On the Use of Solomon Echoes in Al NMR Studies of Complex Aluminium Hydrides.

The quadrupole coupling constant C and the asymmetry parameter η have been determined for two complex aluminium hydrides from Al NMR spectra recorded for stationary samples by using the Solomon echo sequence. The thus obtained data for KAlH (C =(1.30±0.

Crystal Structures of Two Titanium Phosphate-Based Proton Conductors: Ab Initio Structure Solution and Materials Properties.

Transition-metal phosphates show a wide range of chemical compositions, variations of the valence states, and crystal structures. They are commercially used as solid-state catalysts, cathode materials in rechargeable batteries, or potential candidates for proton-exchange membranes in fuel cells. Here, we report on the successful ab initio structure determination of two novel titanium pyrophosphates, Ti(III)p and Ti(IV)p, from powder X-ray diffraction (PXRD) data.

On the preparation and NMR spectroscopic characterization of potassium aluminium tetrahydride KAlH.

Potassium aluminium tetrahydride KAlH of high phase purity (space group Pnma (62)) was synthesized via a mechanochemical route. The thus obtained material was studied by Al and K MAS NMR spectroscopy. For both nuclei precise data for the isotropic chemical shift and the quadrupole coupling at T = 295 K were derived (Al: δ = (107.

Direct Hydrogenation of Aluminum via Stabilization with Triethylenediamine: A Mechanochemical Approach to Synthesize the Triethylenediamine ⋅ AlH Adduct.

Two approaches for the synthesis of the triethylenediamine (TEDA) ⋅ AlH adduct have been discovered. Both, the mechanochemical procedure and the wet chemical method lead to crystalline products. Starting from metallic Al powder and TEDA, ball milling under a pressure of 100 bar H facilitates a direct hydrogenation of aluminum with conversions up to 90 %.

Formation of Al2H7- anions--indirect evidence of volatile AlH3 on sodium alanate using solid-state NMR spectroscopy.

After more than a decade of intense research on NaAlH(4) doped with transition metals as hydrogen storage material, the actual mechanism of the decomposition and rehydrogenation reaction is still unclear. Early on, monomeric AlH(3) was named as a possible transport shuttle for aluminium, but never observed experimentally. Here we report for the first time the trapping of volatile AlH(3) produced during the decomposition of undoped NaAlH(4) by an adduct of sodium alanate and crown ether.

On the influence of ion exchange on the local structure of the titanosilicate ETS-10.

The effect of ion exchange with different monovalent cations (NH(4)(+), K(+), Na(+) and Cs(+)) on the local structure of the titanosilicate ETS-10 has been studied by (29)Si MAS NMR and Raman spectroscopy. Although X-ray diffraction shows no significant influence of ion exchange on the long range order, ammonium exchange is found to result in substantial damage to the local structure. Ion exchange experiments with alkali cations under significantly more acidic conditions clearly show that the structural damage brought about by ammonium exchange is not caused by the low pH of the exchange solution.

Synthesis and characterization of large-pore vinyl-functionalized mesoporous silica SBA-15.

Ordered mesoporous silicas SBA-15 with high loadings of pendant vinyl groups have been synthesized via co-condensation of tetraethoxysilane (TEOS) and triethoxyvinylsilane (TEVS) templated with a triblock copolymer.