Research on Crystal Growth of Optical and Laser Materials.
Final rept. 1 Jul 70-31 Dec 75,
LITTON SYSTEMS INC MORRIS PLAINS N J AIRTRON DIV
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The first part of this report describes attempts to grow single crystals of zircon ZrSiO4 by flux and hydrothermal techniques. Crystals grown from a lithium tungstate melt were colored yellow brown in corners indicating absorption of a growth impurity along preferred crystallographic planes. The impurity is suspected to be iron reported in the lithium tungstate flux. Hydrothermal zircon growth was accomplished using a 3 molar aqueous KF mineralizer at about 30000 psi and 500 C. The nutrient used was ZrO2 and SiO2 powders pressed at 30000 psi and sintered at 1520 C. Due to the relatively low solubility of zircon in various molten salts, the hydrothermal method appears to be more suitable than the flux method for growing large single crystals of zircon. However, even at 600 C the hydrothermal growth rate is about 0.005 inchday. The second part describes research efforts to prepare high purity rare earth fluorides, grow single crystals of Er, Ho, and Tm doped YLiF4, and test fabricated laser rods for operation at 2.06 micrometers. All fluorides were prepared by hydrofluorination of 99.99 commercial oxides at 800 - 1200 C in a platinum reactor. Single crystal growth was performed in a N2-HF atmosphere using a top seeded solution method. A platinum furnace was developed along with a diameter control device based on continuous crystal weighing.
- Lasers and Masers
- Miscellaneous Materials