THE GROWTH OF RARE EARTH OXIDE, GARNET AND ALUMINATE SINGLE CRYSTALS BY A HOLLOW CATHODE FLOAT-ZONE PROCESS.
Final rept. 15 Oct 67-14 Oct 68,
MATERIALS RESEARCH CORP ORANGEBURG N Y
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The crystal growth of yttrium aluminum garnet, yttrium aluminate and yttrium oxide was carried out under this program. Large garnet crystals could be successfully grown only from feed rods where a quantity of aluminum oxide was added in excess of the 3Y2O35Al2O3 stoichiometric ratio. Both doped and undoped garnets were prepared from the alumina-rich preparation. Yttrium aluminate crystals, on the other hand, were grown from stoichiometric 1Y2O31Al2O3 feed rod compositions. The problems of metastability, as well as incongruence in melting, were eliminated in this compound by the addition of 1Nd2O31Al2O3 which also served as the crystal dopant. Yttrium oxide crystals were also grown using differential feed rod scanning to compensate for evaporation losses from the molten zone. In the doped garnet, yttrium aluminate and yttrium oxide, crystal quality was limited by cracking. Author
- Fabrication Metallurgy