Growth of single crystals of Bi12TiO20 from the stoichiometric melt by a floating zone method

Single crystals Bi12TiO20 (BTO) with various sizes were successfully grown from the stoichiometric melt by a laser-heated floating zone method. The amount of inclusions of Bi4Ti3O12 and Bi2O3 is mainly dependent on the length of the molten zone if the temperature gradient in the grown crystal near the solid-liquid interface is large enough (e.g., about 320degreesC/mm). The transmittance and lattice constant of the produced crystals appear to be little affected by the growth rate if it is less than a critical value. The stoichiometric BTO crystal (grown at 1.0 mm/h) has a lattice constant of a = 10.17370(1) Angstrom. For a nonstoichiometric (Bi2O3 excess) crystal (grown at 1.0 mm/h),its lattice constant decreases [a = 10. 18372(9),- 0.00070189(6)X-TiO2 (Angstrom), where X-TiO2, is in mol%] and its transmittance increases with the concentration of TiO2.