J. Rocha et al., 2-DIMENSIONAL TRIPLE-QUANTUM AL-27 MAS NMR SPECTROSCOPIC STUDY OF THEHIGH-TEMPERATURE PHASE-TRANSFORMATION OF MICROPOROUS VPI-5, Journal of physical chemistry, 100(45), 1996, pp. 17889-17892
Two-dimensional (2D) triple-quantum Al-27 magic-angle spinning (3Q MAS
) NMR spectra of VPI-5 have been recorded in situ at room temperature
and 85 degrees C. The results confirm that at 70-80 degrees C VPI-5 un
dergoes a reversible phase transformation from space group P6(3) to P6
(3)cm. This is the first study of a phase transformation by 2D MQ MAS
NMR spectroscopy.