EFFECT OF ZRO2 ADDITION ON FZ GROWTH OF RUTILE SINGLE-CRYSTALS

Rutile single crystals free from low-angle grain boundaries were grown with the addition of ZrO2 by the floating zone (FZ) method. The number of low-angle grain boundaries were drastically reduced with the addition of ZrO2. The most effective addition was 0.5 mol%, by which low-angle grain boundaries were completely excluded over the whole crystal. Zirconium ions (Zr4+) would have a role to pin down the migration of dislocations so that the polygonization did not occur. By the analogy of the result on ZrO2 addition, trivalent titanium ions (Ti3+) may act as pinning center of dislocations as well as Zr4+, when a rutile crystal was grown under a relatively low oxygen partial pressure.