bluuebunny/crossref_metadata_2025 huggingface dataset:
Teaching Crystallography in Latin America
Authors: Díaz de Delgado Graciela
Published: November 2015

Crystallography in Latin American seems to have started in the mid 1930s after the pioneering work of Ernesto Galloni, in Argentina. Since then, Crystallography was associated with undergraduate research and conducted in Departments or Institutes of Physics and Chemistry and later in Molecular Biology and Materials Science Departments. Most undergraduate degree programs required carrying out a research project for one or two semesters, writing a thesis, and making a public presentation of the work before a committee. Even after graduate degree programs started and began to consolidate, undergraduate degree research in Crystallography maintains its importance. The expertise and dedication of many Latin American crystallographers, most of whom graduated or visited important academic institutions in Europe and the US, created the foundations of our discipline in the region. For instance, after a work visit paid to Prof. B.E. Warren (MIT), Dr. Carlos Graef Fernández organized and taught the landmark course "Rayos X y Física Cristalográfica", at UNAM (Mexico) in 1947. Since then, the efforts of distinguished crystallographers, such as Galloni, Cano Corona, Fabregat Guinchard, Witke, Caticha-Ellis, Becka, Mascarehnas, among others, with support from UNESCO, IUCr, TWAS, and other institutions, helped to establish the tradition of teaching crystallography. In numerous courses, Ewald, Buerger, Hauptman, Karle, Woolfson and other prominent crystallographers participated as instructors. Many crystallographers helped to establish laboratories outside their countries of origin. In 1967, Amzel, Becka, and Baggio, worked at UCV, in Caracas, Venezuela, supervising undergraduate degree thesis based on crystallographic work. Later, Eldrys de Gil, after graduation from UCV, founded the Crystallography Laboratory of ULA (Mérida, Venezuela) which this year celebrates its 45 anniversary. An overview of key recent educational events and modern practices in Latin America will be presented.
Crystal structure of unusual RNA duplex containing strontium ion binding motif
Authors: Kanazawa Hiroki , Kondo Jiro
Published: November 2015

Crystal structures of several functional non-coding RNAs, such as ribozymes, aptamers, ribosomes and tRNAs, have been reported so far. Unusual structural motifs and non-complementary base pairs are important for their functions. In the present study, we have determined a crystal structure of an unusual RNA duplex containing a strontium ion binding motif. A 19 mer RNA (5'-UUGUCGCUU[Br]CGAAAAAGUC-3') was chemical synthesized and purified by denaturing PAGE. Crystallizations were performed by the sitting-drop vapor diffusion method. The initial phase was solved by the SAD method. Atomic parameters were refined at a resolution of 3.0 Å. The 19 mer RNA forms an unusual antiparallel duplex. At both ends of the duplex, the Watson-Crick G=C and A-U and the Wobble GoU and AoC base pairs are formed. The Wobble C10oA14* pair is available only in acidic condition by protonation of N1 of A14* (* indicates residues of the opposite strand). Two hydrogen bonds, N1-H(A14*)...O2(C10) and N6-H(A14*)...N3(C10), are observed in the base pair. In the center of the duplex, two sheared G11oA13* and G11*oA13 base pairs are formed. The distance between two RNA chains becomes shorter by the GoA base pair and hydrogen bonds between the Watson-Crick edge of G11 and the phosphate group of A12*. Therefore, the central A12 residue cannot make a base pair, but it makes a stacking interaction with A12*. The A12 residue stacks also with A13 of the sheared GoA base pair. As a result, an A13-A12-A12*-A13* stacked column is formed at the minor groove of the duplex, and the G11 base of the sheared GoA base pair is inclined toward the minor groove. By taking such a unique structure, the RNA duplex has a Sr2+ ion binding pocket in the center. A hydrated Sr2+ ion binds to O6 and N7 of G11 and G11*. The Sr2+ ion is surrounded by four phosphate groups of two RNA chains. The Sr2+ ion is tightly captured by eight hydrogen bonds in total.
Applications of Coordination Chemistry in Biological Systems
Authors: Kaur Gurpreet , Hartshorn Richard
Published: November 2015

A novel 2,2′:6′,2″-terpyridine–picolylamine-based bridging ligand has been synthesized and fully characterized using a variety of analysis techniques including single crystal X-ray diffraction. As shown in figure (a), the ligand has both tridentate and bidentate metal binding sites available to coordinate with various metal ions. By varying the size of anions both dinuclear complexes and supramolecular assemblies have been produced. Addition of metal salts containing small anions like halides result in formation of Cu2L and Zn2L dinuclear complexes, figure (b), where one metal ion binds at each of the binding sites of the ligand. The metal ions in these complexes mimic active site of the hydrolytic enzymes and promote phosphatediester hydrolysis of model DNA/RNA compounds. Nearly ten times increase in the rate of hydrolysis of bis(p-nitrophenyl)phosphate (BNPP) is observed in comparison to the parent terpyridine and picolylamine complexes under physiological conditions. Larger anions like PF6-, ClO4-, SO42- , NO3- result in formation of Zn4L4 type squares via. head-to-head and tail-to-tail, HH-TT, (H=tridentate site, T=bidentate site) coordination of the ligand. The octahedrally bound Zn(II) ion between two tridentate sites can be replaced with Fe(II) to prepare Fe2Zn2L4 squares. A flat molecule of terephthalic acid was also deliberately encapsulated in the middle of the Fe2Zn2L4 square as shown in figure (c). The head-to-tail, HT, coordination of the ligand in case of Ni(II) results in formation of decanickel wheels, like [Ni10L10Cl4(H2O)6](Cl)15Br·~140H2O shown in figure (d). Due to the large structure of the molecule X-ray crystallographic studies rather have been quite challenging.
Investigation of orbital disorder in Ca-doped LaMNO3
Authors: Thygesen Peter , Goodwinn Andrew
Published: November 2015

Studies of materials that exhibit colossal magnetoresistance (CMR) have been well documented over the past decade [1]. La1-xCaxMnO3 is one such CMR material that has attracted significant attention as it is relatively cheap and straightforward to synthesize. CMR materials have potential use among the next generation of magnetic memory devices, magnetic-field sensors, and transitors. For that to be possible a clear understanding has to be determined for the origin of the CMR phenomenon. Recent studies of CMR manganites have shown that a `polaron glass' phase precedes CMR behaviour at high temperatures (figure 1) [2]. This glasslike state sits midway between the high-temperature polaron liquid and the fully orbital-ordered solid with polarons. The polarons are localized charge density fluctuations associated with lattice deformation which gives rise to static, short-range correlations. At low temperature these polaron correlations are thought to evolve into the nanoscale polarons responsible for CMR itself. This poster describes our reasoning for the anticipated connection between the orbital disorder and CMR in La1-xCaxMnO3 revealed via reverse Monte Carlo modelling of X-ray and neutron total scattering data.
Site-specific RXMS study on the magnetic electron of magnetite
Authors: Okube Maki , Sasaki Satoshi
Published: November 2015

Magnetite Fe3O4 is the best known magnetic mineral for its attractive properties for various magnetic applications. The magnetic moments of Fe atoms show a collinear ferrimagnetic ordering between tetrahedral A and octahedral B sites in an inverse spinel structure with the chemical formula of [Fe3+]A[Fe2+Fe3+]BO4. The distribution of the Fe2+ and Fe3+ over A and B sites is determined by a delicate balance of the crystal field. The geometrical environment of 3d transition metals strongly affects the distribution and the energy state of magnetic electrons which contributes magnetic moments. The resonant x-ray magnetic scattering (RXMS) allows us to make site-selective structural analysis with respect to the magnetic electron. In order to clarify the behavior of the magnetic electrons in magnetite, we carried out the energy-dependent RXMS near Fe K edge. Depends on the observation related to 3d-4p electric transition to empty bands of unpaired electron, we studied the orbital interaction and the density of state of magnetic electrons in A site and B site of magnetite independently. RXMS intensity measurements were performed by using Rigaku AFC-5u four-circle diffractometers at BL-6C of Photon Factory. Circularly-polarized X-rays were produced by a transmitted-type phase retarder of diamond (111). According to the X-ray magnetic circular dichroism (XMCD) spectrum at the Fe K edge, 48 x-ray energies to perform RXMS measurement were selected. The magnetic form factors for various energies were calculated from the difference in diffraction intensities between left- and right-circular polarized measurements. By examining the energy dependence of the resonant magnetic peaks, the density of state of 3d magnetic electron of Fe were obtained for A and B site through the experimental analysis. In the presentation, the interrelationship between the site geometry and the magnetic electrons in terms of energy state will be discussed.
Long-range ordered magnetic structures in Li2MnSiO4and Li2CoSiO4
Authors: Mohamed Zakiah , Avdeev Maxim , Ling Chris
Published: November 2015

The lithium orthosilicates Li2MnSiO4 and Li2CoSiO4 have been synthesized by solid state reaction and characterized using X-ray powder diffraction (XRD), magnetic susceptibility measurement, heat capacity and neutron powder diffraction (NPD). The monoclinic Li2MnSiO4 and orthorhombic Li2CoSiO4 compound were found to be antiferromagnetically ordered below Neel temperature = ~12 K and ~13 K respectively. The ordered magnetic structures of both compounds have been solved for the first time using low temperature neutron diffraction data. The magnetic structure of Li2CoSiO4 can be described as antiferromagnetic quasi-layers stacked along the a-axis. The ordered magnetic moments of the Co2+ and Mn2+ are aligned perpendicularly and obliquely to the distorted closed-packed layers of oxygen atoms and the values, 2.9 bohr magneton and 4.6 Bohr magneton, are close to the expected values for d7 Co2+ and d5 Mn2+, respectively. The origin of these complex magnetic structures will be discussed in terms of super-superexchange interactions among the transition metal ions, mediated by bridging SiO4 tetrahedra. Figure 1: Magnetic sublattices in Li2CoSiO4 (left) and Li2MnSiO4 (right) with respect to crystal structure. Blue, yellow, and light and dark green show the M, Si, and Li1 and Li2 sites in Pbn21 Li2CoSiO4 and P21/n Li2MnSiO4.
Substitution effect in high-Tc mercury-based cuprate superconductor
Authors: Matsumura Ryutaro , Okube Maki , Sasaki Satoshi
Published: November 2015

HgBa2Ca2Cu3O8+δ superconductor (Hg-1223) still has the highest critical temperature in various superconductors, which is a layered perovskite with the space group of P4/mmm. A structural unit of cation-layers is stacked in a sequence of -HgO-BaO-CuO-Ca- along the c-axis. The substitution of Hg by Pb enhances the stability of the Hg-1223 phase because the high steam pressure of Hg lowers the chemical stability in synthesis. However, the doping into Hg layers is related to an interstitial oxygen defect. On the other hand, the substitution of Ba by Sr improves the hole doping of CuO2 planes. Thus, the element substitution in Hg and Ba sites becomes a key factor in synthesizing high-quality superconductors. Therefore, the cation distribution in the two sites has been examined by the two-wavelengths anomalous dispersion (TWAD) method of synchrotron X-ray resonant scattering. Single crystals of Hg-1223 were grown at T = 1130 K by the liquid-assisted solid-state recrystallization method from the precursor powder prepared by spray drying or evaporation of the nitrate solutions. Oxygen contents in the precursors were determined by iodometric titrations. Four samples of Hg0.45Pb0.30Ba1.63Sr0.50Ca1.94Cu3O8 (Tc = 128 K), Hg0.42Pb0.41Ba1.19Sr1.06Ca1.97Cu3O8 (125 K), Hg0.50Pb0.50Ba0.59Sr1.24Ca1.83Cu3.34O8 (116 K) and Hg0.34Pb0.54Ba0.61Sr1.17Ca1.88Cu3O8 (115 K) were selected for single-crystal intensity measurements. A conventional measurement to determine the Ba-site occupancy was made to use a Rigaku AFC-5 four-circle diffractometer with Mo Kα radiation. After the absorption correction by the arbitrary-shape grid-integration method, crystal-structure refinements were successfully performed with R factors ranging 6.4 to 6.7 %. The site preference of Hg, Pb and Cu in the Hg site was determined with a vertical-type four-circle diffractometer in PF-BL-10A, where wavelengths of λ = 1.3906 and 1.0191 Å were used at Cu K and Hg LIII absorption edges, respectively. In the TWAD method with least-squares calculations, a variation of the residual factors gives a minimum against the contents of Hg or Cu, suggesting, for example, that Cu does not occupy the Hg site for all samples. In the presentation the site preference and structural change will be discussed in the aspects of superconductivity.
BH4 cluster ordering in complex metal borohydrides
Authors: Kupczak Arkadiusz , Pytlik Lucjan
Published: November 2015

Complex borohydride compounds attract an increasing interest as hydrogen storage materials. Although they have been investigated for more than fifty years, there is still a lot of unknown physical phenomena awaiting to be revealed regarding, for example the dynamics and ordering of BH4 clusters in different borohydrides. The orientation of BH4 unit with respect to the surrounding metallic atoms is unique for a particular metal and determines e.g. the crystal space group, total energy of a system and the potential freedom of BH4 movement, like rotations, within the crystal structure. The information about rotations is of great importance for understanding how the hydrogen atoms behave in such systems [1,2]. To gain a closer look on how the borohydride clusters can rotate, their geometrical arrangement has been studied using analysis of tensor of inertia (TI). Free BH4 takes the form of a regular tetrahedron, but when it is placed among metal atoms, a compound is formed, in which certain deformation of this tetrahedral atomic arrangement may take place. Here the TI analysis turns out to be an efficient tool, since it might reveal how the BH4 deformation influences its rotational freedom, by analyzing the principal moments of inertia and principal eigenvectors corresponding to them, which are in fact, the most probable rotation axes. In the paper a comprehensive study is presented and the possible axes of rotation in complex metal borohydrides MBH4 (M=Li, Na, Ca, K, Mn, Rb, Cs, Sr, Zr), are discussed. For a given metal borohydride TI is performed on both experimentally obtained structures and predicted by theoretical calculations. A comparison of these results gives an insight into how the theory reflects real measurements and what discrepancies or similarities are observed.
Mapping domains in the weak ferromagnet CoCO3
Authors: Beutier Guillaume , Collins Steve , Nisbet Gareth , Ovchinnikova Elena , Dmitrienko Vladimir
Published: November 2015

The Dzyaloshinskii-Moriya (DM) interaction [1,2] produces a perpendicular component in the coupling of neighbouring spins when the symmetry between the spins is low, or can drive a distortion of intervening atoms to create a spontaneous electric polarization in some magnetoelectrics. In weak ferromagnets, the canting of the atomic moments due to the DM interaction leads to a small parasitic ferromagnetic polarization in an otherwise antiferromagnetic structure. Recently, we determined the sign of the Dzyaloshinskii–Moriya interaction in the weak ferromagnet FeBO3 by measuring the interference between resonant x-ray scattering and non-resonant magnetic scattering at a forbidden reflection [3]. Using the same method, we determine its sign in the carbonates MnCO3 and CoCO3. These isostructural materials turn out to show opposite interference effect: further analysis is underway to confirm or not that they actually have Dzyaloshinskii–Moriya interactions of opposite signs. We go one step further and apply the same principle to map the absolute orientation (direction and sense) of the magnetisation in a crystal of CoCO3: by mapping the 009 forbidden reflection at 3 azimuthal angles, we obtain 3 projections of the local magnetisation allowing its unambiguous determination. The reconstructed magnetisation map, whose spacial resolution is about 20 µm x 20 µm (the size of the focused x-ray beam), was measured after zero-field cooling to 9 K, well below the Neel temperature. It confirms the strong in-plane anisotropy of the material, with magnetisation domains essentially along 6 orientations separated by 600. Two of them, with orientation at 600to each other (green and orange in the figure), are largely dominant on the part of the sample that was imaged. To our knowledge it is the first experimental determination of the absolute orientation of the magnetic moments in a weak ferromagnet. The figure shows the reconstructed map of magnetisation, with the direction of the local in-plane magnetisation encoded (in radians) on a periodic colour map.
Measuring the sense of the Dzyaloshinskii–Moriya interaction
Authors: Dmitrienko Vladimir , Ovchinnikova Elena , Collins Steve , Nisbet Gareth , Beutier Guillaume , Kvashnin Yaroslav , Mazurenko Vladimir , Lichtenstein Alexander , Katsnelson Mikhail , Rogalev Andrei
Published: November 2015

The spin-orbit Dzyaloshinskii–Moriya (DM) interaction EDM=D·[s1×s2] can induce small canting of neighboring magnetic moments s1 and s2. It is also very important for multiferroics and helimagnetic MnSi-type crystals with the spiral or Skyrmionic structures. The sense of the DM vector D has been experimentally determined for the first time in canted antiferromagnetic FeBO3 crystal [1]. The technique of interference between magnetic and resonant channels in synchrotron x-ray scattering was exploited. The phase of antiferromagnetic ordering (and scattering) was fixed by external magnetic field and the phase of resonant scattering was calculated with FDMNES program. Similar experiments have been also performed for MnCO3 and CoCO3 crystals. For Fe2O3 hematite crystal, the technique of interference between magnetic and multiple diffraction channels has been used. The experimental measurements are supported by ab initio calculations of the DM interaction. The first-principles calculations have been performed with Local Density Approximation incorporating the on-site Coulomb interaction U and the Spin-Orbit coupling (LDA+U+SO) [2,3]. It was found how DM interaction depends on displacements of oxygen atoms. These experimental and theoretical approaches open up new possibilities for exploring, modeling and exploiting novel magnetic and multiferroic materials. VED and ENO are grateful to the RFBR research project No. 13-02-00760 and to the project of Presidium of Russian Academy of Sciences No. 24. The work of VVM is supported by the grant program of President of Russian Federation MK-5565.2013.2, the contracts of the Ministry of education and science of Russia N 14.A18.21.0076 and 14.A18.21.0889. MIK acknowledges a financial support by FOM (The Netherlands).
Multiferroicity from charge ordering? A case study
Authors: Angst Manuel
Published: November 2015

Magnetoelectric multiferroics have a large applications potential. Among possible mechanisms of multiferroicity, ferroelectricity originating from charge ordering (CO) is particularly intriguing because it potentially combines large electric polarizations with strong magnetoelectric couplings – but example materials where this is realized are very difficult to find. I will present a case study of such materials, rare earth ferrites, which were recently found to be a non-example. After LuFe2O4 had been proposed to be a multiferroic due to ferroelectricity originating from Fe2+/Fe3+ CO below 320 K, it has become the generally accepted prototypical example of this mechanism, attracting increasing attention. The proposal had been made due to indications of a polar state by dielectric and pyroelectric measurements, and a reasonable model of CO based on the location of superstructure reflections. This model has not been verified though, and the spin-order has been unknown. I will present x-ray and neutron diffraction, and circular dichroism, measurements that allowed i) a full refinement of the CO crystal structure [1], ii) the determination of the spin structures in two nearly degenerate competing magnetic phases [2], and iii) the relation between these orderings [1]. The results reveal a very strong spin-charge coupling. Most importantly, the unambiguously determined arrangement of Fe2+ and Fe3+ ions excludes any CO-based ferroelectricity – suggesting that LuFe2O4 and other rare earth ferrites are not ferroelectric [3]. Time permitting I will also briefly discuss recent time-resolved diffraction experiments on magnetite, another (more likely) candidate material for CO-based ferroelectricity.
Experimental Charge Density studies of Ge(II) complexes using beamline I19
Authors: Wilson Claire , Coles Simon , Levason William , Reid Gillian , Zhang Wenjian
Published: November 2015

Interest in the p-block elements has recently been stimulated by the need for new reagents for materials and electronics applications, as well as the intrinsic interest in the unprecedented structures and properties observed. For germanium the development of low-valent compounds, organometallics, multiply bonded species, radicals and clusters is of significant importance. We have probed the coordination chemistry of Ge(II) with a range of neutral ligands, few examples of which were reported until recently. They exhibit many striking features including diverse structural motifs and highly variable coordination numbers (between 3 and 8) [1] suggesting the Ge centre does not to have a strong stereochemical preference and small differences in steric and electronic properties of the donor ligands have a significant role. Bonding models have been used to rationalise the observed structures with a Ge-based lone pair occupying the stabilised Ge 4s orbital. However these models are not entirely satisfactory and experimental charge density studies could provide valuable insights into the structures and chemistry of these compounds. [GeCl2(2,2'-bipyridine)], 1, and [GeCl2(1,2-bis(dimethylphosphino)benzene], 2, were selected as targets for initial experimental charge density studies and data have been collected using 3 different experimental configurations of the small molecule single-crystal diffraction beamline I19 [2] at Diamond Light Source. Using a Rigaku Saturn 724+ CCD detector on a 4-circle kappa-geometry CrystalLogic goniometer, data for 1 were collected at λ=0.6889Å without bimorph focussing mirrors in place, and for 2 data were collected at both λ=0.6889Å with bimorph mirrors and λ=0.4859Å without mirrors giving data to 0.48 and 0.38 Å resolution respectively. Details of the analysis of the topology of the electron density will be presented with the insights gained into the bonding in these unusual complexes.
Synchrotron charge density studies of chemical bonding in the polymorphs of FeS2
Authors: Overgaard Jacob , Schmøkel Mette , Bjerg Lasse , Cenedese Simone , Jørgensen Mads , Chen Yu-Sheng , Iversen Bo
Published: November 2015

The experimental charge density (CD) distributions in both polymorphs of the photovoltaic compound iron-disulphide (FeS2; cubic pyrite and orthorhombic marcasite) will be described.[1] The CDs are determined by multipole modelling using synchrotron X-ray diffraction data collected at 10 K on extremely small single crystals (<10 mu) thus minimizing the influence of systematic errors such as absorption, extinction and TDS, and exploiting experiences gained from our recent synchrotron studies of CoSb3.[2] The analysis of the charge density in both polymorphs of FeS2 provides an opportunity to see how the different geometries affect local atomic properties, such as 2-center chemical bonding, atomic charges and d-orbital populations. In particular, the data and the resulting multipole models enable us to link the atomic-centered view that emerges from the multipole analysis with the band structure approach. This is carried out by combination with results from periodic calculations on the compounds in the experimental geometries using WIEN2k, thereby providing unambiguous answers to a number of unsolved issues regarding the nature of the bonding in FeS2. The chemical bonding will be characterized by topological analyses showing that the Fe-S bonds are polar covalent bonds, with only minor charge accumulation but significantly negative energy densities at the bond critical points. Using the IAM as reference, density is found to accumulate in-between the atoms, supporting a partial covalent bonding description. The homopolar covalent S-S interaction is seemingly stronger in pyrite than in marcasite, determined not only from the shorter distance but also from all topological indicators. Integrated atomic (Bader) charges show significantly smaller values than those estimation based on crystal-field theory of Fe2+, S-1. In connection with this, the experimentally derived d-orbital populations on Fe are found to deviate from the commonly assumed full t2g set, empty eg set, and they fit very well with the theoretical individual atomic orbitals projected density of states showing a higher dxy participation in the valence band in marcasite compared with pyrite. Thus, the differences between the two polymorphic compounds are directly reflected in their valence density distributions and d-orbital populations.
The structural relaxation properties of the amorphous ices
Authors: Salzmann Christoph , Shephard Jacob , Evans John
Published: November 2015

Despite the importance of low-density amorphous ice (LDA) in critical cosmological processes and its prominence as one of the polyamorphs of water there is still an incomplete picture of the processes that take place upon thermal annealing. We show that a gradual structural relaxation process takes place upon heating vapor-deposited LDA, also called amorphous solid water, and LDAs obtained from several different states of high-density amorphous ice. The structural relaxation leads to an increase in structural order on local and more extended length scales as the average O-O distance shortens and the O-O distance distribution narrows. The relaxation process is separate from crystallization and it does not seem to reach completion before crystallization sets in. Our findings are therefore difficult to reconcile with the postulated glass transition of LDA to the supercooled and highly viscous liquid prior to crystallization. On the basis of a comparison of the calorimetric data of LDA with those of some of the crystalline phases of ice we propose that the calorimetric feature of LDA prior to crystallization may in fact be connected to the kinetic unfreezing of defect-migration mediated reorientation dynamics. We finally discuss the relaxation properties of the various kinds of high-density amorphous ice in the context of these new findings.
Frustrations in Molecular System under High Pressure
Authors: Abe Hiroshi , Shigemi Machiko , Takekiyo Takahiro , Yoshimura Yukihiro , Hamaya Nozomu
Published: November 2015

Even at ambient pressure, liquid and solid states of room temperature ionic liquids (RTILs) are quite complicated because of a variety of charge network (scalar), molecular orientational order (vector) and coordination number (topology) based on degrees of freedom of molecular conformations. The RTILs possess a unique property such as nano-heterogeneity in spite of simple molecular system. Recently, 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], reveals crystal polymorphs at low temperature. Furthermore, the intrinsic nature of the RTILs is enhanced under high pressure [1-3]. In [C4mim][PF6], a sequence of high pressure states is liquid-crystals-glass on compression process. A significant finding is that pressure induced "conformational glass" of [C4mim][PF6] was observed consistently by X-ray diffraction and Raman spectroscopy, where the maximum pressure was 8 GPa [3]. After decompression from the maximum pressure, the sample has completely recovered without dissociation or polymerization. A balancing between molecular packing efficiency and various cation conformers causes multistep frustrations only in one system.
Macroscopic and microscopic strain of SiO2 glass under uniaxial compression
Authors: Funamori Nobumasa , Wakabayashi Daisuke , Sato Tomoko , Yagi Takehiko
Published: November 2015

Although SiO2 glass is brittle due to its covalency and the lack of dislocation movement seen in crystals, it can deform without fracturing when compressed to high pressures. The phenomenon may be attributable to the well-known permanent densification by the reconstruction of the network structure consisting of SiO4 tetrahedra. To explore so-called plastic deformation without permanent densification, we measured the change in size (macroscopic strain) of uniaxially-compressed disk-shaped SiO2 glass by an optical microscope [1]. Also, to understand the anisotropy in structure (microscopic strain), we measured the azimuth-angle dependence of the position of the first sharp diffraction peak (FSDP) of uniaxially-compressed SiO2 glass with a radial X-ray diffraction technique [2]. In the microscope observation, the glass was found to deform largely without fracturing up to at least 20 GPa from 6-8 GPa, where uniaxial conditions were achieved. In the X-ray diffraction observation, a large anisotropy was found in the FSDP which corresponds to the intermediate-range network structure of the glass. The recovered glass was examined by the radial X-ray diffraction up to a high-Q range and was found to remain largely anisotropic (equivalent to about 2 GPa in differential stress) in the intermediate-range network structure and not to remain anisotropic in the short-range SiO4 tetrahedral structure. It seems intuitive that the residual anisotropy is due to the anisotropic reconstruction of the network structure during permanent densification. However, the macroscopic strain measured in the microscope observation was an order of magnitude larger than the microscopic strain in the X-ray diffraction observation, and therefore it cannot be explained solely by the anisotropic permanent densification. The permanent densification may also enhance the reconstruction of the network structure and therefore plastic deformation.
Synchrotron X-ray Scattering techniques for soft matter industrial research and development
Authors: Sztucki Michael , Burghammer Manfred , Konovalov Oleg , Mitchell Edward , Narayanan Theyencheri
Published: November 2015

Consumer products based on soft matter technology often exhibit macroscopic properties which are strongly dependent on their micro- and nano-structures extending over multiple size scales. Synchrotron scattering techniques are ideally suited for probing these multilevel structures and deliver complementary and in some cases unique information as compared to real space methods like confocal microscopy, cryo-electron microscopy or atomic force microscopy. The European Synchrotron Radiation Facility (ESRF) is a world-leading synchrotron light source which operates several state-of-the-art instruments for the investigation of soft materials and offers expertise to academic and industrial users. Fast and flexible access for proprietary experiments with a modular, fine-tuned service is guaranteed. A range of dedicated sample environments which mimic industrial processing conditions are available. This presentation will illustrate the state-of-the-art performance of the following synchrotron scattering techniques by recent examples of industrial relevance. Simultaneous small and wide angle X-ray scattering (SAXS/WAXS) is a powerful method to determine the microstructure and phase behavior of multi-component systems like detergents, food products, pharmaceutical components, polymer composites, etc. The high photon flux translates to high throughput measurements, while the high degree of collimation and resolution permit to elucidate a wide range of length scales from a few Angstroms up to micron scale. Scanning microbeam SAXS/WAXS and single micro-crystal/fiber diffraction (µXRD) allows elucidating the local nanostructure of very small objects like micro-specimens of composite organic/inorganic materials, teeth, bones, micromechanical parts, polymer fibers, micro fluidics, etc. with micro/nanometric real space resolution. X-ray reflectivity (XR) and grazing incidence diffraction/scattering (GID /GISAXS) can reveal the nanoscale structure and complexity of nano-structured complex fluids at interfaces, organic films, biological membranes, etc.
Unravelling the nanostructure of cellulose microfibrils
Authors: Thomas Lynne , Jarvis Michael
Published: November 2015

Cellulose is the most abundant naturally occurring polymer and has diverse applications in biology, energy and engineering. The cellulose nanostructure has implications on the mechanical strength of natural materials such as wood and nanocelluloses are also being used to create high-performance composite materials with properties comparable to aramid fibres and carbon nanotubes. The efficiency of breakdown of cellulose into ethanoic alcohols for biofuels is also strongly linked to the aggregation of cellulose fibres into microfibrils. Despite this, the nanostructure of cellulose microfibrils is not well understood. Neutron scattering is a powerful way to distinguish order and disorder in biological fibres, wherever the disordered regions are accessible to deuterium exchange. The aggregation of microfibrils in plant cell walls, coupled to the benefits of deuterium exchange and increased scattering contrast using neutrons gives rise to a small-angle Bragg reflection allowing the size of microfibrils to be deduced. Applying these measurements with a range of spectroscopic techniques and wide-angle X-ray and neutron scattering (WAXS, WANS) has enabled us to develop a model for the structure for the microfibrils of cellulose microfibrils in a range of plant species. The scattering data were consistent with 3nm fibrils with both hydrophobic and hydrophilic surfaces exposed. Disorder in chain packing and hydrogen bonding were shown to increase outwards from the microfibril centre. Axial disorder could be explained in terms of twisting of the microfibrils, with implications for their biosynthesis. The disorder aspects of these microfibrils are directly related to the mechanical strength of wood and the natural variation in microfibril angle reflects this. We will present the outcome of in-situ stretching measurements of cellulose microfibrils with insights into the mechanism of the absorption of strain to further probe this mechanical strength.
PANalytical OpenLabs: Past, present and future
Authors: Nénert Gwilherm , Gertenbach Jan , Striekwold Nienke , Hilberink David , van der Kolk Annemiek , Ter Mull Bas , Fransen Martijn
Published: November 2015

PANalytical believes that a crystallographic education is essential towards developing novel materials, finding innovative solutions for dealing with the scarcity of natural resources, managing global population growth and addressing climate change. PANalytical therefore strongly supports IYCr2014 organizing `OpenLabs': crystallographic education in countries around the world. We will present the past OpenLabs which already took place, emphasizing the educational aspect of it. We aim to organize each OpenLab with a theme such as mining (Ghana), culture heritage (Turkey) or non-ambient crystallography (Brazil). Furthermore and updated information can be found at: http://www.panalytical.com/en/Events-overview/IYCr2014.htm
Japanese Science & Technology with Crystallography
Authors: Kurisu Genji , Sugawara Yoko , Nakagawa Atsushi , Takata Masaki
Published: November 2015

Divers Japanese Science and Technology has advanced together with the progress of crystallography in biology, chemistry, physics, materials science, metallurgy, electronics, engineering, geoscience, etc. Based on the highly scientific and crystallographic technology, Japan has been a great contributor in developing of high-end X-ray generator, electron microscope as well as large scale Photon Science facilities, such as Photon Factory (SR), SPring-8 (SR), J-PARC (Neutron) and SACLA (XFEL). Under such background, we promote IYCr2014 with the partnership of 36 academic societies in the field of pure and applied sciences. In the last half-century, developments in crystallography have also helped thriving manufacturing sectors such as the semiconductor, the iron and steel, the pharmaceuticals, the electronics, the textile, and the chemical industries. Some of the recent impressive outcomes in Japan are fundamental findings of photosynthesis [1] and pristine asteroid [2]. Crystallography in Japan keeps promoting our nationwide projects grappling with global problems such as environment and food, and will contribute to realize a sustainable society.
Crystallography365 and Crystals in the City: IYCr 2014 activities in Australia
Authors: Maynard-Casely Helen , Sharma Neeraj
Published: November 2015

Reflecting the strong heritage of crystallographic research in Australia, we wish to present two of the public outreach projects that are underway down-under to celebrate International year of crystallography 2014. A project that is already up and running is Crystallography365 - Blogging a crystal structure a day at http://crystallography365.wordpress.com/. Gathering a group of, principally students and early career researchers based in Australia, each day during 2014 a different crystal structure will be presented and described. The goals of the project is to present the wide range of uses crystal structures have to a broad spectrum of sciences, and to provide an outlet for this group of scientists to engage with International Year of Crystallography. The other (hopefully bigger) project is Crystals in the city will run 9th-30 August 2014 (coinciding with National Science Week in Australia). A partnership between ANSTO and University of New South Wales, it will bring a public display of 10-15 person-size crystal structure models exhibited in cities around Australia. The goal is that the crystal structures will `reflect' their surroundings and instil pride among the public in the crystallographic achievements of Australian science. Accompanying the exhibition will be website, where the public can find more about each of the structures and students can learn of studying opportunities. The project will also unite a host of supporters and sponsors; universities, museums and crystallographic groups.
CrystalinItaly
Authors: Bacchi Alessia , Guerri Annalisa , Saviano Michele , Tedesco Consiglia
Published: November 2015

The actions for celebrating IYCr2014 in Italy are coordinated by the Associazione Italiana di Cristallografia (AIC), with the contribution of the Società Italiana di Mineralogia e Petrologia (SIMP) and of the Società Italiana di Luce di Sincrotrone (SILS). All the activities are gathered in a dedicated website, www.iycr2014.it, created to convey to the public and media all the information related to crystallography and on the activities that will take place in Italy. The general initiatives organized in Italy intend to be the basis for long term actions with two main objectives: to reach general public and to reach especially high school teachers. The high school teachers are key figures to build a better perception of crystallography for the next generations: previous experience in outreach and divulgation towards schools shows that teachers are highly influential to direct students' future careers. To reach high school teachers and to increase their motivation in teaching crystallography in the science syllabus, a completely new teaching pamphlet has been created, to provide a written modern, clear, and friendly instrument to learn and explain the simplest concepts related to crystallography, linked to everyday life and complemented with simple experiments. This will be distributed freely to teachers and students. To reach general public is a second important aim, where the challenge is to increase awareness of the impact that crystallography has on daily life, culture and history. An initiative to bring crystallography at everybody's door has been launched, consisting in the creation of a list of the Italian crystallographic sites, that has been put on the web site and will be implemented in an applet for smartphones. Moreover, the exhibition 'Cristalli!' is being organized in several places, having being launched in Padua with thousands of visitors in 5 months.
IYCr in Novosibirsk
Authors: Boldyreva Elena
Published: November 2015

The present contribution sums up the main activities related to celebrations of the IYCr in Novosibirsk (Russia). I give a general overview of crystallographic research and education in Novosibirsk at the Russian Academy of Sciences and at the Novosibirsk State University, to explain which basis we have for organizing various activities for children and for general public. I shall, in particular, describe the program of continuous crystallographic education starting from nursery to the university, including crystal growth courses and competitions, research projects involving children, festivals, public lectures, various competitions and exhibitions. A special attention will be paid to the activity of school-children from the French school, who have translated all the posters prepared by J.-L. Hodeau from French into Russian. The group has visited Grenoble and presented their work there, and participated also in the IYCr Opening Ceremony. Other activities include International Workshops and Conferences for students and young scientists, as well as an OpenLab in cooperation with STOE (Darmstadt).
Vision of a knowledge economy in IYCr2014
Authors: Agbenyega Jonathan
Published: November 2015

The research landscape is changing at an alarming rate, it is now impossible to talk to any professional engaged in the research community without mentioning open data, big data, new search optimisation tools, or tools geared for the digital age. Without a doubt these developments and new tools are fostering change which is revolutionising the way researchers work, share their results and interact with colleagues across the crystallographic community. Publishers too are embracing the technology shift and evidence of this can be found in many new product launches which focus on new innovative open access models, tools for analysing and quantifying masses of data, right through to bringing experts from different research departments together to discuss common problems and hopefully find novel solutions. At the International Union of Crystallography (IUCr) we have a wealth of current and historical data relevant to today's research arena in our 9 journals. What many researchers may not know however is we also have novel tools for writing and submitting articles, such as publBio and publCIF, communities such as the world directory of crystallographers and solutions such as the International Tables for Crystallography. All of these products, tools and services help our research community across a broad range of disciplines find answers they can trust in a timely manner. This presentation will explore some of the opportunities currently being explored to expand our crystallographic communities, and how we can share with and embrace other scientists employing crystallographic methods. The presentation will also look at how we can provide new and smarter products and services so we can truly reflect the interdisciplinary nature of crystallography in 2014 and beyond.
Development of teaching materials to learn crystallographic symmetry
Authors: Teshima Yoshinori , Watanabe Yasunari , Ikegami Yuji , Yamazawa Kenji , Nishio Shinsaku , Matsumoto Takeo
Published: November 2015

Authors have developed proper polyhedron models to enable people to learn the concept of three-dimensional symmetry. Touching and operating the symmetry elements of the proper polyhedron enables people to understand symmetry. In this study, authors made three-dimensional tessellation models. Certain polyhedra can be stacked in a regular periodic pattern to fill three-dimensional space completely. Figures show our models. The cube (Fig. (a)) is the only regular polyhedron to fill three-dimensional space completely. The cube is a Voronoi region of the simple cubic lattice (sc). The truncated octahedron (Fig. (b)) is the only Archimedean solid to fill three-dimensional space completely. The truncated octahedron is a Voronoi region of the body-centered cubic lattice (bcc). The rhombic dodecahedron (Fig. (c)) is the only Catalan solid (or Archimedean dual) to fill three-dimensional space completely. The rhombic dodecahedron is a Voronoi region of the face-centered cubic lattice (fcc). Figs. (a), (b), and (c) show three kinds of their aggregate respectively. In each of left-hand aggregate, there is a two-fold rotational axis along a vertical direction. In each of central aggregate, there is a three-fold rotational axis along a vertical direction. In each of right-hand aggregate, there is a four-fold rotational axis along a vertical direction. Fig. (d) is a nontrivial polyhedron to fill three-dimensional space completely. The external shape of the polyhedron was designed as a tree shape. We call such a model three-dimensional Escher shape (3DES) [1]. This can be stacked in a regular periodic pattern too.
Teaching crystallography and material science focusing on large scale facilities
Authors: Rabiller Philippe , Petry Winfried , Schmahl Wolfgang , Lamberti Carlo , Paulus Werner
Published: November 2015

Modern crystallography makes intense use of large scale facilities: neutron reactors, synchrotron sources, free electron lasers, where sources, optics and detectors allow for a wide range of possible experiments putting forwards the limits of the analysis of the structure and dynamics of matter and materials. Giving the large scale facilities a major role in the teaching of crystallography and material science, allowing for intense practice, requires to gather different skills which is more often done through summer school or intensive programs at PhD or junior scientist level. The Erasmus Mundus Master Course MaMaSELF (Master in Material Science Exploring Large Scale Facilities) is a unique European master program focused on the use of large scale facilities to investigate intimate nature of matter and materials where the five consortium higher education institutions (University of Rennes 1, France; Technische Universität München and Ludwig Maximilian University in München, Germany; University of Torino, Italy and University of Montpellier 2, France) have managed, together with Large Scale Facilities partners (ESRF, ILL, FRMII, DESY, LLB, SOLEIL, PSI) and third country partners spread out all over the world (Brazil, India, Japan, Russia, Switzerland , USA), to offer to the students a two years program at the master level including large amount of crystallography and spectroscopy teaching and an intensive summer-school totally dedicated to large scale facilities and including a large proportion of lessons and labs taught by experts, as well as many internship and master thesis opportunities at the large scale facilities.