) approach for enhancing the UV photo detection performance of ZnO thin films synthesized via spray pyrolysis. The surface passivated Ag/ZnO/Ag device (using polyvinyl alcohol layer) has low dark current of 1.1 nA as compared with the device without surface passivation (0.04 ?A). The significant decay in the dark current after surface passivation is due the reduction in the density of surface oxygen vacancies confirmed by PL measurements. The UV photon detection capability of the surface passivated ZnO thin film exhibits a significantly high photo response (3675), high photosensitivity (3.6 � 105), photo-responsivity (0.6 A/W) and fast response time (0.6 ms) under UV light (340 nm, 140 ?W/cm2). This straightforward approach superimposes surface defects, making the ZnO thin film more suitable for a wide range of electronic device applications while preserving the material's intrinsic properties. � 2022 Elsevier B.V.