The paper reports on the growth of Cr³⁺:LiCaAlF₆ single crystals by the Czochralski method from a stoichiometric melt of LiF, CaF₂, and AlF₃. (Cr³⁺ doping was obtained by the replacement of about 3 Mol-% AlF₃ by the corresponding quantity CrF₃.) Only the peripheric region and the neck of the crystals have high optical quality, whereas scattering 'needles' of typically 5 multiplied by 5 multiplied by 35 micrometers cubed can be observed in the top region and very small particles very much less than 1 micrometer ('dust') can be observed in the bottom part of the crystals. By EDX element analysis performed after ion beam thinning of the samples the needles were determined to have an excess Ca content in comparison to the LiCaAlF₆ matrix. The binary compound LiAlF₄ has the highest vapor pressure in the ternary system LiF - CaF₂ - AlF₃. It can be concluded, that LiAlF₄ evaporates continuously during crystal growth, leaving in the melt CaF₂ in excess. The incongruently melting compound Ca₂AlF₇ is considered to be the most probable candidate for the observed scattering centers.

Date Published: 14 July 1997
PDF: 7 pages
Proc. SPIE 3178, Solid State Crystals: Growth and Characterization, (14 July 1997); doi: 10.1117/12.280747

Published in SPIE Proceedings Vol. 3178:
Solid State Crystals: Growth and Characterization
Jozef Zmija; Andrzej Majchrowski; Jaroslaw Rutkowski; Jerzy Zielinski, Editor(s)