LiCo1−yMyO2 positive electrodes for rechargeable lithium batteries: II. Nickel substituted materials grown by the citrate method

[Abstract] The layered LiCo1−yNiyO2 microcrystalline powders were synthesized by a sol–gel method using citric acid as a chelating agent in the range 0.2 ≤ y ≤ 0.8. Submicron-sized particles of the precursor were obtained at temperature below 400 °C and microcrystalline powders were grown by thermal treatment at 700 °C for 5 h in air. The carboxylic-based acid functioned such as a fuel, decomposed the homogeneous precipitate of metal complexes at low temperature, and yielded the free impurity LiCo1−yNiyO2 single-phases suitable for electrochemical applications. The synthesized products were characterized by structural, spectroscopic and thermal analyses. FT-IR measurements provide information on the growth process and the final local environment in the cationic sublattice of LiCo1−yNiyO2 solid solution. The electrochemical performance of the synthesized products in rechargeable Li cells was evaluated using non-aqueous solution 1 M LiPF6 in EC-DMC as electrolyte. The electrochemical features of a series of LiCo1−yNiyO2 compounds (0.2 ≤ y ≤ 1.0) are discussed in relation with their synthesis procedure and substitutive amount. The substitution of Ni3+ for Co3+ in LiCo1−yNiyO2 for y = 0.75 shows improvement of the specific capacity at ca. 187 mAh/g upon 32 cycles

Water-mediated structuring of bone apatite

International audienceIt is well known that organic molecules from the vertebrate extracellular matrix of calcifying tissues are essential in structuring the apatite mineral. Here, we show that water also plays a structuring role. By using solid-state nuclear magnetic resonance, wide-angle X-ray scattering and cryogenic transmission electron microscopy to characterize the structure and organization of crystalline and biomimetic apatite nanoparticles as well as intact bone samples, we demonstrate that water orients apatite crystals through an amorphous calcium phosphate-like layer that coats the crystalline core of bone apatite. This disordered layer is reminiscent of those found around the crystalline core of calcified biominerals in various natural composite materials in vivo. This work provides an extended local model of bone biomineralization

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

Cosmic ray oriented performance studies for the JEM-EUSO first level trigger

JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 ⋅ 1019 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics

Effect of an 8-week combined weights and plyometrics training program on golf drive performance.

The nature of the crystalline phase present in gallium oxide films grown by pulsed-laser deposition on c-cut sapphire substrate has been studied. Amorphous, polycrystalline or epitaxial gallium oxide films can be obtained depending upon the oxygen pressure during the growth in the 400–500 °C temperature range. Detailed pole figure measurements on epitaxial films demonstrate that the monoclinic β-Ga2O3 phase grows epitaxially on c-cut sapphire substrates at T = 500 °C under a 10− 5 mbar oxygen pressure. Two distinct textures were evidenced, i.e., the ( 2¯01) and (101) planes of the monoclinic β-Ga2O3 phase being parallel to the c-cut sapphire substrates. The corresponding epitaxial relationships were determined and interpreted in the frame of the domain matching epitaxy. The differences in the two textures were correlated to the various atomic configurations in the ( 2¯01) and (101) planes of the monoclinic β-Ga2O3 phase

Impact Testing of Airport Approach Lighting Towers

NRC publication: Ye