The adsorption, bonding, defect formation, and reactivity of hydrogen on different In 2 O 3 powder samples were studied by a combination of volumetric adsorption, thermal desorption, diffraction, and spectroscopic techniques. Surface reduction was observed in dry hydrogen up to 400 K, followed by reduction of surfacenear regions. Above 500 K bulk reduction, along with the formation of metallic In, sets in. Raman spectra indicate a considerable reordering of the In 2 O 3 structure in this temperature regime. Despite their TPD proven presence, the related adsorbed H-containing species were not detectable by Fourier transform infrared spectroscopy and/or Raman spectroscopy, in strong contrast to related experiments on -Ga 2 O 3 . Hydrogeninduced oxygen vacancies were found to be easily replenished by traces of water in the gas feed.

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Multi-wavelength visible-Raman spectroscopy was used to characterize HFCVD-grown nanocrystalline diamond films. The components forming the Raman spectra were evaluated following common interpretation models. The withdrawn information was correlated to film properties like grain size, morphology, roughness or refractive index derived from AFM, XRD and Ellipsometry. Full Paper: This paper demonstrates that semiconductor Te is an efficient catalyst for SWNTs growth. By using ethanol as carbon source and TeCl 4 as catalyst procursor superlong well-oriented SWNT arrays with high percentage semiconducting can be generated for various SWNT-based nanodevices fabrication and applications.

A first amine-templated uranyl selenate based upon highly porous uranyl selenate nanotubules, (C4H12N)14[(UO2)10(SeO4)17(H2O)], has been prepared in the room-temperature reaction of uranyl nitrate, butylamine, and H2SeO4 in aqueous solution. The structure consists of nanometer-scale tubular [(UO2)10(SeO4)17(H2O)]14- units packed in a hexagonal-type fashion. The tubules have elliptical cross section with outer dimensions of 25 x 23 A = 2.5 x 2.3 nm. The internal free crystallographic diameter of the tubules is 12.6 A = 1.26 nm, which is comparable to the effective pore size in large-pore zeolites. This finding demonstrates the possibility of nanostructures for actinides in higher oxidation states and opens up a new area of research and exploration.

The new compound HP-KB 3 O 5 was synthesized under highpressure/high-temperature conditions. It is the first compound exhibiting all three possible conjunctions simultaneously: corner-sharing BO 3 groups, corner-sharing BO 4

We employ atomically resolved and element-specific scanning transmission electron microscopy (STEM) to visualize in situ and at the atomic scale the crystallization and restructuring processes of two-dimensional (2D) molybdenum disulfide (MoS2) films. To this end, we deposit a model heterostructure of thin amorphous MoS2 films onto freestanding graphene membranes used as high-resolution STEM supports. Notably, during STEM imaging the energy input from the scanning electron beam leads to beam-induced crystallization and restructuring of the amorphous MoS2 into crystalline MoS2 domains, thereby emulating widely used elevated temperature MoS2 synthesis and processing conditions. We thereby directly observe nucleation, growth, crystallization, and restructuring events in the evolving MoS2 films in situ and at the atomic scale. Our observations suggest that during MoS2 processing, various MoS2 polymorphs co-evolve in parallel and that these can dynamically transform into each other. We further highlight transitions from in-plane to out-of-plane crystallization of MoS2 layers, give indication of Mo and S diffusion species, and suggest that, in our system and depending on conditions, MoS2 crystallization can be influenced by a weak MoS2/graphene support epitaxy. Our atomic-scale in situ approach thereby visualizes multiple fundamental processes that underlie the varied MoS2 morphologies observed in previous ex situ growth and processing work. Our work introduces a general approach to in situ visualize at the atomic scale the growth and restructuring mechanisms of 2D transition-metal dichalcogenides and other 2D materials.

An inorganic oxo salt, K5[(UO2)3(SeO4)5](NO3)(H2O)3.5, forms a structure based on nanoscale uranyl selenate tubules (see picture; • {UO78−} bipyramids, ○ {SeO42−} tetrahedra). The interiors of the nanotubules are occupied by K+ ions and H2O molecules.

Colorless single crystals, as well as polycrystalline samples of TiTa2O7 and TiNb2O7, were grown directly from the melt and prepared by solid-state reactions, respectively, at various temperatures between 1598 K and 1983 K. The chemical composition of the crystals was confirmed by wavelength-dispersive X-ray spectroscopy, and the crystal structures were determined using single-crystal X-ray diffraction. Structural investigations of the isostructural compounds resulted in the following basic crystallographic data: monoclinic symmetry, space group I2/m (No. 12), a = 17.6624(12) Å, b = 3.8012(3) Å, c = 11.8290(9) Å, β = 95.135(7)°, V = 790.99(10) Å(3) for TiTa2O7 and a = 17.6719(13) Å, b = 3.8006(2) Å, c = 11.8924(9) Å, β = 95.295(7)°, V = 795.33(10) Å(3), respectively, for TiNb2O7, Z = 6. Rietveld refinement analyses of the powder X-ray diffraction patterns and Raman spectroscopy were carried out to complement the structural investigations. In addition, in situ high-temperature powder X-ray diffraction experiments over the temperature range of 323-1323 K enabled the study of the thermal expansion tensors of TiTa2O7 and TiNb2O7. To determine the hardness (H), and elastic moduli (E) of the chemical compounds, nanoindentation experiments have been performed with a Berkovich diamond indenter tip. Analyses of the load-displacement curves resulted in a hardness of H = 9.0 ± 0.5 GPa and a reduced elastic modulus of Er = 170 ± 7 GPa for TiTa2O7. TiNb2O7 showed a slightly lower hardness of H = 8.7 ± 0.3 GPa and a reduced elastic modulus of Er = 159 ± 4 GPa. Spectroscopic ellipsometry of the polished specimens was employed for the determination of the optical constants n and k. TiNb2O7 as well as TiTa2O7 exhibit a very high average refractive index of nD = 2.37 and nD = 2.29, respectively, at λ = 589 nm, similar to that of diamond (nD = 2.42).