71Ga and 69Ga nuclear magnetic resonance study of β-Ga2O3: resolution of four- and six-fold coordinated Ga sites in static conditions

Abstract 71 Ga and 69 Ga nuclear magnetic resonance (NMR) spectra have been obtained for β-Ga 2 O 3 at magnetic fields of 11.7 and 7.0 T with a combination of static and spinning samples and using echo techniques. Isotropic chemical shifts and well constrained electric field gradient (EFG) tensors were measured for the Ga IV and Ga VI sites in β-Ga 2 O 3 and are reported for the first time. Due to its high quadrupolar coupling constant the Ga IV site in β-Ga 2 O 3 is only resolved in static conditions. Analysis of spectral discontinuities obtained for different isotopes and magnetic field strengths and a method of readily obtaining very broad spectra without point by point acquisition demonstrate an approach that should be very useful in constraining the chemical shifts and quadrupole parameters involved in solid-state gallium NMR spectra.