Dislocation charge in potassium chloride temperature and divalent-impurity dependence

Abstract

Abstract Using the ultrasonic composite oscillator technique at high strain amplitudes (8 × 10−6-2 × 10−4) we have measured the equilibrium dislocation charge in bent potassium chloride single crystals doped with Ca2+ (0·02–14 p.p.m.) over the temperature range 400–730°C. The large strain amplitude ensures that dislocation displacement exceeds the Debye-Hückel screening radius so that the resulting polarization is unscreened. In the amplitude-dependent region the isoelectric temperature at which the mean charge vanished was found to decrease slowly with strain amplitude. The temperature and impurity dependences of the charge are well characterized by a straightforward model of vacancy formation at core jogs.