Surface reactions in Al2O3 growth from trimethylaluminium and water by atomic layer epitaxy

An investigation of catalyst/cocatalyst/support interactions in silica-supported olefin polymerization catalysts based on Cp*TiMe3*

“…No 27 Al signal was observed, as was previously reported [44], without spinning or with fast MAS, for A380 modified with AlMe 3 . In the 13 C CP/MAS NMR spectrum, two signals were observed: a sharp peak at )1 ppm, superposed on a broad peak centered at approx.…”

“…Reinterpretation of the IR spectrum led to the conclusion that (BSiO) 2 AlMe and BSiMe are the sole species on the surface of Cab-O-Sil and are present in equal amounts, as a consequence of the rearrangement of the primary grafting product (BSiO)AlMe 2 [47]. This assertion was supported by elemental analysis of AlMe 3 adsorbed on silica gel [44]. However, recent studies involving AlMe 3 -saturated MCM-41 [45] and silica gel [43] reported that a substantial amount of (BSiO)AlMe 2 persists in those materials.…”

“…The peak at )6 ppm which is clearly seen only after hydrolysis is therefore assigned to O 3 SiMe [43,44], while the peak at )1 ppm is assigned to O 2 SiMe 2 . The presence of small amounts of each of these sites was confirmed by the appearance of two signals in the 29 Si CP/MAS spectrum, Figure 7.…”

“…Most investigations of the AlMe 3 -support interaction have involved fumed silicas, notably Aerosils and Cab-O-Sils, however, studies of AlMe 3 adsorption on porous glass [40], silica gels [41][42][43][44] and MCM-41 [45,46] have also appeared. Regardless of the origin of the silica, chemisorption was suggested to involve formation of isolated three-coordinate methylaluminum and dimethylaluminum sites, associated with O or Si atoms of the surface, Scheme 2.…”

Plasma-assisted atomic layer deposition of HfNx: Tailoring the film properties by the plasma gas composition

“…Supreme thickness controllability and conformality achieved by atomic layer deposition (ALD) has been demonstrated on high surface area materials such as silica gel [12][13][14][15] and nanopowders. [16][17][18] Some works on ALD of HfN x have already been reported in the literature [19][20][21] and are summarized in Table I.…”