Therefore, when the bond is broken at the edge, there may be three negative charge sites on an Al-O-Si, including two Al-OH (Al-O) with -1/2 valence and one Si-O bond with -1 valence;there may be four negative charge sites on an Mg-O-Si, three Mg-OH (Mg-O) with -1/3 valence and one Si-O bond with -1 valence.