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This paper reports a comparison between two different methods used for the synthesis of amorphous Si/C/N pre-ceramics: the laser pyrolysis method, coupled with an aerosol generator, and thermolysis in a furnace in an inert gas atmosphere. The same precursor, liquid oligomethylvinylsilazane (OMVS, [−(CH 3 )Si(HCCH 2 )NH−] n ) has been chosen to establish this comparison. Laser spray pyrolysis of OMVS produces nano-sized powder particles with a specific surface area of about 120 m 2 /g. The characteristics of the as-formed Si/C/N nanopowders (chemical composition, local order, structural evolution...) are compared to those of pre-ceramic samples obtained by thermolysis in a furnace (at 800 and 1050 °C). The amorphous network of the as-pyrolysed materials mainly consists of SiC x N 4− x ( x =0,1,2) units and amorphous or sp 2 -hybridized carbon. The carbon and hydrogen contents are higher in samples obtained by laser spray pyrolysis. Heat-treatment experiments at temperatures up to 1550 °C were performed to investigate the high temperature behaviour of the various samples. Decomposition was observed at about 1500 °C.

Oxidic zirconium films prepared by chemical deposition from aqueous medium on sulfonic acid terminated self-assembled monolayers attached to an oxidized silicon surface were investigated with scanning electron microscopy and atomic force microscopy. Bulk precipitate forms in the 4 mM Zr(SO4)2 · 4H2O, 0.4 N HCl deposition medium at 343 K after approximately 30 min. Precipitate particles (200 nm and larger) were found embedded in the oxidic zirconium film and adsorbed on top of the film; they could be washed off, but patches of the film were removed. Working with unstable deposition solutions, in which homogeneous nucleation occurs, leads to preparation-inherent flaws in the film.

Amorphous11B31,9C36,8N31,3ceramic samples were produced by thermolysis of poly(borosesquicarbodiimide) of idealized formula [B2(NCN)3]nat 1100°C in inert gas atmosphere. Small angle scattering (SAS) experiments reveal, that the as-obtained ceramics are chemically inhomogeneous. Using small angle neutron and X-ray scattering measurements, the temperature dependency of the medium range order was investigated. The SAS curves show a strong temperature dependence of the Guinier-radius (RG) of the scattering regions. Contrast variation by X-ray and neutron diffraction shows that the observed SAS signal is caused by amorphous BC2N enclosing amorphous boron-nitride segregations. The fact, that the measured invariant remains constant over the whole temperature range supports the view of complete phase separation.

Functionalized self-assembled monolayers (SAMs) on single-crystal Si wafers have been used as substrates for the deposition of titania and vanadia thin films. The formation of a titanium chelate was used to stabilize an otherwise spontaneously precipitating aqueous titanium solution. Uniform titania films have been synthesized from Ti(O2)2+ in aqueous HCl solutions at 80°C on sulfonated SAMs. Vanadium oxide hydrate films, V2O5·0.7 H2O, have been directly formed from aqueous vanadate solutions on NH2-terminated SAMs at 45°C. In the as-deposited films, water molecules were intercalated between the vanadium oxide layers. Subsequent annealing at 350°C in air led to nanocrystalline V2O5.

ZnO precipitation experiments were carried out in a Trizma (tris(hydroxymethyl)aminomethane)-buffered aqueous solution at 37 °C and in the presence of three ZnO-binding 12-mer peptide pairs, which have nearly the same isoelectric point (pI). With this new approach, the influence of peptide sequences on ZnO mineralization under moderate conditions was investigated. Previous work was focused on electrostatic interactions between inorganic-binding peptides and inorganic surfaces. The precipitates were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Furthermore, the peptide binding to crystallographic planes of ZnO crystals was modeled by molecular dynamics (MD) simulation in explicit water. The binding free energies of all ZnO-binding peptides were calculated. The combined experimental and modeled results demonstrated a direct correlation between the binding strength of the peptide and the morphology of the ZnO particle, due to differences in their specific binding strength towards polar ZnO (001) and nonpolar (100) surfaces. As a consequence, the ZnO-binding peptides inhibited the growth of ZnO crystals by selective adsorption on the polar or nonpolar ZnO surfaces. This was demonstrated by comparison with a precipitation experiment under peptide-free conditions.

It is the purpose of this paper to demonstrate how ceramic products like monoliths or coatings can be prepared by using organosilicon polymers. Micro- or nanostructures of Si3N4/SiC composite materials can be designed by the synthesis and the chemical modification of the starting polymers. Depending on the select polymer the crystallite size of Si3N4 and SiC can be varied from the range of l μm to sizes below 50 nm which provides a completely powder-free process for the preparation of nanocrystalline ceramics.

We report on an alternative route to quaternary ceramics which can be prepared by polycocondensation of commercially available polysilazanes with the appropriate alkyl amides (M(NRR')X with M = B or P and subsequent pyrolysis in argon atmosphere at 1000°C. Ceramic monoliths are obtained if the modified polysilazane is crosslinked at 400°C for 3 h. After ball-milling, sieving and cold isostatic pressing the green body is directly pyrolysed to the appropriate monolith. The obtained material is amorphous to X-ray-diffraction. Investigations by electron spectroscopie imaging (ESI) in TEM indicate a homogeneous distribution of the elements M, Si, C and N (M = B, P) within a resolution of 2 nm. Upon annealing at elevated tempertures in a nitrogen atmosphere crystallization of the appropriate thermodynamically stable phases occurs around 1400°C yielding a micro/nano-, nano/nano- or micro/microcrystalline microstructure with design-tailored properties depending on the element M.

Micro-nano-structured Si3N4/SiC-composites were prepared by liquid phase sintering of either amorphous, polymer derived Si-C-N powder or SiC1+x coated OC-Si3N4 powder, followed by gas pressure sintering. The obtained microstructures were investigated by scanning and transmission electron microscopy (SEM, TEM). Nanosized SiC inclusions embedded in microcrystalline Si3N4 grains were analysed by elemental mapping with electron spectroscopie imaging (ESI).

{B[C2H4Si(CH3)NH]2[C2H4Si(CH3)N(SiH2Ph)]}n was synthesized by base-catalyzed dehydrocoupling reaction of {B[C2H4Si(CH3)NH]3}n with phenylsilane. Pyrolysis of the new polyborosilazane precursor to 1050 °C gave an amorphous material Si3.9B1.0C11N3.2, which could resist thermal degradation to 2200 °C in argon.

Amine-boranes such as pyridine- or piperazine-borane can be converted into infusible polymers by thermal crosslinking at temperatures up to 420°C. Further rise of the temperature up to 1050° C in argon results in transformation of the polymers into black residues. Microstructural (TEM/EELS, ESCA) and chemical investigations indicate the presence of single phase boron carbide nitrides which exhibit a graphite-like, turbostratic structure with a homogeneous distribution of the elements B, N, and C. Subsequent annealing at 2200° C in argon gives rise to crystallization of the pyrolytic material generating the thermodynamically stable phases BN, C, and B4C.The semiconducting properties of the X-ray amorphous boron carbide nitride synthesized at 1050°C depend on the B/N/C-ratio which can be influenced a) by the type of amine-borane-precursor and b) by the applied atmosphere (Ar or NH3) during pyrolysis.The amine-boranes can be converted into boron carbide nitride- and BN-monoliths at 1050°C under argon or reactive gas (NH3), respectively. The monoliths are transformed into composites with 91% rel. density containing BN, C, and B4C when heated up to 2200° C.

In order to improve the resistance of solution-derived zinc oxide thin films against mechanical stress, nanostructured composite systems of soft organic and brittle ZnO layers were prepared by a bio-inspired process. As the organic component, polyelectrolyte multilayers were prepared by dip-coating using polystyrene sulfonate and poly(amino acids). The organic–inorganic laminates have typical properties in common with nacre: they consist of nanocrystals in a matrix of biomolecules, they exhibit a texture and they proved to be harder than the monolithic mineral.

Hollow zinc oxide microcapsules have been synthesized by a sacrificial template route involving the chemical bath deposition of nanostructured zinc oxide thin films on sulfonate-modified polystyrene microspheres and subsequent removal of the polymer core by dissolution in a solvent or by thermolysis. Scanning electron micrographs show that uniform coating of the templates is achieved when ZnO is deposited from a solution containing zinc acetate, the polymer polyvinylpyrrolidone, and a base in methanol, and that the ZnO shells remain intact after removal of the cores. A focused ion beam is used to cut slices from the spheres and demonstrate their inner morphology and hollowness. X-ray diffraction yields evidence that the shells consist of nanocrystalline ZnO with the zincite structure.

While most forms of multicellular life have developed a calcium-based skeleton, a few specialized organisms complement their body plan with silica. However, of all recent animals, only sponges (phylum Porifera) are able to polymerize silica enzymatically mediated in order to generate massive siliceous skeletal elements (spicules) during a unique reaction, at ambient temperature and pressure. During this biomineralization process (i.e., biosilicification) hydrated, amorphous silica is deposited within highly specialized sponge cells, ultimately resulting in structures that range in size from micrometers to meters. Spicules lend structural stability to the sponge body, deter predators, and transmit light similar to optic fibers. This peculiar phenomenon has been comprehensively studied in recent years and in several approaches, the molecular background was explored to create tools that might be employed for novel bioinspired biotechnological and biomedical applications. Thus, it was discovered that spiculogenesis is mediated by the enzyme silicatein and starts intracellularly. The resulting silica nanoparticles fuse and subsequently form concentric lamellar layers around a central protein filament, consisting of silicatein and the scaffold protein silintaphin-1. Once the growing spicule is extruded into the extracellular space, it obtains final size and shape. Again, this process is mediated by silicatein and silintaphin-1, in combination with other molecules such as galectin and collagen. The molecular toolbox generated so far allows the fabrication of novel micro- and nanostructured composites, contributing to the economical and sustainable synthesis of biomaterials with unique characteristics. In this context, first bioinspired approaches implement recombinant silicatein and silintaphin-1 for applications in the field of biomedicine (biosilica-mediated regeneration of tooth and bone defects) or micro-optics (in vitro synthesis of light waveguides) with promising results.