DEVELOPMENT OF HYDROTHERMAL METHOD FOR GROWING LARGE HIGH PURITY SINGLE CRYSTALS OF BERYLLIUM OXIDE, AND LEAD METANIOBATE: INITIATE GROWING SINGLE CRYSTALS OF KTN.
Progress rept. no. 5, 1 Sep-30 Nov 65,
TEM-PRES RESEARCH INC STATE COLLEGE PA
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Growth rate studies of BeO in 4N-KOH at 15,000 p.s.i. were conducted. The growth rate along the c-axis was found to increase from 0.004 inches per day at 550 C, to 0.014 inches per day at 700 C. The growth rate in the plane perpendicular to this was 0.002 inches per day. Many of the crystals were twinned along the polar axis, and this produced an apparent increase in growth rate since most of the growth occurred in the positive polar direction. A study of the subsolidus equilibrium relationships in systems of the type KNbO3-KTaO3-solution has shown that the results with KOH solutions weaker than 4 normal are not significantly different from the results using pure water. However, K2CO3 solutions produce two new phases, one stable below 300 C, and the other between 300 and 600 C. This suggests that attempts to grow KTN hydrothermally must be made above 600 C. Author