Abstract
The effect of the crystallographic characteristics of the surface of a specimen with special regards to the frictional charging phenomenon was investigated. Single crystal ice plates cut from samples from the Mendenhall Glacier ice of Alaska were used and the frictional electrification was measured at ambient temperatures from - 2 to -21°C in a cold room.
As a result, the following new facts, which can not be completely explained by Latham et al's and Jaccard's theories, were revealed.
In the case of an asymmetrical rubbing between pairs of faces differently orientated with respect to crystal axes, the rubbed face of the prism plane was invariably positively electrified against that of the basal plane, regardless of the temperature difference between the pairs of the rubbed faces. However, at about -6°C the electric potential of the prism plane against the basal plane was greatly reduced and became so little as to be neglected.
Moreover, as regards the asymmetrical rubbing between pairs of faces identically orientated with respect to crystal axes, the electric potential of the rubbed face with a cold spot against that of a hot spot was reversed from positive to negative at -6°C or thereabouts as the ambient temperature rose. The above tendency is taken to be the same as that found for the artificial ice formed with polycrystallization of which the size of grains is about 5 mm in diameter on an average as described in the previous paper (Magono and Shio: 1966).
The absolute magnitude of the potential was about 3 volts, which was two orders higher than the results calculated by theories over a wide temperature range except in the vicinity of -6°C.
It was concluded that the sign of charge did not depend upon the temperature difference, but upon the difference in hardness between the two rubbed faces of the specimens on the basis of the recrystallization effect of the rubbed face.
