Electric field gradient distributions about strontium nuclei in cubic and octahedrally symmetric crystal systems

Strontium nuclei (Sr-87) in natural abundance are examined with magic angle spinning (MAS) nuclear magnetic resonance (NMR) of powder samples possessing either simple cubic (SrO) or fluorite-analogue (SrCl2 and SrF2) structures. The MAS spectra of these samples reveal a sideband pattern resulting from first order quadrupolar broadening of the outer transitions brought about by imperfections in the crystal structure. These imperfections lead to a distribution of electric field gradients (efgs) that can be characterized in these cases by fitting integrated sideband intensities as a function of spectral frequency with a Lorentzian function. Strontium oxide is simple cubic and found to have an isotropic Sr-87 chemical shift of 340 +/- 1 ppm with respect to 1 M SrCl2 (aqueous) and an efg distribution with a full width at half-height (FWHH) of 50.4 +/- 2.5 kHz. Strontium chloride (anhydrous) is isostructural with fluorite and was found to have a Sr-87 chemical shift of 45.9 +/- 1.2 ppm and an efg distribution with a FWHH of 30.9 +/- 1.4 kHz. Strontium fluoride is also isostructural with fluorite and had a Sr-87 chemical shift of -13.0 +/- 1.2 ppm and an efg FWHH of 104 +/- 18 kHz.