Ca_3NbGa_3Si_2O_(14)单晶的光学性质

Optical Properties of Ca_3NbGa_3Si_2O_(14) Single Crystal

Ca3NbGa3Si2O14单晶属硅酸镓镧的同系物,采用提拉技术生长。晶体为透明略带黄色,属三方晶系,32点群。利用TU 1901紫外可见光分光光度计测定透过波段为287～800nm。在可见光范围内用椭圆偏振光谱法测定其非常光折射率ne大于寻常光折射率no,属于正光性单轴晶。通过一种新方法,即利用偏振光分光光度计测量透过率极值,间接计算了旋光度和旋光率,此单晶属右旋晶体,旋光率ρ非常大。在波长670nm处,ρ为31.25°/mm;在波长307nm处,ρ为218.75°/mm。计算了旋光率色散Boltzmann系数,绘制了旋光率色散曲线。

A new ordered langasite isomorph structural piezoelectric Ca_3NbGa_3Si_2O_(14) (CNGS) single crystal was grown by the Czochralski technique. The crystal is slightly yellow and transparent. CNGS single crystal belongs to the trigonal structure. The optical transmission spectra of CNGS crystal from 287 to 800 nm were recorded by Tu-1901 UV-VIS spectrophotometer. The refractive indices n_o and n_e in the visible light region at room temperature were determined using the reflection ellipsometric spectrometry. The optical activities of CNGS were studied by a novel method. The results show that CNGS crystal belongs to right-handed uniaxial crystal and has quite large optical activity. The specific rotation can be up to 62.5 °/mm at 491 nm and 218.75 °/mm at 307 nm. Boltzmann′s coefficients and specific rotation curves of CNGS were measured.