High quality (InNb)_0.1Ti_0.9O₂ single crystal grown using optical floating zone method

A crack-free (InNb)_0.1Ti_0.9O₂ 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)_0.1Ti_0.9O₂ 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.