Defect centers in antimony doped NaCl crystals

The existence of both Sb²⁺ and Sb³⁺ in NaCl has been established by a series of correlated experiments like optical absorption, EPR, Electrical conductivity and dielectric loss. Sb²⁺ gives an optical band at 212 nm and in an arbitraryorientation gives an EPR signal whose direction dependence studies indicate three magnetically inequivalent sites. A vacancy occupying a second neighbour site with respect to the impurity ion satisfactorily, explains the observed spectra. The association energy of the impurity ion has been found to be 0·56 eV from ionic conductivity studies. Dielectric loss measurements give two prominent loss peaks which have been assigned to Sb²⁺ and Sb³⁺ on the basis of their temperature variation and other correlated experiments. Radiation damage reduces the Sb³⁺ content while Sb²⁺ is not affected.