THE EFFECT OF VARIATION OF THERMAL FIELD ON THE MORPHOLOGY OF BETA-BAB2O4 SINGLE-CRYSTALS GROWN BY TOP-SEEDED SOLUTION GROWTH

The construction of a furnace for the growth of single crystals from h igh temperature solutions, giving a varying temperature distribution i n the solution over a wide range, is described. This furnace has been used for growing beta-BaB2O4 (BBO) single crystals by the top-seeded s olution growth (TSSG) technique without pulling. A correlation has bee n found between the shape of the crystals obtained and the nature of t he isotherms in the solution. It is shown that by choosing a suitable temperature distribution in the solution it is possible to obtain grow th conditions of BBO crystals with a thickness commensurable with thei r diameter.