Nature of 10−8 s and 10−7 s lifetimes in Al2O3

Solid-state multinuclear magnetic resonance investigation of Pyrex®

“…The presence of BO 3 resonances with larger C q and g q , i.e., greater than 2.5 MHz and 0.5, respectively, are infrequently reported for borate glasses. Trigonal boron with higher C q and g q values have been observed in calcium metaborate (CaO AE B 2 O 3 ) [37] and also for boron impurities in calcite (CaCO 3 ) [38]. There are also reports [12,34] their formation; higher concentration results in the formation of BO 3 species that have 1 or 2 non-bridging oxygen, and the presence of asymmetric BO 3 species complementing the formation of Q 3 silicon.…”