Dielectric relaxation of Ca++–vacancy dipoles in KCl + KBr mixed crystals

Abstract

AbstractUsing dielectric loss and ionic thermo‐current (I.T.C.) techniques the dielectric relaxation of KCl + KBr mixed crystals doped with Ca++ was measured. It was found that the activation energy, H, for dipole reorientation decreases as the Br− minority anion concentration increases in the KCl + KBr:Ca++ mixed crystal. In KBr + KCl:Ca++ (Cl− as a minority anion) the activation energy for dipole reorientation increases as the Cl− minority anion increases. In addition to the relaxation peak that displaces with the minority Cl− anion concentration, another one was found in KBr + KCl:Ca++, but not in the KCI + KBr:Ca++ system where Br− is the minority anion. The experimental results are explained, for minority anion concentration not higher than 10%, in terms of lattice parameter change and of the local effect of the minority anion.