Fig. 1. Electron structure of water molecule^[2].

Fig. 2. Crystal structure of β-SiO₂ using tetrahedral cluster [Si-O₄]^[3].

Fig. 3. The amorphous structure of glassy silica (SiO₂) in two dimensions^[4]

Fig. 4. (a) Cluster-plus-glue-atom model^[11]; (b) the inter-cluster distance is r₃.

Fig. 5. (a)Principal cluster [Si-O₄] and [O-Si₂] in β-SiO₂ structure (space group 194). Large and small spheres are O and Si atoms, respectively; (b) molecule-like structural unit[Si-O₄]Si.

Fig. 6. The cell structure of oxides, and large atoms are O: (a) B₂O₃(P3₁); (b) B₂O₃(Cmc2₁); (c) GeO₂(P4₁2₁2); (d) P₂O₅(Pnma).

Fig. 7. Clusters in anti-fluorite Li₂O, [Li-O₄] and [O-Li₈] (principal cluster). Large spheres represent O and small spheres represent Li.

Fig. 8. Clusters in NaCl structure of Li₂O, [Ca-O₆] (principal cluster)and [O-Ca₆]. Large spheres represent O and small spheres represent Li.

Fig. 9. Clusters in α-Al₂O₃ unit cell, including [O-Al₄] and [Al-O₆] (principal cluster). Small spheres represent Al.

Fig. 10. Clusters in γ-Al₂O₃ (Al₂MgO₄ structure), including [O-Al₄], [Al-O₄] (principal cluster), and [Al-O₆]. Small spheres represent Al.

Fig. 11. The cell structure of ZnO, and small spheres represent Ti: (a) ZnO ( ); (b) ZnO (P6₃mc).

Fig. 12. Octahedral clusters [Zn-O₆] (principal cluster) and [O-Zn₆] in ZnO (NaCl structure). Small spheres represent Zn.

Fig. 13. The cell structure of TiO₂, and small spheres represent are Ti: (a) TiO₂(P4₂/mnm); (b) TiO₂(I4₁/amd); (c) TiO₂( Pbca); (d) TiO₂ (P2₁/m)