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Abstract: A solid solution of magnesium and manganese borohydrides was studied by in situ synchrotron radiation X-ray powder diffraction and infrared spectroscopy. A combination of thermogravimetry, mass and infrared spectroscopy, and atomic emission spectroscopy were applied to clarify the thermal gas desorption of pure Mn(BH4)2 and a solid solution of composition Mg0.5Mn0.5(BH4)2. Mg x Mn(1− x )(BH4)2 (x= 0–0.8) conserves the trigonal structure of Mn(BH4)2 at room temperature. Manganese is dissolved in the hexagonal structure of α-Mg(BH4)2, with the upper solubility limit not exceeding 10mol.% at room temperature. There exists a two-phase region of trigonal and hexagonal borohydrides within the compositional range x =0.8–0.9 at room temperature. Infrared spectra show splitting of various vibrational modes, indicating the presence of two cations in the trigonal Mg x Mn(1− x )(BH4)2 solid solutions, as well as the appearance of a second phase, hexagonal α-Mg(BH4)2, at higher magnesium contents. All vibrational frequencies are shifted to higher values with increasing magnesium content. The decomposition temperature of the trigonal Mg x Mn(1− x )(BH4)2 (x= 0–0.8) does not vary significantly as a function of the magnesium content (433–453K). The desorbed gas contains mostly hydrogen and 3–7.5mol.% diborane B2H6, as determined from analyses of the Mn(BH4)2 and Mg0.5Mn0.5(BH4)2 samples. An eutectic relation between α-Mg(BH4)2 and LiBH4 is observed. The solid solution Mg x Mn(1− x )(BH4)2 is a promising material for hydrogen storage as it decomposes at a similar temperature to Mn(BH4)2, i.e. at a much lower temperature than pure Mg(BH4)2 without significantly losing hydrogen weight capacity thanks to substitution of Mn by Mg up to 80mol.%. The questions of diborane release and reversibility remain to be addressed. [Copyright &y& Elsevier]

Abstract: The crystal structure of YCu6.576, a hyperstoichiometric substitution variant of the CaCu5-structure type, was shown to contain Cu2 dumbbells replacing Y-atoms in a fraction s =0.19 in the formula Y1−s Cu5+2s . The structure type TbCu7 is assigned to the disordered structure (P6/mmm, a =4.96Å, c =4.15Å). The local order in the vicinity of the Cu2-dumbbells has been derived from total scattering X-ray synchrotron data via refinement of the atomic pair distribution function (PDF). The coordinating Cu6-hexagon around the dumbbell site shows a shrinkage of 0.33(1)Å w.r.t. the equivalent environment of the Y-atom. No adjacent Y-atoms are substituted but a hexagonal arrangement of Cu2-dumbbells, separated at least by the vectors √3a and √3b exists in layers perpendicular to c. The stacking along [001] is random and can be modeled locally from the PDF data consistent with both ab- and abc-type stacking. Therefore, the local order is comparable to that in Ni17Th2- and Th2Zn17-structure types. X-ray single crystal analysis and Rietveld refinements of neutron- and X-ray powder data (Bragg diffraction data) of YCu6.576 are consistent with the findings from local crystallography (total scattering data) answering a long-standing question in disordered CaCu5-type based intermetallic structure variants. [Copyright &y& Elsevier]

Abstract: The crystal structure identification of a new Mo–Ni–Re phase was carried out. The chemical characterisation of the studied composition was performed with the help of electron probe microanalysis (EPMA) whereas X-ray diffraction (XRD) and single crystal diffraction techniques were used for structural characterisation. The characterisation results revealed that this new Mo–Ni–Re phase has a modulated σ phase structure. [Copyright &y& Elsevier]

Osteoarthritis (OA), the most common form of arthritis, is characterized by chronic inflammation, degeneration of articular cartilage and whole joints. Local delivery by intra-articular (IA) injection of small molecules is an established treatment to relieve pain and improve joint motion, requiring month-lasting release of therapeutic drug doses. We incorporated anti-inflammatory drug celecoxib in poly (D, L-lactic acid) microparticles using two spray-drying approaches - either as a solid drug solution or embedded as milled nano drug. Differential scanning calorimetry, X-ray powder diffraction, electron microscopy and in vitro drug release allowed comparison of the microparticles. Both types resulted in spherical particles ranging from 20 to 40 μm mean size, with high drug loadings (10% to 50% w/w) and entrapment efficiencies > 80%. However, after 90 days, in vitro celecoxib release from nano drug embedded microparticles presented a significantly slower release in comparison to drug in solution microparticles, attributed to the presence of stabilized amorphous drug. No cytotoxicity was observed in human articular synoviocytes and PGE 2 release was fully suppressed at low doses of both microparticulate systems. This study provides techniques to release high drug loads over months in a tunable manner, providing valuable options for the IA management of osteoarthritis. [ABSTRACT FROM AUTHOR]

Abstract Magnesium and 3 d transition metals closo -dodecaborates were prepared by mechanosynthesis (ball milling) of the mixtures Na 2 B 12 H 12 + MCl 2 (M = Ti, Cr, Mn, Fe, Co, Cu, Zn, Mg) and CuCl, followed by hydration and drying under dynamic vacuum. The crystal structures of hydrated and anhydrous closo -dodecaborates have been characterized by temperature dependent synchrotron radiation X-ray powder diffraction, ab initio calculations, thermal analysis and infrared spectroscopy. Three different complexes containing water were found: a homoleptic octahedral complex in M(H 2 O) 6 B 12 H 12 crystallizing in three different deformation variants of the complex centred closo -dodecaborate cube, a heteroleptic octahedral complex in M(H 2 O) 4 B 12 H 12 containing four water molecules and two hydrogens from a closo -dodecaborate centring also a deformed closo -dodecaborate cube, and a heteroleptic octahedral complex in Fe(H 2 O) 2 B 12 H 12 containing two water molecules where four hydrogen atoms are bridging two closo -dodecaborates. Anhydrous cobalt(II) and copper(I) closo -dodecaborates were obtained by drying the hydrated sample under dynamic vacuum. Both compounds crystallize with bcc packing of closo -dodecaborates where the metal is in octahedral coordination by hydrogen H 6 for cobalt, and a tetrahedral coordination H 4 is found for copper, bridging two closo -dodecaborates in an infinite chain. The orbital overlap between transition metal and closo -anion leads to directional covalent bonding. While CoB 12 H 12 has trigonal symmetry (R 3) allowing for an ordered metal position, Cu 2 B 12 H 12 follows the cubic symmetry of bcc packing, which leads to a disordered metal position. The structure of NiB 12 H 12 , originally published as monoclinic (I 2), is revised based on the trigonal structural model of CoB 12 H 12. Graphical abstract Image 1 Highlights • Milling of Na 2 B 12 H 12 +metal chloride + hydration = hydrated metal closo -borate. • The water molecules are easily removed by heating under dynamic vacuum. • Anhydrous CoB 12 H 12 , NiB 12 H 12 and Cu 2 B 12 H 12 are stable at ambient conditions. [ABSTRACT FROM AUTHOR]

Sodium chromium oxide, NaCrO 2 , has received significant attention as positive electrode (cathode) for Na-ion batteries mainly due the high capacity retention of the material. In this paper, we use operando powder X-ray diffraction to investigate the structural evolution of O3–NaCrO 2 during Na-ion extraction and insertion with use of both liquid and solid-state electrolytes. This reveals a previously overlooked phase transition, causing formation of an unexplored O′3-Na x CrO 2 intermediate during Na-ion extraction (charge). The phase transitions within the electrode are investigated by sequential Rietveld refinement and distortion analysis, which shows that the discovered O′3-Na x CrO 2 intermediate accommodates the increasing interlayer repulsion and in-plane contraction with less distortion of the [NaO 6 ]-polyhedra as compared to the other observed phases. Our structural findings are corroborated by analysis of the Na-ion diffusion coefficients through the galvanostatic intermittent titration technique. Furthermore, the operando powder X-ray diffraction reveals substantial charge-discharge asymmetry with a significant preference for solid-solution and two-phase behavior during charge (Na-extraction) and discharge (Na-insertion), respectively. [Display omitted] • A new intermediate is observed during charge of NaCrO 2 cathodes. • Severe charge-discharge asymmetry is observed in the phase evolution for NaxCrO2. • The asymmetry appears to originate from differences in Na-diffusion coefficients. [ABSTRACT FROM AUTHOR]