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Dive into the research topics where Edda Rädlein is active.

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Featured researches published by Edda Rädlein.


Journal of Non-crystalline Solids | 1997

Atomic force microscopy as a tool to correlate nanostructure to properties of glasses

Edda Rädlein; G. H. Frischat

Atomic force microscopy (AFM) provides high resolution images of surfaces even if they are non-conducting. Thus, glass can be investigated without conductive preparation or other complicated preparation techniques. So far, the great advantage of this microscopy in ambient atmosphere impeded atomic resolution on vitreous surfaces. However, AFM proved to be an appropriate tool for imaging the structure on a nanometre scale, of glasses, glass ceramics and coatings on glass. AFM serves to detect surface defects and changes in the overall surface topology after different treatments, such as polishing, cleaning, aging and corroding. With the help of suitable preparation, volume properties can also be investigated with a spatial resolution in the nanometre range. AFM contributions to glass research fields like fracture mechanics, crystallization, interfaces and gel consolidation are reviewed in this paper.


Journal of Non-crystalline Solids | 2001

Direct view of the structure of a silica glass fracture surface

J.-F. Poggemann; A Goß; G. Heide; Edda Rädlein; G. H. Frischat

Abstract The fracture minor surface of a silica glass, prepared at 1×10−11 mbar in the chamber of an ultra-high-vaccum-atomic-force microscope (UHV–AFM), was imaged at 1×10−8 mbar with high spatial resolution. The features directly seen were interatomic distances, e.g., O–O and Si–O, groupings of atoms, e.g., SiO4 tetrahedra and rings of tetrahedra, and network holes. A comparison with a structure calculated by a molecular dynamics simulation gave good coincidence. This direct view of the silica glass surface supports Zachariasens network structure model of glass.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1992

Radiation resistant optical glasses

Burkhard Speit; Edda Rädlein; G. H. Frischat; Alexander J. Marker; Joseph S. Hayden

Abstract Hostile environments created by short wavelength elcctromagnetic radiation, for example UV. X-ray and γ-radiation, or from particle fluxes, for example α-particles. s-particles. protons and neutrons, can produce defects within optical glasses. This loss of transmission is detrimental to the performance of the optical system and must eliminated or reduced to a manageable level. For applications within these hostile environments, radiation-stabilized optical glasses have been developed. Radiation test results will be presented, discolouration of stabilized and not stabilized glasses will be compared and colour-centers will be discussed.


Journal of Applied Physics | 2012

Photon recycling across a ultraviolet-blocking layer by luminescence in polymer solar cells

Sebastian Engmann; Marie Machalett; Vida Turkovic; Roland Rösch; Edda Rädlein; Gerhard Gobsch; Harald Hoppe

UV-blocking layers can increase the long term stability of organic solar cell devices; however, they limit the amount of light that can be utilized for energy conversion. We present photon recycling and down-conversion via a luminescent layer across a UV-blocking TiO2 layer. Our results show that the use of an additional UV-blocking layer does not necessarily reduce the overall efficiency of organic solar cells, since the loss in photocurrent due to the UV-absorption loss can be partially compensated using high energy photon down-conversion via luminescence layers.


Journal of Non-crystalline Solids | 1993

Paramagnetic centers in glasses and glass-ceramics induced by simulated space radiation

Edda Rädlein; G. H. Frischat; Burkhard Speit

Abstract The electron paramagnetic resonance spectra of optical borosilicate glass, optical lead silicate glass, and a glass-ceramic were measured in order to predict their performance in space and to identify typical radiation damages in these commercially available materials. Space radiation in low earth orbits was simulated by 0.05 to 1.35 MeV electrons, 20 MeV protons from accelerators and tungsten tube X-rays with doses ranging from 10 2 to 10 8 Gy. EPR spectra recorded at room temperature after irradiation showed that the degree of damage depends on dose, but the types of point defect do not depend on dose. Within the investigated dose ranges the EPR absorptions measurable at room temperature were similar for the three radiation types, depending on the glass composition only, but not on radiation type and dose. The following material-specific defects were identified: oxygen hole centers (OHCs) and Fe 3+ in borosilicate glass and Zerodur, the electronic centers Zn + , Ti 3+ and Zr 3+ in Zerodur and a valence change in lead silicate glass: Pb 4+ +Fe 2+ →Pb 3+ + Fe 3+ . OHC and Fe 3+ signals appear after 10 3 Gy, before macroscopic changes in transmission losses are detectable.


Journal of Sol-Gel Science and Technology | 1997

Micro- and nanostructures of Fe2O3−SiO2 sol-gel derived thick coatings

G. Mezinskis; G. H. Frischat; Edda Rädlein

Thick Fe2O3−SiO2 sol-gel coatings with 30 wt%Fe2O3 were prepared on glass substrates under different conditions. These were investigated by scanning electron and atomic force microscopies. The performance of the layers depended also on the way the substrate surface was pretreated. Annealed bulk gel pieces showed phases like FeCl2×2H2O and presumably C9Fe2O9 (300°C); at higher annealing temperatures, hematite, cristobalite and magnetite could be found.


Journal of Sol-Gel Science and Technology | 1998

Atomic Force Microscopy Study of NaOH Corroded Al2O3-TiO2-SiO2 Coatings on Glass

Yongjuan Du; Edda Rädlein; G. H. Frischat

Atomic force microscopy (AFM) was used to study the performance of ≈80 nm thick Al2O3-TiO2-SiO2 sol-gel coatings on glass substrates following corrosion in 1 M NaOH solutions at 60°C. The as-prepared coatings were homogeneous on a nanoscale and displayed the “glass pattern” before corrosion. Layers with different compositions behaved differently during the corrosion process. Thus, TiO2 or TiO2-dominated layers had tetragonal-like crystals on their surfaces after corrosion, possibly of anatase composition. On the other hand, layers with a molar ratio Al2O3 : SiO2 near 1 : 2 displayed a pseudo-hexagonal morphology, possibly with a nepheline (Na2O · Al2O3 · 2SiO2) composition. Layers of 5Al2O3-40TiO2-55SiO 2 were corroded is a stepwise fashion and had no special surface morphology.


Journal of Non-crystalline Solids | 1996

Paramagnetic centers in glasses induced by low earth orbit space radiation

G. Buchmayer; Edda Rädlein; G. H. Frischat; W. Beier; Burkhard Speit

Abstract After having been exposed to space radiation on the experimental platform Eureca (European Retrievable Carrier) for almost eleven months, different optical glasses were examined to determine radiation effects. For the 500 km high orbit with low inclination a radiation dose of 10 3 Gy is assumed. Using electron paramagnetic resonance (EPR) spectroscopy spectral components due to radiation effects were detected at room temperature. Oxygen hole centers (OHCs) were indicated in borosilicate glass, soda lime glass, phosphate crown glass, fluor crown glass and lanthanum crown glass, Ti 3+ was found in borosilicate glass. All investigated materials — excluding fused silica and fluoride glass — had differing intensities of Fe 3+ components caused by iron impurities in the samples. Comparing these results to earth specimen used in a simulation program, specially developed in preparation for the Eureca mission, the same type of radiation induced defects were identified. This confirms the validity of the simulation program as an appropriate tool to predict the performance of glass materials before space missions.


Fresenius Journal of Analytical Chemistry | 1995

Surface analysis of sol-gel coatings on glass by secondary neutral mass spectrometry

R. Ambos; Edda Rädlein; G. H. Frischat

Secondary neutral mass spectrometry (SNMS) has been used to profile coatings of the systems SiO2 and 65SiO2.20TiO2.15ZrO2 (STZ). The coatings have been deposited on float glass and heat insulating glass by dip coating from alkoxide solutions. The microporous gel coatings have been densified by heat treatment. The SBM method (separate bombardment mode) has been applied to characterize the systems and the HFM method (high frequency mode) to check for matrix effects in the SBM depth profiles. Both methods show sodium diffusion from the float glass substrate into the STZ coating and no significant sodium diffusion into the SiO2 coating. Measurements of the coatings on the heat insulating glass indicate that the SnO2 interlayer acts as a diffusion barrier. The diffusion of sodium from the float glass substrate into the STZ coating during consolidation has been analyzed by SBM-SNMS. The sputtering rate decreases with increasing consolidation. Due to large differences between sputtering rates of the substrate and of the microporous coatings, the calibration of sodium intensities from time to depth at the interface has not been possible. However, a correlation between the final temperature of heat treatment and the depth of the Na2O depletion in the substrate surface under the coating can be obtained.


Physics and Chemistry of Glasses | 1999

Preparation, nanostructure and properties of indium tin oxide (ITO) films on glass substrates. Part 1. Preparation and nanostructure

Jian Liu; Edda Rädlein; G. H. Frischat

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Chun Wang

University of Bayreuth

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Boris Goj

Technische Universität Ilmenau

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F. Rauch

Goethe University Frankfurt

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Heike Bartsch

Technische Universität Ilmenau

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Jens Müller

Technische Universität Ilmenau

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S. Krischok

Technische Universität Ilmenau

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