Resolution of Factors Responsible for Difficulty in Growing Single Crystals of YAG.
Abstract
The enhanced formation of the scattering centers in Nd:YAG is attributed to the fact that the melting point of YAG is 170 deg C lower than the melting point of NdA103. Further, since aluminium ions in the neodyium aluminate are present in six-fold coordination NdA103 can easily nucleate near the solid-liquide interface where lower temperature favors reaction (1). Provided that the growth rate of Nd:YAG exceeds the kinetics of reaction (2), the second phase particles will precipitate in the growing Nd:YAG crystal and appear as scattering centers. From the experimental evidence it can be concluded that in the composition section on and near the tie line connecting NdA103 and Y3A15012 in the Nd203-Y203-A1203 ternary system, NdA103 shows an inherent property to nucleate first. To eliminate the nucleation of Nd103 during the crystal growth of Nd:YAG the thermal gradient near the solid-liquid interface has to be very steep while the melt temperature has to be kept above the temperature which prevents reaction (1). Simultaneously the speed of the interface advancement has to be set below the thermally induced flow of the melt from the solid-liquid interface. Therefore, it is apparent that with the correct growth conditions scattering center free Nd:YAG single crystals can be grown by VSOM. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 18, 1982
- Accession Number
- ADA117401
Entities
People
- Dennis J. Viechnicki
- Jaroslav L. Caslavsky
Organizations
- United States Army Research Laboratory