Density and mobility of anti‐frenkel defects in SrF₂ crystals

By fitting the theoretically calculated temperature‐dependent conductivity σ to the measured dependencies log σ T ÷ 1/ T the following parameters have been determined: free formation enthalpy of anti‐Frenkel defects g AF = 2.05 eV – 6.35 kT ; mobilities of F − ion vacancies F and interstitials F : v ν T = 600 exp (‐0.70 eV/ kT ) cm 2 K/Vs, v i T = 1.1 · 10 4 exp (‐0.93 eV/ kT ) cm 2 K/Vs. — The free association enthalpies of complexes consisting of single foreign ions (Sc 3+ , Y 3+ , La 3+ , Sm 3+ , Li + , K + , Na + , O − ) and the charge‐compensating defect were obtained. The vibration frequency of F − ions in the neighbourhood of F and F is changed by a factor of 2.6 and 0.6, respectively.