ChemInform Abstract: System KF‐DyF₃

Abstract

Das Zustandsdiagramm des Titelsystems wird durch thermische, röntgenographische und IR‐spektroskopische Untersuchungen ermittelt.

Reversible Conversion Reactions with Lithium in Bismuth Oxyfluoride Nanocomposites

“…BiF 3 undergoes a phase transformation from a previously noted 8 Pnma orthorhombic phase to a P͑−3͒c1 tysonite phase ͑hexagonal͒. A BiO ␦ F 3−2␦ solid solution with a tysonite-like structure also exists 13,14 and is isostructural with the high-pressure form of BiF 3 . ␦ in BiO ␦ F 3−2␦ can be as low as 0.02; hence, although the high-energy milling was conducted under He, it is possible that some oxygen anions, present as an impurities, stabilized the tysonite form.…”

“…␦ in BiO ␦ F 3−2␦ can be as low as 0.02; hence, although the high-energy milling was conducted under He, it is possible that some oxygen anions, present as an impurities, stabilized the tysonite form. According to Ardashnikova et al, 14 a thermal treatment at 350°C in an inert atmosphere causes the metastable high-pressure fluoride to transform back into the orthorhombic form whereas the oxyfluoride remains stable. Our material did transform into orthorhombic BiF 3 during annealing, supporting the fact that this is indeed the high-pressure tysonite BiF 3 as opposed to the oxyfluoride.…”

“…In contrast, a tysonite phase can clearly be identified on the pattern of the cell cycled in LiPF 6 EC/DMC, despite the broadness of the peaks. The compound with the tysonite structure could either be the high-pressure hexagonal phase of BiF 3 14 or a low-oxygencontent bismuth oxyfluoride BiO ␦ F 3−2␦ with ␦ Ͻ 0.15. 13 No matter which one it is, the bismuth compound present is highly fluorinated and this implies that the LiPF 6 EC/DMC electrolyte is somehow involved in the chemical reaction at the end of the charge.…”

Operando Observations of Reversible α-BiF3 Conversion in Liquid Electrolyte by Synchrotron Radiation Diffraction and 7Li Nuclear Magnetic Resonance

“…Pure fluoride BiF 3 is known to transform to an orthorhombic structure upon annealing at 350 °C in an inert atmosphere. 14,31 The purpose of the addition of AB at the secondary stage of ball milling in the present study was to ensure that the AB effectively coated the ball-milled BiF 3 particle surfaces, allowing it to operate better as a conductive additive compared with the case of mixing afterward. During the milder ball milling at 600 rpm, the AB likely acted as a lubricant, which buffered frictional collisions, having a similar effect to moderately high-temperature (350 °C) annealing under the inert atmosphere.…”