High quality (InNb)0.1Ti0.9O2 single crystal grown using optical floating zone method

• (InNb)0.1Ti0.09O2 crystal is grown first time by the floating zone method.
• Crystal with high quality and large size is obtained.
• Oxygen partial pressure has an important influence on the crystal quality.
• Lower growth rate can enhance the quality of crystal.

A crack-free (InNb)0.1Ti0.9O2 single crystal of 4 mm in diameter and 30 mm in length was successfully grown by the optical floating zone method. The polycrystalline feed and seed rods for growing the (InNb)0.1Ti0.9O2 single crystal were prepared by solid-state reaction method. The oxygen partial pressure significantly affected the crystal quality of the material. As shown in reflecting polarizing microphotographs, crystals grown in air have fewer grain boundaries than those grown in pure oxygen; some air-grown crystals are completely free of grain boundaries. Compared to pure TiO2 crystal, the (Nb+In) co-doped TiO2 crystal required a lower growth rate of 5 mm/h to ensure high quality.