α-Ba2P2O7

Single crystals of α-Ba2P2O7, dibarium diphosphate, were obtained by solid-state reaction. The ortho­rhom­bic structure is isotypic with α-Sr2P2O7 and is the second polymorph obtained for this composition. The structure is built from two different BaO9 polyhedra (both with m symmetry), with Ba—O distances in the ranges 2.7585 (10)–3.0850 (6) and 2.5794 (13)–2.9313 (4) Å. These polyhedra are further linked by sharing corners along [010] and either edges or triangular faces perpendicularly to [010] to form the three-dimensional framework. This polyhedral linkage delimits large channels parallel to [010] where the P2O7 diphosphate anions are located. These groups (symmetry m) are characterized by a P—O—P angle of 131.52 (9)° and an eclipsed conformation. They are connected to the BaO9 polyhedra through edges and corners

Lithium cobalt(II) pyrophosphate, Li1.86CoP2O7, from synchrotron X-ray powder data

Structure refinement of high-resolution X-ray powder diffraction data of the title compound gave the composition Li1.865CoP2O7, which is also verified by the ICP measurement. Two Co sites exist in the structure: one is a CoO5 square pyramid and the other is a CoO6 octa­hedron. They share edges and are further inter­connected through P2O7 groups, forming a three-dimensional framework, which exhibits different kinds of inter­secting tunnels containing Li cations and could be of great inter­est in Li ion battery chemistry. The structure also exhibits cation disorder with 13.5% Co residing at the lithium (Li1) site. Co seems to have an average oxidation state of 2.135, as obtained from the strutural stochiometry that closely supports the magnetic susceptibility findings

Réflexion stratégique sur le positionnement des antiarythmiques face à la prise en charge non pharmacologique de la fibrillation auriculaire

BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Na2FeP2O7 as a Promising Iron-Based Pyrophosphate Cathode for Sodium Rechargeable Batteries: A Combined Experimental and Theoretical Study

Considering the promising electrochemical performance of the recently reported pyrophosphate family in lithium ion batteries as well as the increasing importance of sodium ion batteries (SIBs) for emerging large-scale applications, here, the crystal structure, electrochemical properties, and thermal stability of Na2FeP2O7, the first example ever reported in the pyrophosphate family for SIBs, are investigated. Na2FeP2O7 maintains well-defined channel structures (triclinic framework under the P1 space group) and exhibits a reversible capacity of ?90 mAh g?1 with good cycling performance. Both quasi-equilibrium measurements and first-principles calculations consistently indicate that Na2FeP2O7 undergoes two kinds of reactions over the entire voltage range of 2.0�4.5 V (vs Na/Na+): a single-phase reaction around 2.5 V and a series of two-phase reactions in the voltage range of 3.0�3.25 V. Na2FeP2O7 shows excellent thermal stability up to 500 �C, even in the partially desodiated state (NaFeP2O7), which suggests its safe character, a property that is very critical for large-scale battery applications.Wiley Online Librar

LiCo2As3O10: une nouvelle structure à tunnels interconnectés

The title compound, lithium dicobalt(II) triarsenate, LiCo2As3O10, was synthesized by a solid-state reaction. The As atoms and four out of seven O atoms lie on special positions, all with site symmetry m. The Li atoms are disordered over two independent special (site symmetry -1) and general positions with occupancies of 0.54 (7) and 0.23 (4), respectively. The structure model is supported by bond-valence-sum (BVS) and charge-distribution (CHARDI) methods. The structure can be described as a three-dimensional framework constructed from bi-octahedral Co2O10 dimers edge-connected to As3O10 groups. It delimits two sets of tunnels, running parallel to the a and b axes, the latter being the larger. The Li+ ions are located within the intersections of the tunnels. The possible motion of the alkali cations has been investigated by means of the BVS model. This simulation shows that the Li+ motion appears to be easier mainly along the b-axis direction and that this material may possess interesting conduction properties