Evidence of charged dislocations by light scattering in NaCl doped with divalent impurities

The results of the simultaneous investigations of light scattering and ionic conductivity as a function of temperature are presented for NaCl crystals doped with divalent impurities for different thermal histories. Two types of light scattering maxima are observed in the range 300-930 K. The low-temperature maxima are attributed to the appearance of a new phase containing the divalent impurity, with release of cationic vacancies. The high-temperature maxima (located in the extrinsic conduction domain) are interpreted as due to the decoration of the charged dislocations. In the authors' opinion the high-temperature maximum represents direct evidence of charge dislocations.