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 obt ained for beta-Ga2O3 at magnetic fields of 11.7 and 7.0 T with a combi nation of static and spinning samples and using echo techniques. Isotr opic chemical shifts and well constrained electric field gradient (EFG ) tensors were measured for the Ga-IV and Ga-VI sites in beta-Ga2O3 an d are reported for the first time. Due to its high quadrupolar couplin g constant the Ga-IV site in beta-Ga2O3 is only resolved in static con ditions. Analysis of spectral discontinuities obtained for different i sotopes 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 shift s and quadrupole parameters involved in solid-state gallium NMR spectr a.