MULTIPLE-QUANTUM MAGIC-ANGLE-SPINNING NMR DETECTION OF IMPURITY PHASES IN NA2HFO3

One-dimensional Na-23 magic angle spinning (1D-MAS) NMR spectra obtain ed at 9.4 and 14.1 T from Na2HfO3 reveal three distinct sodium sites w ith widely differing NMR interaction parameters which can be accuratel y and unambiguously extracted. On exposure to atmospheric H2O and CO2 minor (similar to 5%) impurities can be detected by 1D-MAS. Complete r esolution of the different sites is possible by use of the recently in troduced two-dimensional multiple quantum technique which is used for the first time here to detect minority phases. The reaction mechanism is further elucidated by obtaining an alternative perspective from O-1 7 MAS Nh IR which reveals an amorphous HfO2-related phase is also form ed during the decomposition process.