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Lithium-ion batteries dominate the battery field, particularly for electric and hybrid vehicles. Monoclinic Li3V2(PO4)3 has emerged as one of the most promising candidates for the cathode in lithium-ion batteries, offering better environmental safety and lower cost than competing materials. We have used in situ X-ray absorption spectroscopy to characterize the evolution of the vanadium in a Li3V2(PO4)3 cathode as it is cycled electrochemically. These data demonstrate the presence of significant kinetic effects such that the measured electrochemical behavior does not represent the bulk vanadium. When the cell is cycled between 3 and 4.5 V, there are two distinct vanadium species. When the potential is raised above 4.5 V, a third species is observed, consistent with formation of V5+. XANES data for the cathode after 3-4.8 V cycling are consistent with a severely distorted vanadium site, suggesting that lithium-vanadium antisite mixing may be responsible for the electrochemical irreversibility that is seen above 4.5 V.

Recently, amorphous/disordered oxide thin films made from Fe and lanthanides like Dy and Tb have been reported to have a rich set of magnetic, optical, and electronic properties, as well as room-temperature magneto-electric coupling with multiferroics [A. Malasi et al., Sci. Rep. 5, 18157 (2015); H. Taz et al., Sci. Rep. 6, 27869 (2016); and H. Taz et al., Sci. Rep. 10, 1–10 (2020)]. Here, we report the synthesis and detailed characterization of Fe 2.75 Dy-oxide thin films prepared on various substrates using electron beam co-evaporation. The structure, chemistry, electric, magnetic, and optical properties were studied for the as-prepared and annealed (373 K, in air, 1 h) films of thickness 40 nm. High resolution transmission electron microscopy and electron diffraction study showed that the films were amorphous in both the as-prepared and annealed states. The electron energy-loss spectroscopy studies quantified that metal oxygen stoichiometry changed from Fe 2.75 Dy-O 1.5 to Fe 2.75 Dy-O 1.7 upon annealing. Synchrotron-based x-ray absorption spectroscopy investigation confirmed that the as-prepared films were highly disordered with predominantly metallic Fe and Dy states that became slightly oxidized with annealing in air. The as-prepared amorphous films demonstrated significantly high value of ordinary (∼ 10 cm 2 /V s) and anomalous (∼ 10 2 cm 2 /V s) Hall mobility and high electrical conductivity of ∼ 10 3 S/cm at room temperature. The cryogenic magnetic property measurement shows two-step magnetization below 200 K, suggesting exchange-spring magnetic interaction. The nature of the field cooled and zero-field cooled curves suggested a spin-glass like transition between 78 K and 80 K, with a characteristic broad peak. The Tauc plot analysis from optical transmission spectra confirms the existence of an optical bandgap of ∼ 2.42 eV that increased slightly to ∼ 2.48 eV upon annealing. This rich set of transport, optical, and magnetic properties in these thin films is very exciting and points to potential applicability in low-cost multifunctional devices requiring a combination of transparent, semiconducting, and magnetic responses, such as in spintronics. [ABSTRACT FROM AUTHOR]

Polarized time-resolved X-ray absorption near edge structure (XANES) is used to characterize the sequential ballistic excited state dynamics of two B12 vitamers: cyanocobalamin and adenosylcobalamin. Excitation at 550 nm and 365 nm is used to resolve axial and equatorial contributions to the excited state dynamics.

This article presents a case study exploring the use of a student coding camp as a bottom-up mobile design process to generate library mobile apps. A code camp sources student programmer talent and ideas for designing software services and features. This case study reviews process, outcomes, and next steps in mobile web app coding camps. It concludes by offering implications for services design beyond the local camp presented in this study. By understanding how patrons expect to integrate library services and resources into their use of mobile devices, librarians can better design the user experience for this environment., INTRODUCTION Mobile applications offer an exciting opportunity for libraries to expand the reach of their services, to build new connections, and to offer unique, previously unavailable services for their users. [...]