Crystal growth of SnO 2 and other MO 2 (M = Ti, Zr, Hf) oxides by flux of B 2 O 3 V 2 O 5 system

Single crystals of SnO 2 and MO 2 (M = Ti, Zr, Hf) oxide were grown from flux of B 2 O 3 V 2 O 5 system. Mixtures of the flux and the starting powder of Zn 2 SnO 4 , TiO 2 , ZrO 2 , or HfO 2 were soaked at a temperature of 1030–1340°C for 10–72 hr and then were cooled down to 900°C at a rate of 5°C/hr. Grown crystals of SnO 2 were pale brown needles. An increase in V 2 O 5 content of the flux (up to V 2 O 5 /B 2 O 3 ratio equal to 2) or in the soaking temperature increases the crystal size. A largest crystal with the size of 15.0 × 0.4 × 0.4 mm was obtained in the case of V 2 O 5 /B 2 O 3 = 2. Crystals of TiO 2 were black needles or platelets, and those of ZrO 2 and HfO 2 were yellowish, transparent needles or blocks. The maximum size of TiO 2 , ZrO 2 or HfO 2 crystal was 12.0 × 0.1 × 0.1 mm, 4.0 × 0.3 × 0.3 mm or 11.0 × 0.6 × 0.6 mm, respectively. The long axis of the crystals was all C‐axis and main faces on the crystals were of {100} and/or {110} families. All these crystals were found to include the impurities of boron and vanadium. The electrical resistivities of SnO 2 and TiO 2 crystals were measured to be 1.4 × 10 6 and 5.6 × 10 4 Ω · cm at 25°C, respectively.