Local Structure of Nanoscopic Magnesium Hydroxide ­Fluorides Studied by Natural Abundance 25Mg Solid State NMR Spectroscopy

Abstract

AbstractAlong with X‐ray diffraction measurements, 25Mg solid state NMR experiments were performed in natural abundance at 9.4 T on crystalline and mechanically milled samples of MgO, Mg(OH)2, MgF2, and magnesium hydroxide fluorides Mg(OH)xF2–x prepared on mechanochemical and sol‐gel syntheses routes. In addition to single pulse and spin‐echo sequences, both static 1H‐25Mg CP and 19F‐25Mg CP measurements allowed the registration of 25Mg spectra in attractive short measurement times. Although an assignment of different magnesium species in magnesium hydroxide fluorides is only hardly possible, position and line shapes of 25Mg spectra of magnesium hydroxide fluorides reflect chemically reliable trends. All samples studied here show a sixfold fluorine, oxygen, or mixed fluorine / oxygen coordination of magnesium, also in highly disordered samples.