Abstract
This review deals with effects of oxygen partial pressures on the crystal growth of oxides containing transition elements. Rutile (TiO_2) and chromium-doped forsterite (Cr: Mg_2SiO_4) single crystals are successfully grown by the floating zone method. Rutile single crystals are grown under a low oxygen partial pressure of about 10^3 Pa to avoid the formation of low-angle grain boundaries. Zirconium-doping is effective to grow rutile single crystals without low-angle grain boundaries and bubble inclusions at a high growth rate of 10 mm/h under a high oxygen partial pressure of 10^5 Pa. Cr^<4+>-rich Cr: Mg_2SiO_4 single crystals are grown under a high oxygen partial pressure of 1-2 10^5 Pa, which can not be realized in the conventional Czochralski method using an iridium crucible.
