71Ga NMR of reference GaIV, GaV, and GaVI compounds by MAS and QPASS, extension of gallium/aluminum NMR parameter correlation.

We report new measurements of NMR parameters for 71Ga in gallium bearing oxide reference compounds, ranging from perfectly ordered systems to disordered crystalline structures and their aluminate counterparts. Static, MAS, and QPASS spectra are obtained at magnetic fields ranging from 7.0 to 18.8 T. With these results we enhance the previously established correlation between isotropic chemical shifts of 71Ga and 27Al and propose a correlation between gallium and aluminum electric field gradients (EFG). This correlation shows that the EFG at 71Ga sites are generally three times greater than those at equivalent 27Al sites.