GROWTH OF RUTILE SINGLE-CRYSTALS BY FLOATING ZONE METHOD

Rutile single crystals of optical grade were grown by the floating zone (FZ) method. The formation of low angle grain boundaries was depressed by controlling oxygen partial pressure of growth atmosphere. The upper limit of the oxygen partial pressure was 1 x 10(3) Pa to grow rutile single crystals without low angle grain boundaries. Fluctuation of refractive index was estimated to be up to 3 x 10(-6) and etch pit density on (110) plane was 5 x 10(4) cm-2 for the as-grown crystal. The extinction ratio was 55 dB for Glan-Thomson prisms made of the FZ-grown rutile. The FZ method was an excellent technique to grow rutile single crystals of optical grade.