Investigating the Cycling Stability of Fe2WO6 Pseudocapacitive Electrode Materials

The stability upon cycling of Fe2WO6 used as a negative electrode material for electrochemical capacitors was investigated. The material was synthesized using low temperature conditions for the first time (220 °C). The electrochemical study of Fe2WO6 in a 5 M LiNO3 aqueous electrolyte led to a specific and volumetric capacitance of 38 F g−1 and 240 F cm−3 when cycled at 2 mV·s−1, respectively, associated with a minor capacitance loss after 10,000 cycles. In order to investigate this very good cycling stability, both surface and bulk characterization techniques (such as Transmission Electron Microscopy, Mössbauer spectroscopy, and magnetization measurements) were used. Only a slight disordering of the Fe3+ cations was observed in the structure, explaining the good stability of the Fe2WO6 upon cycling. This study adds another pseudocapacitive material to the short list of compounds that exhibit such a behavior up to now.

New Insights into Sulfide Inclusions in 1018 Carbon Steels

The role of heterogeneous phases in the localized corrosion of materials is an emerging area of research. This work addresses the detrimental role MnS inclusions play in the localized corrosion of carbon steels. We report the results of surface and bulk characterization of MnS inclusions in 1018 carbon steel, using a high-resolution integrated Auger nanoprobe. It is shown that the surface morphology and composition of the inclusions are highly heterogeneous. MnS inclusions are found to be nonstoichiometric and to contain a highly O-enriched surface layer. Some inclusions are covered with a thin (approximately 5 nm) layer of Cu2S. The bulk composition of “MnS” inclusions is found to include 5–7% Fe and O, and these inclusions are believed to occupy Mn and S positions within the “MnS” lattice. Interfaces between “MnS” and host ferric grains are highly disordered. We hypothesize that pitting initiates and develops at these interfaces through a galvanic coupling between the strained and the unstrained ferrite grains.

Study of 14N(ρ,γ)15O resonance reaction at Eplab= 278 keV

An implanted target (14N on Ta) is prepared and characterized via surface and bulk characterization processes. The depth profile of the implanted ions is obtained experimentally by populating a narrow resonance state of 15O through 14N(ρ,γ) reaction induced with a laboratory proton energy of 278 keV. The experimental profile is then compared with devoted simulations to under- stand the locations of the implantated ions in the lattice structure. Later, the lifetimes of a few excited states of 15O, relevant for applications in astrophys- ical scenario, have been determined using Doppler Shift Attenuation Method(DSAM).