Method for Surface Characterization Using Solid-State Nuclear Magnetic Resonance Spectroscopy Demonstrated on Nanocrystalline ZnO:Al.

Nanoscale zinc-oxide doped with aluminum ZnO:Al is studied by different techniques targeting surface changes induced by the conditions at which ZnO:Al is used as support material in the catalysis of methanol. While it is well established that a variety of H and Al resonances can be found by solid-state NMR for this material, it was not clear yet which signals are related to species located close to the surface of the material and which to species located in the bulk. To this end, a method is suggested that makes use of a paramagnetically impregnated material to suppress NMR signals close to the particle surface in the blind sphere around the paramagnetic metal atoms.

Trace Determination and Pressure Estimation of Fluorine F Caused by Irradiation Damage in Minerals and Synthetic Fluorides.

Irradiated alkali and earth alkali halides can form metal colloids and halogen molecules, which stay trapped inside the crystal. In this paper we provide F NMR spectroscopic evidence of trapped F fluids in heavy ion-bombarded synthesized LiF crystals as well as in a variety of the mineral Villiaumite (NaF). This is the 2nd mineral in which F is unambiguously detected in nature.

Homogeneity of doping with paramagnetic ions by NMR.

In NMR, paramagnetic dopants change the relaxation behavior and the chemical shift of the nuclei in their immediate environment. Based on the concept that the "immediate environment" in a diamagnetic host material can be described as a sphere with radius r0, we developed a function for the fraction of unperturbed nuclei (the fraction of nuclei outside the sphere) which gives a link between the effective radius and the doping concentration. In the case of a homogeneous doping scenario a characteristic dependence is observed in both theory and experiment.

MH4P6N12 (M = Mg, Ca): new imidonitridophosphates with an unprecedented layered network structure type.

Isotypic imidonitridophosphates MH4P6N12 (M = Mg, Ca) have been synthesized by high-pressure/high-temperature reactions at 8 GPa and 1000 °C starting from stoichiometric amounts of the respective alkaline-earth metal nitrides, P3N5, and amorphous HPN2. Both compounds form colorless transparent platelet crystals. The crystal structures have been solved and refined from single-crystal X-ray diffraction data.

Thermally highly stable amorphous zinc phosphate intermediates during the formation of zinc phosphate hydrate.

The mechanisms by which amorphous intermediates transform into crystalline materials are still poorly understood. Here we attempt to illuminate the formation of an amorphous precursor by investigating the crystallization process of zinc phosphate hydrate. This work shows that amorphous zinc phosphate (AZP) nanoparticles precipitate from aqueous solutions prior to the crystalline hopeite phase at low concentrations and in the absence of additives at room temperature.

Low temperature synthesis of ionic phosphates in dimethyl sulfoxide.

A new synthesis route for phosphates in an organic solvent at low temperatures is presented. The synthesis was done by dispersing a nitrate salt and phosphorus pentoxide in dimethyl sulfoxide. The synthesis can be performed under water-free conditions and yielded several organic and inorganic phosphates.

The mechanism of borane-amine dehydrocoupling with bifunctional ruthenium catalysts.

Borane-amine adducts have received considerable attention, both as vectors for chemical hydrogen storage and as precursors for the synthesis of inorganic materials. Transition metal-catalyzed ammonia-borane (H3N-BH3, AB) dehydrocoupling offers, in principle, the possibility of large gravimetric hydrogen release at high rates and the formation of B-N polymers with well-defined microstructure. Several different homogeneous catalysts were reported in the literature.

C-REDOR curves of extended spin systems.

The convergence of simulated C-REDOR curves of (infinitely) large spin systems is investigated with respect to the number of spins considered in the calculations. Taking a sufficiently large number of spins (>20,000 spins) into account enables the simulation of converged C-REDOR curves over the entire time period and not only the initial regime. The calculations are based on an existing approximation within first order average Hamiltonian theory (AHT), which assumes the absence of homonuclear dipole-dipole interactions.

High-pressure synthesis and structural investigation of H3P8O8N9: a new phosphorus(V) oxonitride imide with an interrupted framework structure.

The first crystalline phosphorus oxonitride imide H(3)P(8)O(8)N(9) (=P(8)O(8)N(6)(NH)(3)) has been synthesized under high-pressure and high-temperature conditions. To this end, a new, highly reactive phosphorus oxonitride imide precursor compound was prepared and treated at 12 GPa and 750 °C by using a multianvil assembly. H(3)P(8)O(8)N(9) was obtained as a colorless, microcrystalline solid.