Bjerrum defect, hydrogen bonds

The dismption of hydrogen bonding constitutes an appealing possible explanation of the hydration force. Attard and Batchelor presented a two-dimensional lattice model, and concluded that both the preexponential factor and the decay length of the hydration force are determined by only one unknown parameter, the concentration w of Bjerrum defects in the vicinity of the surface... 

Let us suppose that the strong hydrogen-bonded chain is absolutely ordered either by a strong external electric field 8 or by the asymmetrical arrangement of side bonds (Fig. 8). Then we assume that thermally activated structural defects in a hydrogen-bonded chain (like those in ice) are practically excluded (in the similar structure system—that is, ice—the concentration of Bjerrum faults is 5x 10-7 per molecule H20, and the concentration of ions is 10-12 per molecule H20 [159]). 

A particularly important question involves the understanding of the role of crystal defects in the peculiar electrical behaviour of ice 4. Upon the application of an electric field, the solid becomes polarized by the thermally activated reorientation of the molecular dipoles. Niels Bjerrum postulated the existence of orientational defects, which represent local disruptions of the hydrogen-bond network of ice 4, to explain the microscopic origin of this phenomenon. 

The translocation mechanism is shown in Fig. 1.1a, b. It results from the coupling of (a) displacement of along a hydrogen bond and (b) transport of the H ion from this hydrogen bond to the following one. Such a mechanism can occur only in the presence of L defects, as shown in the Bjerrum theory of ice conductivity (reference 15 and... 

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