坩埚下降法生长La_2Ti_2O_7晶体及其光性能研究(英文)

Optical Properties of La_2Ti_2O_7 Crystal Grown by Bridgman Method

采用高温坩埚下降法生长La2Ti2O7晶体,获得的晶体尺寸约为18 mm×12 mm×10 mm,其表面出现了一系列(004)解理面。X射线双摇摆曲线表明该晶体具有良好的结晶质量。透过光谱显示退火后的La2Ti2O7晶体在可见光范围内是透明的,当波长在800 nm左右时,透过率将显著下降。La2Ti2O7晶体的吸收边出现在500 nm波长附近。光折射指数分析表明退火La2Ti2O7晶体具有高的折射率。折射率色散方程确定为n2(λ)=4.61643+0.16198/(λ2-0.01547)-0.47201λ2,利用该公式可计算出300～1680 nm范围内任意波长下的折射指数n值。

La2Ti2O7 crystal has been grown by a high-temperature vertical Bridgman method.The as-grown crystal is about 18 mm× 12 mm× 10 mm in dimensions with a series of（004） cleavage planes on the surface.X-ray rocking curve reveals that the crystal has excellent crystalline quality.Transmission spectra implies the annealed La2Ti2O7 crystal is transparent in visible region and drops down quickly near 800 nm.The optical absorption edge is around 500 nm.Refractive index analysis demonstrates the annealed La2Ti2O7 crystal has high refractive property.The dispersion relation is determined to be n2（λ） =4.61643＋0.16198/（λ2-0.01547）-0.47201λ2 which can be used to calculate the refractive index n value at any wavelength in the range of 300-1680 nm.