Faculty Publications
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Item Development of low temperature stoichiometric solution combustion derived transparent conductive ternary zinc tin co-doped indium oxide electrodes(Royal Society of Chemistry, 2017) Pujar, P.; Gandla, S.; Singh, M.; Gupta, B.; Tarafder, K.; Gupta, D.; Noh, Y.-Y.; Mandal, S.Here, the development of transparent conductive zinc tin co-doped indium oxide (IZTO: In1.4Sn0.3Zn0.3O3) ternary electrodes is addressed through low temperature solution combustion processing. Optimization of fuel to oxidizer ratio offers low temperature (?130 °C) of combustion with balanced redox reaction. The thin films of IZTO annealed at different temperatures showed a decreasing trend in the resistivity with a fixed order of 10-2 ? cm and the film with a highest Hall mobility of 5.92 cm2 V-1 s-1 resulted at 400 °C. All the films with different temperatures of annealing were smooth (rms ? 2.42 nm) in nature and the IZTO film annealed at 200 °C is 83% transparent in the visible spectra. The effective band gap of 0.9 eV determined from first-principles density functional theory gives clear evidence for the conducting nature of IZTO. The thin film transistor fabricated with IZTO as a gate electrode with poly(methyl methacrylate) and pentacene as the dielectric and channel material, respectively, exhibited a saturation mobility of 0.44 cm2 V-1 s-1 and Ion/Ioff ratio of 103. Further, the printability of the IZTO combustible precursor is established which resulted in anti-edge deposition of the printed feature. © 2017 The Royal Society of Chemistry.Item Facile in situ formation of high conductive Ag and Cu x O y composite films: a role of aqueous spray combustion(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Salian, A.; Pujar, P.; Mandal, S.In the present contribution, in situ formation of low-temperature high conductive composite films composed of pure silver and oxides of copper (Cu x O y where, x = y = 1 for CuO and x = 2, y = 1 for Cu 2 O), are presented through spray combustion with a balanced stoichiometric redox reaction. High electrical conductivity (~ 7.8 × 10 5 S/cm) was retained in the composite film at an annealing temperature of 170 °C with matrix silver phase being 50% by volume. Whereas electrical conductivity of spray combustion processed pure silver is found to be ~ 2 × 10 6 S/cm. In situ formation of the composite film directly from the silver and cupric nitrate aqueous precursor solution through spray combustion proves it to be compositionally tunable with minimal usage of noble metal. Presence of Ag and Cu x O y is confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The ratio of Cu 1+ /Cu 2+ in the composite is found to be 0.54 and 0.43 at an annealing temperature of 170 °C and 400 °C respectively. The transformation of Cu 2 O to CuO is highly a thermally activated phenomenon; as the vacancy driven electrical conductivity is more in Cu 2 O than CuO, stabilization of Cu 2 O at a lower temperature is desired. The composite electrode can have potential applications in optoelectronics, printed electronics and catalysis. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.Item High-performance low voltage operation of indium zinc tin oxide thin film transistors using chemically derived sodium ?-alumina dielectric(Springer, 2019) Pujar, P.; Gupta, D.; Mandal, S.We present high performance, low voltage (< 3 V) operation of thin film transistors (TFTs) with indium zinc tin oxide (IZTO: In4Sn4ZnO15)-semiconductor. The film of IZTO was fabricated via low-temperature (200 °C) solution combustion processing without incorporating an external fuel. As 2-methoxyethanol is a widely used organic solvent due to its high dissolution capability, serve the purpose of both the solvent and the fuel. On quantification from the balanced redox reaction, 0.3% of 2-methoxyethanol assisted for the action of fuel and helped in the formation of metal oxide, and the rest (99.7%) served the purpose of being dissolution medium. The balanced redox chemistry yielded a significant fraction of (56.5%) metal oxide at 200 °C confirmed via high-resolution oxygen 1 y spectrum. Further, the chemically derived thin film of sodium ss-alumina with a dielectric constant of ~ 21, while annealing at 350 °C incorporated in the TFT for the realization of low voltage operation. The performance assessment is systematically carried out both silicon dioxide (SiO2) and sodium ss-alumina and found that the TFTs with SiO2 and IZTO exhibited a saturation mobility (µ^), Ion/Ioff ratio and the threshold voltage (Vth) of 0.50 ± 0.02 cm2 V-1 s-1, 1.25 x 104 and 6.6 ± 0.79 V respectively. While changing the dielectric to sodium ss-alumina presented a µsat, Ion/Ioff ratio and Vth of 4.21 ± 0.18 cm2 V-1 s-1, 1.4 x 102 and 0.47 ± 0.08 V respectively. © Springer Science+Business Media, LLC, part of Springer Nature 2019.Item Combustion aided in situ consolidation of high strength porous ceramic structures with a minimum thermal budget(Elsevier B.V., 2020) Pujar, P.; Pal, A.; Mandal, S.The exothermic reaction between a pair of combustible pore formers (urea-ammonium nitrate) is the driving force in realizing low-temperature consolidation of hydroxyapatite (HA) particles. The particles are allowed to sinter in the proximity to the combustible pore formers. The exothermic (?H°rea = -898 kJ/mol) redox reaction between combustible pore formers is successfully utilized in deriving high compressive strength (~24 MPa) of HA at 300 °C. The evolution of gaseous products of combustion results in an interconnected porous network of HA. The estimated compressive strength of sintered HA at 300 °C is comparable with high temperature (1100 °C) conventionally sintered HA, at a fixed open porosity (~40%); which depicts nearly ~82% achievement with a reduction of sintering temperature by ~72%. Also, the pellets sintered at 600 °C have shown ~90% achievement in compressive strength of sintered HA. Further, the saturated pore area of 15% requires a sintering time of 9.58 h at a sintering temperature of 600 °C. Thus, combustion-assisted sintering is an alternative technique proves its potentiality in achieving remarkable compressive strength and paves the way for low-cost porous ceramics. © 2020 Elsevier B.V.Item Phase stabilized solution combustion processed (Ce0.2La0.2Pr0.2Sm0.2Y0.2)O1.6-δ: An exploration of the dielectric properties(Elsevier Ltd, 2023) Salian, A.; K, A.P.; Mandal, S.High entropy oxide (HEO) (Ce0.2La0.2Pr0.2Sm0.2Y0.2)O1.6-δ with a phase pure fluorite was synthesized using low-temperature solution combustion. A low-temperature formation of HEO was evidenced at 500 ºC. The HEO formation at 500 ºC was due to the exothermicity of the combustion redox reaction, where the internal temperature might have reached a much higher temperature for a limited amount of time. The presence of Sm2O3 and Y2O3 was visible upto 500 ºC, while La2O3 was detected up to 900 ºC and the HEO fully got stabilized at 1000 ºC with a single-phase, fcc fluorite structure with an Fm-3 m space group. The HEO displays one of its parent oxide Ce-O structural properties as both belong to the fluorite family and had lattice parameters very close to each other. The presence of a secondary phase in the 2 and 3-cation systems and the display of a single phase in the 4 and 5-cation systems indicated the role of configurational entropy in phase stabilization. Raman of HEO also affirmed the formation of HEO at 500 °C, the complete elimination of secondary phases at 1000 °C, and a fully disordered occupancy of various metal cations with severe lattice distortion. A Flake morphology with a nanogranular cluster on the surface was displayed. Dielectric measurements at room temperature showed permittivity (κ) ≈ 29 – 5.7 from 100 Hz to 1 MHz. © 2023 Elsevier B.V.