Molybdenum sulfides (MoSx, x > 2) are promising catalysts for the hydrogen evolution reaction (HER) that show high hydrogen evolution rates and potentially represent an abundant alternative to platinum. However, a complete understanding of the structure of the most active variants is still lacking. Nanocrystalline MoS2+δ was prepared by a solvothermal method and immobilized on graphene. The obtained electrodes exhibit stable HER current densities of 3 mA cm−2 at an overpotential of ~200 mV for at least 7 h. A structural analysis of the material by high-resolution transmission electron microscopy (HRTEM) show partially disordered nanocrystals of a size between 5–10 nm. Both X-ray and electron diffraction reveal large fluctuations in lattice spacing, where the average c-axis stacking is increased and the in-plane lattice parameter is locally reduced in comparison to the layered structure of crystalline MoS2. A three-dimensional structural model of MoS2+δ could be derived from the experiments, in which [Mo2S12]2− and [Mo3S13]2− clusters as well as disclinations represent the typical defects in the ideal MoS2 structure. It is suggested that the partially disordered nanostructure leads to a high density of coordinatively modified Mo sites with lower Mo–Mo distances representing the active sites for HER catalysis, and, that these structural features are more important than the S:Mo ratio for the activity.

Bragg intensities can be used to analyse crystal size distributions in a method called FXD-CSD, which is based on the fast measurement of many Bragg spots using two-dimensional detectors. This work presents the Python-based software and its graphical user interface FXD-CSD-GUI. The GUI enables user-friendly data handling and processing and provides both graphical and numerical crystal size distribution results.

A procedure for a fast X-ray-diffraction-based crystal size distribution analysis, named FXD-CSD, is presented. The method enables the user, with minimal sample preparation, to determine the crystal size distribution (CSD) of crystalline powders or polycrystalline materials, derivedviaan intensity scaling procedure from the diffraction intensities of single Bragg spots measured in spotty diffraction patterns with a two-dimensional detector. The method can be implemented on any single-crystal laboratory diffractometer and any synchrotron-based instrument with a fast-readout two-dimensional detector and a precise sample scanning axis. The intensity scaling is achievedviathe measurement of areferencesample with known CSD under identical conditions; the only other prerequisite is that the structure (factors) of bothsampleandreferencematerial must be known. The data analysis is done with a software package written in Python. A detailed account is given of each step of the procedure, including the measurement strategy and the demands on the spottiness of the diffraction rings, the data reduction and the intensity corrections needed, and the data evaluation and the requirements for the reference material. Using commercial laboratory X-ray equipment, several corundum crystal size fractions with precisely known CSD were measured and analysed to verify the accuracy and precision of the FXD-CSD method; a comparison of known and deduced CSDs shows good agreement both in mean size and in the shape of the size distribution. For the used material and diffractometer setup, the crystal size application range is one to several tens of micrometres; this range is highly material and X-ray source dependent and can easily be extended on synchrotron sources to cover the range from below 0.5 µm to over 100 µm. FXD-CSD has the potential to become a generally applicable method for CSD determination in the field of materials science and pharmaceutics, including development and quality management, as well as in various areas of fundamental research in physics, chemistry, chemical engineering, crystallography, the geological sciences and bio-crystallization. It can be used also underin situconditions for studying crystal coarsening phenomena, and delivers precise and accurate CSDs, permitting experimental tests of various theories developed to predict their evolution.

A novel X-ray diffraction based method is presented, capable of determining volume-based crystal size distribution (CSD) of polycrystalline materials and crystalline powders with unprecedented sampling statistics; the method is named fast X-ray diffraction crystal size distribution analysis (FXD-CSD). FXD-CSD can be performed with standard laboratory X-ray diffractometers equipped with a position sensitive detector and uses a software package written in Python for the data analysis. FXD-CSD is a destruction-free and generally applicable method to establish CSDs of polycrystalline materials as well as powders for sizes well below 1m up to about 100m; it even allows for studies of samples enclosed in complex environments, e.g., for insitu measurements in a furnace or in a pressure cell. To show the capability of the method the microstructural evolution of four alumina substrates with different time-spans of sintering (4, 8, 16, and 24hour at 1600 degrees C) is investigated via FXD-CSD and SEM imaging. The corresponding CSDs and average grain sizes are determined, results obtained by FXD-CSD and the line-intersection methods are compared and clear evidence for the presence of abnormal grain growth (AGG) during sintering is shown. From three tested probability density functions (PDF) describing the CSDs a log-normal PDF fits best to the volume based CSDs; the method provides size distributions with unprecedented precision opening the way to a systematic and meaningful comparison between theoretically predicted and observed CSDs.

The precipitation and dissolution behavior of niobium carbo-nitrides is of particular interest for many technical applications. Niobium-microalloyed high strength low alloy (HSLA) steels are widely used in civil construction, automobile and line pipe applications. These steels rely on thermomechanical processing. In this context, coupled processes like thin slab casting and thermomechanical rolling of microalloyed steel grades require most precise information on the precipitation state at the individual processing steps. Reasonable equations for the solubility product at thermal equilibrium can be taken from literature but kinetics is largely unknown. Conventional X-ray technology is not able to detect small volume fractions below 0.1% of nanoscale precipitates. Investigation of nanoscale niobium precipitates by transmission electron microscopy (TEM) analysis or chemical extraction methods is common practice. However, TEM suffers from statistical relevance and chemical extraction will not give information on particle distribution and orientation. Investigation by high energy synchrotron X-ray of about 100 keV offers statistical relevance as volumes of several cubic millimeters are regarded. This large reflecting sample volume allows to detect nanometer-sized particles and provides very high angular resolution leading to an exact determination of the reflection peaks. The wavelength of around 0.12 Å is able to analyze nanometer-sized particles. Due to the high energy of the applied synchrotron radiation, precipitation and dissolution reactions could be observed during thermal treatment inside a soaking furnace. The results establish this technology for analysis of nanoscale niobium carbo-nitride precipitates

In this in vitro study, magnesium plates of ZEK100 and MgCa0.8 alloy similar to common titanium alloy osteosynthesis plates were investigated as degradable biomedical materials with a focus on primary stability. Immersion tests were performed in Hank’s Balanced Salt Solution at 37℃. The bending strength of the samples was determined using the four-point bending test according to ISO 9585:1990. The initial strength of the noncorroded ZEK100 plate was 11% greater than that of the MgCa0.8 plate; both were approximately 65% weaker than a titanium plate. The bending strength was determined after 48 and 96 h of immersion in Hank’s Balanced Salt Solution; both magnesium alloys decreased by approximately 7% after immersion for 96 h. The degradation rate and the Mg2+ release of ZEK100 were lower than those of MgCa0.8. Strong pitting and filiform corrosion were observed in the MgCa0.8 samples after 96 h of immersion. The surface of the ZEK100 plates exhibited only small areas of filiform corrosion. The results of this in vitro study indicate that the ZEK100 alloy may be more suitable for biomedical applications.

Micro-alloyed High Strength Low Alloy steels (HSLA-steels) are widely used in civil construction, automobile and line pipe applications. They contain small quantities of alloying elements between 0,01 – 0,1 wt%, such as Niobium, Titanium, Vanadium, Aluminium and Nitrogen. These steels rely on thermo-mechanical rolling, a technique that simultaneously provides high strength, excellent toughness and ductility by grain refinement. Due to their low carbon content, HSLA-steels also show good welding and cold forming properties. During the rolling and cooling process, carbon precipitations up to 100 nm are formed. Depending on the hot rolling parameters like temperature, deformation rate and degree, interpasstime and cooling conditions, precipitation formation is very complex and determines changes in material properties. The most important effect of Niobium in HSLA-steels is the retardation of austenite (γ-Fe) recrystallization which provides more nuclei for the γ/α transformation and thus a finer grain size. Besides Niobium’s role in solid solution by delaying all diffusion controlled processes, its tendency to form carbides provides the dominant effect [1, 2]. The main problem in analysing Niobium carbides in HSLA steels is the low volume content of these precipitations. Therefore, transmission electron microscopy (TEM) was almost exclusively used in order to characterize the precipitations. The disadvantage of this method lies in the extensive sample preparation and the limited sample volume. High-energy synchrotron radiation, e.g.at BW5 (E~100 keV) provides a high photon flux, an excellent angular resolution in combination with low absorption. These features allow investigations of very large irradiated sample volumes (~10 mm3). The small amount of precipitates cause very low intensities of the interesting carbides in comparison with those of the ferrite ( -Fe) (Fig.1a). However, using a special secondary slit system to hide the strong iron reflections precipitates can be detected clearly (Fig.1b) [3]. Experiments with high-energy beam-line P02.1 providing even higher photon flux and higher angular resolving power can be performed without any secondary slit system.

EGU2012-13521 In Geoscience quantitative texture analysis here defined as the quantitative analysis of the crystallographic preferred orientation (CPO), is a common tool for the investigation of fabric development in mono- and polyphase rocks, their deformation histories and kinematics. Bulk texture measurements also allow the quantitative characterisation of the anisotropic physical properties of rock materials. A routine tool to measure bulk sample volumes is neutron texture diffraction, as neutrons have large penetration capabilities of several cm in geological sample materials. The new POWTEX (POWder and TEXture) Diffractometer at the neutron research reactor FRM II in Garching, Germany is designed as a high-intensity diffractometer by groups from the RWTH Aachen, Forschungszentrum Julich and the University of Gottingen. Complementary to existing neutron diffractometers (SKAT at Dubna, Russia; GEM at ISIS, UK; HIPPO at Los Alamos, USA; D20 at ILL, France; and the local STRESS-SPEC and SPODI at FRM II) the layout of POWTEX is focused on fast time-resolved experiments and the measurement of larger sample series as necessary for the study of large scale geological structures. POWTEX is a dedicated beam line for geoscientific research. Effective texture measurements without sample tilting and rotation are possible firstly by utilizing a range of neutron wavelengths simultaneously (Time-of-Flight technique) and secondly by the high detector coverage (9.8 sr) and a high flux (�~1x10 7 n/cm2s) at the sample. Furthermore the instrument and the angular detector resolution is designed also for strong recrystallisation textures as well as for weak textures of polyphase rocks. These instrument characteristics allow in-situ time-resolved texture measurements during deformation experiments on rocksalt, ice and other materials as large sample environments will be implemented at POWTEX. The in-situ deformation apparatus is operated by a uniaxial spindle drive with a maximum axial load of 250 kN, which will be redesigned to minimize shadowing effects inside the cylindrical detector. The HT deformatione experiments will be carried out in uniaxial compression or extension and an upgrade to triaxial deformation conditions is envisaged. The load frame can alternatively be used for ice deformation by inserting a cryostat cell for temperatures down to 77 K with a triaxial apparatus allowing also simple shear experiments on ice. Strain rates range between 10-8 and 10-3 s-1 reaching to at least 50% axial strain. The deformation apparatus is designed for continuous long-term deformation experiments and can be exchanged between in-situ and ex-situ placements during continuous operation inside and outside the neutron detector.

Knowing the elastic modulus of human dental enamel is of high importance since dental filling materials should posses equal mechanical properties as enamel itself. If this demand is not fulfilled, the interaction between filling and enamel is not equivalent, so that healthy enamel could be simply abrased during chewing. Hence it is astonishing that the literature shows a big variety of suggestions for the elastic modulus. This paper will give a short overview about some existing results (maybe not all) and tries to compare and evaluate them. The experiments have been done too, trying to make it more easy for the experienced reader to make up his own mind about the elastic modulus of human dental enamel.

Obtaining information about the intrinsic structure of polycrystalline materials is of prime importance owing to the anisotropic behaviour of individual crystallites. Grain orientation and its statistical distribution, i.e. the texture, have an important influence on the material properties. Crystallographic orientations play an important role in all kinds of polycrystalline materials such as metallic, geological and biological. Using synchrotron diffraction techniques the texture can be measured with high local and angular resolving power. Here methods are presented which allow the spatial orientation of the crystallites to be determined and information about the anisotropy of mechanical properties, such as elastic modulus or thermal expansion, to obtained. The methods are adapted to all crystal and several sample symmetries as well as to different phases, for example with overlapping diffraction peaks. To demonstrate the abilities of the methods, human dental enamel has been chosen, showing even overlapping diffraction peaks. Likewise it is of special interest to learn more about the orientation and anisotropic properties of dental enamel, since only basic information is available up to now. The texture of enamel has been found to be a tilted fibre texture of high strength (up to 12.5×). The calculated elastic modulus is up to 155 GPa and the thermal expansion up to 22.3 × 10(-6)°C(-1).

The knowledge about the orientation of the prisms in human dental enamel is mainly based on morphological observations (light optical, SEM, etc.). Hence there are many schematic drawings, showing the orientation as seen in the microscope. Locally resolved direct measurements of the orientations, proofing the observations, have not been done in detail up to now. X-ray diffraction methods adapted from material science are used in this study, providing directly the orientation of the crystallites in the examined positions. Hereby new and better detailed information was obtained, showing the orientation of the prisms and giving information about their intrinsic structure. Based on the measurements, existing prism orientation models can be enhanced and two structural suggestions can be made, showing possible inner building principles for the prisms. Future planned measurements will even allow deciding which of the two models is more likely.

The development of the recrystallization and annealing textures of Al-Mn alloys with 0.4, 0.7 and 1 wt.-% manganese is analyzed using specific techniques that allow the detection of changes in grain orientation during in situ annealing. In order to investigate the evolution of texture components during annealing, highly rolled samples were annealed from room temperature to 500 C at a constant heating rate. The advantage of in situ annealing experiments using synchrotron radiation is the detection of grain orientations over time, which allows observation of the development of the recrystallization and annealing textures in a sample. In fact, the recrystallization and annealing textures in the Al-0.4Mn are characterized by an interruption in the detection of most of the grain orientations between 380 and 425 C and by competition between the cube {001}< 100 >, {011}< 1-33 >, {011}< 0-11 > and rotated-cube {001}< 110 > grain orientations, where the latter is detected until the end of the experiment. In the Al-0.7Mn sample a competition between the cube {001}< 100 >, {011}< 100 >, and rotated cube {001}< 110 >, {011}< 0-11 > grain orientations is observed. In the sample with the highest manganese concentration (1 wt.-%) an unhindered grain growth of all possible grain orientations with a high amount of the {011}< 0-11 > grain orientation is observed. The evolution of the resulting local textures is discussed in terms of preferentially oriented grain growth depending on the temperature and manganese concentration.

The exoskeleton of the crustacean Homarus americanus, the American lobster, is a biological multiphase composite consisting of a crystalline organic matrix (chitin), crystalline biominerals (calcite), amorphous calcium carbonate and proteins. One special structural aspect is the occurrence of pronounced crystallographic orientations and resulting directional anisotropic mechanical properties. The crystallographic textures of chitin and calcite have been measured by wide-angle Bragg diffraction, calculating the Orientation Distribution Function (ODF) from pole figures by using the series expansion method according to Bunge. A general strong relationship can be established between the crystallographic and the resulting mechanical and physical properties.

Dental enamel is the most highly mineralized and ha rdest biological tissue in human body [1]. The mineral which the dental enamel is almost made of i s hydroxylapatite (HAP) Ca5(PO4)3(OH), which occurs in prisms. Although HAP is the hardest mineral, it can be dissolved easily in a process, which is known as enamel demineralization by lactic acid produced by bacteria. In addition, the direct consumption of acid (e.g. citr i , lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. When these processes go on too long, the damage of the dental enamel can be so big that it is dissolved co mpletely and a cavity occurs. At this point, the health of the tooth is in serious danger cause now the dental pulp and the nerve can be also affected by the caries. The best would be to go to the denti st, so that the cavity could be cleaned and filled. The materials for a dental filling vary a lot. It c ould be gold, amalgam, ceramics or plastic material . When the filling is made, the danger for the health of the tooth is repelled. However, in the progress there can occur other dangers in direct combination with the filling. The mechanical properties of the materials used to fill cavities differ signific ant from the ones of the dental enamel. In the wors t case, the filling of a tooth can damage the enamel of the opposite tooth, hence by chewing the interaction of enamel and filling is not equivalent , so that the harder filling can abrase the softer enamel of the healthy tooth at the opposite side. T his could be avoided if the mechanical properties of dental enamel would be known in detail, hence th n another filling could be searched or fabricated as an equivalent opponent for the dental en mel with equal properties. To find such a material, one has to characterize the properties of dental enamel first in detail, e.g. to get the anisotropic elastic modulus of human enamel. This c ould be done by texture analysis, hence a general strong relationship exists between crystall ographic and morphological textures and the resulting mechanical and functional anisotropy of c rystalline materials [2]. So far, the accurate arrangement of the HAP-crystals in the dental ename l is not known, only described as "highly complex" [1]. First results of the texture analysis for selected teeth are shown here.

Microstructure and texture formation in DP steels obtained by thermal treatment at temperatures of 780 °C i.e. between Ac1 and Ac3 and at 900 °C, i.e. above Ac3 and following different cooling techniques were studied by means of X-ray and electron diffraction techniques. The formation of the different structure constituents as well as substructure parameters such as blocks size and misorientation between them induced by thermal treatment was detailed analyzed. Various methods – conventional X-ray methods, high-energy synchrotron radiation and EBSD measuring – the texture of the bcc phase were applied in order to investigate their influence on the results. Beside texture heredity, a softening of the initial texture components induced by cold rolling and of related anisotropy of steels due to thermal treatment was estimated.

Dental enamel is the most highly mineralised and hardest biological tissue in human body [1]. Dental enamel is made of hydroxylapatite (HAP) - Ca5(PO4)3(OH), which is hexagonal (6/m). The lattice parameters are a = b = 0.9418 nm und c = 0.6875 nm [1]. Although HAP is a very hard mineral, it can be dissolved easily in a process which is known as enamel demineralization by lactic acid produced by bacteria. Also the direct consumption of acid (e.g. citric, lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. These processes can damage the dental enamel. It will be dissolved completely and a cavity occurs. The cavity must then be cleaned and filled. It exists a lot of dental fillings, like gold, amalgam, ceramics or polymeric materials. After filling other dangers can occur: The mechanical properties of the materials used to fill cavities can differ strongly from the ones of the dental enamel itself. In the worst case, the filling of a tooth can damage the enamel of the opposite tooth by chewing if the interaction of enamel and filling is not equivalent, so that the harder fillings can abrade the softer enamel of the healthy tooth at the opposite side. This could be avoided if the anisotropic mechanical properties of dental enamel would be known in detail, hence then another filling could be searched or fabricated as an equivalent opponent for the dental enamel with equal properties. To find such a material, one has to characterise the properties of dental enamel first in detail for the different types of teeth (incisor, canine, premolar and molar). This is here exemplary done for a human incisor tooth by texture analysis with the program MAUD from 2D synchrotron transmission images [2,3,4].