In this study, tin film was thermally evaporated onto a stainless steel substrate in an argon atmosphere. The tin films were then subjected to a DC plasma oxidation process using an oxygen/argon gas mixture. Three different substrate temperatures (100°C, 150°C, and 200°C) and three different oxygen partial pressures (12.5%, 25%, and 50%) were used to investigate the physical and microstructural properties of the films. The surface properties were studied by scanning electron microscopy, X-ray diffraction, atomic force microscopy and a four-point probe electrical resistivity measurement. The grain size and texture coefficient of the tin oxide films were calculated. Both SnO and SnO_2 films with grain sizes of 13-43 nm were produced, depending on the oxygen partial pressure. SnO films have flower- and flake-like nanostructures, and SnO_2 films have grape-like structures with nanograins. The resistivity values for the SnO_2 phase were found to be as low as 10^{-5} Ω cm and were observed to decrease with increasing substrate temperature.
In this study, tin/tinoxide (Sn/SnO_2) nanocomposites thin films were produced by thermal evaporation and plasma oxidation as anode materials for Li-ion batteries. To produce Sn/SnO_2 thin films, pure metallic tin (Sn) was thermally evaporated on the stainless steel substrates in argon atmosphere. The Sn films were subjected to plasma oxidation process at oxygen/argon gas mixture. Three different plasma oxidation times (30, 45, and 60 min) were used to investigate oxidation kinetics and physical and microstructural properties. The surface properties were studied by scanning electron microscopy and atomic force microscopy. For structural analysis, X-ray diffraction measurements were carried out. Sn/SnO_2 coated stainless steel substrates were used as the working electrode in coin-type (CR2016) test cells. The energy storage capacity Sn/SnO_2 electrodes were determined depending on the oxidation time and Sn:SnO_2 ratio.
In this study, free-standing zincoxide/multiwalled carbon nanotube nanocomposite was synthesized by a multistep technique. Buckypapers having controlled porosity were prepared by vacuum filtration from oxidized multiwalled carbon nanotubes. Zinc acetate dihydrate (ZnAc) (Zn(CH_3COO)_2 ·2H_2O) was used as zinc source and ethanol used as solvent. An appropriate amount of monoethanolamine was added to sol to change acid-base media. The solution was vacuum filtered through buckypaper and annealed at 350C in air. It was found that the zinc oxide grows around the multiwalled carbon nanotubes to form a uniform composite. Morphology of zine oxide/multiwalled carbon nanotube was also studied in detail. Nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy.
In this study, tin/tinoxide/multiwalled carbon nanotube (Sn/SnO_2/MWCNT) nanocomposites were produced as anode materials for Li-ion batteries by a two-step process. Metallic tin was evaporated onto free-standing MWCNT buckypapers having controlled porosity and subsequently rf plasma oxidized in Ar:O_2 (1:1) gas mixture. Besides, Sn/SnO_2 nanocomposites were produced in the same conditions onto stainless steel substrates to make a comparison. X-ray diffraction and scanning electron microscopy were used to determine the structure and morphology of the obtained nanocomposites. The discharge/charge tests, cyclic voltammetry and electrochemical impedance spectroscopy were carried out to characterize the electrochemical properties of these composites. Promising results were obtained in the tin based MWCNT nanocomposites for next-generation micro battery applications because of the high active surface area of the SnO_2/MWCNT core-shell structures.
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