The conductivities of Mn2+-doped crystals were measured at temperatures of between 25 and 300C by using capacitance bridge techniques. The resultant data were analyzed in terms of the Lidiard-Debye-Hückel model in order to deduce the defect parameters (table 14). It was found that the Frenkel defect formation enthalpy was a function of the Br/Cl ratio, and the changes mirrored the ratio of the bulk modulus to the dielectric constant. The enthalpy of motion of Ag vacancies decreased as the composition was varied from 0 to 50mol%AgCl, and then remained essentially constant. The energy of motion of the Ag interstitial decreased linearly with increasing AgCl content.

L.S.Cain: Journal of the Physics and Chemistry of Solids, 1984, 45[8-9], 907-12

Table 14

Defect Parameters for the AgBr-AgCl System

Qf: formation enthalpy of a Frenkel defect

Qv: enthalpy of motion of a Ag vacancy

Qi: enthalpy of motion of a Ag interstitial