LiNbO_3晶体的坩埚下降法生长

Growth of Lithium Mobate Crystals by the Bridgman Method

通过选择合适的原料配比(Li_2O 48.6mol％,Nb_2O_5 51.4mol％),控制固液界面处的温度梯度为20～40℃/cm,晶体生长速度为0.6～1.5mm/h,采用密闭条件下的坩埚下降法工艺成功地生长出了具有良好光学均匀性的完整LiNbO_3单晶。用X射线粉末衍射表征获得的LiNbO_3晶相,讨论了若干工艺条件对晶体组分与质量的影响。测定了未密闭条件下生长的LiNbO_3晶体不同部位样品的紫外可见光谱,发现其吸收边沿生长方向发生红移,并讨论了产生此现象的原因。

By means of the optimum conditions-the raw materials with proper composition(Li2O 48.6 mol% , Nb2O5 51.4mol%), sealed platinum crucible, growth rate of 0.6-1.5mm/h and a temperature gradient of 20-40℃/cm across the solid-liquid interface-large size crystals without macro-defects were grown successfully by a modified Bridgman method. X-ray diffraction pattern was used to characterize the obtained LiNbO3 crystal. The effects of technical conditions on the composition and quality of crystal were discussed. The UV/visible absorption of the crystal obtained with unsealed crucible was measured, and it is found that the absorption edge is red-shifted along the growing direction, and the reasons were investigated and discussed.