Bridged oxygen ion

X = average number of non-bridging oxygen ions per polyhedron ... 

The non-bridging oxygen ion so produced is now capable of dissociating another water molecule ... 

Fig. 8. Surface structures for SnO2(110). Large open circles are O small filled circles are Sn. (a) Stoichiometric 1x1 reconstruction with rows of bridging oxygen ions. All the surface Sn cations are in the +4 oxidation state, (b) Bare 1x1 reconstruction in which all the bridging oxygen ions are removed to leave both 4- and 5-coordmate surface Sn cations. To maintain electrostatic neutrality half the surface Sn cations are reduced to the +2 state, (c) One possible model for a (1x2) reconstruction with alternately missing rows of bridging oxygen.

The conducting ions, such as Na, populate the planes between the spinel blocks. For optimum two-dimensional ion conduction in these planes, it is preferable that not all the available sites be occupied by the mobile cations. As the temperatures increases, the mobile ions in these conducting planes become disordered and occupy positions at random. The ionic mobility of the Na in these planes is higher in the /J structure than it is in the / " structure because of the particular configuration of the bridging oxygen ions that act as obstacles to ionic motion within the plane. Na ion conduction is anisotropic and two-dimensional within these conduction planes for both the p and structures. No ionic conduction exists in a direction perpendicular to the conduction plane. 

Fig. 6.26 Neutralization of acidic silanol groups (a) and negative charge of non-bridging oxygen ions (b) in gel by sodium hydroxide. (According to [78])...

The observed decrease in the refractive index of the studied glasses accompanying to the addition of PbO or Sm203 content presented in the Fig. 6 can be considered as an indication of a decrease in number of non-bridging oxygen ions. 

Phosphate glasses find wide applications as laser media and optical windows, and more recently as bioactive materials. Phosphate glasses are characterized by the chain or network structures formed by [PO4] tetrahedrons linked through bridging oxygen ions [62], Compared to [Si04] tetrahedron, there exist a terminal double bond FM3... 

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