Faculty Publications
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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 Effect of annealing-temperature-assisted phase evolution on conductivity of solution combustion processed calcium vanadium oxide films(Springer, 2018) Manjunath, G.; Vardhan, R.V.; Salian, A.; Jagannatha, R.; Kedia, M.; Mandal, S.In thiswork, the effect of annealing temperature on the conductivity of solution-combustion-synthesized calcium vanadium oxide (CVO) films was studied. Conductivity was tailored by the appearance of the phases like CaVO3, CaV2O5 and Ca2V2O7 as a function of annealing temperature; CaVO3 and CaV2O5 are responsible for high conductivity, whereas V5+ presence in Ca2V2O7 contributes towards dielectric nature. Evolution of phases of CVO was identified through X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A detailed conductivity measurement as a function of annealing temperature helps us to identify the decreasing trend of conductivity with increasing temperature up to 400°C; beyond this it behaves like an insulator. There was a stable conductivity while aging the films in ambient for a few days. This study revealed safe application temperature domain of CVO, and a clear correlation of electrical conductivity with the in-depth structural-compositional-morphological study. © Indian Academy of Sciences.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.