High-temperature defect spectroscopy in ionic crystals

The first direct NMR spectroscopic evidence of defects in crystalline Li2O powders containing aliovalent impurities is reported. Quadrupole-perturbed 7Li satellite transitions are seen above 600 K, which clearly arise from interaction of lithium defects. At about 900 K structure in the satellite transitions indicates two distinct quadrupolar interactions. The relative intensity of the satellites decreases with increasing temperature, which is interpreted as thermal dissociation of an impurity-vacancy complex.