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Supermicroscopes can be used to non-destructively x-ray and characterize materials. About GEMS


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Functional Material Systems

GEMS

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The specimen is inserted in the measuring station at the PETRA III X-ray source. Photo: HZG/Christian Schmid

In order to be able to develop a specific new material, the scientists have to learn as much as possible about its inner structure: how are the atoms and crystals arranged in the material, and are there troublesome fissures or pores? Information is provided by modern analytical methods, where the materials are irradiated with strong X-ray light or neutrons. To this end, the Helmholtz-Zentrum Geesthacht operates outposts at two large renowned devices – the PETRA III Synchrotron Radiation Source at the DESY Research Centre in Hamburg, and the FRM II Research Reactor in Garching near Munich, one of the most powerful neutron sources in Europe.

In order to work there as affectively as possible, the HZG has set up a skills centre – the “German Engineering Materials Science Center” (GEMS).

It offers easy access for the researchers from Geesthacht and for scientists from around the world to the research instruments. The HZG has set up several measuring stations at both the FRM II and at PETRA III, which specialise in materials research for scientists and engineers.

Measuring stations for external specialists

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The specimens can also be tested automatically. Photo: HZG/Christian Schmid

At the PETRA III storage ring, for example, experts can follow the live production of a welded seam. This is possible due to the apparatus that they developed in house, where a remote-controlled robot welds metal plates together whilst the X-ray beam from the accelerator X-rays the process and makes visible what is happening in microscopic detail. Workpieces and materials can also be examined in detail using neutrons. Unlike X-ray radiation, the neutrons primarily show the light types of atoms, particularly hydrogen. This means that neutrons make a highly-effective tool for developing new hydrogen stores based on metal hydrides.

The GEMS skills centre has measuring stations that can be accessed by external specialists: More than half of the users come from universities, other research institutes and industry. Demand is high, and the facilities are regularly fully booked. GEMS now wants to further expand its activities: a new building with preparation labs and office workstations will be built on the DESY site in Hamburg. The HZG will participate in the measuring instruments at the “European Spallation Source” (ESS), which is currently being built in Lund in Sweden and from 2020 should be generating high-intensity neutron pulses.

Synchrotron radiation: Extremely bright X-ray light

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The laborious inspections require teamwork. Photo: HZG/Christian Schmid

Synchrotron radiation is produced when fast electrons are deflected in magnetic fields. The particles then lose energy in the form of a strong, collimated X-ray beam. This allows nanometrefine structures to be identified in a material specimen – occasionally even the atoms from which the material is comprised. Using synchrotron radiation, experts can examine a very wide variety of materials: metals, as well as semiconductors, plastics and bio-molecules. One of the world’s most powerful sources of X-ray radiation is at the DESY Research Centre in Hamburg – the PETRA III storage ring.

Neutrons : Microcosmic spies

Neutrons are minuscule atomic particles which, together with protons, form the atomic nucleus. However, neutrons can also be used as probes for materials: as they are electrically neutral, they can penetrate deep into a material. The measurement data indicates how the material is structured and what processes are taking place in it. Neutrons can also penetrate larger workpieces, such as turbine blades. In addition, they can efficiently reveal hydrogen – which is important for the development of new hydrogen stores. Neutrons are generated in research reactors. One of the most powerful in the world is the FRM II in Garching near Munich.