Field sweep broadline NMR spectroscopy

A novel NMR spectrometer is described that is uniquely versatile in its ability to accurately record broad lines by sweeping the superconducting magnetic field and to perform standard high resolution solid state NMR experiments. Broadline observation is illustrated by Al-27 spectra from static samples. Such an instrument opens up many nuclei for serious study by NMR in the solid state for the first time. (C) 1998 Elsevier Science B.V. All rights reserved

A novel high temperature NMR probe design: application to O-17 studies of gel formation of zirconia

A novel optically heated high temperature, water-cooled NMR probe design is described in detail. The sample temperature is easily and accurately controlled to at least 1300 K. The probe characteristics are evaluated and the relative merits of the design discussed. Its operation is illustrated by in situ measurement of the O-17 static NMR spectra and spin-lattice relaxation times (T-1) of gel-formed zirconia (ZrO2). A characteristic doublet of crystalline monoclinic ZrO2 is clearly observed at similar to 700 K. These data represent the first in situ O-17 solid State NMR observation of the structural development of a sol-gel-produced oxide at elevated temperatures

Oxygen speciation in nanophase MgO from solid-state O-17 NMR

Nanocrystalline MgO has been sol-gel manufactured to give a range of crystallite sizes from 1.8 to 35 nm as determined by powder X-ray diffraction. A multinuclear magnetic resonance approach using C-13, O-17, and Mg-25 provides information on the atonic scale structure. It is found that despite extensive hydrolysis that -CH3 fragments persist until extensive calcination has been performed. In O-17 magic angle spinning NMR spectra three signals are detected that are assigned to MgO-like, a surface species, and a unit also like MgO but with carbon as the third nearest neighbor, demonstrating the high sensitivity of the O-17 chemical shift to local structure and its ability to detect medium-range order