Lattice Distortion Around Impurity Ions in Alkali Halide Crystals II. Quadrupolar Broadening of Nuclear Magnetic Resonance Lines

The nuclear magnetlc resonance of 23 Na was observed in NaCl crystals containing a systematic series of foreign ions, Li + , K + , Rb + , F - , Br - and I - as substitutional impurities. From the observed variation of absorption intensities with solute concentrations, the displacements of nearest-neighbor ions around these solutes were estimated, using the reported values of a gradient-elastic tensor. Results thus obtained are found to agree well with those calculated theoretically and those derived from x-ray data of lattice parameter changes. Observation with single crystalline samples has led to the conclusion that anisotropy of distortion is much more pronounced near the core region than in the distant region from solute ions.