Oxford Instruments X-maxN 80 EDX detector. SEM images were acquired at 5kV and EDX spectra at 10kV Solid State NMR. Experiments were performed using a Bruker Avance I spectrometer equipped with a 9.4 T wide-bore magnet, corresponding to a 1 H Larmor frequency (0) of 400 MHz, using a Bruker 3.2 mm HXY triple resonance probe at an MAS frequency (R) of 20 kHz.