Browsing by Author "Gupta, B."
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Item Development of low temperature stoichiometric solution combustion derived transparent conductive ternary zinc tin co-doped indium oxide electrodes(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 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 Effect of O2, N2 and H2 on annealing of pad printed high conductive Ag-Cu nano-alloy electrodes(2018) Manjunath, G.; Anusha, P.; Salian, A.; Gupta, B.; Mandal, S.In this study, annealing of pad printed Ag-Cu based conducting ink was studied in oxidizing, inert and reducing atmosphere to verify its oxidation dependent conductivity. Ag-Cu manually was formulated adopting polyol method; where silver nitrate and copper nitrate serve as initial metal precursors. Polyvinylpyrrolidone (PVP), ethylene glycol and sodium borohydride act as a stabilizer, solvent and reducing agent respectively. The nanoalloys were with an average particle size ?48 15 nm, capped with polyvinylpyrrolidone to avoid agglomeration and stable in non-polar solvents. Formation of nanoalloy, Ag 90 wt%-Cu 10 wt%, was verified through a peak shift in UV-visible spectroscopy, found at 470 nm along with Nelson-Relay curve fitting and x-ray photoelectron spectroscopy study. The calculated lattice parameter of nanoalloy ?4.034 , was in between pure silver and copper. The crystallite size was calculated using Debye-Scherrer, Williamson-Hall isotropic strain model and Halder-Wagner method. Electrode patterns were printed on a glass substrate by pad printing and were annealed under O2, N2 and H2 atmosphere to study the oxidation kinetics of copper. A maximum conductivity of -6.6 ;105 S m-1 was observed in inert atmosphere annealing as the conductivity is solely depends on the oxidation of copper; appears with uttermost Cu0 and least Cu2+ in x-ray photoelectron spectroscopy. High conductive space required between manually and dispersion ink can have a potential application as an electrode in printed electronics. Further refinement of size of the nanopaticles by polyol method could help to obtain the effect of quantum confinement. 2018 IOP Publishing Ltd.Item Effect of O2, N2 and H2 on annealing of pad printed high conductive Ag-Cu nano-alloy electrodes(Institute of Physics Publishing helen.craven@iop.org, 2018) Manjunath, G.; Anusha, P.; Salian, A.; Gupta, B.; Mandal, S.In this study, annealing of pad printed Ag-Cu based conducting ink was studied in oxidizing, inert and reducing atmosphere to verify its oxidation dependent conductivity. Ag-Cu manually was formulated adopting polyol method; where silver nitrate and copper nitrate serve as initial metal precursors. Polyvinylpyrrolidone (PVP), ethylene glycol and sodium borohydride act as a stabilizer, solvent and reducing agent respectively. The nanoalloys were with an average particle size ?48 ±15 nm, capped with polyvinylpyrrolidone to avoid agglomeration and stable in non-polar solvents. Formation of nanoalloy, Ag 90 wt%-Cu 10 wt%, was verified through a peak shift in UV-visible spectroscopy, found at 470 nm along with Nelson-Relay curve fitting and x-ray photoelectron spectroscopy study. The calculated lattice parameter of nanoalloy ?4.034 Å, was in between pure silver and copper. The crystallite size was calculated using Debye-Scherrer, Williamson-Hall isotropic strain model and Halder-Wagner method. Electrode patterns were printed on a glass substrate by pad printing and were annealed under O2, N2 and H2 atmosphere to study the oxidation kinetics of copper. A maximum conductivity of -6.6 ×;105 S m-1 was observed in inert atmosphere annealing as the conductivity is solely depends on the oxidation of copper; appears with uttermost Cu0 and least Cu2+ in x-ray photoelectron spectroscopy. High conductive space required between manually and dispersion ink can have a potential application as an electrode in printed electronics. Further refinement of size of the nanopaticles by polyol method could help to obtain the effect of quantum confinement. © 2018 IOP Publishing Ltd.Item Low-temperature reducible particle-free screen-printable silver ink for the fabrication of high conductive electrodes(2019) Manjunath, G.; Pujar, P.; Gupta, B.; Gupta, D.; Mandal, S.In this contribution, screen printing of aqueous based particle-free silver ink is addressed using combustion chemistry, where inks embody a redox mixture of silver nitrate and citric acid in the presence of a binder, sodium-carboxymethylcellulose. The exothermic reaction at ~ 176 C results in the formation of pure silver. Screen-printing process is optimized for three different silver loadings (14%, 18% and 22%) in ink. In depth rheological study of the inks reveals thixotropic nature and the ink with 18% of silver possessing a viscosity of 328 Pa.s has a recovery rate of 84% at 110 s with a shear rate of 1 s?1. The deposited silver films (~ 3 m thick) on both rigid-glass and flexible-polyamide substrates have shown an electrical conductivity of 4.2 106 S m?1 and 2.6 106 S m?1 respectively. Film adhesion on glass substrates categorized under 3B as per ASTM D-3359. Present screen-printed silver films find their application as a gate electrode in thin film transistors (TFTs). The TFTs comprising of indium zinc tin oxide semiconductor and sodium ? -alumina dielectric with screen-printed silver as a gate electrode exhibited the saturation mobility, on:off ratio and threshold voltage of 0.88 cm2 V?1 s?1, 102 and ~ 0.3 V respectively. 2019, Springer Science+Business Media, LLC, part of Springer Nature.Item Low-temperature reducible particle-free screen-printable silver ink for the fabrication of high conductive electrodes(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Manjunath, G.; Pujar, P.; Gupta, B.; Gupta, D.; Mandal, S.In this contribution, screen printing of aqueous based particle-free silver ink is addressed using combustion chemistry, where inks embody a redox mixture of silver nitrate and citric acid in the presence of a binder, sodium-carboxymethylcellulose. The exothermic reaction at ~ 176 °C results in the formation of pure silver. Screen-printing process is optimized for three different silver loadings (14%, 18% and 22%) in ink. In depth rheological study of the inks reveals thixotropic nature and the ink with 18% of silver possessing a viscosity of 328 Pa.s has a recovery rate of 84% at 110 s with a shear rate of 1 s?1. The deposited silver films (~ 3 µm thick) on both rigid-glass and flexible-polyamide substrates have shown an electrical conductivity of 4.2 × 106 S m?1 and 2.6 × 106 S m?1 respectively. Film adhesion on glass substrates categorized under 3B as per ASTM D-3359. Present screen-printed silver films find their application as a gate electrode in thin film transistors (TFTs). The TFTs comprising of indium zinc tin oxide–semiconductor and sodium ? -alumina dielectric with screen-printed silver as a gate electrode exhibited the saturation mobility, on:off ratio and threshold voltage of 0.88 cm2 V?1 s?1, 102 and ~ 0.3 V respectively. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.Item Retention of high dielectric constant sodium beta alumina via solution combustion: Role of aluminum ions complexation with fuel(2018) Gupta, B.; Pujar, P.; Mal, S.S.; Gupta, D.; Mandal, S.In the present study, solution combustion technique has been explored to synthesize Sodium ?-alumina (SBA; NaAl11O17) powder and thin films. Three fuels namely urea, glycine and citric acid have been used to seek the feasibility of synthesizing crystalline SBA powder at low temperature. Also, the effect of nature of fuels used as well as calcination treatment on phase evolution and morphology of the as-combusted powder was investigated. Thermal analysis and X-ray diffraction studies suggest the formation of crystalline SBA powder at temperature as low as 259 C, using urea in the combustion reaction whereas other fuels resulted in amorphous SBA phase and this variation in phase was found due to difference in exothermicity of the fuel used. Thermodynamic and spectroscopic analyses showed that the exothermicity of fuel depends on various factors like (i) standard heat of formation of fuel and (ii) the complexation offered by fuel to metal cations. Furthermore, sodium ?-alumina thin film capacitor (metal-insulator-metal) was also fabricated using urea via spray combustion synthesis. The sodium ?-alumina thin film showed a high dielectric value (?r) of ~21. 2017 Elsevier Ltd and Techna Group S.r.l.Item Retention of high dielectric constant sodium beta alumina via solution combustion: Role of aluminum ions complexation with fuel(Elsevier Ltd, 2018) Gupta, B.; Pujar, P.; Mal, S.S.; Gupta, D.; Mandal, S.In the present study, solution combustion technique has been explored to synthesize Sodium ?-alumina (SBA; NaAl11O17) powder and thin films. Three fuels namely urea, glycine and citric acid have been used to seek the feasibility of synthesizing crystalline SBA powder at low temperature. Also, the effect of nature of fuels used as well as calcination treatment on phase evolution and morphology of the as-combusted powder was investigated. Thermal analysis and X-ray diffraction studies suggest the formation of crystalline SBA powder at temperature as low as 259 °C, using urea in the combustion reaction whereas other fuels resulted in amorphous SBA phase and this variation in phase was found due to difference in exothermicity of the fuel used. Thermodynamic and spectroscopic analyses showed that the exothermicity of fuel depends on various factors like (i) standard heat of formation of fuel and (ii) the complexation offered by fuel to metal cations. Furthermore, sodium ?-alumina thin film capacitor (metal-insulator-metal) was also fabricated using urea via spray combustion synthesis. The sodium ?-alumina thin film showed a high dielectric value (?r) of ~21. © 2017 Elsevier Ltd and Techna Group S.r.l.Item Sodium ion incorporated alumina - A versatile anisotropic ceramic(Elsevier Ltd, 2019) Pujar, P.; Gupta, B.; Sengupta, P.; Gupta, D.; Mandal, S.The present article is a review of crystal structure dependent anisotropic properties of β and β″-phases of sodium ion incorporated alumina. The anisotropy in electrical properties such as ionic conductivity and dielectric permittivity is due to the layered structure. Conducting plane between two consecutive spinel aluminas constituting loosely bound mobile sodium ions, promote ionic conductivity in the parallel direction. In contrary, the restricted movement of ions in the orthogonal direction brings about polarization giving it directional dielectric property. High ionic conductivity of 1.3 S/cm and large dielectric constant of ˜ 200 are reported. Exchanging sodium ions with different cations, such as potassium and lithium, results in similar anisotropy. The processing of β and β″-phases along with metastability of intermediate mullite phase is described in the current review. In addition, the applications of sodium ion incorporated aluminas, such as solid electrolyte in batteries, thin film transistors and gas sensors are discussed. © 2019 Elsevier LtdItem Sodium ion incorporated alumina - A versatile anisotropic ceramic(Elsevier Ltd, 2019) Pujar, P.; Gupta, B.; Sengupta, P.; Gupta, D.; Mandal, S.The present article is a review of crystal structure dependent anisotropic properties of β and β″-phases of sodium ion incorporated alumina. The anisotropy in electrical properties such as ionic conductivity and dielectric permittivity is due to the layered structure. Conducting plane between two consecutive spinel aluminas constituting loosely bound mobile sodium ions, promote ionic conductivity in the parallel direction. In contrary, the restricted movement of ions in the orthogonal direction brings about polarization giving it directional dielectric property. High ionic conductivity of 1.3 S/cm and large dielectric constant of Ëœ 200 are reported. Exchanging sodium ions with different cations, such as potassium and lithium, results in similar anisotropy. The processing of β and β″-phases along with metastability of intermediate mullite phase is described in the current review. In addition, the applications of sodium ion incorporated aluminas, such as solid electrolyte in batteries, thin film transistors and gas sensors are discussed. © 2019 Elsevier Ltd