Large Bi12TiO20 single crystals:: a study of intrinsic defects and growth parameters

A study was made of the core, solid-liquid interface shape inversion and growth striations in large Bi12TiO20 crystals grown by the pulling technique, using a resistive heating furnace. A routine was defined to obtain Bi12TiO20 crystals with the required optical quality for holographic applications. The best growth parameters determined were: crystal diameter of 15 mm, crystal/crucible radius ratio of 0.3, rotation rate of 30 rpm, pulling rate of 0.2 mm/h and an angle of less than 30 degrees between the pulling direction and the crystal face to provide a smooth interface shape transition. We crystallized only about one-third of the initial volume of the liquid in each experiment. (C) 1999 Elsevier Science B.V. All rights reserved.