Abstract

This paper describes the growth and photorefractive characteristics of a series of single crystals from solid solution Bi₁₂Si_1-xTi_xO₂₀ of various compositions (x varies from 0.0 to 1.0) in 10-20 mm diameter and 20-40 mm long, that were successfully grown by the Czochralski method. The axial temperature gradient was kept higher than 50°C/cm and the growth rate was kept lower than 0.5 mm/h to prevent cellular growth and inclusions. X-ray phase analysis (XPA) and differential thermal analysis (DTA) have been applied to study the phase diagram of the Bi₁₂Si_1-xTi_xO₂₀ system. The XPA results indicated that all specimens consist of single phase with the sillenite structure and that the concentration dependence of the unit cell parameter was close to linear. The DTA results showed that the liguidus temperature of the samples decreased as the content of Bi₁₂TiO₂₀ increased. From the crystallization and above analysis we confirmed that the unstricted solid solution had occurred in the melts of Bi₁₂Si_1−xTi_xO₂₀. The two wavemixing technique has been applied to characterize photorefractive properties of the crystals, including the photorefractive grating recording and erasing speeds and diffraction efficiency. The diffraction efficiency of a He–Ne probe beam from the grating developed by two argon laser beams was measured to be three times as high as that of pure Bi₁₂SiO₂₀.

© 1992 Optical Society of America