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- ItemTris(tetrahydrofuran-kO)tris[tris(thio-phen-2-yl)methanolato-kO]terbium(III)tetrahydrofuran monosolvate(Chester : International Union of Crystallography, 2011) Veith, Michael; Belot, Celine; Huch, VolkerIn the mononuclear title compound, [Tb(C13H9OS3)3(C4H8O)3]·C4H8O, the lanthanide cation is located on a threefold rotation axis and is surrounded by electron-rich ligands in an approximately octahedral geometry. One of the thienyl groups and the bound THF are disordered with 0.5:0.5 occupancy. The free THF is disordered around the threefold axis.
- ItemA novel precursor system and its application to produce tin doped indium oxide(Cambridge : Royal Society of Chemistry, 2011) Veith, Michael; Bubel, Carsten; Zimmer, MichaelA new type of precursor has been developed by molecular design and synthesised to produce tin doped indium oxide (ITO). The precursor consists of a newly developed bimetallic indium tin alkoxide, Me2In(OtBu)3Sn (Me = CH3, OtBu = OC(CH3)3), which is in equilibrium with an excess of Me2In(OtBu). This quasi single-source precursor is applied in a sol–gel process to produce powders and coatings of ITO using a one-step heat treatment process under an inert atmosphere. The main advantage of this system is the simple heat treatment that leads to the disproportionation of the bivalent Sn(II) precursor into Sn(IV) and metallic tin, resulting in an overall reduced state of the metal in the final tin doped indium oxide (ITO) material, hence avoiding the usually necessary reduction step. Solid state 119Sn-NMR measurements of powder samples confirm the appearance of Sn(II) in an amorphous gel state and of metallic tin after annealing under nitrogen. The corresponding preparation of ITO coatings by spin coating on glass leads to transparent conductive layers with a high transmittance of visible light and a low electrical resistivity without the necessity of a reduction step.
- ItemNovel single-source precursors for the fabrication of PbTiO3, PbZrO3 and Pb(Zr1-x Tix)O3 thin-films by chemical vapor deposition(Cambridge : Royal Society of Chemistry, 2011) Veith, Michael; Bender, Michael; Lehnert, Tobias; Zimmer, Michael; Jakob, AnetteLead titanate, lead zirconate, and lead zirconate titanate (PZT) films in the sub-μm-range were produced at temperatures around 400 °C using novel single-source precursors in a classical thermal CVD process. The design of two bimetallic alkoxide compounds, a lead titanate and a lead zirconate source with almost identical physical properties and complement miscibility, resulted in a new quasi-single-source PZT precursor, an azeotropic mixture that evaporates at 30 °C and at a pressure of 4 × 10−1 mbar. After thermal treatment at 650 °C, transparent (100)-oriented PZT films with remnant polarization of 20 μC cm−2 and a coercive field strength of 20 V μm−1 were achieved. An additional lead source is not required.
- ItemBi-phasic nanostructures for functional applications(Cambridge : Royal Society of Chemistry, 2012) Veith, Michael; Lee, Juseok; Miro, Marina Martinez; Akkan, C. Kaan; Dufloux, Cecile; Aktas, O. CenkBiphasic solid state composites of the type metal/metal oxide or element/element oxide can be synthesized in one pot chemical reactions using so called molecular "single source precursors". Due to their singular genesis these composites show peculiar hetero-structures based on core-shell hierarchies such as superlattices and composite nanospheres or nanowires. They exhibit superior or new functional properties compared to their individual constituent compounds. In the current work, we review in particular the synthetical and mechanistical approach of bi-phasic (Al/Al2O3) nanostructures such as nanospheres, nanowires and nanoloops using a single source precursor. Other bi-phasic materials of the general formula M/MOx (for example M = Ge, Sn, Pb) are addressed for comparison. The impact of different synthetical conditions as well as of modification of surfaces by laser techniques and their technological relevance are presented briefly. Additionally, functional applications of the prepared surfaces are explained with some outstanding case studies. These case studies are primarily concerned with their use as biomaterials and their application in medicine as well as with their use as thin films for optics and functional surfaces.
- ItemMicro-/nanostructured alumina as model surface to study topography effects on cell-surface interactions(Saarbrücke : Leibniz-Institut für Neue Materialien, 2011) Aktas, Cenk; Martinez Miró, Martina; Lee, Juseok; Brück, Stefan; Veith, Michael[no abstract available]
- ItemPTFEP-Al2O3 hybrid nanowires reducing thrombosis and biofouling(Cambridge : Royal Society of Chemistry, 2019) Haidar, Ayman; Ali, Awadelkareem A.; Veziroglu, Salih; Fiutowski, Jacek; Eichler, Hermann; Müller, Isabelle; Kiefer, Karin; Faupel, Franz; Bischoff, Markus; Veith, Michael; Aktas, Oral Cenk; Abdul-Khaliq, HashimThrombosis and bacterial infection are major problems in cardiovascular implants. Here we demonstrated that a superhydrophobic surface composed of poly(bis(2,2,2-trifluoroethoxy)phosphazene) (PTFEP)-Al2O3 hybrid nanowires (NWs) is effective to reduce both platelet adhesion/activation and bacterial adherence/colonization. The proposed approach allows surface modification of cardiovascular implants which have 3D complex geometries. © 2019 The Royal Society of Chemistry.
- ItemMicrostructure investigation of reflective coatings interference multilayers produced by sol-gel method(Saarbrücke : Leibniz-Institut für Neue Materialien, 2007) Jilavi, Mohammad H.; Sam, Ebru D.; Werner, Ulf; Oliveira, Peter W. de; Veith, Michael[no abstract available]
- ItemCorrosion inhibiting cerium compounds for chromium-free corrosion protective coatings on AA 2024(Saarbrücke : Leibniz-Institut für Neue Materialien, 2007) Schem, Michael; Schmidt, Thomas; Caparrotti, Hinka; Wittmar, Matthias; Veith, MichaelDue to the upcoming ban of chromium-containing corrosion protection coatings in the near future, there is a worldwide effort to find a replacement for chromium as a corrosion inhibitor that also exhibits self-healing properties in scratches but without the negative efects like health and environmental hazards. In the present study promising results to achieve this goal are shown by using cerium compounds incorporated into an organic-inorganic hybrid material produced by the sol-gel process. Cerium compounds like cerium nitrate, cerium nitrate plus acetylacetonate, cerium acetylacetonate, and cerium sulphate were incorporated in sol-gel coating systems. The corrosion protection properties of these coatings were determined by means of Electrochemical Impedance Spectroscopy (EIS) and in a conventional salt spray test. Furthermore, the leaching behaviour of the coatings was examined via Optical Emission Spectrometry (OES). Significant hints for self healing properties were obtained with a hybrid system doped with cerium nitrate in combination with acetylacetone.
- ItemMechanisms of bonding effected by nanoparticles in zirconia coatings applied by spraying of suspensions(Saarbrücke : Leibniz-Institut für Neue Materialien, 2008) Adam, Jens; Aslan, Mesut; Drumm, Robert; Veith, MichaelZirconia coatings consisting of a mixture of coarse and fine grained zirconia powders prepared by spraying of suspensions and subsequent thermal treatment at limited temperatures (up to 500°C) are poor in adherence and in intrinsic mechanical strength. We have shown elsewhere that mechanical properties of these coatings can be improved clearly by adding a small amount of nanoscaled zirconia. Here, the structural and the chemical development of this coating material and of the nanoparticles is examined to gain information about the underlying bonding mechanisms. The applied temperature is relatively low in comparison to the usual onset temperature of accelerated sintering. Nevertheless, the results show that diffusion controlled material transport mechanisms play their role in bonding. The condensation of surface OH groups may participate in bonding, too. These first results confirm the potential of nanoparticles to act as inorganic binder. Additional research effort to clarify the underlying mechanisms in detail is of interest. For the practical side, it can be concluded that the resulting effect of mechanical consolidation of ceramic structures at relatively low temperatures enables new ceramic applications, for example a new type of ceramic coatings on metallic substrates.
- ItemSingle source precursors for piezoelectric and optical coatings(Saarbrücke : Leibniz-Institut für Neue Materialien, 2010) Veith, Michael; Bender, Michael; Bubel, Carsten; Aktas, Cenk[no abstract available]