Comments on the 27Al NMR visibility of aluminas

Article Abstract:

A study was conducted to examine the effect of surface area, spinning speed and paramagnetic impurities on the 27 Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) visibility in several gamma- and eta-Al2O3 samples. Results showed that the 27Al MAS NMR signal intensities at 20-15 kHz spinning decrease as the number of distorted in aluminas increases with the surface area. The 27Al MAS NMR visibility is not affected by the paramagnetic iron impurities.

Aluminum oxide

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Neutron diffraction experiments

Article Abstract:

The equilibrium position for all aotms in strontium and calcium amides and the probability density functions of the amide ions were determined in a large temperature range. The results of Fournier analysis based on high-resolution neutron powder diffraction showed a large, anisotropic spatial distribution of the probability density function, particularly for the deuterium ions. This has been attributed to strongly anisotropic librations of the amide atoms.

Molecular dynamics

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Solid state NMR

Article Abstract:

2H and 1H wide-line NMR spectroscopy were employed to investigate the molecular dynamics of amide ions in a large temperature range for strontium and calcium amides. Two different rotational processes of the amide ions on different time scales were seen for strontium and calcium amides. The first is a slow 180-degree reorientational jump of the amide ions about their 2-fold axis. The second dynamical process of the amide ion is a fast librational motion.

Calcium, Calcium (Chemical element), Strontium

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