NONSTOICHIOMETRY OF THE NEW LASER HOST LICAALF6

LiCAF (LiCaAlF6) and LiSAF (LiSrAlF6) single crystals were grown by th e CZOCHRALSKI technique. DTA measurements of the grown crystals and of different mixtures within the ternary systems LiF-(MeF2)-F-II-AlF3 (M e-II = Ca, Sr) lead to the conclusion, that LiCAF melts incongruently with a deficiency of CaF2. For LiSAF congruent melting and no deviatio n from the ideal stoichiometry could be observed. From DTA results the enthalpies of fusion were determined: Delta H-LiCAF approximate to 11 0 kJ/mol, Delta H-LiSAF approximate to 80 kJ/mol. The circumstance, th at LiSAF crystals are usually reported to have much better optical pro perties in comparison to LiCAF is attributed to these differences in t he thermodynamic behaviour.