Faculty Publications
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Item A balancing between super transparency and conductivity of solution combustion derived titanium doped indium oxide: Effect of charge carrier density and mobility(Elsevier B.V., 2018) Pujar, P.; Vardhan, R.V.; Gupta, D.; Mandal, S.In this contribution, super transparent (~100%) and conducting In14Ti1O23 (Titanium doped Indium oxide; InTiO) films were reported via solution combustion processing with acetylacetone as fuel. Both bulk-powder and thin film systems were studied and revealed the efficacy of low temperature combustion synthesis which yielded crystalline InTiO powder at 150 °C and its film counterpart had shown pronounced crystalinity with temperature. Also, all films with varying annealing temperature were smooth with rms value ranging from 0.29 nm to 1.9 nm. In addition, the charge carrier density in all films found to be of the order 1019 cm?3, possessing highest transparency nearly equals to uncoated glass at an annealing temperature of 350 °C having maximum of ~67% metal-oxygen-metal framework (or lattice oxygen) confirmed via X-ray photoelectron spectroscopy. Also, the highest conductivity of 20 S/cm at an annealing temperature of 450 °C clearly conveyed the potential of solution combustion processing in the fabrication of ultra-transparent InTiO films with no sophistication in the film fabrication. © 2018Item A facile, low temperature spray pyrolysed tungsten oxide (WO3): an approach to antifouling coating by amalgamating scratch resistant and water repellent properties(Springer, 2020) Vardhan, R.V.; Kumar, S.; Mandal, S.In this study, a facile spray pyrolysed hydrophobic robust tungsten oxide (WO3) films were deposited at an annealing temperature of 400°C on inexpensive glass substrates, using clear and homogeneous precursor solution containing tungsten hexachloride and 2-methoxyethanol. The 10 and 15 times sprayed films were polycrystalline with the monoclinic crystal structure, uniform with the submicron-sized grain morphology (size ~320–420 nm), with an average surface roughness ranging from 12 to 17 nm and transparent above 60% in the visible region with a thickness of 380 and 550 nm, respectively. Elemental existence of tungsten and oxygen was recognized on the surface of the films possessing the highest lattice oxygen percentage of 91.1. Increment in the scratch hardness of the films with the number of sprays compared to uncoated glass was identified. The films were hydrophilic in nature (water contact angle <8°), converted to hydrophobic (>120°) by treating chemically with octadecyltrichlorosilane to form a self-assembled monolayer on the top and the hydrophobicity remained same (~120°) even after a year. These films with unique and combined properties of scratch hardness and hydrophobicity can serve in the potential application as antifouling coatings. © 2020, Indian Academy of Sciences.Item Ammonia gas detection by solution combustion-processed pristine & Ti-doped ZnO transparent films: a reverse effect of doping on gas response(Springer, 2023) Vardhan, R.V.; Manjunath, G.; Pothukanuri, P.; Mandal, S.In this contribution, pure, polycrystalline wurtzite crystal structured, spin-coated pristine ZnO and Ti-doped (1, 2, and 3 wt%) ZnO transparent films were accomplished at 400 °C through a facile solution combustion synthesis method. Crystallinity, roughness, and porosity in the pristine film were relatively higher than in the doped films. The demonstrated films were transparent, with ~ 70 to 90% in the visible region. The room temperature detection of ammonia (NH3) gas (25–100 ppm) was recognized in all the films. The pristine film revealed a superior gas response at every concentration of NH3 gas in contrast to all the doped films; it is probably due to comparatively high crystallinity, porosity, more oxygen vacancy concentration (1.788), and high fraction of adsorbed oxygen (20.55%). The film exhibited the highest gas response of 34.7 at 100 ppm of NH3 gas and a limit of detection of ~ 10.7 ppm with superior selectivity towards NH3 gas. Although doping enhanced the transparency but diminished the NH3 gas response due to the combined effect of deterioration in the mentioned properties achieved in pristine film. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Item Tracing of Ammonia Gas by Solution-Combustion-Derived Pristine and Nb-Doped TiO2 Films: Beneficial Impact of Crystallinity and Adsorbed Oxygen on the Gas Response(Springer, 2023) Vardhan, R.V.; Manjunath, G.; Pothukanuri, P.; Mandal, S.The current work delivers room-temperature ammonia (NH3) gas-detectable pristine, Nb-doped TiO2 air- and vacuum-annealed films obtained through the solution-combustion process. Polycrystalline anatase crystal structured films without any dopant oxide phases were processed at 400°C on glass substrates. The crystallinity was higher in pristine films than in doped films; the morphological features were similar in all the films. The films were > 50% transparent, and the estimated optical energy band gap was greater in doped films than in pristine films. All the films detected NH3 gas (25 ppm to 100 ppm) at room temperature, and the gas response was highly dependent on the crystallinity and relative area fraction of adsorbed oxygen (% of OA). The vacuum-annealed pristine film exhibited a better gas response than the other films at all NH3 gas concentrations due to high crystallinity and % of OA (10.15%). The film demonstrated maximum gas response of ~16 towards 100 ppm of NH3 gas and displayed good selectivity. Even though the doping reduced the crystallite size from ~17 nm to ~9 nm, it also diminished the crystallinity of the films, which significantly impacted the deterioration of their gas response. © 2023, The Minerals, Metals & Materials Society.Item Detection of ethanol gas at room temperature by In2O3-based screen-printed films fabricated through particle-free aqueous solution combustible inks(Institute of Physics, 2024) Vardhan, R.V.; Praveen, L.L.; Manjunath, G.; Pothukanuri, P.; Seikh, A.H.; Alnaser, I.A.; Mandal, S.The current work investigates the room temperature ethanol gas detection capabilities of pristine, Sn-doped, Zn-doped, Sn & Zn co-doped In2O3-based screen-printed films, fabricated using particle-free aqueous solution combustible inks on glass substrates. The fabricated films were pure, polycrystalline with cubic bixbyite crystal structure, porous, and transparent (∼75 to 95%) in the visible range. Relatively high surface roughness was detected in pristine film than in doped films. Ethanol gas was detected by all the films at room temperature. Among all, the pristine film showed a relatively greater gas response at all concentrations of ethanol gas ranging from 25 ppm to 100 ppm. This superior gas response was attributed to comparatively greater oxygen vacancy concentration (OV/OL), relative area fraction of surface adsorbed oxygen (% of OA), and high surface roughness with porosity. The maximum ethanol gas response attained was ∼17 at 100 ppm concentration by the pristine film, which also demonstrated high selectivity to ethanol gas. © 2024 The Author(s). Published by IOP Publishing Ltd.