SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE AND INFRARED-SPECTROSCOPY OF ALKALI FELDSPARS

Si-29, Al-27 MAS NMR and IR spectra of monophase K-feldspars (sanidine , orthoclase and microcline) and Na-feldspars (monalbite, anorthoclase and low albite) in different structural states have been studied. The NMR and IR spectra of K-feldspars and Na-feldspars vary regularly alo ng with their degrees of Si/Al ordering evolution. Si in orthoclase oc cupies T-2m, T-2o and T-1m, and the high-temperature Na-feldspar (mona lbite and anorthoctase) coincides in Si-29, Al-27 NMR and IR spectra. Moreover, all the high-temperature Na-feldspars and sanidine have the same Al-27 NMR and IR spectra.