TY - JOUR A1 - Wolf, S. E. A1 - Müller, L. A1 - Barrea, R. A1 - Kampf, C.J. A1 - Leiterer, Jork A1 - Panne, Ulrich A1 - Hoffmann, T. A1 - Emmerling, Franziska A1 - Tremel, W. T1 - Carbonate-coordinated metal complexes precede the formation of liquid amorphous mineral emulsions of divalent metal carbonates N2 - During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed. PY - 2011 DO - https://doi.org/10.1039/c0nr00761g SN - 2040-3364 SN - 2040-3372 IS - 3 SP - 1158 EP - 1165 PB - RSC Publ. CY - Cambridge AN - OPUS4-23355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kunz, C. A1 - Büttner, T.N. A1 - Naumann, B. A1 - Boehm, A.V. A1 - Gnecco, E. A1 - Bonse, Jörn A1 - Neumann, C. A1 - Turchanin, A. A1 - Müller, F.A. A1 - Gräf, S. T1 - Large-area fabrication of low- and high-spatial-frequency laser-induced periodic surface structures on carbon fibers N2 - The formation and properties of laser-induced periodic surface structures (LIPSS) were investigated on carbon fibers under irradiation of fs-laser pulses characterized by a pulse duration τ = 300 fs and a laser wavelength λ = 1025 nm. The LIPSS were fabricated in an air environment at normal incidence with different values of the laser peak fluence and number of pulses per spot. The morphology of the generated structures was characterized by using scanning electron microscopy, atomic force microscopy and Fast-Fourier transform analyses. Moreover, the material structure and the surface chemistry of the carbon fibers before and after laser irradiation was analyzed by micro Raman spectroscopy and X-ray photoelectron spectroscopy. Large areas in the cm2 range of carbon fiber arrangements were successfully processed with homogenously distributed high- and low-spatial frequency LIPSS. Beyond those distinct nanostructures, hybrid structures were realized for the very first time by a superposition of both types of LIPSS in a two-step process. The findings facilitate the fabrication of tailored LIPSS-based surface structures on carbon fibers that could be of particular interest for e.g. fiber reinforced polymers and concretes. KW - Fs-Laser KW - Laser-induced periodic surface structures (LIPSS) KW - Carbon fibers KW - Large area structuring PY - 2018 UR - https://www.sciencedirect.com/science/article/pii/S0008622318302781 DO - https://doi.org/10.1016/j.carbon.2018.03.035 SN - 0008-6223 SN - 1873-3891 VL - 133 SP - 176 EP - 185 PB - Elsevier Ltd. AN - OPUS4-44625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mouiya, M. A1 - Martynyuk, M. A1 - Kupsch, Andreas A1 - Laquai, R. A1 - Müller, Bernd R. A1 - Doyen, N.T. A1 - Tamraoui, Y. A1 - Serrano-Munoz, Itziar A1 - Huger, M. A1 - Kachanov, M. A1 - Bruno, Giovanni T1 - The stress–strain behavior of refractory microcracked aluminum titanate: The effect of zigzag microcracks and its modeling N2 - The stress–strain behavior of ceramics, such as aluminum titanate, has certain features that are unusual for brittle materials—in particular, a substantial nonlinearity under uniaxial tension, and load–unload hysteresis caused by the sharp increase of the incremental stiffness at the beginning of unloading. These features are observed experimentally and are attributed to microcracking. Here we compare different degrees of stress–strain nonlinearity of aluminum titanate materials and quantitatively model them. We use advanced mechanical testing to observe the mechanical response at room and high temperature; electron microscopy, and X-ray refraction radiography to observe the microstructural changes. Experiments show that two types of microcracks can be distinguished: (i) microcracks induced by cooling from the sintering temperature (due to heterogeneity and anisotropy of thermal expansion), with typical sizes of the order of grain size, and (ii) much larger microcracks generated by the mechanical loading. The two microcrack types produce different effects on the stress–strain curves. Such microcracks and the features of the stress–strain behavior depend on the density of the cooling-induced microcracks and on the distribution of grain sizes. They are modeled analytically and numerically. KW - Hystersis KW - Nonlinear stress-strain curve KW - Refractory KW - Stiffness KW - X-ray refraction PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-580517 DO - https://doi.org/10.1111/jace.19325 SN - 1551-2916 VL - 106 SP - 6995 EP - 7008 PB - Wiley-Blackwell CY - Oxford [u.a.] AN - OPUS4-58051 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -