Iron Oxide-Coupled Graphite/Fe–Si Steel Structure for Analog Computing from Recycling Principle

Analog computing from recycling principle for next circular economy scenario has been studied with an iron oxide-coupled graphite/Fe–Si steel structure which was built using recycled waste materials, such as lead pencil and 3% Si steel (Fe–Si steel) foils. Proximity phenomena, such as disordered structure of iron oxide and magnetostriction-induced conduction, inside graphite lattice resulted in functional properties to advance analog architectures. Thermal oxidation was the synthesis route to produce iron oxide as coating film on Fe–Si steel foil, whose structure properties were validated by Raman spectroscopy where phase formation of hematite, α-Fe2O3, resulted as iron oxide thin-film. Three graphite layers with different compositions were also analyzed by Raman spectroscopy and used for studying electrical conduction in Fe–Si steel/α-Fe2O3/graphite structure from current–voltage plots at room temperature.

Stress and Temperature Sensitivity of Photonic Crystals Resonant Cavity

The temperature and stress characteristic of photonic band gap structure resonant cavities with square and graphite lattice have been studied by finite-difference time-domain method. The results show that the resonant cavities, both square and graphite lattice, have more and more resonant frequency with the cavity enlarging. And the curves between the resonant frequency and stress have better linearity. When the cavity enlarges enough, the curve between resonant frequency and temperature will become sectionalized line from nonlinear curve. Especially, the temperature sensitivity will be descending as the cavity is enlarging. Nevertheless, once some structures are put in the center of the cavity, the temperature sensitivity will be rising fast for this kind of cavity. Obviously, this character is convenient for us to achieve the specification measurement for temperature and stress.

Study of molten Li2Co3 electrolysis as a method for production of carbon nanotubes

The production of carbon nanotubes (CNTs) by electrolysis in molten Li2CO3 was investigated by studying the effect of the electrolyte, temperature of the electrolyte and cathodic overpotential. Cyclic voltametry clearly shows that instead of the expected Li discharge of the cathode as a first reaction, some early electrochemical reaction starts at a potential of –0.1 V, as a result of which, instead of the expected process of intercalation into the graphite lattice and CNTs formation, deposition of carbon occurs with the graphite cathode acting as the substrate. The carbon deposit obtained during the process of electrolysis together with the solidified salt, after dissolving in water, filtering and drying, was inspected with scanning electron microscopy (SEM). The results show that, among the observed structures and impurities, there are no CNTs. The morphology of the product is different from others previously observed, with a shape like sheets of flowers, and very small nano-balls. The impurities are metal particles from the salt and the impurities originating from the salt. For better understanding and confirmation of these result, cyclic voltametry and electrolytic deposition of carbon on a molybdenum electrode was also investigated. Molten LiCl was used as a base electrolyte with adding of 1, 5 and 10 % of Li2CO3. SEM observations and cyclic voltammograms confirm that under those conditions a process of carbon deposition occurs.