Ein Aufbau für Röntgenkleinwinkelstreuung an Protein-Lösungen an der Synchrotronstrahlungsquelle DELTA

AAn der Vielzweck-Beamline BL9 der Dortmunder Elektronenspeicherringanlage DELTA wurde ein neuer Aufbau zur Messung der Röntgenkleinwinkelstreuung (Small Angle X-Ray Scattering, SAXS) an flüssigen Proben entwickelt und aufgebaut. Dieser ermöglicht Messungen sowohl unter Normalbedingungen als auch unter für biologische Systeme extremen Bedingungen, wie unter erhöhter oder erniedrigter Temperatur (-15°C bis +100°C), sowie unter Hochdruck von bis zu 7000 bar. Mit Hilfe des neuen Aufbaus wurden Messungen an wässrigen Lösungen der Proteine Lysozym, Insulin und Staphylokokken Nuclease (SNase) durchgeführt und um zusätzliche Messungen an externen Strahlungsquellen ergänzt. Die an Lysozym- und Insulinlösungen durchgeführten Messungen ermöglichten eine ausführliche Charakterisierung der Lösungsstruktur der jeweiligen Proteine. Darüber hinaus erfolgte eine Analyse der intermolekularen Wechselwirkungen zwischen den gelösten Proteinmolekülen, sowohl in puren Lösungen als auch in Anwesenheit von Cosolventien (Natriumchlorid, Trifluoroethanol, Glyzerin und Ethanol). Die Messungen an Lösungen des Proteins SNase wurden mit dem Ziel durchgeführt, die Einflüsse von Cosolventien (Urea, Sorbitol, Glyzerin, Kaliumsulfat, Trifluoroethanol und Trimethylamin-N-oxid) auf die druck- und temperaturinduzierte Denaturierung des Proteins zu bestimmen

Indentation-Induced Structural Changes in Vitreous Silica Probed by in-situ Small-Angle X-Ray Scattering

The transient (or permanent) structural modifications which occur during local deformation of oxide glasses are typically studied on the basis of short-range data, for example, obtained through vibrational spectroscopy. This is in contrast to macroscopic observations, where variations in material density can usually not be explained using next-neighbor correlations alone. Recent experiments employing low-frequency Raman spectroscopy have pointed-out this issue, emphasizing that the deformation behavior of glasses is mediated through structural heterogeneity and drawing an analogy to granular media. Here, we provide additional support to this understanding, using an alternative experimental method. Structural modification of vitreous silica in the stress field of a sharp diamond indenter tip was monitored by in-situ small-angle X-ray scattering. The influenced zone during loading and after unloading was compared, demonstrating that changes in the position of the first sharp diffraction peak (FSDP) directly in the center of the indent are of permanent character. On the other hand, variations in the amplitude of electron density fluctuations (AEDF) appear to fully recover after load release. The lateral extent of the modifications and their relaxation are related to the short- to intermediate-range structure and elastic heterogeneity pertinent to the glass network. With support from Finite Element Analysis, we suggest that different structural length scales govern shear deformation and isotropic compaction in vitreous silica

X-ray nanodiffraction meets materials science

The Nanofocus Endstation of MINAXS/P03 beamline at PETRA III is one of the few places providing the experimental conditions for scanning X-ray nanodiffraction. A beam with a size of 350 x 250 nm² is generated using a long focal distance focusing system. New techniques are constantly being developed at P03 with a strong focus on materials science in order to promote this powerful, yet rarely used technique in materials science.Scanning X-ray nanodiffraction is an excellent tool for materials science. It readily serves structural information with sub-µm spatial resolution from crystalline and semi-crystalline materials (metals, biomaterials, synthetic compounds). That way grain orientation, residual stress profiles, crystal structure or texture can be obtained in a non-destructive analysis. Because of the long focal distance focusing, the wide energy range of the beamline (up to 23 keV) and a hexapod based positioning system, high resolution nanodiffraction experiments can be performed on strongly absorbing metallic samples and in extended sample environments. The strong focus on materials science at P03 is best demonstrated by the wide range of experiments already performed with in situ sample environments: stretching cells for tensile tests, a cryostream for temperature control, magnetic and electric field application, a nanoindentation apparatus and a high pressure cell for measurements at high hydrostatic pressure – all of these methods were successfully combined with the high spatial resolution provided by nanofocused beam and some will be presented here

X-ray nanodiffraction with in situ nanoindentation and hydrostatic pressure

Scanning X-ray nanodiffraction (SXND) is an excellent tool for materials science. It serves structural information with sub-µm spatial resolution from crystalline and semi-crystalline materials (metals, biomaterials, synthetic compounds). That way grain orientation, residual stress profiles, crystal structure or texture can be obtained in a non-destructive analysis. Provided a sufficiently high energy and long focal distance SXND data can be recorded from strongly absorbing metallic samples and in extended sample environments, making SXND of course a highly desirable method for materials science.SXND experiments were performed with a beam size of down to 350 x 250 nm² with in situ high pressure application and in situ nanoindentation, using homebuilt sample environments and the conditions at the Nanofocus Endstation of beamline P03 (PETRA III). A hydrostatic pressure cell was used in combination with a 19 keV beam in order to record spatially resolved data from fractured non-microscopic metallic samples at isotropic hydrostatic conditions below 1 GPa. The nanoindentation setup on the other hand was used to apply directed strains of similar magnitude onto metallic samples at 15 keV in order to observe processes inducing fracture.This contribution outlines the technical realization of these experiments and presents data that demonstrates how high resolution X-ray diffraction techniques are not restricted to static and compact sample systems. As data were also recorded from high Z samples (Ag, W) it shows how SXND bears a huge potential specifically for materials science

X-ray nanodiffraction with in situ load and pressure

Scanning X-ray nanodiffraction (SXND) is an excellent tool for materials science. It readily serves structural information with sub-µm spatial resolution from crystalline and semi-crystalline materials (metals, biomaterials, synthetic compounds). That way grain orientation, residual stress profiles, crystal structure or texture can be obtained in a non-destructive analysis. Provided a sufficiently high energy and long focal distance of the SXND experiments can be performed on strongly absorbing metallic samples and in extended sample environments, making SXND of course a highly desirable method for materials science.SXND experiments were performed with a beam size of down to 350 x 250 nm² with in situ high pressure application and with in situ nanoindentation, using homebuilt sample environments and the conditions at the Nanofocus Endstation of beamline P03 (PETRA III, Hamburg). A hydrostatic pressure cell was used in combination with a 19 keV nanobeam for the first time in order to record spatially resolved data from fractured non-microscopic metallic samples at (truly isotropic) hydrostatic conditions below 1 GPa. The nanoindentation setup on the other hand was used to apply directed strains of similar magnitude onto metallic samples at 15 keV in order to observe processes inducing fracture.This contribution outlines the technical realization of these experiments and presents data that demonstrates how high resolution X-ray diffraction techniques are not restricted to static and compact sample systems. As data were also recorded from high Z samples (Ag, W) it shows how SXND bears a huge potential specifically for materials science related research

X-ray nanodiffraction meets materials science

The Micro- and Nanofocus X-ray Scattering beamline P03 of PETRA III (DESY, Hamburg) has two endstations, one of which is the Nanofocus Endstation. Operated jointly by Helmholtz Zentrum Geesthacht and the University of Kiel, it is one of the few synchrotron endstations providing the experimental conditions for scanning X-ray nanodiffraction. A beam with a size of 350 x 250 nm² is generated using a long focal distance focusing system. New techniques are constantly being developed at P03 with a strong focus on materials science in order to promote this powerful, yet rarely used technique in materials science.Scanning X-ray nanodiffraction is an excellent tool for materials science. It readily serves structural information with sub-µm spatial resolution from crystalline and semi-crystalline materials (metals, biomaterials, synthetic compounds). That way grain orientation, residual stress profiles, crystal structure or texture can be obtained in a non-destructive analysis. Because of the long focal distance focusing, the wide energy range of the beamline (up to 23 keV) and a hexapod based positioning system, high resolution nanodiffraction experiments can be performed on strongly absorbing metallic samples and in extended sample environments. The strong focus on materials science at P03 is best demonstrated by the wide range of experiments already performed with in situ sample environments: stretching cells for tensile tests, a cryostream for temperature control, magnetic and electric field application, a nanoindentation apparatus and a high pressure cell for measurements at high hydrostatic pressure – all of these methods were successfully combined with the high spatial resolution provided by nanofocused beam. This contribution will outline the details of the setup at P03 and indicate its various applications in materials science

Influence of Gradient Residual Stress and Tip Shape on Stress Fields Inside Indented TiN Hard Coating

Nanoindentation of treated surfaces, thin films, and coatings is often used as a simple method to measure their hardness and stiffness. These quantities are technologically highly relevant and allow to qualitatively compare different material and surface treatments but fail to capture the entire extent of the highly complex mechanical interaction between indenter tip and the tested surface. Many studies have addressed this question by analytical or numerical modeling, but they must rely on verification by recalculating indentation curves or ex situ microscopy of surface deformation postexperiment. Herein, results from in situ measurements of the multiaxial stress distributions forming beneath an indenter tip while the tested sample is still under load are presented. A 9 μm-thick TiN hard coating is tested in 1) as-deposited state and 2) shot-peened by Al2O3 particles, using two diamond wedges as indenter tips, with 60° and 143° opening angle, respectively. The results reveal a strong influence of the tip shape on the deformation behavior and the main stress component developing inside the sample while under load. In addition, a crack-closing effect can be attributed to the exponentially declining near-surface compressive residual stress gradient that is present in the shot-peened sample