Growth of Cr : LiCaAlF6 and Cr : LiSrAlF6 by the Czochralski method

Single crystals of chromium-doped LiCAF and LiSAF can be grown from nearly stoichiometric melts of the components LiF, AlF3, CrF3 and CaF2 or SrF2, re spectively, by the Czochralski method. The optical quality of LiSAF crystal s is usually better, as LiCAF contains more scattering particles. This diff erent behavior can be attributed to different thermodynamic properties of b oth substances: The higher melting point of LiCAF leads to higher evaporati on losses of volatile LiF and AlF3. Moreover, LiCAF melts incongruently. Th e main problem during the growth and application of LiSAF crystals is the h ighly anisotropic thermal expansion that may lead to thermal cracking. The extreme hygroscopicity of the doping agent CrF3 has to be considered for th e growth of both substances. (C) 2000 Elsevier Science B.V. All rights rese rved.