Institute of Applied Materials

Karlsruhe, Germany

Institute of Applied Materials

Karlsruhe, Germany
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News Article | April 21, 2017
Site: www.rdmag.com

Glass is one of mankind's oldest materials. It was used as far back as in ancient Egypt and ancient Rome and has found a place now also in manufacturing technology of the 21st century. An interdisciplinary team at the KIT led by mechanical engineer Dr. Bastian E. Rapp developed a process using glass for additive manufacturing techniques. The scientists mix nanoparticles of high-purity quartz glass and a small quantity of liquid polymer and allow this mixture to be cured by light at specific points - by means of stereolithography. The material, which has remained liquid, is washed out in a solvent bath, leaving only the desired cured structure. The polymer still mixed in this glass structure is subsequently removed by heating. "The shape initially resembles that of a pound cake; it is still unstable, and therefore the glass is sintered in a final step, i.e. heated so that the glass particles are fused," explains Rapp. He conducts research at the KIT Institute of Microstructure Technology and heads a working group of chemists, electrical engineers, and biologists. The scientists present the method in the Nature journal under the title of "Three-dimensional Printing of Transparent Fused Silica Glass." The variety of 3D-printing techniques available so far have been used on polymers or metals, but never on glass. Where glass was processed into structures, for instance by melting and application by means of a nozzle, the surface turned out to be very rough, the material was porous and contained voids. "We present a new method, an innovation in materials processing, in which the material of the piece manufactured is high-purity quartz glass with the respective chemical and physical properties," explains Rapp. The glass structures made by the KIT scientists show resolutions in the range of a few micrometers - one micrometer corresponding to one thousandth of a millimeter. However, the structures may have dimensions in the range of a few centimeters, emphasizes Rapp. 3D-formed glass can be used, for instance, in data technology. "The next plus one generation of computers will use light, which requires complicated processor structures; 3D-technology could be used, for instance, to make small, complex structures out of a large number of very small optical components of different orientations," explains the mechanical engineer. For biological and medical technologies, very small analytical systems could be made out of miniaturized glass tubes. In addition, 3D-shaped microstructures of glass could be employed in a variety of optical areas, from eyeglasses meeting special requirements to lenses in laptop cameras. The development by scientists under Junior Scientist Group Leader Bastian E. Rapp is a result of the "NanoMatFutur" junior scientist funding scheme run by the German Federal Ministry for Education and Research (BMBF) to support the development of innovative materials for industry and society. The work performed by the research group headed by Rapp has been funded by the BMBF since 2014 for a total of four years to the tune of approx. € 2.8 million. "Our research benefits very much from the interdisciplinary cooperation of various KIT institutes. Besides the Institute of Microstructure Technology, colleagues of the Institute of Nuclear Waste Management and the Institute of Applied Materials, among others, are involved in the project," says Rapp.


News Article | April 21, 2017
Site: www.eurekalert.org

New procedure allows complex forms of glass to be made by 3-D-printing, publication in Nature, presentation also at Hanover Fair Glass is one of mankind's oldest materials. It was used as far back as in ancient Egypt and ancient Rome and has found a place now also in manufacturing technology of the 21st century. An interdisciplinary team at the KIT led by mechanical engineer Dr. Bastian E. Rapp developed a process using glass for additive manufacturing techniques. The scientists mix nanoparticles of high-purity quartz glass and a small quantity of liquid polymer and allow this mixture to be cured by light at specific points - by means of stereolithography. The material, which has remained liquid, is washed out in a solvent bath, leaving only the desired cured structure. The polymer still mixed in this glass structure is subsequently removed by heating. "The shape initially resembles that of a pound cake; it is still unstable, and therefore the glass is sintered in a final step, i.e. heated so that the glass particles are fused," explains Rapp. He conducts research at the KIT Institute of Microstructure Technology and heads a working group of chemists, electrical engineers, and biologists. The scientists present the method in the Nature journal under the title of "Three-dimensional Printing of Transparent Fused Silica Glass." The variety of 3D-printing techniques available so far have been used on polymers or metals, but never on glass. Where glass was processed into structures, for instance by melting and application by means of a nozzle, the surface turned out to be very rough, the material was porous and contained voids. "We present a new method, an innovation in materials processing, in which the material of the piece manufactured is high-purity quartz glass with the respective chemical and physical properties," explains Rapp. The glass structures made by the KIT scientists show resolutions in the range of a few micrometers - one micrometer corresponding to one thousandth of a millimeter. However, the structures may have dimensions in the range of a few centimeters, emphasizes Rapp. 3D-formed glass can be used, for instance, in data technology. "The next plus one generation of computers will use light, which requires complicated processor structures; 3D-technology could be used, for instance, to make small, complex structures out of a large number of very small optical components of different orientations," explains the mechanical engineer. For biological and medical technologies, very small analytical systems could be made out of miniaturized glass tubes. In addition, 3D-shaped microstructures of glass could be employed in a variety of optical areas, from eyeglasses meeting special requirements to lenses in laptop cameras. The development by scientists under Junior Scientist Group Leader Bastian E. Rapp is a result of the "NanoMatFutur" junior scientist funding scheme run by the German Federal Ministry for Education and Research (BMBF) to support the development of innovative materials for industry and society. The work performed by the research group headed by Rapp has been funded by the BMBF since 2014 for a total of four years to the tune of approx. € 2.8 million. "Our research benefits very much from the interdisciplinary cooperation of various KIT institutes. Besides the Institute of Microstructure Technology, colleagues of the Institute of Nuclear Waste Management and the Institute of Applied Materials, among others, are involved in the project," says Rapp. Videos and more information about the current publication and the precursor project can be found under http://www. The technology presented here is one of the topics shown at the KIT booth at the Hanover Fair between April 24 and 28, 2017 (Hall 2, B16 - "Research and Technology"). Further information can be found under http://www. Karlsruhe Institute of Technology (KIT) pools its three core tasks of research, higher education, and innovation in a mission. With about 9,300 employees and 25,000 students, KIT is one of the big institutions of research and higher education in natural sciences and engineering in Europe. KIT - The Research University in the Helmholtz Association For further information, please contact:


Chen R.,Institute of Nanotechnology | Chen R.,Institute of Applied Materials | Chen R.,Helmholtz Institute Ulm | Knapp M.,Institute of Applied Materials | And 15 more authors.
Physical Chemistry Chemical Physics | Year: 2015

Intercalation pseudocapacitive Li+ storage has been recognized recently in metal oxide materials, wherein Li+ intercalation into the lattice is not solid-state diffusion-limited. This may bridge the performance gap between electrochemical capacitors and battery materials. To date, only a few materials with desired crystal structure and with well-defined nanoarchitectures have been found to exhibit such attractive behaviour. Herein, we report for the first time that nanoscale spinel LiFeTiO4 as a cathode material for Li-ion batteries exhibits intercalation pseudocapacitive Li+ storage behaviour. Nanoscale LiFeTiO4 nanoparticles with native carbon coating were synthesized by a sol-gel route. A fast and large-amount of Li+ storage (up to 1.6 Li+ per formula unit over cycling) in the nanoscale LiFeTiO4 host has been achieved without compromising kinetics. ©the Owner Societies 2015.


Burck J.,Institute of Biological Interfaces IBG2 | Heissler S.,Institute of Functional Interfaces IFG | Geckle U.,Institute of Applied Materials | Ardakani M.F.,Karlsruhe Institute of Technology | And 4 more authors.
Langmuir | Year: 2013

Electrospinning is a promising method to mimic the native structure of the extracellular matrix. Collagen is the material of choice, since it is a natural fibrous structural protein. It is an open question how much the spinning process preserves or alters the native structure of collagen. There are conflicting results in the literature, mainly due to the different solvent systems in use and due to the fact that gelatin is employed as a reference state for the completely unfolded state of collagen in calculations. Here we used circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) to investigate the structure of regenerated collagen samples and scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to illuminate the electrospun nanofibers. Collagen is mostly composed of folded and unfolded structures with different ratios, depending on the applied temperature. Therefore, CD spectra were acquired as a temperature series during thermal denaturation of native calf skin collagen type I and used as a reference basis to extract the degree of collagen folding in the regenerated electrospun samples. We discussed three different approaches to determine the folded fraction of collagen, based on CD spectra of collagen from 185 to 260 nm, since it would not be sufficient to obtain simply the fraction of folded structure θ from the ellipticity at a single wavelength of 221.5 nm. We demonstrated that collagen almost completely unfolded in fluorinated solvents and partially preserved its folded structure θ in HAc/EtOH. However, during the spinning process it refolded and the PP-II fraction increased. Nevertheless, it did not exceed 42% as deduced from the different secondary structure evaluation methods, discussed here. PP-II fractions in electrospun collagen nanofibers were almost same, being independent from the initial solvent systems which were used to solubilize the collagen for electrospinning process. © 2012 American Chemical Society.


Guerdane M.,Institute of Applied Materials
Particle-Based Methods III: Fundamentals and Applications - Proceedings of the 3rd International Conference on Particle-based MethodsFundamentals and Applications, Particles 2013 | Year: 2013

We address the question of whether and how atomistic molecular dynamics (MD) simulations can be used to calibrate macroscopic phase-field (PF) models, as hierarchical multiscale approaches usually proceed. We carry out a systematic consistency analysis by confronting results from MD with predictions of PF modeling in the case of the propagation of a planar [NicZr1-c]liquid-Zrcrystal interface during solidification and melting under chemical nonequilibrium conditions. Our study illustrates clearly that the PF approach is able to describe the same aspects of physics than MD, when the key physical parameters are transferred from the latter method to the former one. We use then this consistent MD/PF multiscale model to estimate quantitatively the influence of the in-plane solid-liquid interface ordering on the growth kinetics.

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