Browsing by Author "Mandal, D."

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A study on the kinetics and structure of tungsten oxide nanopowder synthesized by an electrochemical oxidation process
(John Wiley and Sons Inc, 2025) Salot, M.; Santhy, K.; Mandal, D.; Pramanick, A.K.; Rajasekaran, B.; Avasthi, G.; Chaudhury, S.K.
Tungsten oxide possesses unique properties owing to its multiple oxidation states. They are produced by several techniques with each having their advantages and limitations. In this study, the hydrated tungsten oxide nanopowders with varied morphology were synthesized by electrochemical oxidation of WC-6Co scrap at room temperature. This process is efficient and requires low capital investment. The effect of processing parameters, namely voltage, molarity, temperature, and electrolyte stirring on yield, structure, morphology, and energy bandgap is studied. The X-ray diffraction (XRD) analysis showed that at low voltage and low molarity monoclinic WO3.2H2O nanoparticles are synthesized. In contrast, at high molarity and high voltage, orthorhombic WO3.H2O nanoparticles are synthesized. Further, the size of crystal decreases with the increase in voltage during electrochemical oxidation of WC-6Co pellet. The in-situ XRD analysis showed progressive transformation of as-synthesized nanopowder from orthorhombic to cubic crystal structure. Thermal treatments using microwave radiation and muffle furnace resulted in partial phase transformation of hydrated tungsten oxide to cubic WO3.H0.5 phase. The scanning electron microscopy and transmission electron microscopy analyses confirmed the formation of nanoplates, nanorods, and quantum dots depending on the processing parameters. The ultraviolet-visible spectroscopy showed a relatively lower energy bandgap of as-synthesized tungsten oxide nanopowder. © 2025 The American Ceramic Society.
Advanced Electrolyte Additives for Lithium-Ion Batteries: Classification, Function, and Future Directions
(American Chemical Society, 2025) Brijesh, K.; Jareer, M.; Lakshmi Sagar, G.; Mukesh, P.; Alagarsamy, A.; Mandal, D.; Nagaraja, H.S.; Shahgaldi, S.
Lithium-ion batteries (LIBs) are widely employed as energy storage devices, particularly in portable electronics and electric vehicles, owing to their high energy density and efficiency. Among the key components of LIBs, the electrolyte plays a crucial role in determining capacity, cycling stability, rate performance, the electrode/electrolyte interface, and overall battery efficiency. However, traditional electrolytes face significant challenges, including severe structural degradation and interfacial side reactions under high-voltage and high-temperature conditions. Protective layers, such as the cathode-electrolyte interphase (CEI) and solid-electrolyte interphase (SEI), are essential for addressing these issues. These layers inhibit electron transfer while allowing lithium-ion (Li+) transport, preserving the structural and electrochemical integrity of the battery. A cost-effective strategy to further enhance the electrode-electrolyte interface and boost LIB performance is the incorporation of carefully designed electrolyte additives. While some articles discuss the use of electrolyte additives in LIBs, there is a lack of detailed studies classifying these additives based on their chemical composition-based grouping. Such a classification enables a more focused examination of the roles and mechanisms by which these additives improve LIB performance. This review paper bridges this gap by examining various electrolyte additives and their contributions to enhancing the safety and performance of next-generation LIBs. It provides valuable insights into the current progress and challenges associated with additives in liquid electrolytes. The article is organized into seven sections, addressing boron-based electrolyte additives (Section 2), sulfur-based electrolyte additives (Section 3), phosphorus-based electrolyte additives (Section 4), fluorine-based electrolyte additives (Section 5), and nitrogen-based electrolyte additives (Section 6). Each section discusses specific examples, the formation of SEI and CEI layers, and the electrochemical properties of these additives. Furthermore, the article concludes with a summary and outlook, advocating for continued advancements in electrolyte engineering for LIBs. Â© 2025 American Chemical Society.
Advanced Electrolyte Additives for Lithium-Ion Batteries: Classification, Function, and Future Directions
(American Chemical Society, 2025) Brijesh, K.; Jareer, M.; Lakshmi Sagar, G.; Mukesh, P.; Alagarsamy, A.; Mandal, D.; Nagaraja, H.S.; Shahgaldi, S.
Lithium-ion batteries (LIBs) are widely employed as energy storage devices, particularly in portable electronics and electric vehicles, owing to their high energy density and efficiency. Among the key components of LIBs, the electrolyte plays a crucial role in determining capacity, cycling stability, rate performance, the electrode/electrolyte interface, and overall battery efficiency. However, traditional electrolytes face significant challenges, including severe structural degradation and interfacial side reactions under high-voltage and high-temperature conditions. Protective layers, such as the cathode-electrolyte interphase (CEI) and solid-electrolyte interphase (SEI), are essential for addressing these issues. These layers inhibit electron transfer while allowing lithium-ion (Li+) transport, preserving the structural and electrochemical integrity of the battery. A cost-effective strategy to further enhance the electrode-electrolyte interface and boost LIB performance is the incorporation of carefully designed electrolyte additives. While some articles discuss the use of electrolyte additives in LIBs, there is a lack of detailed studies classifying these additives based on their chemical composition-based grouping. Such a classification enables a more focused examination of the roles and mechanisms by which these additives improve LIB performance. This review paper bridges this gap by examining various electrolyte additives and their contributions to enhancing the safety and performance of next-generation LIBs. It provides valuable insights into the current progress and challenges associated with additives in liquid electrolytes. The article is organized into seven sections, addressing boron-based electrolyte additives (Section 2), sulfur-based electrolyte additives (Section 3), phosphorus-based electrolyte additives (Section 4), fluorine-based electrolyte additives (Section 5), and nitrogen-based electrolyte additives (Section 6). Each section discusses specific examples, the formation of SEI and CEI layers, and the electrochemical properties of these additives. Furthermore, the article concludes with a summary and outlook, advocating for continued advancements in electrolyte engineering for LIBs. © 2025 American Chemical Society.
Moment based delay modelling for on-chip RC global VLSI interconnect for unit ramp input
(2012) Halder, A.; Maheshwari, V.; Goyal, A.; Kar, R.; Mandal, D.; Bhattacharjee, A.K.
The Elmore delay has been the metric of choice for the performance driven design applications. But the accuracy of the Elmore delay is insufficient. This paper presents an accurate and efficient model to compute the delay metric of on-chip high speed VLSI interconnects for ramp inputs. The proposed delay metric is based on the distributed RC interconnect model. For optimization like physical synthesis and static timing analysis, efficient interconnect delay computation is critical. In this paper, a delay metric using RC-out has been formulated which computes the delay at the output node. The proposed model is based on the first three moments of the impulse response. Two pole RC model is developed based on the first, second and third moments' effect onto the delay calculation for interconnect lines. This two pole approach permits the pre-characterization of the interconnect delay. The empirical D3M metric is shown to be a typical case. The proposed metric also provides an expression for impulse response. The SPICE simulation results justify the accuracy and efficacy of the proposed model. � 2012 IEEE.
Moment based delay modelling for on-chip RC global VLSI interconnect for unit ramp input
(2012) Halder, A.; Maheshwari, V.; Goyal, A.; Kar, R.; Mandal, D.; Bhattacharjee, A.K.
The Elmore delay has been the metric of choice for the performance driven design applications. But the accuracy of the Elmore delay is insufficient. This paper presents an accurate and efficient model to compute the delay metric of on-chip high speed VLSI interconnects for ramp inputs. The proposed delay metric is based on the distributed RC interconnect model. For optimization like physical synthesis and static timing analysis, efficient interconnect delay computation is critical. In this paper, a delay metric using RC-out has been formulated which computes the delay at the output node. The proposed model is based on the first three moments of the impulse response. Two pole RC model is developed based on the first, second and third moments' effect onto the delay calculation for interconnect lines. This two pole approach permits the pre-characterization of the interconnect delay. The empirical D3M metric is shown to be a typical case. The proposed metric also provides an expression for impulse response. The SPICE simulation results justify the accuracy and efficacy of the proposed model. Â© 2012 IEEE.
Soil Moisture Retrieval Over Crop Fields from Multi-polarization SAR Data
(Springer, 2023) Shilpa, K.; Suresh Raju, C.; Mandal, D.; Rao, Y.S.; Shetty, A.
Soil moisture estimation from agriculture fields using SAR measurements is a challenging process owing to the presence of vegetation canopy. In this study, the soil moisture (SM) is retrieved from multi-polarization airborne L- and C-band E-SAR data of different agriculture fields by using the radar parameter, Radar Vegetation Index (RVI). The retrieval methodology employs the semi-empirical Water Cloud Model (WCM) for vegetation-soil system modeling, followed by an inversion algorithm based on a Look Up Table approach. The impact of using different vegetation descriptors, both from in situ measured (Leaf Area Index, Wet Biomass and Vegetation Water Content) and radar derived (L-band RVI and C-band RVI), on the WCM inversion for SM retrieval is examined. The use of the RVI as the vegetation descriptor, which is obtained from C-band data, improves soil moisture retrieval with an RMSE of 7–8% volumetric soil moisture at L-band. © 2023, Indian Society of Remote Sensing.
Tungsten and fluorine co-doping induced morphology change and textured growth of spray-pyrolyzed SnO2 thin films viable for photocatalytic application
(Elsevier B.V., 2023) Maharana, G.; Reddivari, R.; Yuvashree, J.; Mandal, D.; Mondal, S.; Kovendhan, M.; Fernandes, J.M.; Laxminarayana, G.; Joseph, D.P.
Physicochemical aspects of numerous metal oxide based thin films are crucial for various optoelectronic applications. Cationic (W) and anionic (F) co-doping strategy into SnO2 thin film has been adapted in order to tune the optoelectronic parameters. X-ray diffraction pattern reveals successful doping of ‘W’ and ‘F’ into the SnO2 lattice and textured growth along (111) plane direction at the expense of suppression of the (211) plane. X-ray photoelectron spectroscopy confirmed the charge states of Sn4+, W6+, O2− and F1− elements present in the films. Scanning electron microscopy shows that tetragonal morphology of pure and F-doped SnO2 changes to a network-like feature upon ‘W’ co-doping and the elemental composition is also ensured. The contact angle measurement gives the surface wettability nature, which indicates all the films are hydrophilic. The 10 wt.% F-doped SnO2 shows a maximum transmittance of 89.36 % at 550 nm with a direct band gap of 3.82 eV. Electrical transport parameters are measured using linear four-probe and Hall effect techniques. Photocatalytic activity of methylene blue dye degradation showing a maximum efficiency for pure and solely F-doped SnO2 thin films are explained based on the obtained optoelectronic parameters. © 2023 Elsevier B.V.