Growth and characterization of Bi12(Si1 - xTix)O20 mixed crystals

Crystal growth of a sillenite structure with a composition of Bi₁₂(Si_1-xTi_x)O₂₀ and the corresponding optical characteristics have been systematically examined. The incongruent melting materials Bi₁₂TiO₂₀(BTO) have been observed to form a solid solution with congruent melting materials Bi₁₂SiO₂₀(BSO) for the whole range of the x value. The cutoff wavelength increases and the optical activity decreases linearly with BTO content in the crystals. The photorefractive effect is modified significantly due to the addition of BTO. The diffraction efficiency (η) of the photorefractive grating increases first with BTO content for x≤0.33 and saturates for a larger amount of BTO addition. The response speed is, however, promoted markedly for x≥0.48.