Electrical Conductivity of X-Irradiated KCl

Abstract

The conductivity of Harshaw KCl crystals has been measured isothermally as a function of time in the temperature range 150-200°C, after exposing the crystals at room temperature to x-ray doses sufficient to produce about ${10}^{16}F$ centers/${\mathrm{cm}}^3$. Besides the $F$ band, a $V$ band at about 5.75 ev is produced. If the $F$ band is eliminated by optical bleaching before the measurement but the $V$ band remains, the conductivity increases monotonically to an asymptotic value, which is equal to the conductivity of the unirradiated crystal for virgin samples but is lower for samples which have been annealed in air at 260°C beforehand. If both the $F$ band and the $V$ band are present, the conductivity increases more rapidly at first, and then decreases to an asymptotic value. The behavior is qualitatively similar to that previously observed in NaCl, though there are significant differences in the optical absorption spectrum and temperature dependence of the conductivity changes.