GA-71 AND GA-69 NUCLEAR-MAGNETIC-RESONANCE STUDY OF BETA-GA2O3 - RESOLUTION OF 4-FOLD AND 6-FOLD COORDINATED GA SITES IN STATIC CONDITIONS

Ga-71 and Ga-69 nuclear magnetic resonance (NMR) spectra have been obtained for beta-Ga2O3 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 beta-Ga2O3 and are reported for the first time. Due to its high quadrupolar coupling constant the Ga-IV site in beta-Ga2O3 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.