Electrical properties of doped ice

In a similar way, HF directly forms L defects, and by means of the HF-F transition forms H30 -defects. So, doping with HF leads to an increase of nujo+ l and to a decrease of Hoh- d- As a rule, the defects formed have a binding energy to an impurity centre identical to the ionization energy of impurity centres in semiconductors. Experimental studies have confirmed the effect of impurities on the electrical properties and yielded values for the ionization energy of defects. 

In conclusion, we describe two phenomena between which there exists a certain relationship. The first phenomenon consists of a high near-surface conduction of ice the near-surface layer, several nanometers in thickness, may possess a conductivity comparable with that of a macroscopic crystal. Detection of this phenomenon necessitates use of special experimental techniques (guard ring) for measuring conductivities and undoubtedly indicates a peculiar state of the protonic system in the near-surface layer . 

The second phenomenon is related to violation of the temperature dependence of concentration, described by Eqn (10.3). In fact, on formation of a pair of defects, H30 and OH , from two neutral water molecules a considerable energy is consumed in overcoming the Coulomb attraction between H30 and OH . With other defects present, this interaction is screened, which leads to a nonlinear dependence of the system energy on the defect concentration. As the temperature is increased 

Another possibility for realizing the superionic transition is associated with modification of the atomic structure in the near-surface layer. In this case anomalously high near-surface conduction of ice would then acquire a natural explanation. 

Fletcher, The Chemical Physics of Ice (University Press, Cambridge (1970)). 

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