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Energy-dispersive X-ray diffraction (EDXRD) is extremely insensitive to sample morphology when implemented in a back-reflection geometry. The capabilities of this non-invasive technique for cultural heritage applications have been explored at high resolution at the Diamond Light Source synchrotron. The results of the XRD analysis of the pigments in 40 paints, commonly used by 20th century artists, are reported here. It was found that synthetic organic pigments yielded weak diffraction patterns at best, and it was not possible to unambiguously identify any of these pigments. In contrast, the majority of the paints containing inorganic pigments yielded good diffraction patterns amenable to crystallographic analysis. The high resolution of the technique enables the extraction of a range of detailed information: phase identification (including solid solutions), highly accurate unit cell parameters, phase quantification, crystallite size and strain parameters and preferred orientation parameters. The implications of these results for application to real paintings are discussed, along with the possibility to transfer the technique away from the synchrotron and into the laboratory and museum through the use of state-of-the-art microcalorimeter detectors. The results presented demonstrate the exciting potential of the technique for art history and authentication studies, based on the non-invasive acquisition of very high quality crystallographic data., Comment: Main article: 25 pages, 5 figures; Supplementary information: 35 pages, 37 figures. Accepted for publication in the Journal of Cultural Heritage with revisions

The products of the solid-state reactions between potassium metal and tetracene (K:Tetracene, 1:1, 1.5:1, and 2:1) are fully structurally characterized. Synchrotron X-ray powder diffraction shows that only K2Tetracene forms under the reaction conditions studied, with unreacted tetracene always present for x < 2. Diffraction and 13C MAS NMR show that K2Tetracene has a crystal structure that is analogous to that of K2Pentacene, but with the cations ordered on two sites because of the influence of the length of the hydrocarbon on possible cation positions. K2Tetracene is a nonmagnetic insulator, thus further questioning the nature of reported superconductivity in this class of materials., Potassium intercalated tetracene, K2Tetracene, is synthesized and its crystal structure solved and refined from powder data. The crystal chemistry of the K2Tetracene phase contrasts clearly with that of the other alkali metal intercalated polyaromatic hydrocarbons structures reported to date in a way that can be directly related to the molecular structure of tetracene in that the cations cannot be disordered due to fewer sites present in the structure compared to other PAHs studied.

Hydrothermal crystallisation of CeO2 from aqueous sodium hydroxide solution at 240oC using CeCl3·7H2O in the presence of hydrogen peroxide with addition of either SbCl3 or SbCl5 yields polycrystalline samples of antimony-containing ceria directly from solution. Powder X-ray diffraction shows a contraction of the cubic lattice parameter with increasing Sb content, and also a broadening of Bragg peaks, from which Scherrer analysis yields crystallite domain sizes of 5 - 20 nm. Scanning transmission electron microscopy provides consistent results with observation of highly crystalline particles of a few nm in diameter. X-ray absorption near edge structure spectroscopy at the Ce LIII and Sb K edges reveals the presence of Ce4+ and Sb5+ in the solids. To balance charge the presence of co-included Na is proposed, corroborated by elemental analysis. The general chemical formula of the materials can thus be written as (Ce1 xSbx)1 yNayO2-δ (where x < 0.4 and y ≥ x/3). Sb K-edge extended X-ray absorption fine structure spectroscopy of the substituted ceria samples shows that the local structure of Sb resembles that in NaSbO3, where six-coordinate metal sites are found, but with evidence of a longer interatomic correlation due to surrounding Ce/Sb atoms in the fluorite structure; this implies that the Sb is displaced from the ideal eight-coordinate site of the fluorite structure. This structural distortion gives materials that are unstable under reducing conditions, coupled by the ease of reduction to elemental antimony, which is extruded leading to phase separation.

6,6′,13,13′- tetrahydro-6,6′-bipentacene (HBP), the first intermediate molecule between pentacene and peripentacene and extended pentacene oligomers, is synthesised and crystallographically characterised for the first time. Heating pentacene to 300 oC under vacuum for 200 hours results in pale golden crystals of HBP and amorphous material containing pentacene oligomers, and is the first experimental evidence that pentacene preferentially dimerises at the 6,6′- position. Continued heating of HBP results in co-crystals of 6,13-dihydrogenated pentacene (HP) and pentacene and further amorphous pentacene oligomers. The amorphous material consists of layered carbonaceous species with a graphenic nature, as determined by Raman spectroscopy and electron microscopy, and shows the importance of HBP as an intermediate to hydrogenated pentacene species and pentacene oligomers. The synthesis of HBP from pentacene could be useful as a starting material in the rational synthesis of peripentacene towards organic electronic devices.

We present the synthesis and characterization of the K

Hydrothermal crystallisation of CeO2 from aqueous sodium hydroxide solution at 240 °C using CeCl3·7H2O in the presence of hydrogen peroxide with addition of either SbCl3 or SbCl5 yields polycrystalline samples of antimony-containing ceria directly from solution. Powder X-ray diffraction shows a contraction of the cubic lattice parameter with increasing Sb content, and also a broadening of Bragg peaks, from which Scherrer analysis yields crystallite domain sizes of 5-20 nm. Scanning transmission electron microscopy provides consistent results with observation of highly crystalline particles of a few nm in diameter. X-ray absorption near edge structure spectroscopy at the Ce LIII- and Sb K-edges reveals the presence of Ce4+ and Sb5+ in the solids. To balance charge the presence of co-included Na is proposed, corroborated by elemental analysis. The general chemical formula of the materials can thus be written as (Ce1-xSbx)1-yNayO2-δ (where x0.4 and y ≥ x/3). Sb K-edge extended X-ray absorption fine structure spectroscopy of the substituted ceria samples shows that the local structure of Sb resembles that in NaSbO3, where six-coordinate metal sites are found, but with evidence of a longer interatomic correlation due to surrounding Ce/Sb atoms in the fluorite structure; this implies that the Sb is displaced from the ideal eight-coordinate site of the fluorite structure. This structural distortion gives materials that are unstable under reducing conditions, coupled by the ease of reduction to elemental antimony, which is extruded leading to phase separation.

We provide an overview of currently emerging areas in the solvothermal synthesis of polycrystalline oxide materials that illustrate how tailoring synthesis may be possible to target the formation of functional solids. We illustrate various levels of control in preparation of functional oxides with interesting structures and compositions by choosing examples of three aspects of recent chemistry: (1) materials discovery, (2) substitutional chemistry and (3) adjustment of crystal morphology and size. This includes new oxides of ruthenium, iridium and of bismuth, novel substitutional chemistry of CeO2 and TiO2, and control of crystal form of binary and ternary oxides. The accumulated research illustrates the potential for fine control of the properties of materials by targeted crystallisation of solid oxides with selected chemical composition and particle shape and dimensions from the nanoscale to the micronscale. These benefits uniquely arise from chemical variation possible by use of solution-mediated crystallisation. We conclude by discussing how future work must focus on developing predictive synthesis, where synthesis conditions could be selected to design a solid material with desired properties.

A new barium ruthenium oxyhydroxide Ba4Ru3O10.2(OH)1.8 crystallises under hydrothermal conditions at 200 °C: powder neutron diffraction data show it adopts an 8H hexagonal perovskite structure with a new stacking sequence, while high resolution electron microscopy reveals regions of ordered layers of vacant Ru sites, and magnetometry shows antiferromagnetism with TN = 200(5) K.

Partial substitution of Ce

The pyrochlore solid solution (Na0.33Ce0.67)(2)-(Ir1-xRux)(2)O-7 (0

Alkali metal intercalation into polyaromatic hydrocarbons (PAHs) has been studied intensely after reports of superconductivity in a number of potassium- and rubidium-intercalated materials. There are, however, no reported crystal structures to inform our understanding of the chemistry and physics because of the complex reactivity of PAHs with strong reducing agents at high temperature. Here we present the synthesis of crystalline K2Pentacene and K2Picene by a solid–solid insertion protocol that uses potassium hydride as a redox-controlled reducing agent to access the PAH dianions, and so enables the determination of their crystal structures. In both cases, the inserted cations expand the parent herringbone packings by reorienting the molecular anions to create multiple potassium sites within initially dense molecular layers, and thus interact with the PAH anion π systems. The synthetic and crystal chemistry of alkali metal intercalation into PAHs differs from that into fullerenes and graphite, in which the cation sites are pre-defined by the host structure.

Ba4Ru3O10.2(OH)1.8 is prepared under hydrothermal conditions from a 2:1 molar mixture of BaO2 and KRuO4 in H2O (autoclave, 200 °C, 1 d).

We report an experimental and computational study of the magnetic and electronic properties of the layered Ru(V) oxide $\mathrm{SrR}{\mathrm{u}}_{2}{\mathrm{O}}_{6}$ (hexagonal, $P\overline{3}1m)$, which shows antiferromagnetic order with a N\'eel temperature of 563(2) K, among the highest for $4d$ oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers. Electrical transport measurements using focused-ion-beam--induced deposited contacts on a micron-scale crystallite as a function of temperature show $p$-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure, and Monte Carlo simulations reveal how strong intralayer as well as weaker interlayer interactions are a defining feature of the high-temperature magnetic order in the material.

The direct hydrothermal crystallisation at 240 °C of Pd2+-containing ceria is investigated to study the extent to which precious metal dopants may be introduced into the cubic fluorite lattice. Samples of composition Ce1−xPdxO2−δ, where 0 ≤ x ≤ 0.15 can be produced in which Pd is included within the CeO2 structure to give a linear lattice expansion. Attempts to produce higher Pd2+-substitution result in the formation of PdO as a secondary phase. Ce and Pd were determined to be in the +4 and +2 oxidation states, respectively, by X-ray absorption near edge structure, suggesting oxide deficiency as the mechanism of charge balance. Extended X-ray absorption fine structure (EXAFS) analysis at the Pd K-edge reveals that Pd2+ has local square-planar coordination, as expected, and that a structural model can fitted in which the average fluorite structure is maintained, but with Pd2+ sitting in the square faces of oxide ions present in the local cubic geometry of Ce. This model, consistent with previous modelling studies, gives an excellent fit to the EXAFS spectra, and explains the observed lattice expansion. Transmission electron microscopy analysis shows that Pd is well dispersed in the nanocrystalline ceria particles, and in situ powder XRD shows that upon heating in air the samples remain stable up to 800 °C. H2-TPR shows that Pd-substitution leads to low temperature (

Ca1.5Ru2O7 (I), SrRu2O6 (II), and Ba2Ru3O9(OH) (III) are hydrothermally synthesized from aqueous mixtures of KRuO4 and MO2 (M: Ca, Sr, Ba; autoclave, 200 °C, 24 h).