• L S ROMAN

Articles written in Bulletin of Materials Science

• Tin oxide as a transparent electrode material for light-emitting diodes fabricated with poly (p-phenylene vinylene)

We have fabricated light emitting diodes (LED) with poly (p-phenylene vinylene) (PPV) as the emissive layer and tin oxide (TO) as the transparent conducting positive electrode and aluminium as the negative electrode. The fabrication conditions are optimized for visible light emission in these TO/PPV/Al LEDs. The threshold voltage for substantial charge injection for visible light emission in these LEDs lies below 10V. The device fabrication and electrical characterization of TO/PPV/Al LEDs are discussed in this communication.

• High-energy ball milling synthesis of N-doped graphite/PbO and ZnO composites for lead-acid battery application

In order to improve the electrical efficiency of lead-acid batteries under partial state of charge, three additives for the negative active mass were synthesized by high-energy ball milling: (1) exfoliated graphite doped with nitrogen groups (GN) from urea and novel (2) ZnO/GN and (3) PbO/GN. The main variables of grinding medium, ball sizes and time were studied. All additives were characterized on Raman, X-ray diffraction (XRD) and scanning electron microscopy and pure, uniform composites of particle size${\le}$3 ${\mu}$m were demonstrably obtained. The optimized samples proceeded to electrochemical tests. Particularly, selected PbO/GN4-5 provided a 41% reduction in the current density for the H$_2$ evolution reaction at the working potential on linear sweep voltammetry tests. The produced additives indicated high charge efficiency on the formation process of a 2 V, 36 Ah lead-acid cell. Cycle life performances of cells containing 0.50% (vs. LO) of selected GN4, PbO/GN4-5 and ZnO/GN4-5 surpassed that of commercial graphite, in 75, 328 and 752%, respectively. As a result, the produced additives represent a progress in enhancing commercial additives. The effects of these additives were further investigated after the teardown of the cells. The negative plate was pointed out to be the limiting factor and there is evidence that the additives provided a more uniform distribution and reduced the size of the PbSO$_4$ crystals.

• # Bulletin of Materials Science

Volume 46, 2023
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Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020