Growth and Characterization of LiCaGaF6

Optically clear LiCaGaF6 (LiCGaF) single crystals up to 15 mm length were grown by the Czochralski method from CaF2 deficient melts. The substance melts incongruently at 751°C. No significant deviations of the crystal composition from the nominal stoichiometry Li:Ca:Ga=1:1:1 could be found. X-ray structure analysis revealed that the substance crystallizes in the colquiriite type structure. LiCaGaF6 is transparent for optical wavelengths >140 - 150 nm. The thermal expansion of the trigonal crystals is ?11 = ?22 = 18.7×10-6 K-1 perpendicular [001] and ?33 = 2.7×10-6 K-1 parallel [001].