Preparation and Single Crystal Growth of LiYF4 Laser Materials.
Final rept. 1 Jan-31 Dec 73,
LITTON SYSTEMS INC MORRIS PLAINS N J LAMBDA-AIRTRON DIV
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The report describes techniques for preparation of high purity fluorides suitable for laser crystal hosts. Growth methods for LiYF4 were also developed using a constant flow of HF. The YF3 and rare earth fluorides are prepared from 5 or 6-9s polycrystalline oxides. A special platinum reactor was designed to convert oxides to fluorides via an HF reaction. Trifluorides were prepared at 800-900C and melted under HF at 1050-1200C. This prevented formation of oxide and oxyfluoride impurities in the melt. Growth of LiYF4 was accomplished in a resistively heated platinum apparatus and crucible using a modified Czochralski method. Growth occurred under a fixed pressure of HF. Preliminary results gave crystals of high optical quality, free of OH-, scattering sites, and low impurity level. The procedures should be applicable to other YLF materials in volume production. Author
- Lasers and Masers