Amorphous silicon oxynitride powder was synthesized by nitridation of high-purity silica in ammonia at 1120°C. The resulting material was X-ray amorphous, and its chemical characteristics were determined by X-ray photoelectron spectroscopy (XPS) and "Si nuclear magnetic resonance (NMR). The XPS analysis showed a shift to lower binding energies for the Si2p peak with increasing nitrogen content. Upon initial nitridation, the full width at half maximum (FWHM) of the Si2p peak increased, but decreased again at higher nitrogen contents, thus showing the formation of a silicon oxynitride phase with a single or small range of composition. The "Si NMR analysis showed the formation of (amorphous) Si,N, (Si-N,) and possibly two oxynitride phases (Si-N,O, Si-N,O,). It is concluded that while XPS, FT-IR, and nitrogen analysis may show the formation of an homogeneous, amorphous silicon oxynitride (Si,N,O) phase, the formation of phase-pure, amorphous Si,N,O is extremely difficult via this route.

Solid‐state 29Si NMR techniques were used to characterize laser‐synthesized silicon nitride powder prepared from the reaction of silane with ammonia. When the powder is exposed to water vapor, a hydrated layer rapidly forms at the surface. A comparison of 29Si cross polarization (CP) and Bloch decay (BD)‐MAS‐NMR spectra revealed differences between surface and bulk compositions. CP‐NMR identified Si‐NHx (x = 1, 2) species with a chemical shift of −45 ppm in the as‐synthesized (unexposed) powder. In BD‐NMR spectra, the nitride resonance is observed at −48 ppm. For the hydrated powder, CP‐NMR identified additional =Si‐OH (Q3), =Si‐(OH)2 (Q2), and SiO2 (Q4) species present at the surface. The CP‐NMR spectra were corrected for TlpH relaxation effects and deconvoluted into individual components in order to extract quantitative measurements of the various species present.

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The x-ray photoemission spectroscopic (XPS) data from different pelletized samples of the 90 K superconductor Ba2YCu3O7 _ s (where S~0.2) have been obtained. The valence band spectrum (recorded at 300 and 170 K), which is composed of contributions from both the Cu 3c? and O 2p levels, is compared with the full potential linearized augmented plane wave (FLAPW) calculated electronic density-of-states (DOS) reported by Massidda et al. and Mattheiss and Hamann. The experimental data indicate a relatively low DOS at the Fermi level. Detailed measurements of the core level Cu 2p, O Is, Ba 3d, 4d, and Y 3d spectra of the superconducting and related standard materials, are presented. Data for the superconducting material were recorded in the freshly prepared form as well as after scraping in situ. The Cu 2p core level, satellite, and Auger spectra for the various samples were carefully examined in order to assess the possibility of the presence of Cu3 + ions in Ba2YCu3O7 _s. It is observed that surface reaction in air to form carbonates and hydroxides occurs readily in the superconducting material.

Macroporous sulfonated polystyrene ion exchange resin was reacted with elemental fluorine in a liquid‐phase suspension reactor at low temperature. This method gave retention of the bulk structure of the resin bead and resulted in a space‐selective distribution of fluorine across the resin bead cross‐section, as determined using 19F secondary ion mass spectroscopy (LMI‐SIMS). The polymer modification was additionally characterized using x‐ray photoelectron spectroscopy, photoacoustic IR spectrophotometry, 19F, and 13C MAS NMR spectrometry, and mercury porosimetry. © 1994 John Wiley & Sons, Inc.