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Research outputs

As an application-oriented research organisation, Fraunhofer aims to conduct highly innovative and solution-oriented research - for the benefit of society and to strengthen the German and European economy.

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Projects

Fraunhofer is tackling the current challenges facing industry head on. By pooling their expertise and involving industrial partners at an early stage, the Fraunhofer Institutes involved in the projects aim to turn original scientific ideas into marketable products as quickly as possible.

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Researchers

Scientific achievement and practical relevance are not opposites - at Fraunhofer they are mutually dependent. Thanks to the close organisational links between Fraunhofer Institutes and universities, science at Fraunhofer is conducted at an internationally first-class level.

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Institutes

The Fraunhofer-Gesellschaft is the leading organisation for applied research in Europe. Institutes and research facilities work under its umbrella at various locations throughout Germany.

Recent Additions

  • Publication
    Glass Molding Tools Fabricated with Selective Laser-induced Etching for Sustainable Treatment of Solid-State Electrolytes
    ( 2024)
    Peters, Christian
    ;
    Geppert, Benjamin
    ;
    Dashjav, Enkhtsetseg
    ;
    Kratz, Martin Thomas
    ;
    Tietz, Frank
    Selective laser-induced etching enables the high-precision fabrication of three-dimensional com ponents from transparent materials. First, ultrashort pulsed, tightly focused laser radiation is used to create a modification within the bulk of the transparent material. By selectively moving the focus, entire contiguous surfaces and volumes can be modified. Subsequently, the modified areas are etched free using an etching liquid. Thus, the desired three-dimensional component is exposed and separated from the surrounding material. Using the SLE process, molding tools made of fused silica are fabri cated with functional structures of less than 150 µm in size. By molding the solid-state electrolyte foil of a sodium-based battery cell, the contact areas between the chemical components are increased to enhance the power density. Different structural geometries and dimensions are compared to increase this effect
  • Publication
    An ultra-stable high-power optical frequency comb
    ( 2024)
    Schmidt, Fabian
    ;
    Moreno, Jorge O.
    ;
    ;
    Russbueldt, Peter
    ;
    Hänsch, Theodor W.
    ;
    Udem, Thomas
    ;
    Ozawa, Akira
    Optical frequency combs are typically generated in the near-infrared wavelength range, where many mode-locked lasers operate. Nonlinear frequency conversion can then be used to extend optical frequency metrology to other spectral regions, such as the extreme ultraviolet (XUV). High-power frequency combs at the fundamental wavelength can efficiently drive nonlinear frequency conversions. Low phase noise is an important requirement because the frequency conversion process not only multiplies the carrier frequency but also the phase fluctuations. In this work, we have developed a low-noise frequency comb centered at 1030 nm with an average power of 230 W, a temporal pulse duration of 59 fs, and a peak power of 32 MW. One of the modes of the seed laser is phase-locked to a continuous wave reference laser stabilized to an ultra-stable high-finesse cavity. The residual integrated phase noise from 10 Hz to 10 MHz is 41 mrad, which is sufficiently low to address narrow transitions with kHz-level linewidths after the frequency conversion to XUV wavelengths.
  • Publication
    Kritisch für die Wertschöpfung - Rohstoffabhängigkeit der deutschen Wirtschaft
    ( 2024)
    Bähr, Cornelius
    ;
    Fritsch, Manuel
    ;
    Klink, Hilmar
    ;
    Meeßen, Fabian
    ;
    Zink, Benita
    ;
    ;
    Die zukunftsfeste Aufstellung der Versorgung Deutschlands mit mineralischen Rohstoffen ist für die Sicherung des Wirtschafts­standorts zentral. Gerade für Zukunfts­technologien und zur Begrenzung potenzieller Angebots­risiken, die sich nachteilig auf abhängige Wirtschaftszweige auswirken können, ist Versorgungs­sicherheit mit diesen Rohstoffen relevant. Dabei geht es um die gesamte Wertschöpfungs­kette von der Produktion bis zur Wiedergewinnung. Rohstoffe werden auch bereits in Gütern verarbeitet importiert und spielen hier eine Rolle. Eine von KfW Research in Auftrag gegebene und von IW Consult und Fraunhofer ISI erstellte Studie analysiert die rohstoffhaltige Wertschöpfung und Angebots­risiken entlang der Produktions- und Lieferketten für die Rohstoffe Kupfer, Lithium und die Gruppe der Seltenen Erden.

Most viewed

  • Publication
    Directing nitrogen-doped carbon support chemistry for improved aqueous phase hydrogenation catalysis
    ( 2020) ;
    Rustam, Lina
    ;
    Thomann, Ralf
    ;
    Melke, Julia
    ;
    Fischer, Anna
    ;
    White, Robin J.
    Selective hydrogenations in the aqueous phase are an important transformation in the context of developing biorefinery concepts. In this report the application and optimisation of nitrogen-doped carbon (NDC) supported Pd nanoparticles as hydrogenation catalysts is discussed in the context of directing support (e.g. N) chemistry for improved catalytic performance in the aqueous phase. As a demonstrative example, the aqueous phase hydrogenation of phenol to cyclohexanone (e.g. a platform for polyamide production) is utilised. Catalyst supports were prepared based on an initial hydrothermal synthesis to yield NDC xerogels (from biomass precursors), the chemistry of which (e.g. functionality) was directed using a secondary thermal carbonisation (Tc) step at different temperatures (i.e. 350, 550, 750, 900 and 1000 °C). After Pd introduction, it was found that size, dispersion and electronic structure of the formed nanoparticles is affected by the surface chemistry of the NDC. This consequently led to higher turn-over frequency (TOF) and stability of the prepared catalysts compared to a ""nitrogen-free"" carbon supported Pd and a commercial, carbon supported Pd (Pd/AC) catalyst. Pd/NDC 900 (featuring predominantly quaternary and pyridinic N) catalysed the complete conversion of phenol at 99% selectivity to cyclohexanone, with excellent stability over 11 recycles and no discernible catalyst sintering or leaching (in contrast to the commercial catalyst). High catalytic stability, activity and selectivity make the Pd/NDC 900 catalyst highly applicable for aqueous phase hydrogenation reactions, whilst the general principle opens scope for support tailoring for application (e.g. biorefinery hydrogenations) and the development of structure/activity relationships.
  • Publication
    Laser pulse energy conversion on sequence-specifically bound metal nanoparticles and its application for DNA manipulation
    ( 2005)
    Garwe, F.
    ;
    Czaki, A.
    ;
    Maubach, G.
    ;
    Steinbrück, A.
    ;
    Weise, A.
    ;
    König, K.
  • Publication
    Measurement of Local Recombination Activity in High Diffusion Length Semiconductors
    We present a conceptual approach for the localisation and characterisation of local sites of recombination in high diffusion length semiconductors under photovoltaic field conditions. While established imaging techniques operate in this very regime of uniform "1 sun" illumination, inevitable lateral diffusion of charge carriers veils the origin and severity of localised recombination sites. To reduce this limitation due to lateral diffusion the natural choice is using focussed charge carrier excitation and detection in combination with scanning the specimen. The resulting photoluminescence intensity maps are of high spatial resolution and may be composed of a superposition of a multitude of recombination active defects influencing each other due to the high bulk diffusion length. We demonstrate the feasibility of a self-consistent calibration of the setup quantum efficiency in such experimental condition which delivers a charge carrier density map in absolute units. A solution is presented to disentangle the superposition of local sites of recombination to isolate the actual recombination activity of every site. We demonstrate the feasibility of the approach experimentally on the high diffusion length semiconductor silicon.