Faculty Publications
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Item Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer(American Institute of Physics Inc. subs@aip.org, 2018) Kumari, K.; Ram, S.; Kotnala, R.K.In this investigation, we explore a facile synthesis of Fe3BO6 in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe2O3-B2O3 precursor. This study includes high resolution transmission electron microscopy (HRTEM) images, magnetic, optical, and impedance properties of the sample. HRTEM images reveal small tubes of Fe3BO6 of 20 nm diameter. A well resolved hysteresis loop appears at 5 K in which the magnetization does not saturate even up to as high field as 50 kOe. It means that the Fe3BO6 nanotubes behave as highly antiferromagnetic in nature in which the surface spins do not align along the field so easily. The temperature dependent impedance describes an ionic Fe3BO6 conductor with a reasonably small activation energy Ea ? 0.33 eV. Impedance formalism in terms of a Cole-Cole plot shows a deviation from an ideal Debye-like behavior. We have also reported that electronic absorption spectra are over a spectral range 200-800 nm of wavelengths in order to find out how a bonded surface layer present on the Fe3BO6 crystallites tunes the 3d ? 3d electronic transitions in Fe3+ ions. © 2018 Author(s).Item Structural, vibrational and surface analysis of Fe3BO6 nanoplates synthesized by combustion method(Elsevier B.V., 2018) Kumari, K.In the present investigation, a simple synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide (Fe2O3) and boric acid (H3BO3) using camphor (C10H16O) as fuel in microwave oven in order to form a single phase Fe3BO6 crystallites. An as-prepared ceramic powder in this way after combustion of a precursor, which contained a lot of residual carbon left after the combustion, was reheated at 400 °C to burn it out as oxide in a reaction with air. This is a very simple and fast method to form a phase pure compound from usual metal salts with functional properties. The size and morphology of the Fe3BO6 crystallites has been characterized in terms of X-ray diffraction (XRD) pattern in correlation to the field emission scanning electron microscopy (FESEM) image. A single phase compound Fe3BO6 of an orthorhombic crystal structure with Pnma space group and average crystallites size D = 46 nm is analyzed from the XRD pattern. IR/Raman and X-ray photoelectron spectroscopy (XPS) spectra studied for the Fe3BO6 samples in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. The XPS bands in Fe3+, B3+ and O2? species and IR/Raman bands in the oxygen polygons confer the results of forming Fe3BO6 with a bonded surface layer. © 2018 Elsevier B.V.Item Thermal stability and spectroscopic properties of Fe 3 BO 6 of small crystallites with a bonded carbon surface layer(Elsevier Ltd, 2019) Kumari, K.A well-known canted antiferromagnetic Fe 3 BO 6 with functionalized properties is an important material useful for light energy carrier, electrodes, gas sensors, and biological probes. In this investigation, a facile synthesis is explored in order to obtain Fe 3 BO 6 of small crystallites in a specific shape of nanoplates by self-combustion method. To access (i) whether Fe 3 BO 6 is formed at the as-prepared stage and (ii) how it stands stable with a residual carbon surface layer, thermal gravimetric (TG) analysis has been carried out by heating 10–20 mg powder (as-prepared) at a typical 10 K/min heating rate over 300–1100 K under air or argon atmosphere. The electronic absorption, infrared (IR) and Raman spectra studied for the Fe 3 BO 6 sample in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. IR and Raman bands in the oxygen polygons also confer the results of forming Fe 3 BO 6 with a bonded surface carbon layer. A stable bonded surface layer supports thermal stability of small crystallites and it affects other useful functional properties. © 2018 Elsevier B.V.Item Room-temperature detection of ammonia and formaldehyde gases by La xBa1?xSnO3?? (x = 0 and 0.05) screen printed sensors: effect of ceria and ruthenate sensitization(Springer Science and Business Media Deutschland GmbH, 2021) Manjunath, G.; Vardhan, R.V.; Praveen, L.L.; Pothukanuri, P.; Mandal, S.In the present work, gas sensing properties of the screen printed ceria and ruthenate-sensitized BaSnO3 (BSO) with La doping heterostructure sensors towards the detection of ammonia and formaldehyde gases at room temperature were studied. Adhered, porous screen printed films with different morphologies were obtained by depositing the LaxBa1?xSnO3?? (x = 0 and 0.05) powder particles prepared by the polymerized complex method. Ceria and ruthenate sensitization for screen printed LaxBa1?xSnO3?? (x = 0.05) film was processed through dip-coating in the 0.03 M aqueous solution of CeCl3 and RuCl3, respectively. La-doped BaSnO3 (LBSO) sensor with smaller crystallites, needle-like morphology and high concentration of oxygen vacancies exhibited superior gas response of 65 and 29 towards 50 ppm of ammonia and formaldehyde gases, respectively. Superabundant sensitization of ceria and ruthenate reduced the oxygen vacancy and structural open porosity in the LBSO sensor; therefore, the ammonia gas response was decreased from 65 to 14 and 3, respectively, whereas the formaldehyde gas response was reduced to less than 1/6th times the LBSO sensor. Limit of detection of LBSO sensors was estimated to be ~ 1 and ~ 2 ppm against ammonia and formaldehyde, respectively. The presence of fluorite structured phase ceria with high oxygen atoms storage capacity facilitates the rapid oxidization of analyte gases and caused the expeditious response (75 s) and recovery (60 s) in CeOx-sensitized LBSO sensor. This study might give a new insight into the development of doped and sensitized BSO-based gas sensors operating at ambient conditions. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.Item Ultra-sensitive clogging free combustible molecular precursor-based screen-printed ZnO sensors: a detection of ammonia and formaldehyde breath markers(Springer, 2021) Manjunath, G.; Pothukanuri, P.; Mandal, S.It is beneficial to develop the cost-effective, ultra-sensitive ZnO-based sensor for the rapid detection and quantification of the ammonia and formaldehyde breath markers under ambient conditions. Here, one-step solution route was adopted to formulate the aqueous combustible molecular precursor-based clogging free screen-printing ink consisting of zinc nitrate as an oxidizer, glycine as fuel, and eco-friendly binder sodium carboxymethylcellulose. The formulated precursor was deposited on the glass substrates via a screen-printing technique followed by annealing at different temperatures for an hour. Screen printed ZnO sensors processed at 500 °C with high crystallinity, less lattice distortion, low optical bandgap, and high concentration of donor defects showed remarkably high NH3 gas response ~ 336 and a moderate HCHO response ~ 16.4 towards the 5 ppm and 10 ppm of the respective gases. In addition it's LOD values is drawn as 0.6 ppm and 2.9 ppm for NH3 and HCHO gases, respectively, and exhibits superior selectivity towards ammonia. Faster diffusion of oxygen vacancies (Vo) in the smaller crystallites resulted expeditious sensor kinetics in the screen-printed sensor processed at 400 °C. Response and recovery time were recorded to be 50 s and 50 s to the 5 ppm of NH3, respectively. The crystallinity-dominant domain overcomes the adverse effect of larger grains on the gas response of screen-printed ZnO sensor processed at 500 °C. Robust, scalable, and cost-effective screen-printed ZnO conductometric sensors demonstrated here has a potential application in clinical diagnosis, and also in monitoring the NH3 and HCHO gases at low ppm-level. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.Item Investigations on thermo-mechanical properties of organically modified polymer clay nanocomposites for packaging application(SAGE Publications Ltd, 2021) Sudhakar, Y.N.; Muthu, M.; Bhat, D.K.Eco-friendly packing polymer materials are in the spotlight but, lack of new biodegradable polymers either natural or synthetic is yet to establish the market more competitively. So, in the present work, clay as a nano-filler is embedded and organically modified in some synthetic and natural polymers which are well established commercially to enhance their biodegradability. The impact of clay on the properties of synthetic polymers namely, poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and natural polymer cellulose acetate butyrate (CAB) was studied. Results from differential scanning calorimetric (DSC) showed a decrease in the glass transition temperature of organically modified polymer clay nanocomposites (PCC) than pure polymers. Scanning electron microscopy (SEM) displayed a uniform surface with small-sized crystallites distributed on the polymer surface. X-ray diffraction (XRD) spectra revealed the formation of enhanced intercalated structures in PCC. Furthermore, FTIR studies showed that the interlayer bonding (Si–O bands) of pure clay is deformed in PCCs. The tensile strength of PCC increased with an increase in organo-clay loading. This unique mechanical behavior is due to the agglomeration of organo-clay particles. Finally, the biodegradation studies revealed enhanced hydrolytic degradation in PCC than pure polymers. Hence, these PCCs are environmentally friendlier than their pure synthetic polymers without significant compromise in their properties, which makes it suitable for packaging industries. © The Author(s) 2020.Item Reduced graphene oxide/polyaniline/vanadium pentoxide/stannic oxide quaternary nanocomposite, its high energy supercapacitance and green electrolyte(Springer, 2024) Viswanathan, A.; Nityananda Shetty, A.N.Challenge of achieving high energy density (E) comparable with Li-ion batteries in supercapacitors, with low potential window offering aqueous electrolytes (1.2 V) has been overcome by using the electrode material composed of rGO 3.70%:PANI 51.86%:V2O5 33.33%:SnO2 11.11% (GPVS). The GPVS exhibited different extents of energy storage in the presence of 1 M sulphuric acid (H2SO4) and acidified supernatant liquid (ASL), a green electrolyte. Here, the ASL is the by-product, which is obtained as supernatant liquid after the synthesis of GPVS composites in an in situ synthetic method, and acidified using conc. H2SO4. The energy storage obtained in the presence of ASL is 38% higher than the energy storage obtained in the presence of H2SO4. The GPVS exhibited a remarkable feature of amelioration of energy storage with increase in CV cycles in the presence of H2SO4. The GPVS exhibited an extraordinary cyclic stability up to 41,300 cycles. The energy storage parameters achieved in the presence of H2SO4 after 33,800 cycles are, a specific capacitance (Cs) of 694.44 F g?1, an E of 138.88 W h kg?1 (comparable with E of Li-ion batteries) and a power density (P) of 2.1020 kW kg?1 at 1 A g?1. The energy storage parameters achieved in the presence of ASL are, a Cs of 212.31 F g?1, an E of 42.46 W h kg?1 (comparable with E of Ni–Cd batteries) and a P of 3.1583 kW kg?1 at 2 A g?1. It is satisfying that all these high energy characters are achieved with the real two electrodes–supercapacitor cell step up. The green supercapacitors are made by using the by-product, which is obtained as supernatant liquid after the synthesis of GPVS as its electrolytes. © Indian Academy of Sciences 2024.Item Dual storage mechanism of Bi2O3/Co3O4/MWCNT composite as an anode for lithium-ion battery and lithium-ion capacitor(Elsevier B.V., 2024) Lakshmi Sagar, G.; Brijesh, K.; Mukesh, P.; Hegde, A.P.; Kumar, A.; Kumar, A.; Bhat, K.S.; Nagaraja, H.S.Bismuth oxide(Bi2O3) and cobalt oxide(Co3O4) are promising owing to their unique properties, high storage capacity, low cost, and eco-friendliness, making them ideal for lithium-ion batteries(LIBs) and lithium-ion capacitors(LICs) anodes. This study presents the synthesis and thorough characterization of Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT composites as potential LIB and LIC anode materials. The materials are synthesized using a hydrothermal process succeeded by annealing. Structural, morphological, and compositional studies were analyzed. Various tests evaluated electrochemical performance, including cyclic voltammetry(CV), confirming a dual storage mechanism like alloying and conversion reaction involved for better energy storage. Specific discharge capacities of 834 mAh/g and 1184 mAh/g were recorded for Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT composite electrodes at a current density of 100 mA/g, respectively. The composite material exhibited notably enhanced rate capability, with 31 % and 51 % discharge capacities for Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT, respectively. The cyclic stability assessment revealed that Bi2O3/Co3O4 and Bi2O3/Co3O4/MWCNT maintained a high coulombic efficiency of around 99 % over 250 charge–discharge cycles at a high current density of 1 A/g. The capacity retention was approximately 253 mAh/g for Bi2O3/Co3O4 and 439 mAh/g for the Bi2O3/Co3O4/MWCNT composite, indicating excellent cyclic stability and minimal energy loss during cycling. Moreover, the LICs assembly of Bi2O3/Co3O4/MWCNT//CB was investigated, revealing a power density of 200 W kg?1 alongside an energy density of 8.64 Wh kg?1. The cyclic stability assessment over 10,000 cycles exhibits a capacity retention of approximately 45 % under a high current density of 2 A/g. © 2024 Elsevier B.V.Item Insights into the potential of Sb alloyed Cu2AgBiI6-based solar cells: For efficient indoor energy-harvesting(Elsevier Ltd, 2025) Kumar, A.; Siddharth, G.; Dwivedi, P.; Pandey, S.K.; Sengar, B.S.; Garg, V.Recently, indoor photovoltaics have attracted significant attention due to their remarkable capability to generate power from indoor light sources. This work investigates the performance of perovskite-inspired material Sb alloyed Cu2AgBiI6 (CABI-Sb) based indoor photovoltaic device, which has shown a power conversion efficiency of 9.53 %, reported in a recent experimental study by B. Al-Anesi et al. The baseline model of the CABI-Sb device structure (FTO/TiO2/CABI-Sb/Spiro-OMeTAD/Au) is developed in SCAPS-1D using the earlier reported experimental data. Baseline model parameters under WLED illumination are Jsc: 128.2 µA/cm2, Voc: 0.51 V, FF: 66.57 %, and PCE: 9.53 %, with a minor deviation of less than 1 %, which validates the developed model with experimental data. The performance of the device is fine-tuned by optimizing 1) Absorber thickness and defect density 2) Electron Transport Layer (ETL) doping density, conduction band offset (CBO) and interface defect density between the ETL/absorber (TiO2 /CABI-Sb) interface, 3) Hole Transport Layer (HTL) doping density, valence band offset (VBO) and interface defect density between HTL/absorber (CABI-Sb/Spiro-OMeTAD) interface, 4) work function of contacts, and 5) Series and shunt resistance were optimized. The performance parameters of the optimized device under the WLED illumination are Jsc: 1.84 mA/cm2, Voc: 1.60 V, FF: 86.78 %, and PCE: 49.31 %. A remarkable improvement in PCE is achieved from 9.53 % to 49.31 %. Further, to validate the suitability of the optimized device under different indoor environments, optimized device performance is evaluated under different lux intensities of WLED (6500 K), WLED (2700 K), compact fluorescent light (CFL), and halogen. © 2024 International Solar Energy SocietyItem Efficient removal of hazardous dyes/heavy-metal ions by in-house fabricated poly (vinylidene fluoride) thin-film nanocomposite membranes with functionalized Zr-based metal-organic framework(Elsevier Ltd, 2025) Prabhakar, N.; Isloor, A.M.; Farnood, R.; A.F., A.F.The need for effective solutions to address removal of dyes and heavy metal ions from water has driven significant interest in membrane science and separation technology. This work explores the potential of EDTA-modified MOF-808 as a novel additive to enhance the performance of PVDF supported TFC membranes. The innovation lies in aiming the unique properties of MOF and the chelating properties of EDTA in rejecting the target pollutants. The thin film nanocomposite membranes fabricated in this study with optimized MOF-EDTA loading demonstrated remarkable improvement in hydrophilicity, surface smoothness, porosity, and morphology as confirmed by water contact angle, atomic force microcopy, water uptake, and scanning electron microscopy. The optimized membrane with 0.1wt% MOF-808-EDTA exhibited a water flux of 37.36 Lm-2h-1, a 2.7-fold increment compared to the unmodified one. This was complemented by 98.6%, 91.48%, 88.7%, and 88.96% rejections in hazardous heavy metal ions namely lead, arsenite, cadmium and mercury respectively along with more than 95% rejections for 50ppm of sunset yellow and reactive black 5 dyes. The study also highlights the significant enhancement in antifouling properties with a reduction in irreversible fouling from 41.5% to 5.68% along with a flux rejection ratio of 94.3%. These findings underscore the potential of EDTA-modified MOF as an additive in enhancing the performance and durability of TFC membranes paving the way for efficient and sustainable water treatment. The current study explores an innovative approach for mitigating heavy metal ion and dye pollution in water via fabrication of. © 2025 Published by Elsevier Ltd.