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The role of the perovskite lattice oxygen in the oxygen evolution reaction (OER) is systematically studied in the PrBaCo2O5+δ family. The reduced number of physical/chemical variables combined with in-depth characterizations such as neutron dif-fraction, O K-edge X-ray absorption spectroscopy (XAS), electron energy loss spectroscopy (EELS), magnetization and scanning transmission electron microscopy (STEM) studies, helps investigating the complex correlation between OER activity and a single perovskite property, such as the oxygen content. Larger amount of oxygen vacancies appears to facilitate the OER, possibly contributing to the mechanism involving the oxidation of lattice oxygen, i.e., the lattice oxygen evolution reaction (LOER). Furthermore, not only the number of vacancies but also their local arrangement in the perovskite lattice influences the OER activity, with a clear drop for the more stable, ordered stoichiometry., The X-ray absorption measurements were performed on the EPFL/PSI X-Treme beamline (O K-edge) and at the SuperXAS beamline (Co K-edge) at the Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland. The diffraction measurements were performed at the HRPT instrument at the Swiss spallation neutron source SINQ and at the MS-beamline at the Swiss Light Source at the Paul Scherrer Institute. The authors acknowledge the MS team for the measurements (Mesquik proposal 20182326). J.G. acknowledges Ramón y Cajal contract RYC-2012-11709 and the Severo Ochoa SEV-2015-0496 Project. The authors acknowledge the ICTS-CNME at UCM for offering access to their instruments and expertise and the Paul Scherrer Institute, for financial support through the internal CROSS project. T.J.S. thanks Innosuisse and the Swiss Competence Centre for Energy Research (SCCER) Heat & Electricity Storage.

International audience; An organic, cheap and environmental friendly salt, namely disodium rhodizonate Na2C6O6, is tested as Na sacrificial template in a full-cell sodium-ion battery employing a sodium deficient P2 phase, Na0.67Mn0.6Fe0.25Co0.15O2 (NaMFC) as cathode, and a carbonaceous material as counter electrode. As a proof of concept, we demonstrated that the decomposition of the sacrificial organic material leads to enhance the specific capacity in the full-cell system, but the electrochemical results are mitigated by the high irreversibility caused by the side products coming from the sacrificial template decomposition. The mechanism of decomposition of the organic additive as well as its impact on the reaction mechanisms are investigated by online electrochemical mass spectroscopy (OEMS), microscopy and Raman/Infrared vibrational spectroscopy. Additionally, operando X-ray diffraction (XRD) demonstrates that during the oxidation of the disodium rhodizonate, the P2-phase undergoes a re-sodiation, which explains the benefit of Na2C6O6 as Na reservoir.

P2–Na0.67Mn0.6Fe0.25Al0.15O2 (NaMFA) was developed as a cheaper and less-toxic cathode material for sodium-ion batteries than the Co analogous, P2–Na0.67Mn0.6Fe0.25Co0.15O2 (NaMFC). Despite cobalt ...

International audience; Due to the toxicity and price of cobalt (Co), Na0.67MnxFeyCozO2 (NaMFC) was tested as a cathode material for Na-ion batteries with lower cobalt contents. The objective was to set the Co to a maximum of 0.15 and compensate its loss by changing the ratio of Mn or Fe. The synthesized compounds were compared to two reference materials Na0.67Mn0.5Fe0.25Co0.25O2 and Na0.67Mn0.5Fe0.5O2. Microscopy (SEM), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and electrochemical tests were performed to characterize the pristine samples and to understand the impact of the cobalt on the electrochemical mechanism. A link was established between the amount of Co in the NaMFC material and the oxidation state of the Mn in the discharged sample. We confirmed that the role of the cobalt is to prevent a high Mn(III) ratio in the compound and thus help to limit the fading of the electrochemical performance. The compound Na0.67Mn0.5Fe0.35Co0.15O2 offers a good compromise between electrochemical stability and lower Co content.

ZnNi(CN)4 is a 3-D framework material consisting of two interpenetrating PtS-type networks in which tetrahedral [ZnN4] units are linked by square-planar [NiC4] units. Both the parent compounds, cubic Zn(CN)2 and layered Ni(CN)2, are known to exhibit 3-D and 2-D negative thermal expansion (NTE), respectively. Temperature-dependent inelastic neutron scattering (INS) measurements were performed on a powdered sample of ZnNi(CN)4 to probe phonon dynamics. The measurements were underpinned by ab-initio lattice dynamical calculations. Good agreement was found between the measured and calculated generalized phonon density-of-states, validating our theoretical model and indicating that it is a good representation of the dynamics of the structural units. The calculated linear thermal expansion coefficients are αa = -21.2 × 10-6 K-1 and αc = +14.6 × 10-6 K-1, leading to an overall volume expansion coefficient, αV of -26.95 × 10-6 K-1, pointing towards pronounced NTE behaviour. Analysis of the derived mode-Gruneisen parameters shows that the optic modes around 12 and 40 meV make a significant contribution to the NTE. These modes involve localised rotational motions of the [NiC4] and/or [ZnN4] rigid units, echoing what has previously been observed in Zn(CN)2 and Ni(CN)2. However, in ZnNi(CN)4, modes below 10 meV have the most negative Gruneisen parameters. Analysis of their eigenvectors reveals that a large transverse motion of the Ni atom in the direction perpendicular to its square-planar environment induces a distortion of the units. This mode is a consequence of the Ni atom being constrained only in two dimensions within a 3-D framework. Hence, although rigid-unit modes account for some of the NTE-driving phonons, the added degree of freedom compared with Zn(CN)2 results in modes with twisting motions, capable of inducing greater NTE.

Density Functional Theory (DFT) has proven to be an invaluable and effective tool for identifying highly active electrocatalysts for the oxygen evolution reaction (OER). Herein we take a computational approach in order to first identify a series of rare-earth pyrochlore oxides based on Ir and Ru as potential OER catalysts. The DFT-based phase diagrams, Pourbaix diagrams (E vs. pH), projected density of states (PDOS), and band energy diagrams were used to identify prospective OER catalysts based on rare earth Ir and Ru pyrochlores. The predicted materials were synthesized using the spray-freeze freeze-drying approach to afford nanoparticulate oxides conforming to the pyrochlore structural type A2B2O7 where A = Nd, Gd, or Yb and B = Ir or Ru. In agreement with the computed Pourbaix diagrams, the materials were found to be moderately stable under OER conditions. All prepared materials show higher stability as compared to the benchmark IrO2 catalyst and the OER mass activity of Yb2Ir2O7 and the ruthenate pyrochlores (Nd2Ru2O7, Gd2Ru2O7, and Yb2Ru2O7) were also found to exceed that of the benchmark IrO2 catalyst. We find that the OER activity of each pyrochlore series (i.e. iridate or ruthenate) generally improves as the size of the A-site cation decreases, indicating that maintaining control over the local structure can be used to influence the electrocatalytic properties.

Layered copper-nickel cyanide, CuNi(CN)4, a 2-D negative thermal expansion material, is one of a series of copper(ii)-containing cyanides derived from Ni(CN)2. In CuNi(CN)4, unlike in Ni(CN)2, the cyanide groups are ordered generating square-planar Ni(CN)4 and Cu(NC)4 units. The adoption of square-planar geometry by Cu(ii) in an extended solid is very unusual.

Aqueous binders are highly recommended in battery production for (i) reducing the costs and, (ii) increasing the safety due to the absence of an organic solvent. Unfortunately, the impact of water during the electrode formulation on sodiated phases is still unclear and deserves investigation. In this work, we used carboxymethylcellulose (Na-CMC) binder to prepare electrodes of a high energy density P2-layered oxide material, Na0.67Mn0.6Fe0.25Co0.1502 (NaMFC). We investigated the effects of water-based electrode preparation on the electrochemical performance, by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and neutron diffraction. The water leads to degradation of the material limiting the reversible specific charge at 90 mAh&middot, g&minus, 1 instead of 120 mAh&middot, 1 obtained with N-methyl pyrrolidone (NMP) solvent with polyvinylidene fluoride (PVDF) as binder. The protons exchanged in the structure, occurring during electrode preparation, are assumed to disrupt the Na ions extraction mechanism limiting the specific charge of such a material.

Neutron diffraction at 11.4 and 295 K and solid-state (67)Zn NMR are used to determine both the local and the average structures in the disordered, negative thermal expansion (NTE) material, Zn(CN)2. Solid-state NMR not only confirms that there is head-to-tail disorder of the C≡N groups present in the solid, but yields information about the relative abundances of the different Zn(CN)4–n(NC)n tetrahedral species, which do not follow a simple binomial distribution. The Zn(CN)4 and Zn(NC)4 species occur with much lower probabilities than are predicted by binomial theory, supporting the conclusion that they are of higher energy than the other local arrangements. The lowest energy arrangement is Zn(CN)2(NC)2. The use of total neutron diffraction at 11.4 K, with analysis of both the Bragg diffraction and the derived total correlation function, yields the first experimental determination of the individual Zn–N and Zn–C bond lengths as 1.969(2) and 2.030(2) Å, respectively. The very small difference in bond lengths, of ~0.06 Å, means that it is impossible to obtain these bond lengths using Bragg diffraction in isolation. Total neutron diffraction also provides information on both the average and the local atomic displacements responsible for NTE in Zn(CN)2. The principal motions giving rise to NTE are shown to be those in which the carbon and nitrogen atoms within individual Zn–C≡N–Zn linkages are displaced to the same side of the Zn···Zn axis. Displacements of the carbon and nitrogen atoms to opposite sides of the Zn···Zn axis, suggested previously in X-ray studies as being responsible for NTE behavior, in fact make negligible contributions at temperatures up to 295 K.

Binary mixed-metal variants of the one-dimensional MCN compounds (M = Cu, Ag, and Au) have been prepared and characterized using powder X-ray diffraction, vibrational spectroscopy, and total neutron diffraction. A solid solution with the AgCN structure exists in the (Cu(x)Ag(1-x))CN system over the range (0 ≤ x ≤ 1). Line phases with compositions (Cu(1/2)Au(1/2))CN, (Cu(7/12)Au(5/12))CN, (Cu(2/3)Au(1/3))CN, and (Ag(1/2)Au(1/2))CN, all of which have the AuCN structure, are found in the gold-containing systems. Infrared and Raman spectroscopies show that complete ordering of the type [M-C≡N-M'-N≡C-](n) occurs only in (Cu(1/2)Au(1/2))CN and (Ag(1/2)Au(1/2))CN. The sense of the cyanide bonding was determined by total neutron diffraction to be [Ag-NC-Au-CN-](n) in (Ag(1/2)Au(1/2))CN and [Cu-NC-Au-CN-](n) in (Cu(1/2)Au(1/2))CN. In contrast, in (Cu(0.50)Ag(0.50))CN, metal ordering is incomplete, and strict alternation of metals does not occur. However, there is a distinct preference (85%) for the N end of the cyanide ligand to be bonded to copper and for Ag-CN-Cu links to predominate. Contrary to expectation, aurophilic bonding does not appear to be the controlling factor which leads to (Cu(1/2)Au(1/2))CN and (Ag(1/2)Au(1/2))CN adopting the AuCN structure. The diffuse reflectance, photoluminescence, and 1-D negative thermal expansion (NTE) behaviors of all three systems are reported and compared with those of the parent cyanide compounds. The photophysical properties are strongly influenced both by the composition of the individual chains and by how such chains pack together. The NTE behavior is also controlled by structure type: the gold-containing mixed-metal cyanides with the AuCN structure show the smallest contraction along the chain length on heating.

Zn (CN)${}_{2}$ and Ni(CN)${}_{2}$ are known for exhibiting anomalous thermal expansion over a wide temperature range. The volume thermal expansion coefficient for the cubic, three-dimensionally connected material, Zn(CN)${}_{2}$, is negative (${\ensuremath{\alpha}}_{V}=\ensuremath{-}51\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6} {\mathrm{K}}^{\ensuremath{-}1}$) while for Ni(CN)${}_{2}$, a tetragonal material, the thermal expansion coefficient is negative in the two-dimensionally connected sheets (${\ensuremath{\alpha}}_{a}=\ensuremath{-}7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6} {\mathrm{K}}^{\ensuremath{-}1}$), but the overall thermal expansion coefficient is positive (${\ensuremath{\alpha}}_{V}=48\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6} {\mathrm{K}}^{\ensuremath{-}1}$). We have measured the temperature dependence of phonon spectra in these compounds and analyzed them using ab initio calculations. The spectra of the two compounds show large differences that cannot be explained by simple mass renormalization of the modes involving Zn (65.38 amu) and Ni (58.69 amu) atoms. This reflects the fact that the structure and bonding are quite different in the two compounds. The calculated pressure dependence of the phonon modes and of the thermal expansion coefficient, $\ensuremath{\alpha}$${}_{V}$, are used to understand the anomalous behavior in these compounds. Our ab initio calculations indicate that phonon modes of energy \ensuremath{\sim} meV are major contributors to negative thermal expansion (NTE) in both compounds. The low-energy modes of \ensuremath{\sim}8 and 13 meV also contribute significantly to the NTE in Zn(CN)${}_{2}$ and Ni(CN)${}_{2}$, respectively. The measured temperature dependence of the phonon spectra has been used to estimate the total anharmonicity of both compounds. For Zn(CN)${}_{2}$, the temperature-dependent measurements (total anharmonicity), along with our previously reported pressure dependence of the phonon spectra (quasiharmonic), is used to separate the explicit temperature effect at constant volume (intrinsic anharmonicity).

The high pressure behavior is investigated for the solid state form of 4-aminobenzophenone, an organic NLO chromophore. An iso-symmetric phase transformation is observed above 1.0 GPa and it is characterized by single crystal and powder X-ray diffraction and rationalized with calculations at the Density Functional Theory level, under periodic boundary conditions. The structural changes of the molecule and the packing are correlated with the second harmonic generation of this species.

Analysis and modeling of X-ray and neutron Bragg and total diffraction data show that the compounds referred to in the literature as "Pd(CN)(2)" and "Pt(CN)(2)" are nanocrystalline materials containing small sheets of vertex-sharing square-planar M(CN)(4) units, layered in a disordered manner with an intersheet separation of ~3.44 Å at 300 K. The small size of the crystallites means that the sheets' edges form a significant fraction of each material. The Pd(CN)(2) nanocrystallites studied using total neutron diffraction are terminated by water and the Pt(CN)(2) nanocrystallites by ammonia, in place of half of the terminal cyanide groups, thus maintaining charge neutrality. The neutron samples contain sheets of approximate dimensions 30 Å × 30 Å. For sheets of the size we describe, our structural models predict compositions of Pd(CN)(2)·xH(2)O and Pt(CN)(2)·yNH(3) (x ≈ y ≈ 0.29). These values are in good agreement with those obtained from total neutron diffraction and thermal analysis, and are also supported by infrared and Raman spectroscopy measurements. It is also possible to prepare related compounds Pd(CN)(2)·pNH(3) and Pt(CN)(2)·qH(2)O, in which the terminating groups are exchanged. Additional samples showing sheet sizes in the range ~10 Å × 10 Å (y ~ 0.67) to ~80 Å × 80 Å (p = q ~ 0.12), as determined by X-ray diffraction, have been prepared. The related mixed-metal phase, Pd(1/2)Pt(1/2)(CN)(2)·qH(2)O (q ~ 0.50), is also nanocrystalline (sheet size ~15 Å × 15 Å). In all cases, the interiors of the sheets are isostructural with those found in Ni(CN)(2). Removal of the final traces of water or ammonia by heating results in decomposition of the compounds to Pd and Pt metal, or in the case of the mixed-metal cyanide, the alloy, Pd(1/2)Pt(1/2), making it impossible to prepare the simple cyanides, Pd(CN)(2), Pt(CN)(2), or Pd(1/2)Pt(1/2)(CN)(2), by this method.

Two patients presented with the cardinal symptoms of Parkinson's disease (PD), which had developed slowly and progressively. One patient underwent brain imaging of the dopaminergic system, the results of which were compatible with PD. However, both patients showed no response to L-dopa or oral dopaminergic medication. They also had optic nerve atrophy of unknown etiology. The severe motor symptoms of both patients were conspicuously alleviated by apomorphine delivered subcutaneously. One patient underwent bilateral subthalamic nucleus deep brain stimulation, which also proved effective.

The binary cyanide, Cu(CN)2, has never been synthesised. However, by using Ni(CN)42-as a structural synthon, copper(II) can be stabilised in a cyanide-only environment in CuNi(CN)4and in the solid-solution CuxNi1+x(CN)2(0 ≤ x < 1/4). The atomic structure of the layers in CuNi(CN)4and the stacking relationship between nearest-neighbour layers have been determined from total neutron diffraction studies at 10 and 300 K. The structure consists of flat layers of square-planar, ordered [Ni(CN)4] and [Cu(NC)4] units. (NB it is very unusual to find Cu(II) in a genuine square-planar environment within an extended solid). The layered structure of this new material is closely related to those of the Group 10 cyanides, Ni(CN)2, Pd(CN)2.xNH3and Pt(CN)2.xH2O, except that these are generated from vertex-sharing square-planar metal-cyanide units with head-to-tail disorder of the C≡N groups. The overall appearance of the powder X-ray diffraction pattern of CuNi(CN)4, including the unusual peak shapes of the observed Bragg reflections, has been successfully explained using models incorporating stacking disorder between next nearest neighbour layers. CuNi(CN)4forms less extended sheets than Ni(CN)2[1, 2], but larger sheets than those found in Pd(CN)2.xNH3and Pt(CN)2.xH2O, which are nanocrystalline [3]. CuNi(CN)4, like Ni(CN)2[1], shows interesting thermal expansion behavior i.e. intralayer negative thermal expansion (αa = -9.7 MK-1) and interlayer positive thermal expansion (αc = +89 MK-1). CuNi(CN)4forms as an anhydrous material from aqueous solution, unlike Ni(CN)2, which can form hydrates such as Ni(CN)2.nH2O (n = 3, 3/2, 2, 1). However, on investigating the Cu-Ni-CN phase diagram, it is found that nickel-rich compounds, CuxNi1+x(CN)2(0 ≤ x < 1/4), can be formed via hydrated phases, CuxNi1+x(CN)2.3H2O, and readily rehydrate. Attempts to form copper-rich phases results in partial reduction of Cu(II) with the formation of copper(I) cyanide, CuCN, in addition to CuNi(CN)4, suggesting that Cu(II) ions are stable in a cyanide environment only when connected to the nitrogen ends of bridging C≡N ligands. Hence the non existence of Cu(CN)2can now be explained.