The Growth of Single Crystals of Doped and Undoped Yttria and Yttrium Aluminate in a Hollow Cathode Zone Refiner

摘要

The investigation was concerned with the growth of yttrium aluminate and yttrium oxide crystals by a float-zone process. The molten zone was here produced by the bombardment of high energy electrons present in a hollow cathode discharge. This technique was successfully applied to the growth of yttrium aluminate crystals. The nature of the grown boules suggests that yttrium aluminate is incongruent in its melting behavior, but, nevertheless, amenable to growth by the float-zone process. The clear water-white yttrium aluminate crystals represent the first relatively large crystals of this compound to be grown. The hollow cathode discharge environment was found suitable to carry out the controlled zone melting of yttrium oxide. However, the crystals were found to crack under the influence of the relatively large thermal gradients inherent to this technique. The experimental results indicate that auxiliary heating will eliminate this problem. The development of a suitable means of providing this auxiliary heating has not been accomplished to the degree where un-cracked crystals can be grown. (Author)