Exploiting the Reactivity of Metal Trifluoroacetates to Access Alkali-Niobium(V) Oxyfluorides.

Motivated by the lack of facile routes to alkali-niobium(V) oxyfluorides KNbOF and CsNbOF, we investigated the reactivity of alkali trifluoroacetates KH(tfa) and CsH(tfa) (tfa = CFCOO) toward NbO in the solid state. Tetragonal tungsten bronze KNbOF and pyrochlore CsNbOF were obtained by simply reacting the corresponding trifluoroacetate with NbO at 600 °C under air, without the need for specialized containers or a controlled atmosphere. Thermolysis of KH(tfa) in the presence of NbO yielded single-phase polycrystalline KNbOF.

Effect of Relaxations on the Conductivity of La Li Ti Al O Fast Ion Conductors.

Perovskite-type solid-state electrolytes, Li La TiO (LLTO), are considered among the most promising candidates for the development of all-solid-state batteries based on lithium metal. Their high bulk ionic conductivity can be modulated by substituting part of the atoms hosted in the A- or B-site of the LLTO structure. In this work, we investigate the crystal structure and the long-range charge migration processes characterizing a family of perovskites with the general formula La Li Ti Al O (0 ≤ ≤ 0.

Coupled Compositional and Displacive Modulations in KLaMnWO Revealed by Atomic Resolution Imaging.

Complex compositional and displacive modulations of the crystal structure of KLaMnWO are imaged with atomic resolution by means of scanning transmission electron microscopy (STEM). This oxide is stabilized by cation vacancies leading to a LaKMnWO stoichiometry. Compositional modulation on both the K and La layers are revealed in the high-angle annular dark-field STEM (HAADF-STEM) images.

Structural Ordering Supremacy on the Oxygen Reduction Reaction of Layered Iron-Perovskites.

Layered perovskites of the GdBaCaFeO system show oxygen reduction reaction (ORR) activity. The layered crystal structure of these oxides is established by the interplay of the Gd, Ba, and Ca locations with the ordering of the coordination polyhedra of the Fe cations. Substitution of Gd by Ca increases the oxygen deficiency that is accommodated by the formation of layers of FeO-squared pyramids intercalated with A-O layers containing mainly Gd.

Organometallic-Derived Carbon (ODC)-Metal Nano-Oxide Composites as Improved Electrode Materials for Supercapacitors.

In the search for the new generation of electrochemical energy storage materials, a novel and straightforward synthetic route for porous carbons and metal oxide nanoparticle composites based on the chlorination of the organometallic compounds Ni(CH) and Mn(CHO) at moderate temperatures, followed by hydrothermal treatment, has been developed. Electrochemical measurements in a three-electrode configuration show that, in both composites NiO@ODC and MnO@ODC, a synergistic effect between the capacitive and pseudocapacitive energy storage mechanisms is observed, thereby improving their electrochemical performance vs pure carbon materials. Electrochemical evaluation of symmetric cells gave gravimetric capacitances of 124 and 130 F g for NiO@ODC and MnO@ODC, respectively.